1 /* 2 * Filesystem client functions. 3 * 4 * Copyright (C) 2018, 2019, 2020, 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 <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 named directory. */ 251 252 file_t *client_opendir(const char *name) 253 { 254 l4_cap_idx_t server = l4re_env_get_cap("server"); 255 256 return client_opendir_using(name, server); 257 } 258 259 /* Open a directory listing stream via the given named directory and a named 260 capability. */ 261 262 file_t *client_opendir_using(const char *name, l4_cap_idx_t server) 263 { 264 file_t *file = client_open_using(name, O_DIRECTORY, server); 265 266 if (file == NULL) 267 return NULL; 268 269 file_t *reader = client_opendir_at(file); 270 271 if (reader == NULL) 272 return NULL; 273 274 /* Release the directory and return the reader. */ 275 276 client_close(file); 277 return reader; 278 } 279 280 281 282 /* Open a directory listing stream via the given directory. */ 283 284 file_t *client_opendir_at(file_t *file) 285 { 286 if (file == NULL) 287 return NULL; 288 289 file_t *reader = (file_t *) malloc(sizeof(file_t)); 290 291 if (reader == NULL) 292 return NULL; 293 294 long err = directory_opendir(file, reader); 295 296 if (err) 297 return NULL; 298 299 /* Set blocking read mode to be able to conveniently read directory entries 300 from the stream. */ 301 302 if (client_set_blocking(reader, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED)) 303 { 304 client_close(reader); 305 return NULL; 306 } 307 308 return reader; 309 } 310 311 312 313 /* Open a pipe object. */ 314 315 long client_pipe(file_t **reader, file_t **writer, flags_t flags) 316 { 317 l4_cap_idx_t server = l4re_env_get_cap("pipes"); 318 319 return client_pipe_using(reader, writer, flags, server); 320 } 321 322 long client_pipe_using(file_t **reader, file_t **writer, flags_t flags, l4_cap_idx_t server) 323 { 324 if (l4_is_invalid_cap(server)) 325 return -L4_EINVAL; 326 327 *reader = (file_t *) malloc(sizeof(file_t)); 328 329 if (*reader == NULL) 330 return -L4_ENOMEM; 331 332 *writer = (file_t *) malloc(sizeof(file_t)); 333 334 if (*writer == NULL) 335 { 336 free(*reader); 337 return -L4_ENOMEM; 338 } 339 340 long err = pipe_open(DEFAULT_PIPE_SIZE, *reader, *writer, server); 341 342 /* Set blocking if successful and non-blocking is not indicated. */ 343 344 if (!err && !(flags & O_NONBLOCK)) 345 { 346 err = client_set_blocking(*reader, NOTIFY_CONTENT_AVAILABLE | NOTIFY_PEER_CLOSED); 347 if (!err) 348 err = client_set_blocking(*writer, NOTIFY_SPACE_AVAILABLE | NOTIFY_PEER_CLOSED); 349 } 350 351 if (err) 352 { 353 free(*reader); 354 free(*writer); 355 } 356 357 return err; 358 } 359 360 361 362 /* Remove a file from the filesystem. */ 363 364 long client_remove(const char *name) 365 { 366 l4_cap_idx_t server = l4re_env_get_cap("server"); 367 368 return client_remove_using(name, server); 369 } 370 371 /* Remove a file from the filesystem via a named capability. */ 372 373 long client_remove_using(const char *name, l4_cap_idx_t server) 374 { 375 return file_remove(name, server); 376 } 377 378 379 380 /* Rename a file in the filesystem. */ 381 382 long client_rename(const char *source, const char *target) 383 { 384 l4_cap_idx_t server = l4re_env_get_cap("server"); 385 386 return client_rename_using(source, target, server); 387 } 388 389 /* Rename a file in the filesystem via a named capability. */ 390 391 long client_rename_using(const char *source, const char *target, l4_cap_idx_t server) 392 { 393 return file_rename(source, target, server); 394 } 395 396 397 398 /* Obtain the current region of a pipe. */ 399 400 long client_current_region(file_t *file) 401 { 402 if (file == NULL) 403 return -L4_EINVAL; 404 405 return pipe_current(file); 406 } 407 408 409 410 /* Flush data explicitly to the filesystem object. */ 411 412 long client_flush(file_t *file) 413 { 414 if (file == NULL) 415 return -L4_EINVAL; 416 417 /* Flush and retain most buffer settings. */ 418 419 return file_flush(file); 420 } 421 422 423 424 /* Map a memory region to a file. */ 425 426 void *client_mmap(file_t *file, offset_t