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BinaryStreamReader.h
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1 //===- BinaryStreamReader.h - Reads objects from a binary stream *- C++ -*-===//
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 #ifndef LLVM_SUPPORT_BINARYSTREAMREADER_H
10 #define LLVM_SUPPORT_BINARYSTREAMREADER_H
11 
12 #include "llvm/ADT/ArrayRef.h"
13 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/Support/Endian.h"
18 #include "llvm/Support/Error.h"
20 
21 #include <string>
22 #include <type_traits>
23 
24 namespace llvm {
25 
26 /// Provides read only access to a subclass of `BinaryStream`. Provides
27 /// bounds checking and helpers for writing certain common data types such as
28 /// null-terminated strings, integers in various flavors of endianness, etc.
29 /// Can be subclassed to provide reading of custom datatypes, although no
30 /// are overridable.
32 public:
33  BinaryStreamReader() = default;
35  explicit BinaryStreamReader(BinaryStream &Stream);
39 
41  : Stream(Other.Stream), Offset(Other.Offset) {}
42 
44  Stream = Other.Stream;
45  Offset = Other.Offset;
46  return *this;
47  }
48 
49  virtual ~BinaryStreamReader() {}
50 
51  /// Read as much as possible from the underlying string at the current offset
52  /// without invoking a copy, and set \p Buffer to the resulting data slice.
53  /// Updates the stream's offset to point after the newly read data.
54  ///
55  /// \returns a success error code if the data was successfully read, otherwise
56  /// returns an appropriate error code.
58 
59  /// Read \p Size bytes from the underlying stream at the current offset and
60  /// and set \p Buffer to the resulting data slice. Whether a copy occurs
61  /// depends on the implementation of the underlying stream. Updates the
62  /// stream's offset to point after the newly read data.
63  ///
64  /// \returns a success error code if the data was successfully read, otherwise
65  /// returns an appropriate error code.
67 
68  /// Read an integer of the specified endianness into \p Dest and update the
69  /// stream's offset. The data is always copied from the stream's underlying
70  /// buffer into \p Dest. Updates the stream's offset to point after the newly
71  /// read data.
72  ///
73  /// \returns a success error code if the data was successfully read, otherwise
74  /// returns an appropriate error code.
75  template <typename T> Error readInteger(T &Dest) {
76  static_assert(std::is_integral<T>::value,
77  "Cannot call readInteger with non-integral value!");
78 
79  ArrayRef<uint8_t> Bytes;
80  if (auto EC = readBytes(Bytes, sizeof(T)))
81  return EC;
82 
83  Dest = llvm::support::endian::read<T, llvm::support::unaligned>(
84  Bytes.data(), Stream.getEndian());
85  return Error::success();
86  }
87 
88  /// Similar to readInteger.
89  template <typename T> Error readEnum(T &Dest) {
90  static_assert(std::is_enum<T>::value,
91  "Cannot call readEnum with non-enum value!");
92  typename std::underlying_type<T>::type N;
93  if (auto EC = readInteger(N))
94  return EC;
95  Dest = static_cast<T>(N);
96  return Error::success();
97  }
98 
99  /// Read an unsigned LEB128 encoded value.
100  ///
101  /// \returns a success error code if the data was successfully read, otherwise
102  /// returns an appropriate error code.
103  Error readULEB128(uint64_t &Dest);
104 
105  /// Read a signed LEB128 encoded value.
106  ///
107  /// \returns a success error code if the data was successfully read, otherwise
108  /// returns an appropriate error code.
109  Error readSLEB128(int64_t &Dest);
110 
111  /// Read a null terminated string from \p Dest. Whether a copy occurs depends
112  /// on the implementation of the underlying stream. Updates the stream's
113  /// offset to point after the newly read data.
114  ///
115  /// \returns a success error code if the data was successfully read, otherwise
116  /// returns an appropriate error code.
117  Error readCString(StringRef &Dest);
118 
119  /// Similar to readCString, however read a null-terminated UTF16 string
120  /// instead.
