From: Junio C Hamano <gitster@pobox•com>
To: Abhijeet Sonar <abhijeet.nkt@gmail•com>
Cc: Karthik Nayak <karthik.188@gmail•com>,
git@vger•kernel.org, Paul Millar <paul.millar@desy•de>,
Phillip Wood <phillip.wood123@gmail•com>,
Elijah Newren <newren@gmail•com>, Jeff King <peff@peff•net>
Subject: Re: Re* [PATCH v5] describe: refresh the index when 'broken' flag is used
Date: Wed, 26 Jun 2024 09:17:37 -0700 [thread overview]
Message-ID: <xmqqcyo33cgu.fsf@gitster.g> (raw)
In-Reply-To: <xmqqikxv4t1v.fsf_-_@gitster.g> (Junio C. Hamano's message of "Wed, 26 Jun 2024 08:34:04 -0700")
Junio C Hamano <gitster@pobox•com> writes:
> Subject: [PATCH] fsck: clear child_process after failed run_command()
>
> There are two loops that calls run_command() using the same
> child_process struct near the end of cmd_fsck(). 4d0984be (fsck: do
> not reuse child_process structs, 2018-11-12) tightened these code
> paths to reinitialize the structure in order to safely reuse it.
>
> The run-command API makes no promises about what is left in a struct
> child_process after a command finishes, and it's not safe to simply
> reuse it again for a similar command.
>
> Upon failure, run_command() can return without releasing the
> resource held by the child_process structure, which is done by
> calling finish_command() which in turn calls child_process_clear().
Sorry, but I have to take this back.
The error return code paths in the start_command() function does
seem to call clear_child_process(), which means that there is no
need to call clear_child_process() ourselves after a failed
run_command() call.
The need for reinitializing that established by 4d0984be (fsck: do
not reuse child_process structs, 2018-11-12) still stand, so
... the first run ...
run_command(&cp);
/* no need for separate child_process_clear(&cp) */
child_process_init(&cp); /* prepare for reuse */
... setup for the second run ...
strvec_pushv(&cp.args, diff_index_args);
cp.git_cmd = 1;
... full set-up without relying on anything done earlier ...
would still be needed.
Or alternatively, we could do this to ensure that the child_process
structure is always reusable.
run-command.c | 1 +
run-command.h | 6 +++++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git c/run-command.c w/run-command.c
index 6ac1d14516..aba250fbe1 100644
--- c/run-command.c
+++ w/run-command.c
@@ -26,6 +26,7 @@ void child_process_clear(struct child_process *child)
{
strvec_clear(&child->args);
strvec_clear(&child->env);
+ child_process_init(child);
}
struct child_to_clean {
diff --git c/run-command.h w/run-command.h
index 55f6631a2a..6e203c22f6 100644
--- c/run-command.h
+++ w/run-command.h
@@ -204,7 +204,8 @@ int start_command(struct child_process *);
/**
* Wait for the completion of a sub-process that was started with
- * start_command().
+ * start_command(). The child_process structure is cleared and
+ * reinitialized.
*/
int finish_command(struct child_process *);
@@ -214,6 +215,9 @@ int finish_command_in_signal(struct child_process *);
* A convenience function that encapsulates a sequence of
* start_command() followed by finish_command(). Takes a pointer
* to a `struct child_process` that specifies the details.
+ * The child_process structure is cleared and reinitialized,
+ * even when the command fails to start or an error is detected
+ * in finish_command().
*/
int run_command(struct child_process *);
next prev parent reply other threads:[~2024-06-26 16:17 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-25 13:35 [PATCH v3] describe: refresh the index when 'broken' flag is used Abhijeet Sonar
2024-06-25 15:59 ` Junio C Hamano
2024-06-25 16:05 ` Junio C Hamano
2024-06-26 11:16 ` Karthik Nayak
2024-06-26 6:11 ` Abhijeet Sonar
2024-06-26 6:37 ` [PATCH v4] " Abhijeet Sonar
2024-06-26 6:50 ` Abhijeet Sonar
2024-06-26 6:52 ` [PATCH v5] " Abhijeet Sonar
2024-06-26 11:30 ` Karthik Nayak
2024-06-26 12:06 ` Abhijeet Sonar
2024-06-26 15:34 ` Re* " Junio C Hamano
2024-06-26 16:17 ` Junio C Hamano [this message]
2024-06-26 17:29 ` Abhijeet Sonar
2024-06-26 17:35 ` Junio C Hamano
2024-06-26 17:45 ` Junio C Hamano
2024-06-26 18:07 ` Abhijeet Sonar
2024-06-26 18:49 ` Junio C Hamano
2024-06-26 20:34 ` Jeff King
2024-06-27 0:33 ` Jeff King
2024-06-26 21:23 ` Karthik Nayak
2024-06-26 14:59 ` Junio C Hamano
2024-06-26 18:31 ` Junio C Hamano
2024-06-26 19:08 ` [PATCH v7] " Abhijeet Sonar
2024-06-26 19:25 ` Abhijeet Sonar
2024-06-27 6:01 ` Abhijeet Sonar
2024-06-27 15:47 ` Junio C Hamano
2024-06-27 17:33 ` Abhijeet Sonar
2024-06-30 16:12 ` Karthik Nayak
2024-07-01 19:06 ` Junio C Hamano
2024-07-02 10:13 ` Karthik Nayak
2024-07-03 18:17 ` Junio C Hamano
2024-07-03 20:41 ` Karthik Nayak
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