lavu: add a new API for reference-counted data buffers.
[libav.git] / libavutil / buffer.c
1 /*
2 * This file is part of Libav.
3 *
4 * Libav is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * Libav is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with Libav; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #include <stdint.h>
20 #include <string.h>
21
22 #include "atomic.h"
23 #include "buffer_internal.h"
24 #include "common.h"
25 #include "mem.h"
26
27 AVBufferRef *av_buffer_create(uint8_t *data, int size,
28 void (*free)(void *opaque, uint8_t *data),
29 void *opaque, int flags)
30 {
31 AVBufferRef *ref = NULL;
32 AVBuffer *buf = NULL;
33
34 buf = av_mallocz(sizeof(*buf));
35 if (!buf)
36 return NULL;
37
38 buf->data = data;
39 buf->size = size;
40 buf->free = free ? free : av_buffer_default_free;
41 buf->opaque = opaque;
42 buf->refcount = 1;
43
44 if (flags & AV_BUFFER_FLAG_READONLY)
45 buf->flags |= BUFFER_FLAG_READONLY;
46
47 ref = av_mallocz(sizeof(*ref));
48 if (!ref) {
49 av_freep(&buf);
50 return NULL;
51 }
52
53 ref->buffer = buf;
54 ref->data = data;
55 ref->size = size;
56
57 return ref;
58 }
59
60 void av_buffer_default_free(void *opaque, uint8_t *data)
61 {
62 av_free(data);
63 }
64
65 AVBufferRef *av_buffer_alloc(int size)
66 {
67 AVBufferRef *ret = NULL;
68 uint8_t *data = NULL;
69
70 data = av_malloc(size);
71 if (!data)
72 return NULL;
73
74 ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
75 if (!ret)
76 av_freep(&data);
77
78 return ret;
79 }
80
81 AVBufferRef *av_buffer_allocz(int size)
82 {
83 AVBufferRef *ret = av_buffer_alloc(size);
84 if (!ret)
85 return NULL;
86
87 memset(ret->data, 0, size);
88 return ret;
89 }
90
91 AVBufferRef *av_buffer_ref(AVBufferRef *buf)
92 {
93 AVBufferRef *ret = av_mallocz(sizeof(*ret));
94
95 if (!ret)
96 return NULL;
97
98 *ret = *buf;
99
100 avpriv_atomic_int_add_and_fetch(&buf->buffer->refcount, 1);
101
102 return ret;
103 }
104
105 void av_buffer_unref(AVBufferRef **buf)
106 {
107 AVBuffer *b;
108
109 if (!buf || !*buf)
110 return;
111 b = (*buf)->buffer;
112 av_freep(buf);
113
114 if (!avpriv_atomic_int_add_and_fetch(&b->refcount, -1)) {
115 b->free(b->opaque, b->data);
116 av_freep(&b);
117 }
118 }
119
120 int av_buffer_is_writable(const AVBufferRef *buf)
121 {
122 if (buf->buffer->flags & AV_BUFFER_FLAG_READONLY)
123 return 0;
124
125 return avpriv_atomic_int_add_and_fetch(&buf->buffer->refcount, 0) == 1;
126 }
127
128 int av_buffer_make_writable(AVBufferRef **pbuf)
129 {
130 AVBufferRef *newbuf, *buf = *pbuf;
131
132 if (av_buffer_is_writable(buf))
133 return 0;
134
135 newbuf = av_buffer_alloc(buf->size);
136 if (!newbuf)
137 return AVERROR(ENOMEM);
138
139 memcpy(newbuf->data, buf->data, buf->size);
140 av_buffer_unref(pbuf);
141 *pbuf = newbuf;
142
143 return 0;
144 }
145
146 int av_buffer_realloc(AVBufferRef **pbuf, int size)
147 {
148 AVBufferRef *buf = *pbuf;
149 uint8_t *tmp;
150
151 if (!buf) {
152 /* allocate a new buffer with av_realloc(), so it will be reallocatable
153 * later */
154 uint8_t *data = av_realloc(NULL, size);
155 if (!data)
156 return AVERROR(ENOMEM);
157
158 buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
159 if (!buf) {
160 av_freep(&data);
161 return AVERROR(ENOMEM);
162 }
163
164 buf->buffer->flags |= BUFFER_FLAG_REALLOCATABLE;
165 *pbuf = buf;
166
167 return 0;
168 } else if (buf->size == size)
169 return 0;
170
171 if (!(buf->buffer->flags & BUFFER_FLAG_REALLOCATABLE) ||
172 !av_buffer_is_writable(buf)) {
173 /* cannot realloc, allocate a new reallocable buffer and copy data */
174 AVBufferRef *new = NULL;
175
176 av_buffer_realloc(&new, size);
177 if (!new)
178 return AVERROR(ENOMEM);
179
180 memcpy(new->data, buf->data, FFMIN(size, buf->size));
181
182 av_buffer_unref(pbuf);
183 *pbuf = new;
184 return 0;
185 }
186
187 tmp = av_realloc(buf->buffer->data, size);
188 if (!tmp)
189 return AVERROR(ENOMEM);
190
191 buf->buffer->data = buf->data = tmp;
192 buf->buffer->size = buf->size = size;
193 return 0;
194 }