libbacktrace/alloc.c

   1 /* alloc.c -- Memory allocation without mmap.
   2    Copyright (C) 2012-2014 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 #include <sys/types.h>
  38
  39 #include "backtrace.h"
  40 #include "internal.h"
  41
  42 /* Allocation routines to use on systems that do not support anonymous
  43    mmap.  This implementation just uses malloc, which means that the
  44    backtrace functions may not be safely invoked from a signal
  45    handler.  */
  46
  47 /* Allocate memory like malloc.  */
  48
  49 void *
  50 backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED,
  51                  size_t size, backtrace_error_callback error_callback,
  52                  void *data)
  53 {
  54   void *ret;
  55
  56   ret = malloc (size);
  57   if (ret == NULL)
  58     error_callback (data, "malloc", errno);
  59   return ret;
  60 }
  61
  62 /* Free memory.  */
  63
  64 void
  65 backtrace_free (struct backtrace_state *state ATTRIBUTE_UNUSED,
  66                 void *p, size_t size ATTRIBUTE_UNUSED,
  67                 backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
  68                 void *data ATTRIBUTE_UNUSED)
  69 {
  70   free (p);
  71 }
  72
  73 /* Grow VEC by SIZE bytes.  */
  74
  75 void *
  76 backtrace_vector_grow (struct backtrace_state *state ATTRIBUTE_UNUSED,
  77                        size_t size, backtrace_error_callback error_callback,
  78                        void *data, struct backtrace_vector *vec)
  79 {
  80   void *ret;
  81
  82   if (size > vec->alc)
  83     {
  84       size_t alc;
  85       void *base;
  86
  87       if (vec->size == 0)
  88         alc = 32 * size;
  89       else if (vec->size >= 4096)
  90         alc = vec->size + 4096;
  91       else
  92         alc = 2 * vec->size;
  93
  94       if (alc < vec->size + size)
  95         alc = vec->size + size;
  96
  97       base = realloc (vec->base, alc);
  98       if (base == NULL)
  99         {
 100           error_callback (data, "realloc", errno);
 101           return NULL;
 102         }
 103
 104       vec->base = base;
 105       vec->alc = alc - vec->size;
 106     }
 107
 108   ret = (char *) vec->base + vec->size;
 109   vec->size += size;
 110   vec->alc -= size;
 111   return ret;
 112 }
 113
 114 /* Finish the current allocation on VEC.  */
 115
 116 void *
 117 backtrace_vector_finish (struct backtrace_state *state,
 118                          struct backtrace_vector *vec,
 119                          backtrace_error_callback error_callback,
 120                          void *data)
 121 {
 122   void *ret;
 123
 124   /* With this allocator we call realloc in backtrace_vector_grow,
 125      which means we can't easily reuse the memory here.  So just
 126      release it.  */
 127   if (!backtrace_vector_release (state, vec, error_callback, data))
 128     return NULL;
 129   ret = vec->base;
 130   vec->base = NULL;
 131   vec->size = 0;
 132   vec->alc = 0;
 133   return ret;
 134 }
 135
 136 /* Release any extra space allocated for VEC.  */
 137
 138 int
 139 backtrace_vector_release (struct backtrace_state *state ATTRIBUTE_UNUSED,
 140                           struct backtrace_vector *vec,
 141                           backtrace_error_callback error_callback,
 142                           void *data)
 143 {
 144   vec->base = realloc (vec->base, vec->size);
 145   if (vec->base == NULL)
 146     {
 147       error_callback (data, "realloc", errno);
 148       return 0;
 149     }
 150   vec->alc = 0;
 151   return 1;
 152 }