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-exception 6 // 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 16 using namespace llvm; 17 18 BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref) 19 : Stream(Ref) {} 20 21 BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream) 22 : Stream(Stream) {} 23 24 BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data, 25 llvm::support::endianness Endian) 26 : Stream(Data, Endian) {} 27 28 Error 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 35 Error 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 41 Error 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 47 Error 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 56 Error BinaryStreamWriter::writeFixedString(StringRef Str) { 57 58 return writeBytes(arrayRefFromStringRef(Str)); 59 } 60 61 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) { 62 return writeStreamRef(Ref, Ref.getLength()); 63 } 64 65 Error 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 it 68 // return us the entire stream as a contiguous buffer. There is no guarantee 69 // this can be satisfied by returning a reference straight from the buffer, as 70 // an implementation may not store all data in a single contiguous buffer. So 71 // 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 82 std::pair<BinaryStreamWriter, BinaryStreamWriter> 83 BinaryStreamWriter::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 std::make_pair(W1, W2); 93 } 94 95 Error 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