1 // Copyright 2011 Google LLC 2 // 3 // Redistribution and use in source and binary forms, with or without 4 // modification, are permitted provided that the following conditions are 5 // met: 6 // 7 // * Redistributions of source code must retain the above copyright 8 // notice, this list of conditions and the following disclaimer. 9 // * Redistributions in binary form must reproduce the above 10 // copyright notice, this list of conditions and the following disclaimer 11 // in the documentation and/or other materials provided with the 12 // distribution. 13 // * Neither the name of Google LLC nor the names of its 14 // contributors may be used to endorse or promote products derived from 15 // this software without specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29 // memory_mapped_file.h: Define the google_breakpad::MemoryMappedFile 30 // class, which maps a file into memory for read-only access. 31 32 #ifndef COMMON_LINUX_MEMORY_MAPPED_FILE_H_ 33 #define COMMON_LINUX_MEMORY_MAPPED_FILE_H_ 34 35 #include <stddef.h> 36 37 #include "common/memory_range.h" 38 39 namespace google_breakpad { 40 41 // A utility class for mapping a file into memory for read-only access of 42 // the file content. Its implementation avoids calling into libc functions 43 // by directly making system calls for open, close, mmap, and munmap. 44 class MemoryMappedFile { 45 public: 46 MemoryMappedFile(); 47 48 // Constructor that calls Map() to map a file at |path| into memory. 49 // If Map() fails, the object behaves as if it is default constructed. 50 MemoryMappedFile(const char* path, size_t offset); 51 52 MemoryMappedFile(const MemoryMappedFile&) = delete; 53 void operator=(const MemoryMappedFile&) = delete; 54 55 ~MemoryMappedFile(); 56 57 // Maps a file at |path| into memory, which can then be accessed via 58 // content() as a MemoryRange object or via data(), and returns true on 59 // success. Mapping an empty file will succeed but with data() and size() 60 // returning NULL and 0, respectively. An existing mapping is unmapped 61 // before a new mapping is created. 62 bool Map(const char* path, size_t offset); 63 64 // Unmaps the memory for the mapped file. It's a no-op if no file is 65 // mapped. 66 void Unmap(); 67 68 // Returns a MemoryRange object that covers the memory for the mapped 69 // file. The MemoryRange object is empty if no file is mapped. content()70 const MemoryRange& content() const { return content_; } 71 72 // Returns a pointer to the beginning of the memory for the mapped file. 73 // or NULL if no file is mapped or the mapped file is empty. data()74 const void* data() const { return content_.data(); } 75 76 // Returns the size in bytes of the mapped file, or zero if no file 77 // is mapped. size()78 size_t size() const { return content_.length(); } 79 80 private: 81 // Mapped file content as a MemoryRange object. 82 MemoryRange content_; 83 }; 84 85 } // namespace google_breakpad 86 87 #endif // COMMON_LINUX_MEMORY_MAPPED_FILE_H_ 88