linux-kernel - Re: [PATCH v3 03/12] tools/nolibc/stdio: let perror work when NOLIBC_IGNORE

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Message-ID: <8428cee5-d739-44a7-8253-93f663f9e969@t-8ch.de>
Date: Thu, 25 Sep 2025 18:22:49 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Benjamin Berg <benjamin@...solutions.net>
Cc: linux-um@...ts.infradead.org, Willy Tarreau <w@....eu>, 
	linux-kselftest@...r.kernel.org, Arnaldo Carvalho de Melo <acme@...hat.com>, 
	linux-kernel@...r.kernel.org, Benjamin Berg <benjamin.berg@...el.com>
Subject: Re: [PATCH v3 03/12] tools/nolibc/stdio: let perror work when
 NOLIBC_IGNORE_ERRNO is set

On 2025-09-24 16:20:50+0200, Benjamin Berg wrote:
> From: Benjamin Berg <benjamin.berg@...el.com>
> 
> There is no errno variable when NOLIBC_IGNORE_ERRNO is defined. As such,
> simply print the message with "unknown error" rather than the integer
> value of errno.
> 
> Fixes: acab7bcdb1bc ("tools/nolibc/stdio: add perror() to report the errno value")
> Signed-off-by: Benjamin Berg <benjamin.berg@...el.com>

Acked-by: Thomas Weißschuh <linux@...ssschuh.net>

> 
> ---
> v3:
> - Change the message instead of removing perror entirely
> ---
>  tools/include/nolibc/stdio.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
> index 7630234408c5..724d05ce6962 100644
> --- a/tools/include/nolibc/stdio.h
> +++ b/tools/include/nolibc/stdio.h
> @@ -600,7 +600,11 @@ int sscanf(const char *str, const char *format, ...)
>  static __attribute__((unused))
>  void perror(const char *msg)
>  {
> +#ifdef NOLIBC_IGNORE_ERRNO
> +	fprintf(stderr, "%s%sunknown error\n", (msg && *msg) ? msg : "", (msg && *msg) ? ": " : "");
> +#else
>  	fprintf(stderr, "%s%serrno=%d\n", (msg && *msg) ? msg : "", (msg && *msg) ? ": " : "", errno);
> +#endif
>  }
>  
>  static __attribute__((unused))
> -- 
> 2.51.0
>