SecCFRelease.h   [plain text]

/*
 * Copyright (c) 2012,2014 Apple Inc. All Rights Reserved.
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 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
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 */


#ifndef _SECCFRELEASE_H_
#define _SECCFRELEASE_H_

#include <CoreFoundation/CFBase.h>

// Retains its argument unless it's NULL.  Always returns its argument.
#define CFRetainSafe(CF) ({ __typeof__(CF) _cf = (CF); _cf ? (CFRetain(_cf), _cf) : _cf; })

// Releases CF unless it's NULL.  Always returns NULL, for your convenience and constructs like:
// return CFReleaseSafe(foo);
#define CFReleaseSafe(CF) ({ __typeof__(CF) _cf = (CF); (_cf ? (CFRelease(_cf), ((__typeof__(CF))0)) : _cf); })


#if 0
// Objective-C defines &<bridged-object> to be a constant reference, which we can't assign to, so we
// suffer multiple evaluations of arguments (avoid using it with side-effects) to make things compile well

#define CFTransferRetained(VAR1, VAR2) ({ CFReleaseSafe(VAR1); VAR1 = VAR2; VAR2 = ((__typeof__(VAR2))0)); })

#define CFAssignRetained(VAR, CF) ({ CFReleaseSafe(VAR); VAR1 = CF; CF = ((__typeof__(CF))0)); })

#define CFRetainAssign(VAR,CF) ({ CFReleaseSafe(VAR); VAR = CFRetainSafe(CF); })

#define CFReleaseNull(CF) ({ CFReleaseSafe(CF); CF = ((__typeof__(CF))0)); })

#else

// Assume VAR1 is NULL or an already retained object and CFReleaseSafe VAR1 and assigns VAR2 to VAR1. Returns VAR2.
#define CFTransferRetained(VAR1, VAR2) ({ \
    __typeof__(VAR1) *const _pvar1 = &(VAR1); \
    __typeof__(VAR2) *const _pvar2 = &(VAR2); \
    __typeof__(VAR2) _var2 = *_pvar2; \
    (*_pvar2) = NULL; \
    (*_pvar1) = *_pvar1 ? (CFRelease(*_pvar1), _var2) : _var2; \
})


// Assume CF is NULL or an already retained object and CFReleaseSafe VAR and assigns CF to VAR. Returns CF.
#define CFAssignRetained(VAR,CF) ({ \
    __typeof__(VAR) *const _pvar = &(VAR); \
    __typeof__(CF) _cf = (CF); \
    (*_pvar) = *_pvar ? (CFRelease(*_pvar), _cf) : _cf; \
})

// CFRetainSafe CF and CFReleaseSafe VAR and assigns CF to VAR. Returns CF.
#define CFRetainAssign(VAR,CF) ({ \
    __typeof__(VAR) *const _pvar = &(VAR); \
    __typeof__(CF) _cf = (CF); \
    (((*_pvar) == _cf) ? _cf \
    : ((*_pvar) = (_cf ? (CFRetain(_cf), (*_pvar ? (CFRelease(*_pvar), _cf) : _cf)) \
                   : (CFRelease(*_pvar), ((__typeof__(_cf))0))))); \
})


// Assigns NULL to CF. Releases the value stored at CF unless it was NULL.  Always returns NULL, for your convenience
#define CFReleaseNull(CF) ({ __typeof__(CF) *const _pcf = &(CF), _cf = *_pcf; (_cf ? (*_pcf) = ((__typeof__(CF))0), (CFRelease(_cf), ((__typeof__(CF))0)) : _cf); })

#endif

#endif /* _SECCFRELEASE_H_ */