Merge branch 'master' into jc/cache-tree

* master:
  commit-tree: allow generic object name for the tree as well.
  Makefile: remove and create xdiff library from scratch.
  t0000-basic: Add ls-tree recursive test back.
  Libified diff-index: backward compatibility fix.
  Libify diff-index.
  Libify diff-files.
  Makefile: remove and create libgit.a from scratch.
  Document the configuration file
  Document git-var -l listing also configuration variables
  rev-parse: better error message for ambiguous arguments
  make update-index --chmod work with multiple files and --stdin
  socksetup: don't return on set_reuse_addr() error
  Fix "git show --stat"
  git-update-index --unresolve
  Add git-unresolve <paths>...
  Add colordiff for git to contrib/colordiff.
  gitk: Let git-rev-list do the argument list parsing

22 files changed, 2693 insertions, 2183 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
new file mode 100644
index 000000000..b27b0d5c0
--- /dev/null
+++ b/Documentation/config.txt
@@ -0,0 +1,181 @@
+CONFIGURATION FILE
+------------------
+
+The git configuration file contains a number of variables that affect
+the git commands behaviour. They can be used by both the git plumbing
+and the porcelains. The variables are divided to sections, where
+in the fully qualified variable name the variable itself is the last
+dot-separated segment and the section name is everything before the last
+dot. The variable names are case-insensitive and only alphanumeric
+characters are allowed. Some variables may appear multiple times.
+
+The syntax is fairly flexible and permissive; whitespaces are mostly
+ignored. The '#' and ';' characters begin commends to the end of line,
+blank lines are ignored, lines containing strings enclosed in square
+brackets start sections and all the other lines are recognized
+as setting variables, in the form 'name = value'. If there is no equal
+sign on the line, the entire line is taken as 'name' and the variable
+is recognized as boolean "true". String values may be entirely or partially
+enclosed in double quotes; some variables may require special value format.
+
+Example
+~~~~~~~
+
+	# Core variables
+	[core]
+		; Don't trust file modes
+		filemode = false
+
+	# Our diff algorithm
+	[diff]
+		external = "/usr/local/bin/gnu-diff -u"
+		renames = true
+
+Variables
+~~~~~~~~~
+
+Note that this list is non-comprehensive and not necessarily complete.
+For command-specific variables, you will find more detailed description
+in the appropriate manual page. You will find description of non-core
+porcelain configuration variables in the respective porcelain documentation.
+
+core.fileMode::
+	If false, the executable bit differences between the index and
+	the working copy are ignored; useful on broken filesystems like FAT.
+	See gitlink:git-update-index[1]. True by default.
+
+core.gitProxy::
+	A "proxy command" to execute (as 'command host port') instead
+	of establishing direct connection to the remote server when
+	using the git protocol for fetching. If the variable value is
+	in the "COMMAND for DOMAIN" format, the command is applied only
+	on hostnames ending with the specified domain string. This variable
+	may be set multiple times and is matched in the given order;
+	the first match wins.
+
+	Can be overriden by the 'GIT_PROXY_COMMAND' environment variable
+	(which always applies universally, without the special "for"
+	handling).
+
+core.ignoreStat::
+	The working copy files are assumed to stay unchanged until you
+	mark them otherwise manually - Git will not detect the file changes
+	by lstat() calls. This is useful on systems where those are very
+	slow, such as Microsoft Windows.  See gitlink:git-update-index[1].
+	False by default.
+
+core.onlyUseSymrefs::
+	Always use the "symref" format instead of symbolic links for HEAD
+	and other symbolic reference files. True by default.
+
+core.repositoryFormatVersion::
+	Internal variable identifying the repository format and layout
+	version.
+
+core.sharedRepository::
+	If true, the repository is made shareable between several users
+	in a group (making sure all the files and objects are group-writable).
+	See gitlink:git-init-db[1]. False by default.
+
+core.warnAmbiguousRefs::
+	If true, git will warn you if the ref name you passed it is ambiguous
+	and might match multiple refs in the .git/refs/ tree. True by default.
+
+apply.whitespace::
+	Tells `git-apply` how to handle whitespaces, in the same way
+	as the '--whitespace' option. See gitlink:git-apply[1].
+
+diff.renameLimit::
+	The number of files to consider when performing the copy/rename
+	detection; equivalent to the git diff option '-l'.
+
+format.headers::
+	Additional email headers to include in a patch to be submitted
+	by mail.  See gitlink:git-format-patch[1].
+
+gitcvs.enabled::
+	Whether the cvs pserver interface is enabled for this repository.
+	See gitlink:git-cvsserver[1].
+
+gitcvs.logfile::
+	Path to a log file where the cvs pserver interface well... logs
+	various stuff. See gitlink:git-cvsserver[1].
+
+http.sslVerify::
+	Whether to verify the SSL certificate when fetching or pushing
+	over HTTPS. Can be overriden by the 'GIT_SSL_NO_VERIFY' environment
+	variable.
+
+http.sslCert::
+	File containing the SSL certificate when fetching or pushing
+	over HTTPS. Can be overriden by the 'GIT_SSL_CERT' environment
+	variable.
+
+http.sslKey::
+	File containing the SSL private key when fetching or pushing
+	over HTTPS. Can be overriden by the 'GIT_SSL_KEY' environment
+	variable.
+
+http.sslCAInfo::
+	File containing the certificates to verify the peer with when
+	fetching or pushing over HTTPS. Can be overriden by the
+	'GIT_SSL_CAINFO' environment variable.
+
+http.sslCAPath::
+	Path containing files with the CA certificates to verify the peer
+	with when fetching or pushing over HTTPS. Can be overriden
+	by the 'GIT_SSL_CAPATH' environment variable.
+
+http.maxRequests::
+	How many HTTP requests to launch in parallel. Can be overriden
+	by the 'GIT_HTTP_MAX_REQUESTS' environment variable. Default is 5.
+
+http.lowSpeedLimit, http.lowSpeedTime::
+	If the HTTP transfer speed is less than 'http.lowSpeedLimit'
+	for longer than 'http.lowSpeedTime' seconds, the transfer is aborted.
+	Can be overriden by the 'GIT_HTTP_LOW_SPEED_LIMIT' and
+	'GIT_HTTP_LOW_SPEED_TIME' environment variables.
+
+i18n.commitEncoding::
+	Character encoding the commit messages are stored in; git itself
+	does not care per se, but this information is necessary e.g. when
+	importing commits from emails or in the gitk graphical history
+	browser (and possibly at other places in the future or in other
+	porcelains). See e.g. gitlink:git-mailinfo[1]. Defaults to 'utf-8'.
+
+merge.summary::
+	Whether to include summaries of merged commits in newly created
+	merge commit messages. False by default.
+
+pull.octopus::
+	The default merge strategy to use when pulling multiple branches
+	at once.
+
+pull.twohead::
+	The default merge strategy to use when pulling a single branch.
+
+show.difftree::
+	The default gitlink:git-diff-tree[1] arguments to be used
+	for gitlink:git-show[1].
+
+showbranch.default::
+	The default set of branches for gitlink:git-show-branch[1].
+	See gitlink:git-show-branch[1].
+
+user.email::
+	Your email address to be recorded in any newly created commits.
+	Can be overriden by the 'GIT_AUTHOR_EMAIL' and 'GIT_COMMITTER_EMAIL'
+	environment variables.  See gitlink:git-commit-tree[1].
+
+user.name::
+	Your full name to be recorded in any newly created commits.
+	Can be overriden by the 'GIT_AUTHOR_NAME' and 'GIT_COMMITTER_NAME'
+	environment variables.  See gitlink:git-commit-tree[1].
+
+whatchanged.difftree::
+	The default gitlink:git-diff-tree[1] arguments to be used
+	for gitlink:git-whatchanged[1].
+
+imap::
+	The configuration variables in the 'imap' section are described
+	in gitlink:git-imap-send[1].
diff --git a/Documentation/git-repo-config.txt b/Documentation/git-repo-config.txt
index 26759a807..71f96bdd1 100644
--- a/Documentation/git-repo-config.txt
+++ b/Documentation/git-repo-config.txt
@@ -87,11 +87,11 @@ Given a .git/config like this:
 		renames = true
 
 	; Proxy settings
-	[proxy]
-		command="ssh" for "ssh://kernel.org/"
-		command="proxy-command" for kernel.org
-		command="myprotocol-command" for "my://"
-		command=default-proxy ; for all the rest
+	[core]
+		gitproxy="ssh" for "ssh://kernel.org/"
+		gitproxy="proxy-command" for kernel.org
+		gitproxy="myprotocol-command" for "my://"
+		gitproxy=default-proxy ; for all the rest
 
 you can set the filemode to true with
 
@@ -104,7 +104,7 @@ to what URL they apply. Here is how to change the entry for kernel.org
 to "ssh".
 
 ------------
-% git repo-config proxy.command '"ssh" for kernel.org' 'for kernel.org$'
+% git repo-config core.gitproxy '"ssh" for kernel.org' 'for kernel.org$'
 ------------
 
 This makes sure that only the key/value pair for kernel.org is replaced.
@@ -115,7 +115,7 @@ To delete the entry for renames, do
 % git repo-config --unset diff.renames
 ------------
 
-If you want to delete an entry for a multivar (like proxy.command above),
+If you want to delete an entry for a multivar (like core.gitproxy above),
 you have to provide a regex matching the value of exactly one line.
 
 To query the value for a given key, do
@@ -133,27 +133,27 @@ or
 or, to query a multivar:
 
 ------------
-% git repo-config --get proxy.command "for kernel.org$"
+% git repo-config --get core.gitproxy "for kernel.org$"
 ------------
 
 If you want to know all the values for a multivar, do:
 
 ------------
-% git repo-config --get-all proxy.command
+% git repo-config --get-all core.gitproxy
 ------------
 
-If you like to live dangerous, you can replace *all* proxy.commands by a
+If you like to live dangerous, you can replace *all* core.gitproxy by a
 new one with
 
 ------------
-% git repo-config --replace-all proxy.command ssh
+% git repo-config --replace-all core.gitproxy ssh
 ------------
 
 However, if you really only want to replace the line for the default proxy,
 i.e. the one without a "for ..." postfix, do something like this:
 
 ------------
-% git repo-config proxy.command ssh '! for '
+% git repo-config core.gitproxy ssh '! for '
 ------------
 
 To actually match only values with an exclamation mark, you have to
@@ -163,13 +163,16 @@ To actually match only values with an exclamation mark, you have to
 ------------
 
 
+include::config.txt[]
+
+
 Author
 ------
 Written by Johannes Schindelin <Johannes.Schindelin@gmx.de>
 
 Documentation
 --------------
-Documentation by Johannes Schindelin.
+Documentation by Johannes Schindelin, Petr Baudis and the git-list <git@vger.kernel.org>.
 
 GIT
 ---
diff --git a/Documentation/git-var.txt b/Documentation/git-var.txt
index 90cb157be..379571eef 100644
--- a/Documentation/git-var.txt
+++ b/Documentation/git-var.txt
@@ -17,7 +17,9 @@ Prints a git logical variable.
 OPTIONS
 -------
 -l::
-	Cause the logical variables to be listed.
+	Cause the logical variables to be listed. In addition, all the
+	variables of the git configuration file .git/config are listed
+	as well.
 
 EXAMPLE
 --------
@@ -46,6 +48,7 @@ See Also
 --------
 gitlink:git-commit-tree[1]
 gitlink:git-tag[1]
+gitlink:git-repo-config[1]
 
 Author
 ------
diff --git a/Makefile b/Makefile
index 1aa96f4f2..d2cc01a26 100644
--- a/Makefile
+++ b/Makefile
@@ -199,7 +199,7 @@ LIB_H = \
 	tree-walk.h log-tree.h
 
 DIFF_OBJS = \
-	diff-lib.o diffcore-break.o diffcore-order.o \
+	diff.o diff-lib.o diffcore-break.o diffcore-order.o \
 	diffcore-pickaxe.o diffcore-rename.o tree-diff.o combine-diff.o \
 	diffcore-delta.o log-tree.o
 
@@ -575,12 +575,12 @@ $(patsubst git-%$X,%.o,$(PROGRAMS)): $(GITLIBS)
 $(DIFF_OBJS): diffcore.h
 
 $(LIB_FILE): $(LIB_OBJS)
-	$(AR) rcs $@ $(LIB_OBJS)
+	rm -f $@ && $(AR) rcs $@ $(LIB_OBJS)
 
 XDIFF_OBJS=xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o
 
 $(XDIFF_LIB): $(XDIFF_OBJS)
-	$(AR) rcs $@ $(XDIFF_OBJS)
+	rm -f $@ && $(AR) rcs $@ $(XDIFF_OBJS)
 
 
 doc:
diff --git a/commit-tree.c b/commit-tree.c
index 2d8651894..e91af4bd3 100644
--- a/commit-tree.c
+++ b/commit-tree.c
@@ -92,7 +92,7 @@ int main(int argc, char **argv)
 
 	git_config(git_default_config);
 
-	if (argc < 2 || get_sha1_hex(argv[1], tree_sha1) < 0)
+	if (argc < 2 || get_sha1(argv[1], tree_sha1) < 0)
 		usage(commit_tree_usage);
 
 	check_valid(tree_sha1, tree_type);
diff --git a/config.c b/config.c
index 7ea8a7369..4e1f0c228 100644
--- a/config.c
+++ b/config.c
@@ -252,7 +252,7 @@ int git_default_config(const char *var, const char *value)
 		return 0;
 	}
 
-	/* Add other config variables here.. */
+	/* Add other config variables here and to Documentation/config.txt. */
 	return 0;
 }
 
diff --git a/contrib/colordiff/README b/contrib/colordiff/README
new file mode 100644
index 000000000..2678fdf9c
--- /dev/null
+++ b/contrib/colordiff/README
@@ -0,0 +1,2 @@
+This is "colordiff" (http://colordiff.sourceforge.net/) by Dave
+Ewart <davee@sungate.co.uk>, modified specifically for git.
diff --git a/contrib/colordiff/colordiff.perl b/contrib/colordiff/colordiff.perl
new file mode 100755
index 000000000..5789cfb26
--- /dev/null
+++ b/contrib/colordiff/colordiff.perl
@@ -0,0 +1,196 @@
+#!/usr/bin/perl -w
+#
+# $Id: colordiff.pl,v 1.4.2.10 2004/01/04 15:02:59 daveewart Exp $
+
+########################################################################
+#                                                                      #
+# ColorDiff - a wrapper/replacment for 'diff' producing                #
+#             colourful output                                         #
+#                                                                      #
+# Copyright (C)2002-2004 Dave Ewart (davee@sungate.co.uk)              #
+#                                                                      #
+########################################################################
+#                                                                      #
+# This program is free software; you can redistribute it and/or modify #
+# it under the terms of the GNU General Public License as published by #
+# the Free Software Foundation; either version 2 of the License, or    #
+# (at your option) any later version.                                  #
+#                                                                      #
+# This program is distributed in the hope that it will be useful,      #
+# but WITHOUT ANY WARRANTY; without even the implied warranty of       #
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        #
+# GNU General Public License for more details.                         #
+#                                                                      #
+# You should have received a copy of the GNU General Public License    #
+# along with this program; if not, write to the Free Software          #
+# Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.            #
+#                                                                      #
+########################################################################
+
+use strict;
+use Getopt::Long qw(:config pass_through);
+use IPC::Open2;
+
+my $app_name     = 'colordiff';
+my $version      = '1.0.4';
+my $author       = 'Dave Ewart';
+my $author_email = 'davee@sungate.co.uk';
+my $app_www      = 'http://colordiff.sourceforge.net/';
+my $copyright    = '(C)2002-2004';
+my $show_banner  = 1;
+
+# ANSI sequences for colours
+my %colour;
+$colour{white}       = "\033[1;37m";
+$colour{yellow}      = "\033[1;33m";
+$colour{green}       = "\033[1;32m";
+$colour{blue}        = "\033[1;34m";
+$colour{cyan}        = "\033[1;36m";
+$colour{red}         = "\033[1;31m";
+$colour{magenta}     = "\033[1;35m";
+$colour{black}       = "\033[1;30m";
+$colour{darkwhite}   = "\033[0;37m";
+$colour{darkyellow}  = "\033[0;33m";
+$colour{darkgreen}   = "\033[0;32m";
+$colour{darkblue}    = "\033[0;34m";
+$colour{darkcyan}    = "\033[0;36m";
+$colour{darkred}     = "\033[0;31m";
+$colour{darkmagenta} = "\033[0;35m";
+$colour{darkblack}   = "\033[0;30m";
+$colour{OFF}         = "\033[0;0m";
+
+# Default colours if /etc/colordiffrc or ~/.colordiffrc do not exist
+my $plain_text = $colour{OFF};
+my $file_old   = $colour{red};
+my $file_new   = $colour{blue};
+my $diff_stuff = $colour{magenta};
+
+# Locations for personal and system-wide colour configurations
+my $HOME   = $ENV{HOME};
+my $etcdir = '/etc';
+
+my ($setting, $value);
+my @config_files = ("$etcdir/colordiffrc", "$HOME/.colordiffrc");
+my $config_file;
+
+foreach $config_file (@config_files) {
+    if (open(COLORDIFFRC, "<$config_file")) {
+        while (<COLORDIFFRC>) {
+            chop;
+            next if (/^#/ || /^$/);
+            s/\s+//g;
+            ($setting, $value) = split ('=');
+            if ($setting eq 'banner') {
+                if ($value eq 'no') {
+                    $show_banner = 0;
+                }
+                next;
+            }
+            if (!defined $colour{$value}) {
+                print "Invalid colour specification ($value) in $config_file\n";
+                next;
+            }
+            if ($setting eq 'plain') {
+                $plain_text = $colour{$value};
+            }
+            elsif ($setting eq 'oldtext') {
+                $file_old = $colour{$value};
+            }
+            elsif ($setting eq 'newtext') {
+                $file_new = $colour{$value};
+            }
+            elsif ($setting eq 'diffstuff') {
+                $diff_stuff = $colour{$value};
+            }
+            else {
+                print "Unknown option in $etcdir/colordiffrc: $setting\n";
+            }
+        }
+        close COLORDIFFRC;
+    }
+}
+
+# colordiff specfic options here.  Need to pre-declare if using variables
+GetOptions(
+    "no-banner" => sub { $show_banner = 0 },
+    "plain-text=s" => \&set_color,
+    "file-old=s"   => \&set_color,
+    "file-new=s"   => \&set_color,
+    "diff-stuff=s" => \&set_color
+);
+
+if ($show_banner == 1) {
+    print STDERR "$app_name $version ($app_www)\n";
+    print STDERR "$copyright $author, $author_email\n\n";
+}
+
+if (defined $ARGV[0]) {
+    # More reliable way of pulling in arguments
+    open2(\*INPUTSTREAM, undef, "git", "diff", @ARGV);
+}
+else {
+    *INPUTSTREAM = \*STDIN;
+}
+
+my $record;
+my $nrecs           = 0;
+my $inside_file_old = 1;
+my $nparents        = undef;
+
+while (<INPUTSTREAM>) {
+    $nrecs++;
+    if (/^(\@\@+) -[-+0-9, ]+ \1/) {
+	    print "$diff_stuff";
+	    $nparents = length($1) - 1;
+    }
+    elsif (/^diff -/ || /^index / ||
+	   /^old mode / || /^new mode / ||
+	   /^deleted file mode / || /^new file mode / ||
+	   /^similarity index / || /^dissimilarity index / ||
+	   /^copy from / || /^copy to / ||
+	   /^rename from / || /^rename to /) {
+	    $nparents = undef;
+	    print "$diff_stuff";
+    }
+    elsif (defined $nparents) {
+	    if ($nparents == 1) {
+		    if (/^\+/) {
+			    print $file_new;
+		    }
+		    elsif (/^-/) {
+			    print $file_old;
+		    }
+		    else {
+			    print $plain_text;
+		    }
+	    }
+	    elsif (/^ {$nparents}/) {
+		    print "$plain_text";
+	    }
+	    elsif (/^[+ ]{$nparents}/) {
+		    print "$file_new";
+	    }
+	    elsif (/^[- ]{$nparents}/) {
+		    print "$file_old";
+	    }
+	    else {
+		    print $plain_text;
+	    }
+    }
+    elsif (/^--- / || /^\+\+\+ /) {
+	    print $diff_stuff;
+    }
+    else {
+	    print "$plain_text";
+    }
+    s/$/$colour{OFF}/;
+    print "$_";
+}
+close INPUTSTREAM;
+
+sub set_color {
+    my ($type, $color) = @_;
+
+    $type =~ s/-/_/;
+    eval "\$$type = \$colour{$color}";
+}
diff --git a/daemon.c b/daemon.c
index a1ccda30e..776749e34 100644
--- a/daemon.c
+++ b/daemon.c
@@ -535,7 +535,7 @@ static int socksetup(int port, int **socklist_p)
 
 		if (set_reuse_addr(sockfd)) {
 			close(sockfd);
-			return 0;	/* not fatal */
+			continue;
 		}
 
 		if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
diff --git a/diff-files.c b/diff-files.c
index ffbef48b2..b9d193d50 100644
--- a/diff-files.c
+++ b/diff-files.c
@@ -12,203 +12,43 @@ static const char diff_files_usage[] =
 "git-diff-files [-q] [-0/-1/2/3 |-c|--cc] [<common diff options>] [<path>...]"
 COMMON_DIFF_OPTIONS_HELP;
 
