git add: respect core.filemode with unmerged entries

When a merge left unmerged entries, git add failed to pick up the
file mode from the index, when core.filemode == 0. If more than one
unmerged entry is there, the order of stage preference is 2, 1, 3.

Noticed by Johannes Sixt.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

read-cache.c

@@ -350,6 +350,34 @@ int remove_file_from_index(struct index_state *istate, const char *path)
 	return 0;
 }
 
+static int compare_name(struct cache_entry *ce, const char *path, int namelen)
+{
+	return namelen != ce_namelen(ce) || memcmp(path, ce->name, namelen);
+}
+
+static int index_name_pos_also_unmerged(struct index_state *istate,
+	const char *path, int namelen)
+{
+	int pos = index_name_pos(istate, path, namelen);
+	struct cache_entry *ce;
+
+	if (pos >= 0)
+		return pos;
+
+	/* maybe unmerged? */
+	pos = -1 - pos;
+	if (pos >= istate->cache_nr ||
+			compare_name((ce = istate->cache[pos]), path, namelen))
+		return -1;
+
+	/* order of preference: stage 2, 1, 3 */
+	if (ce_stage(ce) == 1 && pos + 1 < istate->cache_nr &&
+			ce_stage((ce = istate->cache[pos + 1])) == 2 &&
+			!compare_name(ce, path, namelen))
+		pos++;
+	return pos;
+}
+
 int add_file_to_index(struct index_state *istate, const char *path, int verbose)
 {
 	int size, namelen;
@@ -380,7 +408,7 @@ int add_file_to_index(struct index_state *istate, const char *path, int verbose)
 		 * from it, otherwise assume unexecutable regular file.
 		 */
 		struct cache_entry *ent;
-		int pos = index_name_pos(istate, path, namelen);
+		int pos = index_name_pos_also_unmerged(istate, path, namelen);
 
 		ent = (0 <= pos) ? istate->cache[pos] : NULL;
 		ce->ce_mode = ce_mode_from_stat(ent, st.st_mode);

t/t3700-add.sh

@@ -110,4 +110,30 @@ test_expect_success 'check correct prefix detection' '
 	git add 1/2/a 1/3/b 1/2/c
 '
 
+test_expect_success 'git add and filemode=0 with unmerged entries' '
+	echo 1 > stage1 &&
+	echo 2 > stage2 &&
+	echo 3 > stage3 &&
+	for s in 1 2 3
+	do
+		echo "100755 $(git hash-object -w stage$s) $s	file"
+	done | git update-index --index-info &&
+	git config core.filemode 0 &&
+	echo new > file &&
+	git add file &&
+	git ls-files --stage | grep "^100755 .* 0	file$"
+'
+
+test_expect_success 'git add and filemode=0 prefers stage 2 over stage 1' '
+	git rm --cached -f file &&
+	(
+		echo "100644 $(git hash-object -w stage1) 1	file"
+		echo "100755 $(git hash-object -w stage2) 2	file"
+	) | git update-index --index-info &&
+	git config core.filemode 0 &&
+	echo new > file &&
+	git add file &&
+	git ls-files --stage | grep "^100755 .* 0	file$"
+'
+
 test_done