1 /*
2 * Copyright (c) 2012, 2013 ARM Ltd
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the company may not be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
22 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
23 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
24 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
25 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
26 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include "nano-malloc.h"
30
31 /*
32 * Implement either by merging adjacent free memory
33 * or by calling malloc/memcpy
34 */
35 void *
realloc(void * ptr,size_t size)36 realloc(void * ptr, size_t size)
37 {
38 void * mem;
39
40 if (ptr == NULL)
41 return malloc(size);
42
43 if (size == 0)
44 {
45 free(ptr);
46 return NULL;
47 }
48
49 if (size > MALLOC_MAXSIZE)
50 {
51 errno = ENOMEM;
52 return NULL;
53 }
54
55 size_t new_size = chunk_size(size);
56 chunk_t *p_to_realloc = ptr_to_chunk(ptr);
57
58 #if MALLOC_DEBUG
59 __malloc_validate_block(p_to_realloc);
60 #endif
61
62 size_t old_size = _size(p_to_realloc);
63
64 /* See if we can avoid allocating new memory
65 * when increasing the size
66 */
67 if (new_size > old_size)
68 {
69 void *chunk_e = chunk_end(p_to_realloc);
70
71 MALLOC_LOCK;
72
73 if (__malloc_grow_chunk(p_to_realloc, new_size))
74 {
75 /* clear new memory */
76 memset(chunk_e, '\0', new_size - old_size);
77 /* adjust chunk_t size */
78 old_size = new_size;
79 }
80 else
81 {
82 chunk_t **p, *r;
83
84 /* Check to see if there's a chunk_t of free space just past
85 * the current block, merge it in in case that's useful
86 */
87 for (p = &__malloc_free_list; (r = *p) != NULL; p = &r->next)
88 {
89 if (r == chunk_e)
90 {
91 size_t r_size = _size(r);
92
93 /* remove R from the free list */
94 *p = r->next;
95
96 /* clear the memory from r */
97 memset(r, '\0', r_size);
98
99 /* add it's size to our block */
100 old_size += r_size;
101 _set_size(p_to_realloc, old_size);
102 break;
103 }
104 if (p_to_realloc < r)
105 break;
106 }
107 }
108
109 MALLOC_UNLOCK;
110 }
111
112 if (new_size <= old_size)
113 {
114 size_t extra = old_size - new_size;
115
116 /* If there's enough space left over, split it out
117 * and free it
118 */
119 if (extra >= MALLOC_MINSIZE) {
120 _set_size(p_to_realloc, new_size);
121 make_free_chunk(chunk_after(p_to_realloc), extra);
122 }
123 return ptr;
124 }
125
126 /* No short cuts, allocate new memory and copy */
127
128 mem = malloc(size);
129 if (!mem)
130 return NULL;
131
132 memcpy(mem, ptr, old_size - MALLOC_HEAD);
133 free(ptr);
134
135 return mem;
136 }
137
