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FFmpeg/libavformat/aviobuf.c
Luca Barbato 3c18a7b188 avio: Do not consider the end-of-buffer position valid 
Trigger a refill if the seek action moves the pointer
at the end of the buffer.

Before this patch the read action following the seek would trigger
the refill, while write action would write outside the buffer.

In the Libav codebase few muxers seek forward outside of what
already has been written so it is quite unlikely to experience
the problem with the default buffer size.

CC: libav-stable@libav.org
2015-01-28 16:28:10 +01:00

1026 lines
25 KiB
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/*
* buffered I/O
* Copyright (c) 2000,2001 Fabrice Bellard
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* 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.
*
* Libav is distributed in the hope that it will be useful,
* 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
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/crc.h"
#include "libavutil/dict.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/log.h"
#include "libavutil/opt.h"
#include "avformat.h"
#include "avio.h"
#include "avio_internal.h"
#include "internal.h"
#include "url.h"
#include <stdarg.h>
#define IO_BUFFER_SIZE 32768
/**
* Do seeks within this distance ahead of the current buffer by skipping
* data instead of calling the protocol seek function, for seekable
* protocols.
*/
#define SHORT_SEEK_THRESHOLD 4096
static void *ffio_url_child_next(void *obj, void *prev)
{
AVIOContext *s = obj;
return prev ? NULL : s->opaque;
}
static const AVClass *ffio_url_child_class_next(const AVClass *prev)
{
return prev ? NULL : &ffurl_context_class;
}
static const AVOption ffio_url_options[] = {
{ NULL },
};
const AVClass ffio_url_class = {
.class_name = "AVIOContext",
.item_name = av_default_item_name,
.version = LIBAVUTIL_VERSION_INT,
.option = ffio_url_options,
.child_next = ffio_url_child_next,
.child_class_next = ffio_url_child_class_next,
};
static void fill_buffer(AVIOContext *s);
static int url_resetbuf(AVIOContext *s, int flags);
int ffio_init_context(AVIOContext *s,
unsigned char *buffer,
int buffer_size,
int write_flag,
void *opaque,
int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
int64_t (*seek)(void *opaque, int64_t offset, int whence))
{
s->buffer = buffer;
s->buffer_size = buffer_size;
s->buf_ptr = buffer;
s->opaque = opaque;
url_resetbuf(s, write_flag ? AVIO_FLAG_WRITE : AVIO_FLAG_READ);
s->write_packet = write_packet;
s->read_packet = read_packet;
s->seek = seek;
s->pos = 0;
s->must_flush = 0;
s->eof_reached = 0;
s->error = 0;
s->seekable = seek ? AVIO_SEEKABLE_NORMAL : 0;
s->max_packet_size = 0;
s->update_checksum = NULL;
if (!read_packet && !write_flag) {
s->pos = buffer_size;
s->buf_end = s->buffer + buffer_size;
}
s->read_pause = NULL;
s->read_seek = NULL;
return 0;
}
AVIOContext *avio_alloc_context(
unsigned char *buffer,
int buffer_size,
int write_flag,
void *opaque,
int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
int64_t (*seek)(void *opaque, int64_t offset, int whence))
{
AVIOContext *s = av_mallocz(sizeof(AVIOContext));
if (!s)
return NULL;
ffio_init_context(s, buffer, buffer_size, write_flag, opaque,
read_packet, write_packet, seek);
return s;
}
static void flush_buffer(AVIOContext *s)
{
if (s->buf_ptr > s->buffer) {
if (s->write_packet && !s->error) {
int ret = s->write_packet(s->opaque, s->buffer,
s->buf_ptr - s->buffer);
if (ret < 0) {
s->error = ret;
}
}
if (s->update_checksum) {
s->checksum = s->update_checksum(s->checksum, s->checksum_ptr,
s->buf_ptr - s->checksum_ptr);
s->checksum_ptr = s->buffer;
}
s->pos += s->buf_ptr - s->buffer;
}
s->buf_ptr = s->buffer;
}
void avio_w8(AVIOContext *s, int b)
{
*s->buf_ptr++ = b;
if (s->buf_ptr >= s->buf_end)
flush_buffer(s);
