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 uint32_t OriginalOffset = getOffset(); 46 uint32_t FoundOffset = 0; 47 while (true) { 48 uint32_t ThisOffset = getOffset(); 49 ArrayRef<uint8_t> Buffer; 50 if (auto EC = readLongestContiguousChunk(Buffer)) 51 return EC; 52 StringRef S(reinterpret_cast<const char *>(Buffer.begin()), Buffer.size()); 53 size_t Pos = S.find_first_of('\0'); 54 if (LLVM_LIKELY(Pos != StringRef::npos)) { 55 FoundOffset = Pos + ThisOffset; 56 break; 57 } 58 } 59 assert(FoundOffset >= OriginalOffset); 60 61 setOffset(OriginalOffset); 62 size_t Length = FoundOffset - OriginalOffset; 63 64 if (auto EC = readFixedString(Dest, Length)) 65 return EC; 66 67 // Now set the offset back to after the null terminator. 68 setOffset(FoundOffset + 1); 69 return Error::success(); 70 } 71 72 Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) { 73 ArrayRef<uint8_t> Bytes; 74 if (auto EC = readBytes(Bytes, Length)) 75 return EC; 76 Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size()); 77 return Error::success(); 78 } 79 80 Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) { 81 return readStreamRef(Ref, bytesRemaining()); 82 } 83 84 Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) { 85 if (bytesRemaining() < Length) 86 return make_error<BinaryStreamError>(stream_error_code::stream_too_short); 87 Ref = Stream.slice(Offset, Length); 88 Offset += Length; 89 return Error::success(); 90 } 91 92 Error BinaryStreamReader::skip(uint32_t Amount) { 93 if (Amount > bytesRemaining()) 94 return make_error<BinaryStreamError>(stream_error_code::stream_too_short); 95 Offset += Amount; 96 return Error::success(); 97 } 98 99 Error BinaryStreamReader::padToAlignment(uint32_t Align) { 100 uint32_t NewOffset = alignTo(Offset, Align); 101 return skip(NewOffset - Offset); 102 } 103 104 uint8_t BinaryStreamReader::peek() const { 105 ArrayRef<uint8_t> Buffer; 106 auto EC = Stream.readBytes(Offset, 1, Buffer); 107 assert(!EC && "Cannot peek an empty buffer!"); 108 llvm::consumeError(std::move(EC)); 109 return Buffer[0]; 110 } 111 112 std::pair<BinaryStreamReader, BinaryStreamReader> 113 BinaryStreamReader::split(uint32_t Off) const { 114 assert(getLength() >= Off); 115 116 BinaryStreamRef First = Stream.drop_front(Offset); 117 118 BinaryStreamRef Second = First.drop_front(Off); 119 First = First.keep_front(Off); 120 BinaryStreamReader W1{First}; 121 BinaryStreamReader W2{Second}; 122 return std::make_pair(W1, W2); 123 }