| // Copyright 2015 PDFium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com |
| |
| #include "core/fxcodec/jbig2/JBig2_BitStream.h" |
| |
| #include <algorithm> |
| |
| #include "third_party/base/numerics/safe_conversions.h" |
| |
| namespace { |
| |
| pdfium::span<const uint8_t> ValidatedSpan(pdfium::span<const uint8_t> sp) { |
| if (sp.size() > 256 * 1024 * 1024) |
| return {}; |
| return sp; |
| } |
| |
| } // namespace |
| |
| CJBig2_BitStream::CJBig2_BitStream(pdfium::span<const uint8_t> pSrcStream, |
| uint64_t key) |
| : m_Span(ValidatedSpan(pSrcStream)), m_Key(key) {} |
| |
| CJBig2_BitStream::~CJBig2_BitStream() = default; |
| |
| int32_t CJBig2_BitStream::readNBits(uint32_t dwBits, uint32_t* dwResult) { |
| if (!IsInBounds()) |
| return -1; |
| |
| uint32_t dwBitPos = getBitPos(); |
| if (dwBitPos > LengthInBits()) |
| return -1; |
| |
| *dwResult = 0; |
| if (dwBitPos + dwBits <= LengthInBits()) |
| dwBitPos = dwBits; |
| else |
| dwBitPos = LengthInBits() - dwBitPos; |
| |
| for (; dwBitPos > 0; --dwBitPos) { |
| *dwResult = |
| (*dwResult << 1) | ((m_Span[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01); |
| AdvanceBit(); |
| } |
| return 0; |
| } |
| |
| int32_t CJBig2_BitStream::readNBits(uint32_t dwBits, int32_t* nResult) { |
| if (!IsInBounds()) |
| return -1; |
| |
| uint32_t dwBitPos = getBitPos(); |
| if (dwBitPos > LengthInBits()) |
| return -1; |
| |
| *nResult = 0; |
| if (dwBitPos + dwBits <= LengthInBits()) |
| dwBitPos = dwBits; |
| else |
| dwBitPos = LengthInBits() - dwBitPos; |
| |
| for (; dwBitPos > 0; --dwBitPos) { |
| *nResult = |
| (*nResult << 1) | ((m_Span[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01); |
| AdvanceBit(); |
| } |
| return 0; |
| } |
| |
| int32_t CJBig2_BitStream::read1Bit(uint32_t* dwResult) { |
| if (!IsInBounds()) |
| return -1; |
| |
| *dwResult = (m_Span[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01; |
| AdvanceBit(); |
| return 0; |
| } |
| |
| int32_t CJBig2_BitStream::read1Bit(bool* bResult) { |
| if (!IsInBounds()) |
| return -1; |
| |
| *bResult = (m_Span[m_dwByteIdx] >> (7 - m_dwBitIdx)) & 0x01; |
| AdvanceBit(); |
| return 0; |
| } |
| |
| int32_t CJBig2_BitStream::read1Byte(uint8_t* cResult) { |
| if (!IsInBounds()) |
| return -1; |
| |
| *cResult = m_Span[m_dwByteIdx]; |
| ++m_dwByteIdx; |
| return 0; |
| } |
| |
| int32_t CJBig2_BitStream::readInteger(uint32_t* dwResult) { |
| if (m_dwByteIdx + 3 >= m_Span.size()) |
| return -1; |
| |
| *dwResult = (m_Span[m_dwByteIdx] << 24) | (m_Span[m_dwByteIdx + 1] << 16) | |
| (m_Span[m_dwByteIdx + 2] << 8) | m_Span[m_dwByteIdx + 3]; |
| m_dwByteIdx += 4; |
| return 0; |
| } |
| |
| int32_t CJBig2_BitStream::readShortInteger(uint16_t* dwResult) { |
| if (m_dwByteIdx + 1 >= m_Span.size()) |
| return -1; |
| |
| *dwResult = (m_Span[m_dwByteIdx] << 8) | m_Span[m_dwByteIdx + 1]; |
| m_dwByteIdx += 2; |
| return 0; |
| } |
| |
| void CJBig2_BitStream::alignByte() { |
| if (m_dwBitIdx != 0) { |
| ++m_dwByteIdx; |
| m_dwBitIdx = 0; |
| } |
| } |
| |
| uint8_t CJBig2_BitStream::getCurByte() const { |
| return IsInBounds() ? m_Span[m_dwByteIdx] : 0; |
| } |
| |
| void CJBig2_BitStream::incByteIdx() { |
| if (IsInBounds()) |
| ++m_dwByteIdx; |
| } |
| |
| uint8_t CJBig2_BitStream::getCurByte_arith() const { |
| return IsInBounds() ? m_Span[m_dwByteIdx] : 0xFF; |
| } |
| |
| uint8_t CJBig2_BitStream::getNextByte_arith() const { |
| return m_dwByteIdx + 1 < m_Span.size() ? m_Span[m_dwByteIdx + 1] : 0xFF; |
| } |
| |
| uint32_t CJBig2_BitStream::getOffset() const { |
| return m_dwByteIdx; |
| } |
| |
| void CJBig2_BitStream::setOffset(uint32_t dwOffset) { |
| m_dwByteIdx = std::min(dwOffset, getLength()); |
| } |
| |
| uint32_t CJBig2_BitStream::getBitPos() const { |
| return (m_dwByteIdx << 3) + m_dwBitIdx; |
| } |
| |
| void CJBig2_BitStream::setBitPos(uint32_t dwBitPos) { |
| m_dwByteIdx = dwBitPos >> 3; |
| m_dwBitIdx = dwBitPos & 7; |
| } |
| |
| const uint8_t* CJBig2_BitStream::getBuf() const { |
| return m_Span.data(); |
| } |
| |
| uint32_t CJBig2_BitStream::getLength() const { |
| return pdfium::base::checked_cast<uint32_t>(m_Span.size()); |
| } |
| |
| const uint8_t* CJBig2_BitStream::getPointer() const { |
| return getBuf() + m_dwByteIdx; |
| } |
| |
| void CJBig2_BitStream::offset(uint32_t dwOffset) { |
| m_dwByteIdx += dwOffset; |
| } |
| |
| uint32_t CJBig2_BitStream::getByteLeft() const { |
| return getLength() - m_dwByteIdx; |
| } |
| |
| void CJBig2_BitStream::AdvanceBit() { |
| if (m_dwBitIdx == 7) { |
| ++m_dwByteIdx; |
| m_dwBitIdx = 0; |
| } else { |
| ++m_dwBitIdx; |
| } |
| } |
| |
| bool CJBig2_BitStream::IsInBounds() const { |
| return m_dwByteIdx < getLength(); |
| } |
| |
| uint32_t CJBig2_BitStream::LengthInBits() const { |
| return getLength() << 3; |
| } |