position, offset_t length) 427 { 428 if ((file == NULL) || (file_mmap(file, position, length))) 429 return NULL; 430 431 return file->memory; 432 } 433 434 435 436 /* Obtain the next region of a pipe. */ 437 438 long client_next_region(file_t *file) 439 { 440 if (file == NULL) 441 return -L4_EINVAL; 442 443 return pipe_next(file); 444 } 445 446 447 448 /* Close a notifier object. */ 449 450 void client_notifier_close(file_notifier_t *notifier) 451 { 452 file_notify_close(notifier); 453 } 454 455 /* Obtain a local notifier object. */ 456 457 file_notifier_t *client_notifier_local() 458 { 459 return file_notify_local(); 460 } 461 462 /* Obtain a task-wide notifier object. */ 463 464 file_notifier_t *client_notifier_task() 465 { 466 return file_notify_task(); 467 } 468 469 470 471 /* Read a directory entry. This must be freed by the caller after use. */ 472 473 struct dirent *client_readdir(file_t *file) 474 { 475 char buffer[DIRENT_CORE_SIZE]; 476 offset_t nread = client_read(file, buffer, DIRENT_CORE_SIZE); 477 478 /* Stop if no new structure can be successfully read. */ 479 480 if (nread != DIRENT_CORE_SIZE) 481 return NULL; 482 483 struct dirent *dirent = (struct dirent *) buffer; 484 offset_t remaining = dirent->d_reclen - DIRENT_CORE_SIZE; 485 486 /* Allocate a buffer for the complete structure. */ 487 488 char *entry = (char *) calloc(DIRENT_CORE_SIZE + remaining, sizeof(char)); 489 490 if (entry == NULL) 491 return NULL; 492 493 /* Copy the start of the entry into a new buffer. */ 494 495 memcpy(entry, buffer, DIRENT_CORE_SIZE); 496 497 /* Append to the entry buffer. */ 498 499 char *current = entry + DIRENT_CORE_SIZE; 500 501 nread = client_read(file, current, remaining); 502 503 /* Stop if no complete structure can be successfully read. */ 504 505 if (nread != remaining) 506 { 507 free(entry); 508 return NULL; 509 } 510 511 return (struct dirent *) entry; 512 } 513 514 515 516 /* Read from the filesystem object into the buffer provided. */ 517 518 offset_t client_read(file_t *file, void *buf, offset_t count) 519 { 520 if (file == NULL) 521 return 0; 522 523 /* Map memory if none has been mapped so far. */ 524 525 if (_map_memory(file, count) == NULL) 526 return 0; 527 528 /* Amount available in the descriptor buffer already. */ 529 530 offset_t available = file_data_available(file); 531 offset_t to_transfer, total = 0; 532 533 while (count > 0) 534 { 535 /* If there is no data, try and obtain more data. */ 536 537 if (!available) 538 { 539 /* Flush any unwritten data, preparing to read from the file position at 540 the end of the data, and returning if no new data is available. */ 541 542 if (!_access_blocking(file, file_data_end_position(file), 1)) 543 break; 544 545 available = file_data_available(file); 546 547 if (!available) 548 break; 549 } 550 551 /* Transfer data into the supplied buffer. */ 552 553 to_transfer = available <= count ? available : count; 554 555 file_data_read(file, (char *) buf, to_transfer); 556 557 /* Update counters. */ 558 559 available -= to_transfer; 560 561 count -= to_transfer; 562 total += to_transfer; 563 564 buf = ((char *) buf + to_transfer); 565 } 566 567 return total; 568 } 569 570 571 572 /* Ensure that the buffer can provide the needed data. */ 573 574 offset_t client_seek(file_t *file, offset_t offset, int whence) 575 { 576 if (file == NULL) 577 return 0; 578 579 offset_t position, current = file_data_current_position(file), change; 580 581 switch (whence) 582 { 583 case SEEK_SET: 584 position = offset; 585 break; 586 587 case SEEK_CUR: 588 position = current + offset; 589 break; 590 591 case SEEK_END: 592 position = file->size + offset; 593 break; 594 595 default: 596 /* NOTE: Set errno to EINVAL. */ 597 return current; 598 } 599 600 /* Retain the current position if unchanged. */ 601 602 if (position == current) 603 return position; 604 605 /* Move forward in the file. */ 606 607 if (position > current) 608 { 609 change = position - current; 610 611 /* Move towards the end of available data. 612 Request new data if not enough is available. */ 613 614 if (change <= file_data_available(file)) 615 { 616 file->data_current += change; 617 return position; 618 } 619 } 620 621 /* Move backward in the file. */ 622 623 else 624 { 625 change = current - position; 626 627 /* Move towards the start of available data. 628 Request new data if moving beyond the start of the data. */ 629 630 if (change <= file->data_current) 631 { 632 file->data_current -= change; 633 return position; 634 } 635 } 636 637 /* Handle unwritten data and reset the buffer for reading. */ 638 639 if (_access(file, position)) 640 return current; 641 642 return position; 643 } 644 645 646 647 /* Set or unset blocking access for a file. */ 648 649 long client_set_blocking(file_t *file, notify_flags_t flags) 650 { 651 long err; 652 653 if (file->can_block == flags) 654 return L4_EOK; 655 656 /* Since blocking access is used with specific file notifications, the 657 per-task notifier is used. */ 658 659 file_notifier_t *notifier = client_notifier_task(); 660 661 if (flags) 662 err = client_subscribe(file, flags, notifier); 663 else 664 err = client_unsubscribe(file, notifier); 665 666 if (err) 667 return err; 668 669 file->can_block = flags; 670 return L4_EOK; 671 } 672 673 674 675 /* Subscribe from events concerning a file. */ 676 677 long client_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier) 678 { 679 if (file == NULL) 680 return -L4_EINVAL; 681 682 return file_notify_subscribe(file, flags, notifier); 683 } 684 685 686 687 /* Return the current position in the file. */ 688 689 long client_tell(file_t *file) 690 { 691 if (file == NULL) 692 return -L4_EINVAL; 693 694 return file_data_current_position(file); 695 } 696 697 698 699 /* Unsubscribe from events concerning a file. */ 700 701 long client_unsubscribe(file_t *file, file_notifier_t *notifier) 702 { 703 if (file == NULL) 704 return -L4_EINVAL; 705 706 return file_notify_unsubscribe(file, notifier); 707 } 708 709 710 711 /* Wait for events involving a specific file. */ 712 713 long client_wait_file(file_t *file, file_notifier_t *notifier) 714 { 715 if (file == NULL) 716 return -L4_EINVAL; 717 718 return file_notify_wait_file(file, notifier); 719 } 720 721 /* Wait for events concerning files, referencing a file object if an event is 722 delivered. */ 723 724 long client_wait_files(file_t **file, file_notifier_t *notifier) 725 { 726 return file_notify_wait_files(file, notifier); 727 } 728 729 730 731 /* Write to the filesystem object from the buffer provided. */ 732 733 offset_t client_write(file_t *file, const void *buf, offset_t count) 734 { 735 if (file == NULL) 736 return 0; 737 738 /* Map memory if none has been mapped so far. */ 739 740 if (_map_memory(file, count) == NULL) 741 return 0; 742 743 /* Attempt to ensure that the file can accept the amount of data to be 744 written. This may not resize to the needed amount if a file has a fixed 745 size, but data will still be written to any available space. */ 746 747 offset_t needed_size = file_data_current_position(file) + count; 748 749 if (file->object_flags & OBJECT_HAS_SIZE) 750 { 751 if (file->size < needed_size) 752 { 753 file_resize(file, needed_size); 754 755 if (file->size < needed_size) 756 count = file->size - file_data_current_position(file); 757 } 758 } 759 760 /* Space remaining in the descriptor buffer. */ 761 762 offset_t space = file_data_space(file); 763 offset_t to_transfer, total = 0; 764 765 while (count > 0) 766 { 767 /* If no space is available, try and send data, reset the buffer. */ 768 769 if (!space) 770 { 771 /* Flush any unwritten data and continue writing from the current data 772 position. */ 773 774 if (!_access_blocking(file, file_data_current_position(file), 0)) 775 break; 776 777 space = file_data_space(file); 778 } 779 780 /* Transfer data into the supplied buffer. */ 781 782 to_transfer = space <= count ? space : count; 783 784 file_data_write(file, (char *) buf, to_transfer); 785 786 /* Update counters. */ 787 788 space -= to_transfer; 789 790 count -= to_transfer; 791 total += to_transfer; 792 793 buf = ((char *) buf + to_transfer); 794 } 795 796 return total; 797 } 798 799 // vim: tabstop=2 expandtab shiftwidth=2