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avformat/vorbiscomment: use null buf to calculate vorbis comment length

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Also check possible failures when calculating length, and change return type to
int as bigger return values are no longer possible.
This commit is contained in:
Marton Balint
2025-12-23 02:52:59 +01:00
parent c80d3b35ae
commit b2e077ad69
5 changed files with 27 additions and 25 deletions
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4
libavformat/flacenc.c
View File

@@ -64,11 +64,13 @@ static int flac_write_block_comment(AVIOContext *pb, AVDictionary **m,
int last_block, int bitexact)
{
const char *vendor = bitexact ? "ffmpeg" : LIBAVFORMAT_IDENT;
int64_t len;
int len;
ff_metadata_conv(m, ff_vorbiscomment_metadata_conv, NULL);
len = ff_vorbiscomment_length(*m, vendor, NULL, 0);
if (len < 0)
return len;
if (len >= ((1<<24) - 4))
return AVERROR(EINVAL);

4
libavformat/matroskaenc.c
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@@ -1061,12 +1061,14 @@ static int put_flac_codecpriv(AVFormatContext *s, AVIOContext *pb,
"Lavf" : LIBAVFORMAT_IDENT;
AVDictionary *dict = NULL;
uint8_t buf[32];
int64_t len;
int len;
snprintf(buf, sizeof(buf), "0x%"PRIx64, par->ch_layout.u.mask);
av_dict_set(&dict, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", buf, 0);
len = ff_vorbiscomment_length(dict, vendor, NULL, 0);
if (len < 0)
return len;
av_assert1(len < (1 << 24) - 4);
avio_w8(pb, 0x84);

5
libavformat/oggenc.c
View File

@@ -295,7 +295,10 @@ static uint8_t *ogg_write_vorbiscomment(int64_t offset, int bitexact,
ff_metadata_conv(m, ff_vorbiscomment_metadata_conv, NULL);
size = offset + ff_vorbiscomment_length(*m, vendor, chapters, nb_chapters) + framing_bit;
size = ff_vorbiscomment_length(*m, vendor, chapters, nb_chapters);
if (size < 0)
return NULL;
size += offset + framing_bit;
if (size > INT_MAX)
return NULL;
p = av_mallocz(size);

35
libavformat/vorbiscomment.c
View File

@@ -20,6 +20,7 @@
*/
#include "avio.h"
#include "avio_internal.h"
#include "avformat.h"
#include "metadata.h"
#include "vorbiscomment.h"
@@ -38,27 +39,21 @@ const AVMetadataConv ff_vorbiscomment_metadata_conv[] = {
{ 0 }
};
int64_t ff_vorbiscomment_length(const AVDictionary *m, const char *vendor_string,
AVChapter **chapters, unsigned int nb_chapters)
int ff_vorbiscomment_length(const AVDictionary *m, const char *vendor_string,
AVChapter **chapters, unsigned int nb_chapters)
{
int64_t len = 8;
len += strlen(vendor_string);
if (chapters && nb_chapters) {
for (int i = 0; i < nb_chapters; i++) {
const AVDictionaryEntry *tag = NULL;
len += 4 + 12 + 1 + 10;
while ((tag = av_dict_iterate(chapters[i]->metadata, tag))) {
int64_t len1 = !strcmp(tag->key, "title") ? 4 : strlen(tag->key);
len += 4 + 10 + len1 + 1 + strlen(tag->value);
}
}
}
if (m) {
const AVDictionaryEntry *tag = NULL;
while ((tag = av_dict_iterate(m, tag))) {
len += 4 +strlen(tag->key) + 1 + strlen(tag->value);
}
}
AVIOContext *avio_buf;
int ret, len;
ret = ffio_open_null_buf(&avio_buf);
if (ret < 0)
return ret;
ret = ff_vorbiscomment_write(avio_buf, m, vendor_string, chapters, nb_chapters);
len = ffio_close_null_buf(avio_buf);
if (ret < 0)
return ret;
return len;
}

4
libavformat/vorbiscomment.h
View File

@@ -34,8 +34,8 @@
* For no string, set to an empty string.
* @return The length in bytes.
*/
int64_t ff_vorbiscomment_length(const AVDictionary *m, const char *vendor_string,
AVChapter **chapters, unsigned int nb_chapters);
int ff_vorbiscomment_length(const AVDictionary *m, const char *vendor_string,
AVChapter **chapters, unsigned int nb_chapters);
/**
* Write a VorbisComment into an AVIOContext. The output size can be obtained