git diff HEAD^(255) fails

git diff first looks for a file, then looks if it is a reference to a
revision. If the file fails due to being too long, the diff fails:

$ git init
$ git diff 'HEAD^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^'
HEAD
fatal: failed to stat
'HEAD^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^':
File name too long

If file name too long it should just try to see if it is a reference
to a revision.


/Ole

Noticed-by: Ole Tange [off-list ref]
Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 On Sun, Feb 7, 2016 at 4:56 AM, Ole Tange [off-list ref] wrote:
 > If file name too long it should just try to see if it is a reference
 > to a revision.

 Looks easy enough to fix.

 setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.c b/setup.c
index 2c4b22c..ab8f85d 100644
--- a/setup.c
+++ b/setup.c

@@ -147,7 +147,7 @@ int check_filename(const char *prefix, const char *arg)
 		name = arg;
 	if (!lstat(name, &st))
 		return 1; /* file exists */
-	if (errno == ENOENT || errno == ENOTDIR)
+	if (errno == ENOENT || errno == ENOTDIR || errno == ENAMETOOLONG)
 		return 0; /* file does not exist */
 	die_errno("failed to stat '%s'", arg);
 }

-- 
2.7.0.377.g4cd97dd

Hi Duy,

On Sun, 7 Feb 2016, Nguyễn Thái Ngọc Duy wrote:

Noticed-by: Ole Tange [off-list ref]
Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 On Sun, Feb 7, 2016 at 4:56 AM, Ole Tange [off-list ref] wrote:
 > If file name too long it should just try to see if it is a reference
 > to a revision.

 Looks easy enough to fix.

Maybe with a little bit more informative commit message? ;-)

Something like

	Avoid interpreting too-long parameter as file name

	Even if it is easier to write HEAD~2000, it is legal to write
	HEAD^^^... (repeats "^" 2000 times in total). However, such a
	string is too long to be a legal filename (and on Windows, by
	default even much, much shorter strings are still illegal
	because they exceed MAX_PATH).

	Therefore, if the check_filename() function encounters too long
	a command-line parameter, it should interpet the error code
	ENAMETOOLONG as a strong hint that this is not a file name
	instead of dying with an error message.

	Noticed-by: ...

What do you think?
Dscho

Even if it is easier to write HEAD~2000, it is legal to write
HEAD^^^... (repeats "^" 2000 times in total). However, such a string is
too long to be a legal filename (and on Windows, by default even much,
much shorter strings are still illegal because they exceed MAX_PATH).

Therefore, if the check_filename() function encounters too long a
command-line parameter, it should interpet the error code ENAMETOOLONG
as a strong hint that this is not a file name instead of dying with an
error message.

Noticed-by: Ole Tange [off-list ref]
Helped-by: Johannes Schindelin [off-list ref]
Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 Note, git grep ENOENT.*ENOTDIR reveals a couple more matches, but I
 didn't check if they should receive the same treatment.

 Another option is just use file_exists() here instead, but I guess
 that's too relaxing.

 setup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.c b/setup.c
index 2c4b22c..ab8f85d 100644
--- a/setup.c
+++ b/setup.c

@@ -147,7 +147,7 @@ int check_filename(const char *prefix, const char *arg)
 		name = arg;
 	if (!lstat(name, &st))
 		return 1; /* file exists */
-	if (errno == ENOENT || errno == ENOTDIR)
+	if (errno == ENOENT || errno == ENOTDIR || errno == ENAMETOOLONG)
 		return 0; /* file does not exist */
 	die_errno("failed to stat '%s'", arg);
 }

-- 
2.7.0.377.g4cd97dd

On Sat, Feb 06, 2016 at 10:56:46PM +0100, Ole Tange wrote:

git diff first looks for a file, then looks if it is a reference to a
revision. If the file fails due to being too long, the diff fails:

$ git init
$ git diff 'HEAD^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^'
HEAD
fatal: failed to stat
'HEAD^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^':
File name too long

If file name too long it should just try to see if it is a reference
to a revision.

Is there a reason you are repeating 255 "^" instead of using HEAD~255?