include/llvm/Support/BinaryStreamReader.h

   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"
  14 #include "llvm/Support/BinaryStreamArray.h"
  15 #include "llvm/Support/BinaryStreamRef.h"
  16 #include "llvm/Support/ConvertUTF.h"
  17 #include "llvm/Support/Endian.h"
  18 #include "llvm/Support/Error.h"
  19 #include "llvm/Support/type_traits.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.
  31 class BinaryStreamReader {
  32 public:
  33   BinaryStreamReader() = default;
  34   explicit BinaryStreamReader(BinaryStreamRef Ref);
  35   explicit BinaryStreamReader(BinaryStream &Stream);
  36   explicit BinaryStreamReader(ArrayRef<uint8_t> Data,
  37                               llvm::support::endianness Endian);
  38   explicit BinaryStreamReader(StringRef Data, llvm::support::endianness Endian);
  39
  40   BinaryStreamReader(const BinaryStreamReader &Other)
  41       : Stream(Other.Stream), Offset(Other.Offset) {}
  42
  43   BinaryStreamReader &operator=(const BinaryStreamReader &Other) {
  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.
  57   Error readLongestContiguousChunk(ArrayRef<uint8_t> &Buffer);
  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.
  66   Error readBytes(ArrayRef<uint8_t> &Buffer, uint32_t Size);
  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 a null terminated string from \p Dest.  Whether a copy occurs depends
 100   /// on the implementation of the underlying stream.  Updates the stream's
 101   /// offset to point after the newly read data.
 102   ///
 103   /// \returns a success error code if the data was successfully read, otherwise
 104   /// returns an appropriate error code.
 105   Error readCString(StringRef &Dest);
 106
 107   /// Similar to readCString, however read a null-terminated UTF16 string
 108   /// instead.
 109   ///
 110   /// \returns a success error code if the data was successfully read, otherwise
 111   /// returns an appropriate error code.
 112   Error readWideString(ArrayRef<UTF16> &Dest);
 113
 114   /// Read a \p Length byte string into \p Dest.  Whether a copy occurs depends
 115   /// on the implementation of the underlying stream.  Updates the stream's
 116   /// offset to point after the newly read data.
 117   ///
 118   /// \returns a success error code if the data was successfully read, otherwise
 119   /// returns an appropriate error code.
 120   Error readFixedString(StringRef &Dest, uint32_t Length);
 121
 122   /// Read the entire remainder of the underlying stream into \p Ref.  This is
 123   /// equivalent to calling getUnderlyingStream().slice(Offset).  Updates the
 124   /// stream's offset to point to the end of the stream.  Never causes a copy.
 125   ///
 126   /// \returns a success error code if the data was successfully read, otherwise
 127   /// returns an appropriate error code.
 128   Error readStreamRef(BinaryStreamRef &Ref);
 129
 130   /// Read \p Length bytes from the underlying stream into \p Ref.  This is
 131   /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
 132   /// Updates the stream's offset to point after the newly read object.  Never
 133   /// causes a copy.
 134   ///
 135   /// \returns a success error code if the data was successfully read, otherwise
 136   /// returns an appropriate error code.
 137   Error readStreamRef(BinaryStreamRef &Ref, uint32_t Length);
 138
 139   /// Read \p Length bytes from the underlying stream into \p Stream.  This is
 140   /// equivalent to calling getUnderlyingStream().slice(Offset, Length).
 141   /// Updates the stream's offset to point after the newly read object.  Never
 142   /// causes a copy.
 143   ///
 144   /// \returns a success error code if the data was successfully read, otherwise
 145   /// returns an appropriate error code.
 146   Error readSubstream(BinarySubstreamRef &Stream, uint32_t Size);
 147
 148   /// Get a pointer to an object of type T from the underlying stream, as if by
 149   /// memcpy, and store the result into \p Dest.  It is up to the caller to
 150   /// ensure that objects of type T can be safely treated in this manner.
