Re: [Qemu-devel] [PATCH 15/16] os-posix: cleanup: Replace perror with error_report

From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Ian Jackson <ian.jackson@citrix.com>
Cc: "Juergen Gross" <jgross@suse.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Markus Armbruster" <armbru@redhat.com>,
	"Michael Tokarev" <mjt@tls.msk.ru>,
	qemu-devel@nongnu.org, "Philippe Mathieu-Daudé" <f4bug@amsat.org>,
	"Ross Lagerwall" <ross.lagerwall@citrix.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Anthony PERARD" <anthony.perard@citrix.com>,
	xen-devel@lists.xenproject.org,
	"Alistair Francis" <alistair.francis@xilinx.com>
Subject: Re: [Qemu-devel] [PATCH 15/16] os-posix: cleanup: Replace perror with error_report
Date: Tue, 24 Apr 2018 16:18:30 +0100	[thread overview]
Message-ID: <20180424151830.GI20310@redhat.com> (raw)
In-Reply-To: <23263.17660.17771.980752@mariner.uk.xensource.com>

On Tue, Apr 24, 2018 at 03:53:48PM +0100, Ian Jackson wrote:
> Philippe Mathieu-Daudé writes ("Re: [Qemu-devel] [PATCH 15/16] os-posix: cleanup: Replace perror with error_report"):
> > On 04/19/2018 01:45 PM, Ian Jackson wrote:
> > > -        perror("mlockall");
> > > +        error_report("mlockall: %s", strerror(errno));
> > >      }
> > >  
> > >      return ret;
> > 
> > Thinking loudly, maybe we can refactor as error_report_errno(const char
> > *desc)...
> 
> git-grep 'error_report.*errno' shows a lot of call sites that do
> something more exciting than const char *desc would support.
> 
> I think the right approach would be
> 
>  - static void vreport(report_type type, const char *fmt, va_list ap)
>  + static void vreport(report_type type, int errnoval, const char *fmt, va_list ap)
> ...
>  +     if (errnoval >= 0) {
>  +         error_printf(": %s", strerror(errnoval);
>  +     }
> 
> and then add both
>   error_report_errno
>   error_vreport_errno
> with the obvious semantics.

That would be nice, because then we can make these two functions actually
use strerror_r() instead of strerror(), for thread safety on all platforms.

Regards,
Daniel
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