Re: [Qemu-devel] [PATCH 03/22] vmdk: relative_path: avoid buffer overrun

[Kevin Wolf <kwolf@redhat.com>]

Am 09.05.2012 11:23, schrieb Jim Meyering:
> From: Jim Meyering <meyering@redhat.com>
> 
> strncpy does not guarantee NUL-termination.
> Setting dest[n-1] = '\0' *before* calling strncpy(dest, src, n-1)
> is a no-op.  Use pstrcpy to ensure NUL-termination, not strncpy.

It's not, it would only be a no-op before strncpy(dest, src, n). But
pstrcpy() is definitely nicer.

> Signed-off-by: Jim Meyering <meyering@redhat.com>
> ---
>  block/vmdk.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 18e9b4c..045e279 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -1319,8 +1319,7 @@ static int relative_path(char *dest, int dest_size,
>          return -1;
>      }
>      if (path_is_absolute(target)) {
> -        dest[dest_size - 1] = '\0';
> -        strncpy(dest, target, dest_size - 1);
> +        pstrcpy(dest, dest_size - 1, target);

I think you mean pstrcpy(dest, dest_size, target).

>          return 0;
>      }
>      while (base[i] == target[i]) {

Kevin