Fix D/F issues in stash

This series fixes a few D/F issues in the stash command. These were some issues I found while working on unintentional removal of untracked files/directories and the current working directory, and I'm just submitting them separately.

Elijah Newren (3):
t3903: document a pair of directory/file bugs
stash: avoid feeding directories to update-index
stash: restore untracked files AFTER restoring tracked files

 builtin/stash.c  | 15 ++++++++++++---
 t/t3903-stash.sh | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 3 deletions(-)

base-commit: e0a2f5cbc585657e757385ad918f167f519cfb96
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1086%2Fnewren%2Fstash-df-fixes-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1086/newren/stash-df-fixes-v1
Pull-Request: https://github.com/git/git/pull/1086

gitgitgadget

From: Elijah Newren <[email protected]>

---
 t/t3903-stash.sh | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

index 873aa56e359..0727a494aa4 100755
@@ -1307,4 +1307,42 @@ test_expect_success 'stash -c stash.useBuiltin=false warning ' '
 	test_must_be_empty err
 '
 
+test_expect_failure 'git stash succeeds despite directory/file change' '
+	test_create_repo directory_file_switch_v1 &&
+	(
+		cd directory_file_switch_v1 &&
+		test_commit init &&
+
+		test_write_lines this file has some words >filler &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm filler &&
+		mkdir filler &&
+		echo contents >filler/file &&
+		cp filler/file expect &&
+		git stash push
+	)
+'
+
+test_expect_failure 'git stash can pop directory/file saved changes' '
+	test_create_repo directory_file_switch_v2 &&
+	(
+		cd directory_file_switch_v2 &&
+		test_commit init &&
+
+		test_write_lines this file has some words >filler &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm filler &&
+		mkdir filler &&
+		echo contents >filler/file &&
+		cp filler/file expect &&
+		git stash push --include-untracked &&
+		git stash apply --index &&
+		test_cmp expect filler/file
+	)
+'
+
 test_done

gitgitgadget

From: Elijah Newren <[email protected]>

When a file is removed from the cache, but there is a file of the same name present in the working directory, we would normally treat that file in the working directory as untracked. However, in the case of stash, doing that would prevent a simple 'git stash push', because the untracked file would be in the way of restoring the deleted file.

git stash, however, blindly assumes that whatever is in the working directory for a deleted file is wanted and passes that path along to update-index. That causes problems when the working directory contains a directory with the same name as the deleted file. Add some code for this special case that will avoid passing directory names to update-index.

---
 builtin/stash.c  | 9 +++++++++
 t/t3903-stash.sh | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

index 8f42360ca91..b85cf9d267e 100644
@@ -313,6 +313,12 @@ static int reset_head(void)
 	return run_command(&cp);
 }
 
+static int is_path_a_directory(const char *path)
+{
+	struct stat st;
+	return (!lstat(path, &st) && S_ISDIR(st.st_mode));
+}
+
 static void add_diff_to_buf(struct diff_queue_struct *q,
 			    struct diff_options *options,
 			    void *data)

@@ -320,6 +326,9 @@ static void add_diff_to_buf(struct diff_queue_struct *q,
 	int i;
 
 	for (i = 0; i < q->nr; i++) {
+		if (is_path_a_directory(q->queue[i]->one->path))
+			continue;
+
 		strbuf_addstr(data, q->queue[i]->one->path);
 
 		/* NUL-terminate: will be fed to update-index -z */

index 0727a494aa4..fc74918ccc0 100755
@@ -1307,7 +1307,7 @@ test_expect_success 'stash -c stash.useBuiltin=false warning ' '
 	test_must_be_empty err
 '
 
-test_expect_failure 'git stash succeeds despite directory/file change' '
+test_expect_success 'git stash succeeds despite directory/file change' '
 	test_create_repo directory_file_switch_v1 &&
 	(
 		cd directory_file_switch_v1 &&

gitgitgadget

From: Elijah Newren <[email protected]>

If a user deletes a file and places a directory of untracked files there, then stashes all these changes, the untracked directory of files cannot be restored until after the corresponding file in the way is removed. So, restore changes to tracked files before restoring untracked files.

There is no similar problem to worry about in the opposite directory, because untracked files are always additive. Said another way, there's no way to "stash a removal of an untracked file" because if an untracked file is removed, git simply doesn't know about it.

