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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>,
	"Derrick Stolee" <stolee@gmail.com>,
	"Elijah Newren" <newren@gmail.com>,
	"Elijah Newren" <newren@gmail.com>
Subject: [PATCH v4 02/11] setup: introduce startup_info->original_cwd
Date: Mon, 29 Nov 2021 22:37:05 +0000	[thread overview]
Message-ID: <ca9f632bd119d6aa507976e35dc0d1b178fdeea7.1638225434.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.1140.v4.git.git.1638225434.gitgitgadget@gmail.com>

From: Elijah Newren <newren@gmail.com>

Removing the current working directory causes all subsequent git
commands run from that directory to get confused and fail with a message
about being unable to read the current working directory:

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

Non-git commands likely have similar warnings or even errors, e.g.

    $ bash -c 'echo hello'
    shell-init: error retrieving current directory: getcwd: cannot access parent directories: No such file or directory
    hello

This confuses end users, particularly since the command they get the
error from is not the one that caused the problem; the problem came from
the side-effect of some previous command.

We would like to avoid removing the current working directory of our
parent process; towards this end, introduce a new variable,
startup_info->original_cwd, that tracks the current working directory
that we inherited from our parent process.  For convenience of later
comparisons, we prefer that this new variable store a path relative to
the toplevel working directory (thus much like 'prefix'), except without
the trailing slash.

Subsequent commits will make use of this new variable.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 cache.h       |  2 ++
 common-main.c |  4 ++++
 setup.c       | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/cache.h b/cache.h
index eba12487b99..92e181ea759 100644
--- a/cache.h
+++ b/cache.h
@@ -1834,8 +1834,10 @@ void overlay_tree_on_index(struct index_state *istate,
 struct startup_info {
 	int have_repository;
 	const char *prefix;
+	const char *original_cwd;
 };
 extern struct startup_info *startup_info;
+extern const char *tmp_original_cwd;
 
 /* merge.c */
 struct commit_list;
diff --git a/common-main.c b/common-main.c
index 71e21dd20a3..aa8d5aba5bb 100644
--- a/common-main.c
+++ b/common-main.c
@@ -26,6 +26,7 @@ static void restore_sigpipe_to_default(void)
 int main(int argc, const char **argv)
 {
 	int result;
+	struct strbuf tmp = STRBUF_INIT;
 
 	trace2_initialize_clock();
 
@@ -49,6 +50,9 @@ int main(int argc, const char **argv)
 	trace2_cmd_start(argv);
 	trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP);
 
+	if (!strbuf_getcwd(&tmp))
+		tmp_original_cwd = strbuf_detach(&tmp, NULL);
+
 	result = cmd_main(argc, argv);
 
 	trace2_cmd_exit(result);
diff --git a/setup.c b/setup.c
index 347d7181ae9..af3b8c09abe 100644
--- a/setup.c
+++ b/setup.c
@@ -12,6 +12,7 @@ static int work_tree_config_is_bogus;
 
 static struct startup_info the_startup_info;
 struct startup_info *startup_info = &the_startup_info;
+const char *tmp_original_cwd;
 
 /*
  * The input parameter must contain an absolute path, and it must already be
@@ -432,6 +433,69 @@ void setup_work_tree(void)
 	initialized = 1;
 }
 
+static void setup_original_cwd(void)
+{
+	struct strbuf tmp = STRBUF_INIT;
+	const char *worktree = NULL;
+	int offset = -1;
+
+	if (!tmp_original_cwd)
+		return;
+
+	/*
+	 * startup_info->original_cwd points to the current working
+	 * directory we inherited from our parent process, which is a
+	 * directory we want to avoid removing.
+	 *
+	 * For convience, we would like to have the path relative to the
+	 * worktree instead of an absolute path.
+	 *
+	 * Yes, startup_info->original_cwd is usually the same as 'prefix',
+	 * but differs in two ways:
+	 *   - prefix has a trailing '/'
+	 *   - if the user passes '-C' to git, that modifies the prefix but
+	 *     not startup_info->original_cwd.
+	 */
+
+	/* Normalize the directory */
+	strbuf_realpath(&tmp, tmp_original_cwd, 1);
+	free((char*)tmp_original_cwd);
+	tmp_original_cwd = NULL;
+	startup_info->original_cwd = strbuf_detach(&tmp, NULL);
+
+	/*
+	 * Get our worktree; we only protect the current working directory
+	 * if it's in the worktree.
+	 */
+	worktree = get_git_work_tree();
+	if (!worktree)
+		goto no_prevention_needed;
+
+	offset = dir_inside_of(startup_info->original_cwd, worktree);
+	if (offset >= 0) {
+		/*
+		 * If startup_info->original_cwd == worktree, that is already
+		 * protected and we don't need original_cwd as a secondary
+		 * protection measure.
+		 */
+		if (!*(startup_info->original_cwd + offset))
+			goto no_prevention_needed;
+
+		/*
+		 * original_cwd was inside worktree; precompose it just as
+		 * we do prefix so that built up paths will match
+		 */
+		startup_info->original_cwd = \
+			precompose_string_if_needed(startup_info->original_cwd
+						    + offset);
+		return;
+	}
+
+no_prevention_needed:
+	free((char*)startup_info->original_cwd);
+	startup_info->original_cwd = NULL;
+}
+
 static int read_worktree_config(const char *var, const char *value, void *vdata)
 {
 	struct repository_format *data = vdata;
@@ -1330,6 +1394,7 @@ const char *setup_git_directory_gently(int *nongit_ok)
 		setenv(GIT_PREFIX_ENVIRONMENT, "", 1);
 	}
 
+	setup_original_cwd();
 
 	strbuf_release(&dir);
 	strbuf_release(&gitdir);
-- 
gitgitgadget


  parent reply	other threads:[~2021-11-29 23:10 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     ` [PATCH v3 09/11] dir: avoid incidentally removing the original_cwd in remove_path() Elijah Newren via GitGitGadget
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       ` Elijah Newren via GitGitGadget [this message]
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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