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FFmpeg/libavcodec/cbs_jpeg.c
Andreas Rheinhardt 4e7e30bbe0 cbs: Don't set AVBuffer's opaque 
cbs is currently inconsistent regarding the opaque field that can be
used as a special argument to av_buffer_create in order to be used
during freeing the buffer: ff_cbs_alloc_unit_content and all the free
functions used name this parameter as if it should contain a pointer to
the unit whose content is about to be created; but both
ff_cbs_alloc_unit_content as well as ff_cbs_h264_add_sei_message
actually use a pointer to the CodedBitstreamContext as opaque. It should
actually be neither, because it is unneeded (as is evidenced by the fact
that none of the free functions use this pointer at all) and because it
ties the unit's content to the lifetime of other objects, although a
refcounted buffer is supposed to have its own lifetime that only ends
when its reference count reaches zero. This problem manifests itself in
the pointer becoming dangling.
The pointer to the unit can become dangling if another unit is added to
the fragment later as happens in the bitstream filters; in this case,
the pointer can point to the wrong unit (if the fragment's unit array
needn't be relocated) or it can point to where the array was earlier.
It can also become dangling if the unit's content is meant to survive
the resetting of the fragment it was originally read with. This applies
to the extradata of H.264 and HEVC.
The pointer to the context can become dangling if the context is closed
before the content is freed. Although this doesn't seem to happen right
now, it could happen, in particular if one uses different
CodedBitstreamContexts for in- and output.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2019-07-29 22:25:10 +01:00

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/*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "cbs.h"
#include "cbs_internal.h"
#include "cbs_jpeg.h"
#define HEADER(name) do { \
ff_cbs_trace_header(ctx, name); \
} while (0)
#define CHECK(call) do { \
err = (call); \
if (err < 0) \
return err; \
} while (0)
#define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
#define u(width, name, range_min, range_max) \
xu(width, name, range_min, range_max, 0)
#define us(width, name, sub, range_min, range_max) \
xu(width, name, range_min, range_max, 1, sub)
#define READ
#define READWRITE read
#define RWContext GetBitContext
#define FUNC(name) cbs_jpeg_read_ ## name
#define xu(width, name, range_min, range_max, subs, ...) do { \
uint32_t value; \
CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), \
&value, range_min, range_max)); \
current->name = value; \
} while (0)
#include "cbs_jpeg_syntax_template.c"
#undef READ
#undef READWRITE
#undef RWContext
#undef FUNC
#undef xu
#define WRITE
#define READWRITE write
#define RWContext PutBitContext
#define FUNC(name) cbs_jpeg_write_ ## name
#define xu(width, name, range_min, range_max, subs, ...) do { \
uint32_t value = current->name; \
CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), \
value, range_min, range_max)); \
} while (0)
#include "cbs_jpeg_syntax_template.c"
#undef WRITE
#undef READWRITE
#undef RWContext
#undef FUNC
#undef xu
static void cbs_jpeg_free_application_data(void *opaque, uint8_t *content)
{
JPEGRawApplicationData *ad = (JPEGRawApplicationData*)content;
av_buffer_unref(&ad->Ap_ref);
av_freep(&content);
}
static void cbs_jpeg_free_comment(void *opaque, uint8_t *content)
{
JPEGRawComment *comment = (JPEGRawComment*)content;
av_buffer_unref(&comment->Cm_ref);
av_freep(&content);
}
static void cbs_jpeg_free_scan(void *opaque, uint8_t *content)
{
JPEGRawScan *scan = (JPEGRawScan*)content;
av_buffer_unref(&scan->data_ref);
av_freep(&content);
}
static int cbs_jpeg_split_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int header)
{
AVBufferRef *data_ref;
uint8_t *data;
size_t data_size;
int unit, start, end, marker, next_start, next_marker;
int err, i, j, length;
if (frag->data_size < 4) {
// Definitely too short to be meaningful.