}
void ffio_fill(AVIOContext *s, int b, int count)
{
while (count > 0) {
int len = FFMIN(s->buf_end - s->buf_ptr, count);
memset(s->buf_ptr, b, len);
s->buf_ptr += len;
if (s->buf_ptr >= s->buf_end)
flush_buffer(s);
count -= len;
}
}
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
{
while (size > 0) {
int len = FFMIN(s->buf_end - s->buf_ptr, size);
memcpy(s->buf_ptr, buf, len);
s->buf_ptr += len;
if (s->buf_ptr >= s->buf_end)
flush_buffer(s);
buf += len;
size -= len;
}
}
void avio_flush(AVIOContext *s)
{
flush_buffer(s);
s->must_flush = 0;
}
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
{
int64_t offset1;
int64_t pos;
int force = whence & AVSEEK_FORCE;
whence &= ~AVSEEK_FORCE;
if(!s)
return AVERROR(EINVAL);
pos = s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
if (whence != SEEK_CUR && whence != SEEK_SET)
return AVERROR(EINVAL);
if (whence == SEEK_CUR) {
offset1 = pos + (s->buf_ptr - s->buffer);
if (offset == 0)
return offset1;
offset += offset1;
}
offset1 = offset - pos;
if (!s->must_flush &&
offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
/* can do the seek inside the buffer */
s->buf_ptr = s->buffer + offset1;
} else if ((!s->seekable ||
offset1 <= s->buf_end + SHORT_SEEK_THRESHOLD - s->buffer) &&
!s->write_flag && offset1 >= 0 &&
(whence != SEEK_END || force)) {
while(s->pos < offset && !s->eof_reached)
fill_buffer(s);
if (s->eof_reached)
return AVERROR_EOF;
s->buf_ptr = s->buf_end + offset - s->pos;
} else {
int64_t res;
if (s->write_flag) {
flush_buffer(s);
s->must_flush = 1;
}
if (!s->seek)
return AVERROR(EPIPE);
if ((res = s->seek(s->opaque, offset, SEEK_SET)) < 0)
return res;
if (!s->write_flag)
s->buf_end = s->buffer;
s->buf_ptr = s->buffer;
s->pos = offset;
}
s->eof_reached = 0;
return offset;
}
int64_t avio_size(AVIOContext *s)
{
int64_t size;
if (!s)
return AVERROR(EINVAL);
if (!s->seek)
return AVERROR(ENOSYS);
size = s->seek(s->opaque, 0, AVSEEK_SIZE);
if (size < 0) {
if ((size = s->seek(s->opaque, -1, SEEK_END)) < 0)
return size;
size++;
s->seek(s->opaque, s->pos, SEEK_SET);
}
return size;
}
void avio_wl32(AVIOContext *s, unsigned int val)
{
avio_w8(s, val);
avio_w8(s, val >> 8);
avio_w8(s, val >> 16);
avio_w8(s, val >> 24);
}
void avio_wb32(AVIOContext *s, unsigned int val)
{
avio_w8(s, val >> 24);
avio_w8(s, val >> 16);
avio_w8(s, val >> 8);
avio_w8(s, val);
}
int avio_put_str(AVIOContext *s, const char *str)
{
int len = 1;
if (str) {
len += strlen(str);
avio_write(s, (const unsigned char *) str, len);
} else
avio_w8(s, 0);
return len;
}
int avio_put_str16le(AVIOContext *s, const char *str)
{
const uint8_t *q = str;
int ret = 0;
while (*q) {
uint32_t ch;
uint16_t tmp;
GET_UTF8(ch, *q++, break;)
PUT_UTF16(ch, tmp, avio_wl16(s, tmp); ret += 2;)
}
avio_wl16(s, 0);
ret += 2;
return ret;
}
int ff_get_v_length(uint64_t val)
{
int i = 1;
while (val >>= 7)
i++;
return i;
}
void ff_put_v(AVIOContext *bc, uint64_t val)
{
int i = ff_get_v_length(val);
while (--i > 0)
avio_w8(bc, 128 | (val >> (7 * i)));
avio_w8(bc, val & 127);
}
void avio_wl64(AVIOContext *s, uint64_t val)
{
avio_wl32(s, (uint32_t)(val & 0xffffffff));
avio_wl32(s, (uint32_t)(val >> 32));
}
void avio_wb64(AVIOContext *s, uint64_t val)
{
avio_wb32(s, (uint32_t)(val >> 32));
avio_wb32(s, (uint32_t)(val & 0xffffffff));
}
void avio_wl16(AVIOContext *s, unsigned int val)
{
avio_w8(s, val);
avio_w8(s, val >> 8);
}
void avio_wb16(AVIOContext *s, unsigned int val)
{
avio_w8(s, val >> 8);
avio_w8(s, val);
}
void avio_wl24(AVIOContext *s, unsigned int val)
{
avio_wl16(s, val & 0xffff);
avio_w8(s, val >> 16);
}
void avio_wb24(AVIOContext *s, unsigned int val)
{
avio_wb16(s, val >> 8);
avio_w8(s, val);
}
/* Input stream */
static void fill_buffer(AVIOContext *s)
{
uint8_t *dst = !s->max_packet_size &&
s->buf_end - s->buffer < s->buffer_size ?
