On Wed, Nov 24, 2021 at 11:54:09AM -0300, Enzo Matsumiya wrote:
> When prepare_cmd() fails for, e.g., pager process setup,
> child_process_clear() frees the memory in pager_process.args, but .argv
> was pointed to pager_process.args.v earlier in start_command(), so it's
> now a dangling pointer.
>
> setup_pager() is then called a second time, from cmd_log_init_finish()
> in this case, and any further operations using its .argv, e.g. strvec_*,
> will use the dangling pointer and eventually crash. According to trivial
> tests, setup_pager() is not called twice if the first call is
> successful.
>
> This patch makes sure that pager_process is properly initialized on
> setup_pager().
>
> Add a test to catch possible regressions.
Oh, good. I just replied in the separate thread suggesting this
direction, but I see you had already sent this. :)
This patch looks good to me. Two small nits:
> diff --git a/pager.c b/pager.c
> index 52f27a6765c8..d93304527d62 100644
> --- a/pager.c
> +++ b/pager.c
> @@ -124,6 +124,8 @@ void setup_pager(void)
>
> setenv("GIT_PAGER_IN_USE", "true", 1);
>
> + child_process_init(&pager_process);
> +
You could drop the CHILD_PROCESS_INIT initializer in the declaration of
pager_process now. I'm OK with keeping it, though, as a
belt-and-suspenders thing. If we don't run setup_pager() at all I don't
think anybody should look at it (since we won't have installed our
signal/atexit cleanup handlers), but it doesn't hurt.
> diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh
> index 0e7cf75435ec..0be9bcba49a8 100755
> --- a/t/t7006-pager.sh
> +++ b/t/t7006-pager.sh
> @@ -786,4 +786,9 @@ test_expect_success TTY 'git returns SIGPIPE on propagated signals from pager' '
> test_path_is_file pager-used
> '
>
> +test_expect_success TTY 'handle attempt to run an invalid pager' '
> + test_config pager.show invalid-pager &&
> + test_terminal git show
> +'
Yep, this should trigger the bug. I agree with Eric that "non-existent"
is probably more descriptive, as the key thing here is that
start_command() fails immediately, rather than us piping to the broken
pager.
-Peff