-static struct rev_info rev;
-static int silent = 0;
-static int diff_unmerged_stage = 2;
-static int combine_merges = 0;
-static int dense_combined_merges = 0;
-
-static void show_unmerge(const char *path)
-{
-	diff_unmerge(&rev.diffopt, path);
-}
-
-static void show_file(int pfx, struct cache_entry *ce)
-{
-	diff_addremove(&rev.diffopt, pfx, ntohl(ce->ce_mode),
-		       ce->sha1, ce->name, NULL);
-}
-
-static void show_modified(int oldmode, int mode,
-			  const unsigned char *old_sha1, const unsigned char *sha1,
-			  char *path)
-{
-	diff_change(&rev.diffopt, oldmode, mode, old_sha1, sha1, path, NULL);
-}
-
 int main(int argc, const char **argv)
 {
-	const char **pathspec;
-	const char *prefix = setup_git_directory();
-	int entries, i;
+	struct rev_info rev;
+	int silent = 0;
 
 	git_config(git_diff_config);
-	diff_setup(&rev.diffopt);
+	init_revisions(&rev);
+	rev.abbrev = 0;
+
+	argc = setup_revisions(argc, argv, &rev, NULL);
 	while (1 < argc && argv[1][0] == '-') {
-		if (!strcmp(argv[1], "--")) {
-			argv++;
-			argc--;
-			break;
-		}
-		if (!strcmp(argv[1], "-0"))
-			diff_unmerged_stage = 0;
-		else if (!strcmp(argv[1], "-1"))
-			diff_unmerged_stage = 1;
-		else if (!strcmp(argv[1], "-2"))
-			diff_unmerged_stage = 2;
-		else if (!strcmp(argv[1], "-3"))
-			diff_unmerged_stage = 3;
-		else if (!strcmp(argv[1], "--base"))
-			diff_unmerged_stage = 1;
+		if (!strcmp(argv[1], "--base"))
+			rev.max_count = 1;
 		else if (!strcmp(argv[1], "--ours"))
-			diff_unmerged_stage = 2;
+			rev.max_count = 2;
 		else if (!strcmp(argv[1], "--theirs"))
-			diff_unmerged_stage = 3;
+			rev.max_count = 3;
 		else if (!strcmp(argv[1], "-q"))
 			silent = 1;
-		else if (!strcmp(argv[1], "-r"))
-			; /* no-op */
-		else if (!strcmp(argv[1], "-s"))
-			; /* no-op */
-		else if (!strcmp(argv[1], "-c"))
-			combine_merges = 1;
-		else if (!strcmp(argv[1], "--cc"))
-			dense_combined_merges = combine_merges = 1;
-		else {
-			int diff_opt_cnt;
-			diff_opt_cnt = diff_opt_parse(&rev.diffopt,
-						      argv+1, argc-1);
-			if (diff_opt_cnt < 0)
-				usage(diff_files_usage);
-			else if (diff_opt_cnt) {
-				argv += diff_opt_cnt;
-				argc -= diff_opt_cnt;
-				continue;
-			}
-			else
-				usage(diff_files_usage);
-		}
+		else
+			usage(diff_files_usage);
 		argv++; argc--;
 	}
-	if (dense_combined_merges)
-		rev.diffopt.output_format = DIFF_FORMAT_PATCH;
-
-	/* Find the directory, and set up the pathspec */
-	pathspec = get_pathspec(prefix, argv + 1);
-	entries = read_cache();
-
-	if (diff_setup_done(&rev.diffopt) < 0)
+	/*
+	 * Make sure there are NO revision (i.e. pending object) parameter,
+	 * rev.max_count is reasonable (0 <= n <= 3),
+	 * there is no other revision filtering parameters.
+	 */
+	if (rev.pending_objects ||
+	    rev.min_age != -1 || rev.max_age != -1)
 		usage(diff_files_usage);
-
-	/* At this point, if argc == 1, then we are doing everything.
-	 * Otherwise argv[1] .. argv[argc-1] have the explicit paths.
+	/*
+	 * Backward compatibility wart - "diff-files -s" used to
+	 * defeat the common diff option "-s" which asked for
+	 * DIFF_FORMAT_NO_OUTPUT.
 	 */
-	if (entries < 0) {
-		perror("read_cache");
-		exit(1);
-	}
-
-	for (i = 0; i < entries; i++) {
-		struct stat st;
-		unsigned int oldmode, newmode;
-		struct cache_entry *ce = active_cache[i];
-		int changed;
-
-		if (!ce_path_match(ce, pathspec))
-			continue;
-
-		if (ce_stage(ce)) {
-			struct {
-				struct combine_diff_path p;
-				struct combine_diff_parent filler[5];
-			} combine;
-			int num_compare_stages = 0;
-
-			combine.p.next = NULL;
-			combine.p.len = ce_namelen(ce);
-			combine.p.path = xmalloc(combine.p.len + 1);
-			memcpy(combine.p.path, ce->name, combine.p.len);
-			combine.p.path[combine.p.len] = 0;
-			combine.p.mode = 0;
-			memset(combine.p.sha1, 0, 20);
-			memset(&combine.p.parent[0], 0,
-			       sizeof(combine.filler));
-
-			while (i < entries) {
-				struct cache_entry *nce = active_cache[i];
-				int stage;
-
-				if (strcmp(ce->name, nce->name))
-					break;
-
-				/* Stage #2 (ours) is the first parent,
-				 * stage #3 (theirs) is the second.
-				 */
-				stage = ce_stage(nce);
-				if (2 <= stage) {
-					int mode = ntohl(nce->ce_mode);
-					num_compare_stages++;
-					memcpy(combine.p.parent[stage-2].sha1,
-					       nce->sha1, 20);
-					combine.p.parent[stage-2].mode =
-						canon_mode(mode);
-					combine.p.parent[stage-2].status =
-						DIFF_STATUS_MODIFIED;
-				}
-
-				/* diff against the proper unmerged stage */
-				if (stage == diff_unmerged_stage)
-					ce = nce;
-				i++;
-			}
-			/*
-			 * Compensate for loop update
-			 */
-			i--;
-
-			if (combine_merges && num_compare_stages == 2) {
-				show_combined_diff(&combine.p, 2,
-						   dense_combined_merges,
-						   &rev);
-				free(combine.p.path);
-				continue;
-			}
-			free(combine.p.path);
-
-			/*
-			 * Show the diff for the 'ce' if we found the one
-			 * from the desired stage.
-			 */
-			show_unmerge(ce->name);
-			if (ce_stage(ce) != diff_unmerged_stage)
-				continue;
-		}
-
-		if (lstat(ce->name, &st) < 0) {
-			if (errno != ENOENT && errno != ENOTDIR) {
-				perror(ce->name);
-				continue;
-			}
-			if (silent)
-				continue;
-			show_file('-', ce);
-			continue;
-		}
-		changed = ce_match_stat(ce, &st, 0);
-		if (!changed && !rev.diffopt.find_copies_harder)
-			continue;
-		oldmode = ntohl(ce->ce_mode);
-
-		newmode = canon_mode(st.st_mode);
-		if (!trust_executable_bit &&
-		    S_ISREG(newmode) && S_ISREG(oldmode) &&
-		    ((newmode ^ oldmode) == 0111))
-			newmode = oldmode;
-		show_modified(oldmode, newmode,
-			      ce->sha1, (changed ? null_sha1 : ce->sha1),
-			      ce->name);
-	}
-	diffcore_std(&rev.diffopt);
-	diff_flush(&rev.diffopt);
-	return 0;
+	if (rev.diffopt.output_format == DIFF_FORMAT_NO_OUTPUT)
+		rev.diffopt.output_format = DIFF_FORMAT_RAW;
+	return run_diff_files(&rev, silent);
 }
diff --git a/diff-index.c b/diff-index.c
index e376d65f8..86940123b 100644
--- a/diff-index.c
+++ b/diff-index.c
@@ -1,166 +1,7 @@
 #include "cache.h"
-#include "tree.h"
 #include "diff.h"
-
-static int cached_only = 0;
-static int match_nonexisting = 0;
-static struct diff_options diff_options;
-
-/* A file entry went away or appeared */
-static void show_file(const char *prefix,
-		      struct cache_entry *ce,
-		      unsigned char *sha1, unsigned int mode)
-{
-	diff_addremove(&diff_options, prefix[0], ntohl(mode),
-		       sha1, ce->name, NULL);
-}
-
-static int get_stat_data(struct cache_entry *ce,
-			 unsigned char ** sha1p, unsigned int *modep)
-{
-	unsigned char *sha1 = ce->sha1;
-	unsigned int mode = ce->ce_mode;
-
-	if (!cached_only) {
-		static unsigned char no_sha1[20];
-		int changed;
-		struct stat st;
-		if (lstat(ce->name, &st) < 0) {
-			if (errno == ENOENT && match_nonexisting) {
-				*sha1p = sha1;
-				*modep = mode;
-				return 0;
-			}
-			return -1;
-		}
-		changed = ce_match_stat(ce, &st, 0);
-		if (changed) {
-			mode = create_ce_mode(st.st_mode);
-			if (!trust_executable_bit && S_ISREG(st.st_mode))
-				mode = ce->ce_mode;
-			sha1 = no_sha1;
-		}
-	}
-
-	*sha1p = sha1;
-	*modep = mode;
-	return 0;
-}
-
-static void show_new_file(struct cache_entry *new)
-{
-	unsigned char *sha1;
-	unsigned int mode;
-
-	/* New file in the index: it might actually be different in
-	 * the working copy.
-	 */
-	if (get_stat_data(new, &sha1, &mode) < 0)
-		return;
-
-	show_file("+", new, sha1, mode);
-}
-
-static int show_modified(struct cache_entry *old,
-			 struct cache_entry *new,
-			 int report_missing)
-{
-	unsigned int mode, oldmode;
-	unsigned char *sha1;
-
-	if (get_stat_data(new, &sha1, &mode) < 0) {
-		if (report_missing)
-			show_file("-", old, old->sha1, old->ce_mode);
-		return -1;
-	}
-
-	oldmode = old->ce_mode;
-	if (mode == oldmode && !memcmp(sha1, old->sha1, 20) &&
-	    !diff_options.find_copies_harder)
-		return 0;
-
-	mode = ntohl(mode);
-	oldmode = ntohl(oldmode);
-
-	diff_change(&diff_options, oldmode, mode,
-		    old->sha1, sha1, old->name, NULL);
-	return 0;
-}
-
-static int diff_cache(struct cache_entry **ac, int entries, const char **pathspec)
-{
-	while (entries) {
-		struct cache_entry *ce = *ac;
-		int same = (entries > 1) && ce_same_name(ce, ac[1]);
-
-		if (!ce_path_match(ce, pathspec))
-			goto skip_entry;
-
-		switch (ce_stage(ce)) {
-		case 0:
-			/* No stage 1 entry? That means it's a new file */
-			if (!same) {
-				show_new_file(ce);
-				break;
-			}
-			/* Show difference between old and new */
-			show_modified(ac[1], ce, 1);
-			break;
-		case 1:
-			/* No stage 3 (merge) entry? That means it's been deleted */
-			if (!same) {
-				show_file("-", ce, ce->sha1, ce->ce_mode);
-				break;
-			}
-			/* We come here with ce pointing at stage 1
-			 * (original tree) and ac[1] pointing at stage
-			 * 3 (unmerged).  show-modified with
-			 * report-missing set to false does not say the
-			 * file is deleted but reports true if work
-			 * tree does not have it, in which case we
-			 * fall through to report the unmerged state.
-			 * Otherwise, we show the differences between
-			 * the original tree and the work tree.
-			 */
-			if (!cached_only && !show_modified(ce, ac[1], 0))
-				break;
-			/* fallthru */
-		case 3:
-			diff_unmerge(&diff_options, ce->name);
-			break;
-
-		default:
-			die("impossible cache entry stage");
-		}
-
-skip_entry:
-		/*
-		 * Ignore all the different stages for this file,
-		 * we've handled the relevant cases now.
-		 */
-		do {
-			ac++;
-			entries--;
-		} while (entries && ce_same_name(ce, ac[0]));
-	}
-	return 0;
-}
-
-/*
- * This turns all merge entries into "stage 3". That guarantees that
- * when we read in the new tree (into "stage 1"), we won't lose sight
- * of the fact that we had unmerged entries.
- */
-static void mark_merge_entries(void)
-{
-	int i;
-	for (i = 0; i < active_nr; i++) {
-		struct cache_entry *ce = active_cache[i];
-		if (!ce_stage(ce))
-			continue;
-		ce->ce_flags |= htons(CE_STAGEMASK);
-	}
-}
+#include "commit.h"
+#include "revision.h"
 
 static const char diff_cache_usage[] =
 "git-diff-index [-m] [--cached] "
@@ -169,85 +10,30 @@ COMMON_DIFF_OPTIONS_HELP;
 
 int main(int argc, const char **argv)
 {
-	const char *tree_name = NULL;
-	unsigned char sha1[20];
-	const char *prefix = setup_git_directory();
-	const char **pathspec = NULL;
-	struct tree *tree;
-	int ret;
-	int allow_options = 1;
+	struct rev_info rev;
+	int match_missing = 0;
+	int cached = 0;
 	int i;
 
 	git_config(git_diff_config);
-	diff_setup(&diff_options);
+	init_revisions(&rev);
+	rev.abbrev = 0;
+
+	argc = setup_revisions(argc, argv, &rev, NULL);
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
-		int diff_opt_cnt;
-
-		if (!allow_options || *arg != '-') {
-			if (tree_name)
-				break;
-			tree_name = arg;
-			continue;
-		}
 			
-		if (!strcmp(arg, "--")) {
-			allow_options = 0;
-			continue;
-		}
-		if (!strcmp(arg, "-r")) {
-			/* We accept the -r flag just to look like git-diff-tree */
-			continue;
-		}
-		if (!strcmp(arg, "--cc"))
-			/*
-			 * I _think_ "diff-index --cached HEAD" with an
-			 * unmerged index could show something else
-			 * later, but pretend --cc is the same as -p for
-			 * now.  "git diff" uses --cc by default.
-			 */
-			argv[i] = arg = "-p";
-		diff_opt_cnt = diff_opt_parse(&diff_options, argv + i,
-					      argc - i);
-		if (diff_opt_cnt < 0)
+		if (!strcmp(arg, "--cached"))
+			cached = 1;
+		else
 			usage(diff_cache_usage);
-		else if (diff_opt_cnt) {
-			i += diff_opt_cnt - 1;
-			continue;
-		}
-
-		if (!strcmp(arg, "-m")) {
-			match_nonexisting = 1;
-			continue;
-		}
-		if (!strcmp(arg, "--cached")) {
-			cached_only = 1;
-			continue;
-		}
-		usage(diff_cache_usage);
 	}
-
-	pathspec = get_pathspec(prefix, argv + i);
-
-	if (diff_setup_done(&diff_options) < 0)
-		usage(diff_cache_usage);
-
-	if (!tree_name || get_sha1(tree_name, sha1))
+	/*
+	 * Make sure there is one revision (i.e. pending object),
+	 * and there is no revision filtering parameters.
+	 */
+	if (!rev.pending_objects || rev.pending_objects->next ||
+	    rev.max_count != -1 || rev.min_age != -1 || rev.max_age != -1)
 		usage(diff_cache_usage);
-
-	read_cache();
-
-	mark_merge_entries();
-
-	tree = parse_tree_indirect(sha1);
-	if (!tree)
-		die("bad tree object %s", tree_name);
-	if (read_tree(tree, 1, pathspec))
-		die("unable to read tree object %s", tree_name);
-
-	ret = diff_cache(active_cache, active_nr, pathspec);
-
-	diffcore_std(&diff_options);
-	diff_flush(&diff_options);
-	return ret;
+	return run_diff_index(&rev, cached);
 }
diff --git a/diff-lib.c b/diff-lib.c
index 13b216f27..2183b41b0 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -1,1795 +1,344 @@
 /*
  * Copyright (C) 2005 Junio C Hamano
  */
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <signal.h>
 #include "cache.h"
 #include "quote.h"
+#include "commit.h"
 #include "diff.h"
 #include "diffcore.h"
-#include "xdiff-interface.h"
+#include "revision.h"
 
-static int use_size_cache;
-
-int diff_rename_limit_default = -1;
-
-int git_diff_config(const char *var, const char *value)
-{
-	if (!strcmp(var, "diff.renamelimit")) {
-		diff_rename_limit_default = git_config_int(var, value);
-		return 0;
-	}
-
-	return git_default_config(var, value);
-}
-
-static char *quote_one(const char *str)
-{
-	int needlen;
-	char *xp;
-
-	if (!str)
-		return NULL;
-	needlen = quote_c_style(str, NULL, NULL, 0);
-	if (!needlen)
-		return strdup(str);
-	xp = xmalloc(needlen + 1);
-	quote_c_style(str, xp, NULL, 0);
-	return xp;
-}
-
-static char *quote_two(const char *one, const char *two)
-{
-	int need_one = quote_c_style(one, NULL, NULL, 1);
-	int need_two = quote_c_style(two, NULL, NULL, 1);
-	char *xp;
-
-	if (need_one + need_two) {
-		if (!need_one) need_one = strlen(one);
-		if (!need_two) need_one = strlen(two);
-
-		xp = xmalloc(need_one + need_two + 3);
-		xp[0] = '"';
-		quote_c_style(one, xp + 1, NULL, 1);
-		quote_c_style(two, xp + need_one + 1, NULL, 1);
-		strcpy(xp + need_one + need_two + 1, "\"");
-		return xp;
-	}
-	need_one = strlen(one);
-	need_two = strlen(two);
-	xp = xmalloc(need_one + need_two + 1);
-	strcpy(xp, one);
-	strcpy(xp + need_one, two);
-	return xp;
-}
-
-static const char *external_diff(void)
-{
-	static const char *external_diff_cmd = NULL;
-	static int done_preparing = 0;
-
-	if (done_preparing)
-		return external_diff_cmd;
-	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
-	done_preparing = 1;
-	return external_diff_cmd;
-}
-
-#define TEMPFILE_PATH_LEN		50
-
-static struct diff_tempfile {
-	const char *name; /* filename external diff should read from */
-	char hex[41];
-	char mode[10];
-	char tmp_path[TEMPFILE_PATH_LEN];
-} diff_temp[2];
-
-static int count_lines(const char *data, int size)
-{
-	int count, ch, completely_empty = 1, nl_just_seen = 0;
-	count = 0;
-	while (0 < size--) {
-		ch = *data++;
-		if (ch == '\n') {
-			count++;
-			nl_just_seen = 1;
-			completely_empty = 0;
-		}
-		else {
-			nl_just_seen = 0;
-			completely_empty = 0;
-		}
-	}
-	if (completely_empty)
-		return 0;
-	if (!nl_just_seen)
-		count++; /* no trailing newline */
-	return count;
-}
-
-static void print_line_count(int count)
-{
-	switch (count) {
-	case 0:
-		printf("0,0");
-		break;
-	case 1:
-		printf("1");
-		break;
-	default:
-		printf("1,%d", count);
-		break;
-	}
-}
-
-static void copy_file(int prefix, const char *data, int size)
-{
-	int ch, nl_just_seen = 1;
-	while (0 < size--) {
-		ch = *data++;
-		if (nl_just_seen)
-			putchar(prefix);
-		putchar(ch);
-		if (ch == '\n')
-			nl_just_seen = 1;
-		else
-			nl_just_seen = 0;
-	}
-	if (!nl_just_seen)
-		printf("\n\\ No newline at end of file\n");
-}
+/*
+ * diff-files
+ */
 
-static void emit_rewrite_diff(const char *name_a,
-			      const char *name_b,
-			      struct diff_filespec *one,
-			      struct diff_filespec *two)
+int run_diff_files(struct rev_info *revs, int silent_on_removed)
 {
-	int lc_a, lc_b;
-	diff_populate_filespec(one, 0);
-	diff_populate_filespec(two, 0);
-	lc_a = count_lines(one->data, one->size);
-	lc_b = count_lines(two->data, two->size);
-	printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
-	print_line_count(lc_a);
-	printf(" +");
-	print_line_count(lc_b);
-	printf(" @@\n");
-	if (lc_a)
-		copy_file('-', one->data, one->size);
-	if (lc_b)
-		copy_file('+', two->data, two->size);
-}
+	int entries, i;
+	int diff_unmerged_stage = revs->max_count;
 
