Merge branch 'jk/diff'

* jk/diff:
  wt-status: remove extraneous newline from 'deleted:' output
  git-status: document colorization config options
  Teach runstatus about --untracked
  git-commit.sh: convert run_status to a C builtin
  Move color option parsing out of diff.c and into color.[ch]
  diff: support custom callbacks for output

15 files changed, 576 insertions, 232 deletions

diff --git a/.gitignore b/.gitignore
index 90d6d7c66..a3d9c7a11 100644
--- a/.gitignore
+++ b/.gitignore
@@ -95,6 +95,7 @@ git-rev-list
 git-rev-parse
 git-revert
 git-rm
+git-runstatus
 git-send-email
 git-send-pack
 git-sh-setup
diff --git a/Documentation/config.txt b/Documentation/config.txt
index ce722a2db..844cae4cf 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -225,6 +225,20 @@ showbranch.default::
 	The default set of branches for gitlink:git-show-branch[1].
 	See gitlink:git-show-branch[1].
 
+status.color::
+	A boolean to enable/disable color in the output of
+	gitlink:git-status[1]. May be set to `true` (or `always`),
+	`false` (or `never`) or `auto`, in which case colors are used
+	only when the output is to a terminal. Defaults to false.
+
+status.color.<slot>::
+	Use customized color for status colorization. `<slot>` is
+	one of `header` (the header text of the status message),
+	`updated` (files which are updated but not committed),
+	`changed` (files which are changed but not updated in the index),
+	or `untracked` (files which are not tracked by git). The values of
+	these variables may be specified as in diff.color.<slot>.
+
 tar.umask::
 	By default, gitlink:git-tar-tree[1] sets file and directories modes
 	to 0666 or 0777. While this is both useful and acceptable for projects
diff --git a/Makefile b/Makefile
index b98745045..69915d865 100644
--- a/Makefile
+++ b/Makefile
@@ -253,7 +253,8 @@ LIB_OBJS = \
 	tag.o tree.o usage.o config.o environment.o ctype.o copy.o \
 	fetch-clone.o revision.o pager.o tree-walk.o xdiff-interface.o \
 	write_or_die.o trace.o \
-	alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS)
+	alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS) \
+	color.o wt-status.o
 