---
 builtin/stash.c  | 6 +++---
 t/t3903-stash.sh | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

index b85cf9d267e..9a1f6a5a854 100644
@@ -530,9 +530,6 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 		}
 	}
 
-	if (info->has_u && restore_untracked(&info->u_tree))
-		return error(_("could not restore untracked files from stash"));
-
 	init_merge_options(&o, the_repository);
 
 	o.branch1 = "Updated upstream";

@@ -567,6 +564,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 		unstage_changes_unless_new(&c_tree);
 	}
 
+	if (info->has_u && restore_untracked(&info->u_tree))
+		return error(_("could not restore untracked files from stash"));
+
 	if (!quiet) {
 		struct child_process cp = CHILD_PROCESS_INIT;
 

index fc74918ccc0..bfd3158a502 100755
@@ -1325,7 +1325,7 @@ test_expect_success 'git stash succeeds despite directory/file change' '
 	)
 '
 
-test_expect_failure 'git stash can pop directory/file saved changes' '
+test_expect_success 'git stash can pop directory/file saved changes' '
 	test_create_repo directory_file_switch_v2 &&
 	(
 		cd directory_file_switch_v2 &&

gitgitgadget

Hi Elijah,

	/*
	 * Do not use this for inspecting *tracked* content.  When path is a
	 * symlink to a directory, we do not want to say it is a directory when
	 * dealing with tracked content in the working tree.
	 */
	int is_directory(const char *path)
	{
		struct stat st;
		return (!stat(path, &st) && S_ISDIR(st.st_mode));
	}

Hi Elijah,

Awesome work! Apart from asking for an additional clarification in the commit message of the second patch, I have nothing else to offer but my sincere thanks for working on the stash code.

Thank you,
Dscho

s/directory/direction/ ?

Makes sense.

Thanks,
-Stolee

I found what is probably a typo in a commit message, but otherwise this looks great.

Thanks,
-Stolee

direction, I think.

If a user deletes a directory with tracked files in it and places an untracked file at the path the directory used to be, and then stash all these changes, that would be the opposite direction, I would presume? The untracked file would be restorable only after applying the removal of the tracked files that occupied the directory.

Which would be fine if we apply the changes to the tracked ones first.

OK.

After creating a stash, we clear the working tree. How do we do that exactly, and would we have a similar problem there? We need to first remove the untracked file that currently occupies where the directory used to be in HEAD, and then create the directory and resurrect the tracked files in the directory from HEAD, in my modified example above. In the file-becomes-directory scenario, is the story the same?

Thanks.

This series fixes a few D/F issues in the stash command. These were some issues I found while working on unintentional removal of untracked files/directories and the current working directory, and I'm just submitting them separately.

Changes since v1:

* Fix accidental creation of file named 'expect' (copy-paste problem...)
* Documented the reason for adding is_path_a_directory() and not using is_directory()
* Removed typo, fixed up confusing wording, and added a companion test to show that F->D and D->F have the same fix.

Elijah Newren (3):
t3903: document a pair of directory/file bugs
stash: avoid feeding directories to update-index
stash: restore untracked files AFTER restoring tracked files

 builtin/stash.c  | 20 ++++++++++++++---
 t/t3903-stash.sh | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+), 3 deletions(-)

base-commit: e0a2f5cbc585657e757385ad918f167f519cfb96
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1086%2Fnewren%2Fstash-df-fixes-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1086/newren/stash-df-fixes-v2
Pull-Request: https://github.com/git/git/pull/1086

Range-diff vs v1:

1: bc66a6ae75d ! 1: 5ddb70d332b t3903: document a pair of directory/file bugs

     @@ Metadata
       ## Commit message ##
          t3903: document a pair of directory/file bugs
      
     +    There are three tests here, because the second bug is documented with
     +    two tests: a file -> directory change and a directory -> file change.
     +    The reason for the two tests is just to verify that both are indeed
     +    broken but that both will be fixed by the same simple change (which will
     +    be provided in a subsequent patch).
     +
          Signed-off-by: Elijah Newren <[email protected]>
      
