1 //===- BinaryStreamReader.cpp - Reads objects from a binary stream --------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #include "llvm/Support/BinaryStreamReader.h" 11 12 #include "llvm/Support/BinaryStreamError.h" 13 #include "llvm/Support/BinaryStreamRef.h" 14 15 using namespace llvm; 16 using endianness = llvm::support::endianness; 17 18 BinaryStreamReader::BinaryStreamReader(BinaryStreamRef Ref) : Stream(Ref) {} 19 20 BinaryStreamReader::BinaryStreamReader(BinaryStream &Stream) : Stream(Stream) {} 21 22 BinaryStreamReader::BinaryStreamReader(ArrayRef<uint8_t> Data, 23 endianness Endian) 24 : Stream(Data, Endian) {} 25 26 BinaryStreamReader::BinaryStreamReader(StringRef Data, endianness Endian) 27 : Stream(Data, Endian) {} 28 29 Error BinaryStreamReader::readLongestContiguousChunk( 30 ArrayRef<uint8_t> &Buffer) { 31 if (auto EC = Stream.readLongestContiguousChunk(Offset, Buffer)) 32 return EC; 33 Offset += Buffer.size(); 34 return Error::success(); 35 } 36 37 Error BinaryStreamReader::readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size) { 38 if (auto EC = Stream.readBytes(Offset, Size, Buffer)) 39 return EC; 40 Offset += Size; 41 return Error::success(); 42 } 43 44 Error BinaryStreamReader::readCString(StringRef &Dest) { 45 // TODO: This could be made more efficient by using readLongestContiguousChunk 46 // and searching for null terminators in the resulting buffer. 47 48 uint32_t Length = 0; 49 // First compute the length of the string by reading 1 byte at a time. 50 uint32_t OriginalOffset = getOffset(); 51 const char *C; 52 while (true) { 53 if (auto EC = readObject(C)) 54 return EC; 55 if (*C == '\0') 56 break; 57 ++Length; 58 } 59 // Now go back and request a reference for that many bytes. 60 uint32_t NewOffset = getOffset(); 61 setOffset(OriginalOffset); 62 63 if (auto EC = readFixedString(Dest, Length)) 64 return EC; 65 66 // Now set the offset back to where it was after we calculated the length. 67 setOffset(NewOffset); 68 return Error::success(); 69 } 70 71 Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) { 72 ArrayRef<uint8_t> Bytes; 73 if (auto EC = readBytes(Bytes, Length)) 74 return EC; 75 Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size()); 76 return Error::success(); 77 } 78 79 Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) { 80 return readStreamRef(Ref, bytesRemaining()); 81 } 82 83 Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) { 84 if (bytesRemaining() < Length) 85 return make_error<BinaryStreamError>(stream_error_code::stream_too_short); 86 Ref = Stream.slice(Offset, Length); 87 Offset += Length; 88 return Error::success(); 89 } 90 91 Error BinaryStreamReader::skip(uint32_t Amount) { 92 if (Amount > bytesRemaining()) 93 return make_error<BinaryStreamError>(stream_error_code::stream_too_short); 94 Offset += Amount; 95 return Error::success(); 96 } 97 98 Error BinaryStreamReader::padToAlignment(uint32_t Align) { 99 uint32_t NewOffset = alignTo(Offset, Align); 100 return skip(NewOffset - Offset); 101 } 102 103 uint8_t BinaryStreamReader::peek() const { 104 ArrayRef<uint8_t> Buffer; 105 auto EC = Stream.readBytes(Offset, 1, Buffer); 106 assert(!EC && "Cannot peek an empty buffer!"); 107 llvm::consumeError(std::move(EC)); 108 return Buffer[0]; 109 } 110 111 std::pair<BinaryStreamReader, BinaryStreamReader> 112 BinaryStreamReader::split(uint32_t Off) const { 113 assert(getLength() >= Off); 114 115 BinaryStreamRef First = Stream.drop_front(Offset); 116 117 BinaryStreamRef Second = First.drop_front(Off); 118 First = First.keep_front(Off); 119 BinaryStreamReader W1{First}; 120 BinaryStreamReader W2{Second}; 121 return std::make_pair(W1, W2); 122 }