105 lines · cpp
1//===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "llvm/Support/BinaryStreamWriter.h"10 11#include "llvm/ADT/StringExtras.h"12#include "llvm/Support/BinaryStreamReader.h"13#include "llvm/Support/BinaryStreamRef.h"14#include "llvm/Support/LEB128.h"15 16using namespace llvm;17 18BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref)19 : Stream(Ref) {}20 21BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)22 : Stream(Stream) {}23 24BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,25 llvm::endianness Endian)26 : Stream(Data, Endian) {}27 28Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {29 if (auto EC = Stream.writeBytes(Offset, Buffer))30 return EC;31 Offset += Buffer.size();32 return Error::success();33}34 35Error BinaryStreamWriter::writeULEB128(uint64_t Value) {36 uint8_t EncodedBytes[10] = {0};37 unsigned Size = encodeULEB128(Value, &EncodedBytes[0]);38 return writeBytes({EncodedBytes, Size});39}40 41Error BinaryStreamWriter::writeSLEB128(int64_t Value) {42 uint8_t EncodedBytes[10] = {0};43 unsigned Size = encodeSLEB128(Value, &EncodedBytes[0]);44 return writeBytes({EncodedBytes, Size});45}46 47Error BinaryStreamWriter::writeCString(StringRef Str) {48 if (auto EC = writeFixedString(Str))49 return EC;50 if (auto EC = writeObject('\0'))51 return EC;52 53 return Error::success();54}55 56Error BinaryStreamWriter::writeFixedString(StringRef Str) {57 58 return writeBytes(arrayRefFromStringRef(Str));59}60 61Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {62 return writeStreamRef(Ref, Ref.getLength());63}64 65Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint64_t Length) {66 BinaryStreamReader SrcReader(Ref.slice(0, Length));67 // This is a bit tricky. If we just call readBytes, we are requiring that it68 // return us the entire stream as a contiguous buffer. There is no guarantee69 // this can be satisfied by returning a reference straight from the buffer, as70 // an implementation may not store all data in a single contiguous buffer. So71 // we iterate over each contiguous chunk, writing each one in succession.72 while (SrcReader.bytesRemaining() > 0) {73 ArrayRef<uint8_t> Chunk;74 if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))75 return EC;76 if (auto EC = writeBytes(Chunk))77 return EC;78 }79 return Error::success();80}81 82std::pair<BinaryStreamWriter, BinaryStreamWriter>83BinaryStreamWriter::split(uint64_t Off) const {84 assert(getLength() >= Off);85 86 WritableBinaryStreamRef First = Stream.drop_front(Offset);87 88 WritableBinaryStreamRef Second = First.drop_front(Off);89 First = First.keep_front(Off);90 BinaryStreamWriter W1{First};91 BinaryStreamWriter W2{Second};92 return {W1, W2};93}94 95Error BinaryStreamWriter::padToAlignment(uint32_t Align) {96 uint64_t NewOffset = alignTo(Offset, Align);97 const uint64_t ZerosSize = 64;98 static constexpr char Zeros[ZerosSize] = {};99 while (Offset < NewOffset)100 if (auto E = writeArray(101 ArrayRef<char>(Zeros, std::min(ZerosSize, NewOffset - Offset))))102 return E;103 return Error::success();104}105