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

["Daniel P. Berrangé" <berrange@redhat.com>]

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]


Regards,
Daniel
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