 BUILTIN_OBJS = \
 	builtin-add.o \
@@ -288,6 +289,7 @@ BUILTIN_OBJS = \
 	builtin-rev-list.o \
 	builtin-rev-parse.o \
 	builtin-rm.o \
+	builtin-runstatus.o \
 	builtin-show-branch.o \
 	builtin-stripspace.o \
 	builtin-symbolic-ref.o \
diff --git a/builtin-runstatus.c b/builtin-runstatus.c
new file mode 100644
index 000000000..303c556da
--- /dev/null
+++ b/builtin-runstatus.c
@@ -0,0 +1,36 @@
+#include "wt-status.h"
+#include "cache.h"
+
+extern int wt_status_use_color;
+
+static const char runstatus_usage[] =
+"git-runstatus [--color|--nocolor] [--amend] [--verbose]";
+
+int cmd_runstatus(int argc, const char **argv, const char *prefix)
+{
+	struct wt_status s;
+	int i;
+
+	git_config(git_status_config);
+	wt_status_prepare(&s);
+
+	for (i = 1; i < argc; i++) {
+		if (!strcmp(argv[i], "--color"))
+			wt_status_use_color = 1;
+		else if (!strcmp(argv[i], "--nocolor"))
+			wt_status_use_color = 0;
+		else if (!strcmp(argv[i], "--amend")) {
+			s.amend = 1;
+			s.reference = "HEAD^1";
+		}
+		else if (!strcmp(argv[i], "--verbose"))
+			s.verbose = 1;
+		else if (!strcmp(argv[i], "--untracked"))
+			s.untracked = 1;
+		else
+			usage(runstatus_usage);
+	}
+
+	wt_status_print(&s);
+	return s.commitable ? 0 : 1;
+}
diff --git a/builtin.h b/builtin.h
index 37a8c875a..ccade94e2 100644
--- a/builtin.h
+++ b/builtin.h
@@ -47,6 +47,7 @@ extern int cmd_repo_config(int argc, const char **argv, const char *prefix);
 extern int cmd_rev_list(int argc, const char **argv, const char *prefix);
 extern int cmd_rev_parse(int argc, const char **argv, const char *prefix);
 extern int cmd_rm(int argc, const char **argv, const char *prefix);
+extern int cmd_runstatus(int argc, const char **argv, const char *prefix);
 extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
 extern int cmd_show(int argc, const char **argv, const char *prefix);
 extern int cmd_stripspace(int argc, const char **argv, const char *prefix);
diff --git a/color.c b/color.c
new file mode 100644
index 000000000..d8c8399d5
--- /dev/null
+++ b/color.c
@@ -0,0 +1,176 @@
+#include "color.h"
+#include "cache.h"
+#include "git-compat-util.h"
+
+#include <stdarg.h>
+
+#define COLOR_RESET "\033[m"
+
+static int parse_color(const char *name, int len)
+{
+	static const char * const color_names[] = {
+		"normal", "black", "red", "green", "yellow",
+		"blue", "magenta", "cyan", "white"
+	};
+	char *end;
+	int i;
+	for (i = 0; i < ARRAY_SIZE(color_names); i++) {
+		const char *str = color_names[i];
+		if (!strncasecmp(name, str, len) && !str[len])
+			return i - 1;
+	}
+	i = strtol(name, &end, 10);
+	if (*name && !*end && i >= -1 && i <= 255)
+		return i;
+	return -2;
+}
+
+static int parse_attr(const char *name, int len)
+{
+	static const int attr_values[] = { 1, 2, 4, 5, 7 };
+	static const char * const attr_names[] = {
+		"bold", "dim", "ul", "blink", "reverse"
+	};
+	int i;
+	for (i = 0; i < ARRAY_SIZE(attr_names); i++) {
+		const char *str = attr_names[i];
+		if (!strncasecmp(name, str, len) && !str[len])
+			return attr_values[i];
+	}
+	return -1;
+}
+
+void color_parse(const char *value, const char *var, char *dst)