-static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
-{
-	if (!DIFF_FILE_VALID(one)) {
-		mf->ptr = ""; /* does not matter */
-		mf->size = 0;
-		return 0;
-	}
-	else if (diff_populate_filespec(one, 0))
+	if (diff_unmerged_stage < 0)
+		diff_unmerged_stage = 2;
+	entries = read_cache();
+	if (entries < 0) {
+		perror("read_cache");
 		return -1;
-	mf->ptr = one->data;
-	mf->size = one->size;
-	return 0;
-}
-
-struct emit_callback {
-	const char **label_path;
-};
-
-static int fn_out(void *priv, mmbuffer_t *mb, int nbuf)
-{
-	int i;
-	struct emit_callback *ecbdata = priv;
-
-	if (ecbdata->label_path[0]) {
-		printf("--- %s\n", ecbdata->label_path[0]);
-		printf("+++ %s\n", ecbdata->label_path[1]);
-		ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
 	}
-	for (i = 0; i < nbuf; i++)
-		if (!fwrite(mb[i].ptr, mb[i].size, 1, stdout))
-			return -1;
-	return 0;
-}
-
-static char *pprint_rename(const char *a, const char *b)
-{
-	const char *old = a;
-	const char *new = b;
-	char *name = NULL;
-	int pfx_length, sfx_length;
-	int len_a = strlen(a);
-	int len_b = strlen(b);
-
-	/* Find common prefix */
-	pfx_length = 0;
-	while (*old && *new && *old == *new) {
-		if (*old == '/')
-			pfx_length = old - a + 1;
-		old++;
-		new++;
-	}
-
-	/* Find common suffix */
-	old = a + len_a;
-	new = b + len_b;
-	sfx_length = 0;
-	while (a <= old && b <= new && *old == *new) {
-		if (*old == '/')
-			sfx_length = len_a - (old - a);
-		old--;
-		new--;
-	}
-
-	/*
-	 * pfx{mid-a => mid-b}sfx
-	 * {pfx-a => pfx-b}sfx
-	 * pfx{sfx-a => sfx-b}
-	 * name-a => name-b
-	 */
-	if (pfx_length + sfx_length) {
-		name = xmalloc(len_a + len_b - pfx_length - sfx_length + 7);
-		sprintf(name, "%.*s{%.*s => %.*s}%s",
-			pfx_length, a,
-			len_a - pfx_length - sfx_length, a + pfx_length,
-			len_b - pfx_length - sfx_length, b + pfx_length,
-			a + len_a - sfx_length);
-	}
-	else {
-		name = xmalloc(len_a + len_b + 5);
-		sprintf(name, "%s => %s", a, b);
-	}
-	return name;
-}
-
-struct diffstat_t {
-	struct xdiff_emit_state xm;
-
-	int nr;
-	int alloc;
-	struct diffstat_file {
-		char *name;
-		unsigned is_unmerged:1;
-		unsigned is_binary:1;
-		unsigned is_renamed:1;
-		unsigned int added, deleted;
-	} **files;
-};
-
-static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
-					  const char *name_a,
-					  const char *name_b)
-{
-	struct diffstat_file *x;
-	x = xcalloc(sizeof (*x), 1);
-	if (diffstat->nr == diffstat->alloc) {
-		diffstat->alloc = alloc_nr(diffstat->alloc);
-		diffstat->files = xrealloc(diffstat->files,
-				diffstat->alloc * sizeof(x));
-	}
-	diffstat->files[diffstat->nr++] = x;
-	if (name_b) {
-		x->name = pprint_rename(name_a, name_b);
-		x->is_renamed = 1;
-	}
-	else
-		x->name = strdup(name_a);
-	return x;
-}
-
-static void diffstat_consume(void *priv, char *line, unsigned long len)
-{
-	struct diffstat_t *diffstat = priv;
-	struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
-
-	if (line[0] == '+')
-		x->added++;
-	else if (line[0] == '-')
-		x->deleted++;
-}
-
-static const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
-static const char minuses[]= "----------------------------------------------------------------------";
-
-static void show_stats(struct diffstat_t* data)
-{
-	char *prefix = "";
-	int i, len, add, del, total, adds = 0, dels = 0;
-	int max, max_change = 0, max_len = 0;
-	int total_files = data->nr;
-
-	if (data->nr == 0)
-		return;
-
-	for (i = 0; i < data->nr; i++) {
-		struct diffstat_file *file = data->files[i];
-
-		len = strlen(file->name);
-		if (max_len < len)
-			max_len = len;
+	for (i = 0; i < entries; i++) {
+		struct stat st;
+		unsigned int oldmode, newmode;
+		struct cache_entry *ce = active_cache[i];
+		int changed;
 
-		if (file->is_binary || file->is_unmerged)
+		if (!ce_path_match(ce, revs->prune_data))
 			continue;
-		if (max_change < file->added + file->deleted)
-			max_change = file->added + file->deleted;
-	}
 
-	for (i = 0; i < data->nr; i++) {
-		char *name = data->files[i]->name;
-		int added = data->files[i]->added;
-		int deleted = data->files[i]->deleted;
+		if (ce_stage(ce)) {
+			struct {
+				struct combine_diff_path p;
+				struct combine_diff_parent filler[5];
+			} combine;
+			int num_compare_stages = 0;
+
+			combine.p.next = NULL;
+			combine.p.len = ce_namelen(ce);
+			combine.p.path = xmalloc(combine.p.len + 1);
+			memcpy(combine.p.path, ce->name, combine.p.len);
+			combine.p.path[combine.p.len] = 0;
+			combine.p.mode = 0;
+			memset(combine.p.sha1, 0, 20);
+			memset(&combine.p.parent[0], 0,
+			       sizeof(combine.filler));
+
+			while (i < entries) {
+				struct cache_entry *nce = active_cache[i];
+				int stage;
+
+				if (strcmp(ce->name, nce->name))
+					break;
+
+				/* Stage #2 (ours) is the first parent,
+				 * stage #3 (theirs) is the second.
+				 */
+				stage = ce_stage(nce);
+				if (2 <= stage) {
+					int mode = ntohl(nce->ce_mode);
+					num_compare_stages++;
+					memcpy(combine.p.parent[stage-2].sha1,
+					       nce->sha1, 20);
+					combine.p.parent[stage-2].mode =
+						canon_mode(mode);
+					combine.p.parent[stage-2].status =
+						DIFF_STATUS_MODIFIED;
+				}
+
+				/* diff against the proper unmerged stage */
+				if (stage == diff_unmerged_stage)
+					ce = nce;
+				i++;
+			}
+			/*
+			 * Compensate for loop update
+			 */
+			i--;
 
-		if (0 < (len = quote_c_style(name, NULL, NULL, 0))) {
-			char *qname = xmalloc(len + 1);
-			quote_c_style(name, qname, NULL, 0);
-			free(name);
-			data->files[i]->name = name = qname;
-		}
+			if (revs->combine_merges && num_compare_stages == 2) {
+				show_combined_diff(&combine.p, 2,
+						   revs->dense_combined_merges,
+						   revs);
+				free(combine.p.path);
+				continue;
+			}
+			free(combine.p.path);
 
-		/*
-		 * "scale" the filename
-		 */
-		len = strlen(name);
-		max = max_len;
-		if (max > 50)
-			max = 50;
-		if (len > max) {
-			char *slash;
-			prefix = "...";
-			max -= 3;
-			name += len - max;
-			slash = strchr(name, '/');
-			if (slash)
-				name = slash;
+			/*
+			 * Show the diff for the 'ce' if we found the one
+			 * from the desired stage.
+			 */
+			diff_unmerge(&revs->diffopt, ce->name);
+			if (ce_stage(ce) != diff_unmerged_stage)
+				continue;
 		}
-		len = max;
 
-		/*
-		 * scale the add/delete
-		 */
-		max = max_change;
-		if (max + len > 70)
-			max = 70 - len;
-
-		if (data->files[i]->is_binary) {
-			printf(" %s%-*s |  Bin\n", prefix, len, name);
-			goto free_diffstat_file;
-		}
-		else if (data->files[i]->is_unmerged) {
-			printf(" %s%-*s |  Unmerged\n", prefix, len, name);
-			goto free_diffstat_file;
-		}
-		else if (!data->files[i]->is_renamed &&
-			 (added + deleted == 0)) {
-			total_files--;
-			goto free_diffstat_file;
+		if (lstat(ce->name, &st) < 0) {
+			if (errno != ENOENT && errno != ENOTDIR) {
+				perror(ce->name);
+				continue;
+			}
+			if (silent_on_removed)
+				continue;
+			diff_addremove(&revs->diffopt, '-', ntohl(ce->ce_mode),
+				       ce->sha1, ce->name, NULL);
+			continue;
 		}
+		changed = ce_match_stat(ce, &st, 0);
+		if (!changed && !revs->diffopt.find_copies_harder)
+			continue;
+		oldmode = ntohl(ce->ce_mode);
 
-		add = added;
-		del = deleted;
-		total = add + del;
-		adds += add;
-		dels += del;
+		newmode = canon_mode(st.st_mode);
+		if (!trust_executable_bit &&
+		    S_ISREG(newmode) && S_ISREG(oldmode) &&
+		    ((newmode ^ oldmode) == 0111))
+			newmode = oldmode;
+		diff_change(&revs->diffopt, oldmode, newmode,
+			    ce->sha1, (changed ? null_sha1 : ce->sha1),
+			    ce->name, NULL);
 
-		if (max_change > 0) {
-			total = (total * max + max_change / 2) / max_change;
-			add = (add * max + max_change / 2) / max_change;
-			del = total - add;
-		}
-		printf(" %s%-*s |%5d %.*s%.*s\n", prefix,
-				len, name, added + deleted,
-				add, pluses, del, minuses);
-	free_diffstat_file:
-		free(data->files[i]->name);
-		free(data->files[i]);
 	}
-	free(data->files);
-	printf(" %d files changed, %d insertions(+), %d deletions(-)\n",
-			total_files, adds, dels);
-}
-
-#define FIRST_FEW_BYTES 8000
-static int mmfile_is_binary(mmfile_t *mf)
-{
-	long sz = mf->size;
-	if (FIRST_FEW_BYTES < sz)
-		sz = FIRST_FEW_BYTES;
-	if (memchr(mf->ptr, 0, sz))
-		return 1;
+	diffcore_std(&revs->diffopt);
+	diff_flush(&revs->diffopt);
 	return 0;
 }
 
-static void builtin_diff(const char *name_a,
-			 const char *name_b,
-			 struct diff_filespec *one,
-			 struct diff_filespec *two,
-			 const char *xfrm_msg,
-			 int complete_rewrite)
-{
-	mmfile_t mf1, mf2;
-	const char *lbl[2];
-	char *a_one, *b_two;
-
-	a_one = quote_two("a/", name_a);
-	b_two = quote_two("b/", name_b);
-	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
-	lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-	printf("diff --git %s %s\n", a_one, b_two);
-	if (lbl[0][0] == '/') {
-		/* /dev/null */
-		printf("new file mode %06o\n", two->mode);
-		if (xfrm_msg && xfrm_msg[0])
-			puts(xfrm_msg);
-	}
-	else if (lbl[1][0] == '/') {
-		printf("deleted file mode %06o\n", one->mode);
-		if (xfrm_msg && xfrm_msg[0])
-			puts(xfrm_msg);
-	}
-	else {
-		if (one->mode != two->mode) {
-			printf("old mode %06o\n", one->mode);
-			printf("new mode %06o\n", two->mode);
-		}
-		if (xfrm_msg && xfrm_msg[0])
-			puts(xfrm_msg);
-		/*
-		 * we do not run diff between different kind
-		 * of objects.
-		 */
-		if ((one->mode ^ two->mode) & S_IFMT)
-			goto free_ab_and_return;
-		if (complete_rewrite) {
-			emit_rewrite_diff(name_a, name_b, one, two);
-			goto free_ab_and_return;
-		}
-	}
-
-	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-		die("unable to read files to diff");
-
-	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
-		printf("Binary files %s and %s differ\n", lbl[0], lbl[1]);
-	else {
-		/* Crazy xdl interfaces.. */
-		const char *diffopts = getenv("GIT_DIFF_OPTS");
-		xpparam_t xpp;
-		xdemitconf_t xecfg;
-		xdemitcb_t ecb;
-		struct emit_callback ecbdata;
-
-		ecbdata.label_path = lbl;
-		xpp.flags = XDF_NEED_MINIMAL;
-		xecfg.ctxlen = 3;
-		xecfg.flags = XDL_EMIT_FUNCNAMES;
-		if (!diffopts)
-			;
-		else if (!strncmp(diffopts, "--unified=", 10))
-			xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
-		else if (!strncmp(diffopts, "-u", 2))
-			xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
-		ecb.outf = fn_out;
-		ecb.priv = &ecbdata;
-		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
-	}
-
- free_ab_and_return:
-	free(a_one);
-	free(b_two);
-	return;
-}
-
-static void builtin_diffstat(const char *name_a, const char *name_b,
-			     struct diff_filespec *one,
-			     struct diff_filespec *two,
-			     struct diffstat_t *diffstat)
-{
-	mmfile_t mf1, mf2;
-	struct diffstat_file *data;
-
-	data = diffstat_add(diffstat, name_a, name_b);
-
-	if (!one || !two) {
-		data->is_unmerged = 1;
-		return;
-	}
-
-	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-		die("unable to read files to diff");
-
-	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
-		data->is_binary = 1;
-	else {
-		/* Crazy xdl interfaces.. */
-		xpparam_t xpp;
-		xdemitconf_t xecfg;
-		xdemitcb_t ecb;
-
-		xpp.flags = XDF_NEED_MINIMAL;
-		xecfg.ctxlen = 0;
-		xecfg.flags = 0;
-		ecb.outf = xdiff_outf;
-		ecb.priv = diffstat;
-		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
-	}
-}
-
-struct diff_filespec *alloc_filespec(const char *path)
-{
-	int namelen = strlen(path);
-	struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
-
-	memset(spec, 0, sizeof(*spec));
-	spec->path = (char *)(spec + 1);
-	memcpy(spec->path, path, namelen+1);
-	return spec;
-}
-
-void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
-		   unsigned short mode)
-{
-	if (mode) {
-		spec->mode = canon_mode(mode);
-		memcpy(spec->sha1, sha1, 20);
-		spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
-	}
-}
-
 /*
- * Given a name and sha1 pair, if the dircache tells us the file in
- * the work tree has that object contents, return true, so that
- * prepare_temp_file() does not have to inflate and extract.
+ * diff-index
  */
-static int work_tree_matches(const char *name, const unsigned char *sha1)
-{
-	struct cache_entry *ce;
-	struct stat st;
-	int pos, len;
-
-	/* We do not read the cache ourselves here, because the
-	 * benchmark with my previous version that always reads cache
-	 * shows that it makes things worse for diff-tree comparing
-	 * two linux-2.6 kernel trees in an already checked out work
-	 * tree.  This is because most diff-tree comparisons deal with
-	 * only a small number of files, while reading the cache is
-	 * expensive for a large project, and its cost outweighs the
-	 * savings we get by not inflating the object to a temporary
-	 * file.  Practically, this code only helps when we are used
-	 * by diff-cache --cached, which does read the cache before
-	 * calling us.
-	 */
-	if (!active_cache)
-		return 0;
 
-	len = strlen(name);
-	pos = cache_name_pos(name, len);
-	if (pos < 0)
-		return 0;
-	ce = active_cache[pos];
-	if ((lstat(name, &st) < 0) ||
-	    !S_ISREG(st.st_mode) || /* careful! */
-	    ce_match_stat(ce, &st, 0) ||
-	    memcmp(sha1, ce->sha1, 20))
-		return 0;
-	/* we return 1 only when we can stat, it is a regular file,
-	 * stat information matches, and sha1 recorded in the cache
-	 * matches.  I.e. we know the file in the work tree really is
-	 * the same as the <name, sha1> pair.
-	 */
-	return 1;
-}
-
-static struct sha1_size_cache {
-	unsigned char sha1[20];
-	unsigned long size;
-} **sha1_size_cache;
-static int sha1_size_cache_nr, sha1_size_cache_alloc;
-
-static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
-						 int find_only,
-						 unsigned long size)
+/* A file entry went away or appeared */
+static void diff_index_show_file(struct rev_info *revs,
+				 const char *prefix,
+				 struct cache_entry *ce,
+				 unsigned char *sha1, unsigned int mode)
 {
-	int first, last;
-	struct sha1_size_cache *e;
-
-	first = 0;
-	last = sha1_size_cache_nr;
-	while (last > first) {
-		int cmp, next = (last + first) >> 1;
-		e = sha1_size_cache[next];
-		cmp = memcmp(e->sha1, sha1, 20);
-		if (!cmp)
-			return e;
-		if (cmp < 0) {
-			last = next;
-			continue;
-		}
-		first = next+1;
-	}
-	/* not found */
-	if (find_only)
-		return NULL;
-	/* insert to make it at "first" */
-	if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
-		sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
-		sha1_size_cache = xrealloc(sha1_size_cache,
-					   sha1_size_cache_alloc *
-					   sizeof(*sha1_size_cache));
-	}
-	sha1_size_cache_nr++;
-	if (first < sha1_size_cache_nr)
-		memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
-			(sha1_size_cache_nr - first - 1) *
-			sizeof(*sha1_size_cache));
-	e = xmalloc(sizeof(struct sha1_size_cache));
-	sha1_size_cache[first] = e;
-	memcpy(e->sha1, sha1, 20);
-	e->size = size;
-	return e;
+	diff_addremove(&revs->diffopt, prefix[0], ntohl(mode),
+		       sha1, ce->name, NULL);
 }
 
-/*
- * While doing rename detection and pickaxe operation, we may need to
- * grab the data for the blob (or file) for our own in-core comparison.
- * diff_filespec has data and size fields for this purpose.
- */
-int diff_populate_filespec(struct diff_filespec *s, int size_only)
+static int get_stat_data(struct cache_entry *ce,
+			 unsigned char **sha1p,
+			 unsigned int *modep,
+			 int cached, int match_missing)
 {
-	int err = 0;
-	if (!DIFF_FILE_VALID(s))
-		die("internal error: asking to populate invalid file.");
-	if (S_ISDIR(s->mode))
-		return -1;
-
-	if (!use_size_cache)
-		size_only = 0;
+	unsigned char *sha1 = ce->sha1;
+	unsigned int mode = ce->ce_mode;
 
-	if (s->data)
-		return err;
-	if (!s->sha1_valid ||
-	    work_tree_matches(s->path, s->sha1)) {
+	if (!cached) {
+		static unsigned char no_sha1[20];
+		int changed;
 		struct stat st;
-		int fd;
-		if (lstat(s->path, &st) < 0) {
-			if (errno == ENOENT) {
-			err_empty:
-				err = -1;
-			empty:
-				s->data = "";
-				s->size = 0;
-				return err;
-			}
-		}
-		s->size = st.st_size;
-		if (!s->size)
-			goto empty;
-		if (size_only)
-			return 0;
-		if (S_ISLNK(st.st_mode)) {
-			int ret;
-			s->data = xmalloc(s->size);
-			s->should_free = 1;
-			ret = readlink(s->path, s->data, s->size);
-			if (ret < 0) {
-				free(s->data);
-				goto err_empty;
-			}
-			return 0;
-		}
-		fd = open(s->path, O_RDONLY);
-		if (fd < 0)
-			goto err_empty;
-		s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
-		close(fd);
-		if (s->data == MAP_FAILED)
-			goto err_empty;
-		s->should_munmap = 1;
-	}
-	else {
-		char type[20];
-		struct sha1_size_cache *e;
-
-		if (size_only) {
-			e = locate_size_cache(s->sha1, 1, 0);
-			if (e) {
-				s->size = e->size;
+		if (lstat(ce->name, &st) < 0) {
+			if (errno == ENOENT && match_missing) {
+				*sha1p = sha1;
+				*modep = mode;
 				return 0;
 			}
-			if (!sha1_object_info(s->sha1, type, &s->size))
-				locate_size_cache(s->sha1, 0, s->size);
-		}
-		else {
-			s->data = read_sha1_file(s->sha1, type, &s->size);
-			s->should_free = 1;
-		}
-	}
-	return 0;
-}
-
-void diff_free_filespec_data(struct diff_filespec *s)
-{
-	if (s->should_free)
-		free(s->data);
-	else if (s->should_munmap)
-		munmap(s->data, s->size);
-	s->should_free = s->should_munmap = 0;
-	s->data = NULL;
-	free(s->cnt_data);
-	s->cnt_data = NULL;
-}
-
-static void prep_temp_blob(struct diff_tempfile *temp,
-			   void *blob,
-			   unsigned long size,
-			   const unsigned char *sha1,
-			   int mode)
-{
-	int fd;
-
-	fd = git_mkstemp(temp->tmp_path, TEMPFILE_PATH_LEN, ".diff_XXXXXX");
-	if (fd < 0)
-		die("unable to create temp-file");
-	if (write(fd, blob, size) != size)
-		die("unable to write temp-file");
-	close(fd);
-	temp->name = temp->tmp_path;
-	strcpy(temp->hex, sha1_to_hex(sha1));
-	temp->hex[40] = 0;
-	sprintf(temp->mode, "%06o", mode);
-}
-
-static void prepare_temp_file(const char *name,
-			      struct diff_tempfile *temp,
-			      struct diff_filespec *one)
-{
-	if (!DIFF_FILE_VALID(one)) {
-	not_a_valid_file:
-		/* A '-' entry produces this for file-2, and
-		 * a '+' entry produces this for file-1.
-		 */
-		temp->name = "/dev/null";
-		strcpy(temp->hex, ".");
-		strcpy(temp->mode, ".");
-		return;
-	}
-
-	if (!one->sha1_valid ||
-	    work_tree_matches(name, one->sha1)) {
-		struct stat st;
-		if (lstat(name, &st) < 0) {
-			if (errno == ENOENT)
-				goto not_a_valid_file;
-			die("stat(%s): %s", name, strerror(errno));
-		}
-		if (S_ISLNK(st.st_mode)) {
-			int ret;
-			char buf[PATH_MAX + 1]; /* ought to be SYMLINK_MAX */
-			if (sizeof(buf) <= st.st_size)
-				die("symlink too long: %s", name);
-			ret = readlink(name, buf, st.st_size);
-			if (ret < 0)
-				die("readlink(%s)", name);
-			prep_temp_blob(temp, buf, st.st_size,
-				       (one->sha1_valid ?
-					one->sha1 : null_sha1),
-				       (one->sha1_valid ?
-					one->mode : S_IFLNK));
+			return -1;
 		}
-		else {
-			/* we can borrow from the file in the work tree */
-			temp->name = name;
-			if (!one->sha1_valid)
-				strcpy(temp->hex, sha1_to_hex(null_sha1));
-			else
-				strcpy(temp->hex, sha1_to_hex(one->sha1));
-			/* Even though we may sometimes borrow the
-			 * contents from the work tree, we always want
-			 * one->mode.  mode is trustworthy even when
-			 * !(one->sha1_valid), as long as
-			 * DIFF_FILE_VALID(one).
-			 */
-			sprintf(temp->mode, "%06o", one->mode);
+		changed = ce_match_stat(ce, &st, 0);
+		if (changed) {
+			mode = create_ce_mode(st.st_mode);
+			if (!trust_executable_bit && S_ISREG(st.st_mode))
+				mode = ce->ce_mode;
+			sha1 = no_sha1;
 		}
-		return;
 	}
-	else {
-		if (diff_populate_filespec(one, 0))
-			die("cannot read data blob for %s", one->path);
-		prep_temp_blob(temp, one->data, one->size,
-			       one->sha1, one->mode);
-	}
-}
 
