1 /* 2 * Filesystem client functions. 3 * 4 * Copyright (C) 2018, 2019, 2020, 2021 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 <l4/re/env.h> 23 24 #include <stdio.h> 25 #include <stdlib.h> 26 #include <string.h> 27 28 #include <systypes/fcntl.h> 29 30 #include "client.h" 31 32 33 34 /* Default size of pipe regions. */ 35 36 const offset_t DEFAULT_PIPE_SIZE = 4096; 37 38 /* Size of the core member region of a directory entry structure. */ 39 40 const offset_t DIRENT_CORE_SIZE = (sizeof(struct dirent) - sizeof(((struct dirent *) 0)->d_name)); 41 42 43 44 /* Access the given position and synchronise state with the file object. Pipe 45 objects may return busy conditions indicating that the desired access cannot 46 yet be fulfilled. */ 47 48 static long _access(file_t *file, offset_t position) 49 { 50 long err; 51 52 if (file->object_flags & OBJECT_SUPPORTS_MMAP) 53 { 54 /* Where the position is outside the current region, re-map. */ 55 56 if ((position < file->start_pos) || (position >= file->end_pos)) 57 { 58 if (file_mmap(file, position, file_span(file))) 59 return -L4_EIO; 60 } 61 62 /* Otherwise, flush any written data in the current region and update the 63 file size details. */ 64 65 else 66 { 67 err = client_flush(file); 68 if (err) 69 return err; 70 } 71 72 /* Update the current data offset. */ 73 74 file->data_current = position - file->start_pos; 75 76 return L4_EOK; 77 } 78 else 79 { 80 /* Handle the initial condition with no current region. */ 81 82 if (file->memory == NULL) 83 { 84 err = client_current_region(file); 85 if (err) 86 return err; 87 } 88 89 /* Strict conditions for region navigation in pipes. */ 90 91 if ((position < file->start_pos) || (position > file->end_pos)) 92 { 93 return -L4_EIO; 94 } 95 96 /* The next region is only available at the end of the mapped memory. */ 97 98 else if (position == file->end_pos) 99 { 100 err = client_next_region(file); 101 if (err) 102 return err; 103 104 file->data_current = 0; 105 return L4_EOK; 106 } 107 108 /* Within the current pipe region, synchronise with the pipe object. */ 109 110 else 111 return client_current_region(file); 112 } 113 } 114 115 116 117 /* Return whether an operation on file should block for more content or more 118 space. A file must be configured for blocking, not be closed, and must either 119 be lacking content (if reading) or space (if writing). */ 120 121 static int _operation_blocking(file_t *file, int reading) 122 { 123 return (file->can_block && !(file->notifications & NOTIFY_PEER_CLOSED) && ( 124 (reading && !file_data_available(file)) || 125 (!reading && !file_data_space(file)))); 126 } 127 128 129 130 /* Return whether an access could occur, blocking if necessary. */ 131 132 static int _access_blocking(file_t *file, offset_t position, int reading) 133 { 134 long err; 135 136 /* Attempt to access the position, handling an error condition or a blocking 137 condition. */ 138 139 while ((err = _access(file, position)) || _operation_blocking(file, reading)) 140 { 141 position = file->data_current; 142 143 /* Exit if blocking is not configured or suitable. */ 144 145 if ((err && (err != -L4_EBUSY)) || !file->can_block) 146 return 0; 147 148 /* Handle an inability to access by blocking, exiting if waiting failed. */ 149 150 if (client_wait_file(file, client_notifier_task())) 151 return 0; 152 } 153 154 return 1; 155 } 156 157 158 159 /* Ensure that memory is mapped for accessing the given file, using the 160 indicated count as a region size hint. */ 161 162 static void *_map_memory(file_t *file, offset_t count) 163 { 164 if (file->memory == NULL) 165 { 166 if (file->object_flags & OBJECT_SUPPORTS_MMAP) 167 return client_mmap(file, client_tell(file), count); 168 else if (pipe_current(file)) 169 return NULL; 170 } 171 172 return file->memory; 173 } 174 175 176 177 /* Open a file opening object. */ 178 179 l4_cap_idx_t client_open_for_user(user_t user) 180 { 181 l4_cap_idx_t server = l4re_env_get_cap("server"); 