+{
+	const char *ptr = value;
+	int attr = -1;
+	int fg = -2;
+	int bg = -2;
+
+	if (!strcasecmp(value, "reset")) {
+		strcpy(dst, "\033[m");
+		return;
+	}
+
+	/* [fg [bg]] [attr] */
+	while (*ptr) {
+		const char *word = ptr;
+		int val, len = 0;
+
+		while (word[len] && !isspace(word[len]))
+			len++;
+
+		ptr = word + len;
+		while (*ptr && isspace(*ptr))
+			ptr++;
+
+		val = parse_color(word, len);
+		if (val >= -1) {
+			if (fg == -2) {
+				fg = val;
+				continue;
+			}
+			if (bg == -2) {
+				bg = val;
+				continue;
+			}
+			goto bad;
+		}
+		val = parse_attr(word, len);
+		if (val < 0 || attr != -1)
+			goto bad;
+		attr = val;
+	}
+
+	if (attr >= 0 || fg >= 0 || bg >= 0) {
+		int sep = 0;
+
+		*dst++ = '\033';
+		*dst++ = '[';
+		if (attr >= 0) {
+			*dst++ = '0' + attr;
+			sep++;
+		}
+		if (fg >= 0) {
+			if (sep++)
+				*dst++ = ';';
+			if (fg < 8) {
+				*dst++ = '3';
+				*dst++ = '0' + fg;
+			} else {
+				dst += sprintf(dst, "38;5;%d", fg);
+			}
+		}
+		if (bg >= 0) {
+			if (sep++)
+				*dst++ = ';';
+			if (bg < 8) {
+				*dst++ = '4';
+				*dst++ = '0' + bg;
+			} else {
+				dst += sprintf(dst, "48;5;%d", bg);
+			}
+		}
+		*dst++ = 'm';
+	}
+	*dst = 0;
+	return;
+bad:
+	die("bad config value '%s' for variable '%s'", value, var);
+}
+
+int git_config_colorbool(const char *var, const char *value)
+{
+	if (!value)
+		return 1;
+	if (!strcasecmp(value, "auto")) {
+		if (isatty(1) || (pager_in_use && pager_use_color)) {
+			char *term = getenv("TERM");
+			if (term && strcmp(term, "dumb"))
+				return 1;
+		}
+		return 0;
+	}
+	if (!strcasecmp(value, "never"))
+		return 0;
+	if (!strcasecmp(value, "always"))
+		return 1;
+	return git_config_bool(var, value);
+}
+
+static int color_vprintf(const char *color, const char *fmt,
+		va_list args, const char *trail)
+{
+	int r = 0;
+
+	if (*color)
+		r += printf("%s", color);
+	r += vprintf(fmt, args);
+	if (*color)
+		r += printf("%s", COLOR_RESET);
+	if (trail)
+		r += printf("%s", trail);
+	return r;
+}
+
+
+
+int color_printf(const char *color, const char *fmt, ...)
+{
+	va_list args;
+	int r;
+	va_start(args, fmt);
+	r = color_vprintf(color, fmt, args, NULL);
+	va_end(args);
+	return r;
+}
+
+int color_printf_ln(const char *color, const char *fmt, ...)
+{
+	va_list args;
+	int r;
+	va_start(args, fmt);
+	r = color_vprintf(color, fmt, args, "\n");
+	va_end(args);
+	return r;
+}
diff --git a/color.h b/color.h
new file mode 100644
index 000000000..88bb8ff1b
--- /dev/null
+++ b/color.h
@@ -0,0 +1,12 @@
+#ifndef COLOR_H
+#define COLOR_H
+
+/* "\033[1;38;5;2xx;48;5;2xxm\0" is 23 bytes */
+#define COLOR_MAXLEN 24
+
+int git_config_colorbool(const char *var, const char *value);
+void color_parse(const char *var, const char *value, char *dst);
+int color_printf(const char *color, const char *fmt, ...);
+int color_printf_ln(const char *color, const char *fmt, ...);
+
+#endif /* COLOR_H */
diff --git a/diff.c b/diff.c
index 663886570..443e24861 100644
--- a/diff.c
+++ b/diff.c
@@ -10,6 +10,7 @@
 #include "diffcore.h"
 #include "delta.h"
 #include "xdiff-interface.h"
+#include "color.h"
 
