tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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buffer.c (10042B)

      1 /*
      2 * This file is part of FFmpeg.
      3 *
      4 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
     16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     17 */
     18 
     19 #include <stdatomic.h>
     20 #include <stdint.h>
     21 #include <string.h>
     22 
     23 #include "avassert.h"
     24 #include "buffer_internal.h"
     25 #include "common.h"
     26 #include "mem.h"
     27 #include "thread.h"
     28 
     29 static AVBufferRef *buffer_create(AVBuffer *buf, uint8_t *data, size_t size,
     30                                  void (*free)(void *opaque, uint8_t *data),
     31                                  void *opaque, int flags)
     32 {
     33    AVBufferRef *ref = NULL;
     34 
     35    buf->data     = data;
     36    buf->size     = size;
     37    buf->free     = free ? free : av_buffer_default_free;
     38    buf->opaque   = opaque;
     39 
     40    atomic_init(&buf->refcount, 1);
     41 
     42    buf->flags = flags;
     43 
     44    ref = av_mallocz(sizeof(*ref));
     45    if (!ref)
     46        return NULL;
     47 
     48    ref->buffer = buf;
     49    ref->data   = data;
     50    ref->size   = size;
     51 
     52    return ref;
     53 }
     54 
     55 AVBufferRef *av_buffer_create(uint8_t *data, size_t size,
     56                              void (*free)(void *opaque, uint8_t *data),
     57                              void *opaque, int flags)
     58 {
     59    AVBufferRef *ret;
     60    AVBuffer *buf = av_mallocz(sizeof(*buf));
     61    if (!buf)
     62        return NULL;
     63 
     64    ret = buffer_create(buf, data, size, free, opaque, flags);
     65    if (!ret) {
     66        av_free(buf);
     67        return NULL;
     68    }
     69    return ret;
     70 }
     71 
     72 void av_buffer_default_free(void *opaque, uint8_t *data)
     73 {
     74    av_free(data);
     75 }
     76 
     77 AVBufferRef *av_buffer_alloc(size_t size)
     78 {
     79    AVBufferRef *ret = NULL;
     80    uint8_t    *data = NULL;
     81 
     82    data = av_malloc(size);
     83    if (!data)
     84        return NULL;
     85 
     86    ret = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
     87    if (!ret)
     88        av_freep(&data);
     89 
     90    return ret;
     91 }
     92 
     93 AVBufferRef *av_buffer_allocz(size_t size)
     94 {
     95    AVBufferRef *ret = av_buffer_alloc(size);
     96    if (!ret)
     97        return NULL;
     98 
     99    memset(ret->data, 0, size);
    100    return ret;
    101 }
    102 
    103 AVBufferRef *av_buffer_ref(const AVBufferRef *buf)
    104 {
    105    AVBufferRef *ret = av_mallocz(sizeof(*ret));
    106 
    107    if (!ret)
    108        return NULL;
    109 
    110    *ret = *buf;
    111 
    112    atomic_fetch_add_explicit(&buf->buffer->refcount, 1, memory_order_relaxed);
    113 
    114    return ret;
    115 }
    116 
    117 static void buffer_replace(AVBufferRef **dst, AVBufferRef **src)
    118 {
    119    AVBuffer *b;
    120 
    121    b = (*dst)->buffer;
    122 
    123    if (src) {
    124        **dst = **src;
    125        av_freep(src);
    126    } else
    127        av_freep(dst);
    128 
    129    if (atomic_fetch_sub_explicit(&b->refcount, 1, memory_order_acq_rel) == 1) {
    130        /* b->free below might already free the structure containing *b,
    131         * so we have to read the flag now to avoid use-after-free. */
    132        int free_avbuffer = !(b->flags_internal & BUFFER_FLAG_NO_FREE);
    133        b->free(b->opaque, b->data);
    134        if (free_avbuffer)
    135            av_free(b);
    136    }
    137 }
    138 
    139 void av_buffer_unref(AVBufferRef **buf)
    140 {
    141    if (!buf || !*buf)
    142        return;
    143 
    144    buffer_replace(buf, NULL);
    145 }
    146 
    147 int av_buffer_is_writable(const AVBufferRef *buf)
    148 {
    149    if (buf->buffer->flags & AV_BUFFER_FLAG_READONLY)
    150        return 0;
    151 
    152    return atomic_load(&buf->buffer->refcount) == 1;
    153 }
    154 
    155 void *av_buffer_get_opaque(const AVBufferRef *buf)
    156 {
    157    return buf->buffer->opaque;
    158 }
    159 
    160 int av_buffer_get_ref_count(const AVBufferRef *buf)
    161 {
    162    return atomic_load(&buf->buffer->refcount);
    163 }
    164 
    165 int av_buffer_make_writable(AVBufferRef **pbuf)
    166 {
