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.cc: Implement google_breakpad::MemoryMappedFile.
30 // See memory_mapped_file.h for details.
31
32 #ifdef HAVE_CONFIG_H
33 #include <config.h> // Must come first
34 #endif
35
36 #include "common/linux/memory_mapped_file.h"
37
38 #include <fcntl.h>
39 #include <sys/mman.h>
40 #if defined(__ANDROID__)
41 #include <sys/stat.h>
42 #endif
43 #include <unistd.h>
44
45 #include "common/memory_range.h"
46 #include "third_party/lss/linux_syscall_support.h"
47
48 namespace google_breakpad {
49
MemoryMappedFile()50 MemoryMappedFile::MemoryMappedFile() {}
51
MemoryMappedFile(const char * path,size_t offset)52 MemoryMappedFile::MemoryMappedFile(const char* path, size_t offset) {
53 Map(path, offset);
54 }
55
~MemoryMappedFile()56 MemoryMappedFile::~MemoryMappedFile() {
57 Unmap();
58 }
59
60 #include <unistd.h>
61
Map(const char * path,size_t offset)62 bool MemoryMappedFile::Map(const char* path, size_t offset) {
63 Unmap();
64 // Based on https://pubs.opengroup.org/onlinepubs/7908799/xsh/open.html
65 // If O_NONBLOCK is set: The open() function will return without blocking
66 // for the device to be ready or available. Setting this value will provent
67 // hanging if file is not avilable.
68 int fd = sys_open(path, O_RDONLY | O_NONBLOCK, 0);
69 if (fd == -1) {
70 return false;
71 }
72
73 #if defined(__x86_64__) || defined(__aarch64__) || \
74 (defined(__mips__) && _MIPS_SIM == _ABI64) || \
75 (defined(__riscv) && __riscv_xlen == 64)
76
77 struct kernel_stat st;
78 if (sys_fstat(fd, &st) == -1 || st.st_size < 0) {
79 #else
80 struct kernel_stat64 st;
81 if (sys_fstat64(fd, &st) == -1 || st.st_size < 0) {
82 #endif
83 sys_close(fd);
84 return false;
85 }
86
87 // Strangely file size can be negative, but we check above that it is not.
88 size_t file_len = static_cast<size_t>(st.st_size);
89 // If the file does not extend beyond the offset, simply use an empty
90 // MemoryRange and return true. Don't bother to call mmap()
91 // even though mmap() can handle an empty file on some platforms.
92 if (offset >= file_len) {
93 sys_close(fd);
94 return true;
95 }
96
97 size_t content_len = file_len - offset;
98 void* data = sys_mmap(NULL, content_len, PROT_READ, MAP_PRIVATE, fd, offset);
99 sys_close(fd);
100 if (data == MAP_FAILED) {
101 return false;
102 }
103
104 content_.Set(data, content_len);
105 return true;
106 }
107
108 void MemoryMappedFile::Unmap() {
109 if (content_.data()) {
110 sys_munmap(const_cast<uint8_t*>(content_.data()), content_.length());
111 content_.Set(NULL, 0);
112 }
113 }
114
115 } // namespace google_breakpad
116