Re: [PULL 4/4] qapi/error: Check format string argument in error_*prepend()

[Philippe Mathieu-Daudé]

On 7/24/20 4:08 PM, Daniel P. Berrangé wrote:
> On Fri, Jul 24, 2020 at 03:47:04PM +0200, Markus Armbruster wrote:
>> From: Philippe Mathieu-Daudé <philmd@redhat.com>
>>
>> error_propagate_prepend() "behaves like error_prepend()", and
>> error_prepend() uses "formatting @fmt, ... like printf()".
>> error_prepend() checks its format string argument, but
>> error_propagate_prepend() does not. Fix by addint the format
>> attribute to error_propagate_prepend() and error_vprepend().
>>
>> This would have caught the bug fixed in the previous commit.
>>
>> Missed in commit 4b5766488f "error: Fix use of error_prepend() with
>> &error_fatal, &error_abort".
> 
> FWIW, I'd suggest a followup patch that adds -Wsuggest-attribute=format
> to CFLAGS, as after a quick hack to try a build, I think all the things
> it reports are valid cases needing the format attribute.
> 
> qemu/util/error.c:62:5: warning: function ‘error_setv’ might be a candidate 
> for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
> qemu/util/error.c:133:5: warning: function ‘error_vprepend’ might be a 
> candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
> qemu/util/qemu-error.c:236:5: warning: function ‘vreport’ might be a 
> candidate for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]
> qemu/contrib/libvhost-user/libvhost-user.c:161:5: warning: function 
> ‘vu_panic’ might be a candidate for ‘gnu_printf’ format attribute 
> [-Wsuggest-attribute=format]
> qemu/tools/virtiofsd/fuse_log.c:20:5: warning: function ‘default_log_func’ 
> might be a candidate for ‘gnu_printf’ format attribute 
> [-Wsuggest-attribute=format]
> qemu/tools/virtiofsd/passthrough_ll.c:2752:9: warning: function ‘log_func’ 
> might be a candidate for ‘gnu_printf’ format attribute 
> [-Wsuggest-attribute=format]
> qemu/tools/virtiofsd/passthrough_ll.c:2754:9: warning: function ‘log_func’ 
> might be a candidate for ‘gnu_printf’ format attribute 
> [-Wsuggest-attribute=format]
> qemu/hw/xen/xen-bus-helper.c:124:9: warning: function ‘xs_node_vscanf’ might 
> be a candidate for ‘gnu_scanf’ format attribute [-Wsuggest-attribute=format]
> qemu/disas.c:497:5: warning: function ‘plugin_printf’ might be a candidate 
> for ‘gnu_printf’ format attribute [-Wsuggest-attribute=format]

I have the printf() ones ready but am waiting to be closer to 5.2.

> 
> 
> Regards,
> Daniel
>