       ## t/t3903-stash.sh ##
     @@ t/t3903-stash.sh: test_expect_success 'stash -c stash.useBuiltin=false warning '
      +		git rm filler &&
      +		mkdir filler &&
      +		echo contents >filler/file &&
     -+		cp filler/file expect &&
      +		git stash push
      +	)
      +'
      +
     -+test_expect_failure 'git stash can pop directory/file saved changes' '
     ++test_expect_failure 'git stash can pop file -> directory saved changes' '
      +	test_create_repo directory_file_switch_v2 &&
      +	(
      +		cd directory_file_switch_v2 &&
     @@ t/t3903-stash.sh: test_expect_success 'stash -c stash.useBuiltin=false warning '
      +		test_cmp expect filler/file
      +	)
      +'
     ++
     ++test_expect_failure 'git stash can pop directory -> file saved changes' '
     ++	test_create_repo directory_file_switch_v3 &&
     ++	(
     ++		cd directory_file_switch_v3 &&
     ++		test_commit init &&
     ++
     ++		mkdir filler &&
     ++		test_write_lines some words >filler/file1 &&
     ++		test_write_lines and stuff >filler/file2 &&
     ++		git add filler &&
     ++		git commit -m filler &&
     ++
     ++		git rm -rf filler &&
     ++		echo contents >filler &&
     ++		cp filler expect &&
     ++		git stash push --include-untracked &&
     ++		git stash apply --index &&
     ++		test_cmp expect filler
     ++	)
     ++'
      +
       test_done
 2:  c7f5ae66a92 ! 2:  31e38c6c33c stash: avoid feeding directories to update-index
     @@ builtin/stash.c: static int reset_head(void)
       
      +static int is_path_a_directory(const char *path)
      +{
     ++	/*
     ++	 * This function differs from abspath.c:is_directory() in that
     ++	 * here we use lstat() instead of stat(); we do not want to
     ++	 * follow symbolic links here.
     ++	 */
      +	struct stat st;
      +	return (!lstat(path, &st) && S_ISDIR(st.st_mode));
      +}

3: ac8ca07481d ! 3: 6254938948c stash: restore untracked files AFTER restoring tracked files
@@ Commit message
removed. So, restore changes to tracked files before restoring untracked files.

- There is no similar problem to worry about in the opposite directory,
- because untracked files are always additive. Said another way, there's
- no way to "stash a removal of an untracked file" because if an untracked
- file is removed, git simply doesn't know about it.
+ There is no counterpart problem to worry about with the user deleting an
+ untracked file and then add a tracked one in its place. Git does not
+ track untracked files, and so will not know the untracked file was
+ deleted, and thus won't be able to stash the removal of that file.

@@ t/t3903-stash.sh: test_expect_success 'git stash succeeds despite directory/file
)
'

--test_expect_failure 'git stash can pop directory/file saved changes' ' -+test_expect_success 'git stash can pop directory/file saved changes' ' +-test_expect_failure 'git stash can pop file -> directory saved changes' ' ++test_expect_success 'git stash can pop file -> directory saved changes' '
test_create_repo directory_file_switch_v2 &&
(
cd directory_file_switch_v2 &&
+@@ t/t3903-stash.sh: test_expect_failure 'git stash can pop file -> directory saved changes' '
+ )
+ '
+
+-test_expect_failure 'git stash can pop directory -> file saved changes' ' ++test_expect_success 'git stash can pop directory -> file saved changes' '
+ test_create_repo directory_file_switch_v3 &&
+ (
+ cd directory_file_switch_v3 &&

gitgitgadget

From: Elijah Newren <[email protected]>

There are three tests here, because the second bug is documented with two tests: a file -> directory change and a directory -> file change. The reason for the two tests is just to verify that both are indeed broken but that both will be fixed by the same simple change (which will be provided in a subsequent patch).

---
 t/t3903-stash.sh | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

index 873aa56e359..7346f8d1037 100755
@@ -1307,4 +1307,62 @@ test_expect_success 'stash -c stash.useBuiltin=false warning ' '
 	test_must_be_empty err
 '
 
+test_expect_failure 'git stash succeeds despite directory/file change' '
+	test_create_repo directory_file_switch_v1 &&
+	(
+		cd directory_file_switch_v1 &&
+		test_commit init &&
+
+		test_write_lines this file has some words >filler &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm filler &&
+		mkdir filler &&
+		echo contents >filler/file &&
+		git stash push
+	)
+'
+
+test_expect_failure 'git stash can pop file -> directory saved changes' '
+	test_create_repo directory_file_switch_v2 &&
+	(
+		cd directory_file_switch_v2 &&
+		test_commit init &&
+
+		test_write_lines this file has some words >filler &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm filler &&
+		mkdir filler &&
+		echo contents >filler/file &&
+		cp filler/file expect &&
+		git stash push --include-untracked &&
+		git stash apply --index &&
+		test_cmp expect filler/file
+	)
+'
+
+test_expect_failure 'git stash can pop directory -> file saved changes' '
+	test_create_repo directory_file_switch_v3 &&
+	(
+		cd directory_file_switch_v3 &&
+		test_commit init &&
+
+		mkdir filler &&
+		test_write_lines some words >filler/file1 &&
+		test_write_lines and stuff >filler/file2 &&
+		git add filler &&
+		git commit -m filler &&
+
+		git rm -rf filler &&
+		echo contents >filler &&
+		cp filler expect &&
+		git stash push --include-untracked &&
+		git stash apply --index &&
+		test_cmp expect filler
+	)
+'
+
 test_done

gitgitgadget

From: Elijah Newren <[email protected]>

When a file is removed from the cache, but there is a file of the same name present in the working directory, we would normally treat that file in the working directory as untracked. However, in the case of stash, doing that would prevent a simple 'git stash push', because the untracked file would be in the way of restoring the deleted file.

