buffer.c 8.34 KB
Newer Older
1
/*
2
 * This file is part of FFmpeg.
3
 *
4
 * FFmpeg is free software; you can redistribute it and/or
5 6 7 8
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
9
 * FFmpeg is distributed in the hope that it will be useful,
10 11 12 13 14
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
15
 * License along with FFmpeg; if not, write to the Free Software
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdint.h>
#include <string.h>

#include "atomic.h"
#include "buffer_internal.h"
#include "common.h"
#include "mem.h"

AVBufferRef *av_buffer_create(uint8_t *data, int size,
                              void (*free)(void *opaque, uint8_t *data),
                              void *opaque, int flags)
{
    AVBufferRef *ref = NULL;
    AVBuffer    *buf = NULL;

    buf = av_mallocz(sizeof(*buf));
    if (!buf)
        return NULL;

    buf->data     = data;
    buf->size     = size;
    buf->free     = free ? free : av_buffer_default_free;
    buf->opaque   = opaque;
    buf->refcount = 1;

    if (flags & AV_BUFFER_FLAG_READONLY)
        buf->flags |= BUFFER_FLAG_READONLY;

    ref = av_mallocz(sizeof(*ref));
    if (!ref) {
        av_freep(&buf);
        return NULL;
    }

    ref->buffer = buf;
    ref->data   = data;
    ref->size   = size;

    return ref;
}

void av_buffer_default_free(void *opaque, uint8_t *data)
{
    av_free(data);
}

AVBufferRef *av_buffer_alloc(int size)
{
    AVBufferRef *ret = NULL;
    uint8_t    *data = NULL;

    data = av_malloc(size);
    if (!data)
        return NULL;

    ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
    if (!ret)
        av_freep(&data);

    return ret;
}

AVBufferRef *av_buffer_allocz(int size)
{
    AVBufferRef *ret = av_buffer_alloc(size);
    if (!ret)
        return NULL;

    memset(ret->data, 0, size);
    return ret;
}

AVBufferRef *av_buffer_ref(AVBufferRef *buf)
{
    AVBufferRef *ret = av_mallocz(sizeof(*ret));

    if (!ret)
        return NULL;

    *ret = *buf;

    avpriv_atomic_int_add_and_fetch(&buf->buffer->refcount, 1);

    return ret;
}

void av_buffer_unref(AVBufferRef **buf)
{
    AVBuffer *b;

    if (!buf || !*buf)
        return;
    b = (*buf)->buffer;
    av_freep(buf);

    if (!avpriv_atomic_int_add_and_fetch(&b->refcount, -1)) {
        b->free(b->opaque, b->data);
        av_freep(&b);
    }
}

int av_buffer_is_writable(const AVBufferRef *buf)
{
    if (buf->buffer->flags & AV_BUFFER_FLAG_READONLY)
        return 0;

125
    return avpriv_atomic_int_get(&buf->buffer->refcount) == 1;
126 127
}

128 129 130 131 132
void *av_buffer_get_opaque(const AVBufferRef *buf)
{
    return buf->buffer->opaque;
}

133 134 135 136 137
int av_buffer_get_ref_count(const AVBufferRef *buf)
{
    return buf->buffer->refcount;
}

138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204
int av_buffer_make_writable(AVBufferRef **pbuf)
{
    AVBufferRef *newbuf, *buf = *pbuf;

    if (av_buffer_is_writable(buf))
        return 0;

    newbuf = av_buffer_alloc(buf->size);
    if (!newbuf)
        return AVERROR(ENOMEM);

    memcpy(newbuf->data, buf->data, buf->size);
    av_buffer_unref(pbuf);
    *pbuf = newbuf;

    return 0;
}

int av_buffer_realloc(AVBufferRef **pbuf, int size)
{
    AVBufferRef *buf = *pbuf;
    uint8_t *tmp;

    if (!buf) {
        /* allocate a new buffer with av_realloc(), so it will be reallocatable
         * later */
        uint8_t *data = av_realloc(NULL, size);
        if (!data)
            return AVERROR(ENOMEM);

        buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
        if (!buf) {
            av_freep(&data);
            return AVERROR(ENOMEM);
        }

        buf->buffer->flags |= BUFFER_FLAG_REALLOCATABLE;
        *pbuf = buf;

        return 0;
    } else if (buf->size == size)
        return 0;

    if (!(buf->buffer->flags & BUFFER_FLAG_REALLOCATABLE) ||
        !av_buffer_is_writable(buf)) {
        /* cannot realloc, allocate a new reallocable buffer and copy data */
        AVBufferRef *new = NULL;

        av_buffer_realloc(&new, size);
        if (!new)
            return AVERROR(ENOMEM);

        memcpy(new->data, buf->data, FFMIN(size, buf->size));

        av_buffer_unref(pbuf);
        *pbuf = new;
        return 0;
    }

    tmp = av_realloc(buf->buffer->data, size);
    if (!tmp)
        return AVERROR(ENOMEM);

    buf->buffer->data = buf->data = tmp;
    buf->buffer->size = buf->size = size;
    return 0;
}
205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251

