1// Copyright (c) 2011, Google Inc.
2// All rights reserved.
3//
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5// modification, are permitted provided that the following conditions are
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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
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12// in the documentation and/or other materials provided with the
13// distribution.
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17//
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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,
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28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30// memory_mapped_file.cc: Implement google_breakpad::MemoryMappedFile.
31// See memory_mapped_file.h for details.
32
33#include "common/linux/memory_mapped_file.h"
34
35#include <fcntl.h>
36#include <sys/mman.h>
37#if defined(__ANDROID__)
38#include <sys/stat.h>
39#endif
40#include <unistd.h>
41
42#include "common/memory_range.h"
43#include "third_party/lss/linux_syscall_support.h"
44
45namespace google_breakpad {
46
47MemoryMappedFile::MemoryMappedFile() {}
48
49MemoryMappedFile::MemoryMappedFile(const char* path, size_t offset) {
50  Map(path, offset);
51}
52
53MemoryMappedFile::~MemoryMappedFile() {
54  Unmap();
55}
56
57#include <unistd.h>
58
59bool MemoryMappedFile::Map(const char* path, size_t offset) {
60  Unmap();
61
62  int fd = sys_open(path, O_RDONLY, 0);
63  if (fd == -1) {
64    return false;
65  }
66
67#if defined(__x86_64__) || defined(__aarch64__) || \
68   (defined(__mips__) && _MIPS_SIM == _ABI64)
69
70  struct kernel_stat st;
71  if (sys_fstat(fd, &st) == -1 || st.st_size < 0) {
72#else
73  struct kernel_stat64 st;
74  if (sys_fstat64(fd, &st) == -1 || st.st_size < 0) {
75#endif
76    sys_close(fd);
77    return false;
78  }
79
80  // Strangely file size can be negative, but we check above that it is not.
81  size_t file_len = static_cast<size_t>(st.st_size);
82  // If the file does not extend beyond the offset, simply use an empty
83  // MemoryRange and return true. Don't bother to call mmap()
84  // even though mmap() can handle an empty file on some platforms.
85  if (offset >= file_len) {
86    sys_close(fd);
87    return true;
88  }
89
90#if defined(__x86_64__) || defined(__aarch64__) || \
91   (defined(__mips__) && _MIPS_SIM == _ABI64)
92  void* data = sys_mmap(NULL, file_len, PROT_READ, MAP_PRIVATE, fd, offset);
93#else
94  if ((offset & 4095) != 0) {
95    // Not page aligned.
96    sys_close(fd);
97    return false;
98  }
99  void* data = sys_mmap2(
100      NULL, file_len, PROT_READ, MAP_PRIVATE, fd, offset >> 12);
101#endif
102  sys_close(fd);
103  if (data == MAP_FAILED) {
104    return false;
105  }
106
107  content_.Set(data, file_len - offset);
108  return true;
109}
110
111void MemoryMappedFile::Unmap() {
112  if (content_.data()) {
113    sys_munmap(const_cast<uint8_t*>(content_.data()), content_.length());
114    content_.Set(NULL, 0);
115  }
116}
117
118}  // namespace google_breakpad
119