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Reduce memory reallocation when rendering an ID3v2 tag.

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Prevent an ID3v2 padding from being ridiculously large.
This commit is contained in:
Tsuda Kageyu 2015-11-13 11:35:37 +09:00
parent c353a71ce5
commit 091ab9dee0
1 changed files with 29 additions and 16 deletions
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45
taglib/mpeg/id3v2/id3v2tag.cpp
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@ -27,6 +27,8 @@
#include "config.h"
#endif
#include <algorithm>
#include "tfile.h"
#include "id3v2tag.h"
@ -86,7 +88,8 @@ const ID3v2::Latin1StringHandler *ID3v2::Tag::TagPrivate::stringHandler = &defau
namespace
{
const TagLib::uint DefaultPaddingSize = 1024;
const long MinPaddingSize = 1024;
const long MaxPaddingSize = 1024 * 1024;
}
////////////////////////////////////////////////////////////////////////////////
@ -569,8 +572,6 @@ ByteVector ID3v2::Tag::render(int version) const
// in ID3v2::Header::tagSize() -- includes the extended header, frames and
// padding, but does not include the tag's header or footer.
ByteVector tagData;
if(version != 3 && version != 4) {
debug("Unknown ID3v2 version, using ID3v2.4");
version = 4;
@ -578,7 +579,7 @@ ByteVector ID3v2::Tag::render(int version) const
// TODO: Render the extended header.
// Loop through the frames rendering them and adding them to the tagData.
// Downgrade the frames that ID3v2.3 doesn't support.
FrameList newFrames;
newFrames.setAutoDelete(true);
@ -591,6 +592,12 @@ ByteVector ID3v2::Tag::render(int version) const
downgradeFrames(&frameList, &newFrames);
}
// Reserve a 10-byte blank space for an ID3v2 tag header.
ByteVector tagData(Header::size(), '\0');
// Loop through the frames rendering them and adding them to the tagData.
for(FrameList::ConstIterator it = frameList.begin(); it != frameList.end(); it++) {
(*it)->header()->setVersion(version);
if((*it)->header()->frameID().size() != 4) {
@ -610,29 +617,35 @@ ByteVector ID3v2::Tag::render(int version) const
}
// Compute the amount of padding, and append that to tagData.
// TODO: Should be calculated in offset_t in taglib2.
uint paddingSize = DefaultPaddingSize;
long paddingSize = d->header.tagSize() - tagData.size();
if(d->file && tagData.size() < d->header.tagSize()) {
paddingSize = d->header.tagSize() - tagData.size();
if(paddingSize <= 0) {
paddingSize = MinPaddingSize;
}
else {
// Padding won't increase beyond 1% of the file size or 1MB.
// Padding won't increase beyond 1% of the file size.
long threshold = d->file ? d->file->length() / 100 : 0;
threshold = std::max(threshold, MinPaddingSize);
threshold = std::min(threshold, MaxPaddingSize);
if(paddingSize > DefaultPaddingSize) {
const uint threshold = d->file->length() / 100; // should be ulonglong in taglib2.
if(paddingSize > threshold)
paddingSize = DefaultPaddingSize;
}
if(paddingSize > threshold)
paddingSize = MinPaddingSize;
}
tagData.append(ByteVector(paddingSize, '\0'));
tagData.resize(static_cast<uint>(tagData.size() + paddingSize), '\0');
// Set the version and data size.
d->header.setMajorVersion(version);
d->header.setTagSize(tagData.size());
d->header.setTagSize(tagData.size() - Header::size());
// TODO: This should eventually include d->footer->render().
return d->header.render() + tagData;
const ByteVector headerData = d->header.render();
std::copy(headerData.begin(), headerData.end(), tagData.begin());
return tagData;
}
Latin1StringHandler const *ID3v2::Tag::latin1StringHandler()