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