1/* alloc.c -- Memory allocation without mmap.
2   Copyright (C) 2012-2015 Free Software Foundation, Inc.
3   Written by Ian Lance Taylor, Google.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are
7met:
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
21THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
25INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
26(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
27SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
29STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31POSSIBILITY 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
49void *
50backtrace_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
64void
65backtrace_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
75void *
76backtrace_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
116void *
117backtrace_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
138int
139backtrace_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