src/regex/tre-mem.c

   1 /*
   2   tre-mem.c - TRE memory allocator
   3
   4   Copyright (c) 2001-2009 Ville Laurikari <vl@iki.fi>
   5   All rights reserved.
   6
   7   Redistribution and use in source and binary forms, with or without
   8   modification, are permitted provided that the following conditions
   9   are met:
  10
  11     1. Redistributions of source code must retain the above copyright
  12        notice, this list of conditions and the following disclaimer.
  13
  14     2. Redistributions in binary form must reproduce the above copyright
  15        notice, this list of conditions and the following disclaimer in the
  16        documentation and/or other materials provided with the distribution.
  17
  18   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS
  19   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
  22   HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30 */
  31
  32 /*
  33   This memory allocator is for allocating small memory blocks efficiently
  34   in terms of memory overhead and execution speed.  The allocated blocks
  35   cannot be freed individually, only all at once.  There can be multiple
  36   allocators, though.
  37 */
  38
  39 #include <stdlib.h>
  40 #include <string.h>
  41
  42 #include "tre.h"
  43
  44 /*
  45   This memory allocator is for allocating small memory blocks efficiently
  46   in terms of memory overhead and execution speed.  The allocated blocks
  47   cannot be freed individually, only all at once.  There can be multiple
  48   allocators, though.
  49 */
  50
  51 /* Returns a new memory allocator or NULL if out of memory. */
  52 tre_mem_t
  53 tre_mem_new_impl(int provided, void *provided_block)
  54 {
  55   tre_mem_t mem;
  56   if (provided)
  57     {
  58       mem = provided_block;
  59       memset(mem, 0, sizeof(*mem));
  60     }
  61   else
  62     mem = xcalloc(1, sizeof(*mem));
  63   if (mem == NULL)
  64     return NULL;
  65   return mem;
  66 }
  67
  68
  69 /* Frees the memory allocator and all memory allocated with it. */
  70 void
  71 tre_mem_destroy(tre_mem_t mem)
  72 {
  73   tre_list_t *tmp, *l = mem->blocks;
  74
  75   while (l != NULL)
  76     {
  77       xfree(l->data);
  78       tmp = l->next;
  79       xfree(l);
  80       l = tmp;
  81     }
  82   xfree(mem);
  83 }
  84
  85
  86 /* Allocates a block of `size' bytes from `mem'.  Returns a pointer to the
  87    allocated block or NULL if an underlying malloc() failed. */
  88 void *
  89 tre_mem_alloc_impl(tre_mem_t mem, int provided, void *provided_block,
  90                    int zero, size_t size)
  91 {
  92   void *ptr;
  93
  94   if (mem->failed)
  95     {
  96       return NULL;
  97     }
  98
  99   if (mem->n < size)
 100     {
 101       /* We need more memory than is available in the current block.
 102          Allocate a new block. */
 103       tre_list_t *l;
 104       if (provided)
 105         {
 106           if (provided_block == NULL)
 107             {
 108               mem->failed = 1;
 109               return NULL;
 110             }
 111           mem->ptr = provided_block;
 112           mem->n = TRE_MEM_BLOCK_SIZE;
 113         }
 114       else
 115         {
 116           int block_size;
 117           if (size * 8 > TRE_MEM_BLOCK_SIZE)
 118             block_size = size * 8;
 119           else
 120             block_size = TRE_MEM_BLOCK_SIZE;
 121           l = xmalloc(sizeof(*l));
 122           if (l == NULL)
 123             {
 124               mem->failed = 1;
 125               return NULL;
 126             }
 127           l->data = xmalloc(block_size);
 128           if (l->data == NULL)
 129             {
 130               xfree(l);
 131               mem->failed = 1;
 132               return NULL;
 133             }
 134           l->next = NULL;
 135           if (mem->current != NULL)
 136             mem->current->next = l;
 137           if (mem->blocks == NULL)
 138             mem->blocks = l;
 139           mem->current = l;
 140           mem->ptr = l->data;
 141           mem->n = block_size;
 142         }
 143     }
 144
 145   /* Make sure the next pointer will be aligned. */
 146   size += ALIGN(mem->ptr + size, long);
 147
 148   /* Allocate from current block. */
 149   ptr = mem->ptr;
 150   mem->ptr += size;
 151   mem->n -= size;
 152
 153   /* Set to zero if needed. */
 154   if (zero)
 155     memset(ptr, 0, size);
 156
 157   return ptr;
 158 }