s->buf_end : s->buffer;
int len = s->buffer_size - (dst - s->buffer);
int max_buffer_size = s->max_packet_size ?
s->max_packet_size : IO_BUFFER_SIZE;
/* can't fill the buffer without read_packet, just set EOF if appropriate */
if (!s->read_packet && s->buf_ptr >= s->buf_end)
s->eof_reached = 1;
/* no need to do anything if EOF already reached */
if (s->eof_reached)
return;
if (s->update_checksum && dst == s->buffer) {
if (s->buf_end > s->checksum_ptr)
s->checksum = s->update_checksum(s->checksum, s->checksum_ptr,
s->buf_end - s->checksum_ptr);
s->checksum_ptr = s->buffer;
}
/* make buffer smaller in case it ended up large after probing */
if (s->buffer_size > max_buffer_size) {
ffio_set_buf_size(s, max_buffer_size);
s->checksum_ptr = dst = s->buffer;
len = s->buffer_size;
}
if (s->read_packet)
len = s->read_packet(s->opaque, dst, len);
else
len = 0;
if (len <= 0) {
/* do not modify buffer if EOF reached so that a seek back can
be done without rereading data */
s->eof_reached = 1;
if (len < 0)
s->error = len;
} else {
s->pos += len;
s->buf_ptr = dst;
s->buf_end = dst + len;
}
}
unsigned long ff_crc04C11DB7_update(unsigned long checksum, const uint8_t *buf,
unsigned int len)
{
return av_crc(av_crc_get_table(AV_CRC_32_IEEE), checksum, buf, len);
}
unsigned long ff_crcA001_update(unsigned long checksum, const uint8_t *buf,
unsigned int len)
{
return av_crc(av_crc_get_table(AV_CRC_16_ANSI_LE), checksum, buf, len);
}
unsigned long ffio_get_checksum(AVIOContext *s)
{
s->checksum = s->update_checksum(s->checksum, s->checksum_ptr,
s->buf_ptr - s->checksum_ptr);
s->update_checksum = NULL;
return s->checksum;
}
void ffio_init_checksum(AVIOContext *s,
unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len),
unsigned long checksum)
{
s->update_checksum = update_checksum;
if (s->update_checksum) {
s->checksum = checksum;
s->checksum_ptr = s->buf_ptr;
}
}
/* XXX: put an inline version */
int avio_r8(AVIOContext *s)
{
if (s->buf_ptr >= s->buf_end)
fill_buffer(s);
if (s->buf_ptr < s->buf_end)
return *s->buf_ptr++;
return 0;
}
int avio_read(AVIOContext *s, unsigned char *buf, int size)
{
int len, size1;
size1 = size;
while (size > 0) {
len = s->buf_end - s->buf_ptr;
if (len > size)
len = size;
if (len == 0 || s->write_flag) {
if(size > s->buffer_size && !s->update_checksum){
if(s->read_packet)
len = s->read_packet(s->opaque, buf, size);
if (len <= 0) {
/* do not modify buffer if EOF reached so that a seek back can
be done without rereading data */
s->eof_reached = 1;
if(len<0)
s->error= len;
break;
} else {
s->pos += len;
size -= len;
buf += len;
s->buf_ptr = s->buffer;
s->buf_end = s->buffer/* + len*/;
}
} else {
fill_buffer(s);
len = s->buf_end - s->buf_ptr;
if (len == 0)
break;
}
} else {
memcpy(buf, s->buf_ptr, len);
buf += len;
s->buf_ptr += len;
size -= len;
}
}
if (size1 == size) {
if (s->error) return s->error;
if (s->eof_reached) return AVERROR_EOF;
}
return size1 - size;
}
int ffio_read_indirect(AVIOContext *s, unsigned char *buf, int size, const unsigned char **data)
{
if (s->buf_end - s->buf_ptr >= size && !s->write_flag) {
*data = s->buf_ptr;
s->buf_ptr += size;
return size;
} else {
*data = buf;
return avio_read(s, buf, size);
}
}
int ffio_read_partial(AVIOContext *s, unsigned char *buf, int size)
{
int len;
if (size < 0)
return -1;
if (s->read_packet && s->write_flag) {
len = s->read_packet(s->opaque, buf, size);
if (len > 0)
s->pos += len;
return len;
}
len = s->buf_end - s->buf_ptr;
if (len == 0) {
/* Reset the buf_end pointer to the start of the buffer, to make sure
* the fill_buffer call tries to read as much data as fits into the
* full buffer, instead of just what space is left after buf_end.
