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/Support.h"
18#include "llvm/ADT/Twine.h"
19#include "llvm/Support/CBindingWrapping.h"
20#include "llvm/Support/Compiler.h"
21#include "llvm/Support/DataTypes.h"
22#include "llvm/Support/ErrorOr.h"
23#include <memory>
24#include <system_error>
25
26namespace llvm {
27/// MemoryBuffer - This interface provides simple read-only access to a block
28/// of memory, and provides simple methods for reading files and standard input
29/// into a memory buffer.  In addition to basic access to the characters in the
30/// file, this interface guarantees you can read one character past the end of
31/// the file, and that this character will read as '\0'.
32///
33/// The '\0' guarantee is needed to support an optimization -- it's intended to
34/// be more efficient for clients which are reading all the data to stop
35/// reading when they encounter a '\0' than to continually check the file
36/// position to see if it has reached the end of the file.
37class MemoryBuffer {
38  const char *BufferStart; // Start of the buffer.
39  const char *BufferEnd;   // End of the buffer.
40
41  MemoryBuffer(const MemoryBuffer &) LLVM_DELETED_FUNCTION;
42  MemoryBuffer &operator=(const MemoryBuffer &) LLVM_DELETED_FUNCTION;
43protected:
44  MemoryBuffer() {}
45  void init(const char *BufStart, const char *BufEnd,
46            bool RequiresNullTerminator);
47public:
48  virtual ~MemoryBuffer();
49
50  const char *getBufferStart() const { return BufferStart; }
51  const char *getBufferEnd() const   { return BufferEnd; }
52  size_t getBufferSize() const { return BufferEnd-BufferStart; }
53
54  StringRef getBuffer() const {
55    return StringRef(BufferStart, getBufferSize());
56  }
57
58  /// getBufferIdentifier - Return an identifier for this buffer, typically the
59  /// filename it was read from.
60  virtual const char *getBufferIdentifier() const {
61    return "Unknown buffer";
62  }
63
64  /// Open the specified file as a MemoryBuffer, returning a new MemoryBuffer
65  /// if successful, otherwise returning null. If FileSize is specified, this
66  /// means that the client knows that the file exists and that it has the
67  /// specified size.
68  ///
69  /// \param IsVolatileSize Set to true to indicate that the file size may be
70  /// changing, e.g. when libclang tries to parse while the user is
71  /// editing/updating the file.
72  static ErrorOr<std::unique_ptr<MemoryBuffer>>
73  getFile(Twine Filename, int64_t FileSize = -1,
74          bool RequiresNullTerminator = true, bool IsVolatileSize = false);
75
76  /// Given an already-open file descriptor, map some slice of it into a
77  /// MemoryBuffer. The slice is specified by an \p Offset and \p MapSize.
78  /// Since this is in the middle of a file, the buffer is not null terminated.
79  ///
80  /// \param IsVolatileSize Set to true to indicate that the file size may be
81  /// changing, e.g. when libclang tries to parse while the user is
82  /// editing/updating the file.
83  static ErrorOr<std::unique_ptr<MemoryBuffer>>
84  getOpenFileSlice(int FD, const char *Filename, uint64_t MapSize,
85                   int64_t Offset, bool IsVolatileSize = false);
86
87  /// Given an already-open file descriptor, read the file and return a
88  /// MemoryBuffer.
89  ///
90  /// \param IsVolatileSize Set to true to indicate that the file size may be
91  /// changing, e.g. when libclang tries to parse while the user is
92  /// editing/updating the file.
93  static ErrorOr<std::unique_ptr<MemoryBuffer>>
94  getOpenFile(int FD, const char *Filename, uint64_t FileSize,
95              bool RequiresNullTerminator = true, bool IsVolatileSize = false);
96
97  /// getMemBuffer - Open the specified memory range as a MemoryBuffer.  Note
98  /// that InputData must be null terminated if RequiresNullTerminator is true.
99  static MemoryBuffer *getMemBuffer(StringRef InputData,
100                                    StringRef BufferName = "",
101                                    bool RequiresNullTerminator = true);
102
103  /// getMemBufferCopy - Open the specified memory range as a MemoryBuffer,
104  /// copying the contents and taking ownership of it.  InputData does not
105  /// have to be null terminated.
106  static MemoryBuffer *getMemBufferCopy(StringRef InputData,
107                                        StringRef BufferName = "");
108
109  /// getNewMemBuffer - Allocate a new MemoryBuffer of the specified size that
110  /// is completely initialized to zeros.  Note that the caller should
111  /// initialize the memory allocated by this method.  The memory is owned by
112  /// the MemoryBuffer object.
113  static MemoryBuffer *getNewMemBuffer(size_t Size, StringRef BufferName = "");
114
115  /// getNewUninitMemBuffer - Allocate a new MemoryBuffer of the specified size
116  /// that is not initialized.  Note that the caller should initialize the
117  /// memory allocated by this method.  The memory is owned by the MemoryBuffer
118  /// object.
119  static MemoryBuffer *getNewUninitMemBuffer(size_t Size,
120                                             StringRef BufferName = "");
121
122  /// Read all of stdin into a file buffer, and return it.
123  static ErrorOr<std::unique_ptr<MemoryBuffer>> getSTDIN();
124
125  /// Open the specified file as a MemoryBuffer, or open stdin if the Filename
126  /// is "-".
127  static ErrorOr<std::unique_ptr<MemoryBuffer>>
128  getFileOrSTDIN(StringRef Filename, int64_t FileSize = -1);
129
130  //===--------------------------------------------------------------------===//
131  // Provided for performance analysis.
132  //===--------------------------------------------------------------------===//
133
134  /// The kind of memory backing used to support the MemoryBuffer.
135  enum BufferKind {
136    MemoryBuffer_Malloc,
137    MemoryBuffer_MMap
138  };
139
140  /// Return information on the memory mechanism used to support the
141  /// MemoryBuffer.
142  virtual BufferKind getBufferKind() const = 0;
143};
144
145// Create wrappers for C Binding types (see CBindingWrapping.h).
146DEFINE_SIMPLE_CONVERSION_FUNCTIONS(MemoryBuffer, LLVMMemoryBufferRef)
147
148} // end namespace llvm
149
150#endif
151