1/* alloc.c -- Memory allocation without mmap.
2   Copyright (C) 2012-2020 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.  If ERROR_CALLBACK is NULL, don't
48   report an error.  */
49
50void *
51backtrace_alloc (struct backtrace_state *state ATTRIBUTE_UNUSED,
52		 size_t size, backtrace_error_callback error_callback,
53		 void *data)
54{
55  void *ret;
56
57  ret = malloc (size);
58  if (ret == NULL)
59    {
60      if (error_callback)
61	error_callback (data, "malloc", errno);
62    }
63  return ret;
64}
65
66/* Free memory.  */
67
68void
69backtrace_free (struct backtrace_state *state ATTRIBUTE_UNUSED,
70		void *p, size_t size ATTRIBUTE_UNUSED,
71		backtrace_error_callback error_callback ATTRIBUTE_UNUSED,
72		void *data ATTRIBUTE_UNUSED)
73{
74  free (p);
75}
76
77/* Grow VEC by SIZE bytes.  */
78
79void *
80backtrace_vector_grow (struct backtrace_state *state ATTRIBUTE_UNUSED,
81		       size_t size, backtrace_error_callback error_callback,
82		       void *data, struct backtrace_vector *vec)
83{
84  void *ret;
85
86  if (size > vec->alc)
87    {
88      size_t alc;
89      void *base;
90
91      if (vec->size == 0)
92	alc = 32 * size;
93      else if (vec->size >= 4096)
94	alc = vec->size + 4096;
95      else
96	alc = 2 * vec->size;
97
98      if (alc < vec->size + size)
99	alc = vec->size + size;
100
101      base = realloc (vec->base, alc);
102      if (base == NULL)
103	{
104	  error_callback (data, "realloc", errno);
105	  return NULL;
106	}
107
108      vec->base = base;
109      vec->alc = alc - vec->size;
110    }
111
112  ret = (char *) vec->base + vec->size;
113  vec->size += size;
114  vec->alc -= size;
115  return ret;
116}
117
118/* Finish the current allocation on VEC.  */
119
120void *
121backtrace_vector_finish (struct backtrace_state *state,
122			 struct backtrace_vector *vec,
123			 backtrace_error_callback error_callback,
124			 void *data)
125{
126  void *ret;
127
128  /* With this allocator we call realloc in backtrace_vector_grow,
129     which means we can't easily reuse the memory here.  So just
130     release it.  */
131  if (!backtrace_vector_release (state, vec, error_callback, data))
132    return NULL;
133  ret = vec->base;
134  vec->base = NULL;
135  vec->size = 0;
136  vec->alc = 0;
137  return ret;
138}
139
140/* Release any extra space allocated for VEC.  */
141
142int
143backtrace_vector_release (struct backtrace_state *state ATTRIBUTE_UNUSED,
144			  struct backtrace_vector *vec,
145			  backtrace_error_callback error_callback,
146			  void *data)
147{
148  vec->alc = 0;
149
150  if (vec->size == 0)
151    {
152      /* As of C17, realloc with size 0 is marked as an obsolescent feature, use
153	 free instead.  */
154      free (vec->base);
155      vec->base = NULL;
156      return 1;
157    }
158
159  vec->base = realloc (vec->base, vec->size);
160  if (vec->base == NULL)
161    {
162      error_callback (data, "realloc", errno);
163      return 0;
164    }
165
166  return 1;
167}
168