Re: [PATCH] examples/cmdline: fix build error with gcc 12

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 1/18/2023 4:11 PM, Bruce Richardson wrote:
> When building the example without libbsd and using the DPDK-provided
> strlcpy function, a compiler warning is emitted by GCC 12 about the copy
> of the parsed string into the resulting object. This is because the
> source from cmdline library is 128 bytes and the destination buffer is
> 64-bytes.
> 
> commands.c: In function 'cmd_obj_add_parsed':
> .../__BUILDS/build-x86-generic/install/usr/local/include/rte_string_fns.h:61:24: warning: '%s' directive output may be truncated writing up to 127 bytes into a region of size 64 [-Wformat-truncation=]
>    61 |         return (size_t)snprintf(dst, size, "%s", src);
>       |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from /usr/include/stdio.h:894,
>                  from commands.c:7:
> /usr/include/x86_64-linux-gnu/bits/stdio2.h:71:10: note: '__builtin_snprintf' output between 1 and 128 bytes into a destination of size 64
> 
> Multiple options are possible to fix this, but the one taken in this
> patch is to ensure truncation never occurs by setting the destination
> buffer size to be the same as that used by the cmdline library.
> 
> Fixes: af75078fece3 ("first public release")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  examples/cmdline/parse_obj_list.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/examples/cmdline/parse_obj_list.h b/examples/cmdline/parse_obj_list.h
> index 6516d3e2c2..1223ac1e8b 100644
> --- a/examples/cmdline/parse_obj_list.h
> +++ b/examples/cmdline/parse_obj_list.h
> @@ -12,8 +12,9 @@
>  
>  #include <sys/queue.h>
>  #include <cmdline_parse.h>
> +#include <cmdline_parse_string.h>
>  
> -#define OBJ_NAME_LEN_MAX 64
> +#define OBJ_NAME_LEN_MAX sizeof(cmdline_fixed_string_t)
>  
>  struct object {
>  	SLIST_ENTRY(object) next;

I confirm it solves the build warning, but what about to get rid of
`OBJ_NAME_LEN_MAX` completely if the intentions is to make size same as
cmdline library array:

 diff --git a/examples/cmdline/parse_obj_list.c
b/examples/cmdline/parse_obj_list.c
 index 959bcd14527e..7b24bfb035d7 100644
 --- a/examples/cmdline/parse_obj_list.c
 +++ b/examples/cmdline/parse_obj_list.c
 @@ -46,7 +46,7 @@ parse_obj_list(cmdline_parse_token_hdr_t *tk, const
char *buf, void *res,
                 token_len++;

         SLIST_FOREACH(o, tkd->list, next) {
 -               if (token_len != strnlen(o->name, OBJ_NAME_LEN_MAX))
 +               if (token_len != strnlen(o->name, STR_TOKEN_SIZE))
                         continue;
                 if (strncmp(buf, o->name, token_len))
                         continue;
 @@ -91,7 +91,7 @@ int
complete_get_elt_obj_list(cmdline_parse_token_hdr_t *tk,
         if (!o)
                 return -1;

 -       len = strnlen(o->name, OBJ_NAME_LEN_MAX);
 +       len = strnlen(o->name, STR_TOKEN_SIZE);
         if ((len + 1) > size)
                 return -1;

 diff --git a/examples/cmdline/parse_obj_list.h
b/examples/cmdline/parse_obj_list.h
 index 6516d3e2c236..ba234601f106 100644
 --- a/examples/cmdline/parse_obj_list.h
 +++ b/examples/cmdline/parse_obj_list.h
 @@ -12,12 +12,11 @@

  #include <sys/queue.h>
  #include <cmdline_parse.h>
 -
 -#define OBJ_NAME_LEN_MAX 64
 +#include <cmdline_parse_string.h>

  struct object {
         SLIST_ENTRY(object) next;
 -       char name[OBJ_NAME_LEN_MAX];
 +       cmdline_fixed_string_t name;
         cmdline_ipaddr_t ip;
  };