-static void remove_tempfile(void)
-{
-	int i;
-
-	for (i = 0; i < 2; i++)
-		if (diff_temp[i].name == diff_temp[i].tmp_path) {
-			unlink(diff_temp[i].name);
-			diff_temp[i].name = NULL;
-		}
-}
-
-static void remove_tempfile_on_signal(int signo)
-{
-	remove_tempfile();
-	signal(SIGINT, SIG_DFL);
-	raise(signo);
+	*sha1p = sha1;
+	*modep = mode;
+	return 0;
 }
 
-static int spawn_prog(const char *pgm, const char **arg)
+static void show_new_file(struct rev_info *revs,
+			  struct cache_entry *new,
+			  int cached, int match_missing)
 {
-	pid_t pid;
-	int status;
-
-	fflush(NULL);
-	pid = fork();
-	if (pid < 0)
-		die("unable to fork");
-	if (!pid) {
-		execvp(pgm, (char *const*) arg);
-		exit(255);
-	}
-
-	while (waitpid(pid, &status, 0) < 0) {
-		if (errno == EINTR)
-			continue;
-		return -1;
-	}
+	unsigned char *sha1;
+	unsigned int mode;
 
-	/* Earlier we did not check the exit status because
-	 * diff exits non-zero if files are different, and
-	 * we are not interested in knowing that.  It was a
-	 * mistake which made it harder to quit a diff-*
-	 * session that uses the git-apply-patch-script as
-	 * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
-	 * should also exit non-zero only when it wants to
-	 * abort the entire diff-* session.
+	/* New file in the index: it might actually be different in
+	 * the working copy.
 	 */
-	if (WIFEXITED(status) && !WEXITSTATUS(status))
-		return 0;
-	return -1;
-}
-
-/* An external diff command takes:
- *
- * diff-cmd name infile1 infile1-sha1 infile1-mode \
- *               infile2 infile2-sha1 infile2-mode [ rename-to ]
- *
- */
-static void run_external_diff(const char *pgm,
-			      const char *name,
-			      const char *other,
-			      struct diff_filespec *one,
-			      struct diff_filespec *two,
-			      const char *xfrm_msg,
-			      int complete_rewrite)
-{
-	const char *spawn_arg[10];
-	struct diff_tempfile *temp = diff_temp;
-	int retval;
-	static int atexit_asked = 0;
-	const char *othername;
-	const char **arg = &spawn_arg[0];
-
-	othername = (other? other : name);
-	if (one && two) {
-		prepare_temp_file(name, &temp[0], one);
-		prepare_temp_file(othername, &temp[1], two);
-		if (! atexit_asked &&
-		    (temp[0].name == temp[0].tmp_path ||
-		     temp[1].name == temp[1].tmp_path)) {
-			atexit_asked = 1;
-			atexit(remove_tempfile);
-		}
-		signal(SIGINT, remove_tempfile_on_signal);
-	}
-
-	if (one && two) {
-		*arg++ = pgm;
-		*arg++ = name;
-		*arg++ = temp[0].name;
-		*arg++ = temp[0].hex;
-		*arg++ = temp[0].mode;
-		*arg++ = temp[1].name;
-		*arg++ = temp[1].hex;
-		*arg++ = temp[1].mode;
-		if (other) {
-			*arg++ = other;
-			*arg++ = xfrm_msg;
-		}
-	} else {
-		*arg++ = pgm;
-		*arg++ = name;
-	}
-	*arg = NULL;
-	retval = spawn_prog(pgm, spawn_arg);
-	remove_tempfile();
-	if (retval) {
-		fprintf(stderr, "external diff died, stopping at %s.\n", name);
-		exit(1);
-	}
-}
-
-static void run_diff_cmd(const char *pgm,
-			 const char *name,
-			 const char *other,
-			 struct diff_filespec *one,
-			 struct diff_filespec *two,
-			 const char *xfrm_msg,
-			 int complete_rewrite)
-{
-	if (pgm) {
-		run_external_diff(pgm, name, other, one, two, xfrm_msg,
-				  complete_rewrite);
+	if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
 		return;
-	}
-	if (one && two)
-		builtin_diff(name, other ? other : name,
-			     one, two, xfrm_msg, complete_rewrite);
-	else
-		printf("* Unmerged path %s\n", name);
-}
 
-static void diff_fill_sha1_info(struct diff_filespec *one)
-{
-	if (DIFF_FILE_VALID(one)) {
-		if (!one->sha1_valid) {
-			struct stat st;
-			if (lstat(one->path, &st) < 0)
-				die("stat %s", one->path);
-			if (index_path(one->sha1, one->path, &st, 0))
-				die("cannot hash %s\n", one->path);
-		}
-	}
-	else
-		memset(one->sha1, 0, 20);
+	diff_index_show_file(revs, "+", new, sha1, mode);
 }
 
-static void run_diff(struct diff_filepair *p, struct diff_options *o)
+static int show_modified(struct rev_info *revs,
+			 struct cache_entry *old,
+			 struct cache_entry *new,
+			 int report_missing,
+			 int cached, int match_missing)
 {
-	const char *pgm = external_diff();
-	char msg[PATH_MAX*2+300], *xfrm_msg;
-	struct diff_filespec *one;
-	struct diff_filespec *two;
-	const char *name;
-	const char *other;
-	char *name_munged, *other_munged;
-	int complete_rewrite = 0;
-	int len;
-
-	if (DIFF_PAIR_UNMERGED(p)) {
-		/* unmerged */
-		run_diff_cmd(pgm, p->one->path, NULL, NULL, NULL, NULL, 0);
-		return;
-	}
-
-	name = p->one->path;
-	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
-	name_munged = quote_one(name);
-	other_munged = quote_one(other);
-	one = p->one; two = p->two;
-
-	diff_fill_sha1_info(one);
-	diff_fill_sha1_info(two);
-
-	len = 0;
-	switch (p->status) {
-	case DIFF_STATUS_COPIED:
-		len += snprintf(msg + len, sizeof(msg) - len,
-				"similarity index %d%%\n"
-				"copy from %s\n"
-				"copy to %s\n",
-				(int)(0.5 + p->score * 100.0/MAX_SCORE),
-				name_munged, other_munged);
-		break;
-	case DIFF_STATUS_RENAMED:
-		len += snprintf(msg + len, sizeof(msg) - len,
-				"similarity index %d%%\n"
-				"rename from %s\n"
-				"rename to %s\n",
-				(int)(0.5 + p->score * 100.0/MAX_SCORE),
-				name_munged, other_munged);
-		break;
-	case DIFF_STATUS_MODIFIED:
-		if (p->score) {
-			len += snprintf(msg + len, sizeof(msg) - len,
-					"dissimilarity index %d%%\n",
-					(int)(0.5 + p->score *
-					      100.0/MAX_SCORE));
-			complete_rewrite = 1;
-			break;
-		}
-		/* fallthru */
-	default:
-		/* nothing */
-		;
-	}
-
-	if (memcmp(one->sha1, two->sha1, 20)) {
-		char one_sha1[41];
-		int abbrev = o->full_index ? 40 : DEFAULT_ABBREV;
-		memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
-
-		len += snprintf(msg + len, sizeof(msg) - len,
-				"index %.*s..%.*s",
-				abbrev, one_sha1, abbrev,
-				sha1_to_hex(two->sha1));
-		if (one->mode == two->mode)
-			len += snprintf(msg + len, sizeof(msg) - len,
-					" %06o", one->mode);
-		len += snprintf(msg + len, sizeof(msg) - len, "\n");
-	}
-
-	if (len)
-		msg[--len] = 0;
-	xfrm_msg = len ? msg : NULL;
+	unsigned int mode, oldmode;
+	unsigned char *sha1;
 
-	if (!pgm &&
-	    DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
-	    (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
-		/* a filepair that changes between file and symlink
-		 * needs to be split into deletion and creation.
-		 */
-		struct diff_filespec *null = alloc_filespec(two->path);
-		run_diff_cmd(NULL, name, other, one, null, xfrm_msg, 0);
-		free(null);
-		null = alloc_filespec(one->path);
-		run_diff_cmd(NULL, name, other, null, two, xfrm_msg, 0);
-		free(null);
-	}
-	else
-		run_diff_cmd(pgm, name, other, one, two, xfrm_msg,
-			     complete_rewrite);
-
-	free(name_munged);
-	free(other_munged);
-}
-
-static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
-			 struct diffstat_t *diffstat)
-{
-	const char *name;
-	const char *other;
-
-	if (DIFF_PAIR_UNMERGED(p)) {
-		/* unmerged */
-		builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat);
-		return;
-	}
-
-	name = p->one->path;
-	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
-
-	diff_fill_sha1_info(p->one);
-	diff_fill_sha1_info(p->two);
-
-	builtin_diffstat(name, other, p->one, p->two, diffstat);
-}
-
-void diff_setup(struct diff_options *options)
-{
-	memset(options, 0, sizeof(*options));
-	options->output_format = DIFF_FORMAT_RAW;
-	options->line_termination = '\n';
-	options->break_opt = -1;
-	options->rename_limit = -1;
-
-	options->change = diff_change;
-	options->add_remove = diff_addremove;
-}
-
-int diff_setup_done(struct diff_options *options)
-{
-	if ((options->find_copies_harder &&
-	     options->detect_rename != DIFF_DETECT_COPY) ||
-	    (0 <= options->rename_limit && !options->detect_rename))
+	if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
+		if (report_missing)
+			diff_index_show_file(revs, "-", old,
+					     old->sha1, old->ce_mode);
 		return -1;
-
-	/*
-	 * These cases always need recursive; we do not drop caller-supplied
-	 * recursive bits for other formats here.
-	 */
-	if ((options->output_format == DIFF_FORMAT_PATCH) ||
-	    (options->output_format == DIFF_FORMAT_DIFFSTAT))
-		options->recursive = 1;
-
-	if (options->detect_rename && options->rename_limit < 0)
-		options->rename_limit = diff_rename_limit_default;
-	if (options->setup & DIFF_SETUP_USE_CACHE) {
-		if (!active_cache)
-			/* read-cache does not die even when it fails
-			 * so it is safe for us to do this here.  Also
-			 * it does not smudge active_cache or active_nr
-			 * when it fails, so we do not have to worry about
-			 * cleaning it up ourselves either.
-			 */
-			read_cache();
 	}
-	if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
-		use_size_cache = 1;
-	if (options->abbrev <= 0 || 40 < options->abbrev)
-		options->abbrev = 40; /* full */
-
-	return 0;
-}
 
-int diff_opt_parse(struct diff_options *options, const char **av, int ac)
-{
-	const char *arg = av[0];
-	if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
-		options->output_format = DIFF_FORMAT_PATCH;
-	else if (!strcmp(arg, "--patch-with-raw")) {
-		options->output_format = DIFF_FORMAT_PATCH;
-		options->with_raw = 1;
-	}
-	else if (!strcmp(arg, "--stat"))
-		options->output_format = DIFF_FORMAT_DIFFSTAT;
-	else if (!strcmp(arg, "--patch-with-stat")) {
-		options->output_format = DIFF_FORMAT_PATCH;
-		options->with_stat = 1;
-	}
-	else if (!strcmp(arg, "-z"))
-		options->line_termination = 0;
-	else if (!strncmp(arg, "-l", 2))
-		options->rename_limit = strtoul(arg+2, NULL, 10);
-	else if (!strcmp(arg, "--full-index"))
-		options->full_index = 1;
-	else if (!strcmp(arg, "--name-only"))
-		options->output_format = DIFF_FORMAT_NAME;
-	else if (!strcmp(arg, "--name-status"))
-		options->output_format = DIFF_FORMAT_NAME_STATUS;
-	else if (!strcmp(arg, "-R"))
-		options->reverse_diff = 1;
-	else if (!strncmp(arg, "-S", 2))
-		options->pickaxe = arg + 2;
-	else if (!strcmp(arg, "-s"))
-		options->output_format = DIFF_FORMAT_NO_OUTPUT;
-	else if (!strncmp(arg, "-O", 2))
-		options->orderfile = arg + 2;
-	else if (!strncmp(arg, "--diff-filter=", 14))
-		options->filter = arg + 14;
-	else if (!strcmp(arg, "--pickaxe-all"))
-		options->pickaxe_opts = DIFF_PICKAXE_ALL;
-	else if (!strcmp(arg, "--pickaxe-regex"))
-		options->pickaxe_opts = DIFF_PICKAXE_REGEX;
-	else if (!strncmp(arg, "-B", 2)) {
-		if ((options->break_opt =
-		     diff_scoreopt_parse(arg)) == -1)
-			return -1;
-	}
-	else if (!strncmp(arg, "-M", 2)) {
-		if ((options->rename_score =
-		     diff_scoreopt_parse(arg)) == -1)
-			return -1;
-		options->detect_rename = DIFF_DETECT_RENAME;
-	}
-	else if (!strncmp(arg, "-C", 2)) {
-		if ((options->rename_score =
-		     diff_scoreopt_parse(arg)) == -1)
-			return -1;
-		options->detect_rename = DIFF_DETECT_COPY;
-	}
-	else if (!strcmp(arg, "--find-copies-harder"))
-		options->find_copies_harder = 1;
-	else if (!strcmp(arg, "--abbrev"))
-		options->abbrev = DEFAULT_ABBREV;
-	else if (!strncmp(arg, "--abbrev=", 9)) {
-		options->abbrev = strtoul(arg + 9, NULL, 10);
-		if (options->abbrev < MINIMUM_ABBREV)
-			options->abbrev = MINIMUM_ABBREV;
-		else if (40 < options->abbrev)
-			options->abbrev = 40;
-	}
-	else
+	oldmode = old->ce_mode;
+	if (mode == oldmode && !memcmp(sha1, old->sha1, 20) &&
+	    !revs->diffopt.find_copies_harder)
 		return 0;
-	return 1;
-}
-
-static int parse_num(const char **cp_p)
-{
-	unsigned long num, scale;
-	int ch, dot;
-	const char *cp = *cp_p;
-
-	num = 0;
-	scale = 1;
-	dot = 0;
-	for(;;) {
-		ch = *cp;
-		if ( !dot && ch == '.' ) {
-			scale = 1;
-			dot = 1;
-		} else if ( ch == '%' ) {
-			scale = dot ? scale*100 : 100;
-			cp++;	/* % is always at the end */
-			break;
-		} else if ( ch >= '0' && ch <= '9' ) {
-			if ( scale < 100000 ) {
-				scale *= 10;
-				num = (num*10) + (ch-'0');
-			}
-		} else {
-			break;
-		}
-		cp++;
-	}
-	*cp_p = cp;
-
-	/* user says num divided by scale and we say internally that
-	 * is MAX_SCORE * num / scale.
-	 */
-	return (num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale);
-}
-
-int diff_scoreopt_parse(const char *opt)
-{
-	int opt1, opt2, cmd;
-
-	if (*opt++ != '-')
-		return -1;
-	cmd = *opt++;
-	if (cmd != 'M' && cmd != 'C' && cmd != 'B')
-		return -1; /* that is not a -M, -C nor -B option */
-
-	opt1 = parse_num(&opt);
-	if (cmd != 'B')
-		opt2 = 0;
-	else {
-		if (*opt == 0)
-			opt2 = 0;
-		else if (*opt != '/')
-			return -1; /* we expect -B80/99 or -B80 */
-		else {
-			opt++;
-			opt2 = parse_num(&opt);
-		}
-	}
-	if (*opt != 0)
-		return -1;
-	return opt1 | (opt2 << 16);
-}
-
-struct diff_queue_struct diff_queued_diff;
-
-void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
-{
-	if (queue->alloc <= queue->nr) {
-		queue->alloc = alloc_nr(queue->alloc);
-		queue->queue = xrealloc(queue->queue,
-					sizeof(dp) * queue->alloc);
-	}
-	queue->queue[queue->nr++] = dp;
-}
-
-struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
-				 struct diff_filespec *one,
-				 struct diff_filespec *two)
-{
-	struct diff_filepair *dp = xmalloc(sizeof(*dp));
-	dp->one = one;
-	dp->two = two;
-	dp->score = 0;
-	dp->status = 0;
-	dp->source_stays = 0;
-	dp->broken_pair = 0;
-	if (queue)
-		diff_q(queue, dp);
-	return dp;
-}
-
-void diff_free_filepair(struct diff_filepair *p)
-{
-	diff_free_filespec_data(p->one);
-	diff_free_filespec_data(p->two);
-	free(p->one);
-	free(p->two);
-	free(p);
-}
-
-/* This is different from find_unique_abbrev() in that
- * it stuffs the result with dots for alignment.
- */
-const char *diff_unique_abbrev(const unsigned char *sha1, int len)
-{
-	int abblen;
-	const char *abbrev;
-	if (len == 40)
-		return sha1_to_hex(sha1);
-
-	abbrev = find_unique_abbrev(sha1, len);
-	if (!abbrev)
-		return sha1_to_hex(sha1);
-	abblen = strlen(abbrev);
-	if (abblen < 37) {
-		static char hex[41];
-		if (len < abblen && abblen <= len + 2)
-			sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
-		else
-			sprintf(hex, "%s...", abbrev);
-		return hex;
-	}
-	return sha1_to_hex(sha1);
-}
-
-static void diff_flush_raw(struct diff_filepair *p,
-			   int line_termination,
-			   int inter_name_termination,
-			   struct diff_options *options,
-			   int output_format)
-{
-	int two_paths;
-	char status[10];
-	int abbrev = options->abbrev;
-	const char *path_one, *path_two;
-
-	path_one = p->one->path;
-	path_two = p->two->path;
-	if (line_termination) {
-		path_one = quote_one(path_one);
-		path_two = quote_one(path_two);
-	}
-
-	if (p->score)
-		sprintf(status, "%c%03d", p->status,
-			(int)(0.5 + p->score * 100.0/MAX_SCORE));
-	else {
-		status[0] = p->status;
-		status[1] = 0;
-	}
-	switch (p->status) {
-	case DIFF_STATUS_COPIED:
-	case DIFF_STATUS_RENAMED:
-		two_paths = 1;
-		break;
-	case DIFF_STATUS_ADDED:
-	case DIFF_STATUS_DELETED:
-		two_paths = 0;
-		break;
-	default:
-		two_paths = 0;
-		break;
-	}
-	if (output_format != DIFF_FORMAT_NAME_STATUS) {
-		printf(":%06o %06o %s ",
-		       p->one->mode, p->two->mode,
-		       diff_unique_abbrev(p->one->sha1, abbrev));
-		printf("%s ",
-		       diff_unique_abbrev(p->two->sha1, abbrev));
-	}
-	printf("%s%c%s", status, inter_name_termination, path_one);
-	if (two_paths)
-		printf("%c%s", inter_name_termination, path_two);
-	putchar(line_termination);
-	if (path_one != p->one->path)
-		free((void*)path_one);
-	if (path_two != p->two->path)
-		free((void*)path_two);
-}
-
-static void diff_flush_name(struct diff_filepair *p,
-			    int inter_name_termination,
-			    int line_termination)
-{
-	char *path = p->two->path;
-
-	if (line_termination)
-		path = quote_one(p->two->path);
-	else
-		path = p->two->path;
-	printf("%s%c", path, line_termination);
-	if (p->two->path != path)
-		free(path);
-}
-
-int diff_unmodified_pair(struct diff_filepair *p)
-{
-	/* This function is written stricter than necessary to support
-	 * the currently implemented transformers, but the idea is to
-	 * let transformers to produce diff_filepairs any way they want,
-	 * and filter and clean them up here before producing the output.
-	 */
-	struct diff_filespec *one, *two;
 
-	if (DIFF_PAIR_UNMERGED(p))
-		return 0; /* unmerged is interesting */
+	mode = ntohl(mode);
+	oldmode = ntohl(oldmode);
 
-	one = p->one;
-	two = p->two;
-
-	/* deletion, addition, mode or type change
-	 * and rename are all interesting.
-	 */
-	if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
-	    DIFF_PAIR_MODE_CHANGED(p) ||
-	    strcmp(one->path, two->path))
-		return 0;
-
-	/* both are valid and point at the same path.  that is, we are
-	 * dealing with a change.
-	 */
-	if (one->sha1_valid && two->sha1_valid &&
-	    !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
-		return 1; /* no change */
-	if (!one->sha1_valid && !two->sha1_valid)
-		return 1; /* both look at the same file on the filesystem. */
+	diff_change(&revs->diffopt, oldmode, mode,
+		    old->sha1, sha1, old->name, NULL);
 	return 0;
 }
 
-static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
+static int diff_cache(struct rev_info *revs,
+		      struct cache_entry **ac, int entries,
+		      const char **pathspec,
+		      int cached, int match_missing)
 {
-	if (diff_unmodified_pair(p))
-		return;
+	while (entries) {
+		struct cache_entry *ce = *ac;
+		int same = (entries > 1) && ce_same_name(ce, ac[1]);
 
-	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
-	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
-		return; /* no tree diffs in patch format */
+		if (!ce_path_match(ce, pathspec))
+			goto skip_entry;
 
