Re: [PATCH v2] migration: Silence compiler warning in global_state_store_running()

[Philippe Mathieu-Daudé]

On 9/17/20 9:43 AM, Thomas Huth wrote:
> GCC 9.3.0 on Ubuntu complains:
> 
> In file included from /usr/include/string.h:495,
>                  from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
>                  from ../migration/global_state.c:13:
> In function ‘strncpy’,
>     inlined from ‘global_state_store_running’ at 
> ../migration/global_state.c:47:5:
> /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error:
>  ‘__builtin_strncpy’ specified bound 100 equals destination size 
> [-Werror=stringop-truncation]
>   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos 
> (__dest));
>       |          
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> ... but we apparently really want to do a strncpy here - the size is already
> checked with the assert() statement right in front of it. To silence the
> warning, simply replace it with our strpadcpy() function.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  v2: Use strpadcpy instead of QEMU_NONSTRING (and yes, this time it seems
>      to really silence the compiler warning :-))
> 
>  migration/global_state.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/global_state.c b/migration/global_state.c
> index 25311479a4..a33947ca32 100644
> --- a/migration/global_state.c
> +++ b/migration/global_state.c
> @@ -44,8 +44,8 @@ void global_state_store_running(void)
>  {
>      const char *state = RunState_str(RUN_STATE_RUNNING);
>      assert(strlen(state) < sizeof(global_state.runstate));
> -    strncpy((char *)global_state.runstate,
> -           state, sizeof(global_state.runstate));
> +    strpadcpy((char *)global_state.runstate, sizeof(global_state.runstate),
> +              state, '\0');

https://www.mail-archive.com/qemu-block@nongnu.org/msg44925.html
;)

>  }
>  
>  bool global_state_received(void)
>