182 183 return client_open_for_user_using(user, server); 184 } 185 186 /* Open a file opening object via a named capability. */ 187 188 l4_cap_idx_t client_open_for_user_using(user_t user, l4_cap_idx_t server) 189 { 190 if (l4_is_invalid_cap(server)) 191 return L4_INVALID_CAP; 192 193 l4_cap_idx_t opener; 194 long err = file_open_for_user(user, server, &opener); 195 196 if (err) 197 return L4_INVALID_CAP; 198 199 return opener; 200 } 201 202 203 204 /* Close a filesystem object. */ 205 206 void client_close(file_t *file) 207 { 208 if (file == NULL) 209 return; 210 211 file_flush(file); 212 file_close(file); 213 free(file); 214 } 215 216 217 218 /* Open a filesystem object. */ 219 220 file_t *client_open(const char *name, flags_t flags) 221 { 222 l4_cap_idx_t server = l4re_env_get_cap("server"); 223 224 return client_open_using(name, flags, server); 225 } 226 227 /* Open a filesystem object via a named capability. */ 228 229 file_t *client_open_using(const char *name, flags_t flags, l4_cap_idx_t server) 230 { 231 if (l4_is_invalid_cap(server)) 232 return NULL; 233 234 file_t *file = (file_t *) malloc(sizeof(file_t)); 235 236 if (file == NULL) 237 return NULL; 238 239 if (file_open(file, name, flags, server)) 240 { 241 free(file); 242 return NULL; 243 } 244 245 return file; 246 } 247 248 249 250 /* Open a directory listing stream via the given directory. */ 251 252 file_t *client_opendir(file_t *file) 253 { 254 if (file == NULL) 255 return NULL; 256 257 file_t *reader = (file_t *) malloc(sizeof(file_t)); 258 259 if (reader == NULL) 260 return NULL; 261 262 long err = directory_opendir(file, reader); 263 264 if (err) 265 return NULL; 266 267 /* Set blocking read mode to be able to conveniently read directory entries 268 from the stream. */ 269 270 if (client_set_blocking(reader, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED)) 271 { 272 client_close(reader); 273 return NULL; 274 } 275 276 return reader; 277 } 278 279 280 281 /* Open a pipe object. */ 282 283 long client_pipe(file_t **reader, file_t **writer, flags_t flags) 284 { 285 l4_cap_idx_t server = l4re_env_get_cap("pipes"); 286 287 return client_pipe_using(reader, writer, flags, server); 288 } 289 290 long client_pipe_using(file_t **reader, file_t **writer, flags_t flags, l4_cap_idx_t server) 291 { 292 if (l4_is_invalid_cap(server)) 293 return -L4_EINVAL; 294 295 *reader = (file_t *) malloc(sizeof(file_t)); 296 297 if (*reader == NULL) 298 return -L4_ENOMEM; 299 300 *writer = (file_t *) malloc(sizeof(file_t)); 301 302 if (*writer == NULL) 303 { 304 free(*reader); 305 return -L4_ENOMEM; 306 } 307 308 long err = pipe_open(DEFAULT_PIPE_SIZE, *reader, *writer, server); 309 310 /* Set blocking if successful and non-blocking is not indicated. */ 311 312 if (!err && !(flags & O_NONBLOCK)) 313 { 314 err = client_set_blocking(*reader, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED); 315 if (!err) 316 err = client_set_blocking(*writer, NOTIFY_SPACE_AVAILABLE | NOTIFY_PEER_CLOSED); 317 } 318 319 if (err) 320 { 321 free(*reader); 322 free(*writer); 323 } 324 325 return err; 326 } 327 328 329 330 /* Obtain the current region of a pipe. */ 331 332 long client_current_region(file_t *file) 333 { 334 if (file == NULL) 335 return -L4_EINVAL; 336 337 return pipe_current(file); 338 } 339 340 341 342 /* Flush data explicitly to the filesystem object. */ 343 344 long client_flush(file_t *file) 345 { 346 if (file == NULL) 347 return -L4_EINVAL; 348 349 /* Flush and retain most buffer settings. */ 350 351 return file_flush(file); 352 } 353 354 355 356 /* Map a memory region to a file. */ 357 358 void *client_mmap(file_t *file, offset_t position, offset_t length) 359 { 360 if ((file == NULL) || (file_mmap(file, position, length))) 361 return NULL; 362 363 return file->memory; 364 } 365 366 367 368 /* Obtain the next region of a pipe. */ 369 370 long client_next_region(file_t *file) 371 { 372 if (file == NULL) 373 return -L4_EINVAL; 