return AVERROR_INVALIDDATA;
}
for (i = 0; i + 1 < frag->data_size && frag->data[i] != 0xff; i++);
if (i > 0) {
av_log(ctx->log_ctx, AV_LOG_WARNING, "Discarding %d bytes at "
"beginning of image.\n", i);
}
for (++i; i + 1 < frag->data_size && frag->data[i] == 0xff; i++);
if (i + 1 >= frag->data_size && frag->data[i]) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid JPEG image: "
"no SOI marker found.\n");
return AVERROR_INVALIDDATA;
}
marker = frag->data[i];
if (marker != JPEG_MARKER_SOI) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid JPEG image: first "
"marker is %02x, should be SOI.\n", marker);
return AVERROR_INVALIDDATA;
}
for (++i; i + 1 < frag->data_size && frag->data[i] == 0xff; i++);
if (i + 1 >= frag->data_size) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid JPEG image: "
"no image content found.\n");
return AVERROR_INVALIDDATA;
}
marker = frag->data[i];
start = i + 1;
for (unit = 0;; unit++) {
if (marker == JPEG_MARKER_EOI) {
break;
} else if (marker == JPEG_MARKER_SOS) {
for (i = start; i + 1 < frag->data_size; i++) {
if (frag->data[i] != 0xff)
continue;
end = i;
for (++i; i + 1 < frag->data_size &&
frag->data[i] == 0xff; i++);
if (i + 1 >= frag->data_size) {
next_marker = -1;
} else {
if (frag->data[i] == 0x00)
continue;
next_marker = frag->data[i];
next_start = i + 1;
}
break;
}
} else {
i = start;
if (i + 2 > frag->data_size) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid JPEG image: "
"truncated at %02x marker.\n", marker);
return AVERROR_INVALIDDATA;
}
length = AV_RB16(frag->data + i);
if (i + length > frag->data_size) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid JPEG image: "
"truncated at %02x marker segment.\n", marker);
return AVERROR_INVALIDDATA;
}
end = start + length;
i = end;
if (frag->data[i] != 0xff) {
next_marker = -1;
} else {
for (++i; i + 1 < frag->data_size &&
frag->data[i] == 0xff; i++);
if (i + 1 >= frag->data_size) {
next_marker = -1;
} else {
next_marker = frag->data[i];
next_start = i + 1;
}
}
}
if (marker == JPEG_MARKER_SOS) {
length = AV_RB16(frag->data + start);
data_ref = NULL;
data = av_malloc(end - start +
AV_INPUT_BUFFER_PADDING_SIZE);
if (!data)
return AVERROR(ENOMEM);
memcpy(data, frag->data + start, length);
for (i = start + length, j = length; i < end; i++, j++) {
if (frag->data[i] == 0xff) {
while (frag->data[i] == 0xff)
++i;
data[j] = 0xff;
} else {
data[j] = frag->data[i];
}
}
data_size = j;
memset(data + data_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
} else {
data = frag->data + start;
data_size = end - start;
data_ref = frag->data_ref;
}
err = ff_cbs_insert_unit_data(ctx, frag, unit, marker,
data, data_size, data_ref);
if (err < 0) {
if (!data_ref)
av_freep(&data);
return err;
}
if (next_marker == -1)
break;
marker = next_marker;
start = next_start;
}
return 0;
}
static int cbs_jpeg_read_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
GetBitContext gbc;
int err;
err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
if (err < 0)
return err;
if (unit->type >= JPEG_MARKER_SOF0 &&
unit->type <= JPEG_MARKER_SOF3) {
err = ff_cbs_alloc_unit_content(ctx, unit,
sizeof(JPEGRawFrameHeader),
NULL);
if (err < 0)
return err;
err = cbs_jpeg_read_frame_header(ctx, &gbc, unit->content);
if (err < 0)
return err;
} else if (unit->type >= JPEG_MARKER_APPN &&
unit->type <= JPEG_MARKER_APPN + 15) {
err = ff_cbs_alloc_unit_content(ctx, unit,
sizeof(JPEGRawApplicationData),
&cbs_jpeg_free_application_data);
if (err < 0)
return err;
err = cbs_jpeg_read_application_data(ctx, &gbc, unit->content);
if (err < 0)
return err;
} else if (unit->type == JPEG_MARKER_SOS) {
JPEGRawScan *scan;
int pos;
err = ff_cbs_alloc_unit_content(ctx, unit,
sizeof(JPEGRawScan),
&cbs_jpeg_free_scan);
if (err < 0)
return err;
scan = unit->content;
err = cbs_jpeg_read_scan_header(ctx, &gbc, &scan->header);
if (err < 0)
return err;
pos = get_bits_count(&gbc);
av_assert0(pos % 8 == 0);
if (pos > 0) {
scan->data_size = unit->data_size - pos / 8;
scan->data_ref = av_buffer_ref(unit->data_ref);
if (!scan->data_ref)
return AVERROR(ENOMEM);
scan->data = unit->data + pos / 8;
}
} else {
switch (unit->type) {
#define SEGMENT(marker, type, func, free) \
case JPEG_MARKER_ ## marker: \
{ \
err = ff_cbs_alloc_unit_content(ctx, unit, \
sizeof(type), free); \
if (err < 0) \
return err; \
err = cbs_jpeg_read_ ## func(ctx, &gbc, unit->content); \
