Add m-esr52 at 52.6.0

1 files changed, 331 insertions, 0 deletions

diff --git a/image/decoders/EXIF.cpp b/image/decoders/EXIF.cpp
new file mode 100644
index 000000000..8197c886c
--- /dev/null
+++ b/image/decoders/EXIF.cpp
@@ -0,0 +1,331 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "EXIF.h"
+
+#include "mozilla/EndianUtils.h"
+
+namespace mozilla {
+namespace image {
+
+// Section references in this file refer to the EXIF v2.3 standard, also known
+// as CIPA DC-008-Translation-2010.
+
+// See Section 4.6.4, Table 4.
+// Typesafe enums are intentionally not used here since we're comparing to raw
+// integers produced by parsing.
+enum EXIFTag
+{
+  OrientationTag = 0x112,
+};
+
+// See Section 4.6.2.
+enum EXIFType
+{
+  ByteType       = 1,
+  ASCIIType      = 2,
+  ShortType      = 3,
+  LongType       = 4,
+  RationalType   = 5,
+  UndefinedType  = 7,
+  SignedLongType = 9,
+  SignedRational = 10,
+};
+
+static const char* EXIFHeader = "Exif\0\0";
+static const uint32_t EXIFHeaderLength = 6;
+
+/////////////////////////////////////////////////////////////
+// Parse EXIF data, typically found in a JPEG's APP1 segment.
+/////////////////////////////////////////////////////////////
+EXIFData
+EXIFParser::ParseEXIF(const uint8_t* aData, const uint32_t aLength)
+{
+  if (!Initialize(aData, aLength)) {
+    return EXIFData();
+  }
+
+  if (!ParseEXIFHeader()) {
+    return EXIFData();
+  }
+
+  uint32_t offsetIFD;
+  if (!ParseTIFFHeader(offsetIFD)) {
+    return EXIFData();
+  }
+
+  JumpTo(offsetIFD);
+
+  Orientation orientation;
+  if (!ParseIFD0(orientation)) {
+    return EXIFData();
+  }
+
+  // We only care about orientation at this point, so we don't bother with the
+  // other IFDs. If we got this far we're done.
+  return EXIFData(orientation);
+}
+
+/////////////////////////////////////////////////////////
+// Parse the EXIF header. (Section 4.7.2, Figure 30)
+/////////////////////////////////////////////////////////
+bool
+EXIFParser::ParseEXIFHeader()
+{
+  return MatchString(EXIFHeader, EXIFHeaderLength);
+}
+
+/////////////////////////////////////////////////////////
+// Parse the TIFF header. (Section 4.5.2, Table 1)
+/////////////////////////////////////////////////////////
+bool
+EXIFParser::ParseTIFFHeader(uint32_t& aIFD0OffsetOut)
+{
+  // Determine byte order.
+  if (MatchString("MM\0*", 4)) {
+    mByteOrder = ByteOrder::BigEndian;
+  } else if (MatchString("II*\0", 4)) {
+    mByteOrder = ByteOrder::LittleEndian;
+  } else {
+    return false;
+  }
+
+  // Determine offset of the 0th IFD. (It shouldn't be greater than 64k, which
+  // is the maximum size of the entry APP1 segment.)
+  uint32_t ifd0Offset;
+  if (!ReadUInt32(ifd0Offset) || ifd0Offset > 64 * 1024) {
+    return false;
+  }
+
+  // The IFD offset is relative to the beginning of the TIFF header, which
+  // begins after the EXIF header, so we need to increase the offset
+  // appropriately.
+  aIFD0OffsetOut = ifd0Offset + EXIFHeaderLength;
+  return true;
+}
+
+/////////////////////////////////////////////////////////
+// Parse the entries in IFD0. (Section 4.6.2)
+/////////////////////////////////////////////////////////
+bool
+EXIFParser::ParseIFD0(Orientation& aOrientationOut)
+{
+  uint16_t entryCount;
+  if (!ReadUInt16(entryCount)) {
+    return false;
+  }
+
+  for (uint16_t entry = 0 ; entry < entryCount ; ++entry) {
+    // Read the fields of the entry.
+    uint16_t tag;
+    if (!ReadUInt16(tag)) {
+      return false;
+    }
+
+    // Right now, we only care about orientation, so we immediately skip to the
+    // next entry if we find anything else.
+    if (tag != OrientationTag) {
+      Advance(10);
+      continue;
+    }
+
+    uint16_t type;
+    if (!ReadUInt16(type)) {
+      return false;
+    }
+
+    uint32_t count;
+    if (!ReadUInt32(count)) {
+      return false;
+    }
+
+    // We should have an orientation value here; go ahead and parse it.
+    if (!ParseOrientation(type, count, aOrientationOut)) {
+      return false;
+    }
+
+    // Since the orientation is all we care about, we're done.
+    return true;
+  }
+
+  // We didn't find an orientation field in the IFD. That's OK; we assume the
+  // default orientation in that case.
