DataBufferMemoryMap.h revision 24943d2ee8bfaa7cf5893e4709143924157a5c1e 
1//===-- DataBufferMemoryMap.h -----------------------------------*- 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#ifndef liblldb_DataBufferMemoryMap_h_
11#define liblldb_DataBufferMemoryMap_h_
12#if defined(__cplusplus)
13
14
15#include "lldb/lldb-private.h"
16#include "lldb/Core/DataBuffer.h"
17#include "lldb/Core/Error.h"
18#include <string>
19
20namespace lldb_private {
21
22//----------------------------------------------------------------------
23/// @class DataBufferMemoryMap DataBufferMemoryMap.h "lldb/Core/DataBufferMemoryMap.h"
24/// @brief A subclass of DataBuffer that memory maps data.
25///
26/// This class memory maps data and stores any needed data for the
27/// memory mapping in its internal state. Memory map requests are not
28/// required to have any alignment or size constraints, this class will
29/// work around any host OS issues regarding such things.
30///
31/// This class is designed to allow pages to be faulted in as needed and
32/// works well data from large files that won't be accessed all at once.
33//----------------------------------------------------------------------
34class DataBufferMemoryMap : public DataBuffer
35{
36public:
37    //------------------------------------------------------------------
38    /// Default Constructor
39    //------------------------------------------------------------------
40    DataBufferMemoryMap ();
41
42    //------------------------------------------------------------------
43    /// Destructor.
44    ///
45    /// Virtual destructor since this class inherits from a pure virtual
46    /// base class #DataBuffer.
47    //------------------------------------------------------------------
48    virtual
49    ~DataBufferMemoryMap ();
50
51    //------------------------------------------------------------------
52    /// Reverts this object to an empty state by unmapping any memory
53    /// that is currently owned.
54    //------------------------------------------------------------------
55    void
56    Clear ();
57
58    //------------------------------------------------------------------
59    /// @copydoc DataBuffer::GetBytes()
60    //------------------------------------------------------------------
61    virtual uint8_t *
62    GetBytes ();
63
64    //------------------------------------------------------------------
65    /// @copydoc DataBuffer::GetBytes() const
66    //------------------------------------------------------------------
67    virtual const uint8_t *
68    GetBytes () const;
69
70    //------------------------------------------------------------------
71    /// @copydoc DataBuffer::GetByteSize() const
72    //------------------------------------------------------------------
73    virtual size_t
74    GetByteSize () const;
75
76    //------------------------------------------------------------------
77    /// Error get accessor.
78    ///
79    /// @return
80    ///     A const reference to Error object in case memory mapping
81    ///     fails.
82    //------------------------------------------------------------------
83    const Error &
84    GetError() const;
85
86    //------------------------------------------------------------------
87    /// Memory map all or part of a file.
88    ///
89    /// Memory map \a length bytes from \a file starting \a offset
90    /// bytes into the file. If \a length is set to \c SIZE_T_MAX,
91    /// then map as many bytes as possible.
92    ///
93    /// @param[in] file
94    ///     The file specification from which to map data.
95    ///
96    /// @param[in] offset
97    ///     The offset in bytes from the beginning of the file where
98    ///     memory mapping should begin.
99    ///
100    /// @param[in] length
101    ///     The size in bytes that should be mapped starting \a offset
102    ///     bytes into the file. If \a length is \c SIZE_T_MAX, map
103    ///     as many bytes as possible.
104    ///
105    /// @return
106    ///     The number of bytes mapped starting from the \a offset.
107    //------------------------------------------------------------------
108    size_t
109    MemoryMapFromFileSpec (const FileSpec* file,
110                           off_t offset = 0,
111                           size_t length = SIZE_T_MAX);
112
113    //------------------------------------------------------------------
114    /// Memory map all or part of a file.
115    ///
116    /// Memory map \a length bytes from an opened file descriptor \a fd
117    /// starting \a offset bytes into the file. If \a length is set to
118    /// \c SIZE_T_MAX, then map as many bytes as possible.
119    ///
120    /// @param[in] fd
121    ///     The posix file descriptor for an already opened file
122    ///     from which to map data.
123    ///
124    /// @param[in] offset
125    ///     The offset in bytes from the beginning of the file where
126    ///     memory mapping should begin.
127    ///
128    /// @param[in] length
129    ///     The size in bytes that should be mapped starting \a offset
130    ///     bytes into the file. If \a length is \c SIZE_T_MAX, map
131    ///     as many bytes as possible.
132    ///
133    /// @return
134    ///     The number of bytes mapped starting from the \a offset.
135    //------------------------------------------------------------------
136    size_t
137    MemoryMapFromFileDescriptor (int fd, off_t offset = 0, size_t length = SIZE_T_MAX);
138
139protected:
140    //------------------------------------------------------------------
141    // Classes that inherit from DataBufferMemoryMap can see and modify these
142    //------------------------------------------------------------------
143    uint8_t * m_mmap_addr;  ///< The actual pointer that was returned from \c mmap()
144    size_t m_mmap_size;     ///< The actual number of bytes that were mapped when \c mmap() was called
145    uint8_t *m_data;        ///< The data the user requested somewhere within the memory mapped data.
146    size_t m_size;          ///< The size of the data the user got when data was requested
147    Error m_error;      ///< An error object that describes any errors that occurred during the memory mapping process
148
149private:
150    DISALLOW_COPY_AND_ASSIGN (DataBufferMemoryMap);
151};
152
153} // namespace lldb_private
154
155#endif  // #if defined(__cplusplus)
156#endif  // liblldb_DataBufferMemoryMap_h_
157