Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2022 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #include "file_utils.h" |
| 18 | |
| 19 | #include <fcntl.h> |
| 20 | #include <sys/stat.h> |
| 21 | #include <sys/types.h> |
| 22 | #include <unistd.h> |
| 23 | |
| 24 | #include <filesystem> |
| 25 | #include <memory> |
| 26 | #include <string> |
| 27 | #include <string_view> |
| 28 | #include <system_error> |
| 29 | #include <utility> |
| 30 | |
| 31 | #include "aidl/com/android/server/art/FsPermission.h" |
| 32 | #include "android-base/errors.h" |
| 33 | #include "android-base/logging.h" |
| 34 | #include "android-base/result.h" |
| 35 | #include "android-base/scopeguard.h" |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 36 | #include "base/os.h" |
| 37 | #include "base/unix_file/fd_file.h" |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 38 | #include "fmt/format.h" |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 39 | |
| 40 | namespace art { |
| 41 | namespace artd { |
| 42 | |
| 43 | namespace { |
| 44 | |
| 45 | using ::aidl::com::android::server::art::FsPermission; |
| 46 | using ::android::base::make_scope_guard; |
| 47 | using ::android::base::Result; |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 48 | |
| 49 | using ::fmt::literals::operator""_format; // NOLINT |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 50 | |
| 51 | void UnlinkIfExists(const std::string& path) { |
| 52 | std::error_code ec; |
| 53 | if (!std::filesystem::remove(path, ec)) { |
| 54 | if (ec.value() != ENOENT) { |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 55 | LOG(WARNING) << "Failed to remove file '{}': {}"_format(path, ec.message()); |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 56 | } |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | } // namespace |
| 61 | |
| 62 | Result<std::unique_ptr<NewFile>> NewFile::Create(const std::string& path, |
| 63 | const FsPermission& fs_permission) { |
| 64 | std::unique_ptr<NewFile> output_file(new NewFile(path, fs_permission)); |
| 65 | OR_RETURN(output_file->Init()); |
| 66 | return output_file; |
| 67 | } |
| 68 | |
| 69 | NewFile::~NewFile() { Cleanup(); } |
| 70 | |
| 71 | Result<void> NewFile::Keep() { |
| 72 | if (close(std::exchange(fd_, -1)) != 0) { |
| 73 | return ErrnoErrorf("Failed to close file '{}'", temp_path_); |
| 74 | } |
| 75 | return {}; |
| 76 | } |
| 77 | |
| 78 | Result<void> NewFile::CommitOrAbandon() { |
| 79 | auto cleanup = make_scope_guard([this] { Unlink(); }); |
| 80 | OR_RETURN(Keep()); |
| 81 | std::error_code ec; |
| 82 | std::filesystem::rename(temp_path_, final_path_, ec); |
| 83 | if (ec) { |
| 84 | return Errorf( |
| 85 | "Failed to move new file '{}' to path '{}': {}", temp_path_, final_path_, ec.message()); |
| 86 | } |
| 87 | cleanup.Disable(); |
| 88 | committed_ = true; |
| 89 | return {}; |
| 90 | } |
| 91 | |
| 92 | void NewFile::Cleanup() { |
| 93 | if (fd_ >= 0) { |
| 94 | Unlink(); |
| 95 | if (close(std::exchange(fd_, -1)) != 0) { |
| 96 | // Nothing we can do. If the file is already unlinked, it will go away when the process exits. |
| 97 | PLOG(WARNING) << "Failed to close file '" << temp_path_ << "'"; |
| 98 | } |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | Result<void> NewFile::Init() { |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 103 | mode_t mode = FileFsPermissionToMode(fs_permission_); |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 104 | // "<path_>.XXXXXX.tmp". |
| 105 | temp_path_ = BuildTempPath(final_path_, "XXXXXX"); |
| 106 | fd_ = mkstemps(temp_path_.data(), /*suffixlen=*/4); |
| 107 | if (fd_ < 0) { |
| 108 | return ErrnoErrorf("Failed to create temp file for '{}'", final_path_); |
| 109 | } |
| 110 | temp_id_ = temp_path_.substr(/*pos=*/final_path_.length() + 1, /*count=*/6); |
| 111 | if (fchmod(fd_, mode) != 0) { |
| 112 | return ErrnoErrorf("Failed to chmod file '{}'", temp_path_); |
| 113 | } |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 114 | OR_RETURN(Chown(temp_path_, fs_permission_)); |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 115 | return {}; |
| 116 | } |
| 117 | |
| 118 | void NewFile::Unlink() { |
| 119 | // This should never fail. We were able to create the file, so we should be able to remove it. |
| 120 | UnlinkIfExists(temp_path_); |
| 121 | } |
| 122 | |
| 123 | Result<void> NewFile::CommitAllOrAbandon(const std::vector<NewFile*>& files_to_commit, |
| 124 | const std::vector<std::string_view>& files_to_remove) { |
| 125 | std::vector<std::pair<std::string_view, std::string>> moved_files; |
| 126 | |
| 127 | auto cleanup = make_scope_guard([&]() { |
| 128 | // Clean up new files. |
| 129 | for (NewFile* new_file : files_to_commit) { |
| 130 | if (new_file->committed_) { |
| 131 | UnlinkIfExists(new_file->FinalPath()); |
| 132 | } else { |