 static int use_size_cache;
 
@@ -17,8 +18,7 @@ static int diff_detect_rename_default;
 static int diff_rename_limit_default = -1;
 static int diff_use_color_default;
 
-/* "\033[1;38;5;2xx;48;5;2xxm\0" is 23 bytes */
-static char diff_colors[][24] = {
+static char diff_colors[][COLOR_MAXLEN] = {
 	"\033[m",	/* reset */
 	"",		/* normal */
 	"\033[1m",	/* bold */
@@ -45,119 +45,6 @@ static int parse_diff_color_slot(const char *var, int ofs)
 	die("bad config variable '%s'", var);
 }
 
-static int parse_color(const char *name, int len)
-{
-	static const char * const color_names[] = {
-		"normal", "black", "red", "green", "yellow",
-		"blue", "magenta", "cyan", "white"
-	};
-	char *end;
-	int i;
-	for (i = 0; i < ARRAY_SIZE(color_names); i++) {
-		const char *str = color_names[i];
-		if (!strncasecmp(name, str, len) && !str[len])
-			return i - 1;
-	}
-	i = strtol(name, &end, 10);
-	if (*name && !*end && i >= -1 && i <= 255)
-		return i;
-	return -2;
-}
-
-static int parse_attr(const char *name, int len)
-{
-	static const int attr_values[] = { 1, 2, 4, 5, 7 };
-	static const char * const attr_names[] = {
-		"bold", "dim", "ul", "blink", "reverse"
-	};
-	int i;
-	for (i = 0; i < ARRAY_SIZE(attr_names); i++) {
-		const char *str = attr_names[i];
-		if (!strncasecmp(name, str, len) && !str[len])
-			return attr_values[i];
-	}
-	return -1;
-}
-
-static void parse_diff_color_value(const char *value, const char *var, char *dst)
-{
-	const char *ptr = value;
-	int attr = -1;
-	int fg = -2;
-	int bg = -2;
-
-	if (!strcasecmp(value, "reset")) {
-		strcpy(dst, "\033[m");
-		return;
-	}
-
-	/* [fg [bg]] [attr] */
-	while (*ptr) {
-		const char *word = ptr;
-		int val, len = 0;
-
-		while (word[len] && !isspace(word[len]))
-			len++;
-
-		ptr = word + len;
-		while (*ptr && isspace(*ptr))
-			ptr++;
-
-		val = parse_color(word, len);
-		if (val >= -1) {
-			if (fg == -2) {
-				fg = val;
-				continue;
-			}
-			if (bg == -2) {
-				bg = val;
-				continue;
-			}
-			goto bad;
-		}
-		val = parse_attr(word, len);
-		if (val < 0 || attr != -1)
-			goto bad;
-		attr = val;
-	}
-
-	if (attr >= 0 || fg >= 0 || bg >= 0) {
-		int sep = 0;
-
-		*dst++ = '\033';
-		*dst++ = '[';
-		if (attr >= 0) {
-			*dst++ = '0' + attr;
-			sep++;
-		}
-		if (fg >= 0) {
-			if (sep++)
-				*dst++ = ';';
-			if (fg < 8) {
-				*dst++ = '3';
-				*dst++ = '0' + fg;
-			} else {
-				dst += sprintf(dst, "38;5;%d", fg);
-			}
-		}
-		if (bg >= 0) {
-			if (sep++)
-				*dst++ = ';';
-			if (bg < 8) {
-				*dst++ = '4';
-				*dst++ = '0' + bg;
-			} else {
-				dst += sprintf(dst, "48;5;%d", bg);
-			}
-		}
-		*dst++ = 'm';
-	}
-	*dst = 0;
-	return;
-bad:
-	die("bad config value '%s' for variable '%s'", value, var);
-}
-
 /*
  * These are to give UI layer defaults.
  * The core-level commands such as git-diff-files should
@@ -171,22 +58,7 @@ int git_diff_ui_config(const char *var, const char *value)
 		return 0;
 	}
 	if (!strcmp(var, "diff.color")) {
-		if (!value)
-			diff_use_color_default = 1; /* bool */
-		else if (!strcasecmp(value, "auto")) {
-			diff_use_color_default = 0;
-			if (isatty(1) || (pager_in_use && pager_use_color)) {
-				char *term = getenv("TERM");
-				if (term && strcmp(term, "dumb"))
-					diff_use_color_default = 1;
-			}
-		}
-		else if (!strcasecmp(value, "never"))
-			diff_use_color_default = 0;
-		else if (!strcasecmp(value, "always"))
-			diff_use_color_default = 1;
-		else
-			diff_use_color_default = git_config_bool(var, value);
+		diff_use_color_default = git_config_colorbool(var, value);
 		return 0;
 	}
 	if (!strcmp(var, "diff.renames")) {
@@ -201,7 +73,7 @@ int git_diff_ui_config(const char *var, const char *value)
 	}
 	if (!strncmp(var, "diff.color.", 11)) {
 		int slot = parse_diff_color_slot(var, 11);
-		parse_diff_color_value(value, var, diff_colors[slot]);
+		color_parse(value, var, diff_colors[slot]);
 		return 0;
 	}
 	return git_default_config(var, value);
@@ -2593,6 +2465,9 @@ void diff_flush(struct diff_options *options)
 		}
 	}
 
+	if (output_format & DIFF_FORMAT_CALLBACK)
+		options->format_callback(q, options, options->format_callback_data);
+
 	for (i = 0; i < q->nr; i++)
 		diff_free_filepair(q->queue[i]);
 free_queue:
diff --git a/diff.h b/diff.h
index b007240a5..b60a02e62 100644
--- a/diff.h
+++ b/diff.h
@@ -8,6 +8,7 @@
 
 struct rev_info;
 struct diff_options;
+struct diff_queue_struct;
 
 typedef void (*change_fn_t)(struct diff_options *options,
 		 unsigned old_mode, unsigned new_mode,
@@ -20,6 +21,9 @@ typedef void (*add_remove_fn_t)(struct diff_options *options,
 		    const unsigned char *sha1,
 		    const char *base, const char *path);
 
