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From: "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: "Jeff King" <peff@peff.net>, "René Scharfe" <l.s.r@web.de>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Elijah Newren" <newren@gmail.com>,
	"Glen Choo" <chooglen@google.com>,
	"Philip Oakley" <philipoakley@iee.email>,
	"Elijah Newren" <newren@gmail.com>,
	"Elijah Newren" <newren@gmail.com>
Subject: [PATCH v3 09/11] dir: avoid incidentally removing the original_cwd in remove_path()
Date: Fri, 26 Nov 2021 22:41:00 +0000	[thread overview]
Message-ID: <2c73a09a2e83f08bcb0a5449f48e7e2ca5ac914e.1637966463.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.1140.v3.git.git.1637966463.gitgitgadget@gmail.com>

From: Elijah Newren <newren@gmail.com>

Modern git often tries to avoid leaving empty directories around when
removing files.  Originally, it did not bother.  This behavior started
with commit 80e21a9ed809 (merge-recursive::removeFile: remove empty
directories, 2005-11-19), stating the reason simply as:

    When the last file in a directory is removed as the result of a
    merge, try to rmdir the now-empty directory.

This was reimplemented in C and renamed to remove_path() in commit
e1b3a2cad7 ("Build-in merge-recursive", 2008-02-07), but was still
internal to merge-recursive.

This trend towards removing leading empty directories continued with
commit d9b814cc97f1 (Add builtin "git rm" command, 2006-05-19), which
stated the reasoning as:

    The other question is what to do with leading directories. The old
    "git rm" script didn't do anything, which is somewhat inconsistent.
    This one will actually clean up directories that have become empty
    as a result of removing the last file, but maybe we want to have a
    flag to decide the behaviour?

remove_path() in dir.c was added in 4a92d1bfb784 (Add remove_path: a
function to remove as much as possible of a path, 2008-09-27), because
it was noted that we had two separate implementations of the same idea
AND both were buggy.  It described the purpose of the function as

    a function to remove as much as possible of a path

Why remove as much as possible?  Well, at the time we probably would
have said something like:

  * removing leading directories makes things feel tidy
  * removing leading directories doesn't hurt anything so long as they
    had no files in them.

But I don't believe those reasons hold when the empty directory happens
to be the current working directory we inherited from our parent
process.  Leaving the parent process in a deleted directory can cause
user confusion when subsequent processes fail: any git command, for
example, will immediately fail with

    fatal: Unable to read current working directory: No such file or directory

Other commands may similarly get confused.  Modify remove_path() so that
the empty leading directories it also deletes does not include the
current working directory we inherited from our parent process.  I have
looked through every caller of remove_path() in the current codebase to
make sure that all should take this change.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 dir.c                |  3 +++
 dir.h                |  6 +++++-
 t/t2501-cwd-empty.sh | 12 ++++--------
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/dir.c b/dir.c
index 94489298f4c..97d6b71c872 100644
--- a/dir.c
+++ b/dir.c
@@ -3327,6 +3327,9 @@ int remove_path(const char *name)
 		slash = dirs + (slash - name);
 		do {
 			*slash = '\0';
+			if (startup_info->original_cwd &&
+			    !strcmp(startup_info->original_cwd, dirs))
+				break;
 		} while (rmdir(dirs) == 0 && (slash = strrchr(dirs, '/')));
 		free(dirs);
 	}
diff --git a/dir.h b/dir.h
index 83f46c0fb4c..d6a5d03bec2 100644
--- a/dir.h
+++ b/dir.h
@@ -504,7 +504,11 @@ int get_sparse_checkout_patterns(struct pattern_list *pl);
  */
 int remove_dir_recursively(struct strbuf *path, int flag);
 
-/* tries to remove the path with empty directories along it, ignores ENOENT */
+/*
+ * Tries to remove the path, along with leading empty directories so long as
+ * those empty directories are not startup_info->original_cwd.  Ignores
+ * ENOENT.
+ */
 int remove_path(const char *path);
 
 int fspathcmp(const char *a, const char *b);
diff --git a/t/t2501-cwd-empty.sh b/t/t2501-cwd-empty.sh
index 6788a0d267f..cba817ff734 100755
--- a/t/t2501-cwd-empty.sh
+++ b/t/t2501-cwd-empty.sh
@@ -175,12 +175,12 @@ test_expect_success 'revert fails if cwd needs to be removed' '
 '
 
 test_expect_success 'rm does not clean cwd incidentally' '
-	test_incidental_dir_removal failure git rm bar/baz.t
+	test_incidental_dir_removal success git rm bar/baz.t
 '
 
