Re: [Xen-devel] [PATCH v2] symbols.c: Avoid warn_unused_result build failure on fgets().

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 11/09/15 11:06, Riku Voipio wrote:
> In commit:
> 
> d37d63d symbols: prefix static symbols with their source file names
> 
> An unchecked fgets was added. This causes a compile error at least
> on ubuntu utopic:
> 
> symbols.c: In function 'read_symbol':
> symbols.c:181:3: error: ignoring return value of 'fgets', declared with
> attribute warn_unused_result [-Werror=unused-result]
>    fgets(str, 500, in); /* discard rest of line */
>    ^
> 
> Paper over the warning by checking the return value in the if statement.
> 
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Signed-off-by: Riku Voipio <riku.voipio@xxxxxxxxxx>

Tested on Ubuntu 14.04.3 with GCC 4.8.4 and no 'warn_unused_result'
warnings any more.

Tested-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>

> ---
>  xen/tools/symbols.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/tools/symbols.c b/xen/tools/symbols.c
> index dbf6a1a..3b8fa39 100644
> --- a/xen/tools/symbols.c
> +++ b/xen/tools/symbols.c
> @@ -177,8 +177,8 @@ static int read_symbol(FILE *in, struct sym_entry *s)
>       rc = 0;
>  
>   skip_tail:
> -     if (input_format == fmt_sysv)
> -             fgets(str, 500, in); /* discard rest of line */
> +     if ((input_format == fmt_sysv) && fgets(str, 500, in) == NULL)
> +             return rc; /* discard rest of line and ignore errors */
>  
>       return rc;
>  }
> -- 
> 2.6.2
> 
> 
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