| 133 | new_file->Cleanup(); |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | // Move old files back. |
| 138 | for (const auto& [original_path, temp_path] : moved_files) { |
| 139 | std::error_code ec; |
| 140 | std::filesystem::rename(temp_path, original_path, ec); |
| 141 | if (ec) { |
| 142 | // This should never happen. We were able to move the file from `original_path` to |
| 143 | // `temp_path`. We should be able to move it back. |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 144 | LOG(WARNING) << "Failed to move old file '{}' back from temporary path '{}': {}"_format( |
| 145 | original_path, temp_path, ec.message()); |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 146 | } |
| 147 | } |
| 148 | }); |
| 149 | |
| 150 | // Move old files to temporary locations. |
| 151 | std::vector<std::string_view> all_files_to_remove; |
| 152 | for (NewFile* file : files_to_commit) { |
| 153 | all_files_to_remove.push_back(file->FinalPath()); |
| 154 | } |
| 155 | all_files_to_remove.insert( |
| 156 | all_files_to_remove.end(), files_to_remove.begin(), files_to_remove.end()); |
| 157 | |
| 158 | for (std::string_view original_path : all_files_to_remove) { |
| 159 | std::error_code ec; |
| 160 | std::filesystem::file_status status = std::filesystem::status(original_path, ec); |
| 161 | if (!std::filesystem::status_known(status)) { |
| 162 | return Errorf("Failed to get status of old file '{}': {}", original_path, ec.message()); |
| 163 | } |
| 164 | if (std::filesystem::is_directory(status)) { |
| 165 | return ErrnoErrorf("Old file '{}' is a directory", original_path); |
| 166 | } |
| 167 | if (std::filesystem::exists(status)) { |
| 168 | std::string temp_path = BuildTempPath(original_path, "XXXXXX"); |
| 169 | int fd = mkstemps(temp_path.data(), /*suffixlen=*/4); |
| 170 | if (fd < 0) { |
| 171 | return ErrnoErrorf("Failed to create temporary path for old file '{}'", original_path); |
| 172 | } |
| 173 | close(fd); |
| 174 | |
| 175 | std::filesystem::rename(original_path, temp_path, ec); |
| 176 | if (ec) { |
| 177 | UnlinkIfExists(temp_path); |
| 178 | return Errorf("Failed to move old file '{}' to temporary path '{}': {}", |
| 179 | original_path, |
| 180 | temp_path, |
| 181 | ec.message()); |
| 182 | } |
| 183 | |
| 184 | moved_files.push_back({original_path, std::move(temp_path)}); |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | // Commit new files. |
| 189 | for (NewFile* file : files_to_commit) { |
| 190 | OR_RETURN(file->CommitOrAbandon()); |
| 191 | } |
| 192 | |
| 193 | cleanup.Disable(); |
| 194 | |
| 195 | // Clean up old files. |
| 196 | for (const auto& [original_path, temp_path] : moved_files) { |
| 197 | // This should never fail. We were able to move the file to `temp_path`. We should be able to |
| 198 | // remove it. |
| 199 | UnlinkIfExists(temp_path); |
| 200 | } |
| 201 | |
| 202 | return {}; |
| 203 | } |
| 204 | |
| 205 | std::string NewFile::BuildTempPath(std::string_view final_path, const std::string& id) { |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 206 | return "{}.{}.tmp"_format(final_path, id); |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 207 | } |
| 208 | |
| 209 | Result<std::unique_ptr<File>> OpenFileForReading(const std::string& path) { |
| 210 | std::unique_ptr<File> file(OS::OpenFileForReading(path.c_str())); |
| 211 | if (file == nullptr) { |
| 212 | return ErrnoErrorf("Failed to open file '{}'", path); |
| 213 | } |
| 214 | return file; |
| 215 | } |
| 216 | |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 217 | mode_t FileFsPermissionToMode(const FsPermission& fs_permission) { |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 218 | return S_IRUSR | S_IWUSR | S_IRGRP | (fs_permission.isOtherReadable ? S_IROTH : 0) | |
| 219 | (fs_permission.isOtherExecutable ? S_IXOTH : 0); |
| 220 | } |
| 221 | |
Jiakai Zhang | 3aaecf0 | 2022-08-10 15:35:28 +0100 | [diff] [blame] | 222 | mode_t DirFsPermissionToMode(const FsPermission& fs_permission) { |
| 223 | return FileFsPermissionToMode(fs_permission) | S_IXUSR | S_IXGRP; |
| 224 | } |
| 225 | |
| 226 | Result<void> Chown(const std::string& path, const FsPermission& fs_permission) { |
| 227 | if (fs_permission.uid < 0 && fs_permission.gid < 0) { |
| 228 | // Keep the default owner. |
| 229 | } else if (fs_permission.uid < 0 || fs_permission.gid < 0) { |
| 230 | return Errorf("uid and gid must be both non-negative or both negative, got {} and {}.", |
| 231 | fs_permission.uid, |
| 232 | fs_permission.gid); |
| 233 | } |
| 234 | if (chown(path.c_str(), fs_permission.uid, fs_permission.gid) != 0) { |
| 235 | return ErrnoErrorf("Failed to chown '{}'", path); |
| 236 | } |
| 237 | return {}; |
| 238 | } |
| 239 | |
Jiakai Zhang | a2ba696 | 2022-07-04 16:56:12 +0100 | [diff] [blame] | 240 | } // namespace artd |
| 241 | } // namespace art |