 test_expect_success 'apply does not remove cwd incidentally' '
 	git diff HEAD HEAD~1 >patch &&
-	test_incidental_dir_removal failure git apply ../patch
+	test_incidental_dir_removal success git apply ../patch
 '
 
 test_incidental_untracked_dir_removal () {
@@ -262,12 +262,8 @@ test_expect_success '`rm -rf dir` even with only tracked files will remove somet
 	) &&
 
 	test_path_is_missing a/b/c/tracked &&
-	## We would prefer if a/b was still present, though empty, since it
-	## was the current working directory
-	#test_path_is_dir a/b
-	## But the current behavior is that it not only deletes the directory
-	## a/b as requested, but also goes and deletes a
-	test_path_is_missing a
+	test_path_is_missing a/b/c &&
+	test_path_is_dir a/b
 '
 
 test_expect_success 'git version continues working from a deleted dir' '
-- 
gitgitgadget


  parent reply	other threads:[~2021-11-26 22:45 UTC|newest]

Thread overview: 163+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-21  0:46 [PATCH 0/8] Avoid removing the current working directory, even if it becomes empty Elijah Newren via GitGitGadget
2021-11-21  0:46 ` [PATCH 1/8] t2501: add various tests for removing the current working directory Elijah Newren via GitGitGadget
2021-11-21 17:57   ` Ævar Arnfjörð Bjarmason
2021-11-23  1:45     ` Elijah Newren
2021-11-23  2:19       ` Ævar Arnfjörð Bjarmason
2021-11-23  3:11         ` Elijah Newren
2021-11-25 10:04           ` Ævar Arnfjörð Bjarmason
2021-11-21  0:46 ` [PATCH 2/8] repository, setup: introduce the_cwd Elijah Newren via GitGitGadget
2021-11-21  8:00   ` Junio C Hamano
2021-11-22 22:38     ` Elijah Newren
2021-11-21  8:56   ` René Scharfe
2021-11-22 23:09     ` Elijah Newren
2021-11-21  0:46 ` [PATCH 3/8] unpack-trees: refuse to remove the current working directory Elijah Newren via GitGitGadget
2021-11-21  0:46 ` [PATCH 4/8] unpack-trees: add special cwd handling Elijah Newren via GitGitGadget
2021-11-21  0:46 ` [PATCH 5/8] symlinks: do not include current working directory in dir removal Elijah Newren via GitGitGadget
2021-11-21  8:56   ` René Scharfe
2021-11-23  0:35     ` Elijah Newren
2021-11-21  0:46 ` [PATCH 6/8] clean: do not attempt to remove current working directory Elijah Newren via GitGitGadget
2021-11-21 17:51   ` Ævar Arnfjörð Bjarmason
2021-11-23  1:28     ` Elijah Newren
2021-11-21  0:46 ` [PATCH 7/8] stash: " Elijah Newren via GitGitGadget
2021-11-21  0:47 ` [PATCH 8/8] dir: avoid removing the " Elijah Newren via GitGitGadget
2021-11-23  0:39   ` Glen Choo
2021-11-23  1:19     ` Elijah Newren
2021-11-23 18:19       ` Glen Choo
2021-11-23 19:56         ` Elijah Newren
2021-11-23 20:32           ` Glen Choo
2021-11-23 21:57             ` Junio C Hamano
2021-11-23 23:23               ` Elijah Newren
2021-11-24  5:46                 ` Junio C Hamano
2021-11-23 23:13             ` Elijah Newren
2021-11-24  0:39               ` Glen Choo
2021-11-24  5:46                 ` Junio C Hamano
2021-11-24  1:10           ` Ævar Arnfjörð Bjarmason
2021-11-24  4:35             ` Elijah Newren
2021-11-24 11:14               ` Ævar Arnfjörð Bjarmason
2021-11-24 14:11                 ` Ævar Arnfjörð Bjarmason
2021-11-25  2:54                   ` Elijah Newren
2021-11-25 11:12                     ` Ævar Arnfjörð Bjarmason
2021-11-26 21:40                       ` The overhead of bin-wrappers/ (was: [PATCH 8/8] dir: avoid removing the current working directory) Ævar Arnfjörð Bjarmason
2021-11-24 14:33                 ` [PATCH 8/8] dir: avoid removing the current working directory Philip Oakley
2021-11-24 19:46                   ` Junio C Hamano
2021-11-25 12:54                     ` Philip Oakley
2021-11-25 13:51                       ` Ævar Arnfjörð Bjarmason
2021-11-25  2:48                 ` Elijah Newren
2021-11-24 19:43               ` Junio C Hamano
2021-11-21  8:11 ` [PATCH 0/8] Avoid removing the current working directory, even if it becomes empty Junio C Hamano
2021-11-25  8:39 ` [PATCH v2 0/9] " Elijah Newren via GitGitGadget
2021-11-25  8:39   ` [PATCH v2 1/9] t2501: add various tests for removing the current working directory Elijah Newren via GitGitGadget
2021-11-25 10:21     ` Ævar Arnfjörð Bjarmason
2021-11-25  8:39   ` [PATCH v2 2/9] setup: introduce startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-25 10:44     ` Ævar Arnfjörð Bjarmason
2021-11-26 17:55       ` Elijah Newren
2021-11-26  6:52     ` Junio C Hamano
