On Thu, Jan 23, 2014 at 11:45:25AM +0900, IWAMOTO Toshihiro wrote:
I found git-diff --quiet returns a zero exit status even if there's
a change. The following sequence reproduces the bug:
$ mkdir foo
$ cd foo
$ git init
$ echo a a.txt
$ echo b b.txt
$ git add ?.txt
$ git commit
$ echo b b.txt
$ touch a.txt
$ git diff --quiet; echo $?
Interestingly, if you issue git-diff --quiet again, it returns the
expected exit status 1.
Because stat info in index is updated and diff_change() won't be
called again on a.txt.
The problem is in the optimization code in run_diff_files(). The
function finds a.txt has different stat(2) data from .git/index and
calls diff_change(), which sets DIFF_OPT_HAS_CHANGES. As the flag
makes diff_can_quit_early() return 1, run_diff_files()'s loop finishes
without calling diff_change() for b.txt.
Then, diffcore_std() examines diff_queued_diff and clears
DIFF_OPT_HAS_CHANGES, because a.txt is unchanged.
This is how a change in b.txt is ignored by git-diff --quiet.
Thanks for the analysis. Perhaps we could make diff_change test
whether a.txt is unchanged so it does not set HAS_CHANGES prematurely?
Maybe something like below.
By the time diffcore_skip_stat_unmatch() is called, everything is
cached, so there's not much of performance regression. We still do
memcmp() twice (in diff_filespec_is_identical), but I think that has
less impact than removing diff_can_quit_early().
-- 8 --
diff --git a/diff.c b/diff.c
index 6b4cd0e..5226fc0 100644
--- a/diff.c
+++ b/diff.c
@@ -4697,6 +4697,33 @@ static int diff_filespec_is_identical(struct
diff_filespec *one,
return !memcmp(one-data, two-data, one-size);
}
+static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
+{
+ /*
+* 1. Entries that come from stat info dirtiness
+*always have both sides (iow, not create/delete),
+*one side of the object name is unknown, with
+*the same mode and size. Keep the ones that
+*do not match these criteria. They have real
+*differences.
+*
+* 2. At this point, the file is known to be modified,
+*with the same mode and size, and the object
+*name of one side is unknown. Need to inspect
+*the identical contents.
+*/
+ if (!DIFF_FILE_VALID(p-one) || /* (1) */
+ !DIFF_FILE_VALID(p-two) ||
+ (p-one-sha1_valid p-two-sha1_valid) ||
+ (p-one-mode != p-two-mode) ||
+ diff_populate_filespec(p-one, 1) ||
+ diff_populate_filespec(p-two, 1) ||
+ (p-one-size != p-two-size) ||
+ !diff_filespec_is_identical(p-one, p-two)) /* (2) */
+ return 1;
+ return 0;
+}
+
static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
{
int i;
@@ -4707,27 +4734,7 @@ static void diffcore_skip_stat_unmatch(struct
diff_options *diffopt)
for (i = 0; i q-nr; i++) {
struct diff_filepair *p = q-queue[i];
- /*
-* 1. Entries that come from stat info dirtiness
-*always have both sides (iow, not create/delete),
-*one side of the object name is unknown, with
-*the same mode and size. Keep the ones that
-*do not match these criteria. They have real
-*differences.
-*
-* 2. At this point, the file is known to be modified,
-*with the same mode and size, and the object
-*name of one side is unknown. Need to inspect
-*the identical contents.
-*/
- if (!DIFF_FILE_VALID(p-one) || /* (1) */
- !DIFF_FILE_VALID(p-two) ||
- (p-one-sha1_valid p-two-sha1_valid) ||
- (p-one-mode != p-two-mode) ||
- diff_populate_filespec(p-one, 1) ||
- diff_populate_filespec(p-two, 1) ||
- (p-one-size != p-two-size) ||
- !diff_filespec_is_identical(p-one, p-two)) /* (2) */
+ if (diff_filespec_check_stat_unmatch(p))
diff_q(outq, p);
else {
/*
@@ -4890,6 +4897,7 @@ void diff_change(struct diff_options *options,
unsigned old_dirty_submodule, unsigned new_dirty_submodule)
{
struct diff_filespec *one, *two;
+ struct diff_filepair *p;
if (S_ISGITLINK(old_mode) S_ISGITLINK(new_mode)
is_submodule_ignored(concatpath, options))
@@ -4916,10 +4924,17 @@ void diff_change(struct diff_options *options,
fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
one-dirty_submodule = old_dirty_submodule;
two-dirty_submodule = new_dirty_submodule;
+ p = diff_queue(diff_queued_diff, one, two);
-
