Re: [Qemu-devel] [PATCH v1 4/5] linux-user/uname: Fix GCC 9 build warnings

[Laurent Vivier]

Le 30/04/2019 à 22:30, Laurent Vivier a écrit :
> 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 ‘sys_uname’ at /home/alistair/qemu/linux-user/uname.c:94:3:
>> /usr/include/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ 
>> output may be truncated copying 64 bytes from a string of length 64 
>> [-Werror=stringop-truncation]
>>   106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos 
>> (__dest));
>>       |          
>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Signed-off-by: Alistair Francis <address@hidden>
>> ---
>>  linux-user/uname.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/linux-user/uname.c b/linux-user/uname.c
>> index 313b79dbad..293b2238f2 100644
>> --- a/linux-user/uname.c
>> +++ b/linux-user/uname.c
>> @@ -90,6 +90,11 @@ int sys_uname(struct new_utsname *buf)
>>     * struct linux kernel uses).
>>     */
>>  
>> +#if defined(CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE) && QEMU_GNUC_PREREQ(9, 0)
>> +#pragma GCC diagnostic push
>> +#pragma GCC diagnostic ignored "-Wstringop-truncation"
>> +#endif
>> +
>>    memset(buf, 0, sizeof(*buf));
>>    COPY_UTSNAME_FIELD(buf->sysname, uts_buf.sysname);
>>    COPY_UTSNAME_FIELD(buf->nodename, uts_buf.nodename);
>> @@ -101,6 +106,9 @@ int sys_uname(struct new_utsname *buf)
>>  #endif
>>    return (0);
>>  
>> +#if defined(CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE) && QEMU_GNUC_PREREQ(9, 0)
>> +#pragma GCC diagnostic pop
>> +#endif
>>  #undef COPY_UTSNAME_FIELD
>>  }
>>  
>>
> 
> You should use PRAGMA_DISABLE_PACKED_WARNING and
> PRAGMA_REENABLE_PACKED_WARNING from linux-user/qemu.h.

Ok, I should read correctly, the pragma here is not related to them

Thanks,
Laurent