2021-11-26 18:01       ` Elijah Newren
2021-11-29 14:05     ` Derrick Stolee
2021-11-29 17:18       ` Elijah Newren
2021-11-29 17:43         ` Derrick Stolee
2021-11-29 17:42       ` Junio C Hamano
2021-11-25  8:39   ` [PATCH v2 3/9] unpack-trees: refuse to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-25 10:56     ` Ævar Arnfjörð Bjarmason
2021-11-26 18:06       ` Elijah Newren
2021-11-29 14:10     ` Derrick Stolee
2021-11-29 17:26       ` Elijah Newren
2021-11-25  8:39   ` [PATCH v2 4/9] unpack-trees: add special cwd handling Elijah Newren via GitGitGadget
2021-11-29 14:14     ` Derrick Stolee
2021-11-29 17:33       ` Elijah Newren
2021-11-25  8:39   ` [PATCH v2 5/9] symlinks: do not include startup_info->original_cwd in dir removal Elijah Newren via GitGitGadget
2021-11-25  8:39   ` [PATCH v2 6/9] clean: do not attempt to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-25  8:39   ` [PATCH v2 7/9] stash: " Elijah Newren via GitGitGadget
2021-11-25 10:58     ` Ævar Arnfjörð Bjarmason
2021-11-26 18:04       ` Elijah Newren
2021-11-25  8:39   ` [PATCH v2 8/9] dir: avoid incidentally removing the original_cwd in remove_path() Elijah Newren via GitGitGadget
2021-11-25  8:39   ` [PATCH v2 9/9] dir: new flag to remove_dir_recurse() to spare the original_cwd Elijah Newren via GitGitGadget
2021-11-26 22:40   ` [PATCH v3 00/11] Avoid removing the current working directory, even if it becomes empty Elijah Newren via GitGitGadget
2021-11-26 22:40     ` [PATCH v3 01/11] t2501: add various tests for removing the current working directory Elijah Newren via GitGitGadget
2021-11-27 10:32       ` Ævar Arnfjörð Bjarmason
2021-11-27 19:16         ` Elijah Newren
2021-11-26 22:40     ` [PATCH v3 02/11] setup: introduce startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-27 10:35       ` Ævar Arnfjörð Bjarmason
2021-11-27 17:05         ` Elijah Newren
2021-11-27 10:40       ` Ævar Arnfjörð Bjarmason
2021-11-27 18:31         ` Elijah Newren
2021-11-28 18:04           ` Ævar Arnfjörð Bjarmason
2021-11-29 21:58             ` Elijah Newren
2021-11-26 22:40     ` [PATCH v3 03/11] unpack-trees: refuse to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-26 22:40     ` [PATCH v3 04/11] unpack-trees: add special cwd handling Elijah Newren via GitGitGadget
2021-11-26 22:40     ` [PATCH v3 05/11] symlinks: do not include startup_info->original_cwd in dir removal Elijah Newren via GitGitGadget
2021-11-26 22:40     ` [PATCH v3 06/11] clean: do not attempt to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-26 22:40     ` [PATCH v3 07/11] rebase: " Elijah Newren via GitGitGadget
2021-11-29 17:50       ` Derrick Stolee
2021-11-29 19:22         ` Elijah Newren
2021-11-29 19:42           ` Derrick Stolee
2021-11-26 22:40     ` [PATCH v3 08/11] stash: " Elijah Newren via GitGitGadget
2021-11-26 22:41     ` Elijah Newren via GitGitGadget [this message]
2021-11-26 22:41     ` [PATCH v3 10/11] dir: new flag to remove_dir_recurse() to spare the original_cwd Elijah Newren via GitGitGadget
2021-11-26 22:41     ` [PATCH v3 11/11] t2501: simplify the tests since we can now assume desired behavior Elijah Newren via GitGitGadget
2021-11-29 17:57     ` [PATCH v3 00/11] Avoid removing the current working directory, even if it becomes empty Derrick Stolee
2021-11-29 22:37     ` [PATCH v4 " Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 01/11] t2501: add various tests for removing the current working directory Elijah Newren via GitGitGadget
2021-11-30  6:47         ` Junio C Hamano
2021-11-30  6:53           ` Elijah Newren
2021-11-29 22:37       ` [PATCH v4 02/11] setup: introduce startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 03/11] unpack-trees: refuse to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 04/11] unpack-trees: add special cwd handling Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 05/11] symlinks: do not include startup_info->original_cwd in dir removal Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 06/11] clean: do not attempt to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 07/11] rebase: " Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 08/11] stash: " Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 09/11] dir: avoid incidentally removing the original_cwd in remove_path() Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 10/11] dir: new flag to remove_dir_recurse() to spare the original_cwd Elijah Newren via GitGitGadget
