LLVM  7.0.0svn
MemoryBuffer.h
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1 //===--- MemoryBuffer.h - Memory Buffer Interface ---------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines the MemoryBuffer interface.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_MEMORYBUFFER_H
15 #define LLVM_SUPPORT_MEMORYBUFFER_H
16 
17 #include "llvm-c/Types.h"
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/ADT/Twine.h"
22 #include "llvm/Support/ErrorOr.h"
24 #include <cstddef>
25 #include <cstdint>
26 #include <memory>
27 
28 namespace llvm {
29 
30 class MemoryBufferRef;
31 
32 /// This interface provides simple read-only access to a block of memory, and
33 /// provides simple methods for reading files and standard input into a memory
34 /// buffer. In addition to basic access to the characters in the file, this
35 /// interface guarantees you can read one character past the end of the file,
36 /// and that this character will read as '\0'.
37 ///
38 /// The '\0' guarantee is needed to support an optimization -- it's intended to
39 /// be more efficient for clients which are reading all the data to stop
40 /// reading when they encounter a '\0' than to continually check the file
41 /// position to see if it has reached the end of the file.
42 class MemoryBuffer {
43  const char *BufferStart; // Start of the buffer.
44  const char *BufferEnd; // End of the buffer.
45 
46 
47 protected:
48  MemoryBuffer() = default;
49 
50  void init(const char *BufStart, const char *BufEnd,
51  bool RequiresNullTerminator);
52 
55 
56 public:
57  MemoryBuffer(const MemoryBuffer &) = delete;
58  MemoryBuffer &operator=(const MemoryBuffer &) = delete;
59  virtual ~MemoryBuffer();
60 
61  const char *getBufferStart() const { return BufferStart; }
62  const char *getBufferEnd() const { return BufferEnd; }
63  size_t getBufferSize() const { return BufferEnd-BufferStart; }
64 
65  StringRef getBuffer() const {
66  return StringRef(BufferStart, getBufferSize());
67  }
68 
69  /// Return an identifier for this buffer, typically the filename it was read
70  /// from.
71  virtual StringRef getBufferIdentifier() const { return "Unknown buffer"; }
72 
73  /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
74  /// if successful, otherwise returning null. If FileSize is specified, this
75  /// means that the client knows that the file exists and that it has the
76  /// specified size.
77  ///
78  /// \param IsVolatile Set to true to indicate that the contents of the file
79  /// can change outside the user's control, e.g. when libclang tries to parse
80  /// while the user is editing/updating the file or if the file is on an NFS.
82  getFile(const Twine &Filename, int64_t FileSize = -1,
83  bool RequiresNullTerminator = true, bool IsVolatile = false);
84 
85  /// Read all of the specified file into a MemoryBuffer as a stream
86  /// (i.e. until EOF reached). This is useful for special files that
87  /// look like a regular file but have 0 size (e.g. /proc/cpuinfo on Linux).
89  getFileAsStream(const Twine &Filename);
90 
91  /// Given an already-open file descriptor, map some slice of it into a
92  /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
93  /// Since this is in the middle of a file, the buffer is not null terminated.
95  getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize,
96  int64_t Offset, bool IsVolatile = false);
97 
98  /// Given an already-open file descriptor, read the file and return a
99  /// MemoryBuffer.
100  ///
101  /// \param IsVolatile Set to true to indicate that the contents of the file
102  /// can change outside the user's control, e.g. when libclang tries to parse
103  /// while the user is editing/updating the file or if the file is on an NFS.
105  getOpenFile(int FD, const Twine &Filename, uint64_t FileSize,
106  bool RequiresNullTerminator = true, bool IsVolatile = false);
107 
108  /// Open the specified memory range as a MemoryBuffer. Note that InputData
109  /// must be null terminated if RequiresNullTerminator is true.
110  static std::unique_ptr<MemoryBuffer>
111  getMemBuffer(StringRef InputData, StringRef BufferName = "",
112  bool RequiresNullTerminator = true);
113 
114  static std::unique_ptr<MemoryBuffer>
115  getMemBuffer(MemoryBufferRef Ref, bool RequiresNullTerminator = true);
116 
117  /// Open the specified memory range as a MemoryBuffer, copying the contents
118  /// and taking ownership of it. InputData does not have to be null terminated.
119  static std::unique_ptr<MemoryBuffer>
120  getMemBufferCopy(StringRef InputData, const Twine &BufferName = "");
121 
122  /// Read all of stdin into a file buffer, and return it.
124 
125  /// Open the specified file as a MemoryBuffer, or open stdin if the Filename
126  /// is "-".
128  getFileOrSTDIN(const Twine &Filename, int64_t FileSize = -1,
129  bool RequiresNullTerminator = true);
130 
131  /// Map a subrange of the specified file as a MemoryBuffer.
