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alloc.c revision 1.1.1.1 
      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 #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 }
    153