2021-11-29 22:37       ` [PATCH v4 11/11] t2501: simplify the tests since we can now assume desired behavior Elijah Newren via GitGitGadget
2021-11-29 23:38       ` [PATCH v4 00/11] Avoid removing the current working directory, even if it becomes empty Eric Sunshine
2021-11-30  0:16         ` Elijah Newren
2021-12-01  6:40       ` [PATCH v5 " Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 01/11] t2501: add various tests for removing the current working directory Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 02/11] setup: introduce startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 03/11] unpack-trees: refuse to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 04/11] unpack-trees: add special cwd handling Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 05/11] symlinks: do not include startup_info->original_cwd in dir removal Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 06/11] clean: do not attempt to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 07/11] rebase: " Elijah Newren via GitGitGadget
2022-01-25 20:26           ` [Bug] Rebase from worktree subdir is broken (was Re: [PATCH v5 07/11] rebase: do not attempt to remove startup_info->original_cwd) Glen Choo
2022-01-25 23:59             ` Elijah Newren
2022-01-26  0:30               ` Glen Choo
2022-01-26 19:04                 ` Elijah Newren
2022-01-26  0:32               ` Eric Sunshine
2022-01-26  0:38                 ` Eric Sunshine
2022-01-26  0:51                   ` Elijah Newren
2022-01-26  1:15                     ` Glen Choo
2022-01-26  1:38                       ` Elijah Newren
2022-01-26 11:00               ` Phillip Wood
2022-01-26 17:53                 ` Eric Sunshine
2022-01-27 11:01                   ` Phillip Wood
2022-01-27 20:03                   ` Elijah Newren
2022-02-05 11:23                     ` Eric Sunshine
2022-02-05 11:42                       ` Eric Sunshine
2022-02-05 22:35                         ` Elijah Newren
2021-12-01  6:40         ` [PATCH v5 08/11] stash: do not attempt to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 09/11] dir: avoid incidentally removing the original_cwd in remove_path() Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 10/11] dir: new flag to remove_dir_recurse() to spare the original_cwd Elijah Newren via GitGitGadget
2021-12-01  6:40         ` [PATCH v5 11/11] t2501: simplify the tests since we can now assume desired behavior Elijah Newren via GitGitGadget
2021-12-07 16:09         ` [PATCH v5 00/11] Avoid removing the current working directory, even if it becomes empty Derrick Stolee
2021-12-07 18:30           ` Ævar Arnfjörð Bjarmason
2021-12-07 20:57             ` Derrick Stolee
2021-12-08 10:23               ` Ævar Arnfjörð Bjarmason
2021-12-07 20:43           ` Elijah Newren
2021-12-07 21:00             ` Derrick Stolee
2021-12-09  5:08         ` [PATCH v6 " Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 01/11] t2501: add various tests for removing the current working directory Elijah Newren via GitGitGadget
2022-03-11 11:57             ` Ævar Arnfjörð Bjarmason
2021-12-09  5:08           ` [PATCH v6 02/11] setup: introduce startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 03/11] unpack-trees: refuse to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 04/11] unpack-trees: add special cwd handling Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 05/11] symlinks: do not include startup_info->original_cwd in dir removal Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 06/11] clean: do not attempt to remove startup_info->original_cwd Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 07/11] rebase: " Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 08/11] stash: " Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 09/11] dir: avoid incidentally removing the original_cwd in remove_path() Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 10/11] dir: new flag to remove_dir_recurse() to spare the original_cwd Elijah Newren via GitGitGadget
2021-12-09  5:08           ` [PATCH v6 11/11] t2501: simplify the tests since we can now assume desired behavior Elijah Newren via GitGitGadget
2021-11-30 11:04     ` [PATCH v3 00/11] Avoid removing the current working directory, even if it becomes empty Phillip Wood
2021-12-01  0:03       ` Elijah Newren

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