OSX/utilities/SecCFRelease.h

   1 /*
   2  * Copyright (c) 2012,2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  18  * Please see the License for the specific language governing rights and
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  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 #ifndef _SECCFRELEASE_H_
  26 #define _SECCFRELEASE_H_
  27
  28 #include <CoreFoundation/CFBase.h>
  29
  30 // Retains its argument unless it's NULL.  Always returns its argument.
  31 #define CFRetainSafe(CF) ({ __typeof__(CF) _cf = (CF); _cf ? (CFRetain(_cf), _cf) : _cf; })
  32
  33 // Releases CF unless it's NULL.  Always returns NULL, for your convenience and constructs like:
  34 // return CFReleaseSafe(foo);
  35 #define CFReleaseSafe(CF) ({ __typeof__(CF) _cf = (CF); (_cf ? (CFRelease(_cf), ((__typeof__(CF))0)) : _cf); })
  36
  37
  38 #if 0
  39 // Objective-C defines &<bridged-object> to be a constant reference, which we can't assign to, so we
  40 // suffer multiple evaluations of arguments (avoid using it with side-effects) to make things compile well
  41
  42 #define CFTransferRetained(VAR1, VAR2) ({ CFReleaseSafe(VAR1); VAR1 = VAR2; VAR2 = ((__typeof__(VAR2))0)); })
  43
  44 #define CFAssignRetained(VAR, CF) ({ CFReleaseSafe(VAR); VAR1 = CF; CF = ((__typeof__(CF))0)); })
  45
  46 #define CFRetainAssign(VAR,CF) ({ CFReleaseSafe(VAR); VAR = CFRetainSafe(CF); })
  47
  48 #define CFReleaseNull(CF) ({ CFReleaseSafe(CF); CF = ((__typeof__(CF))0)); })
  49
  50 #else
  51
  52 // Assume VAR1 is NULL or an already retained object and CFReleaseSafe VAR1 and assigns VAR2 to VAR1. Returns VAR2.
  53 #define CFTransferRetained(VAR1, VAR2) ({ \
  54     __typeof__(VAR1) *const _pvar1 = &(VAR1); \
  55     __typeof__(VAR2) *const _pvar2 = &(VAR2); \
  56     __typeof__(VAR2) _var2 = *_pvar2; \
  57     (*_pvar2) = NULL; \
  58     (*_pvar1) = *_pvar1 ? (CFRelease(*_pvar1), _var2) : _var2; \
  59 })
  60
  61
  62 // Assume CF is NULL or an already retained object and CFReleaseSafe VAR and assigns CF to VAR. Returns CF.
  63 #define CFAssignRetained(VAR,CF) ({ \
  64     __typeof__(VAR) *const _pvar = &(VAR); \
  65     __typeof__(CF) _cf = (CF); \
  66     (*_pvar) = *_pvar ? (CFRelease(*_pvar), _cf) : _cf; \
  67 })
  68
  69 // CFRetainSafe CF and CFReleaseSafe VAR and assigns CF to VAR. Returns CF.
  70 #define CFRetainAssign(VAR,CF) ({ \
  71     __typeof__(VAR) *const _pvar = &(VAR); \
  72     __typeof__(CF) _cf = (CF); \
  73     (((*_pvar) == _cf) ? _cf \
  74     : ((*_pvar) = (_cf ? (CFRetain(_cf), (*_pvar ? (CFRelease(*_pvar), _cf) : _cf)) \
  75                    : (CFRelease(*_pvar), ((__typeof__(_cf))0))))); \
  76 })
  77
  78
  79 // Assigns NULL to CF. Releases the value stored at CF unless it was NULL.  Always returns NULL, for your convenience
  80 #define CFReleaseNull(CF) ({ __typeof__(CF) *const _pcf = &(CF), _cf = *_pcf; (_cf ? (*_pcf) = ((__typeof__(CF))0), (CFRelease(_cf), ((__typeof__(CF))0)) : _cf); })
  81
  82 #endif
  83
  84 #endif /* _SECCFRELEASE_H_ */