121  ///
122  /// \returns a success error code if the data was successfully read, otherwise
123  /// returns an appropriate error code.
125 
126  /// Read a \p Length byte string into \p Dest. Whether a copy occurs depends
127  /// on the implementation of the underlying stream. Updates the stream's
128  /// offset to point after the newly read data.
129  ///
130  /// \returns a success error code if the data was successfully read, otherwise
131  /// returns an appropriate error code.
132  Error readFixedString(StringRef &Dest, uint32_t Length);
133 
134  /// Read the entire remainder of the underlying stream into \p Ref. This is
135  /// equivalent to calling getUnderlyingStream().slice(Offset). Updates the
136  /// stream's offset to point to the end of the stream. Never causes a copy.
137  ///
138  /// \returns a success error code if the data was successfully read, otherwise
139  /// returns an appropriate error code.
141 
142  /// Read \p Length bytes from the underlying stream into \p Ref. This is
143  /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
144  /// Updates the stream's offset to point after the newly read object. Never
145  /// causes a copy.
146  ///
147  /// \returns a success error code if the data was successfully read, otherwise
148  /// returns an appropriate error code.
150 
151  /// Read \p Length bytes from the underlying stream into \p Stream. This is
152  /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
153  /// Updates the stream's offset to point after the newly read object. Never
154  /// causes a copy.
155  ///
156  /// \returns a success error code if the data was successfully read, otherwise
157  /// returns an appropriate error code.
159 
160  /// Get a pointer to an object of type T from the underlying stream, as if by
161  /// memcpy, and store the result into \p Dest. It is up to the caller to
162  /// ensure that objects of type T can be safely treated in this manner.
163  /// Updates the stream's offset to point after the newly read object. Whether
164  /// a copy occurs depends upon the implementation of the underlying
165  /// stream.
166  ///
167  /// \returns a success error code if the data was successfully read, otherwise
168  /// returns an appropriate error code.
169  template <typename T> Error readObject(const T *&Dest) {
170  ArrayRef<uint8_t> Buffer;
171  if (auto EC = readBytes(Buffer, sizeof(T)))
172  return EC;
173  Dest = reinterpret_cast<const T *>(Buffer.data());
174  return Error::success();
175  }
176 
177  /// Get a reference to a \p NumElements element array of objects of type T
178  /// from the underlying stream as if by memcpy, and store the resulting array
179  /// slice into \p array. It is up to the caller to ensure that objects of
180  /// type T can be safely treated in this manner. Updates the stream's offset
181  /// to point after the newly read object. Whether a copy occurs depends upon
182  /// the implementation of the underlying stream.
183  ///
184  /// \returns a success error code if the data was successfully read, otherwise
185  /// returns an appropriate error code.
186  template <typename T>
187  Error readArray(ArrayRef<T> &Array, uint32_t NumElements) {
188  ArrayRef<uint8_t> Bytes;
189  if (NumElements == 0) {
190  Array = ArrayRef<T>();
191  return Error::success();
192  }
193 
194  if (NumElements > UINT32_MAX / sizeof(T))
195  return make_error<BinaryStreamError>(
197 
198  if (auto EC = readBytes(Bytes, NumElements * sizeof(T)))
199  return EC;
200 
201  assert(alignmentAdjustment(Bytes.data(), alignof(T)) == 0 &&
202  "Reading at invalid alignment!");
203 
204  Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements);
205  return Error::success();
206  }
207 
208  /// Read a VarStreamArray of size \p Size bytes and store the result into
209  /// \p Array. Updates the stream's offset to point after the newly read
210  /// array. Never causes a copy (although iterating the elements of the
211  /// VarStreamArray may, depending upon the implementation of the underlying
212  /// stream).
213  ///
214  /// \returns a success error code if the data was successfully read, otherwise
215  /// returns an appropriate error code.