-	run_diff(p, o);
-}
-
-static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
-			    struct diffstat_t *diffstat)
-{
-	if (diff_unmodified_pair(p))
-		return;
-
-	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
-	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
-		return; /* no tree diffs in patch format */
-
-	run_diffstat(p, o, diffstat);
-}
-
-int diff_queue_is_empty(void)
-{
-	struct diff_queue_struct *q = &diff_queued_diff;
-	int i;
-	for (i = 0; i < q->nr; i++)
-		if (!diff_unmodified_pair(q->queue[i]))
-			return 0;
-	return 1;
-}
-
-#if DIFF_DEBUG
-void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
-{
-	fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
-		x, one ? one : "",
-		s->path,
-		DIFF_FILE_VALID(s) ? "valid" : "invalid",
-		s->mode,
-		s->sha1_valid ? sha1_to_hex(s->sha1) : "");
-	fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
-		x, one ? one : "",
-		s->size, s->xfrm_flags);
-}
-
-void diff_debug_filepair(const struct diff_filepair *p, int i)
-{
-	diff_debug_filespec(p->one, i, "one");
-	diff_debug_filespec(p->two, i, "two");
-	fprintf(stderr, "score %d, status %c stays %d broken %d\n",
-		p->score, p->status ? p->status : '?',
-		p->source_stays, p->broken_pair);
-}
-
-void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
-{
-	int i;
-	if (msg)
-		fprintf(stderr, "%s\n", msg);
-	fprintf(stderr, "q->nr = %d\n", q->nr);
-	for (i = 0; i < q->nr; i++) {
-		struct diff_filepair *p = q->queue[i];
-		diff_debug_filepair(p, i);
-	}
-}
-#endif
-
-static void diff_resolve_rename_copy(void)
-{
-	int i, j;
-	struct diff_filepair *p, *pp;
-	struct diff_queue_struct *q = &diff_queued_diff;
-
-	diff_debug_queue("resolve-rename-copy", q);
-
-	for (i = 0; i < q->nr; i++) {
-		p = q->queue[i];
-		p->status = 0; /* undecided */
-		if (DIFF_PAIR_UNMERGED(p))
-			p->status = DIFF_STATUS_UNMERGED;
-		else if (!DIFF_FILE_VALID(p->one))
-			p->status = DIFF_STATUS_ADDED;
-		else if (!DIFF_FILE_VALID(p->two))
-			p->status = DIFF_STATUS_DELETED;
-		else if (DIFF_PAIR_TYPE_CHANGED(p))
-			p->status = DIFF_STATUS_TYPE_CHANGED;
-
-		/* from this point on, we are dealing with a pair
-		 * whose both sides are valid and of the same type, i.e.
-		 * either in-place edit or rename/copy edit.
-		 */
-		else if (DIFF_PAIR_RENAME(p)) {
-			if (p->source_stays) {
-				p->status = DIFF_STATUS_COPIED;
-				continue;
+		switch (ce_stage(ce)) {
+		case 0:
+			/* No stage 1 entry? That means it's a new file */
+			if (!same) {
+				show_new_file(revs, ce, cached, match_missing);
+				break;
 			}
-			/* See if there is some other filepair that
-			 * copies from the same source as us.  If so
-			 * we are a copy.  Otherwise we are either a
-			 * copy if the path stays, or a rename if it
-			 * does not, but we already handled "stays" case.
+			/* Show difference between old and new */
+			show_modified(revs,ac[1], ce, 1,
+				      cached, match_missing);
+			break;
+		case 1:
+			/* No stage 3 (merge) entry?
+			 * That means it's been deleted.
 			 */
-			for (j = i + 1; j < q->nr; j++) {
-				pp = q->queue[j];
-				if (strcmp(pp->one->path, p->one->path))
-					continue; /* not us */
-				if (!DIFF_PAIR_RENAME(pp))
-					continue; /* not a rename/copy */
-				/* pp is a rename/copy from the same source */
-				p->status = DIFF_STATUS_COPIED;
+			if (!same) {
+				diff_index_show_file(revs, "-", ce,
+						     ce->sha1, ce->ce_mode);
 				break;
 			}
-			if (!p->status)
-				p->status = DIFF_STATUS_RENAMED;
-		}
-		else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
-			 p->one->mode != p->two->mode)
-			p->status = DIFF_STATUS_MODIFIED;
-		else {
-			/* This is a "no-change" entry and should not
-			 * happen anymore, but prepare for broken callers.
+			/* We come here with ce pointing at stage 1
+			 * (original tree) and ac[1] pointing at stage
+			 * 3 (unmerged).  show-modified with
+			 * report-missing set to false does not say the
+			 * file is deleted but reports true if work
+			 * tree does not have it, in which case we
+			 * fall through to report the unmerged state.
+			 * Otherwise, we show the differences between
+			 * the original tree and the work tree.
 			 */
-			error("feeding unmodified %s to diffcore",
-			      p->one->path);
-			p->status = DIFF_STATUS_UNKNOWN;
-		}
-	}
-	diff_debug_queue("resolve-rename-copy done", q);
-}
-
-static void flush_one_pair(struct diff_filepair *p,
-			   int diff_output_format,
-			   struct diff_options *options,
-			   struct diffstat_t *diffstat)
-{
-	int inter_name_termination = '\t';
-	int line_termination = options->line_termination;
-	if (!line_termination)
-		inter_name_termination = 0;
-
-	switch (p->status) {
-	case DIFF_STATUS_UNKNOWN:
-		break;
-	case 0:
-		die("internal error in diff-resolve-rename-copy");
-		break;
-	default:
-		switch (diff_output_format) {
-		case DIFF_FORMAT_DIFFSTAT:
-			diff_flush_stat(p, options, diffstat);
-			break;
-		case DIFF_FORMAT_PATCH:
-			diff_flush_patch(p, options);
-			break;
-		case DIFF_FORMAT_RAW:
-		case DIFF_FORMAT_NAME_STATUS:
-			diff_flush_raw(p, line_termination,
-				       inter_name_termination,
-				       options, diff_output_format);
-			break;
-		case DIFF_FORMAT_NAME:
-			diff_flush_name(p,
-					inter_name_termination,
-					line_termination);
-			break;
-		case DIFF_FORMAT_NO_OUTPUT:
+			if (!cached &&
+			    !show_modified(revs, ce, ac[1], 0,
+					   cached, match_missing))
+				break;
+			/* fallthru */
+		case 3:
+			diff_unmerge(&revs->diffopt, ce->name);
 			break;
-		}
-	}
-}
 
-void diff_flush(struct diff_options *options)
-{
-	struct diff_queue_struct *q = &diff_queued_diff;
-	int i;
-	int diff_output_format = options->output_format;
-	struct diffstat_t *diffstat = NULL;
-
-	if (diff_output_format == DIFF_FORMAT_DIFFSTAT || options->with_stat) {
-		diffstat = xcalloc(sizeof (struct diffstat_t), 1);
-		diffstat->xm.consume = diffstat_consume;
-	}
-
-	if (options->with_raw) {
-		for (i = 0; i < q->nr; i++) {
-			struct diff_filepair *p = q->queue[i];
-			flush_one_pair(p, DIFF_FORMAT_RAW, options, NULL);
-		}
-		putchar(options->line_termination);
-	}
-	if (options->with_stat) {
-		for (i = 0; i < q->nr; i++) {
-			struct diff_filepair *p = q->queue[i];
-			flush_one_pair(p, DIFF_FORMAT_DIFFSTAT, options,
-				       diffstat);
+		default:
+			die("impossible cache entry stage");
 		}
-		show_stats(diffstat);
-		free(diffstat);
-		diffstat = NULL;
-		putchar(options->line_termination);
-	}
-	for (i = 0; i < q->nr; i++) {
-		struct diff_filepair *p = q->queue[i];
-		flush_one_pair(p, diff_output_format, options, diffstat);
-		diff_free_filepair(p);
-	}
 
-	if (diffstat) {
-		show_stats(diffstat);
-		free(diffstat);
+skip_entry:
+		/*
+		 * Ignore all the different stages for this file,
+		 * we've handled the relevant cases now.
+		 */
+		do {
+			ac++;
+			entries--;
+		} while (entries && ce_same_name(ce, ac[0]));
 	}
-
-	free(q->queue);
-	q->queue = NULL;
-	q->nr = q->alloc = 0;
+	return 0;
 }
 
-static void diffcore_apply_filter(const char *filter)
+/*
+ * This turns all merge entries into "stage 3". That guarantees that
+ * when we read in the new tree (into "stage 1"), we won't lose sight
+ * of the fact that we had unmerged entries.
+ */
+static void mark_merge_entries(void)
 {
 	int i;
-	struct diff_queue_struct *q = &diff_queued_diff;
-	struct diff_queue_struct outq;
-	outq.queue = NULL;
-	outq.nr = outq.alloc = 0;
-
-	if (!filter)
-		return;
-
-	if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
-		int found;
-		for (i = found = 0; !found && i < q->nr; i++) {
-			struct diff_filepair *p = q->queue[i];
-			if (((p->status == DIFF_STATUS_MODIFIED) &&
-			     ((p->score &&
-			       strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
-			      (!p->score &&
-			       strchr(filter, DIFF_STATUS_MODIFIED)))) ||
-			    ((p->status != DIFF_STATUS_MODIFIED) &&
-			     strchr(filter, p->status)))
-				found++;
-		}
-		if (found)
-			return;
-
-		/* otherwise we will clear the whole queue
-		 * by copying the empty outq at the end of this
-		 * function, but first clear the current entries
-		 * in the queue.
-		 */
-		for (i = 0; i < q->nr; i++)
-			diff_free_filepair(q->queue[i]);
-	}
-	else {
-		/* Only the matching ones */
-		for (i = 0; i < q->nr; i++) {
-			struct diff_filepair *p = q->queue[i];
-
-			if (((p->status == DIFF_STATUS_MODIFIED) &&
-			     ((p->score &&
-			       strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
-			      (!p->score &&
-			       strchr(filter, DIFF_STATUS_MODIFIED)))) ||
-			    ((p->status != DIFF_STATUS_MODIFIED) &&
-			     strchr(filter, p->status)))
-				diff_q(&outq, p);
-			else
-				diff_free_filepair(p);
-		}
+	for (i = 0; i < active_nr; i++) {
+		struct cache_entry *ce = active_cache[i];
+		if (!ce_stage(ce))
+			continue;
+		ce->ce_flags |= htons(CE_STAGEMASK);
 	}
-	free(q->queue);
-	*q = outq;
-}
-
-void diffcore_std(struct diff_options *options)
-{
-	if (options->break_opt != -1)
-		diffcore_break(options->break_opt);
-	if (options->detect_rename)
-		diffcore_rename(options);
-	if (options->break_opt != -1)
-		diffcore_merge_broken();
-	if (options->pickaxe)
-		diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
-	if (options->orderfile)
-		diffcore_order(options->orderfile);
-	diff_resolve_rename_copy();
-	diffcore_apply_filter(options->filter);
-}
-
-
-void diffcore_std_no_resolve(struct diff_options *options)
-{
-	if (options->pickaxe)
-		diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
-	if (options->orderfile)
-		diffcore_order(options->orderfile);
-	diffcore_apply_filter(options->filter);
 }
 
-void diff_addremove(struct diff_options *options,
-		    int addremove, unsigned mode,
-		    const unsigned char *sha1,
-		    const char *base, const char *path)
+int run_diff_index(struct rev_info *revs, int cached)
 {
-	char concatpath[PATH_MAX];
-	struct diff_filespec *one, *two;
+	int ret;
+	struct object *ent;
+	struct tree *tree;
+	const char *tree_name;
+	int match_missing = 0;
 
-	/* This may look odd, but it is a preparation for
-	 * feeding "there are unchanged files which should
-	 * not produce diffs, but when you are doing copy
-	 * detection you would need them, so here they are"
-	 * entries to the diff-core.  They will be prefixed
-	 * with something like '=' or '*' (I haven't decided
-	 * which but should not make any difference).
-	 * Feeding the same new and old to diff_change() 
-	 * also has the same effect.
-	 * Before the final output happens, they are pruned after
-	 * merged into rename/copy pairs as appropriate.
+	/* 
+	 * Backward compatibility wart - "diff-index -m" does
+	 * not mean "do not ignore merges", but totally different.
 	 */
-	if (options->reverse_diff)
-		addremove = (addremove == '+' ? '-' :
-			     addremove == '-' ? '+' : addremove);
-
-	if (!path) path = "";
-	sprintf(concatpath, "%s%s", base, path);
-	one = alloc_filespec(concatpath);
-	two = alloc_filespec(concatpath);
-
-	if (addremove != '+')
-		fill_filespec(one, sha1, mode);
-	if (addremove != '-')
-		fill_filespec(two, sha1, mode);
+	if (!revs->ignore_merges)
+		match_missing = 1;
 
