1 /* 2 * Filesystem resource registry incorporating opening functionality. 3 * 4 * Copyright (C) 2021, 2022 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 * Boston, MA 02110-1301, USA 20 */ 21 22 #include "directory_resource.h" 23 #include "file_pager.h" 24 #include "resource_registry.h" 25 26 #include <systypes/fcntl.h> 27 28 29 30 /* The resource registry provides a memory page collection to the page mappers 31 it creates. */ 32 33 ResourceRegistry::ResourceRegistry(Pages *pages) 34 : _pages(pages) 35 { 36 } 37 38 39 40 /* Make a directory provider. */ 41 42 long ResourceRegistry::make_directory_provider(FileOpening *opening, 43 flags_t flags, 44 fileid_t fileid, 45 Provider **provider) 46 { 47 /* Make an accessor and a provider to encapsulate it. */ 48 49 DirectoryAccessor *accessor; 50 long err = opening->make_directory_accessor(flags, fileid, &accessor); 51 52 if (err) 53 return err; 54 55 *provider = new DirectoryProvider(fileid, this, accessor); 56 return L4_EOK; 57 } 58 59 /* Make a file provider. */ 60 61 long ResourceRegistry::make_file_provider(FileOpening *opening, 62 flags_t flags, 63 fileid_t fileid, 64 Provider **provider) 65 { 66 /* Make an accessor, page mapper, and a provider to encapsulate them. */ 67 68 Accessor *accessor; 69 long err = opening->make_accessor(flags, fileid, &accessor); 70 71 if (err) 72 return err; 73 74 PageMapper *mapper = new PageMapper(accessor, _pages); 75 *provider = new FileProvider(fileid, this, mapper); 76 return L4_EOK; 77 } 78 79 /* Make a provider of the appropriate type. */ 80 81 long ResourceRegistry::make_provider(FileOpening *opening, 82 flags_t flags, 83 fileid_t fileid, 84 Provider **provider) 85 { 86 long err = -L4_EIO; 87 88 if (opening->accessing_directory(flags, fileid)) 89 err = make_directory_provider(opening, flags, fileid, provider); 90 else if (opening->accessing_file(flags, fileid)) 91 err = make_file_provider(opening, flags, fileid, provider); 92 93 if (err) 94 return err; 95 96 /* Register the provider. */ 97 98 set(fileid, *provider); 99 return L4_EOK; 100 } 101 102 103 104 /* Obtain any active provider for the given 'fileid'. */ 105 106 long ResourceRegistry::find_provider(fileid_t fileid, Provider **provider) 107 { 108 /* Obtain any registered provider. */ 109 110 Accountable *accountable = get(fileid); 111 112 if (accountable != NULL) 113 { 114 *provider = dynamic_cast<Provider *>(accountable); 115 116 if ((*provider) != NULL) 117 return L4_EOK; 118 else 119 return -L4_EIO; 120 } 121 122 return -L4_ENOENT; 123 } 124 125 126 127 /* Return a resource for a filesystem object. */ 128 129 long ResourceRegistry::get_resource(FileOpening *opening, const char *path, 130 flags_t flags, offset_t *size, 131 object_flags_t *object_flags, 132 Resource **resource) 133 { 134 std::lock_guard<std::mutex> guard(_lock); 135 136 /* Obtain an identifier for the object, even for new files (subject to use 137 of the appropriate flag). This also checks the access rights for any 138 configured user. */ 139 140 fileid_t fileid; 141 long err = opening->get_fileid(path, flags, &fileid); 142 143 if (err) 144 return err; 145 146 /* Obtain a provider for the object. */ 147 148 Provider *provider; 149 err = find_provider(fileid, &provider); 150 151 /* Make a new provider if necessary. */ 152 153 if (err == -L4_ENOENT) 154 err = make_provider(opening, flags, fileid, &provider); 155 156 if (err) 157 return err; 158 159 /* Make a resource for the provider. */ 160 161 return provider->make_resource(flags, size, object_flags, resource); 162 } 163 164 /* Request the removal of a filesystem object through any active provider or 165 perform the direct removal of any inactive object. */ 166 167 long ResourceRegistry::remove_provider(FileOpening *opening, const char *path) 168 { 169 