Re: [Qemu-devel] [PATCH] Check fread() results to avoid gcc 4.6 warnings

[Anthony Liguori]

On 08/01/2011 01:49 AM, David Gibson wrote:
> When compiling with gcc 4.6, some code in fw_cfg.c complains that fop_ret
> is assigned but not used (which is true).  However, it looks like the
> meaningless assignments to fop_ret were done to suppress other gcc warnings
> due to the fact that fread() is labelled as warn_unused_result in glibc.
>
> This patch avoids both errors, by actually checking the fread() result code
> and dropping out with an error message if it fails.
>
> Signed-off-by: David Gibson<address@hidden>

Applied.  Thanks.

Regards,

Anthony Liguori

> ---
>   hw/fw_cfg.c |   13 +++++++++++++
>   1 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/hw/fw_cfg.c b/hw/fw_cfg.c
> index a29db90..e4847b7 100644
> --- a/hw/fw_cfg.c
> +++ b/hw/fw_cfg.c
> @@ -87,6 +87,13 @@ static FILE *probe_splashfile(char *filename, int 
> *file_sizep, int *file_typep)
>       /* check magic ID */
>       fseek(fp, 0L, SEEK_SET);
>       fop_ret = fread(buf, 1, 2, fp);
> +    if (fop_ret != 2) {
> +        error_report("Could not read header from '%s': %s",
> +                     filename, strerror(errno));
> +        fclose(fp);
> +        fp = NULL;
> +        return fp;
> +    }
>       filehead_value = (buf[0] + (buf[1]<<  8))&  0xffff;
>       if (filehead_value == 0xd8ff) {
>           file_type = JPG_FILE;
> @@ -181,6 +188,12 @@ static void fw_cfg_bootsplash(FWCfgState *s)
>           boot_splash_filedata_size = file_size;
>           fseek(fp, 0L, SEEK_SET);
>           fop_ret = fread(boot_splash_filedata, 1, file_size, fp);
> +        if (fop_ret != file_size) {
> +            error_report("failed to read data from '%s'.",
> +                         boot_splash_filename);
> +            fclose(fp);
> +            return;
> +        }
>           fclose(fp);
>           /* insert data */
>           if (file_type == JPG_FILE) {