1 //===- BinaryStreamReader.cpp - Reads objects from a binary stream --------===//
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/BinaryStreamReader.h"
10
11 #include "llvm/Support/BinaryStreamError.h"
12 #include "llvm/Support/BinaryStreamRef.h"
13 #include "llvm/Support/LEB128.h"
14
15 using namespace llvm;
16 using endianness = llvm::support::endianness;
17
BinaryStreamReader(BinaryStreamRef Ref)18 BinaryStreamReader::BinaryStreamReader(BinaryStreamRef Ref) : Stream(Ref) {}
19
BinaryStreamReader(BinaryStream & Stream)20 BinaryStreamReader::BinaryStreamReader(BinaryStream &Stream) : Stream(Stream) {}
21
BinaryStreamReader(ArrayRef<uint8_t> Data,endianness Endian)22 BinaryStreamReader::BinaryStreamReader(ArrayRef<uint8_t> Data,
23 endianness Endian)
24 : Stream(Data, Endian) {}
25
BinaryStreamReader(StringRef Data,endianness Endian)26 BinaryStreamReader::BinaryStreamReader(StringRef Data, endianness Endian)
27 : Stream(Data, Endian) {}
28
readLongestContiguousChunk(ArrayRef<uint8_t> & Buffer)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
readBytes(ArrayRef<uint8_t> & Buffer,uint32_t Size)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
readULEB128(uint64_t & Dest)44 Error BinaryStreamReader::readULEB128(uint64_t &Dest) {
45 SmallVector<uint8_t, 10> EncodedBytes;
46 ArrayRef<uint8_t> NextByte;
47
48 // Copy the encoded ULEB into the buffer.
49 do {
50 if (auto Err = readBytes(NextByte, 1))
51 return Err;
52 EncodedBytes.push_back(NextByte[0]);
53 } while (NextByte[0] & 0x80);
54
55 Dest = decodeULEB128(EncodedBytes.begin(), nullptr, EncodedBytes.end());
56 return Error::success();
57 }
58
readSLEB128(int64_t & Dest)59 Error BinaryStreamReader::readSLEB128(int64_t &Dest) {
60 SmallVector<uint8_t, 10> EncodedBytes;
61 ArrayRef<uint8_t> NextByte;
62
63 // Copy the encoded ULEB into the buffer.
64 do {
65 if (auto Err = readBytes(NextByte, 1))
66 return Err;
67 EncodedBytes.push_back(NextByte[0]);
68 } while (NextByte[0] & 0x80);
69
70 Dest = decodeSLEB128(EncodedBytes.begin(), nullptr, EncodedBytes.end());
71 return Error::success();
72 }
73
readCString(StringRef & Dest)74 Error BinaryStreamReader::readCString(StringRef &Dest) {
75 uint64_t OriginalOffset = getOffset();
76 uint64_t FoundOffset = 0;
77 while (true) {
78 uint64_t ThisOffset = getOffset();
79 ArrayRef<uint8_t> Buffer;
80 if (auto EC = readLongestContiguousChunk(Buffer))
81 return EC;
82 StringRef S(reinterpret_cast<const char *>(Buffer.begin()), Buffer.size());
83 size_t Pos = S.find_first_of('\0');
84 if (LLVM_LIKELY(Pos != StringRef::npos)) {
85 FoundOffset = Pos + ThisOffset;
86 break;
87 }
88 }
89 assert(FoundOffset >= OriginalOffset);
90
91 setOffset(OriginalOffset);
92 size_t Length = FoundOffset - OriginalOffset;
93
94 if (auto EC = readFixedString(Dest, Length))
95 return EC;
96
97 // Now set the offset back to after the null terminator.
98 setOffset(FoundOffset + 1);
99 return Error::success();
100 }
101
readWideString(ArrayRef<UTF16> & Dest)102 Error BinaryStreamReader::readWideString(ArrayRef<UTF16> &Dest) {
103 uint64_t Length = 0;
104 uint64_t OriginalOffset = getOffset();
105 const UTF16 *C;
106 while (true) {
107 if (auto EC = readObject(C))
108 return EC;
109 if (*C == 0x0000)
110 break;
111 ++Length;
112 }
113 uint64_t NewOffset = getOffset();
114 setOffset(OriginalOffset);
115
116 if (auto EC = readArray(Dest, Length))
117 return EC;
118 setOffset(NewOffset);
119 return Error::success();
120 }
121
readFixedString(StringRef & Dest,uint32_t Length)122 Error BinaryStreamReader::readFixedString(StringRef &Dest, uint32_t Length) {
123 ArrayRef<uint8_t> Bytes;
124 if (auto EC = readBytes(Bytes, Length))
125 return EC;
126 Dest = StringRef(reinterpret_cast<const char *>(Bytes.begin()), Bytes.size());
127 return Error::success();
128 }
129
readStreamRef(BinaryStreamRef & Ref)130 Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref) {
131 return readStreamRef(Ref, bytesRemaining());
132 }
133
readStreamRef(BinaryStreamRef & Ref,uint32_t Length)134 Error BinaryStreamReader::readStreamRef(BinaryStreamRef &Ref, uint32_t Length) {
135 if (bytesRemaining() < Length)
136 return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
137 Ref = Stream.slice(Offset, Length);
138 Offset += Length;
139 return Error::success();
140 }
141
readSubstream(BinarySubstreamRef & Ref,uint32_t Length)142 Error BinaryStreamReader::readSubstream(BinarySubstreamRef &Ref,
143 uint32_t Length) {
144 Ref.Offset = getOffset();
145 return readStreamRef(Ref.StreamData, Length);
146 }
147
skip(uint64_t Amount)148 Error BinaryStreamReader::skip(uint64_t Amount) {
149 if (Amount > bytesRemaining())
150 return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
151 Offset += Amount;
152 return Error::success();
153 }
154
padToAlignment(uint32_t Align)155 Error BinaryStreamReader::padToAlignment(uint32_t Align) {
156 uint32_t NewOffset = alignTo(Offset, Align);
157 return skip(NewOffset - Offset);
158 }
159
peek() const160 uint8_t BinaryStreamReader::peek() const {
161 ArrayRef<uint8_t> Buffer;
162 auto EC = Stream.readBytes(Offset, 1, Buffer);
163 assert(!EC && "Cannot peek an empty buffer!");
164 llvm::consumeError(std::move(EC));
165 return Buffer[0];
166 }
167
168 std::pair<BinaryStreamReader, BinaryStreamReader>
split(uint64_t Off) const169 BinaryStreamReader::split(uint64_t Off) const {
170 assert(getLength() >= Off);
171
172 BinaryStreamRef First = Stream.drop_front(Offset);
173
174 BinaryStreamRef Second = First.drop_front(Off);
175 First = First.keep_front(Off);
176 BinaryStreamReader W1{First};
177 BinaryStreamReader W2{Second};
178 return std::make_pair(W1, W2);
179 }
180