Re: [PATCH 1/3] tools/nolibc: fix fopen() errno when open() fails

[Thomas Weißschuh]

On 2026-10-28 15:07:41-0500, Danish Khateeb wrote:
> When open() fails, fopen() passes its -1 on to fdopen(), which sets
> errno to EBADF and so overwrites the error from open(). A missing file
> is reported as EBADF instead of ENOENT, and a file without permission as
> EBADF instead of EACCES.
> 
> Return NULL as soon as open() fails, leaving its errno in place.
> 
> Fixes: a009a0c6faa9 ("tools/nolibc: add fopen()")
> Signed-off-by: Danish Khateeb <danishkhateeb03@xxxxxxxxx>

Thanks!

Reviewed-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>

> ---
>  tools/include/nolibc/stdio.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
> index ebdd413d13ec..00a95a267d90 100644
> --- a/tools/include/nolibc/stdio.h
> +++ b/tools/include/nolibc/stdio.h
> @@ -79,6 +79,9 @@ FILE *fopen(const char *pathname, const char *mode)
>  		flags = (flags & ~(O_RDONLY | O_WRONLY)) | O_RDWR;
>  
>  	fd = open(pathname, flags, 0666);
> +	if (fd < 0)
> +		return NULL;
> +
>  	return fdopen(fd, mode);
>  }