if (err < 0) \
return err; \
} \
break
SEGMENT(DQT, JPEGRawQuantisationTableSpecification, dqt, NULL);
SEGMENT(DHT, JPEGRawHuffmanTableSpecification, dht, NULL);
SEGMENT(COM, JPEGRawComment, comment, &cbs_jpeg_free_comment);
#undef SEGMENT
default:
return AVERROR(ENOSYS);
}
}
return 0;
}
static int cbs_jpeg_write_scan(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
JPEGRawScan *scan = unit->content;
int i, err;
err = cbs_jpeg_write_scan_header(ctx, pbc, &scan->header);
if (err < 0)
return err;
if (scan->data) {
if (scan->data_size * 8 > put_bits_left(pbc))
return AVERROR(ENOSPC);
for (i = 0; i < scan->data_size; i++)
put_bits(pbc, 8, scan->data[i]);
}
return 0;
}
static int cbs_jpeg_write_segment(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
int err;
if (unit->type >= JPEG_MARKER_SOF0 &&
unit->type <= JPEG_MARKER_SOF3) {
err = cbs_jpeg_write_frame_header(ctx, pbc, unit->content);
} else if (unit->type >= JPEG_MARKER_APPN &&
unit->type <= JPEG_MARKER_APPN + 15) {
err = cbs_jpeg_write_application_data(ctx, pbc, unit->content);
} else {
switch (unit->type) {
#define SEGMENT(marker, func) \
case JPEG_MARKER_ ## marker: \
err = cbs_jpeg_write_ ## func(ctx, pbc, unit->content); \
break;
SEGMENT(DQT, dqt);
SEGMENT(DHT, dht);
SEGMENT(COM, comment);
default:
return AVERROR_PATCHWELCOME;
}
}
return err;
}
static int cbs_jpeg_write_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
CodedBitstreamJPEGContext *priv = ctx->priv_data;
PutBitContext pbc;
int err;
if (!priv->write_buffer) {
// Initial write buffer size is 1MB.
priv->write_buffer_size = 1024 * 1024;
reallocate_and_try_again:
err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
if (err < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
"sufficiently large write buffer (last attempt "
"%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
return err;
}
}
init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
if (unit->type == JPEG_MARKER_SOS)
err = cbs_jpeg_write_scan(ctx, unit, &pbc);
else
err = cbs_jpeg_write_segment(ctx, unit, &pbc);
if (err == AVERROR(ENOSPC)) {
// Overflow.
priv->write_buffer_size *= 2;
goto reallocate_and_try_again;
}
if (err < 0) {
// Write failed for some other reason.
return err;
}
if (put_bits_count(&pbc) % 8)
unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
else
unit->data_bit_padding = 0;
unit->data_size = (put_bits_count(&pbc) + 7) / 8;
flush_put_bits(&pbc);
err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
if (err < 0)
return err;
memcpy(unit->data, priv->write_buffer, unit->data_size);
return 0;
}
static int cbs_jpeg_assemble_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
const CodedBitstreamUnit *unit;
uint8_t *data;
size_t size, dp, sp;
int i;
size = 4; // SOI + EOI.
for (i = 0; i < frag->nb_units; i++) {
unit = &frag->units[i];
size += 2 + unit->data_size;
if (unit->type == JPEG_MARKER_SOS) {
for (sp = 0; sp < unit->data_size; sp++) {
if (unit->data[sp] == 0xff)
++size;
}
}
}
frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!frag->data_ref)
return AVERROR(ENOMEM);
data = frag->data_ref->data;
dp = 0;
data[dp++] = 0xff;
data[dp++] = JPEG_MARKER_SOI;
for (i = 0; i < frag->nb_units; i++) {
unit = &frag->units[i];
data[dp++] = 0xff;
data[dp++] = unit->type;
if (unit->type != JPEG_MARKER_SOS) {
memcpy(data + dp, unit->data, unit->data_size);
dp += unit->data_size;
} else {
sp = AV_RB16(unit->data);
av_assert0(sp <= unit->data_size);
memcpy(data + dp, unit->data, sp);
dp += sp;
for (; sp < unit->data_size; sp++) {
if (unit->data[sp] == 0xff) {
data[dp++] = 0xff;
data[dp++] = 0x00;
} else {
data[dp++] = unit->data[sp];
}
}
}
}
data[dp++] = 0xff;
data[dp++] = JPEG_MARKER_EOI;
av_assert0(dp == size);
memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
frag->data = data;
frag->data_size = size;
return 0;
}
static void cbs_jpeg_close(CodedBitstreamContext *ctx)
{
CodedBitstreamJPEGContext *priv = ctx->priv_data;
av_freep(&priv->write_buffer);
}
const CodedBitstreamType ff_cbs_type_jpeg = {
.codec_id = AV_CODEC_ID_MJPEG,
.priv_data_size = sizeof(CodedBitstreamJPEGContext),
.split_fragment = &cbs_jpeg_split_fragment,
.read_unit = &cbs_jpeg_read_unit,
.write_unit = &cbs_jpeg_write_unit,
.assemble_fragment = &cbs_jpeg_assemble_fragment,
.close = &cbs_jpeg_close,
};
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