std::lock_guard<std::mutex> guard(_lock); 170 171 /* Obtain an identifier for any recognised object. This also checks the 172 access rights for any configured user. */ 173 174 fileid_t fileid; 175 long err = opening->get_fileid(path, 0, &fileid); 176 177 if (err) 178 return err; 179 180 return _remove_provider(opening, path, fileid); 181 } 182 183 long ResourceRegistry::_remove_provider(FileOpening *opening, const char *path, 184 fileid_t fileid) 185 { 186 /* Obtain a provider for the object. */ 187 188 Provider *provider; 189 long err = find_provider(fileid, &provider), lookup_err = err; 190 191 if (err && (err != -L4_ENOENT)) 192 return err; 193 194 fileid_t parent_fileid; 195 196 err = opening->get_parent(path, &parent_fileid); 197 198 if (err) 199 return err; 200 201 /* Test for an empty directory. 202 NOTE: A descriptive error should be communicated. */ 203 204 if (opening->accessing_directory(0, fileid) && !opening->directory_is_empty(fileid)) 205 return -L4_EIO; 206 207 /* Unlink the object regardless of whether it will be removed. */ 208 209 err = opening->unlink_object(parent_fileid, fileid); 210 211 if (err) 212 return err; 213 214 /* Without a provider being active, remove the object directly. */ 215 216 if (lookup_err) 217 return opening->remove_object(fileid); 218 219 /* With a provider active, request the object's removal upon closure. */ 220 221 provider->remove_pending(true); 222 return L4_EOK; 223 } 224 225 /* Request the renaming of a filesystem object. */ 226 227 long ResourceRegistry::rename_provider(FileOpening *opening, const char *source, 228 const char *target) 229 { 230 std::lock_guard<std::mutex> guard(_lock); 231 232 long err; 233 fileid_t source_fileid, target_fileid; 234 235 /* Obtain an identifier for any recognised object. This also checks the 236 access rights for any configured user. */ 237 238 err = opening->get_fileid(source, 0, &source_fileid); 239 240 if (err) 241 return err; 242 243 /* If source is a directory, the target must be a new directory or an empty 244 directory. An empty directory will be replaced by the source 245 directory. */ 246 247 if (opening->accessing_directory(0, source_fileid)) 248 { 249 err = opening->get_fileid(target, 0, &target_fileid); 250 251 if (err && (err != -L4_ENOENT)) 252 return err; 253 254 /* Any existing directory must be empty. */ 255 256 if (!err) 257 { 258 /* NOTE: Should really use the equivalent of ENOTDIR. */ 259 260 if (!opening->accessing_directory(0, target_fileid)) 261 return -L4_EIO; 262 263 /* NOTE: Test for empty directory. */ 264 265 /* The existing directory will be removed. */ 266 267 err = _remove_provider(opening, target, target_fileid); 268 269 if (err) 270 return err; 271 } 272 273 /* The source directory is moved within the filesystem to the parent of 274 the indicated target. */ 275 276 return opening->rename_object(source, target); 277 } 278 279 /* If source is a file, the target must be a new or existing file, not a 280 directory. An existing file will be replaced. */ 281 282 else if (opening->accessing_file(0, source_fileid)) 283 { 284 err = opening->get_fileid(target, 0, &target_fileid); 285 286 if (err && (err != -L4_ENOENT)) 287 return err; 288 289 if (!err) 290 { 291 /* NOTE: Should really use the equivalent of EISDIR. */ 292 293 if (!opening->accessing_file(0, target_fileid)) 294 return -L4_EIO; 295 296 /* The existing file will be removed. */ 297 298 err = _remove_provider(opening, target, target_fileid); 299 300 if (err) 301 return err; 302 } 303 304 /* The source file is moved within the filesystem to the parent of the 305 indicated target. */ 306 307 return opening->rename_object(source, target); 308 } 309 310 /* NOTE: Other object types are to be supported. */ 311 312 else 313 return -L4_EIO; 314 } 315 316 // vim: tabstop=4 expandtab shiftwidth=4