git stash, however, blindly assumes that whatever is in the working directory for a deleted file is wanted and passes that path along to update-index. That causes problems when the working directory contains a directory with the same name as the deleted file. Add some code for this special case that will avoid passing directory names to update-index.

---
 builtin/stash.c  | 14 ++++++++++++++
 t/t3903-stash.sh |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

index 8f42360ca91..9ad2940f87a 100644
@@ -313,6 +313,17 @@ static int reset_head(void)
 	return run_command(&cp);
 }
 
+static int is_path_a_directory(const char *path)
+{
+	/*
+	 * This function differs from abspath.c:is_directory() in that
+	 * here we use lstat() instead of stat(); we do not want to
+	 * follow symbolic links here.
+	 */
+	struct stat st;
+	return (!lstat(path, &st) && S_ISDIR(st.st_mode));
+}
+
 static void add_diff_to_buf(struct diff_queue_struct *q,
 			    struct diff_options *options,
 			    void *data)

@@ -320,6 +331,9 @@ static void add_diff_to_buf(struct diff_queue_struct *q,
 	int i;
 
 	for (i = 0; i < q->nr; i++) {
+		if (is_path_a_directory(q->queue[i]->one->path))
+			continue;
+
 		strbuf_addstr(data, q->queue[i]->one->path);
 
 		/* NUL-terminate: will be fed to update-index -z */

index 7346f8d1037..34d1ad9837f 100755
@@ -1307,7 +1307,7 @@ test_expect_success 'stash -c stash.useBuiltin=false warning ' '
 	test_must_be_empty err
 '
 
-test_expect_failure 'git stash succeeds despite directory/file change' '
+test_expect_success 'git stash succeeds despite directory/file change' '
 	test_create_repo directory_file_switch_v1 &&
 	(
 		cd directory_file_switch_v1 &&

gitgitgadget

From: Elijah Newren <[email protected]>

If a user deletes a file and places a directory of untracked files there, then stashes all these changes, the untracked directory of files cannot be restored until after the corresponding file in the way is removed. So, restore changes to tracked files before restoring untracked files.

There is no counterpart problem to worry about with the user deleting an untracked file and then add a tracked one in its place. Git does not track untracked files, and so will not know the untracked file was deleted, and thus won't be able to stash the removal of that file.

---
 builtin/stash.c  | 6 +++---
 t/t3903-stash.sh | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

index 9ad2940f87a..5512f4942cd 100644
@@ -535,9 +535,6 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 		}
 	}
 
-	if (info->has_u && restore_untracked(&info->u_tree))
-		return error(_("could not restore untracked files from stash"));
-
 	init_merge_options(&o, the_repository);
 
 	o.branch1 = "Updated upstream";

@@ -572,6 +569,9 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 		unstage_changes_unless_new(&c_tree);
 	}
 
+	if (info->has_u && restore_untracked(&info->u_tree))
+		return error(_("could not restore untracked files from stash"));
+
 	if (!quiet) {
 		struct child_process cp = CHILD_PROCESS_INIT;
 

index 34d1ad9837f..f0a82be9de7 100755
@@ -1324,7 +1324,7 @@ test_expect_success 'git stash succeeds despite directory/file change' '
 	)
 '
 
-test_expect_failure 'git stash can pop file -> directory saved changes' '
+test_expect_success 'git stash can pop file -> directory saved changes' '
 	test_create_repo directory_file_switch_v2 &&
 	(
 		cd directory_file_switch_v2 &&

@@ -1344,7 +1344,7 @@ test_expect_failure 'git stash can pop file -> directory saved changes' '
 	)
 '
 
-test_expect_failure 'git stash can pop directory -> file saved changes' '
+test_expect_success 'git stash can pop directory -> file saved changes' '
 	test_create_repo directory_file_switch_v3 &&
 	(
 		cd directory_file_switch_v3 &&

gitgitgadget