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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mp4_demuxer/Box.h"
#include "mp4_demuxer/Stream.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/Unused.h"
#include <algorithm>
using namespace mozilla;
namespace mp4_demuxer {
// Limit reads to 32MiB max.
// static
const uint64_t Box::kMAX_BOX_READ = 32 * 1024 * 1024;
// Returns the offset from the start of the body of a box of type |aType|
// to the start of its first child.
static uint32_t
BoxOffset(AtomType aType)
{
const uint32_t FULLBOX_OFFSET = 4;
if (aType == AtomType("mp4a") || aType == AtomType("enca")) {
// AudioSampleEntry; ISO 14496-12, section 8.16
return 28;
} else if (aType == AtomType("mp4v") || aType == AtomType("encv")) {
// VideoSampleEntry; ISO 14496-12, section 8.16
return 78;
} else if (aType == AtomType("stsd")) {
// SampleDescriptionBox; ISO 14496-12, section 8.16
// This is a FullBox, and contains a |count| member before its child
// boxes.
return FULLBOX_OFFSET + 4;
}
return 0;
}
Box::Box(BoxContext* aContext, uint64_t aOffset, const Box* aParent)
: mContext(aContext), mParent(aParent)
{
uint8_t header[8];
if (aOffset > INT64_MAX - sizeof(header)) {
return;
}
MediaByteRange headerRange(aOffset, aOffset + sizeof(header));
if (mParent && !mParent->mRange.Contains(headerRange)) {
return;
}
const MediaByteRange* byteRange;
for (int i = 0; ; i++) {
if (i == mContext->mByteRanges.Length()) {
return;
}
byteRange = static_cast<const MediaByteRange*>(&mContext->mByteRanges[i]);
if (byteRange->Contains(headerRange)) {
break;
}
}
size_t bytes;
if (!mContext->mSource->CachedReadAt(aOffset, header, sizeof(header),
&bytes) ||
bytes != sizeof(header)) {
return;
}
uint64_t size = BigEndian::readUint32(header);
if (size == 1) {
uint8_t bigLength[8];
if (aOffset > INT64_MAX - sizeof(header) - sizeof(bigLength)) {
return;
}
MediaByteRange bigLengthRange(headerRange.mEnd,
headerRange.mEnd + sizeof(bigLength));
if ((mParent && !mParent->mRange.Contains(bigLengthRange)) ||
!byteRange->Contains(bigLengthRange) ||
!mContext->mSource->CachedReadAt(aOffset + sizeof(header), bigLength,
sizeof(bigLength), &bytes) ||
bytes != sizeof(bigLength)) {
return;
}
size = BigEndian::readUint64(bigLength);
mBodyOffset = bigLengthRange.mEnd;
} else if (size == 0) {
// box extends to end of file.
size = mContext->mByteRanges.LastInterval().mEnd - aOffset;
mBodyOffset = headerRange.mEnd;
} else {
mBodyOffset = headerRange.mEnd;
}
if (size > INT64_MAX) {
return;
}
int64_t end = static_cast<int64_t>(aOffset) + static_cast<int64_t>(size);
if (end < static_cast<int64_t>(aOffset)) {
// Overflowed.
return;
}
mType = BigEndian::readUint32(&header[4]);
mChildOffset = mBodyOffset + BoxOffset(mType);
MediaByteRange boxRange(aOffset, end);
if (mChildOffset > boxRange.mEnd ||
(mParent && !mParent->mRange.Contains(boxRange)) ||
!byteRange->Contains(boxRange)) {
return;
}
mRange = boxRange;
}
Box::Box()
: mContext(nullptr)
{}
Box
Box::Next() const
{
MOZ_ASSERT(IsAvailable());
return Box(mContext, mRange.mEnd, mParent);
}
Box
Box::FirstChild() const
{
MOZ_ASSERT(IsAvailable());
if (mChildOffset == mRange.mEnd) {
return Box();
}
return Box(mContext, mChildOffset, this);
}
nsTArray<uint8_t>
Box::Read()
{
nsTArray<uint8_t> out;
Unused << Read(&out, mRange);
return out;
}
bool
Box::Read(nsTArray<uint8_t>* aDest, const MediaByteRange& aRange)
{
int64_t length;
if (!mContext->mSource->Length(&length)) {
// The HTTP server didn't give us a length to work with.
// Limit the read to kMAX_BOX_READ max.
length = std::min(aRange.mEnd - mChildOffset, kMAX_BOX_READ);
} else {
length = aRange.mEnd - mChildOffset;
}
aDest->SetLength(length);
size_t bytes;
if (!mContext->mSource->CachedReadAt(mChildOffset, aDest->Elements(),
aDest->Length(), &bytes) ||
bytes != aDest->Length()) {
// Byte ranges are being reported incorrectly
NS_WARNING("Read failed in mp4_demuxer::Box::Read()");
aDest->Clear();
return false;
}
return true;
}
}
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