Re: [hackers] [dwm][PATCH] Fix bug in die()

From: Hiltjo Posthuma <hiltjo_AT_codemadness.org>
Date: Sun, 27 Oct 2024 18:27:13 +0100

On Sun, Oct 27, 2024 at 03:05:37PM +0000, Raymond Cole wrote:
> fputc() might set errno and thus affect perror().
> ---
> util.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/util.c b/util.c
> index 96b82c9..a289160 100644
> --- a/util.c
> +++ b/util.c
> _AT_@ -1,4 +1,5 @@
> /* See LICENSE file for copyright and license details. */
> +#include <errno.h>
> #include <stdarg.h>
> #include <stdio.h>
> #include <stdlib.h>
> _AT_@ -15,12 +16,9 @@ die(const char *fmt, ...)
> vfprintf(stderr, fmt, ap);
> va_end(ap);
>
> - if (fmt[0] && fmt[strlen(fmt)-1] == ':') {
> - fputc(' ', stderr);
> - perror(NULL);
> - } else {
> - fputc('\n', stderr);
> - }
> + if (fmt[0] && fmt[strlen(fmt)-1] == ':')
> + fprintf(stderr, " %s", strerror(errno));
> + fputc('\n', stderr);
>
> exit(1);
> }
> --
> 2.46.2
>
>

Thanks for the patch. I agree and the common pattern is even, at the top of
the function:

        int saved_errno = errno;

Then use (or restore) errno.
I notice dmenu, dwm, libsl, sbase, etc have this bug.

-- 
Kind regards,
Hiltjo
Received on Sun Oct 27 2024 - 18:27:13 CET

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