| // Copyright 2014 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/big_endian.h" |
| |
| #include <string.h> |
| |
| #include "base/numerics/byte_conversions.h" |
| #include "base/numerics/checked_math.h" |
| #include "base/strings/string_piece.h" |
| |
| namespace base { |
| |
| BigEndianReader BigEndianReader::FromStringPiece( |
| base::StringPiece string_piece) { |
| return BigEndianReader(base::as_byte_span(string_piece)); |
| } |
| |
| BigEndianReader::BigEndianReader(const uint8_t* buf, size_t len) |
| : ptr_(buf), end_(ptr_ + len) { |
| // Ensure `len` does not cause `end_` to wrap around. |
| CHECK_GE(end_, ptr_); |
| } |
| |
| BigEndianReader::BigEndianReader(base::span<const uint8_t> buf) |
| : ptr_(buf.data()), end_(buf.data() + buf.size()) {} |
| |
| bool BigEndianReader::Skip(size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| ptr_ += len; |
| return true; |
| } |
| |
| bool BigEndianReader::ReadBytes(void* out, size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| memcpy(out, ptr_, len); |
| ptr_ += len; |
| return true; |
| } |
| |
| bool BigEndianReader::ReadPiece(base::StringPiece* out, size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| *out = base::StringPiece(reinterpret_cast<const char*>(ptr_), len); |
| ptr_ += len; |
| return true; |
| } |
| |
| bool BigEndianReader::ReadSpan(base::span<const uint8_t>* out, size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| *out = base::make_span(ptr_, len); |
| ptr_ += len; |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU8(uint8_t* value) { |
| std::optional<span<const uint8_t, 1u>> bytes = ReadFixedSpan<1u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U8FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU16(uint16_t* value) { |
| std::optional<span<const uint8_t, 2u>> bytes = ReadFixedSpan<2u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U16FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU32(uint32_t* value) { |
| std::optional<span<const uint8_t, 4u>> bytes = ReadFixedSpan<4u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U32FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU64(uint64_t* value) { |
| std::optional<span<const uint8_t, 8u>> bytes = ReadFixedSpan<8u>(); |
| if (!bytes.has_value()) { |
| return false; |
| } |
| *value = numerics::U64FromBigEndian(*bytes); |
| return true; |
| } |
| |
| bool BigEndianReader::ReadU8LengthPrefixed(std::string_view* out) { |
| uint8_t len; |
| if (!ReadU8(&len)) { |
| return false; |
| } |
| const bool ok = ReadPiece(out, len); |
| if (!ok) { |
| ptr_ -= 1u; // Undo the ReadU8. |
| } |
| return ok; |
| } |
| |
| bool BigEndianReader::ReadU16LengthPrefixed(std::string_view* out) { |
| uint16_t len; |
| if (!ReadU16(&len)) { |
| return false; |
| } |
| const bool ok = ReadPiece(out, len); |
| if (!ok) { |
| ptr_ -= 2u; // Undo the ReadU16. |
| } |
| return ok; |
| } |
| |
| BigEndianWriter::BigEndianWriter(char* buf, size_t len) |
| : ptr_(buf), end_(ptr_ + len) { |
| // Ensure `len` does not cause `end_` to wrap around. |
| CHECK_GE(end_, ptr_); |
| } |
| |
| bool BigEndianWriter::Skip(size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| ptr_ += len; |
| return true; |
| } |
| |
| bool BigEndianWriter::WriteBytes(const void* buf, size_t len) { |
| if (len > remaining()) { |
| return false; |
| } |
| memcpy(ptr_, buf, len); |
| ptr_ += len; |
| return true; |
| } |
| |
| template <typename T> |
| bool BigEndianWriter::Write(T value) { |
| if (sizeof(T) > remaining()) { |
| return false; |
| } |
| WriteBigEndian<T>(ptr_, value); |
| ptr_ += sizeof(T); |
| return true; |
| } |
| |
| bool BigEndianWriter::WriteU8(uint8_t value) { |
| return Write(value); |
| } |
| |
| bool BigEndianWriter::WriteU16(uint16_t value) { |
| return Write(value); |
| } |
| |
| bool BigEndianWriter::WriteU32(uint32_t value) { |
| return Write(value); |
| } |
| |
| bool BigEndianWriter::WriteU64(uint64_t value) { |
| return Write(value); |
| } |
| |
| } // namespace base |