    167    AVBufferRef *newbuf, *buf = *pbuf;
    168 
    169    if (av_buffer_is_writable(buf))
    170        return 0;
    171 
    172    newbuf = av_buffer_alloc(buf->size);
    173    if (!newbuf)
    174        return AVERROR(ENOMEM);
    175 
    176    memcpy(newbuf->data, buf->data, buf->size);
    177 
    178    buffer_replace(pbuf, &newbuf);
    179 
    180    return 0;
    181 }
    182 
    183 int av_buffer_realloc(AVBufferRef **pbuf, size_t size)
    184 {
    185    AVBufferRef *buf = *pbuf;
    186    uint8_t *tmp;
    187    int ret;
    188 
    189    if (!buf) {
    190        /* allocate a new buffer with av_realloc(), so it will be reallocatable
    191         * later */
    192        uint8_t *data = av_realloc(NULL, size);
    193        if (!data)
    194            return AVERROR(ENOMEM);
    195 
    196        buf = av_buffer_create(data, size, av_buffer_default_free, NULL, 0);
    197        if (!buf) {
    198            av_freep(&data);
    199            return AVERROR(ENOMEM);
    200        }
    201 
    202        buf->buffer->flags_internal |= BUFFER_FLAG_REALLOCATABLE;
    203        *pbuf = buf;
    204 
    205        return 0;
    206    } else if (buf->size == size)
    207        return 0;
    208 
    209    if (!(buf->buffer->flags_internal & BUFFER_FLAG_REALLOCATABLE) ||
    210        !av_buffer_is_writable(buf) || buf->data != buf->buffer->data) {
    211        /* cannot realloc, allocate a new reallocable buffer and copy data */
    212        AVBufferRef *new = NULL;
    213 
    214        ret = av_buffer_realloc(&new, size);
    215        if (ret < 0)
    216            return ret;
    217 
    218        memcpy(new->data, buf->data, FFMIN(size, buf->size));
    219 
    220        buffer_replace(pbuf, &new);
    221        return 0;
    222    }
    223 
    224    tmp = av_realloc(buf->buffer->data, size);
    225    if (!tmp)
    226        return AVERROR(ENOMEM);
    227 
    228    buf->buffer->data = buf->data = tmp;
    229    buf->buffer->size = buf->size = size;
    230    return 0;
    231 }
    232 
    233 int av_buffer_replace(AVBufferRef **pdst, const AVBufferRef *src)
    234 {
    235    AVBufferRef *dst = *pdst;
    236    AVBufferRef *tmp;
    237 
    238    if (!src) {
    239        av_buffer_unref(pdst);
    240        return 0;
    241    }
    242 
    243    if (dst && dst->buffer == src->buffer) {
    244        /* make sure the data pointers match */
    245        dst->data = src->data;
    246        dst->size = src->size;
    247        return 0;
    248    }
    249 
    250    tmp = av_buffer_ref(src);
    251    if (!tmp)
    252        return AVERROR(ENOMEM);
    253 
    254    av_buffer_unref(pdst);
    255    *pdst = tmp;
    256    return 0;
    257 }
    258 
    259 AVBufferPool *av_buffer_pool_init2(size_t size, void *opaque,
    260                                   AVBufferRef* (*alloc)(void *opaque, size_t size),
    261                                   void (*pool_free)(void *opaque))
    262 {
    263    AVBufferPool *pool = av_mallocz(sizeof(*pool));
    264    if (!pool)
    265        return NULL;
    266 
    267    if (ff_mutex_init(&pool->mutex, NULL)) {
    268        av_free(pool);
    269        return NULL;
    270    }
    271 
    272    pool->size      = size;
    273    pool->opaque    = opaque;
    274    pool->alloc2    = alloc;
    275    pool->alloc     = av_buffer_alloc; // fallback
    276    pool->pool_free = pool_free;
    277 
    278    atomic_init(&pool->refcount, 1);
    279 
    280    return pool;
    281 }
    282 
    283 AVBufferPool *av_buffer_pool_init(size_t size, AVBufferRef* (*alloc)(size_t size))
    284 {
    285    AVBufferPool *pool = av_mallocz(sizeof(*pool));
    286    if (!pool)
    287        return NULL;
    288 
    289    if (ff_mutex_init(&pool->mutex, NULL)) {
    290        av_free(pool);
    291        return NULL;
    292    }
    293 
    294    pool->size     = size;
    295    pool->alloc    = alloc ? alloc : av_buffer_alloc;
    296 
    297    atomic_init(&pool->refcount, 1);
    298 
    299    return pool;
    300 }
    301 
    302 static void buffer_pool_flush(AVBufferPool *pool)
    303 {
    304    while (pool->pool) {
    305        BufferPoolEntry *buf = pool->pool;
    306        pool->pool = buf->next;
    307 
    308        buf->free(buf->opaque, buf->data);
    309        av_freep(&buf);
    310    }
    311 }
    312 
    313 /*
    314 * This function gets called when the pool has been uninited and
    315 * all the buffers returned to it.
