Re: [Qemu-devel] [PATCH v2] sockets: avoid string truncation warnings when copying UNIX path

[Stefano Garzarella]

On Wed, May 01, 2019 at 03:50:52PM +0100, Daniel P. Berrangé wrote:
> In file included from /usr/include/string.h:494,
>                  from include/qemu/osdep.h:101,
>                  from util/qemu-sockets.c:18:
> 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: warning: ‘__builtin_strncpy’ 
> specified bound 108 equals destination size [-Wstringop-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:
> /usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ 
> specified bound 108 equals destination size [-Wstringop-truncation]
>   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos 
> (__dest));
>       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> We are already validating the UNIX socket path length earlier in
> the functions. If we save this string length when we first check
> it, then we can simply use memcpy instead of strcpy later, avoiding
> the gcc truncation warnings.
> 
> Signed-off-by: Daniel P. Berrangé <address@hidden>
> ---
>  util/qemu-sockets.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)

Reviewed-by: Stefano Garzarella <address@hidden>