+typedef void (*diff_format_fn_t)(struct diff_queue_struct *q,
+		struct diff_options *options, void *data);
+
 #define DIFF_FORMAT_RAW		0x0001
 #define DIFF_FORMAT_DIFFSTAT	0x0002
 #define DIFF_FORMAT_SUMMARY	0x0004
@@ -35,6 +39,8 @@ typedef void (*add_remove_fn_t)(struct diff_options *options,
  */
 #define DIFF_FORMAT_NO_OUTPUT	0x0080
 
+#define DIFF_FORMAT_CALLBACK	0x0100
+
 struct diff_options {
 	const char *filter;
 	const char *orderfile;
@@ -68,6 +74,8 @@ struct diff_options {
 	int *pathlens;
 	change_fn_t change;
 	add_remove_fn_t add_remove;
+	diff_format_fn_t format_callback;
+	void *format_callback_data;
 };
 
 enum color_diff {
diff --git a/dir.c b/dir.c
index 5a40d8ff8..e2f472ba7 100644
--- a/dir.c
+++ b/dir.c
@@ -397,3 +397,10 @@ int read_directory(struct dir_struct *dir, const char *path, const char *base, i
 	qsort(dir->entries, dir->nr, sizeof(struct dir_entry *), cmp_name);
 	return dir->nr;
 }
+
+int
+file_exists(const char *f)
+{
+  struct stat sb;
+  return stat(f, &sb) == 0;
+}
diff --git a/dir.h b/dir.h
index 56a1b7fce..313f8ab64 100644
--- a/dir.h
+++ b/dir.h
@@ -47,5 +47,6 @@ extern int excluded(struct dir_struct *, const char *);
 extern void add_excludes_from_file(struct dir_struct *, const char *fname);
 extern void add_exclude(const char *string, const char *base,
 			int baselen, struct exclude_list *which);
+extern int file_exists(const char *);
 
 #endif
diff --git a/git-commit.sh b/git-commit.sh
index 4cf3fab05..5a4c659b6 100755
--- a/git-commit.sh
+++ b/git-commit.sh
@@ -60,26 +60,6 @@ report () {
 }
 
 run_status () {
-    (
-	# We always show status for the whole tree.
-	cd "$TOP"
-
-	IS_INITIAL="$initial_commit"
-	REFERENCE=HEAD
-	case "$amend" in
-	t)
-		# If we are amending the initial commit, there
-		# is no HEAD^1.
-		if git-rev-parse --verify "HEAD^1" >/dev/null 2>&1
-		then
-			REFERENCE="HEAD^1"
-			IS_INITIAL=
-		else
-			IS_INITIAL=t
-		fi
-		;;
-	esac
-
 	# If TMP_INDEX is defined, that means we are doing
 	# "--only" partial commit, and that index file is used
 	# to build the tree for the commit.  Otherwise, if
@@ -96,85 +76,14 @@ run_status () {
 	    export GIT_INDEX_FILE
 	fi
 
-	case "$branch" in
-	refs/heads/master) ;;
-	*)  echo "# On branch $branch" ;;
-	esac
-
-	if test -z "$IS_INITIAL"
-	then
-	    git-diff-index -M --cached --name-status \
-		--diff-filter=MDTCRA $REFERENCE |
-	    sed -e '
-		    s/\\/\\\\/g
-		    s/ /\\ /g
-	    ' |
-	    report "Updated but not checked in" "will commit"
-	    committable="$?"
-	else
-	    echo '#
-# Initial commit
-#'
-	    git-ls-files |
-	    sed -e '
-		    s/\\/\\\\/g
-		    s/ /\\ /g
-		    s/^/A /
-	    ' |
-	    report "Updated but not checked in" "will commit"
-
-	    committable="$?"
-	fi
-
-	git-diff-files  --name-status |
-	sed -e '
-		s/\\/\\\\/g
-		s/ /\\ /g
-	' |
-	report "Changed but not updated" \
-	    "use git-update-index to mark for commit"
-
-        option=""
-        if test -z "$untracked_files"; then
-            option="--directory --no-empty-directory"
-        fi
-	hdr_shown=
-	if test -f "$GIT_DIR/info/exclude"
-	then
-	    git-ls-files --others $option \
-		--exclude-from="$GIT_DIR/info/exclude" \
-		--exclude-per-directory=.gitignore
-	else
-	    git-ls-files --others $option \
-		--exclude-per-directory=.gitignore
-	fi |
-	while read line; do
-	    if [ -z "$hdr_shown" ]; then
-		echo '#'
-		echo '# Untracked files:'
-		echo '#   (use "git add" to add to commit)'
-		echo '#'
-		hdr_shown=1
-	    fi
-	    echo "#	$line"
-	done
-
-	if test -n "$verbose" -a -z "$IS_INITIAL"
-	then
-	    git-diff-index --cached -M -p --diff-filter=MDTCRA $REFERENCE
-	fi
-	case "$committable" in
-	0)
-		case "$amend" in
-		t)
-			echo "# No changes" ;;
-		*)
-			echo "nothing to commit" ;;
-		esac
-		exit 1 ;;
-	esac
-	exit 0
-    )
+  case "$status_only" in
+    t) color= ;;
+    *) color=--nocolor ;;
+  esac
+  git-runstatus ${color} \
+                ${verbose:+--verbose} \
+                ${amend:+--amend} \
+		${untracked_files:+--untracked}
 }
 
