On 04/21/2014 12:23 AM, Fam Zheng wrote: > Previously, when there is an user error in argv parsing, qemu-img prints
s/an user/a user/
(The rule of thumb for selecting which article to use for a leading 'u'
is pronunciation: anything starting with "you" uses "a", anything with
"uh" uses "an" [e.g. a unicorn under an umbrella]. Similar confusion
for 'h': hard h uses "a", silent h uses "an" [e.g. an hour and a half])
> help text and exits.
>
> Add an error_exit function to print a helpful error message and a hint
> to run 'qemu-img --help' for more information.
>
> As a bonus, "qemu-img <cmd> --help" now has a more reasonable exit code
> 0.
>
> In the future the help text should be split by sub command, and only
> print the information for the specified command.
>
> Signed-off-by: Fam Zheng <f...@redhat.com>
> ---
> qemu-img.c | 71
> +++++++++++++++++++++++++++++++++++++++-----------------------
> 1 file changed, 45 insertions(+), 26 deletions(-)
>
> +static void GCC_FMT_ATTR(1, 2) error_exit(const char *fmt, ...)
Should you also mark this QEMU_NORETURN?
> +{
> + va_list ap;
> +
> + error_printf("qemu-img: ");
> +
> + va_start(ap, fmt);
> + error_vprintf(fmt, ap);
> + va_end(ap);
> +
> + error_printf("\nTry 'qemu-img --help' for more information\n");
> + exit(1);
Worth using EXIT_FAILURE?
> @@ -129,7 +143,7 @@ static void help(void)
> printf("%s\nSupported formats:", help_msg);
> bdrv_iterate_format(format_print, NULL);
> printf("\n");
> - exit(1);
> + exit(0);
Worth using EXIT_SUCCESS?
> @@ -2046,10 +2061,10 @@ static int img_map(int argc, char **argv)
> break;
> }
> }
> - if (optind >= argc) {
> - help();
> + if (optind != argc - 1) {
> + error_exit("Expecting one image file name");
> }
> - filename = argv[optind++];
> + filename = argv[optind];
I had to look at context to see that the increment of optind was indeed
dead code worth removing.
> @@ -2788,6 +2807,6 @@ int main(int argc, char **argv)
> }
>
> /* not found */
> - help();
> + error_exit("Command not found: %s", cmdname);
> return 0;
This return is now dead code; using QEMU_NORETURN would have helped the
compiler flag it.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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