Re: [libvirt] [PATCH] util: warn when passing a non-pointer to VIR_FREE
On 04/24/2011 04:17 AM, Matthias Bolte wrote:
> So how about:
>
> diff --git i/src/util/memory.h w/src/util/memory.h
> index 66b4c42..d77a295 100644
> --- i/src/util/memory.h
> +++ w/src/util/memory.h
> @@ -1,7 +1,7 @@
> /*
> * memory.c: safer memory allocation
> *
> - * Copyright (C) 2010 Red Hat, Inc.
> + * Copyright (C) 2010-2011 Red Hat, Inc.
> * Copyright (C) 2008 Daniel P. Berrange
> *
> * This library is free software; you can redistribute it and/or
> @@ -197,7 +197,11 @@ void virFree(void *ptrptr) ATTRIBUTE_NONNULL(1);
> * Free the memory stored in 'ptr' and update to point
> * to NULL.
> */
> -# define VIR_FREE(ptr) virFree(&(ptr))
> +/* The ternary ensures that ptr is a pointer and not an integer type,
> + * while evaluating ptr only once. For now, we intentionally cast
> + * away const, since a number of callers safely pass const char *.
> + */
> +# define VIR_FREE(ptr) virFree((void *) (1 ? (const void *) &(ptr) :
> (ptr)))
>
>
> # if TEST_OOM
>
ACK, to your improved version.
Pushed with this commit message:
commit 90d761eeb26c9619571b68a8863b8425a33555d6
Author: Eric Blake <eblake(a)redhat.com>
Date: Fri Apr 22 20:15:50 2011 -0600
build: make VIR_FREE do some type checking
We can exploit the fact that gcc warns about int-to-pointer conversion
in ternary cond?(void*):(int) in order to prevent future mistakes of
calling VIR_FREE on a scalar lvalue. For example, between commits
158ba873 and 802e2df, we would have had this warning:
cc1: warnings being treated as errors
remote.c: In function 'remoteDispatchListNetworks':
remote.c:3684:70: error: pointer/integer type mismatch in
conditional expression
There are still a number of places that malloc into a const char*;
while it would probably be worth scrubbing them to use char*
instead, that is a separate patch, so we have to cast away const
in VIR_FREE for now.
* src/util/memory.h (VIR_FREE): Make gcc warn about integers.
Iteratively developed from a patch by Christophe Fergeau.
--
Eric Blake eblake(a)redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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