1 //===- BinaryStreamReader.h - Reads objects from a binary stream *- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_SUPPORT_BINARYSTREAMREADER_H
11 #define LLVM_SUPPORT_BINARYSTREAMREADER_H
13 #include "llvm/ADT/ArrayRef.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/Support/BinaryStreamArray.h"
16 #include "llvm/Support/BinaryStreamRef.h"
17 #include "llvm/Support/ConvertUTF.h"
18 #include "llvm/Support/Endian.h"
19 #include "llvm/Support/Error.h"
20 #include "llvm/Support/type_traits.h"
23 #include <type_traits>
27 /// \brief Provides read only access to a subclass of `BinaryStream`. Provides
28 /// bounds checking and helpers for writing certain common data types such as
29 /// null-terminated strings, integers in various flavors of endianness, etc.
30 /// Can be subclassed to provide reading of custom datatypes, although no
32 class BinaryStreamReader {
34 BinaryStreamReader() = default;
35 explicit BinaryStreamReader(BinaryStreamRef Ref);
36 explicit BinaryStreamReader(BinaryStream &Stream);
37 explicit BinaryStreamReader(ArrayRef<uint8_t> Data,
38 llvm::support::endianness Endian);
39 explicit BinaryStreamReader(StringRef Data, llvm::support::endianness Endian);
41 BinaryStreamReader(const BinaryStreamReader &Other)
42 : Stream(Other.Stream), Offset(Other.Offset) {}
44 BinaryStreamReader &operator=(const BinaryStreamReader &Other) {
45 Stream = Other.Stream;
46 Offset = Other.Offset;
50 virtual ~BinaryStreamReader() {}
52 /// Read as much as possible from the underlying string at the current offset
53 /// without invoking a copy, and set \p Buffer to the resulting data slice.
54 /// Updates the stream's offset to point after the newly read data.
56 /// \returns a success error code if the data was successfully read, otherwise
57 /// returns an appropriate error code.
58 Error readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer);
60 /// Read \p Size bytes from the underlying stream at the current offset and
61 /// and set \p Buffer to the resulting data slice. Whether a copy occurs
62 /// depends on the implementation of the underlying stream. Updates the
63 /// stream's offset to point after the newly read data.
65 /// \returns a success error code if the data was successfully read, otherwise
66 /// returns an appropriate error code.
67 Error readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size);
69 /// Read an integer of the specified endianness into \p Dest and update the
70 /// stream's offset. The data is always copied from the stream's underlying
71 /// buffer into \p Dest. Updates the stream's offset to point after the newly
74 /// \returns a success error code if the data was successfully read, otherwise
75 /// returns an appropriate error code.
76 template <typename T> Error readInteger(T &Dest) {
77 static_assert(std::is_integral<T>::value,
78 "Cannot call readInteger with non-integral value!");
80 ArrayRef<uint8_t> Bytes;
81 if (auto EC = readBytes(Bytes, sizeof(T)))
84 Dest = llvm::support::endian::read<T, llvm::support::unaligned>(
85 Bytes.data(), Stream.getEndian());
86 return Error::success();
89 /// Similar to readInteger.
90 template <typename T> Error readEnum(T &Dest) {
91 static_assert(std::is_enum<T>::value,
92 "Cannot call readEnum with non-enum value!");
93 typename std::underlying_type<T>::type N;
94 if (auto EC = readInteger(N))
96 Dest = static_cast<T>(N);
97 return Error::success();
100 /// Read a null terminated string from \p Dest. Whether a copy occurs depends
101 /// on the implementation of the underlying stream. Updates the stream's
102 /// offset to point after the newly read data.
104 /// \returns a success error code if the data was successfully read, otherwise
105 /// returns an appropriate error code.
106 Error readCString(StringRef &Dest);
108 /// Similar to readCString, however read a null-terminated UTF16 string
111 /// \returns a success error code if the data was successfully read, otherwise
112 /// returns an appropriate error code.
113 Error readWideString(ArrayRef<UTF16> &Dest);
115 /// Read a \p Length byte string into \p Dest. Whether a copy occurs depends
116 /// on the implementation of the underlying stream. Updates the stream's
117 /// offset to point after the newly read data.
119 /// \returns a success error code if the data was successfully read, otherwise
120 /// returns an appropriate error code.
121 Error readFixedString(StringRef &Dest, uint32_t Length);
123 /// Read the entire remainder of the underlying stream into \p Ref. This is
124 /// equivalent to calling getUnderlyingStream().slice(Offset). Updates the
125 /// stream's offset to point to the end of the stream. Never causes a copy.
127 /// \returns a success error code if the data was successfully read, otherwise
128 /// returns an appropriate error code.
129 Error readStreamRef(BinaryStreamRef &Ref);
131 /// Read \p Length bytes from the underlying stream into \p Ref. This is
132 /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
133 /// Updates the stream's offset to point after the newly read object. Never
136 /// \returns a success error code if the data was successfully read, otherwise
137 /// returns an appropriate error code.