    316 */
    317 static void buffer_pool_free(AVBufferPool *pool)
    318 {
    319    buffer_pool_flush(pool);
    320    ff_mutex_destroy(&pool->mutex);
    321 
    322    if (pool->pool_free)
    323        pool->pool_free(pool->opaque);
    324 
    325    av_freep(&pool);
    326 }
    327 
    328 void av_buffer_pool_uninit(AVBufferPool **ppool)
    329 {
    330    AVBufferPool *pool;
    331 
    332    if (!ppool || !*ppool)
    333        return;
    334    pool   = *ppool;
    335    *ppool = NULL;
    336 
    337    ff_mutex_lock(&pool->mutex);
    338    buffer_pool_flush(pool);
    339    ff_mutex_unlock(&pool->mutex);
    340 
    341    if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
    342        buffer_pool_free(pool);
    343 }
    344 
    345 static void pool_release_buffer(void *opaque, uint8_t *data)
    346 {
    347    BufferPoolEntry *buf = opaque;
    348    AVBufferPool *pool = buf->pool;
    349 
    350    ff_mutex_lock(&pool->mutex);
    351    buf->next = pool->pool;
    352    pool->pool = buf;
    353    ff_mutex_unlock(&pool->mutex);
    354 
    355    if (atomic_fetch_sub_explicit(&pool->refcount, 1, memory_order_acq_rel) == 1)
    356        buffer_pool_free(pool);
    357 }
    358 
    359 /* allocate a new buffer and override its free() callback so that
    360 * it is returned to the pool on free */
    361 static AVBufferRef *pool_alloc_buffer(AVBufferPool *pool)
    362 {
    363    BufferPoolEntry *buf;
    364    AVBufferRef     *ret;
    365 
    366    av_assert0(pool->alloc || pool->alloc2);
    367 
    368    ret = pool->alloc2 ? pool->alloc2(pool->opaque, pool->size) :
    369                         pool->alloc(pool->size);
    370    if (!ret)
    371        return NULL;
    372 
    373    buf = av_mallocz(sizeof(*buf));
    374    if (!buf) {
    375        av_buffer_unref(&ret);
    376        return NULL;
    377    }
    378 
    379    buf->data   = ret->buffer->data;
    380    buf->opaque = ret->buffer->opaque;
    381    buf->free   = ret->buffer->free;
    382    buf->pool   = pool;
    383 
    384    ret->buffer->opaque = buf;
    385    ret->buffer->free   = pool_release_buffer;
    386 
    387    return ret;
    388 }
    389 
    390 AVBufferRef *av_buffer_pool_get(AVBufferPool *pool)
    391 {
    392    AVBufferRef *ret;
    393    BufferPoolEntry *buf;
    394 
    395    ff_mutex_lock(&pool->mutex);
    396    buf = pool->pool;
    397    if (buf) {
    398        memset(&buf->buffer, 0, sizeof(buf->buffer));
    399        ret = buffer_create(&buf->buffer, buf->data, pool->size,
    400                            pool_release_buffer, buf, 0);
    401        if (ret) {
    402            pool->pool = buf->next;
    403            buf->next = NULL;
    404            buf->buffer.flags_internal |= BUFFER_FLAG_NO_FREE;
    405        }
    406    } else {
    407        ret = pool_alloc_buffer(pool);
    408    }
    409    ff_mutex_unlock(&pool->mutex);
    410 
    411    if (ret)
    412        atomic_fetch_add_explicit(&pool->refcount, 1, memory_order_relaxed);
    413 
    414    return ret;
    415 }
    416 
    417 void *av_buffer_pool_buffer_get_opaque(const AVBufferRef *ref)
    418 {
    419    BufferPoolEntry *buf = ref->buffer->opaque;
    420    av_assert0(buf);
    421    return buf->opaque;
    422 }