Re: [Qemu-devel] [PATCH v6 10/10] block/vvfat: fix setbuf stream parameter may be NULL

[Michael S. Tsirkin]

On Thu, Aug 14, 2014 at 03:29:21PM +0800, zhanghailiang wrote:
> From: Li Liu <address@hidden>
> 
> fopen() may return NULL which will cause setbuf() segmentfault
> 
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Li Liu <address@hidden>
> ---
>  block/vvfat.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/block/vvfat.c b/block/vvfat.c
> index 70176b1..6889ea9 100644
> --- a/block/vvfat.c
> +++ b/block/vvfat.c
> @@ -1084,7 +1084,10 @@ static int vvfat_open(BlockDriverState *bs, QDict 
> *options, int flags,
>  
>  DLOG(if (stderr == NULL) {
>      stderr = fopen("vvfat.log", "a");
> -    setbuf(stderr, NULL);
> +
> +    if (stderr) {
> +        setbuf(stderr, NULL);
> +    }
>  })
>  
>      opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);

I would say assert on failure here.
If one is trying to debug, seeing no output will just confuse
matters more.

> -- 
> 1.7.12.4
>