LLVM  9.0.0svn
BinaryStreamReader.cpp
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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 
10 
13 #include "llvm/Support/LEB128.h"
14 
15 using namespace llvm;
17 
19 
21 
23  endianness Endian)
24  : Stream(Data, Endian) {}
25 
27  : Stream(Data, Endian) {}
28 
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 
38  if (auto EC = Stream.readBytes(Offset, Size, Buffer))
39  return EC;
40  Offset += Size;
41  return Error::success();
42 }
43 
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 
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 
75  uint32_t OriginalOffset = getOffset();
76  uint32_t FoundOffset = 0;
77  while (true) {
78  uint32_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 
103  uint32_t Length = 0;
104  uint32_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  uint32_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 
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 
131  return readStreamRef(Ref, bytesRemaining());
132 }
133 
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 
143  uint32_t Size) {
144  Stream.Offset = getOffset();
145  return readStreamRef(Stream.StreamData, Size);
146 }
147 
149  if (Amount > bytesRemaining())
150  return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
151  Offset += Amount;
152  return Error::success();
153 }
154 
156  uint32_t NewOffset = alignTo(Offset, Align);
157  return skip(NewOffset - Offset);
158 }
159 
160 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>
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 }
uint64_t CallInst * C
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
Error padToAlignment(uint32_t Align)
RefType slice(uint32_t Offset, uint32_t Len) const
Return a new BinaryStreamRef with the first Offset elements removed, and retaining exactly Len elemen...
Error readSubstream(BinarySubstreamRef &Stream, uint32_t Size)
Read Length bytes from the underlying stream into Stream.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
#define LLVM_LIKELY(EXPR)
Definition: Compiler.h:190
iterator begin() const
Definition: ArrayRef.h:136
Error readWideString(ArrayRef< UTF16 > &Dest)
Similar to readCString, however read a null-terminated UTF16 string instead.
Error readObject(const T *&Dest)
Get a pointer to an object of type T from the underlying stream, as if by memcpy, and store the resul...
uint8_t peek() const
Examine the next byte of the underlying stream without advancing the stream&#39;s offset.
uint64_t alignTo(uint64_t Value, uint64_t Align, uint64_t Skew=0)
Returns the next integer (mod 2**64) that is greater than or equal to Value and is a multiple of Alig...
Definition: MathExtras.h:684
unsigned short UTF16
Definition: ConvertUTF.h:110
Error readSLEB128(int64_t &Dest)
Read a signed LEB128 encoded value.
Error readULEB128(uint64_t &Dest)
Read an unsigned LEB128 encoded value.
int64_t decodeSLEB128(const uint8_t *p, unsigned *n=nullptr, const uint8_t *end=nullptr, const char **error=nullptr)
Utility function to decode a SLEB128 value.
Definition: LEB128.h:161
The access may reference the value stored in memory.
Error readCString(StringRef &Dest)
Read a null terminated string from Dest.
std::pair< BinaryStreamReader, BinaryStreamReader > split(uint32_t Offset) const
Error readFixedString(StringRef &Dest, uint32_t Length)
Read a Length byte string into Dest.
Error readBytes(uint32_t Offset, uint32_t Size, ArrayRef< uint8_t > &Buffer) const
Given an Offset into this StreamRef and a Size, return a reference to a buffer owned by the stream...
An interface for accessing data in a stream-like format, but which discourages copying.
Definition: BinaryStream.h:35
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:148
RefType drop_front(uint32_t N) const
Return a new BinaryStreamRef with the first N elements removed.
uint64_t decodeULEB128(const uint8_t *p, unsigned *n=nullptr, const uint8_t *end=nullptr, const char **error=nullptr)
Utility function to decode a ULEB128 value.
Definition: LEB128.h:128
void consumeError(Error Err)
Consume a Error without doing anything.
Definition: Error.h:981
BinaryStreamRef StreamData
void setOffset(uint32_t Off)
static ErrorSuccess success()
Create a success value.
Definition: Error.h:326
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
BinaryStreamRef is to BinaryStream what ArrayRef is to an Array.
static const size_t npos
Definition: StringRef.h:50
Error readBytes(ArrayRef< uint8_t > &Buffer, uint32_t Size)
Read Size bytes from the underlying stream at the current offset and and set Buffer to the resulting ...
LLVM_NODISCARD size_t find_first_of(char C, size_t From=0) const
Find the first character in the string that is C, or npos if not found.
Definition: StringRef.h:380
uint32_t Size
Definition: Profile.cpp:46
Error readStreamRef(BinaryStreamRef &Ref)
Read the entire remainder of the underlying stream into Ref.
Error skip(uint32_t Amount)
Advance the stream&#39;s offset by Amount bytes.
Error readLongestContiguousChunk(uint32_t Offset, ArrayRef< uint8_t > &Buffer) const
Given an Offset into this BinaryStreamRef, return a reference to the largest buffer the stream could ...
uint32_t bytesRemaining() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
RefType keep_front(uint32_t N) const
Return a new BinaryStreamRef with only the first N elements remaining.
Lightweight error class with error context and mandatory checking.
Definition: Error.h:157
Provides read only access to a subclass of BinaryStream.
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
Error readLongestContiguousChunk(ArrayRef< uint8_t > &Buffer)
Read as much as possible from the underlying string at the current offset without invoking a copy...
Error readArray(ArrayRef< T > &Array, uint32_t NumElements)
Get a reference to a NumElements element array of objects of type T from the underlying stream as if ...