Re: [Qemu-devel] [PATCH v2 1/5] util/qemu-sockets: Fix GCC 9 build warnings

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Apr 30, 2019 at 11:28:22PM +0000, Alistair Francis wrote:
> Fix this warning when building with GCC9 on Fedora 30:
> In function ‘strncpy’,
>     inlined from ‘unix_connect_saddr.isra.0’ at util/qemu-sockets.c:925:5:
> /usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 108 equals destination size [-Werror=stringop-truncation]
>   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
>       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In function ‘strncpy’,
>     inlined from ‘unix_listen_saddr.isra.0’ at util/qemu-sockets.c:880:5:
> 
> Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> ---
>  util/qemu-sockets.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
> index 9705051690..8c3322958f 100644
> --- a/util/qemu-sockets.c
> +++ b/util/qemu-sockets.c
> @@ -829,7 +829,7 @@ static int unix_listen_saddr(UnixSocketAddress *saddr,
>      struct sockaddr_un un;
>      int sock, fd;
>      char *pathbuf = NULL;
> -    const char *path;
> +    const char *path QEMU_NONSTRING;
>  
>      sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
>      if (sock < 0) {
> @@ -922,7 +922,7 @@ static int unix_connect_saddr(UnixSocketAddress *saddr, Error **errp)
>  
>      memset(&un, 0, sizeof(un));
>      un.sun_family = AF_UNIX;
> -    strncpy(un.sun_path, saddr->path, sizeof(un.sun_path));
> +    memcpy(un.sun_path, saddr->path, MIN(strlen(saddr->path), sizeof(un.sun_path)));
>  
>      /* connect to peer */
>      do {

I think my proposed fix for this file is preferrable as it avoids
repeated strlen calls 

  https://lists.gnu.org/archive/html/qemu-devel/2019-04/msg02124.html


Regards,
Daniel
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