* This avoids returning partial packets at the end of the buffer,
* for packet based inputs.
*/
s->buf_end = s->buf_ptr = s->buffer;
fill_buffer(s);
len = s->buf_end - s->buf_ptr;
}
if (len > size)
len = size;
memcpy(buf, s->buf_ptr, len);
s->buf_ptr += len;
if (!len) {
if (s->error) return s->error;
if (s->eof_reached) return AVERROR_EOF;
}
return len;
}
unsigned int avio_rl16(AVIOContext *s)
{
unsigned int val;
val = avio_r8(s);
val |= avio_r8(s) << 8;
return val;
}
unsigned int avio_rl24(AVIOContext *s)
{
unsigned int val;
val = avio_rl16(s);
val |= avio_r8(s) << 16;
return val;
}
unsigned int avio_rl32(AVIOContext *s)
{
unsigned int val;
val = avio_rl16(s);
val |= avio_rl16(s) << 16;
return val;
}
uint64_t avio_rl64(AVIOContext *s)
{
uint64_t val;
val = (uint64_t)avio_rl32(s);
val |= (uint64_t)avio_rl32(s) << 32;
return val;
}
unsigned int avio_rb16(AVIOContext *s)
{
unsigned int val;
val = avio_r8(s) << 8;
val |= avio_r8(s);
return val;
}
unsigned int avio_rb24(AVIOContext *s)
{
unsigned int val;
val = avio_rb16(s) << 8;
val |= avio_r8(s);
return val;
}
unsigned int avio_rb32(AVIOContext *s)
{
unsigned int val;
val = avio_rb16(s) << 16;
val |= avio_rb16(s);
return val;
}
int ff_get_line(AVIOContext *s, char *buf, int maxlen)
{
int i = 0;
char c;
do {
c = avio_r8(s);
if (c && i < maxlen-1)
buf[i++] = c;
} while (c != '\n' && c);
buf[i] = 0;
return i;
}
int avio_get_str(AVIOContext *s, int maxlen, char *buf, int buflen)
{
int i;
if (buflen <= 0)
return AVERROR(EINVAL);
// reserve 1 byte for terminating 0
buflen = FFMIN(buflen - 1, maxlen);
for (i = 0; i < buflen; i++)
if (!(buf[i] = avio_r8(s)))
return i + 1;
buf[i] = 0;
for (; i < maxlen; i++)
if (!avio_r8(s))
return i + 1;
return maxlen;
}
#define GET_STR16(type, read) \
int avio_get_str16 ##type(AVIOContext *pb, int maxlen, char *buf, int buflen)\
{\
char* q = buf;\
int ret = 0;\
if (buflen <= 0) \
return AVERROR(EINVAL); \
while (ret + 1 < maxlen) {\
uint8_t tmp;\
uint32_t ch;\
GET_UTF16(ch, (ret += 2) <= maxlen ? read(pb) : 0, break;)\
if (!ch)\
break;\
PUT_UTF8(ch, tmp, if (q - buf < buflen - 1) *q++ = tmp;)\
}\
*q = 0;\
return ret;\
}\
GET_STR16(le, avio_rl16)
GET_STR16(be, avio_rb16)
#undef GET_STR16
uint64_t avio_rb64(AVIOContext *s)
{
uint64_t val;
val = (uint64_t)avio_rb32(s) << 32;
val |= (uint64_t)avio_rb32(s);
return val;
}
uint64_t ffio_read_varlen(AVIOContext *bc){
uint64_t val = 0;
int tmp;
do{
tmp = avio_r8(bc);
val= (val<<7) + (tmp&127);
}while(tmp&128);
return val;
}
int ffio_fdopen(AVIOContext **s, URLContext *h)
{
uint8_t *buffer;
int buffer_size, max_packet_size;
max_packet_size = h->max_packet_size;
if (max_packet_size) {
buffer_size = max_packet_size; /* no need to bufferize more than one packet */
} else {
