Re: [Qemu-trivial] [PATCH v1 5/5] linux-user/elfload: Fix GCC 9 build warnings

[Laurent Vivier]

Le 30/04/2019 à 22:09, Alistair Francis a écrit :
> Fix this warning when building with GCC9 on Fedora 30:
> In function ‘strncpy’,
>     inlined from ‘fill_psinfo’ at 
> /home/alistair/qemu/linux-user/elfload.c:3208:12,
>     inlined from ‘fill_note_info’ at 
> /home/alistair/qemu/linux-user/elfload.c:3390:5,
>     inlined from ‘elf_core_dump’ at 
> /home/alistair/qemu/linux-user/elfload.c:3539:9:
> /usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ 
> specified bound 16 equals destination size [-Werror=stringop-truncation]
>   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos 
> (__dest));
>       |          
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Signed-off-by: Alistair Francis <address@hidden>
> ---
>  linux-user/elfload.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index c1a26021f8..cbb7fc10fa 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -3206,7 +3206,7 @@ static int fill_psinfo(struct target_elf_prpsinfo 
> *psinfo, const TaskState *ts)

       /*
        * Using strncpy here is fine: at max-length,
>       * this field is not NUL-terminated.
>       */>      (void) strncpy(psinfo->pr_fname, base_filename,
> -                   sizeof(psinfo->pr_fname));
> +                   sizeof(psinfo->pr_fname) - 1);

Read the comment above :)

>  
>      g_free(base_filename);
>      bswap_psinfo(psinfo);
> @@ -3389,7 +3389,7 @@ static int fill_note_info(struct elf_note_info *info,
>                sizeof (*info->prstatus), info->prstatus);
>      fill_psinfo(info->psinfo, ts);
>      fill_note(&info->notes[1], "CORE", NT_PRPSINFO,
> -              sizeof (*info->psinfo), info->psinfo);
> +              sizeof(*info->psinfo) - 1, info->psinfo);

Why?

>      fill_auxv_note(&info->notes[2], ts);
>      info->numnote = 3;
>  
> 

Thanks,
Laurent