lib/util/memory.h

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba utility functions
   4    Copyright (C) Andrew Tridgell 1992-1999
   5    Copyright (C) Jelmer Vernooij <jelmer@samba.org> 2008
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #ifndef _SAMBA_MEMORY_H_
  22 #define _SAMBA_MEMORY_H_
  23
  24 #ifndef SAFE_FREE /* Oh no this is also defined in tdb.h */
  25 /**
  26  * Free memory if the pointer and zero the pointer.
  27  *
  28  * @note You are explicitly allowed to pass NULL pointers -- they will
  29  * always be ignored.
  30  **/
  31 #define SAFE_FREE(x) do { if ((x) != NULL) {free(discard_const_p(void *, (x))); (x)=NULL;} } while(0)
  32 #endif
  33
  34 /**
  35  * Type-safe version of malloc. Allocated one copy of the
  36  * specified data type.
  37  */
  38 #define malloc_p(type) (type *)malloc(sizeof(type))
  39
  40 /**
  41  * Allocate an array of elements of one data type. Does type-checking.
  42  */
  43 #define malloc_array_p(type, count) (type *)realloc_array(NULL, sizeof(type), count, false)
  44
  45 /**
  46  * Resize an array of elements of one data type. Does type-checking.
  47  */
  48 #define realloc_p(p, type, count) (type *)realloc_array(p, sizeof(type), count, false)
  49
  50 /**
  51  * zero a structure
  52  */
  53 #ifndef ZERO_STRUCT
  54 #define ZERO_STRUCT(x) memset((char *)&(x), 0, sizeof(x))
  55 #endif
  56
  57 /**
  58  * zero a structure given a pointer to the structure
  59  */
  60 #ifndef ZERO_STRUCTP
  61 #define ZERO_STRUCTP(x) do { if ((x) != NULL) memset((char *)(x), 0, sizeof(*(x))); } while(0)
  62 #endif
  63
  64 /**
  65  * zero a structure given a pointer to the structure - no zero check
  66  */
  67 #ifndef ZERO_STRUCTPN
  68 #define ZERO_STRUCTPN(x) memset((char *)(x), 0, sizeof(*(x)))
  69 #endif
  70
  71 /* zero an array - note that sizeof(array) must work - ie. it must not be a
  72    pointer */
  73 #ifndef ZERO_ARRAY
  74 #define ZERO_ARRAY(x) memset((char *)(x), 0, sizeof(x))
  75 #endif
  76
  77 /**
  78  * work out how many elements there are in a static array
  79  */
  80 #ifndef ARRAY_SIZE
  81 #define ARRAY_SIZE(a) (sizeof(a)/sizeof(a[0]))
  82 #endif
  83
  84 /**
  85  * pointer difference macro
  86  */
  87 #ifndef PTR_DIFF
  88 #define PTR_DIFF(p1,p2) ((ptrdiff_t)(((const char *)(p1)) - (const char *)(p2)))
  89 #endif
  90
  91 /**
  92   this is a warning hack. The idea is to use this everywhere that we
  93   get the "discarding const" warning from gcc. That doesn't actually
  94   fix the problem of course, but it means that when we do get to
  95   cleaning them up we can do it by searching the code for
  96   discard_const.
  97
  98   It also means that other error types aren't as swamped by the noise
  99   of hundreds of const warnings, so we are more likely to notice when
 100   we get new errors.
 101
 102   Please only add more uses of this macro when you find it
 103   _really_ hard to fix const warnings. Our aim is to eventually use
 104   this function in only a very few places.
 105
 106   Also, please call this via the discard_const_p() macro interface, as that
 107   makes the return type safe.
 108 */
 109 #ifndef discard_const
 110 #define discard_const(ptr) ((void *)((uintptr_t)(ptr)))
 111 #endif
 112
 113 /** Type-safe version of discard_const */
 114 #ifndef discard_const_p
 115 #define discard_const_p(type, ptr) ((type *)discard_const(ptr))
 116 #endif
 117
 118 #endif /* _SAMBA_MEMORY_H_ */