Re: [PATCH] grep: correctly initialize help-all option
Am 09.04.2015 um 15:41 schrieb Patrick Steinhardt:
> The "help-all" option is being initialized with a wrong value.
> While being semantically wrong this can also cause a gcc
> segmentation fault on ARMv7 hardfloat platforms with a hardened
> toolchain. Fix this by initializing with the correct value.
Thanks for your report and patch. A few comments:
Sign-off? (See "Sign your work" in Documentation/SubmittingPatches)
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> ---
> builtin/grep.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/builtin/grep.c b/builtin/grep.c
> index abc4400..c0bf005 100644
> --- a/builtin/grep.c
> +++ b/builtin/grep.c
> @@ -738,7 +738,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
> PARSE_OPT_OPTARG, NULL, (intptr_t)default_pager },
> OPT_BOOL(0, "ext-grep", &external_grep_allowed__ignored,
> N_("allow calling of grep(1) (ignored by this build)")),
> - { OPTION_CALLBACK, 0, "help-all", &options, NULL, N_("show usage"),
> + { OPTION_CALLBACK, 0, "help-all", &opt, NULL, N_("show usage"),
> PARSE_OPT_HIDDEN | PARSE_OPT_NOARG, help_callback },
> OPT_END()
> };help_callback() returns -1 immediately, IOW the value pointer is never used anyway. So why does your change make a difference? *puzzled*
We could pass NULL instead, as in builtin/show-ref.c, which would make it clear that the pointer is just a dummy.
Q: Why does the callback exist in the first place? A: parse_options()
handles -h and --help-all automatically by showing the list of available
options. This is good for most commands for consistency's sake, but bad
for commands that want to use -h for something else. That's why it can
be turned off with the flag PARSE_OPT_NO_INTERNAL_HELP, but that flag
disables the long option as well. It's added back by grep and show-ref
explicitly, to at least provide --help-all consistently across all commands.
We could solve this problem centrally by checking for -h and --help-all only after looking through the struct option list supplied to parse_options_step() instead of before and getting rid of the then unneeded callbacks for --help-all in grep and show-ref. Are there any downsides to that approach?
René
Patrick Steinhardt