133  getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
134  bool IsVolatile = false);
135 
136  //===--------------------------------------------------------------------===//
137  // Provided for performance analysis.
138  //===--------------------------------------------------------------------===//
139 
140  /// The kind of memory backing used to support the MemoryBuffer.
141  enum BufferKind {
144  };
145 
146  /// Return information on the memory mechanism used to support the
147  /// MemoryBuffer.
148  virtual BufferKind getBufferKind() const = 0;
149 
151 
152 private:
153  virtual void anchor();
154 };
155 
156 /// This class is an extension of MemoryBuffer, which allows copy-on-write
157 /// access to the underlying contents. It only supports creation methods that
158 /// are guaranteed to produce a writable buffer. For example, mapping a file
159 /// read-only is not supported.
161 protected:
162  WritableMemoryBuffer() = default;
163 
166 
167 public:
171 
172  // const_cast is well-defined here, because the underlying buffer is
173  // guaranteed to have been initialized with a mutable buffer.
174  char *getBufferStart() {
175  return const_cast<char *>(MemoryBuffer::getBufferStart());
176  }
177  char *getBufferEnd() {
178  return const_cast<char *>(MemoryBuffer::getBufferEnd());
179  }
181  return {getBufferStart(), getBufferEnd()};
182  }
183 
185  getFile(const Twine &Filename, int64_t FileSize = -1,
186  bool IsVolatile = false);
187 
188  /// Map a subrange of the specified file as a WritableMemoryBuffer.
190  getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset,
191  bool IsVolatile = false);
192 
193  /// Allocate a new MemoryBuffer of the specified size that is not initialized.
194  /// Note that the caller should initialize the memory allocated by this
195  /// method. The memory is owned by the MemoryBuffer object.
196  static std::unique_ptr<WritableMemoryBuffer>
197  getNewUninitMemBuffer(size_t Size, const Twine &BufferName = "");
198 
199  /// Allocate a new zero-initialized MemoryBuffer of the specified size. Note
200  /// that the caller need not initialize the memory allocated by this method.
201  /// The memory is owned by the MemoryBuffer object.
202  static std::unique_ptr<WritableMemoryBuffer>
203  getNewMemBuffer(size_t Size, const Twine &BufferName = "");
204 
205 private:
206  // Hide these base class factory function so one can't write
207  // WritableMemoryBuffer::getXXX()
208  // and be surprised that he got a read-only Buffer.
216 };
217 
218 /// This class is an extension of MemoryBuffer, which allows write access to
219 /// the underlying contents and committing those changes to the original source.
220 /// It only supports creation methods that are guaranteed to produce a writable
221 /// buffer. For example, mapping a file read-only is not supported.
223 protected:
224  WriteThroughMemoryBuffer() = default;
225 
228 
229 public:
233 
234  // const_cast is well-defined here, because the underlying buffer is
235  // guaranteed to have been initialized with a mutable buffer.
236  char *getBufferStart() {
237  return const_cast<char *>(MemoryBuffer::getBufferStart());
238  }
239  char *getBufferEnd() {
240  return const_cast<char *>(MemoryBuffer::getBufferEnd());
241  }
243  return {getBufferStart(), getBufferEnd()};
244  }
245 
247  getFile(const Twine &Filename, int64_t FileSize = -1);
248 
249  /// Map a subrange of the specified file as a ReadWriteMemoryBuffer.
251  getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset);
252 
253 private:
254  // Hide these base class factory function so one can't write
255  // WritableMemoryBuffer::getXXX()
256  // and be surprised that he got a read-only Buffer.
264 };
265 
267  StringRef Buffer;
269 
270 public:
271  MemoryBufferRef() = default;
273  : Buffer(Buffer.getBuffer()), Identifier(Buffer.getBufferIdentifier()) {}
274  MemoryBufferRef(StringRef Buffer, StringRef Identifier)
275  : Buffer(Buffer), Identifier(Identifier) {}
276 
277  StringRef getBuffer() const { return Buffer; }
278 
280 
281  const char *getBufferStart() const { return Buffer.begin(); }
282  const char *getBufferEnd() const { return Buffer.end(); }
283  size_t getBufferSize() const { return Buffer.size(); }
284 };
285 
286 // Create wrappers for C Binding types (see CBindingWrapping.h).
288 
289 } // end namespace llvm
290 
291 #endif // LLVM_SUPPORT_MEMORYBUFFER_H
virtual StringRef getBufferIdentifier() const
Return an identifier for this buffer, typically the filename it was read from.
Definition: MemoryBuffer.h:71
void init(const char *BufStart, const char *BufEnd, bool RequiresNullTerminator)
init - Initialize this MemoryBuffer as a reference to externally allocated memory, memory that we know is already null terminated.
static ErrorOr< std::unique_ptr< MemoryBuffer > > getOpenFileSlice(int FD, const Twine &Filename, uint64_t MapSize, int64_t Offset, bool IsVolatile=false)
Given an already-open file descriptor, map some slice of it into a MemoryBuffer.
