libbacktrace/alloc.c

   1 /* alloc.c -- Memory allocation without mmap.
   2    Copyright (C) 2012-2013 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor, Google.
   4
   5 Redistribution and use in source and binary forms, with or without
   6 modification, are permitted provided that the following conditions are
   7 met:
   8
   9     (1) Redistributions of source code must retain the above copyright
  10     notice, this list of conditions and the following disclaimer.
  11
  12     (2) Redistributions in binary form must reproduce the above copyright
  13     notice, this list of conditions and the following disclaimer in
  14     the documentation and/or other materials provided with the
  15     distribution.
  16
  17     (3) The name of the author may not be used to
  18     endorse or promote products derived from this software without
  19     specific prior written permission.
  20
  21 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  22 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  24 DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  25 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  26 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  27 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  29 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30 IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31 POSSIBILITY OF SUCH DAMAGE.  */
  32
  33 #include "config.h"
  34
  35 #include <errno.h>
  36 #include <stdlib.h>
  37
  38 #include "backtrace.h"
  39 #include "internal.h"
  40
  41 /* Allocation routines to use on systems that do not support anonymous
  42    mmap.  This implementation just uses malloc, which means that the
  43    backtrace functions may not be safely invoked from a signal
  44    handler.  */
  45
  46 /* Allocate memory like malloc.  */
  47
  48 void *
  49 backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED,
  50                  size_t size, backtrace_error_callback error_callback,
  51                  void *data)
  52 {
  53   void *ret;
  54
  55   ret = malloc (size);
  56   if (ret == NULL)
  57     error_callback (data, "malloc", errno);
  58   return ret;
  59 }
  60
  61 /* Free memory.  */
  62
  63 void
  64 backtrace_free (struct backtrace_state *state ATTRIBUTE_UNUSED,
  65                 void *p, size_t size ATTRIBUTE_UNUSED,
  66                 backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
  67                 void *data ATTRIBUTE_UNUSED)
  68 {
  69   free (p);
  70 }
  71
  72 /* Grow VEC by SIZE bytes.  */
  73
  74 void *
  75 backtrace_vector_grow (struct backtrace_state *state ATTRIBUTE_UNUSED,
  76                        size_t size, backtrace_error_callback error_callback,
  77                        void *data, struct backtrace_vector *vec)
  78 {
  79   void *ret;
  80
  81   if (size > vec->alc)
  82     {
  83       size_t alc;
  84       void *base;
  85
  86       if (vec->size == 0)
  87         alc = 32 * size;
  88       else if (vec->size >= 4096)
  89         alc = vec->size + 4096;
  90       else
  91         alc = 2 * vec->size;
  92
  93       if (alc < vec->size + size)
  94         alc = vec->size + size;
  95
  96       base = realloc (vec->base, alc);
  97       if (base == NULL)
  98         {
  99           error_callback (data, "realloc", errno);
 100           return NULL;
 101         }
 102
 103       vec->base = base;
 104       vec->alc = alc - vec->size;
 105     }
 106
 107   ret = (char *) vec->base + vec->size;
 108   vec->size += size;
 109   vec->alc -= size;
 110   return ret;
 111 }
 112
 113 /* Finish the current allocation on VEC.  */
 114
 115 void
 116 backtrace_vector_finish (struct backtrace_state *state ATTRIBUTE_UNUSED,
 117                          struct backtrace_vector *vec)
 118 {
 119   vec->base = (char *) vec->base + vec->size;
 120   vec->size = 0;
 121 }
 122
 123 /* Release any extra space allocated for VEC.  */
 124
 125 int
 126 backtrace_vector_release (struct backtrace_state *state ATTRIBUTE_UNUSED,
 127                           struct backtrace_vector *vec,
 128                           backtrace_error_callback error_callback,
 129                           void *data)
 130 {
 131   vec->base = realloc (vec->base, vec->size);
 132   if (vec->base == NULL)
 133     {
 134       error_callback (data, "realloc", errno);
 135       return 0;
 136     }
 137   vec->alc = 0;
 138   return 1;
 139 }