buffer_size = IO_BUFFER_SIZE;
}
buffer = av_malloc(buffer_size);
if (!buffer)
return AVERROR(ENOMEM);
*s = avio_alloc_context(buffer, buffer_size, h->flags & AVIO_FLAG_WRITE, h,
ffurl_read, ffurl_write, ffurl_seek);
if (!*s) {
av_free(buffer);
return AVERROR(ENOMEM);
}
(*s)->seekable = h->is_streamed ? 0 : AVIO_SEEKABLE_NORMAL;
(*s)->max_packet_size = max_packet_size;
if(h->prot) {
(*s)->read_pause = (int (*)(void *, int))h->prot->url_read_pause;
(*s)->read_seek = (int64_t (*)(void *, int, int64_t, int))h->prot->url_read_seek;
}
(*s)->av_class = &ffio_url_class;
return 0;
}
int ffio_set_buf_size(AVIOContext *s, int buf_size)
{
uint8_t *buffer;
buffer = av_malloc(buf_size);
if (!buffer)
return AVERROR(ENOMEM);
av_free(s->buffer);
s->buffer = buffer;
s->buffer_size = buf_size;
s->buf_ptr = buffer;
url_resetbuf(s, s->write_flag ? AVIO_FLAG_WRITE : AVIO_FLAG_READ);
return 0;
}
static int url_resetbuf(AVIOContext *s, int flags)
{
assert(flags == AVIO_FLAG_WRITE || flags == AVIO_FLAG_READ);
if (flags & AVIO_FLAG_WRITE) {
s->buf_end = s->buffer + s->buffer_size;
s->write_flag = 1;
} else {
s->buf_end = s->buffer;
s->write_flag = 0;
}
return 0;
}
int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char *buf, int buf_size)
{
int64_t buffer_start;
int buffer_size;
int overlap, new_size, alloc_size;
if (s->write_flag)
return AVERROR(EINVAL);
buffer_size = s->buf_end - s->buffer;
/* the buffers must touch or overlap */
if ((buffer_start = s->pos - buffer_size) > buf_size)
return AVERROR(EINVAL);
overlap = buf_size - buffer_start;
new_size = buf_size + buffer_size - overlap;
alloc_size = FFMAX(s->buffer_size, new_size);
if (alloc_size > buf_size)
if (!(buf = av_realloc(buf, alloc_size)))
return AVERROR(ENOMEM);
if (new_size > buf_size) {
memcpy(buf + buf_size, s->buffer + overlap, buffer_size - overlap);
buf_size = new_size;
}
av_free(s->buffer);
s->buf_ptr = s->buffer = buf;
s->buffer_size = alloc_size;
s->pos = buf_size;
s->buf_end = s->buf_ptr + buf_size;
s->eof_reached = 0;
s->must_flush = 0;
return 0;
}
int avio_open(AVIOContext **s, const char *filename, int flags)
{
return avio_open2(s, filename, flags, NULL, NULL);
}
int avio_open2(AVIOContext **s, const char *filename, int flags,
const AVIOInterruptCB *int_cb, AVDictionary **options)
{
URLContext *h;
int err;
err = ffurl_open(&h, filename, flags, int_cb, options);
if (err < 0)
return err;
err = ffio_fdopen(s, h);
if (err < 0) {
ffurl_close(h);
return err;
}
return 0;
}
int avio_close(AVIOContext *s)
{
URLContext *h;
if (!s)
return 0;
avio_flush(s);
h = s->opaque;
av_freep(&s->buffer);
av_free(s);
return ffurl_close(h);
}
int avio_closep(AVIOContext **s)
{
int ret = avio_close(*s);
*s = NULL;
return ret;
}
int avio_printf(AVIOContext *s, const char *fmt, ...)
