1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "base/memory/shared_memory.h" 6 7 #include <errno.h> 8 #include <fcntl.h> 9 #include <sys/mman.h> 10 #include <sys/stat.h> 11 #include <unistd.h> 12 13 #include <limits> 14 15 #include "base/logging.h" 16 17 namespace base { 18 19 SharedMemory::SharedMemory() 20 : mapped_file_(-1), 21 inode_(0), 22 mapped_size_(0), 23 memory_(NULL), 24 read_only_(false), 25 requested_size_(0) { 26 } 27 28 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only) 29 : mapped_file_(handle.fd), 30 inode_(0), 31 mapped_size_(0), 32 memory_(NULL), 33 read_only_(read_only), 34 requested_size_(0) { 35 } 36 37 SharedMemory::SharedMemory(SharedMemoryHandle handle, bool read_only, 38 ProcessHandle process) 39 : mapped_file_(handle.fd), 40 inode_(0), 41 mapped_size_(0), 42 memory_(NULL), 43 read_only_(read_only), 44 requested_size_(0) { 45 NOTREACHED(); 46 } 47 48 SharedMemory::~SharedMemory() { 49 Close(); 50 } 51 52 // static 53 bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) { 54 return handle.fd >= 0; 55 } 56 57 // static 58 SharedMemoryHandle SharedMemory::NULLHandle() { 59 return SharedMemoryHandle(); 60 } 61 62 // static 63 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) { 64 DCHECK_GE(handle.fd, 0); 65 if (close(handle.fd) < 0) 66 DPLOG(ERROR) << "close"; 67 } 68 69 bool SharedMemory::CreateAndMapAnonymous(size_t size) { 70 // Untrusted code can't create descriptors or handles. 71 return false; 72 } 73 74 bool SharedMemory::Create(const SharedMemoryCreateOptions& options) { 75 // Untrusted code can't create descriptors or handles. 76 return false; 77 } 78 79 bool SharedMemory::Delete(const std::string& name) { 80 return false; 81 } 82 83 bool SharedMemory::Open(const std::string& name, bool read_only) { 84 return false; 85 } 86 87 bool SharedMemory::MapAt(off_t offset, size_t bytes) { 88 if (mapped_file_ == -1) 89 return false; 90 91 if (bytes > static_cast<size_t>(std::numeric_limits<int>::max())) 92 return false; 93 94 if (memory_) 95 return false; 96 97 memory_ = mmap(NULL, bytes, PROT_READ | (read_only_ ? 0 : PROT_WRITE), 98 MAP_SHARED, mapped_file_, offset); 99 100 bool mmap_succeeded = memory_ != MAP_FAILED && memory_ != NULL; 101 if (mmap_succeeded) { 102 mapped_size_ = bytes; 103 DCHECK_EQ(0U, reinterpret_cast<uintptr_t>(memory_) & 104 (SharedMemory::MAP_MINIMUM_ALIGNMENT - 1)); 105 } else { 106 memory_ = NULL; 107 } 108 109 return mmap_succeeded; 110 } 111 112 bool SharedMemory::Unmap() { 113 if (memory_ == NULL) 114 return false; 115 116 if (munmap(memory_, mapped_size_) < 0) 117 DPLOG(ERROR) << "munmap"; 118 memory_ = NULL; 119 mapped_size_ = 0; 120 return true; 121 } 122 123 SharedMemoryHandle SharedMemory::handle() const { 124 return FileDescriptor(mapped_file_, false); 125 } 126 127 void SharedMemory::Close() { 128 Unmap(); 129 if (mapped_file_ > 0) { 130 if (close(mapped_file_) < 0) 131 DPLOG(ERROR) << "close"; 132 mapped_file_ = -1; 133 } 134 } 135 136 void SharedMemory::LockDeprecated() { 137 NOTIMPLEMENTED(); 138 } 139 140 void SharedMemory::UnlockDeprecated() { 141 NOTIMPLEMENTED(); 142 } 143 144 bool SharedMemory::ShareToProcessCommon(ProcessHandle process, 145 SharedMemoryHandle *new_handle, 146 bool close_self, 147 ShareMode share_mode) { 148 if (share_mode == SHARE_READONLY) { 149 // Untrusted code can't create descriptors or handles, which is needed to 150 // drop permissions. 151 return false; 152 } 153 const int new_fd = dup(mapped_file_); 154 if (new_fd < 0) { 155 DPLOG(ERROR) << "dup() failed."; 156 return false; 157 } 158 159 new_handle->fd = new_fd; 160 new_handle->auto_close = true; 161 162 if (close_self) 163 Close(); 164 return true; 165 } 166 167 } // namespace base 168