source/lib/talloc.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 3.0
   4    Samba temporary memory allocation functions
   5    Copyright (C) Andrew Tridgell 2000
   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 2 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, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /* this is a very simple temporary memory allocator. To use it do the following:
  23
  24    1) when you first want to allocate a pool of meomry use
  25    talloc_init() and save the resulting context pointer somewhere
  26
  27    2) to allocate memory use talloc()
  28
  29    3) when _all_ of the memory allocated using this context is no longer needed
  30    use talloc_destroy()
  31
  32    talloc does not zero the memory. It guarantees memory of a
  33    TALLOC_ALIGN alignment
  34 */
  35
  36 #include "includes.h"
  37
  38 /* initialissa talloc context. */
  39 TALLOC_CTX *talloc_init(void)
  40 {
  41         TALLOC_CTX *t;
  42
  43         t = (TALLOC_CTX *)malloc(sizeof(*t));
  44         if (!t) return NULL;
  45
  46         t->list = NULL;
  47         t->total_alloc_size = 0;
  48
  49         return t;
  50 }
  51
  52 /* allocate a bit of memory from the specified pool */
  53 void *talloc(TALLOC_CTX *t, size_t size)
  54 {
  55         void *p;
  56         struct talloc_chunk *tc;
  57
  58         if (size == 0) {
  59                 /* debugging value used to track down
  60                    memory problems. BAD_PTR is defined
  61                    in talloc.h */
  62                 p = BAD_PTR;
  63                 return p;
  64         }
  65
  66         p = malloc(size);
  67         if (!p) return p;
  68
  69         tc = malloc(sizeof(*tc));
  70         if (!tc) {
  71                 free(p);
  72                 return NULL;
  73         }
  74
  75         tc->ptr = p;
  76         tc->size = size;
  77         tc->next = t->list;
  78         t->list = tc;
  79         t->total_alloc_size += size;
  80
  81         return p;
  82 }
  83
  84 /* a talloc version of realloc */
  85 void *talloc_realloc(TALLOC_CTX *t, void *ptr, size_t size)
  86 {
  87         struct talloc_chunk *tc;
  88
  89         for (tc=t->list; tc; tc=tc->next) {
  90                 if (tc->ptr == ptr) {
  91                         ptr = realloc(ptr, size);
  92                         if (ptr) {
  93                                 t->total_alloc_size += (size - tc->size);
  94                                 tc->size = size;
  95                                 tc->ptr = ptr;
  96                         }
  97                         return ptr;
  98                 }
  99         }
 100         return NULL;
 101 }
 102
 103 /* destroy a whole pool */
 104 void talloc_destroy_pool(TALLOC_CTX *t)
 105 {
 106         struct talloc_chunk *c;
 107
 108         if (!t)
 109                 return;
 110
 111         while (t->list) {
 112                 c = t->list->next;
 113                 if (t->list->ptr) free(t->list->ptr);
 114                 free(t->list);
 115                 t->list = c;
 116         }
 117
 118         t->list = NULL;
 119         t->total_alloc_size = 0;
 120 }
 121
 122 /* destroy a whole pool including the context */
 123 void talloc_destroy(TALLOC_CTX *t)
 124 {
 125         if (!t)
 126                 return;
 127         talloc_destroy_pool(t);
 128         memset(t, 0, sizeof(*t));
 129         free(t);
 130 }
 131
 132 /* return the current total size of the pool. */
 133 size_t talloc_pool_size(TALLOC_CTX *t)
 134 {
 135         return t->total_alloc_size;
 136 }
 137
 138 /* talloc and zero memory. */
 139 void *talloc_zero(TALLOC_CTX *t, size_t size)
 140 {
 141         void *p = talloc(t, size);
 142
 143         if (p)
 144                 memset(p, '\0', size);
 145
 146         return p;
 147 }
 148
 149 /* memdup with a talloc. */
 150 void *talloc_memdup(TALLOC_CTX *t, void *p, size_t size)
 151 {
 152         void *newp = talloc(t,size);
 153
 154         if (!newp)
 155                 return 0;
 156
 157         memcpy(newp, p, size);
 158
 159         return newp;
 160 }