-	diff_queue(&diff_queued_diff, one, two);
-}
-
-void diff_change(struct diff_options *options,
-		 unsigned old_mode, unsigned new_mode,
-		 const unsigned char *old_sha1,
-		 const unsigned char *new_sha1,
-		 const char *base, const char *path) 
-{
-	char concatpath[PATH_MAX];
-	struct diff_filespec *one, *two;
-
-	if (options->reverse_diff) {
-		unsigned tmp;
-		const unsigned char *tmp_c;
-		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
-		tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
+	if (read_cache() < 0) {
+		perror("read_cache");
+		return -1;
 	}
-	if (!path) path = "";
-	sprintf(concatpath, "%s%s", base, path);
-	one = alloc_filespec(concatpath);
-	two = alloc_filespec(concatpath);
-	fill_filespec(one, old_sha1, old_mode);
-	fill_filespec(two, new_sha1, new_mode);
-
-	diff_queue(&diff_queued_diff, one, two);
-}
-
-void diff_unmerge(struct diff_options *options,
-		  const char *path)
-{
-	struct diff_filespec *one, *two;
-	one = alloc_filespec(path);
-	two = alloc_filespec(path);
-	diff_queue(&diff_queued_diff, one, two);
+	mark_merge_entries();
+
+	ent = revs->pending_objects->item;
+	tree_name = revs->pending_objects->name;
+	tree = parse_tree_indirect(ent->sha1);
+	if (!tree)
+		return error("bad tree object %s", tree_name);
+	if (read_tree(tree, 1, revs->prune_data))
+		return error("unable to read tree object %s", tree_name);
+	ret = diff_cache(revs, active_cache, active_nr, revs->prune_data,
+			 cached, match_missing);
+	diffcore_std(&revs->diffopt);
+	diff_flush(&revs->diffopt);
+	return ret;
 }
diff --git a/diff.c b/diff.c
new file mode 100644
index 000000000..13b216f27
--- /dev/null
+++ b/diff.c
@@ -0,0 +1,1795 @@
+/*
+ * Copyright (C) 2005 Junio C Hamano
+ */
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include "cache.h"
+#include "quote.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "xdiff-interface.h"
+
+static int use_size_cache;
+
+int diff_rename_limit_default = -1;
+
+int git_diff_config(const char *var, const char *value)
+{
+	if (!strcmp(var, "diff.renamelimit")) {
+		diff_rename_limit_default = git_config_int(var, value);
+		return 0;
+	}
+
+	return git_default_config(var, value);
+}
+
+static char *quote_one(const char *str)
+{
+	int needlen;
+	char *xp;
+
+	if (!str)
+		return NULL;
+	needlen = quote_c_style(str, NULL, NULL, 0);
+	if (!needlen)
+		return strdup(str);
+	xp = xmalloc(needlen + 1);
+	quote_c_style(str, xp, NULL, 0);
+	return xp;
+}
+
+static char *quote_two(const char *one, const char *two)
+{
+	int need_one = quote_c_style(one, NULL, NULL, 1);
+	int need_two = quote_c_style(two, NULL, NULL, 1);
+	char *xp;
+
+	if (need_one + need_two) {
+		if (!need_one) need_one = strlen(one);
+		if (!need_two) need_one = strlen(two);
+
+		xp = xmalloc(need_one + need_two + 3);
+		xp[0] = '"';
+		quote_c_style(one, xp + 1, NULL, 1);
+		quote_c_style(two, xp + need_one + 1, NULL, 1);
+		strcpy(xp + need_one + need_two + 1, "\"");
+		return xp;
+	}
+	need_one = strlen(one);
+	need_two = strlen(two);
+	xp = xmalloc(need_one + need_two + 1);
+	strcpy(xp, one);
+	strcpy(xp + need_one, two);
+	return xp;
+}
+
+static const char *external_diff(void)
+{
+	static const char *external_diff_cmd = NULL;
+	static int done_preparing = 0;
+
+	if (done_preparing)
+		return external_diff_cmd;
+	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
+	done_preparing = 1;
+	return external_diff_cmd;
+}
+
+#define TEMPFILE_PATH_LEN		50
+
+static struct diff_tempfile {
+	const char *name; /* filename external diff should read from */
+	char hex[41];
+	char mode[10];
+	char tmp_path[TEMPFILE_PATH_LEN];
+} diff_temp[2];
+
+static int count_lines(const char *data, int size)
+{
+	int count, ch, completely_empty = 1, nl_just_seen = 0;
+	count = 0;
+	while (0 < size--) {
+		ch = *data++;
+		if (ch == '\n') {
+			count++;
+			nl_just_seen = 1;
+			completely_empty = 0;
+		}
+		else {
+			nl_just_seen = 0;
+			completely_empty = 0;
+		}
+	}
+	if (completely_empty)
+		return 0;
+	if (!nl_just_seen)
+		count++; /* no trailing newline */
+	return count;
+}
+
+static void print_line_count(int count)
+{
+	switch (count) {
+	case 0:
+		printf("0,0");
+		break;
+	case 1:
+		printf("1");
+		break;
+	default:
+		printf("1,%d", count);
+		break;
+	}
+}
+
+static void copy_file(int prefix, const char *data, int size)
+{
+	int ch, nl_just_seen = 1;
+	while (0 < size--) {
+		ch = *data++;
+		if (nl_just_seen)
+			putchar(prefix);
+		putchar(ch);
+		if (ch == '\n')
+			nl_just_seen = 1;
+		else
+			nl_just_seen = 0;
+	}
+	if (!nl_just_seen)
+		printf("\n\\ No newline at end of file\n");
+}
+
+static void emit_rewrite_diff(const char *name_a,
+			      const char *name_b,
+			      struct diff_filespec *one,
+			      struct diff_filespec *two)
+{
+	int lc_a, lc_b;
+	diff_populate_filespec(one, 0);
+	diff_populate_filespec(two, 0);
+	lc_a = count_lines(one->data, one->size);
+	lc_b = count_lines(two->data, two->size);
+	printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
+	print_line_count(lc_a);
+	printf(" +");
+	print_line_count(lc_b);
+	printf(" @@\n");
+	if (lc_a)
+		copy_file('-', one->data, one->size);
+	if (lc_b)
+		copy_file('+', two->data, two->size);
+}
+
+static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
+{
+	if (!DIFF_FILE_VALID(one)) {
+		mf->ptr = ""; /* does not matter */
+		mf->size = 0;
+		return 0;
+	}
+	else if (diff_populate_filespec(one, 0))
+		return -1;
+	mf->ptr = one->data;
+	mf->size = one->size;
+	return 0;
+}
+
+struct emit_callback {
+	const char **label_path;
+};
+
+static int fn_out(void *priv, mmbuffer_t *mb, int nbuf)
+{
+	int i;
+	struct emit_callback *ecbdata = priv;
+
+	if (ecbdata->label_path[0]) {
+		printf("--- %s\n", ecbdata->label_path[0]);
+		printf("+++ %s\n", ecbdata->label_path[1]);
+		ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
+	}
+	for (i = 0; i < nbuf; i++)
+		if (!fwrite(mb[i].ptr, mb[i].size, 1, stdout))
+			return -1;
+	return 0;
+}
+
+static char *pprint_rename(const char *a, const char *b)
+{
+	const char *old = a;
+	const char *new = b;
+	char *name = NULL;
+	int pfx_length, sfx_length;
+	int len_a = strlen(a);
+	int len_b = strlen(b);
+
+	/* Find common prefix */
+	pfx_length = 0;
+	while (*old && *new && *old == *new) {
+		if (*old == '/')
+			pfx_length = old - a + 1;
+		old++;
+		new++;
+	}
+
+	/* Find common suffix */
+	old = a + len_a;
+	new = b + len_b;
+	sfx_length = 0;
+	while (a <= old && b <= new && *old == *new) {
+		if (*old == '/')
+			sfx_length = len_a - (old - a);
+		old--;
+		new--;
+	}
+
+	/*
+	 * pfx{mid-a => mid-b}sfx
+	 * {pfx-a => pfx-b}sfx
+	 * pfx{sfx-a => sfx-b}
+	 * name-a => name-b
+	 */
+	if (pfx_length + sfx_length) {
+		name = xmalloc(len_a + len_b - pfx_length - sfx_length + 7);
+		sprintf(name, "%.*s{%.*s => %.*s}%s",
+			pfx_length, a,
+			len_a - pfx_length - sfx_length, a + pfx_length,
+			len_b - pfx_length - sfx_length, b + pfx_length,
+			a + len_a - sfx_length);
+	}
+	else {
+		name = xmalloc(len_a + len_b + 5);
+		sprintf(name, "%s => %s", a, b);
+	}
+	return name;
+}
+
+struct diffstat_t {
+	struct xdiff_emit_state xm;
+
+	int nr;
+	int alloc;
+	struct diffstat_file {
+		char *name;
+		unsigned is_unmerged:1;
+		unsigned is_binary:1;
+		unsigned is_renamed:1;
+		unsigned int added, deleted;
+	} **files;
+};
+
+static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
+					  const char *name_a,
+					  const char *name_b)
+{
+	struct diffstat_file *x;
+	x = xcalloc(sizeof (*x), 1);
+	if (diffstat->nr == diffstat->alloc) {
+		diffstat->alloc = alloc_nr(diffstat->alloc);
+		diffstat->files = xrealloc(diffstat->files,
+				diffstat->alloc * sizeof(x));
+	}
+	diffstat->files[diffstat->nr++] = x;
+	if (name_b) {
+		x->name = pprint_rename(name_a, name_b);
+		x->is_renamed = 1;
+	}
+	else
+		x->name = strdup(name_a);
+	return x;
+}
+
+static void diffstat_consume(void *priv, char *line, unsigned long len)
+{
+	struct diffstat_t *diffstat = priv;
+	struct diffstat_file *x = diffstat->files[diffstat->nr - 1];
+
+	if (line[0] == '+')
+		x->added++;
+	else if (line[0] == '-')
+		x->deleted++;
+}
+
+static const char pluses[] = "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++";
+static const char minuses[]= "----------------------------------------------------------------------";
+
+static void show_stats(struct diffstat_t* data)
+{
+	char *prefix = "";
+	int i, len, add, del, total, adds = 0, dels = 0;
+	int max, max_change = 0, max_len = 0;
+	int total_files = data->nr;
+
+	if (data->nr == 0)
+		return;
+
+	for (i = 0; i < data->nr; i++) {
+		struct diffstat_file *file = data->files[i];
+
+		len = strlen(file->name);
+		if (max_len < len)
+			max_len = len;
+
+		if (file->is_binary || file->is_unmerged)
+			continue;
+		if (max_change < file->added + file->deleted)
+			max_change = file->added + file->deleted;
+	}
+
+	for (i = 0; i < data->nr; i++) {
+		char *name = data->files[i]->name;
+		int added = data->files[i]->added;
+		int deleted = data->files[i]->deleted;
+
+		if (0 < (len = quote_c_style(name, NULL, NULL, 0))) {
+			char *qname = xmalloc(len + 1);
+			quote_c_style(name, qname, NULL, 0);
+			free(name);
+			data->files[i]->name = name = qname;
+		}
+
+		/*
+		 * "scale" the filename
+		 */
+		len = strlen(name);
+		max = max_len;
+		if (max > 50)
+			max = 50;
+		if (len > max) {
+			char *slash;
+			prefix = "...";
+			max -= 3;
+			name += len - max;
+			slash = strchr(name, '/');
+			if (slash)
+				name = slash;
+		}
+		len = max;
+
+		/*
+		 * scale the add/delete
+		 */
+		max = max_change;
+		if (max + len > 70)
+			max = 70 - len;
+
+		if (data->files[i]->is_binary) {
+			printf(" %s%-*s |  Bin\n", prefix, len, name);
+			goto free_diffstat_file;
+		}
+		else if (data->files[i]->is_unmerged) {
+			printf(" %s%-*s |  Unmerged\n", prefix, len, name);
+			goto free_diffstat_file;
+		}
+		else if (!data->files[i]->is_renamed &&
+			 (added + deleted == 0)) {
+			total_files--;
+			goto free_diffstat_file;
+		}
+
+		add = added;
+		del = deleted;
+		total = add + del;
+		adds += add;
+		dels += del;
+
+		if (max_change > 0) {
+			total = (total * max + max_change / 2) / max_change;
+			add = (add * max + max_change / 2) / max_change;
+			del = total - add;
+		}
+		printf(" %s%-*s |%5d %.*s%.*s\n", prefix,
+				len, name, added + deleted,
+				add, pluses, del, minuses);
+	free_diffstat_file:
+		free(data->files[i]->name);
+		free(data->files[i]);
+	}
+	free(data->files);
+	printf(" %d files changed, %d insertions(+), %d deletions(-)\n",
+			total_files, adds, dels);
+}
+
+#define FIRST_FEW_BYTES 8000
+static int mmfile_is_binary(mmfile_t *mf)
+{
+	long sz = mf->size;
+	if (FIRST_FEW_BYTES < sz)
+		sz = FIRST_FEW_BYTES;
+	if (memchr(mf->ptr, 0, sz))
+		return 1;
+	return 0;
+}
+
+static void builtin_diff(const char *name_a,
+			 const char *name_b,
+			 struct diff_filespec *one,
+			 struct diff_filespec *two,
+			 const char *xfrm_msg,
+			 int complete_rewrite)
+{
+	mmfile_t mf1, mf2;
+	const char *lbl[2];
+	char *a_one, *b_two;
+
+	a_one = quote_two("a/", name_a);
+	b_two = quote_two("b/", name_b);
+	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
+	lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
+	printf("diff --git %s %s\n", a_one, b_two);
+	if (lbl[0][0] == '/') {
+		/* /dev/null */
+		printf("new file mode %06o\n", two->mode);
+		if (xfrm_msg && xfrm_msg[0])
+			puts(xfrm_msg);
+	}
+	else if (lbl[1][0] == '/') {
+		printf("deleted file mode %06o\n", one->mode);
+		if (xfrm_msg && xfrm_msg[0])
+			puts(xfrm_msg);
+	}
+	else {
+		if (one->mode != two->mode) {
+			printf("old mode %06o\n", one->mode);
+			printf("new mode %06o\n", two->mode);
+		}
+		if (xfrm_msg && xfrm_msg[0])
+			puts(xfrm_msg);
+		/*
+		 * we do not run diff between different kind
+		 * of objects.
+		 */
+		if ((one->mode ^ two->mode) & S_IFMT)
+			goto free_ab_and_return;
+		if (complete_rewrite) {
+			emit_rewrite_diff(name_a, name_b, one, two);
+			goto free_ab_and_return;
+		}
+	}
+
+	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
+		die("unable to read files to diff");
+
+	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
+		printf("Binary files %s and %s differ\n", lbl[0], lbl[1]);
+	else {
+		/* Crazy xdl interfaces.. */
+		const char *diffopts = getenv("GIT_DIFF_OPTS");
+		xpparam_t xpp;
+		xdemitconf_t xecfg;
+		xdemitcb_t ecb;
+		struct emit_callback ecbdata;
+
+		ecbdata.label_path = lbl;
+		xpp.flags = XDF_NEED_MINIMAL;
+		xecfg.ctxlen = 3;
+		xecfg.flags = XDL_EMIT_FUNCNAMES;
+		if (!diffopts)
+			;
+		else if (!strncmp(diffopts, "--unified=", 10))
+			xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
+		else if (!strncmp(diffopts, "-u", 2))
+			xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
+		ecb.outf = fn_out;
+		ecb.priv = &ecbdata;
+		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
+	}
+
+ free_ab_and_return:
+	free(a_one);
+	free(b_two);
+	return;
+}
+
+static void builtin_diffstat(const char *name_a, const char *name_b,
+			     struct diff_filespec *one,
+			     struct diff_filespec *two,
+			     struct diffstat_t *diffstat)
+{
+	mmfile_t mf1, mf2;
+	struct diffstat_file *data;
+
+	data = diffstat_add(diffstat, name_a, name_b);
+
+	if (!one || !two) {
+		data->is_unmerged = 1;
+		return;
+	}
+
+	if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
+		die("unable to read files to diff");
+
+	if (mmfile_is_binary(&mf1) || mmfile_is_binary(&mf2))
+		data->is_binary = 1;
+	else {
+		/* Crazy xdl interfaces.. */
+		xpparam_t xpp;
+		xdemitconf_t xecfg;
+		xdemitcb_t ecb;
+
+		xpp.flags = XDF_NEED_MINIMAL;
+		xecfg.ctxlen = 0;
+		xecfg.flags = 0;
+		ecb.outf = xdiff_outf;
+		ecb.priv = diffstat;
+		xdl_diff(&mf1, &mf2, &xpp, &xecfg, &ecb);
+	}
+}
+
+struct diff_filespec *alloc_filespec(const char *path)
+{
+	int namelen = strlen(path);
+	struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
+
+	memset(spec, 0, sizeof(*spec));
+	spec->path = (char *)(spec + 1);
+	memcpy(spec->path, path, namelen+1);
+	return spec;
+}
+
+void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
+		   unsigned short mode)
+{
+	if (mode) {
+		spec->mode = canon_mode(mode);
+		memcpy(spec->sha1, sha1, 20);
+		spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
+	}
+}
+
+/*
+ * Given a name and sha1 pair, if the dircache tells us the file in
+ * the work tree has that object contents, return true, so that
+ * prepare_temp_file() does not have to inflate and extract.
+ */
+static int work_tree_matches(const char *name, const unsigned char *sha1)
+{
+	struct cache_entry *ce;
+	struct stat st;
+	int pos, len;
+
+	/* We do not read the cache ourselves here, because the
+	 * benchmark with my previous version that always reads cache
+	 * shows that it makes things worse for diff-tree comparing
+	 * two linux-2.6 kernel trees in an already checked out work
+	 * tree.  This is because most diff-tree comparisons deal with
+	 * only a small number of files, while reading the cache is
+	 * expensive for a large project, and its cost outweighs the
+	 * savings we get by not inflating the object to a temporary
+	 * file.  Practically, this code only helps when we are used
+	 * by diff-cache --cached, which does read the cache before
+	 * calling us.
+	 */
+	if (!active_cache)
+		return 0;
+
+	len = strlen(name);
+	pos = cache_name_pos(name, len);
+	if (pos < 0)
+		return 0;
+	ce = active_cache[pos];
+	if ((lstat(name, &st) < 0) ||
+	    !S_ISREG(st.st_mode) || /* careful! */
+	    ce_match_stat(ce, &st, 0) ||
+	    memcmp(sha1, ce->sha1, 20))
+		return 0;
+	/* we return 1 only when we can stat, it is a regular file,
+	 * stat information matches, and sha1 recorded in the cache
+	 * matches.  I.e. we know the file in the work tree really is
+	 * the same as the <name, sha1> pair.
+	 */
+	return 1;
+}
+
+static struct sha1_size_cache {
+	unsigned char sha1[20];
+	unsigned long size;
+} **sha1_size_cache;
+static int sha1_size_cache_nr, sha1_size_cache_alloc;
+
+static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
+						 int find_only,
+						 unsigned long size)
+{
+	int first, last;
+	struct sha1_size_cache *e;
+
+	first = 0;
+	last = sha1_size_cache_nr;
+	while (last > first) {
+		int cmp, next = (last + first) >> 1;
+		e = sha1_size_cache[next];
+		cmp = memcmp(e->sha1, sha1, 20);
+		if (!cmp)
+			return e;
+		if (cmp < 0) {
+			last = next;
+			continue;
+		}
+		first = next+1;
+	}
+	/* not found */
+	if (find_only)
+		return NULL;
+	/* insert to make it at "first" */
+	if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
+		sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
+		sha1_size_cache = xrealloc(sha1_size_cache,
+					   sha1_size_cache_alloc *
+					   sizeof(*sha1_size_cache));
+	}
+	sha1_size_cache_nr++;
+	if (first < sha1_size_cache_nr)
+		memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
+			(sha1_size_cache_nr - first - 1) *
+			sizeof(*sha1_size_cache));
+	e = xmalloc(sizeof(struct sha1_size_cache));
+	sha1_size_cache[first] = e;
+	memcpy(e->sha1, sha1, 20);
+	e->size = size;
+	return e;
+}
+
+/*
+ * While doing rename detection and pickaxe operation, we may need to
+ * grab the data for the blob (or file) for our own in-core comparison.
+ * diff_filespec has data and size fields for this purpose.
+ */
+int diff_populate_filespec(struct diff_filespec *s, int size_only)
+{
+	int err = 0;
+	if (!DIFF_FILE_VALID(s))
+		die("internal error: asking to populate invalid file.");
+	if (S_ISDIR(s->mode))
+		return -1;
+
+	if (!use_size_cache)
+		size_only = 0;
+
+	if (s->data)
+		return err;
+	if (!s->sha1_valid ||
+	    work_tree_matches(s->path, s->sha1)) {
+		struct stat st;
+		int fd;
+		if (lstat(s->path, &st) < 0) {
+			if (errno == ENOENT) {
+			err_empty:
+				err = -1;
+			empty:
+				s->data = "";
+				s->size = 0;
+				return err;
+			}
+		}
+		s->size = st.st_size;
+		if (!s->size)
+			goto empty;
+		if (size_only)
+			return 0;
+		if (S_ISLNK(st.st_mode)) {
+			int ret;
+			s->data = xmalloc(s->size);
+			s->should_free = 1;
+			ret = readlink(s->path, s->data, s->size);
+			if (ret < 0) {
+				free(s->data);
+				goto err_empty;
+			}
+			return 0;
+		}
+		fd = open(s->path, O_RDONLY);
+		if (fd < 0)
+			goto err_empty;
+		s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
+		close(fd);
+		if (s->data == MAP_FAILED)
+			goto err_empty;
+		s->should_munmap = 1;
+	}
+	else {
+		char type[20];
+		struct sha1_size_cache *e;
+
+		if (size_only) {
+			e = locate_size_cache(s->sha1, 1, 0);
+			if (e) {
+				s->size = e->size;
+				return 0;
+			}
+			if (!sha1_object_info(s->sha1, type, &s->size))
+				locate_size_cache(s->sha1, 0, s->size);
+		}
+		else {
+			s->data = read_sha1_file(s->sha1, type, &s->size);
+			s->should_free = 1;
+		}
+	}
+	return 0;
+}
+
+void diff_free_filespec_data(struct diff_filespec *s)
+{
+	if (s->should_free)
+		free(s->data);
+	else if (s->should_munmap)
+		munmap(s->data, s->size);
+	s->should_free = s->should_munmap = 0;
+	s->data = NULL;
+	free(s->cnt_data);
+	s->cnt_data = NULL;
+}
+
+static void prep_temp_blob(struct diff_tempfile *temp,
+			   void *blob,
+			   unsigned long size,
+			   const unsigned char *sha1,
+			   int mode)
+{
+	int fd;
+
+	fd = git_mkstemp(temp->tmp_path, TEMPFILE_PATH_LEN, ".diff_XXXXXX");
+	if (fd < 0)
+		die("unable to create temp-file");
+	if (write(fd, blob, size) != size)
+		die("unable to write temp-file");
+	close(fd);
+	temp->name = temp->tmp_path;
+	strcpy(temp->hex, sha1_to_hex(sha1));
+	temp->hex[40] = 0;
+	sprintf(temp->mode, "%06o", mode);
+}
+
+static void prepare_temp_file(const char *name,
+			      struct diff_tempfile *temp,
+			      struct diff_filespec *one)
+{
+	if (!DIFF_FILE_VALID(one)) {
+	not_a_valid_file:
+		/* A '-' entry produces this for file-2, and
+		 * a '+' entry produces this for file-1.
+		 */
+		temp->name = "/dev/null";
+		strcpy(temp->hex, ".");
+		strcpy(temp->mode, ".");
+		return;
+	}
+
+	if (!one->sha1_valid ||
+	    work_tree_matches(name, one->sha1)) {
+		struct stat st;
+		if (lstat(name, &st) < 0) {
+			if (errno == ENOENT)
+				goto not_a_valid_file;
+			die("stat(%s): %s", name, strerror(errno));
+		}
+		if (S_ISLNK(st.st_mode)) {
+			int ret;
+			char buf[PATH_MAX + 1]; /* ought to be SYMLINK_MAX */
+			if (sizeof(buf) <= st.st_size)
+				die("symlink too long: %s", name);
+			ret = readlink(name, buf, st.st_size);
+			if (ret < 0)
+				die("readlink(%s)", name);
+			prep_temp_blob(temp, buf, st.st_size,
+				       (one->sha1_valid ?
+					one->sha1 : null_sha1),
+				       (one->sha1_valid ?
+					one->mode : S_IFLNK));
+		}
+		else {
+			/* we can borrow from the file in the work tree */
+			temp->name = name;
+			if (!one->sha1_valid)
+				strcpy(temp->hex, sha1_to_hex(null_sha1));
+			else
+				strcpy(temp->hex, sha1_to_hex(one->sha1));
+			/* Even though we may sometimes borrow the
+			 * contents from the work tree, we always want
+			 * one->mode.  mode is trustworthy even when
+			 * !(one->sha1_valid), as long as
+			 * DIFF_FILE_VALID(one).
+			 */
+			sprintf(temp->mode, "%06o", one->mode);
+		}
+		return;
+	}
+	else {
+		if (diff_populate_filespec(one, 0))
+			die("cannot read data blob for %s", one->path);
+		prep_temp_blob(temp, one->data, one->size,
+			       one->sha1, one->mode);
+	}
+}
+
+static void remove_tempfile(void)
+{
+	int i;
+
+	for (i = 0; i < 2; i++)
+		if (diff_temp[i].name == diff_temp[i].tmp_path) {
+			unlink(diff_temp[i].name);
+			diff_temp[i].name = NULL;
+		}
+}
+
+static void remove_tempfile_on_signal(int signo)
+{
+	remove_tempfile();
+	signal(SIGINT, SIG_DFL);
+	raise(signo);
+}
+
+static int spawn_prog(const char *pgm, const char **arg)
+{
+	pid_t pid;
+	int status;
+
+	fflush(NULL);
+	pid = fork();
+	if (pid < 0)
+		die("unable to fork");
+	if (!pid) {
+		execvp(pgm, (char *const*) arg);
+		exit(255);
+	}
+
+	while (waitpid(pid, &status, 0) < 0) {
+		if (errno == EINTR)
+			continue;
+		return -1;
+	}
+
+	/* Earlier we did not check the exit status because
+	 * diff exits non-zero if files are different, and
+	 * we are not interested in knowing that.  It was a
+	 * mistake which made it harder to quit a diff-*
+	 * session that uses the git-apply-patch-script as
+	 * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
+	 * should also exit non-zero only when it wants to
+	 * abort the entire diff-* session.
+	 */
+	if (WIFEXITED(status) && !WEXITSTATUS(status))
+		return 0;
+	return -1;
+}
+
+/* An external diff command takes:
+ *
+ * diff-cmd name infile1 infile1-sha1 infile1-mode \
+ *               infile2 infile2-sha1 infile2-mode [ rename-to ]
+ *
+ */
+static void run_external_diff(const char *pgm,
+			      const char *name,
+			      const char *other,
+			      struct diff_filespec *one,
+			      struct diff_filespec *two,
+			      const char *xfrm_msg,
+			      int complete_rewrite)
+{
+	const char *spawn_arg[10];
+	struct diff_tempfile *temp = diff_temp;
+	int retval;
+	static int atexit_asked = 0;
+	const char *othername;
+	const char **arg = &spawn_arg[0];
+
+	othername = (other? other : name);
+	if (one && two) {
+		prepare_temp_file(name, &temp[0], one);
+		prepare_temp_file(othername, &temp[1], two);
+		if (! atexit_asked &&
+		    (temp[0].name == temp[0].tmp_path ||
+		     temp[1].name == temp[1].tmp_path)) {
+			atexit_asked = 1;
+			atexit(remove_tempfile);
+		}
+		signal(SIGINT, remove_tempfile_on_signal);
+	}
+
+	if (one && two) {
+		*arg++ = pgm;
+		*arg++ = name;
+		*arg++ = temp[0].name;
+		*arg++ = temp[0].hex;
+		*arg++ = temp[0].mode;
+		*arg++ = temp[1].name;
+		*arg++ = temp[1].hex;
+		*arg++ = temp[1].mode;
+		if (other) {
+			*arg++ = other;
+			*arg++ = xfrm_msg;
+		}
+	} else {
+		*arg++ = pgm;
+		*arg++ = name;
+	}
+	*arg = NULL;
+	retval = spawn_prog(pgm, spawn_arg);
+	remove_tempfile();
+	if (retval) {
+		fprintf(stderr, "external diff died, stopping at %s.\n", name);
+		exit(1);
+	}
+}
+
+static void run_diff_cmd(const char *pgm,
+			 const char *name,
+			 const char *other,
+			 struct diff_filespec *one,
