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Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' inst
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments |
Date: |
Mon, 19 Jun 2017 09:48:44 +0100 |
User-agent: |
Mutt/1.8.2 (2017-04-18) |
* Eduardo Habkost (address@hidden) wrote:
> On Thu, Jun 15, 2017 at 01:14:15PM +0100, Dr. David Alan Gilbert wrote:
> > * Eduardo Habkost (address@hidden) wrote:
> > > This is being included in the RFC just to help validating the series,
> > > and ensure we don't use NULL errp anywhere.
> > >
> > > I don't propose we actually change all code to use the
> > > 'Error *errp[static 1]' syntax because it confuses Cocinelle.
> > >
> > > I am considering including a assert(errp) line in the ERR_IS_SET()
> > > macro, so we can catch NULL errp at runtime in case somebody forgets
> > > about it.
> > >
> > > Generated by the following Coccinelle patch:
> > >
> > > @@
> > > typedef Error;
> > > type T;
> > > identifier FN !~ "os_mem_prealloc|qemu_fork";
> > > identifier errp;
> > > @@
> > > T FN(...,
> > > - Error **errp
> > > + Error *errp[STATIC_1]
> > > );
> > >
> > > @@
> > > typedef Error;
> > > type T;
> > > identifier FN !~ "os_mem_prealloc|qemu_fork";
> > > identifier errp;
> > > @@
> > > T FN(...,
> > > - Error **errp
> > > + Error *errp[STATIC_1]
> > > ) { ... }
> > >
> > > Followed by the following sed command:
> > >
> > > $ sed -i -e 's/\[STATIC_1\]/[static 1]/g' $(g grep -w -l STATIC_1)
> > >
> > > Signed-off-by: Eduardo Habkost <address@hidden>
> > > ---
> >
> > <snip>
> >
> > > void visit_start_struct(Visitor *v, const char *name, void **obj,
> > > - size_t size, Error **errp);
> > > + size_t size, Error *errp[static 1]);
> > >
> >
> > Is it possible to typedef that to something that hides the magic syntax?
> > Then we could get that down to QError errp or something like that?
>
> Unfortunately it is not possible to hide it in a typedef: the
> "static" keyword inside the square brackets is a feature of
> function parameter declarations only. Using it on a typedef
> results in:
>
> a.c:3:16: error: static or type qualifiers in non-parameter array declarator
> typedef Error *ErrorPtr[static 1];
That's a shame; it's rather odd looking; still I think it's
worth it if it simplifies the error code.
> We could use a preprocessor macro, but I suspect this would also
> confuse Coccinelle.
>
> --
> Eduardo
Dave
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [RFC 07/15] Manual changes to use IGNORE_ERRORS instead of NULL, (continued)
- [Qemu-devel] [RFC 07/15] Manual changes to use IGNORE_ERRORS instead of NULL, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 10/15] test-qapi-util: Use ERR_IS_* macros, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 11/15] Manual changes to use ERR_IS_* macros, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 09/15] [coccinelle] Use ERR_IS_* macros, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 12/15] error: Make IGNORED_ERRORS not a NULL pointer, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 13/15] rdma: Simplify var declaration to avoid confusing Coccinelle, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 04/15] [coccinelle] Use IGNORE_ERRORS instead of NULL as errp argument, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 14/15] [coccinelle] Eliminate unnecessary local_err/error_propagate() usage, Eduardo Habkost, 2017/06/13
- [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments, Eduardo Habkost, 2017/06/13
- Message not available
- Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments, Eduardo Habkost, 2017/06/17
- Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments, Peter Maydell, 2017/06/19
- Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments, Eduardo Habkost, 2017/06/19
- Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments, Eric Blake, 2017/06/27
- Re: [Qemu-devel] [RFC 15/15] [test only] Use 'Error *err[static 1]' instead of 'Error **errp' to catch NULL errp arguments, Eduardo Habkost, 2017/06/27
Re: [Qemu-devel] [RFC 00/15] Error API: Flag errors in *errp even if errors are being ignored, Eric Blake, 2017/06/27
Re: [Qemu-devel] [RFC 00/15] Error API: Flag errors in *errp even if errors are being ignored, Markus Armbruster, 2017/06/28