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preserve the extra data after the comments

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This commit is contained in:
Frédéric Mangano-Tarumi 2018-11-06 18:46:40 -05:00
parent bd50fb34d9
commit 0df7514a83
3 changed files with 34 additions and 6 deletions
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11
src/opus.cc
View File

@ -34,6 +34,9 @@
#define le32toh(x) OSSwapLittleToHostInt32(x)
#endif
/**
* \todo Use RAII. Here the allocated objects are not even properly freed on error.
*/
int ot::parse_tags(const char *data, long len, opus_tags *tags)
{
long pos;
@ -70,10 +73,8 @@ int ot::parse_tags(const char *data, long len, opus_tags *tags)
if (pos > len)
return -1;
}
if (pos < len)
fprintf(stderr, "warning: %ld unused bytes at the end of the OpusTags packet\n", len - pos);
// Extra data
tags->extra_data = ot::string_view{data + pos, static_cast<size_t>(len - pos)};
return 0;
}
@ -88,6 +89,7 @@ int ot::render_tags(opus_tags *tags, ogg_packet *op)
uint32_t i;
for (i=0; i<tags->count; i++)
len += 4 + tags->lengths[i];
len += tags->extra_data.size;
op->bytes = len;
char *data = static_cast<char*>(malloc(len));
if (!data)
@ -108,6 +110,7 @@ int ot::render_tags(opus_tags *tags, ogg_packet *op)
memcpy(data+4, tags->comment[i], tags->lengths[i]);
data += 4 + tags->lengths[i];
}
memcpy(data, tags->extra_data.data, tags->extra_data.size);
return 0;
}

22
src/opustags.h
View File

@ -9,6 +9,14 @@
namespace ot {
/**
* Non-owning string, similar to what std::string_view is in C++17.
*/
struct string_view {
const char *data;
size_t size;
};
/**
* \defgroup ogg Ogg
* \brief Helpers to work with libogg.
@ -29,8 +37,6 @@ int write_page(ogg_page *og, FILE *stream);
/**
* Represent all the data in an OpusTags packet.
*
* \todo The comment list may be followed by arbitrary binary data, which we should keep here.
*/
struct opus_tags {
uint32_t vendor_length;
@ -38,6 +44,18 @@ struct opus_tags {
uint32_t count;
uint32_t *lengths;
const char **comment;
/**
* According to RFC 7845:
* > Immediately following the user comment list, the comment header MAY contain
* > zero-padding or other binary data that is not specified here.
*
* The first byte is supposed to indicate whether this data should be kept or not, but let's
* assume it's here for a reason and always keep it. Better safe than sorry.
*
* In the future, we could add options to manipulate this data: view it, edit it, truncate
* it if it's marked as padding, truncate it unconditionally.
*/
string_view extra_data;
};
int parse_tags(const char *data, long len, opus_tags *tags);

7
t/unit.cc
View File

@ -54,6 +54,8 @@ static bool parse_standard()
throw failure("bad title comment");
if (memcmp(tags.comment[1], "ARTIST=Bar", tags.lengths[1]) != 0)
throw failure("bad artist comment");
if (tags.extra_data.size != 0)
throw failure("found mysterious padding data");
ot::free_tags(&tags);
return true;
}
@ -94,6 +96,11 @@ static bool recode_padding()
int rc = ot::parse_tags(padded_OpusTags.data(), padded_OpusTags.size(), &tags);
if (rc != 0)
throw failure("ot::parse_tags did not return 0");
if (tags.extra_data.size != 6)
throw failure("unexpected amount of extra bytes");
if (memcmp(tags.extra_data.data, "\0hello", 6) != 0)
throw failure("corrupted extra data");
// recode the packet and ensure it's exactly the same
ogg_packet packet;
rc = ot::render_tags(&tags, &packet);
if (packet.bytes < padded_OpusTags.size())