 trap '
diff --git a/git.c b/git.c
index 70cafb026..44ab0de94 100644
--- a/git.c
+++ b/git.c
@@ -253,6 +253,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "rev-list", cmd_rev_list, RUN_SETUP },
 		{ "rev-parse", cmd_rev_parse, RUN_SETUP },
 		{ "rm", cmd_rm, RUN_SETUP },
+		{ "runstatus", cmd_runstatus, RUN_SETUP },
 		{ "show-branch", cmd_show_branch, RUN_SETUP },
 		{ "show", cmd_show, RUN_SETUP | USE_PAGER },
 		{ "stripspace", cmd_stripspace },
diff --git a/wt-status.c b/wt-status.c
new file mode 100644
index 000000000..4b74e6858
--- /dev/null
+++ b/wt-status.c
@@ -0,0 +1,276 @@
+#include "wt-status.h"
+#include "color.h"
+#include "cache.h"
+#include "object.h"
+#include "dir.h"
+#include "commit.h"
+#include "diff.h"
+#include "revision.h"
+#include "diffcore.h"
+
+int wt_status_use_color = 0;
+static char wt_status_colors[][COLOR_MAXLEN] = {
+	"",         /* WT_STATUS_HEADER: normal */
+	"\033[32m", /* WT_STATUS_UPDATED: green */
+	"\033[31m", /* WT_STATUS_CHANGED: red */
+	"\033[31m", /* WT_STATUS_UNTRACKED: red */
+};
+
+static int parse_status_slot(const char *var, int offset)
+{
+	if (!strcasecmp(var+offset, "header"))
+		return WT_STATUS_HEADER;
+	if (!strcasecmp(var+offset, "updated"))
+		return WT_STATUS_UPDATED;
+	if (!strcasecmp(var+offset, "changed"))
+		return WT_STATUS_CHANGED;
+	if (!strcasecmp(var+offset, "untracked"))
+		return WT_STATUS_UNTRACKED;
+	die("bad config variable '%s'", var);
+}
+
+static const char* color(int slot)
+{
+	return wt_status_use_color ? wt_status_colors[slot] : "";
+}
+
+void wt_status_prepare(struct wt_status *s)
+{
+	unsigned char sha1[20];
+	const char *head;
+
+	s->is_initial = get_sha1("HEAD", sha1) ? 1 : 0;
+
+	head = resolve_ref(git_path("HEAD"), sha1, 0);
+	s->branch = head ?
+		    strdup(head + strlen(get_git_dir()) + 1) :
+		    NULL;
+
+	s->reference = "HEAD";
+	s->amend = 0;
+	s->verbose = 0;
+	s->commitable = 0;
+	s->untracked = 0;
+}
+
+static void wt_status_print_header(const char *main, const char *sub)
+{
+	const char *c = color(WT_STATUS_HEADER);
+	color_printf_ln(c, "# %s:", main);
+	color_printf_ln(c, "#   (%s)", sub);
+	color_printf_ln(c, "#");
+}
+
+static void wt_status_print_trailer(void)
+{
+	color_printf_ln(color(WT_STATUS_HEADER), "#");
+}
+
+static void wt_status_print_filepair(int t, struct diff_filepair *p)
+{
+	const char *c = color(t);
+	color_printf(color(WT_STATUS_HEADER), "#\t");
+	switch (p->status) {
+	case DIFF_STATUS_ADDED:
+		color_printf(c, "new file: %s", p->one->path); break;
+	case DIFF_STATUS_COPIED:
+		color_printf(c, "copied: %s -> %s",
+				p->one->path, p->two->path);
+		break;
+	case DIFF_STATUS_DELETED:
+		color_printf(c, "deleted: %s", p->one->path); break;
+	case DIFF_STATUS_MODIFIED:
+		color_printf(c, "modified: %s", p->one->path); break;
+	case DIFF_STATUS_RENAMED:
+		color_printf(c, "renamed: %s -> %s",
+				p->one->path, p->two->path);