 151   /// Updates the stream's offset to point after the newly read object.  Whether
 152   /// a copy occurs depends upon the implementation of the underlying
 153   /// stream.
 154   ///
 155   /// \returns a success error code if the data was successfully read, otherwise
 156   /// returns an appropriate error code.
 157   template <typename T> Error readObject(const T *&Dest) {
 158     ArrayRef<uint8_t> Buffer;
 159     if (auto EC = readBytes(Buffer, sizeof(T)))
 160       return EC;
 161     Dest = reinterpret_cast<const T *>(Buffer.data());
 162     return Error::success();
 163   }
 164
 165   /// Get a reference to a \p NumElements element array of objects of type T
 166   /// from the underlying stream as if by memcpy, and store the resulting array
 167   /// slice into \p array.  It is up to the caller to ensure that objects of
 168   /// type T can be safely treated in this manner.  Updates the stream's offset
 169   /// to point after the newly read object.  Whether a copy occurs depends upon
 170   /// the implementation of the underlying stream.
 171   ///
 172   /// \returns a success error code if the data was successfully read, otherwise
 173   /// returns an appropriate error code.
 174   template <typename T>
 175   Error readArray(ArrayRef<T> &Array, uint32_t NumElements) {
 176     ArrayRef<uint8_t> Bytes;
 177     if (NumElements == 0) {
 178       Array = ArrayRef<T>();
 179       return Error::success();
 180     }
 181
 182     if (NumElements > UINT32_MAX / sizeof(T))
 183       return make_error<BinaryStreamError>(
 184           stream_error_code::invalid_array_size);
 185
 186     if (auto EC = readBytes(Bytes, NumElements * sizeof(T)))
 187       return EC;
 188
 189     assert(alignmentAdjustment(Bytes.data(), alignof(T)) == 0 &&
 190            "Reading at invalid alignment!");
 191
 192     Array = ArrayRef<T>(reinterpret_cast<const T *>(Bytes.data()), NumElements);
 193     return Error::success();
 194   }
 195
 196   /// Read a VarStreamArray of size \p Size bytes and store the result into
 197   /// \p Array.  Updates the stream's offset to point after the newly read
 198   /// array.  Never causes a copy (although iterating the elements of the
 199   /// VarStreamArray may, depending upon the implementation of the underlying
 200   /// stream).
 201   ///
 202   /// \returns a success error code if the data was successfully read, otherwise
 203   /// returns an appropriate error code.
 204   template <typename T, typename U>
 205   Error readArray(VarStreamArray<T, U> &Array, uint32_t Size,
 206                   uint32_t Skew = 0) {
 207     BinaryStreamRef S;
 208     if (auto EC = readStreamRef(S, Size))
 209       return EC;
 210     Array.setUnderlyingStream(S, Skew);
 211     return Error::success();
 212   }
 213
 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
 218   /// stream).
 219   ///
 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) {
 224     if (NumItems == 0) {
 225       Array = FixedStreamArray<T>();
 226       return Error::success();
 227     }
 228
 229     if (NumItems > UINT32_MAX / sizeof(T))
 230       return make_error<BinaryStreamError>(
 231           stream_error_code::invalid_array_size);
 232
 233     BinaryStreamRef View;
 234     if (auto EC = readStreamRef(View, NumItems * sizeof(T)))
 235       return EC;
 236
 237     Array = FixedStreamArray<T>(View);
 238     return Error::success();
 239   }
 240
 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(); }
 246
 247   /// Advance the stream's offset by \p Amount bytes.
 248   ///
 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);
 252
 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.
 255   ///
 256   /// \returns the next byte in the stream.
 257   uint8_t peek() const;
 258
 259   Error padToAlignment(uint32_t Align);
 260
 261   std::pair<BinaryStreamReader, BinaryStreamReader>
 262   split(uint32_t Offset) const;
 263
 264 private:
 265   BinaryStreamRef Stream;
 266   uint32_t Offset = 0;
 267 };
 268 } // namespace llvm
 269
 270 #endif // LLVM_SUPPORT_BINARYSTREAMREADER_H