Re: [PATCH] libio: Add __nonnull for FILE * arguments of fclose and freopen

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 21/04/23 03:21, Xi Ruoyao wrote:
> Calling fclose or freopen with a null FILE * is undefined behavior, and
> doing so in practice will cause a SIGSEGV.  So it seems suitable for
> __nonnull.
> 
> This will help the compiler to warn for some buggy code, like
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109570.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  libio/stdio.h | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/libio/stdio.h b/libio/stdio.h
> index 45ddafdf20..bfb8415d3b 100644
> --- a/libio/stdio.h
> +++ b/libio/stdio.h
> @@ -180,7 +180,7 @@ extern int renameat2 (int __oldfd, const char *__old, int __newfd,
>  
>     This function is a possible cancellation point and therefore not
>     marked with __THROW.  */
> -extern int fclose (FILE *__stream);
> +extern int fclose (FILE *__stream) __nonnull ((1));
>  
>  #undef __attr_dealloc_fclose
>  #define __attr_dealloc_fclose __attr_dealloc (fclose, 1)
> @@ -269,7 +269,7 @@ extern FILE *fopen (const char *__restrict __filename,
>     marked with __THROW.  */
>  extern FILE *freopen (const char *__restrict __filename,
>  		      const char *__restrict __modes,
> -		      FILE *__restrict __stream) __wur;
> +		      FILE *__restrict __stream) __wur __nonnull ((3));
>  #else
>  # ifdef __REDIRECT
>  extern FILE *__REDIRECT (fopen, (const char *__restrict __filename,
> @@ -290,7 +290,7 @@ extern FILE *fopen64 (const char *__restrict __filename,
>    __attribute_malloc__ __attr_dealloc_fclose __wur;
>  extern FILE *freopen64 (const char *__restrict __filename,
>  			const char *__restrict __modes,
> -			FILE *__restrict __stream) __wur;
> +			FILE *__restrict __stream) __wur __nonnull ((3));
>  #endif
>  
>  #ifdef	__USE_POSIX