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 /* initialise 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) return NULL;
  59
  60         p = malloc(size);
  61         if (!p) return p;
  62
  63         tc = malloc(sizeof(*tc));
  64         if (!tc) {
  65                 SAFE_FREE(p);
  66                 return NULL;
  67         }
  68
  69         tc->ptr = p;
  70         tc->size = size;
  71         tc->next = t->list;
  72         t->list = tc;
  73         t->total_alloc_size += size;
  74
  75         return p;
  76 }
  77
  78 /* a talloc version of realloc */
  79 void *talloc_realloc(TALLOC_CTX *t, void *ptr, size_t size)
  80 {
  81         struct talloc_chunk *tc;
  82         void *new_ptr;
  83
  84         /* size zero is equivalent to free() */
  85         if (size == 0)
  86                 return NULL;
  87
  88         /* realloc(NULL) is equavalent to malloc() */
  89         if (ptr == NULL)
  90                 return talloc(t, size);
  91
  92         for (tc=t->list; tc; tc=tc->next) {
  93                 if (tc->ptr == ptr) {
  94                         new_ptr = Realloc(ptr, size);
  95                         if (new_ptr) {
  96                                 t->total_alloc_size += (size - tc->size);
  97                                 tc->size = size;
  98                                 tc->ptr = new_ptr;
  99                         }
 100                         return new_ptr;
 101                 }
 102         }
 103         return NULL;
 104 }
 105
 106 /* destroy a whole pool */
 107 void talloc_destroy_pool(TALLOC_CTX *t)
 108 {
 109         struct talloc_chunk *c;
 110
 111         if (!t)
 112                 return;
 113
 114         while (t->list) {
 115                 c = t->list->next;
 116                 SAFE_FREE(t->list->ptr);
 117                 SAFE_FREE(t->list);
 118                 t->list = c;
 119         }
 120
 121         t->list = NULL;
 122         t->total_alloc_size = 0;
 123 }
 124
 125 /* destroy a whole pool including the context */
 126 void talloc_destroy(TALLOC_CTX *t)
 127 {
 128         if (!t)
 129                 return;
 130         talloc_destroy_pool(t);
 131         memset(t, 0, sizeof(*t));
 132         SAFE_FREE(t);
 133 }
 134
 135 /* return the current total size of the pool. */
 136 size_t talloc_pool_size(TALLOC_CTX *t)
 137 {
 138         return t->total_alloc_size;
 139 }
 140
 141 /* talloc and zero memory. */
 142 void *talloc_zero(TALLOC_CTX *t, size_t size)
 143 {
 144         void *p = talloc(t, size);
 145
 146         if (p)
 147                 memset(p, '\0', size);
 148
 149         return p;
 150 }
 151
 152 /* memdup with a talloc. */
 153 void *talloc_memdup(TALLOC_CTX *t, void *p, size_t size)
 154 {
 155         void *newp = talloc(t,size);
 156
 157         if (!newp)
 158                 return 0;
 159
 160         memcpy(newp, p, size);
 161
 162         return newp;
 163 }
 164
 165 /* strdup with a talloc */
 166 char *talloc_strdup(TALLOC_CTX *t, char *p)
 167 {
 168         return talloc_memdup(t, p, strlen(p) + 1);
 169 }