AVBufferPool *av_buffer_pool_init(int size, AVBufferRef* (*alloc)(int size))
{
    AVBufferPool *pool = av_mallocz(sizeof(*pool));
    if (!pool)
        return NULL;

    pool->size     = size;
    pool->alloc    = alloc ? alloc : av_buffer_alloc;

    avpriv_atomic_int_set(&pool->refcount, 1);

    return pool;
}

/*
 * This function gets called when the pool has been uninited and
 * all the buffers returned to it.
 */
static void buffer_pool_free(AVBufferPool *pool)
{
    while (pool->pool) {
        BufferPoolEntry *buf = pool->pool;
        pool->pool = buf->next;

        buf->free(buf->opaque, buf->data);
        av_freep(&buf);
    }
    av_freep(&pool);
}

void av_buffer_pool_uninit(AVBufferPool **ppool)
{
    AVBufferPool *pool;

    if (!ppool || !*ppool)
        return;
    pool   = *ppool;
    *ppool = NULL;

    if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
        buffer_pool_free(pool);
}

/* remove the whole buffer list from the pool and return it */
static BufferPoolEntry *get_pool(AVBufferPool *pool)
{
252
    BufferPoolEntry *cur = *(void * volatile *)&pool->pool, *last = NULL;
253

254
    while (cur != last) {
255
        last = cur;
256 257 258
        cur = avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, last, NULL);
        if (!cur)
            return NULL;
259
    }
260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275

    return cur;
}

static void add_to_pool(BufferPoolEntry *buf)
{
    AVBufferPool *pool;
    BufferPoolEntry *cur, *end = buf;

    if (!buf)
        return;
    pool = buf->pool;

    while (end->next)
        end = end->next;

276
    while (avpriv_atomic_ptr_cas((void * volatile *)&pool->pool, NULL, buf)) {
277 278 279 280 281 282 283 284 285 286 287 288
        /* pool is not empty, retrieve it and append it to our list */
        cur = get_pool(pool);
        end->next = cur;
        while (end->next)
            end = end->next;
    }
}

static void pool_release_buffer(void *opaque, uint8_t *data)
{
    BufferPoolEntry *buf = opaque;
    AVBufferPool *pool = buf->pool;
289 290

    if(CONFIG_MEMORY_POISONING)
291
        memset(buf->data, FF_MEMORY_POISON, pool->size);
292

293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323
    add_to_pool(buf);
    if (!avpriv_atomic_int_add_and_fetch(&pool->refcount, -1))
        buffer_pool_free(pool);
}

/* allocate a new buffer and override its free() callback so that
 * it is returned to the pool on free */
static AVBufferRef *pool_alloc_buffer(AVBufferPool *pool)
{
    BufferPoolEntry *buf;
    AVBufferRef     *ret;

    ret = pool->alloc(pool->size);
    if (!ret)
        return NULL;

    buf = av_mallocz(sizeof(*buf));
    if (!buf) {
        av_buffer_unref(&ret);
        return NULL;
    }

    buf->data   = ret->buffer->data;
    buf->opaque = ret->buffer->opaque;
    buf->free   = ret->buffer->free;
    buf->pool   = pool;

    ret->buffer->opaque = buf;
    ret->buffer->free   = pool_release_buffer;

    avpriv_atomic_int_add_and_fetch(&pool->refcount, 1);
324
    avpriv_atomic_int_add_and_fetch(&pool->nb_allocated, 1);
325 326 327 328 329 330 331 332 333 334 335

    return ret;
}

AVBufferRef *av_buffer_pool_get(AVBufferPool *pool)
{
    AVBufferRef *ret;
    BufferPoolEntry *buf;

    /* check whether the pool is empty */
    buf = get_pool(pool);
336 337 338 339 340 341
    if (!buf && pool->refcount <= pool->nb_allocated) {
        av_log(NULL, AV_LOG_DEBUG, "Pool race dectected, spining to avoid overallocation and eventual OOM\n");
        while (!buf && avpriv_atomic_int_get(&pool->refcount) <= avpriv_atomic_int_get(&pool->nb_allocated))
            buf = get_pool(pool);
    }

342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358
    if (!buf)
        return pool_alloc_buffer(pool);

    /* keep the first entry, return the rest of the list to the pool */
    add_to_pool(buf->next);
    buf->next = NULL;

    ret = av_buffer_create(buf->data, pool->size, pool_release_buffer,
                           buf, 0);
    if (!ret) {
        add_to_pool(buf);
        return NULL;
    }
    avpriv_atomic_int_add_and_fetch(&pool->refcount, 1);

    return ret;
}