216  template <typename T, typename U>
218  uint32_t Skew = 0) {
219  BinaryStreamRef S;
220  if (auto EC = readStreamRef(S, Size))
221  return EC;
222  Array.setUnderlyingStream(S, Skew);
223  return Error::success();
224  }
225 
226  /// Read a FixedStreamArray of \p NumItems elements and store the result into
227  /// \p Array. Updates the stream's offset to point after the newly read
228  /// array. Never causes a copy (although iterating the elements of the
229  /// FixedStreamArray may, depending upon the implementation of the underlying
230  /// stream).
231  ///
232  /// \returns a success error code if the data was successfully read, otherwise
233  /// returns an appropriate error code.
234  template <typename T>
236  if (NumItems == 0) {
237  Array = FixedStreamArray<T>();
238  return Error::success();
239  }
240 
241  if (NumItems > UINT32_MAX / sizeof(T))
242  return make_error<BinaryStreamError>(
244 
245  BinaryStreamRef View;
246  if (auto EC = readStreamRef(View, NumItems * sizeof(T)))
247  return EC;
248 
249  Array = FixedStreamArray<T>(View);
250  return Error::success();
251  }
252 
253  bool empty() const { return bytesRemaining() == 0; }
254  void setOffset(uint32_t Off) { Offset = Off; }
255  uint32_t getOffset() const { return Offset; }
256  uint32_t getLength() const { return Stream.getLength(); }
257  uint32_t bytesRemaining() const { return getLength() - getOffset(); }
258 
259  /// Advance the stream's offset by \p Amount bytes.
260  ///
261  /// \returns a success error code if at least \p Amount bytes remain in the
262  /// stream, otherwise returns an appropriate error code.
263  Error skip(uint32_t Amount);
264 
265  /// Examine the next byte of the underlying stream without advancing the
266  /// stream's offset. If the stream is empty the behavior is undefined.
267  ///
268  /// \returns the next byte in the stream.
269  uint8_t peek() const;
270 
272 
273  std::pair<BinaryStreamReader, BinaryStreamReader>
274  split(uint32_t Offset) const;
275 
276 private:
277  BinaryStreamRef Stream;
278  uint32_t Offset = 0;
279 };
280 } // namespace llvm
281 
282 #endif // LLVM_SUPPORT_BINARYSTREAMREADER_H
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
Error padToAlignment(uint32_t Align)
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
Error readInteger(T &Dest)
Read an integer of the specified endianness into Dest and update the stream&#39;s offset.
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.
FixedStreamArray is similar to VarStreamArray, except with each record having a fixed-length.
BinaryStreamReader & operator=(const BinaryStreamReader &Other)
Error readSLEB128(int64_t &Dest)
Read a signed LEB128 encoded value.
Error readULEB128(uint64_t &Dest)
Read an unsigned LEB128 encoded value.
void setUnderlyingStream(BinaryStreamRef S, uint32_t Skew=0)
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.
virtual llvm::support::endianness getEndian() const =0
Error readArray(FixedStreamArray< T > &Array, uint32_t NumItems)
Read a FixedStreamArray of NumItems elements and store the result into Array.
An interface for accessing data in a stream-like format, but which discourages copying.
Definition: BinaryStream.h:35
size_t alignmentAdjustment(const void *Ptr, size_t Alignment)
Returns the necessary adjustment for aligning Ptr to Alignment bytes, rounding up.
Definition: MathExtras.h:633
Error readArray(VarStreamArray< T, U > &Array, uint32_t Size, uint32_t Skew=0)
Read a VarStreamArray of size Size bytes and store the result into Array.
BinaryStreamReader(const BinaryStreamReader &Other)
const T * data() const
Definition: ArrayRef.h:145
void setOffset(uint32_t Off)
static ErrorSuccess success()
Create a success value.
Definition: Error.h:326
BinaryStreamRef is to BinaryStream what ArrayRef is to an Array.
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 ...
#define N
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.
uint32_t bytesRemaining() const
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
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 readEnum(T &Dest)
Similar to readInteger.
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 ...