138 Error readStreamRef(BinaryStreamRef &Ref, uint32_t Length);
140 /// Read \p Length bytes from the underlying stream into \p Stream. This is
141 /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
142 /// Updates the stream's offset to point after the newly read object. Never
145 /// \returns a success error code if the data was successfully read, otherwise
146 /// returns an appropriate error code.
147 Error readSubstream(BinarySubstreamRef &Stream, uint32_t Size);
149 /// Get a pointer to an object of type T from the underlying stream, as if by
150 /// memcpy, and store the result into \p Dest. It is up to the caller to
151 /// ensure that objects of type T can be safely treated in this manner.
152 /// Updates the stream's offset to point after the newly read object. Whether
153 /// a copy occurs depends upon the implementation of the underlying
156 /// \returns a success error code if the data was successfully read, otherwise
157 /// returns an appropriate error code.
158 template <typename T> Error readObject(const T *&Dest) {
159 ArrayRef<uint8_t> Buffer;
160 if (auto EC = readBytes(Buffer, sizeof(T)))
162 Dest = reinterpret_cast<const T *>(Buffer.data());
163 return Error::success();
166 /// Get a reference to a \p NumElements element array of objects of type T
167 /// from the underlying stream as if by memcpy, and store the resulting array
168 /// slice into \p array. It is up to the caller to ensure that objects of
169 /// type T can be safely treated in this manner. Updates the stream's offset
170 /// to point after the newly read object. Whether a copy occurs depends upon
171 /// the implementation of the underlying stream.
173 /// \returns a success error code if the data was successfully read, otherwise
174 /// returns an appropriate error code.
175 template <typename T>
176 Error readArray(ArrayRef<T> &Array, uint32_t NumElements) {
177 ArrayRef<uint8_t> Bytes;
178 if (NumElements == 0) {
179 Array = ArrayRef<T>();
180 return Error::success();
183 if (NumElements > UINT32_MAX / sizeof(T))
184 return make_error<BinaryStreamError>(
185 stream_error_code::invalid_array_size);
187 if (auto EC = readBytes(Bytes, NumElements * sizeof(T)))
190 assert(alignmentAdjustment(Bytes.data(), alignof(T)) == 0 &&
191 "Reading at invalid alignment!");
193 Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements);
194 return Error::success();
197 /// Read a VarStreamArray of size \p Size bytes and store the result into
198 /// \p Array. Updates the stream's offset to point after the newly read
199 /// array. Never causes a copy (although iterating the elements of the
200 /// VarStreamArray may, depending upon the implementation of the underlying
203 /// \returns a success error code if the data was successfully read, otherwise
204 /// returns an appropriate error code.
205 template <typename T, typename U>
206 Error readArray(VarStreamArray<T, U> &Array, uint32_t Size) {
208 if (auto EC = readStreamRef(S, Size))
210 Array.setUnderlyingStream(S);
211 return Error::success();
214 /// Read a FixedStreamArray of \p NumItems elements and store the result into
215 /// \p Array. Updates the stream's offset to point after the newly read
216 /// array. Never causes a copy (although iterating the elements of the
217 /// FixedStreamArray may, depending upon the implementation of the underlying
220 /// \returns a success error code if the data was successfully read, otherwise
221 /// returns an appropriate error code.
222 template <typename T>
223 Error readArray(FixedStreamArray<T> &Array, uint32_t NumItems) {
225 Array = FixedStreamArray<T>();
226 return Error::success();
229 if (NumItems > UINT32_MAX / sizeof(T))
230 return make_error<BinaryStreamError>(
231 stream_error_code::invalid_array_size);
233 BinaryStreamRef View;
234 if (auto EC = readStreamRef(View, NumItems * sizeof(T)))
237 Array = FixedStreamArray<T>(View);
238 return Error::success();
241 bool empty() const { return bytesRemaining() == 0; }
242 void setOffset(uint32_t Off) { Offset = Off; }
243 uint32_t getOffset() const { return Offset; }
244 uint32_t getLength() const { return Stream.getLength(); }
245 uint32_t bytesRemaining() const { return getLength() - getOffset(); }
247 /// Advance the stream's offset by \p Amount bytes.
249 /// \returns a success error code if at least \p Amount bytes remain in the
250 /// stream, otherwise returns an appropriate error code.
251 Error skip(uint32_t Amount);
253 /// Examine the next byte of the underlying stream without advancing the
254 /// stream's offset. If the stream is empty the behavior is undefined.
256 /// \returns the next byte in the stream.
257 uint8_t peek() const;
259 Error padToAlignment(uint32_t Align);
261 std::pair<BinaryStreamReader, BinaryStreamReader>
262 split(uint32_t Offset) const;
265 BinaryStreamRef Stream;
270 #endif // LLVM_SUPPORT_BINARYSTREAMREADER_H