Re: [Qemu-trivial] [PATCH v1 4/5] linux-user/uname: 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 ‘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.

Thanks,
Laurent