{
va_list ap;
char buf[4096];
int ret;
va_start(ap, fmt);
ret = vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
avio_write(s, buf, strlen(buf));
return ret;
}
int avio_pause(AVIOContext *s, int pause)
{
if (!s->read_pause)
return AVERROR(ENOSYS);
return s->read_pause(s->opaque, pause);
}
int64_t avio_seek_time(AVIOContext *s, int stream_index,
int64_t timestamp, int flags)
{
URLContext *h = s->opaque;
int64_t ret;
if (!s->read_seek)
return AVERROR(ENOSYS);
ret = s->read_seek(h, stream_index, timestamp, flags);
if (ret >= 0) {
int64_t pos;
s->buf_ptr = s->buf_end; // Flush buffer
pos = s->seek(h, 0, SEEK_CUR);
if (pos >= 0)
s->pos = pos;
else if (pos != AVERROR(ENOSYS))
ret = pos;
}
return ret;
}
/* output in a dynamic buffer */
typedef struct DynBuffer {
int pos, size, allocated_size;
uint8_t *buffer;
int io_buffer_size;
uint8_t io_buffer[1];
} DynBuffer;
static int dyn_buf_write(void *opaque, uint8_t *buf, int buf_size)
{
DynBuffer *d = opaque;
unsigned new_size, new_allocated_size;
/* reallocate buffer if needed */
new_size = d->pos + buf_size;
new_allocated_size = d->allocated_size;
if (new_size < d->pos || new_size > INT_MAX/2)
return -1;
while (new_size > new_allocated_size) {
if (!new_allocated_size)
new_allocated_size = new_size;
else
new_allocated_size += new_allocated_size / 2 + 1;
}
if (new_allocated_size > d->allocated_size) {
int err;
if ((err = av_reallocp(&d->buffer, new_allocated_size)) < 0) {
d->allocated_size = 0;
d->size = 0;
return err;
}
d->allocated_size = new_allocated_size;
}
memcpy(d->buffer + d->pos, buf, buf_size);
d->pos = new_size;
if (d->pos > d->size)
d->size = d->pos;
return buf_size;
}
static int dyn_packet_buf_write(void *opaque, uint8_t *buf, int buf_size)
{
unsigned char buf1[4];
int ret;
/* packetized write: output the header */
AV_WB32(buf1, buf_size);
ret = dyn_buf_write(opaque, buf1, 4);
if (ret < 0)
return ret;
/* then the data */
return dyn_buf_write(opaque, buf, buf_size);
}
static int64_t dyn_buf_seek(void *opaque, int64_t offset, int whence)
{
DynBuffer *d = opaque;
if (whence == SEEK_CUR)
offset += d->pos;
else if (whence == SEEK_END)
offset += d->size;
if (offset < 0 || offset > 0x7fffffffLL)
return -1;
d->pos = offset;
return 0;
}
static int url_open_dyn_buf_internal(AVIOContext **s, int max_packet_size)
{
DynBuffer *d;
unsigned io_buffer_size = max_packet_size ? max_packet_size : 1024;
if (sizeof(DynBuffer) + io_buffer_size < io_buffer_size)
return -1;
d = av_mallocz(sizeof(DynBuffer) + io_buffer_size);
if (!d)
return AVERROR(ENOMEM);
d->io_buffer_size = io_buffer_size;
*s = avio_alloc_context(d->io_buffer, d->io_buffer_size, 1, d, NULL,
max_packet_size ? dyn_packet_buf_write : dyn_buf_write,
max_packet_size ? NULL : dyn_buf_seek);
if(!*s) {
av_free(d);
return AVERROR(ENOMEM);
}
(*s)->max_packet_size = max_packet_size;
return 0;
}
int avio_open_dyn_buf(AVIOContext **s)
{
return url_open_dyn_buf_internal(s, 0);
}
int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size)
{
if (max_packet_size <= 0)
return -1;
return url_open_dyn_buf_internal(s, max_packet_size);
}
int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer)
{
DynBuffer *d;
int size;
static const char padbuf[FF_INPUT_BUFFER_PADDING_SIZE] = {0};
int padding = 0;
if (!s) {
*pbuffer = NULL;
return 0;
}
/* don't attempt to pad fixed-size packet buffers */
if (!s->max_packet_size) {
avio_write(s, padbuf, sizeof(padbuf));
padding = FF_INPUT_BUFFER_PADDING_SIZE;
}
avio_flush(s);
d = s->opaque;
*pbuffer = d->buffer;
size = d->size;
av_free(d);
av_free(s);
return size - padding;
}
static int null_buf_write(void *opaque, uint8_t *buf, int buf_size)
{
DynBuffer *d = opaque;
d->pos += buf_size;
if (d->pos > d->size)
d->size = d->pos;
return buf_size;
}
int ffio_open_null_buf(AVIOContext **s)
{
int ret = url_open_dyn_buf_internal(s, 0);
if (ret >= 0) {
AVIOContext *pb = *s;
pb->write_packet = null_buf_write;
}
return ret;
}
int ffio_close_null_buf(AVIOContext *s)
{
DynBuffer *d = s->opaque;
int size;
avio_flush(s);
size = d->size;
av_free(d);
av_free(s);
return size;
}
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