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

[Laurent Vivier]

Le 30/04/2019 à 23:01, Alistair Francis a écrit :
> On Tue, Apr 30, 2019 at 1:36 PM Laurent Vivier <address@hidden> wrote:
>>
>> 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 :)
> 
> GCC can't read the comment though. The only other option I can think
> of is using a pragma, which I avoided using unless I had to. Would you
> prefer a pragma here? Or do you have a better solution?
> 

perhaps:

memcpy(psinfo->pr_fname, base_filename, MIN(strlen(base_filename) + 1, 
sizeof(psinfo->pr_fname));

?

Thanks,
Laurent