| // Copyright 2016 The Tulsi Authors. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef POST_PROCESSOR_DWARFBUFFERREADER_H_ |
| #define POST_PROCESSOR_DWARFBUFFERREADER_H_ |
| |
| #include <cassert> |
| #include <string> |
| |
| namespace post_processor { |
| |
| /// Provides basic functions to manage a byte buffer as a collection of |
| /// DWARF-style primitives (e.g., ULEB128-encoded values, QWORDS, etc...). |
| class DWARFBufferReader { |
| public: |
| /// WARNING: This class does not take ownership of the given buffer and it is |
| /// the responsibility of the user to ensure that the buffer is valid for the |
| /// life of this instance. |
| DWARFBufferReader(const uint8_t *buffer, |
| size_t buffer_length, |
| bool swap_byte_ordering); |
| |
| inline size_t buffer_length() const { return buffer_length_; } |
| |
| /// The offset to the current read position from the beginning of the buffer. |
| inline size_t read_position() const { return read_ptr_ - buffer_; } |
| |
| inline size_t bytes_remaining() const { |
| if (read_ptr_ >= buffer_end_) { return 0; } |
| return buffer_end_ - read_ptr_; |
| } |
| |
| inline bool ReadByte(uint8_t *byte) { |
| if (bytes_remaining() < 1) { return false; } |
| *byte = *read_ptr_; |
| ++read_ptr_; |
| return true; |
| } |
| |
| bool ReadWORD(uint16_t *); |
| bool ReadDWORD(uint32_t *); |
| bool ReadQWORD(uint64_t *); |
| |
| /// Reads a DWARF Little Endian Base 128-encoded value. |
| bool ReadULEB128(uint64_t *out); |
| |
| /// Copies length characters into the given buffer. |
| inline bool ReadCharacters(char *buffer, size_t length) { |
| assert(buffer); |
| if (length > bytes_remaining()) { return false; } |
| memcpy(buffer, read_ptr_, length); |
| read_ptr_ += length; |
| return true; |
| } |
| |
| /// Reads a null-terminated ASCII string into the given buffer. |
| bool ReadASCIIZ(std::string *out); |
| |
| /// Sets the read pointer to the given offset. No validation is performed so |
| /// care must be taken to ensure that the given offset is not past the end of |
| /// the buffer. |
| inline void SeekToOffset(size_t offset) { read_ptr_ = buffer_ + offset; } |
| |
| /// Advances the read pointer by the given number of bytes. No validation is |
| /// performed so care must be taken to ensure that the pointer is not advanced |
| /// past the end of the buffer. |
| inline void SkipForward(size_t bytes) { read_ptr_ += bytes; } |
| |
| private: |
| uint8_t const *buffer_; |
| size_t buffer_length_; |
| bool swap_byte_ordering_; |
| |
| // Convenience pointer to one byte past the end of the buffer_; |
| uint8_t const *buffer_end_; |
| |
| const uint8_t *read_ptr_; |
| }; |
| |
| } // namespace post_processor |
| |
| #endif // POST_PROCESSOR_DWARFBUFFERREADER_H_ |