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29
30// memory_mapped_file.h: Define the google_breakpad::MemoryMappedFile
31// class, which maps a file into memory for read-only access.
32
33#ifndef COMMON_LINUX_MEMORY_MAPPED_FILE_H_
34#define COMMON_LINUX_MEMORY_MAPPED_FILE_H_
35
36#include <stddef.h>
37#include "common/basictypes.h"
38#include "common/memory_range.h"
39
40namespace google_breakpad {
41
42// A utility class for mapping a file into memory for read-only access of
43// the file content. Its implementation avoids calling into libc functions
44// by directly making system calls for open, close, mmap, and munmap.
45class MemoryMappedFile {
46 public:
47 MemoryMappedFile();
48
49 // Constructor that calls Map() to map a file at |path| into memory.
50 // If Map() fails, the object behaves as if it is default constructed.
51 MemoryMappedFile(const char* path, size_t offset);
52
53 ~MemoryMappedFile();
54
55 // Maps a file at |path| into memory, which can then be accessed via
56 // content() as a MemoryRange object or via data(), and returns true on
57 // success. Mapping an empty file will succeed but with data() and size()
58 // returning NULL and 0, respectively. An existing mapping is unmapped
59 // before a new mapping is created.
60 bool Map(const char* path, size_t offset);
61
62 // Unmaps the memory for the mapped file. It's a no-op if no file is
63 // mapped.
64 void Unmap();
65
66 // Returns a MemoryRange object that covers the memory for the mapped
67 // file. The MemoryRange object is empty if no file is mapped.
68 const MemoryRange& content() const { return content_; }
69
70 // Returns a pointer to the beginning of the memory for the mapped file.
71 // or NULL if no file is mapped or the mapped file is empty.
72 const void* data() const { return content_.data(); }
73
74 // Returns the size in bytes of the mapped file, or zero if no file
75 // is mapped.
76 size_t size() const { return content_.length(); }
77
78 private:
79 // Mapped file content as a MemoryRange object.
80 MemoryRange content_;
81
82 DISALLOW_COPY_AND_ASSIGN(MemoryMappedFile);
83};
84
85} // namespace google_breakpad
86
87#endif // COMMON_LINUX_MEMORY_MAPPED_FILE_H_
88