git-add --intent-to-add (-N)

This adds "--intent-to-add" option to "git add".  This is to let the
system know that you will tell it the final contents to be staged later,
iow, just be aware of the presense of the path with the type of the blob
for now.  It is implemented by staging an empty blob as the content.

With this sequence:

    $ git reset --hard
    $ edit newfile
    $ git add -N newfile
    $ edit newfile oldfile
    $ git diff

the diff will show all changes relative to the current commit.  Then you
can do:

    $ git commit -a ;# commit everything

or

    $ git commit oldfile ;# only oldfile, newfile not yet added

to pretend you are working with an index-free system like CVS.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 24 insertions, 5 deletions

diff --git a/read-cache.c b/read-cache.c
index 5150c1e14..276b09e66 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -13,6 +13,7 @@
 #include "diff.h"
 #include "diffcore.h"
 #include "revision.h"
+#include "blob.h"
 
 /* Index extensions.
  *
@@ -511,6 +512,14 @@ static struct cache_entry *create_alias_ce(struct cache_entry *ce, struct cache_
 	return new;
 }
 
+static void record_intent_to_add(struct cache_entry *ce)
+{
+	unsigned char sha1[20];
+	if (write_sha1_file("", 0, blob_type, sha1))
+		die("cannot create an empty blob in the object database");
+	hashcpy(ce->sha1, sha1);
+}
+
 int add_to_index(struct index_state *istate, const char *path, struct stat *st, int flags)
 {
 	int size, namelen, was_same;
@@ -519,6 +528,9 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 	unsigned ce_option = CE_MATCH_IGNORE_VALID|CE_MATCH_RACY_IS_DIRTY;
 	int verbose = flags & (ADD_CACHE_VERBOSE | ADD_CACHE_PRETEND);
 	int pretend = flags & ADD_CACHE_PRETEND;
+	int intent_only = flags & ADD_CACHE_INTENT;
+	int add_option = (ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|
+			  (intent_only ? ADD_CACHE_NEW_ONLY : 0));
 
 	if (!S_ISREG(st_mode) && !S_ISLNK(st_mode) && !S_ISDIR(st_mode))
 		return error("%s: can only add regular files, symbolic links or git-directories", path);
@@ -532,7 +544,8 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 	ce = xcalloc(1, size);
 	memcpy(ce->name, path, namelen);
 	ce->ce_flags = namelen;
-	fill_stat_cache_info(ce, st);
+	if (!intent_only)
+		fill_stat_cache_info(ce, st);
 
 	if (trust_executable_bit && has_symlinks)
 		ce->ce_mode = create_ce_mode(st_mode);
@@ -555,8 +568,12 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 		alias->ce_flags |= CE_ADDED;
 		return 0;
 	}
-	if (index_path(ce->sha1, path, st, 1))
-		return error("unable to index file %s", path);
+	if (!intent_only) {
+		if (index_path(ce->sha1, path, st, 1))
+			return error("unable to index file %s", path);
+	} else
+		record_intent_to_add(ce);
+
 	if (ignore_case && alias && different_name(ce, alias))
 		ce = create_alias_ce(ce, alias);
 	ce->ce_flags |= CE_ADDED;
@@ -569,7 +586,7 @@ int add_to_index(struct index_state *istate, const char *path, struct stat *st,
 
 	if (pretend)
 		;
-	else if (add_index_entry(istate, ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE))
+	else if (add_index_entry(istate, ce, add_option))
 		return error("unable to add %s to index",path);
 	if (verbose && !was_same)
 		printf("add '%s'\n", path);
@@ -848,13 +865,15 @@ static int add_index_entry_with_check(struct index_state *istate, struct cache_e
 	int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
 	int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
 	int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
+	int new_only = option & ADD_CACHE_NEW_ONLY;
 
 	cache_tree_invalidate_path(istate->cache_tree, ce->name);
 	pos = index_name_pos(istate, ce->name, ce->ce_flags);
 
 	/* existing match? Just replace it. */
 	if (pos >= 0) {
-		replace_index_entry(istate, pos, ce);
+		if (!new_only)
+			replace_index_entry(istate, pos, ce);
 		return 0;
 	}
 	pos = -pos-1;