[v2,4/4] examples/mp_server: clear string truncation warning

  Compiling with GCC 9.3 on Ubuntu 20.04 gives a warning about possible
string truncation when getting the RX queue name:

In file included from init.c:36:
init.c: In function ‘init’:
../shared/common.h:38:28: warning: ‘%u’ directive output may be truncated writing between 1 and 10 bytes into a region of size 8 [-Wformat-truncation=]
   38 | #define MP_CLIENT_RXQ_NAME "MProc_Client_%u_RX"
      |                            ^~~~~~~~~~~~~~~~~~~~
../shared/common.h:52:35: note: in expansion of macro ‘MP_CLIENT_RXQ_NAME’
   52 |  snprintf(buffer, sizeof(buffer), MP_CLIENT_RXQ_NAME, id);
      |                                   ^~~~~~~~~~~~~~~~~~

This is a false positive, as the value of the "id" is limited to 255, being
stored in the app as a uint8_t value, removing the possibility of the %u
being replaced by anything other then 3 characters max (rather than up to
10 as thought by the compiler). Therefore, the warning can be easily
removed by changing the type of the "id" parameter to the local function
from "unsigned" to "uint8_t" also, ensuring the compiler is aware of the
range limit.

Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 examples/multi_process/client_server_mp/shared/common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
  

On 8/21/2020 6:10 PM, Bruce Richardson wrote:
> Compiling with GCC 9.3 on Ubuntu 20.04 gives a warning about possible
> string truncation when getting the RX queue name:
>
> In file included from init.c:36:
> init.c: In function ‘init’:
> ../shared/common.h:38:28: warning: ‘%u’ directive output may be truncated writing between 1 and 10 bytes into a region of size 8 [-Wformat-truncation=]
>     38 | #define MP_CLIENT_RXQ_NAME "MProc_Client_%u_RX"
>        |                            ^~~~~~~~~~~~~~~~~~~~
> ../shared/common.h:52:35: note: in expansion of macro ‘MP_CLIENT_RXQ_NAME’
>     52 |  snprintf(buffer, sizeof(buffer), MP_CLIENT_RXQ_NAME, id);
>        |                                   ^~~~~~~~~~~~~~~~~~
>
> This is a false positive, as the value of the "id" is limited to 255, being
> stored in the app as a uint8_t value, removing the possibility of the %u
> being replaced by anything other then 3 characters max (rather than up to
> 10 as thought by the compiler). Therefore, the warning can be easily
> removed by changing the type of the "id" parameter to the local function
> from "unsigned" to "uint8_t" also, ensuring the compiler is aware of the
> range limit.
>
> Cc: stable@dpdk.org
>
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
Acked-by: Radu Nicolau <radu.nicolau@intel.com>