+		break;
+	case DIFF_STATUS_TYPE_CHANGED:
+		color_printf(c, "typechange: %s", p->one->path); break;
+	case DIFF_STATUS_UNKNOWN:
+		color_printf(c, "unknown: %s", p->one->path); break;
+	case DIFF_STATUS_UNMERGED:
+		color_printf(c, "unmerged: %s", p->one->path); break;
+	default:
+		die("bug: unhandled diff status %c", p->status);
+	}
+	printf("\n");
+}
+
+static void wt_status_print_updated_cb(struct diff_queue_struct *q,
+		struct diff_options *options,
+		void *data)
+{
+	struct wt_status *s = data;
+	int shown_header = 0;
+	int i;
+	if (q->nr) {
+	}
+	for (i = 0; i < q->nr; i++) {
+		if (q->queue[i]->status == 'U')
+			continue;
+		if (!shown_header) {
+			wt_status_print_header("Updated but not checked in",
+					"will commit");
+			s->commitable = 1;
+			shown_header = 1;
+		}
+		wt_status_print_filepair(WT_STATUS_UPDATED, q->queue[i]);
+	}
+	if (shown_header)
+		wt_status_print_trailer();
+}
+
+static void wt_status_print_changed_cb(struct diff_queue_struct *q,
+                        struct diff_options *options,
+                        void *data)
+{
+	int i;
+	if (q->nr)
+		wt_status_print_header("Changed but not updated",
+				"use git-update-index to mark for commit");
+	for (i = 0; i < q->nr; i++)
+		wt_status_print_filepair(WT_STATUS_CHANGED, q->queue[i]);
+	if (q->nr)
+		wt_status_print_trailer();
+}
+
+void wt_status_print_initial(struct wt_status *s)
+{
+	int i;
+	read_cache();
+	if (active_nr) {
+		s->commitable = 1;
+		wt_status_print_header("Updated but not checked in",
+				"will commit");
+	}
+	for (i = 0; i < active_nr; i++) {
+		color_printf(color(WT_STATUS_HEADER), "#\t");
+		color_printf_ln(color(WT_STATUS_UPDATED), "new file: %s",
+				active_cache[i]->name);
+	}
+	if (active_nr)
+		wt_status_print_trailer();
+}
+
+static void wt_status_print_updated(struct wt_status *s)
+{
+	struct rev_info rev;
+	const char *argv[] = { NULL, NULL, NULL };
+	argv[1] = s->reference;
+	init_revisions(&rev, NULL);
+	setup_revisions(2, argv, &rev, NULL);
+	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
+	rev.diffopt.format_callback = wt_status_print_updated_cb;
+	rev.diffopt.format_callback_data = s;
+	rev.diffopt.detect_rename = 1;
+	run_diff_index(&rev, 1);
+}
+
+static void wt_status_print_changed(struct wt_status *s)
+{
+	struct rev_info rev;
+	const char *argv[] = { NULL, NULL };
+	init_revisions(&rev, "");
+	setup_revisions(1, argv, &rev, NULL);
+	rev.diffopt.output_format |= DIFF_FORMAT_CALLBACK;
+	rev.diffopt.format_callback = wt_status_print_changed_cb;
+	rev.diffopt.format_callback_data = s;
+	run_diff_files(&rev, 0);
+}
+
+static void wt_status_print_untracked(const struct wt_status *s)
+{
+	struct dir_struct dir;
+	const char *x;
+	int i;
+	int shown_header = 0;
+
+	memset(&dir, 0, sizeof(dir));
+
+	dir.exclude_per_dir = ".gitignore";
+	if (!s->untracked) {
+		dir.show_other_directories = 1;
+		dir.hide_empty_directories = 1;