+			 struct diff_filespec *two,
+			 const char *xfrm_msg,
+			 int complete_rewrite)
+{
+	if (pgm) {
+		run_external_diff(pgm, name, other, one, two, xfrm_msg,
+				  complete_rewrite);
+		return;
+	}
+	if (one && two)
+		builtin_diff(name, other ? other : name,
+			     one, two, xfrm_msg, complete_rewrite);
+	else
+		printf("* Unmerged path %s\n", name);
+}
+
+static void diff_fill_sha1_info(struct diff_filespec *one)
+{
+	if (DIFF_FILE_VALID(one)) {
+		if (!one->sha1_valid) {
+			struct stat st;
+			if (lstat(one->path, &st) < 0)
+				die("stat %s", one->path);
+			if (index_path(one->sha1, one->path, &st, 0))
+				die("cannot hash %s\n", one->path);
+		}
+	}
+	else
+		memset(one->sha1, 0, 20);
+}
+
+static void run_diff(struct diff_filepair *p, struct diff_options *o)
+{
+	const char *pgm = external_diff();
+	char msg[PATH_MAX*2+300], *xfrm_msg;
+	struct diff_filespec *one;
+	struct diff_filespec *two;
+	const char *name;
+	const char *other;
+	char *name_munged, *other_munged;
+	int complete_rewrite = 0;
+	int len;
+
+	if (DIFF_PAIR_UNMERGED(p)) {
+		/* unmerged */
+		run_diff_cmd(pgm, p->one->path, NULL, NULL, NULL, NULL, 0);
+		return;
+	}
+
+	name = p->one->path;
+	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
+	name_munged = quote_one(name);
+	other_munged = quote_one(other);
+	one = p->one; two = p->two;
+
+	diff_fill_sha1_info(one);
+	diff_fill_sha1_info(two);
+
+	len = 0;
+	switch (p->status) {
+	case DIFF_STATUS_COPIED:
+		len += snprintf(msg + len, sizeof(msg) - len,
+				"similarity index %d%%\n"
+				"copy from %s\n"
+				"copy to %s\n",
+				(int)(0.5 + p->score * 100.0/MAX_SCORE),
+				name_munged, other_munged);
+		break;
+	case DIFF_STATUS_RENAMED:
+		len += snprintf(msg + len, sizeof(msg) - len,
+				"similarity index %d%%\n"
+				"rename from %s\n"
+				"rename to %s\n",
+				(int)(0.5 + p->score * 100.0/MAX_SCORE),
+				name_munged, other_munged);
+		break;
+	case DIFF_STATUS_MODIFIED:
+		if (p->score) {
+			len += snprintf(msg + len, sizeof(msg) - len,
+					"dissimilarity index %d%%\n",
+					(int)(0.5 + p->score *
+					      100.0/MAX_SCORE));
+			complete_rewrite = 1;
+			break;
+		}
+		/* fallthru */
+	default:
+		/* nothing */
+		;
+	}
+
+	if (memcmp(one->sha1, two->sha1, 20)) {
+		char one_sha1[41];
+		int abbrev = o->full_index ? 40 : DEFAULT_ABBREV;
+		memcpy(one_sha1, sha1_to_hex(one->sha1), 41);
+
+		len += snprintf(msg + len, sizeof(msg) - len,
+				"index %.*s..%.*s",
+				abbrev, one_sha1, abbrev,
+				sha1_to_hex(two->sha1));
+		if (one->mode == two->mode)
+			len += snprintf(msg + len, sizeof(msg) - len,
+					" %06o", one->mode);
+		len += snprintf(msg + len, sizeof(msg) - len, "\n");
+	}
+
+	if (len)
+		msg[--len] = 0;
+	xfrm_msg = len ? msg : NULL;
+
+	if (!pgm &&
+	    DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
+	    (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
+		/* a filepair that changes between file and symlink
+		 * needs to be split into deletion and creation.
+		 */
+		struct diff_filespec *null = alloc_filespec(two->path);
+		run_diff_cmd(NULL, name, other, one, null, xfrm_msg, 0);
+		free(null);
+		null = alloc_filespec(one->path);
+		run_diff_cmd(NULL, name, other, null, two, xfrm_msg, 0);
+		free(null);
+	}
+	else
+		run_diff_cmd(pgm, name, other, one, two, xfrm_msg,
+			     complete_rewrite);
+
+	free(name_munged);
+	free(other_munged);
+}
+
+static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
+			 struct diffstat_t *diffstat)
+{
+	const char *name;
+	const char *other;
+
+	if (DIFF_PAIR_UNMERGED(p)) {
+		/* unmerged */
+		builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat);
+		return;
+	}
+
+	name = p->one->path;
+	other = (strcmp(name, p->two->path) ? p->two->path : NULL);
+
+	diff_fill_sha1_info(p->one);
+	diff_fill_sha1_info(p->two);
+
+	builtin_diffstat(name, other, p->one, p->two, diffstat);
+}
+
+void diff_setup(struct diff_options *options)
+{
+	memset(options, 0, sizeof(*options));
+	options->output_format = DIFF_FORMAT_RAW;
+	options->line_termination = '\n';
+	options->break_opt = -1;
+	options->rename_limit = -1;
+
+	options->change = diff_change;
+	options->add_remove = diff_addremove;
+}
+
+int diff_setup_done(struct diff_options *options)
+{
+	if ((options->find_copies_harder &&
+	     options->detect_rename != DIFF_DETECT_COPY) ||
+	    (0 <= options->rename_limit && !options->detect_rename))
+		return -1;
+
+	/*
+	 * These cases always need recursive; we do not drop caller-supplied
+	 * recursive bits for other formats here.
+	 */
+	if ((options->output_format == DIFF_FORMAT_PATCH) ||
+	    (options->output_format == DIFF_FORMAT_DIFFSTAT))
+		options->recursive = 1;
+
+	if (options->detect_rename && options->rename_limit < 0)
+		options->rename_limit = diff_rename_limit_default;
+	if (options->setup & DIFF_SETUP_USE_CACHE) {
+		if (!active_cache)
+			/* read-cache does not die even when it fails
+			 * so it is safe for us to do this here.  Also
+			 * it does not smudge active_cache or active_nr
+			 * when it fails, so we do not have to worry about
+			 * cleaning it up ourselves either.
+			 */
+			read_cache();
+	}
+	if (options->setup & DIFF_SETUP_USE_SIZE_CACHE)
+		use_size_cache = 1;
+	if (options->abbrev <= 0 || 40 < options->abbrev)
+		options->abbrev = 40; /* full */
+
+	return 0;
+}
+
+int diff_opt_parse(struct diff_options *options, const char **av, int ac)
+{
+	const char *arg = av[0];
+	if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
+		options->output_format = DIFF_FORMAT_PATCH;
+	else if (!strcmp(arg, "--patch-with-raw")) {
+		options->output_format = DIFF_FORMAT_PATCH;
+		options->with_raw = 1;
+	}
+	else if (!strcmp(arg, "--stat"))
+		options->output_format = DIFF_FORMAT_DIFFSTAT;
+	else if (!strcmp(arg, "--patch-with-stat")) {
+		options->output_format = DIFF_FORMAT_PATCH;
+		options->with_stat = 1;
+	}
+	else if (!strcmp(arg, "-z"))
+		options->line_termination = 0;
+	else if (!strncmp(arg, "-l", 2))
+		options->rename_limit = strtoul(arg+2, NULL, 10);
+	else if (!strcmp(arg, "--full-index"))
+		options->full_index = 1;
+	else if (!strcmp(arg, "--name-only"))
+		options->output_format = DIFF_FORMAT_NAME;
+	else if (!strcmp(arg, "--name-status"))
+		options->output_format = DIFF_FORMAT_NAME_STATUS;
+	else if (!strcmp(arg, "-R"))
+		options->reverse_diff = 1;
+	else if (!strncmp(arg, "-S", 2))
+		options->pickaxe = arg + 2;
+	else if (!strcmp(arg, "-s"))
+		options->output_format = DIFF_FORMAT_NO_OUTPUT;
+	else if (!strncmp(arg, "-O", 2))
+		options->orderfile = arg + 2;
+	else if (!strncmp(arg, "--diff-filter=", 14))
+		options->filter = arg + 14;
+	else if (!strcmp(arg, "--pickaxe-all"))
+		options->pickaxe_opts = DIFF_PICKAXE_ALL;
+	else if (!strcmp(arg, "--pickaxe-regex"))
+		options->pickaxe_opts = DIFF_PICKAXE_REGEX;
+	else if (!strncmp(arg, "-B", 2)) {
+		if ((options->break_opt =
+		     diff_scoreopt_parse(arg)) == -1)
+			return -1;
+	}
+	else if (!strncmp(arg, "-M", 2)) {
+		if ((options->rename_score =
+		     diff_scoreopt_parse(arg)) == -1)
+			return -1;
+		options->detect_rename = DIFF_DETECT_RENAME;
+	}
+	else if (!strncmp(arg, "-C", 2)) {
+		if ((options->rename_score =
+		     diff_scoreopt_parse(arg)) == -1)
+			return -1;
+		options->detect_rename = DIFF_DETECT_COPY;
+	}
+	else if (!strcmp(arg, "--find-copies-harder"))
+		options->find_copies_harder = 1;
+	else if (!strcmp(arg, "--abbrev"))
+		options->abbrev = DEFAULT_ABBREV;
+	else if (!strncmp(arg, "--abbrev=", 9)) {
+		options->abbrev = strtoul(arg + 9, NULL, 10);
+		if (options->abbrev < MINIMUM_ABBREV)
+			options->abbrev = MINIMUM_ABBREV;
+		else if (40 < options->abbrev)
+			options->abbrev = 40;
+	}
+	else
+		return 0;
+	return 1;
+}
+
+static int parse_num(const char **cp_p)
+{
+	unsigned long num, scale;
+	int ch, dot;
+	const char *cp = *cp_p;
+
+	num = 0;
+	scale = 1;
+	dot = 0;
+	for(;;) {
+		ch = *cp;
+		if ( !dot && ch == '.' ) {
+			scale = 1;
+			dot = 1;
+		} else if ( ch == '%' ) {
+			scale = dot ? scale*100 : 100;
+			cp++;	/* % is always at the end */
+			break;
+		} else if ( ch >= '0' && ch <= '9' ) {
+			if ( scale < 100000 ) {
+				scale *= 10;
+				num = (num*10) + (ch-'0');
+			}
+		} else {
+			break;
+		}
+		cp++;
+	}
+	*cp_p = cp;
+
+	/* user says num divided by scale and we say internally that
+	 * is MAX_SCORE * num / scale.
+	 */
+	return (num >= scale) ? MAX_SCORE : (MAX_SCORE * num / scale);
+}
+
+int diff_scoreopt_parse(const char *opt)
+{
+	int opt1, opt2, cmd;
+
+	if (*opt++ != '-')
+		return -1;
+	cmd = *opt++;
+	if (cmd != 'M' && cmd != 'C' && cmd != 'B')
+		return -1; /* that is not a -M, -C nor -B option */
+
+	opt1 = parse_num(&opt);
+	if (cmd != 'B')
+		opt2 = 0;
+	else {
+		if (*opt == 0)
+			opt2 = 0;
+		else if (*opt != '/')
+			return -1; /* we expect -B80/99 or -B80 */
+		else {
+			opt++;
+			opt2 = parse_num(&opt);
+		}
+	}
+	if (*opt != 0)
+		return -1;
+	return opt1 | (opt2 << 16);
+}
+
+struct diff_queue_struct diff_queued_diff;
+
+void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
+{
+	if (queue->alloc <= queue->nr) {
+		queue->alloc = alloc_nr(queue->alloc);
+		queue->queue = xrealloc(queue->queue,
+					sizeof(dp) * queue->alloc);
+	}
+	queue->queue[queue->nr++] = dp;
+}
+
+struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
+				 struct diff_filespec *one,
+				 struct diff_filespec *two)
+{
+	struct diff_filepair *dp = xmalloc(sizeof(*dp));
+	dp->one = one;
+	dp->two = two;
+	dp->score = 0;
+	dp->status = 0;
+	dp->source_stays = 0;
+	dp->broken_pair = 0;
+	if (queue)
+		diff_q(queue, dp);
+	return dp;
+}
+
+void diff_free_filepair(struct diff_filepair *p)
+{
+	diff_free_filespec_data(p->one);
+	diff_free_filespec_data(p->two);
+	free(p->one);
+	free(p->two);
+	free(p);
+}
+
+/* This is different from find_unique_abbrev() in that
+ * it stuffs the result with dots for alignment.
+ */
+const char *diff_unique_abbrev(const unsigned char *sha1, int len)
+{
+	int abblen;
+	const char *abbrev;
+	if (len == 40)
+		return sha1_to_hex(sha1);
+
+	abbrev = find_unique_abbrev(sha1, len);
+	if (!abbrev)
+		return sha1_to_hex(sha1);
+	abblen = strlen(abbrev);
+	if (abblen < 37) {
+		static char hex[41];
+		if (len < abblen && abblen <= len + 2)
+			sprintf(hex, "%s%.*s", abbrev, len+3-abblen, "..");
+		else
+			sprintf(hex, "%s...", abbrev);
+		return hex;
+	}
+	return sha1_to_hex(sha1);
+}
+
+static void diff_flush_raw(struct diff_filepair *p,
+			   int line_termination,
+			   int inter_name_termination,
+			   struct diff_options *options,
+			   int output_format)
+{
+	int two_paths;
+	char status[10];
+	int abbrev = options->abbrev;
+	const char *path_one, *path_two;
+
+	path_one = p->one->path;
+	path_two = p->two->path;
+	if (line_termination) {
+		path_one = quote_one(path_one);
+		path_two = quote_one(path_two);
+	}
+
+	if (p->score)
+		sprintf(status, "%c%03d", p->status,
+			(int)(0.5 + p->score * 100.0/MAX_SCORE));
+	else {
+		status[0] = p->status;
+		status[1] = 0;
+	}
+	switch (p->status) {
+	case DIFF_STATUS_COPIED:
+	case DIFF_STATUS_RENAMED:
+		two_paths = 1;
+		break;
+	case DIFF_STATUS_ADDED:
+	case DIFF_STATUS_DELETED:
+		two_paths = 0;
+		break;
+	default:
+		two_paths = 0;
+		break;
+	}
+	if (output_format != DIFF_FORMAT_NAME_STATUS) {
+		printf(":%06o %06o %s ",
+		       p->one->mode, p->two->mode,
+		       diff_unique_abbrev(p->one->sha1, abbrev));
+		printf("%s ",
+		       diff_unique_abbrev(p->two->sha1, abbrev));
+	}
+	printf("%s%c%s", status, inter_name_termination, path_one);
+	if (two_paths)
+		printf("%c%s", inter_name_termination, path_two);
+	putchar(line_termination);
+	if (path_one != p->one->path)
+		free((void*)path_one);
+	if (path_two != p->two->path)
+		free((void*)path_two);
+}
+
+static void diff_flush_name(struct diff_filepair *p,
+			    int inter_name_termination,
+			    int line_termination)
+{
+	char *path = p->two->path;
+
+	if (line_termination)
+		path = quote_one(p->two->path);
+	else
+		path = p->two->path;
+	printf("%s%c", path, line_termination);
+	if (p->two->path != path)
+		free(path);
+}
+
+int diff_unmodified_pair(struct diff_filepair *p)
+{
+	/* This function is written stricter than necessary to support
+	 * the currently implemented transformers, but the idea is to
+	 * let transformers to produce diff_filepairs any way they want,
+	 * and filter and clean them up here before producing the output.
+	 */
+	struct diff_filespec *one, *two;
+
+	if (DIFF_PAIR_UNMERGED(p))
+		return 0; /* unmerged is interesting */
+
+	one = p->one;
+	two = p->two;
+
+	/* deletion, addition, mode or type change
+	 * and rename are all interesting.
+	 */
+	if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
+	    DIFF_PAIR_MODE_CHANGED(p) ||
+	    strcmp(one->path, two->path))
+		return 0;
+
+	/* both are valid and point at the same path.  that is, we are
+	 * dealing with a change.
+	 */
+	if (one->sha1_valid && two->sha1_valid &&
+	    !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
+		return 1; /* no change */
+	if (!one->sha1_valid && !two->sha1_valid)
+		return 1; /* both look at the same file on the filesystem. */
+	return 0;
+}
+
+static void diff_flush_patch(struct diff_filepair *p, struct diff_options *o)
+{
+	if (diff_unmodified_pair(p))
+		return;
+
+	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
+	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
+		return; /* no tree diffs in patch format */
+
+	run_diff(p, o);
+}
+
+static void diff_flush_stat(struct diff_filepair *p, struct diff_options *o,
+			    struct diffstat_t *diffstat)
+{
+	if (diff_unmodified_pair(p))
+		return;
+
+	if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
+	    (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
+		return; /* no tree diffs in patch format */
+
+	run_diffstat(p, o, diffstat);
+}
+
+int diff_queue_is_empty(void)
+{
+	struct diff_queue_struct *q = &diff_queued_diff;
+	int i;
+	for (i = 0; i < q->nr; i++)
+		if (!diff_unmodified_pair(q->queue[i]))
+			return 0;
+	return 1;
+}
+
+#if DIFF_DEBUG
+void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
+{
+	fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
+		x, one ? one : "",
+		s->path,
+		DIFF_FILE_VALID(s) ? "valid" : "invalid",
+		s->mode,
+		s->sha1_valid ? sha1_to_hex(s->sha1) : "");
+	fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
+		x, one ? one : "",
+		s->size, s->xfrm_flags);
+}
+
+void diff_debug_filepair(const struct diff_filepair *p, int i)
+{
+	diff_debug_filespec(p->one, i, "one");
+	diff_debug_filespec(p->two, i, "two");
+	fprintf(stderr, "score %d, status %c stays %d broken %d\n",
+		p->score, p->status ? p->status : '?',
+		p->source_stays, p->broken_pair);
+}
+
+void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
+{
+	int i;
+	if (msg)
+		fprintf(stderr, "%s\n", msg);
+	fprintf(stderr, "q->nr = %d\n", q->nr);
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filepair *p = q->queue[i];
+		diff_debug_filepair(p, i);
+	}
+}
+#endif
+
+static void diff_resolve_rename_copy(void)
+{
+	int i, j;
+	struct diff_filepair *p, *pp;
+	struct diff_queue_struct *q = &diff_queued_diff;
+
+	diff_debug_queue("resolve-rename-copy", q);
+
+	for (i = 0; i < q->nr; i++) {
+		p = q->queue[i];
+		p->status = 0; /* undecided */
+		if (DIFF_PAIR_UNMERGED(p))
+			p->status = DIFF_STATUS_UNMERGED;
+		else if (!DIFF_FILE_VALID(p->one))
+			p->status = DIFF_STATUS_ADDED;
+		else if (!DIFF_FILE_VALID(p->two))
+			p->status = DIFF_STATUS_DELETED;
+		else if (DIFF_PAIR_TYPE_CHANGED(p))
+			p->status = DIFF_STATUS_TYPE_CHANGED;
+
+		/* from this point on, we are dealing with a pair
+		 * whose both sides are valid and of the same type, i.e.
+		 * either in-place edit or rename/copy edit.
+		 */
+		else if (DIFF_PAIR_RENAME(p)) {
+			if (p->source_stays) {
+				p->status = DIFF_STATUS_COPIED;
+				continue;
+			}
+			/* See if there is some other filepair that
+			 * copies from the same source as us.  If so
+			 * we are a copy.  Otherwise we are either a
+			 * copy if the path stays, or a rename if it
+			 * does not, but we already handled "stays" case.
+			 */
+			for (j = i + 1; j < q->nr; j++) {
+				pp = q->queue[j];
+				if (strcmp(pp->one->path, p->one->path))
+					continue; /* not us */
+				if (!DIFF_PAIR_RENAME(pp))
+					continue; /* not a rename/copy */
+				/* pp is a rename/copy from the same source */
+				p->status = DIFF_STATUS_COPIED;
+				break;
+			}
+			if (!p->status)
+				p->status = DIFF_STATUS_RENAMED;
+		}
+		else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
+			 p->one->mode != p->two->mode)
+			p->status = DIFF_STATUS_MODIFIED;
+		else {
+			/* This is a "no-change" entry and should not
+			 * happen anymore, but prepare for broken callers.
+			 */
+			error("feeding unmodified %s to diffcore",
+			      p->one->path);
+			p->status = DIFF_STATUS_UNKNOWN;
+		}
+	}
+	diff_debug_queue("resolve-rename-copy done", q);
+}
+
+static void flush_one_pair(struct diff_filepair *p,
+			   int diff_output_format,
+			   struct diff_options *options,
+			   struct diffstat_t *diffstat)
+{
+	int inter_name_termination = '\t';
+	int line_termination = options->line_termination;
+	if (!line_termination)
+		inter_name_termination = 0;
+
+	switch (p->status) {
+	case DIFF_STATUS_UNKNOWN:
+		break;
+	case 0:
+		die("internal error in diff-resolve-rename-copy");
+		break;
+	default:
+		switch (diff_output_format) {
+		case DIFF_FORMAT_DIFFSTAT:
+			diff_flush_stat(p, options, diffstat);
+			break;
+		case DIFF_FORMAT_PATCH:
+			diff_flush_patch(p, options);
+			break;
+		case DIFF_FORMAT_RAW:
+		case DIFF_FORMAT_NAME_STATUS:
+			diff_flush_raw(p, line_termination,
+				       inter_name_termination,
+				       options, diff_output_format);
+			break;
+		case DIFF_FORMAT_NAME:
+			diff_flush_name(p,
+					inter_name_termination,
+					line_termination);
+			break;
+		case DIFF_FORMAT_NO_OUTPUT:
+			break;
+		}
+	}
+}
+
+void diff_flush(struct diff_options *options)
+{
+	struct diff_queue_struct *q = &diff_queued_diff;
+	int i;
+	int diff_output_format = options->output_format;
+	struct diffstat_t *diffstat = NULL;
+
+	if (diff_output_format == DIFF_FORMAT_DIFFSTAT || options->with_stat) {
+		diffstat = xcalloc(sizeof (struct diffstat_t), 1);
+		diffstat->xm.consume = diffstat_consume;
+	}
+
+	if (options->with_raw) {
+		for (i = 0; i < q->nr; i++) {
+			struct diff_filepair *p = q->queue[i];
+			flush_one_pair(p, DIFF_FORMAT_RAW, options, NULL);
+		}
+		putchar(options->line_termination);
+	}
+	if (options->with_stat) {
+		for (i = 0; i < q->nr; i++) {
+			struct diff_filepair *p = q->queue[i];
+			flush_one_pair(p, DIFF_FORMAT_DIFFSTAT, options,
+				       diffstat);
+		}
+		show_stats(diffstat);
+		free(diffstat);
+		diffstat = NULL;
+		putchar(options->line_termination);
+	}
+	for (i = 0; i < q->nr; i++) {
+		struct diff_filepair *p = q->queue[i];
+		flush_one_pair(p, diff_output_format, options, diffstat);
+		diff_free_filepair(p);
+	}
+
+	if (diffstat) {
+		show_stats(diffstat);
+		free(diffstat);
+	}
+
+	free(q->queue);
+	q->queue = NULL;
+	q->nr = q->alloc = 0;
+}
+
+static void diffcore_apply_filter(const char *filter)
+{
+	int i;
+	struct diff_queue_struct *q = &diff_queued_diff;
+	struct diff_queue_struct outq;
+	outq.queue = NULL;
+	outq.nr = outq.alloc = 0;
+
+	if (!filter)
+		return;
+
+	if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
+		int found;
+		for (i = found = 0; !found && i < q->nr; i++) {
+			struct diff_filepair *p = q->queue[i];
+			if (((p->status == DIFF_STATUS_MODIFIED) &&
+			     ((p->score &&
+			       strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
+			      (!p->score &&
+			       strchr(filter, DIFF_STATUS_MODIFIED)))) ||
+			    ((p->status != DIFF_STATUS_MODIFIED) &&
+			     strchr(filter, p->status)))
+				found++;
+		}
+		if (found)
+			return;
+
+		/* otherwise we will clear the whole queue
+		 * by copying the empty outq at the end of this
+		 * function, but first clear the current entries
+		 * in the queue.
+		 */
+		for (i = 0; i < q->nr; i++)
+			diff_free_filepair(q->queue[i]);
+	}
+	else {
+		/* Only the matching ones */
+		for (i = 0; i < q->nr; i++) {
+			struct diff_filepair *p = q->queue[i];
+
+			if (((p->status == DIFF_STATUS_MODIFIED) &&
+			     ((p->score &&
+			       strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
+			      (!p->score &&
+			       strchr(filter, DIFF_STATUS_MODIFIED)))) ||
+			    ((p->status != DIFF_STATUS_MODIFIED) &&
+			     strchr(filter, p->status)))
+				diff_q(&outq, p);
+			else
+				diff_free_filepair(p);
+		}
+	}
+	free(q->queue);
+	*q = outq;
+}
+
+void diffcore_std(struct diff_options *options)
+{
+	if (options->break_opt != -1)
+		diffcore_break(options->break_opt);
+	if (options->detect_rename)
+		diffcore_rename(options);
+	if (options->break_opt != -1)
+		diffcore_merge_broken();
+	if (options->pickaxe)
+		diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
+	if (options->orderfile)
+		diffcore_order(options->orderfile);
+	diff_resolve_rename_copy();
+	diffcore_apply_filter(options->filter);
+}
+
+
+void diffcore_std_no_resolve(struct diff_options *options)
+{
+	if (options->pickaxe)
+		diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
+	if (options->orderfile)
+		diffcore_order(options->orderfile);
+	diffcore_apply_filter(options->filter);
+}
+
+void diff_addremove(struct diff_options *options,
+		    int addremove, unsigned mode,
+		    const unsigned char *sha1,
+		    const char *base, const char *path)
+{
+	char concatpath[PATH_MAX];
+	struct diff_filespec *one, *two;
+
+	/* This may look odd, but it is a preparation for
+	 * feeding "there are unchanged files which should
+	 * not produce diffs, but when you are doing copy
+	 * detection you would need them, so here they are"
+	 * entries to the diff-core.  They will be prefixed
+	 * with something like '=' or '*' (I haven't decided
+	 * which but should not make any difference).
+	 * Feeding the same new and old to diff_change() 
+	 * also has the same effect.
+	 * Before the final output happens, they are pruned after
+	 * merged into rename/copy pairs as appropriate.
+	 */
+	if (options->reverse_diff)
+		addremove = (addremove == '+' ? '-' :
+			     addremove == '-' ? '+' : addremove);
+
+	if (!path) path = "";
+	sprintf(concatpath, "%s%s", base, path);
+	one = alloc_filespec(concatpath);
+	two = alloc_filespec(concatpath);
+
+	if (addremove != '+')
+		fill_filespec(one, sha1, mode);
+	if (addremove != '-')
+		fill_filespec(two, sha1, mode);
+
+	diff_queue(&diff_queued_diff, one, two);
+}
+
+void diff_change(struct diff_options *options,
+		 unsigned old_mode, unsigned new_mode,
+		 const unsigned char *old_sha1,
+		 const unsigned char *new_sha1,
+		 const char *base, const char *path) 
+{
+	char concatpath[PATH_MAX];
+	struct diff_filespec *one, *two;
+
+	if (options->reverse_diff) {
+		unsigned tmp;
+		const unsigned char *tmp_c;
+		tmp = old_mode; old_mode = new_mode; new_mode = tmp;
+		tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
+	}
+	if (!path) path = "";
+	sprintf(concatpath, "%s%s", base, path);
+	one = alloc_filespec(concatpath);
+	two = alloc_filespec(concatpath);
+	fill_filespec(one, old_sha1, old_mode);
+	fill_filespec(two, new_sha1, new_mode);
+
+	diff_queue(&diff_queued_diff, one, two);
+}
+
+void diff_unmerge(struct diff_options *options,
+		  const char *path)
+{
+	struct diff_filespec *one, *two;
+	one = alloc_filespec(path);
+	two = alloc_filespec(path);
+	diff_queue(&diff_queued_diff, one, two);
+}
diff --git a/diff.h b/diff.h
index 52fff6643..7150b9038 100644
--- a/diff.h
+++ b/diff.h
@@ -28,10 +28,11 @@ struct diff_options {
 		 with_raw:1,
 		 with_stat:1,
 		 tree_in_recursive:1,
-		 full_index:1;
+		 full_index:1,
+		 silent_on_remove:1,
+		 find_copies_harder:1;
 	int break_opt;
 	int detect_rename;
-	int find_copies_harder;
 	int line_termination;
 	int output_format;
 	int pickaxe_opts;
@@ -168,4 +169,8 @@ extern void diff_flush(struct diff_options*);
 