374 375 return pipe_next(file); 376 } 377 378 379 380 /* Close a notifier object. */ 381 382 void client_notifier_close(file_notifier_t *notifier) 383 { 384 file_notify_close(notifier); 385 } 386 387 /* Obtain a local notifier object. */ 388 389 file_notifier_t *client_notifier_local() 390 { 391 return file_notify_local(); 392 } 393 394 /* Obtain a task-wide notifier object. */ 395 396 file_notifier_t *client_notifier_task() 397 { 398 return file_notify_task(); 399 } 400 401 402 403 /* Read a directory entry. This must be freed by the caller after use. */ 404 405 struct dirent *client_readdir(file_t *file) 406 { 407 char buffer[DIRENT_CORE_SIZE]; 408 offset_t nread = client_read(file, buffer, DIRENT_CORE_SIZE); 409 410 /* Stop if no new structure can be successfully read. */ 411 412 if (nread != DIRENT_CORE_SIZE) 413 return NULL; 414 415 struct dirent *dirent = (struct dirent *) buffer; 416 offset_t remaining = dirent->d_reclen - DIRENT_CORE_SIZE; 417 418 /* Allocate a buffer for the complete structure. */ 419 420 char *entry = (char *) calloc(DIRENT_CORE_SIZE + remaining, sizeof(char)); 421 422 if (entry == NULL) 423 return NULL; 424 425 /* Copy the start of the entry into a new buffer. */ 426 427 memcpy(entry, buffer, DIRENT_CORE_SIZE); 428 429 /* Append to the entry buffer. */ 430 431 char *current = entry + DIRENT_CORE_SIZE; 432 433 nread = client_read(file, current, remaining); 434 435 /* Stop if no complete structure can be successfully read. */ 436 437 if (nread != remaining) 438 { 439 free(entry); 440 return NULL; 441 } 442 443 return (struct dirent *) entry; 444 } 445 446 447 448 /* Read from the filesystem object into the buffer provided. */ 449 450 offset_t client_read(file_t *file, void *buf, offset_t count) 451 { 452 if (file == NULL) 453 return 0; 454 455 /* Map memory if none has been mapped so far. */ 456 457 if (_map_memory(file, count) == NULL) 458 return 0; 459 460 /* Amount available in the descriptor buffer already. */ 461 462 offset_t available = file_data_available(file); 463 offset_t to_transfer, total = 0; 464 465 while (count > 0) 466 { 467 /* If there is no data, try and obtain more data. */ 468 469 if (!available) 470 { 471 /* Flush any unwritten data, preparing to read from the file position at 472 the end of the data, and returning if no new data is available. */ 473 474 if (!_access_blocking(file, file_data_end_position(file), 1)) 475 break; 476 477 available = file_data_available(file); 478 479 if (!available) 480 break; 481 } 482 483 /* Transfer data into the supplied buffer. */ 484 485 to_transfer = available <= count ? available : count; 486 487 file_data_read(file, (char *) buf, to_transfer); 488 489 /* Update counters. */ 490 491 available -= to_transfer; 492 493 count -= to_transfer; 494 total += to_transfer; 495 496 buf = ((char *) buf + to_transfer); 497 } 498 499 return total; 500 } 501 502 503 504 /* Ensure that the buffer can provide the needed data. */ 505 506 offset_t client_seek(file_t *file, offset_t offset, int whence) 507 { 508 if (file == NULL) 509 return 0; 510 511 offset_t position, current = file_data_current_position(file), change; 512 513 switch (whence) 514 { 515 case SEEK_SET: 516 position = offset; 517 break; 518 519 case SEEK_CUR: 520 position = current + offset; 521 break; 522 523 case SEEK_END: 524 position = file->size + offset; 525 break; 526 527 default: 528 /* NOTE: Set errno to EINVAL. */ 529 return current; 530 } 531 532 /* Retain the current position if unchanged. */ 533 534 if (position == current) 535 return position; 536 537 /* Move forward in the file. */ 538 539 if (position > current) 540 { 541 change = position - current; 542 543 /* Move towards the end of available data. 544 Request new data if not enough is available. */ 545 546 if (change <= file_data_available(file)) 547 { 548 file->data_current += change; 549 return position; 550 } 551 } 552 553 /* Move backward in the file. */ 554 555 else 556 { 557 change = current - position; 558 559 /* Move towards the start of available data. 560 Request new data if moving beyond the start of the data. */ 561 562 if (change <= file->data_current) 563 { 564 file->data_current -= change; 565 return position; 566 } 567 } 568 569 /* Handle unwritten data and reset the buffer for reading. */ 570 571 if (_access(file, position)) 572 return current; 573 574 return position; 575 } 576 577 578 579 /* Set or unset blocking access for a file. */ 580 581 long client_set_blocking(file_t *file, notify_flags_t flags) 582 { 583 long err; 584 585 if (file->can_block == flags) 586 return L4_EOK; 587 588 /* Since blocking access is used with specific file notifications, the 589 per-task notifier is used. */ 590 591 file_notifier_t *notifier = client_notifier_task(); 592 593 if (flags) 594 err = client_subscribe(file, flags, notifier); 595 else 596 err = client_unsubscribe(file, notifier); 597 598 if (err) 599 return err; 600 601 file->can_block = flags; 602 return L4_EOK; 603 } 604 605 606 607 /* Subscribe from events concerning a file. */ 608 609 long client_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier) 610 { 611 if (file == NULL) 612 return -L4_EINVAL; 613 614 return file_notify_subscribe(file, flags, notifier); 615 } 616 617 618 619 /* Return the current position in the file. */ 620 621 long client_tell(file_t *file) 622 { 623 if (file == NULL) 624 return -L4_EINVAL; 625 626 return file_data_current_position(file); 627 } 628 629 630 631 /* Unsubscribe from events concerning a file. */ 632 633 long client_unsubscribe(file_t *file, file_notifier_t *notifier) 634 { 635 if (file == NULL) 636 return -L4_EINVAL; 637 638 return file_notify_unsubscribe(file, notifier); 639 } 640 641 642 643 /* Wait for events involving a specific file. */ 644 645 long client_wait_file(file_t *file, file_notifier_t *notifier) 646 { 647 if (file == NULL) 648 return -L4_EINVAL; 649 650 return file_notify_wait_file(file, notifier); 651 } 652 653 /* Wait for events concerning files, referencing a file object if an event is 654 delivered. */ 655 656 long client_wait_files(file_t **file, file_notifier_t *notifier) 657 { 658 return file_notify_wait_files(file, notifier); 659 } 660 661 662 663 /* Write to the filesystem object from the buffer provided. */ 664 665 offset_t client_write(file_t *file, const void *buf, offset_t count) 666 { 667 if (file == NULL) 668 return 0; 669 670 /* Map memory if none has been mapped so far. */ 671 672 if (_map_memory(file, count) == NULL) 673 return 0; 674 675 /* Attempt to ensure that the file can accept the amount of data to be 676 written. This may not resize to the needed amount if a file has a fixed 677 size, but data will still be written to any available space. */ 678 679 offset_t needed_size = file_data_current_position(file) + count; 680 681 if (file->object_flags & OBJECT_HAS_SIZE) 682 { 683 if (file->size < needed_size) 684 { 685 file_resize(file, needed_size); 686 687 if (file->size < needed_size) 688 count = file->size - file_data_current_position(file); 689 } 690 } 691 692 /* Space remaining in the descriptor buffer. */ 693 694 offset_t space = file_data_space(file); 695 offset_t to_transfer, total = 0; 696 697 while (count > 0) 698 { 699 /* If no space is available, try and send data, reset the buffer. */ 700 701 if (!space) 702 { 703 /* Flush any unwritten data and continue writing from the current data 704 position. */ 705 706 if (!_access_blocking(file, file_data_current_position(file), 0)) 707 break; 708 709 space = file_data_space(file); 710 } 711 712 /* Transfer data into the supplied buffer. */ 713 714 to_transfer = space <= count ? space : count; 715 716 file_data_write(file, (char *) buf, to_transfer); 717 718 /* Update counters. */ 719 720 space -= to_transfer; 721 722 count -= to_transfer; 723 total += to_transfer; 724 725 buf = ((char *) buf + to_transfer); 726 } 727 728 return total; 729 } 730 731 // vim: tabstop=2 expandtab shiftwidth=2