Am 05.10.22 um 09:29 schrieb Ævar Arnfjörð Bjarmason:
>
> On Tue, Oct 04 2022, René Scharfe wrote:
>
>> The strvec "argv" is used to build a command for run_command_v_opt(),
>> but never freed. Use the "args" strvec of struct child_process and
>> run_command() instead, which releases the allocated memory both on
>> success and on error. We just also need to set the "git_cmd" bit
>> directly.
>>
>> Signed-off-by: René Scharfe <l.s.r@xxxxxx>
>> ---
>> builtin/bisect--helper.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
>> index 501245fac9..9fe0c08479 100644
>> --- a/builtin/bisect--helper.c
>> +++ b/builtin/bisect--helper.c
>> @@ -765,11 +765,12 @@ static enum bisect_error bisect_start(struct bisect_terms *terms, const char **a
>> strbuf_read_file(&start_head, git_path_bisect_start(), 0);
>> strbuf_trim(&start_head);
>> if (!no_checkout) {
>> - struct strvec argv = STRVEC_INIT;
>> + struct child_process cmd = CHILD_PROCESS_INIT;
>>
>> - strvec_pushl(&argv, "checkout", start_head.buf,
>> + cmd.git_cmd = 1;
>> + strvec_pushl(&cmd.args, "checkout", start_head.buf,
>> "--", NULL);
>> - if (run_command_v_opt(argv.v, RUN_GIT_CMD)) {
>> + if (run_command(&cmd)) {
>> res = error(_("checking out '%s' failed."
>> " Try 'git bisect start "
>> "<valid-branch>'."),
>
> Okey, so we leak the strvec, and instead of adding a strvec_clear()
> you're just switching the lower-level API, which we'd need in some cases
> with this API, and would often be cleaner.
>
> But I don't get it in this case, why not just:
>
> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> index 4e97817fba5..f9645a9d0df 100644
> --- a/builtin/bisect--helper.c
> +++ b/builtin/bisect--helper.c
> @@ -763,11 +763,9 @@ static enum bisect_error bisect_start(struct bisect_terms *terms, const char **a
> strbuf_read_file(&start_head, git_path_bisect_start(), 0);
> strbuf_trim(&start_head);
> if (!no_checkout) {
> - struct strvec argv = STRVEC_INIT;
> + const char *argv[] = { "checkout", start_head.buf, "--", NULL };
>
> - strvec_pushl(&argv, "checkout", start_head.buf,
> - "--", NULL);
> - if (run_command_v_opt(argv.v, RUN_GIT_CMD)) {
> + if (run_command_v_opt(argv, RUN_GIT_CMD)) {
> res = error(_("checking out '%s' failed."
> " Try 'git bisect start "
> "<valid-branch>'."),
That looks even better. I didn't think of that because we had a phase
where we could only use constant expressions for initialization. We do
have a precedent in 359f0d754a (range-diff/format-patch: handle commit
ranges other than A..B, 2021-02-05), though, which does use a variable:
+ char *copy = xstrdup(arg); /* setup_revisions() modifies it */
+ const char *argv[] = { "", copy, "--", NULL };
(There may be earlier ones, that's just the one I found quickly.) So is
it time for that C99 feature already? Yay! 🥳
> The common pattern for run_command_v_opt() callers that don't need a
> dynamic list is exactly that, e.g.:
>
> builtin/difftool.c=static int print_tool_help(void)
> builtin/difftool.c-{
> builtin/difftool.c- const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
> builtin/difftool.c: return run_command_v_opt(argv, RUN_GIT_CMD);
> builtin/difftool.c-}
>
> And:
>
> fsmonitor-ipc.c=static int spawn_daemon(void)
> fsmonitor-ipc.c-{
> fsmonitor-ipc.c- const char *args[] = { "fsmonitor--daemon", "start", NULL };
> fsmonitor-ipc.c-
> fsmonitor-ipc.c: return run_command_v_opt_tr2(args, RUN_COMMAND_NO_STDIN | RUN_GIT_CMD,
> fsmonitor-ipc.c- "fsmonitor");
> fsmonitor-ipc.c-}
>
> Here we have the "start_head" which we'll need to strbuf_release(), but
> we're not returning directly, and the function is doing that already.
>
> Your version is slightly more memory efficient, i.e. we'll end up having
> to push this to a "struct child_process"'s argv anyway, but this is less
> code & we don't need to carefully eyeball run_command_v_opt_cd_env_tr2()
> to see that it's correct (which I did, your version does the right thing
> too).
Having two ways to set the same flags adds some unnecessary friction.
René