+  aOrientationOut = Orientation();
+  return true;
+}
+
+bool
+EXIFParser::ParseOrientation(uint16_t aType, uint32_t aCount, Orientation& aOut)
+{
+  // Sanity check the type and count.
+  if (aType != ShortType || aCount != 1) {
+    return false;
+  }
+
+  uint16_t value;
+  if (!ReadUInt16(value)) {
+    return false;
+  }
+
+  switch (value) {
+    case 1: aOut = Orientation(Angle::D0,   Flip::Unflipped);  break;
+    case 2: aOut = Orientation(Angle::D0,   Flip::Horizontal); break;
+    case 3: aOut = Orientation(Angle::D180, Flip::Unflipped);  break;
+    case 4: aOut = Orientation(Angle::D180, Flip::Horizontal); break;
+    case 5: aOut = Orientation(Angle::D90,  Flip::Horizontal); break;
+    case 6: aOut = Orientation(Angle::D90,  Flip::Unflipped);  break;
+    case 7: aOut = Orientation(Angle::D270, Flip::Horizontal); break;
+    case 8: aOut = Orientation(Angle::D270, Flip::Unflipped);  break;
+    default: return false;
+  }
+
+  // This is a 32-bit field, but the orientation value only occupies the first
+  // 16 bits. We need to advance another 16 bits to consume the entire field.
+  Advance(2);
+  return true;
+}
+
+bool
+EXIFParser::Initialize(const uint8_t* aData, const uint32_t aLength)
+{
+  if (aData == nullptr) {
+    return false;
+  }
+
+  // An APP1 segment larger than 64k violates the JPEG standard.
+  if (aLength > 64 * 1024) {
+    return false;
+  }
+
+  mStart = mCurrent = aData;
+  mLength = mRemainingLength = aLength;
+  mByteOrder = ByteOrder::Unknown;
+  return true;
+}
+
+void
+EXIFParser::Advance(const uint32_t aDistance)
+{
+  if (mRemainingLength >= aDistance) {
+    mCurrent += aDistance;
+    mRemainingLength -= aDistance;
+  } else {
+    mCurrent = mStart;
+    mRemainingLength = 0;
+  }
+}
+
+void
+EXIFParser::JumpTo(const uint32_t aOffset)
+{
+  if (mLength >= aOffset) {
+    mCurrent = mStart + aOffset;
+    mRemainingLength = mLength - aOffset;
+  } else {
+    mCurrent = mStart;
+    mRemainingLength = 0;
+  }
+}
+
+bool
+EXIFParser::MatchString(const char* aString, const uint32_t aLength)
+{
+  if (mRemainingLength < aLength) {
+    return false;
+  }
+
+  for (uint32_t i = 0 ; i < aLength ; ++i) {
+    if (mCurrent[i] != aString[i]) {
+      return false;
+    }
+  }
+
+  Advance(aLength);
+  return true;
+}
+
+bool
+EXIFParser::MatchUInt16(const uint16_t aValue)
+{
+  if (mRemainingLength < 2) {
+    return false;
+  }
+
+  bool matched;
+  switch (mByteOrder) {
+    case ByteOrder::LittleEndian:
+      matched = LittleEndian::readUint16(mCurrent) == aValue;
+      break;
+    case ByteOrder::BigEndian:
+      matched = BigEndian::readUint16(mCurrent) == aValue;
+      break;
+    default:
+      NS_NOTREACHED("Should know the byte order by now");
+      matched = false;
+  }
+
+  if (matched) {
+    Advance(2);
+  }
+
+  return matched;
+}
+
+bool
+EXIFParser::ReadUInt16(uint16_t& aValue)
+{
+  if (mRemainingLength < 2) {
+    return false;
+  }
+
+  bool matched = true;
+  switch (mByteOrder) {
+    case ByteOrder::LittleEndian:
+      aValue = LittleEndian::readUint16(mCurrent);
+      break;
+    case ByteOrder::BigEndian:
+      aValue = BigEndian::readUint16(mCurrent);
+      break;
+    default:
+      NS_NOTREACHED("Should know the byte order by now");
+      matched = false;
+  }
+
+  if (matched) {
+    Advance(2);
+  }
+
+  return matched;
+}
+
+bool
+EXIFParser::ReadUInt32(uint32_t& aValue)
+{
+  if (mRemainingLength < 4) {
+    return false;
+  }
+
+  bool matched = true;
+  switch (mByteOrder) {
+    case ByteOrder::LittleEndian:
+      aValue = LittleEndian::readUint32(mCurrent);
+      break;
+    case ByteOrder::BigEndian:
+      aValue = BigEndian::readUint32(mCurrent);
+      break;
+    default:
+      NS_NOTREACHED("Should know the byte order by now");
+      matched = false;
+  }
+
+  if (matched) {
+    Advance(4);
+  }
+
+  return matched;
+}
+
+} // namespace image
+} // namespace mozilla