+	}
+	x = git_path("info/exclude");
+	if (file_exists(x))
+		add_excludes_from_file(&dir, x);
+
+	read_directory(&dir, ".", "", 0);
+	for(i = 0; i < dir.nr; i++) {
+		/* check for matching entry, which is unmerged; lifted from
+		 * builtin-ls-files:show_other_files */
+		struct dir_entry *ent = dir.entries[i];
+		int pos = cache_name_pos(ent->name, ent->len);
+		struct cache_entry *ce;
+		if (0 <= pos)
+			die("bug in wt_status_print_untracked");
+		pos = -pos - 1;
+		if (pos < active_nr) {
+			ce = active_cache[pos];
+			if (ce_namelen(ce) == ent->len &&
+			    !memcmp(ce->name, ent->name, ent->len))
+				continue;
+		}
+		if (!shown_header) {
+			wt_status_print_header("Untracked files",
+				"use \"git add\" to add to commit");
+			shown_header = 1;
+		}
+		color_printf(color(WT_STATUS_HEADER), "#\t");
+		color_printf_ln(color(WT_STATUS_UNTRACKED), "%.*s",
+				ent->len, ent->name);
+	}
+}
+
+static void wt_status_print_verbose(struct wt_status *s)
+{
+	struct rev_info rev;
+	const char *argv[] = { NULL, NULL, NULL };
+	argv[1] = s->reference;
+	init_revisions(&rev, NULL);
+	setup_revisions(2, argv, &rev, NULL);
+	rev.diffopt.output_format |= DIFF_FORMAT_PATCH;
+	rev.diffopt.detect_rename = 1;
+	run_diff_index(&rev, 1);
+}
+
+void wt_status_print(struct wt_status *s)
+{
+	if (s->branch && strcmp(s->branch, "refs/heads/master"))
+		color_printf_ln(color(WT_STATUS_HEADER),
+			"# On branch %s", s->branch);
+
+	if (s->is_initial) {
+		color_printf_ln(color(WT_STATUS_HEADER), "#");
+		color_printf_ln(color(WT_STATUS_HEADER), "# Initial commit");
+		color_printf_ln(color(WT_STATUS_HEADER), "#");
+		wt_status_print_initial(s);
+	}
+	else {
+		wt_status_print_updated(s);
+		discard_cache();
+	}
+
+	wt_status_print_changed(s);
+	wt_status_print_untracked(s);
+
+	if (s->verbose && !s->is_initial)
+		wt_status_print_verbose(s);
+	if (!s->commitable)
+		printf("%s\n", s->amend ? "# No changes" : "nothing to commit");
+}
+
+int git_status_config(const char *k, const char *v)
+{
+	if (!strcmp(k, "status.color")) {
+		wt_status_use_color = git_config_colorbool(k, v);
+		return 0;
+	}
+	if (!strncmp(k, "status.color.", 13)) {
+		int slot = parse_status_slot(k, 13);
+		color_parse(v, k, wt_status_colors[slot]);
+	}
+	return git_default_config(k, v);
+}
diff --git a/wt-status.h b/wt-status.h
new file mode 100644
index 000000000..0a5a5b7ba
--- /dev/null
+++ b/wt-status.h
@@ -0,0 +1,25 @@
+#ifndef STATUS_H
+#define STATUS_H
+
+enum color_wt_status {
+	WT_STATUS_HEADER,
+	WT_STATUS_UPDATED,
+	WT_STATUS_CHANGED,
+	WT_STATUS_UNTRACKED,
+};
+
+struct wt_status {
+	int is_initial;
+	char *branch;
+	const char *reference;
+	int commitable;
+	int verbose;
+	int amend;
+	int untracked;
+};
+
+int git_status_config(const char *var, const char *value);
+void wt_status_prepare(struct wt_status *s);
+void wt_status_print(struct wt_status *s);
+
+#endif /* STATUS_H */