Line data    Source code

       1             : // Copyright (c) 2011, Google Inc.
       2             : // All rights reserved.
       3             : //
       4             : // Redistribution and use in source and binary forms, with or without
       5             : // modification, are permitted provided that the following conditions are
       6             : // met:
       7             : //
       8             : //     * Redistributions of source code must retain the above copyright
       9             : // notice, this list of conditions and the following disclaimer.
      10             : //     * Redistributions in binary form must reproduce the above
      11             : // copyright notice, this list of conditions and the following disclaimer
      12             : // in the documentation and/or other materials provided with the
      13             : // distribution.
      14             : //     * Neither the name of Google Inc. nor the names of its
      15             : // contributors may be used to endorse or promote products derived from
      16             : // this software without specific prior written permission.
      17             : //
      18             : // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
      19             : // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
      20             : // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
      21             : // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
      22             : // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      23             : // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
      24             : // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
      25             : // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
      26             : // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
      27             : // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
      28             : // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      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             : 
      40             : namespace 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.
      45             : class 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           0 :   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           0 :   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_