 extern const char *diff_unique_abbrev(const unsigned char *, int);
 
+extern int run_diff_files(struct rev_info *revs, int silent_on_removed);
+
+extern int run_diff_index(struct rev_info *revs, int cached);
+
 #endif /* DIFF_H */
diff --git a/gitk b/gitk
index 87e71629a..5362b76be 100755
--- a/gitk
+++ b/gitk
@@ -16,22 +16,6 @@ proc gitdir {} {
     }
 }
 
-proc parse_args {rargs} {
-    global parsed_args
-
-    if {[catch {
-	set parse_args [concat --default HEAD $rargs]
-	set parsed_args [split [eval exec git-rev-parse $parse_args] "\n"]
-    }]} {
-	# if git-rev-parse failed for some reason...
-	if {$rargs == {}} {
-	    set rargs HEAD
-	}
-	set parsed_args $rargs
-    }
-    return $parsed_args
-}
-
 proc start_rev_list {rlargs} {
     global startmsecs nextupdate ncmupdate
     global commfd leftover tclencoding datemode
@@ -46,7 +30,7 @@ proc start_rev_list {rlargs} {
     }
     if {[catch {
 	set commfd [open [concat | git-rev-list --header $order \
-			      --parents --boundary $rlargs] r]
+			      --parents --boundary --default HEAD $rlargs] r]
     } err]} {
 	puts stderr "Error executing git-rev-list: $err"
 	exit 1
@@ -65,7 +49,7 @@ proc getcommits {rargs} {
     global phase canv mainfont
 
     set phase getcommits
-    start_rev_list [parse_args $rargs]
+    start_rev_list $rargs
     $canv delete all
     $canv create text 3 3 -anchor nw -text "Reading commits..." \
 	-font $mainfont -tags textitems
diff --git a/rev-parse.c b/rev-parse.c
index e956cd5ed..7f66ae2db 100644
--- a/rev-parse.c
+++ b/rev-parse.c
@@ -160,6 +160,14 @@ static int show_file(const char *arg)
 	return 0;
 }
 
+static void die_badfile(const char *arg)
+{
+	if (errno != ENOENT)
+		die("'%s': %s", arg, strerror(errno));
+	die("'%s' is ambiguous - revision name or file/directory name?\n"
+	    "Please put '--' before the list of filenames.", arg);
+}
+
 int main(int argc, char **argv)
 {
 	int i, as_is = 0, verify = 0;
@@ -176,7 +184,7 @@ int main(int argc, char **argv)
 		if (as_is) {
 			if (show_file(arg) && as_is < 2)
 				if (lstat(arg, &st) < 0)
-					die("'%s': %s", arg, strerror(errno));
+					die_badfile(arg);
 			continue;
 		}
 		if (!strcmp(arg,"-n")) {
@@ -343,7 +351,7 @@ int main(int argc, char **argv)
 		if (verify)
 			die("Needed a single revision");
 		if (lstat(arg, &st) < 0)
-			die("'%s': %s", arg, strerror(errno));
+			die_badfile(arg);
 	}
 	show_default();
 	if (verify && revs_count != 1)
diff --git a/revision.c b/revision.c
index 113dd5a89..f9c7d15f5 100644
--- a/revision.c
+++ b/revision.c
@@ -789,7 +789,8 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 	}
 	if (revs->combine_merges) {
 		revs->ignore_merges = 0;
-		if (revs->dense_combined_merges)
+		if (revs->dense_combined_merges &&
+		    (revs->diffopt.output_format != DIFF_FORMAT_DIFFSTAT))
 			revs->diffopt.output_format = DIFF_FORMAT_PATCH;
 	}
 	revs->diffopt.abbrev = revs->abbrev;
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 6729a1826..c69706fb3 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -174,6 +174,27 @@ test_expect_success \
     'git-ls-tree -r output for a known tree.' \
     'diff current expected'
 
+# But with -r -t we can have both.
+test_expect_success \
+    'showing tree with git-ls-tree -r -t' \
+    'git-ls-tree -r -t $tree >current'
+cat >expected <<\EOF
+100644 blob f87290f8eb2cbbea7857214459a0739927eab154	path0
+120000 blob 15a98433ae33114b085f3eb3bb03b832b3180a01	path0sym
+040000 tree 58a09c23e2ca152193f2786e06986b7b6712bdbe	path2
+100644 blob 3feff949ed00a62d9f7af97c15cd8a30595e7ac7	path2/file2
+120000 blob d8ce161addc5173867a3c3c730924388daedbc38	path2/file2sym
+040000 tree 21ae8269cacbe57ae09138dcc3a2887f904d02b3	path3
+100644 blob 0aa34cae68d0878578ad119c86ca2b5ed5b28376	path3/file3
+120000 blob 8599103969b43aff7e430efea79ca4636466794f	path3/file3sym
+040000 tree 3c5e5399f3a333eddecce7a9b9465b63f65f51e2	path3/subp3
+100644 blob 00fb5908cb97c2564a9783c0c64087333b3b464f	path3/subp3/file3
+120000 blob 6649a1ebe9e9f1c553b66f5a6e74136a07ccc57c	path3/subp3/file3sym
+EOF
+test_expect_success \
+    'git-ls-tree -r output for a known tree.' \
+    'diff current expected'
+
 ################################################################
 rm .git/index
 test_expect_success \
diff --git a/t/t1001-read-tree-m-2way.sh b/t/t1001-read-tree-m-2way.sh
index d0ed24275..75e4c9a88 100755
--- a/t/t1001-read-tree-m-2way.sh
+++ b/t/t1001-read-tree-m-2way.sh
@@ -37,7 +37,7 @@ compare_change () {
 }
 
 check_cache_at () {
-	clean_if_empty=`git-diff-files "$1"`
+	clean_if_empty=`git-diff-files -- "$1"`
 	case "$clean_if_empty" in
 	'')  echo "$1: clean" ;;
 	?*)  echo "$1: dirty" ;;
diff --git a/t/t1002-read-tree-m-u-2way.sh b/t/t1002-read-tree-m-u-2way.sh
index 861ef4c0c..4d175d8ea 100755
--- a/t/t1002-read-tree-m-u-2way.sh
+++ b/t/t1002-read-tree-m-u-2way.sh
@@ -20,7 +20,7 @@ compare_change () {
 }
 
 check_cache_at () {
-	clean_if_empty=`git-diff-files "$1"`
+	clean_if_empty=`git-diff-files -- "$1"`
 	case "$clean_if_empty" in
 	'')  echo "$1: clean" ;;
 	?*)  echo "$1: dirty" ;;
diff --git a/t/t4010-diff-pathspec.sh b/t/t4010-diff-pathspec.sh
index 8db329d7f..9e1544df9 100755
--- a/t/t4010-diff-pathspec.sh
+++ b/t/t4010-diff-pathspec.sh
@@ -28,7 +28,7 @@ cat >expected <<\EOF
 EOF
 test_expect_success \
     'limit to path should show nothing' \
-    'git-diff-index --cached $tree path >current &&
+    'git-diff-index --cached $tree -- path >current &&
      compare_diff_raw current expected'
 
 cat >expected <<\EOF
@@ -36,7 +36,7 @@ cat >expected <<\EOF
 EOF
 test_expect_success \
     'limit to path1 should show path1/file1' \
-    'git-diff-index --cached $tree path1 >current &&
+    'git-diff-index --cached $tree -- path1 >current &&
      compare_diff_raw current expected'
 
 cat >expected <<\EOF
@@ -44,7 +44,7 @@ cat >expected <<\EOF
 EOF
 test_expect_success \
     'limit to path1/ should show path1/file1' \
-    'git-diff-index --cached $tree path1/ >current &&
+    'git-diff-index --cached $tree -- path1/ >current &&
      compare_diff_raw current expected'
 
 cat >expected <<\EOF
@@ -52,14 +52,14 @@ cat >expected <<\EOF
 EOF
 test_expect_success \
     'limit to file0 should show file0' \
-    'git-diff-index --cached $tree file0 >current &&
+    'git-diff-index --cached $tree -- file0 >current &&
      compare_diff_raw current expected'
 
 cat >expected <<\EOF
 EOF
 test_expect_success \
     'limit to file0/ should emit nothing.' \
-    'git-diff-index --cached $tree file0/ >current &&
+    'git-diff-index --cached $tree -- file0/ >current &&
      compare_diff_raw current expected'
 
 test_done
diff --git a/update-index.c b/update-index.c
index d6d3295e3..258a88cbe 100644
--- a/update-index.c
+++ b/update-index.c
@@ -7,6 +7,7 @@
 #include "strbuf.h"
 #include "quote.h"
 #include "cache-tree.h"
+#include "tree-walk.h"
 
 /*
  * Default to not allowing changes to the list of files. The
@@ -337,7 +338,7 @@ static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 	return 0;
 }
 
-static int chmod_path(int flip, const char *path)
+static void chmod_path(int flip, const char *path)
 {
 	int pos;
 	struct cache_entry *ce;
@@ -345,22 +346,25 @@ static int chmod_path(int flip, const char *path)
 
 	pos = cache_name_pos(path, strlen(path));
 	if (pos < 0)
-		return -1;
+		goto fail;
 	ce = active_cache[pos];
 	mode = ntohl(ce->ce_mode);
 	if (!S_ISREG(mode))
-		return -1;
+		goto fail;
 	switch (flip) {
 	case '+':
 		ce->ce_mode |= htonl(0111); break;
 	case '-':
 		ce->ce_mode &= htonl(~0111); break;
 	default:
-		return -1;
+		goto fail;
 	}
 	cache_tree_invalidate_path(active_cache_tree, path);
 	active_cache_changed = 1;
-	return 0;
+	report("chmod %cx '%s'", flip, path);
+	return;
+ fail:
+	die("git-update-index: cannot chmod %cx '%s'", flip, path);
 }
 
 static struct cache_file cache_file;
@@ -483,6 +487,124 @@ static void read_index_info(int line_termination)
 static const char update_index_usage[] =
 "git-update-index [-q] [--add] [--replace] [--remove] [--unmerged] [--refresh] [--cacheinfo] [--chmod=(+|-)x] [--info-only] [--force-remove] [--stdin] [--index-info] [--ignore-missing] [-z] [--verbose] [--] <file>...";
 
+static unsigned char head_sha1[20];
+static unsigned char merge_head_sha1[20];
+
+static struct cache_entry *read_one_ent(const char *which,
+					unsigned char *ent, const char *path,
+					int namelen, int stage)
+{
+	unsigned mode;
+	unsigned char sha1[20];
+	int size;
+	struct cache_entry *ce;
+
+	if (get_tree_entry(ent, path, sha1, &mode)) {
+		error("%s: not in %s branch.", path, which);
+		return NULL;
+	}
+	if (mode == S_IFDIR) {
+		error("%s: not a blob in %s branch.", path, which);
+		return NULL;
+	}
+	size = cache_entry_size(namelen);
+	ce = xcalloc(1, size);
+
+	memcpy(ce->sha1, sha1, 20);
+	memcpy(ce->name, path, namelen);
+	ce->ce_flags = create_ce_flags(namelen, stage);
+	ce->ce_mode = create_ce_mode(mode);
+	return ce;
+}
+
+static int unresolve_one(const char *path)
+{
+	int namelen = strlen(path);
+	int pos;
+	int ret = 0;
+	struct cache_entry *ce_2 = NULL, *ce_3 = NULL;
+
+	/* See if there is such entry in the index. */
+	pos = cache_name_pos(path, namelen);
+	if (pos < 0) {
+		/* If there isn't, either it is unmerged, or
+		 * resolved as "removed" by mistake.  We do not
+		 * want to do anything in the former case.
+		 */
+		pos = -pos-1;
+		if (pos < active_nr) {
+			struct cache_entry *ce = active_cache[pos];
+			if (ce_namelen(ce) == namelen &&
+			    !memcmp(ce->name, path, namelen)) {
+				fprintf(stderr,
+					"%s: skipping still unmerged path.\n",
+					path);
+				goto free_return;
+			}
+		}
+	}
+
+	/* Grab blobs from given path from HEAD and MERGE_HEAD,
+	 * stuff HEAD version in stage #2,
+	 * stuff MERGE_HEAD version in stage #3.
+	 */
+	ce_2 = read_one_ent("our", head_sha1, path, namelen, 2);
+	ce_3 = read_one_ent("their", merge_head_sha1, path, namelen, 3);
+
+	if (!ce_2 || !ce_3) {
+		ret = -1;
+		goto free_return;
+	}
+	if (!memcmp(ce_2->sha1, ce_3->sha1, 20) &&
+	    ce_2->ce_mode == ce_3->ce_mode) {
+		fprintf(stderr, "%s: identical in both, skipping.\n",
+			path);
+		goto free_return;
+	}
+
+	remove_file_from_cache(path);
+	if (add_cache_entry(ce_2, ADD_CACHE_OK_TO_ADD)) {
+		error("%s: cannot add our version to the index.", path);
+		ret = -1;
+		goto free_return;
+	}
+	if (!add_cache_entry(ce_3, ADD_CACHE_OK_TO_ADD))
+		return 0;
+	error("%s: cannot add their version to the index.", path);
+	ret = -1;
+ free_return:
+	free(ce_2);
+	free(ce_3);
+	return ret;
+}
+
+static void read_head_pointers(void)
+{
+	if (read_ref(git_path("HEAD"), head_sha1))
+		die("No HEAD -- no initial commit yet?\n");
+	if (read_ref(git_path("MERGE_HEAD"), merge_head_sha1)) {
+		fprintf(stderr, "Not in the middle of a merge.\n");
+		exit(0);
+	}
+}
+
+static int do_unresolve(int ac, const char **av)
+{
+	int i;
+	int err = 0;
+
+	/* Read HEAD and MERGE_HEAD; if MERGE_HEAD does not exist, we
+	 * are not doing a merge, so exit with success status.
+	 */
+	read_head_pointers();
+
+	for (i = 1; i < ac; i++) {
+		const char *arg = av[i];
+		err |= unresolve_one(arg);
+	}
+	return err;
+}
+
 int main(int argc, const char **argv)
 {
 	int i, newfd, entries, has_errors = 0, line_termination = '\n';
@@ -490,6 +612,7 @@ int main(int argc, const char **argv)
 	int read_from_stdin = 0;
 	const char *prefix = setup_git_directory();
 	int prefix_length = prefix ? strlen(prefix) : 0;
+	char set_executable_bit = 0;
 
 	git_config(git_default_config);
 
@@ -556,8 +679,7 @@ int main(int argc, const char **argv)
 			    !strcmp(path, "--chmod=+x")) {
 				if (argc <= i+1)
 					die("git-update-index: %s <path>", path);
-				if (chmod_path(path[8], argv[++i]))
-					die("git-update-index: %s cannot chmod %s", path, argv[i]);
+				set_executable_bit = path[8];
 				continue;
 			}
 			if (!strcmp(path, "--assume-unchanged")) {
@@ -593,6 +715,12 @@ int main(int argc, const char **argv)
 				read_index_info(line_termination);
 				break;
 			}
+			if (!strcmp(path, "--unresolve")) {
+				has_errors = do_unresolve(argc - i, argv + i);
+				if (has_errors)
+					active_cache_changed = 0;
+				goto finish;
+			}
 			if (!strcmp(path, "--ignore-missing")) {
 				not_new = 1;
 				continue;
@@ -606,6 +734,8 @@ int main(int argc, const char **argv)
 			die("unknown option %s", path);
 		}
 		update_one(path, prefix, prefix_length);
+		if (set_executable_bit)
+			chmod_path(set_executable_bit, path);
 	}
 	if (read_from_stdin) {
 		struct strbuf buf;
@@ -620,10 +750,16 @@ int main(int argc, const char **argv)
 			else
 				path_name = buf.buf;
 			update_one(path_name, prefix, prefix_length);
+			if (set_executable_bit) {
+				const char *p = prefix_path(prefix, prefix_length, path_name);
+				chmod_path(set_executable_bit, p);
+			}
 			if (path_name != buf.buf)
 				free(path_name);
 		}
 	}
+
+ finish:
 	if (active_cache_changed) {
 		if (write_cache(newfd, active_cache, active_nr) ||
 		    commit_index_file(&cache_file))