Represents either an error or a value T.
Definition: ErrorOr.h:69
StringRef getBuffer() const
Definition: MemoryBuffer.h:65
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
const char * getBufferEnd() const
Definition: MemoryBuffer.h:282
struct LLVMOpaqueMemoryBuffer * LLVMMemoryBufferRef
LLVM uses a polymorphic type hierarchy which C cannot represent, therefore parameters must be passed ...
Definition: Types.h:49
constexpr char IsVolatile[]
Key for Kernel::Arg::Metadata::mIsVolatile.
MemoryBuffer & operator=(const MemoryBuffer &)=delete
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE size_t size() const
size - Get the string size.
Definition: StringRef.h:138
static std::unique_ptr< MemoryBuffer > getMemBuffer(StringRef InputData, StringRef BufferName="", bool RequiresNullTerminator=true)
Open the specified memory range as a MemoryBuffer.
size_t getBufferSize() const
Definition: MemoryBuffer.h:63
virtual BufferKind getBufferKind() const =0
Return information on the memory mechanism used to support the MemoryBuffer.
#define DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ty, ref)
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
StringRef getBuffer() const
Definition: MemoryBuffer.h:277
The access may reference the value stored in memory.
May access map via data and modify it. Written to path.
Definition: FileSystem.h:1038
May only access map via const_data as read only.
Definition: FileSystem.h:1037
MutableArrayRef< char > getBuffer()
Definition: MemoryBuffer.h:242
static constexpr sys::fs::mapped_file_region::mapmode Mapmode
Definition: MemoryBuffer.h:53
static ErrorOr< std::unique_ptr< MemoryBuffer > > getSTDIN()
Read all of stdin into a file buffer, and return it.
MutableArrayRef - Represent a mutable reference to an array (0 or more elements consecutively in memo...
Definition: ArrayRef.h:291
size_t getBufferSize() const
Definition: MemoryBuffer.h:283
This class is an extension of MemoryBuffer, which allows write access to the underlying contents and ...
Definition: MemoryBuffer.h:222
MemoryBuffer()=default
MemoryBufferRef getMemBufferRef() const
This interface provides simple read-only access to a block of memory, and provides simple methods for...
Definition: MemoryBuffer.h:42
static std::unique_ptr< MemoryBuffer > getMemBufferCopy(StringRef InputData, const Twine &BufferName="")
Open the specified memory range as a MemoryBuffer, copying the contents and taking ownership of it...
StringRef getBufferIdentifier() const
Definition: MemoryBuffer.h:279
iterator begin() const
Definition: StringRef.h:106
May modify via data, but changes are lost on destruction.
Definition: FileSystem.h:1039
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFileSlice(const Twine &Filename, uint64_t MapSize, uint64_t Offset, bool IsVolatile=false)
Map a subrange of the specified file as a MemoryBuffer.
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFileOrSTDIN(const Twine &Filename, int64_t FileSize=-1, bool RequiresNullTerminator=true)
Open the specified file as a MemoryBuffer, or open stdin if the Filename is "-".
const char * getBufferEnd() const
Definition: MemoryBuffer.h:62
virtual ~MemoryBuffer()
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFileAsStream(const Twine &Filename)
Read all of the specified file into a MemoryBuffer as a stream (i.e.
This class is an extension of MemoryBuffer, which allows copy-on-write access to the underlying conte...
Definition: MemoryBuffer.h:160
BufferKind
The kind of memory backing used to support the MemoryBuffer.
Definition: MemoryBuffer.h:141
const char * getBufferStart() const
Definition: MemoryBuffer.h:61
MemoryBufferRef(MemoryBuffer &Buffer)
Definition: MemoryBuffer.h:272
Provides ErrorOr<T> smart pointer.
static ErrorOr< std::unique_ptr< MemoryBuffer > > getFile(const Twine &Filename, int64_t FileSize=-1, bool RequiresNullTerminator=true, bool IsVolatile=false)
Open the specified file as a MemoryBuffer, returning a new MemoryBuffer if successful, otherwise returning null.
const char * getBufferStart() const
Definition: MemoryBuffer.h:281
MemoryBufferRef(StringRef Buffer, StringRef Identifier)
Definition: MemoryBuffer.h:274
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
static ErrorOr< std::unique_ptr< MemoryBuffer > > getOpenFile(int FD, const Twine &Filename, uint64_t FileSize, bool RequiresNullTerminator=true, bool IsVolatile=false)
Given an already-open file descriptor, read the file and return a MemoryBuffer.
iterator end() const
Definition: StringRef.h:108
MutableArrayRef< char > getBuffer()
Definition: MemoryBuffer.h:180