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 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 /* Obtain the current region of a pipe. */ 381 382 long client_current_region(file_t *file) 383 { 384 if (file == NULL) 385 return -L4_EINVAL; 386 387 return pipe_current(file); 388 } 389 390 391 392 /* Flush data explicitly to the filesystem object. */ 393 394 long client_flush(file_t *file) 395 { 396 if (file == NULL) 397 return -L4_EINVAL; 398 399 /* Flush and retain most buffer settings. */ 400 401 return file_flush(file); 402 } 403 404 405 406 /* Map a memory region to a file. */ 407 408 void *client_mmap(file_t *file, offset_t position, offset_t length) 409 { 410 if ((file == NULL) || (file_mmap(file, position, length))) 411 return NULL; 412 413 return file->memory; 414 } 415 416 417 418 /* Obtain the next region of a pipe. */ 419 420 long client_next_region(file_t *file) 421 { 422 if (file == NULL) 423 return -L4_EINVAL; 424 425 return pipe_next(file); 426 } 427 428 429 430 /* Close a notifier object. */ 431 432 void client_notifier_close(file_notifier_t *notifier) 433 { 434 file_notify_close(notifier); 435 } 436 437 /* Obtain a local notifier object. */ 438 439 file_notifier_t *client_notifier_local() 440 { 441 return file_notify_local(); 442 } 443 444 /* Obtain a task-wide notifier object. */ 445 446 file_notifier_t *client_notifier_task() 447 { 448 return file_notify_task(); 449 } 450 451 452 453 /* Read a directory entry. This must be freed by the caller after use. */ 454 455 struct dirent *client_readdir(file_t *file) 456 { 457 char buffer[DIRENT_CORE_SIZE]; 458 offset_t nread = client_read(file, buffer, DIRENT_CORE_SIZE); 459 460 /* Stop if no new structure can be successfully read. */ 461 462 if (nread != DIRENT_CORE_SIZE) 463 return NULL; 464 465 struct dirent *dirent = (struct dirent *) buffer; 466 offset_t remaining = dirent->d_reclen - DIRENT_CORE_SIZE; 467 468 /* Allocate a buffer for the complete structure. */ 469 470 char *entry = (char *) calloc(DIRENT_CORE_SIZE + remaining, sizeof(char)); 471 472 if (entry == NULL) 473 return NULL; 474 475 /* Copy the start of the entry into a new buffer. */ 476 477 memcpy(entry, buffer, DIRENT_CORE_SIZE); 478 479 /* Append to the entry buffer. */ 480 481 char *current = entry + DIRENT_CORE_SIZE; 482 483 nread = client_read(file, current, remaining); 484 485 /* Stop if no complete structure can be successfully read. */ 486 487 if (nread != remaining) 488 { 489 free(entry); 490 return NULL; 491 } 492 493 return (struct dirent *) entry; 494 } 495 496 497 498 /* Read from the filesystem object into the buffer provided. */ 499 500 offset_t client_read(file_t *file, void *buf, offset_t count) 501 { 502 if (file == NULL) 503 return 0; 504 505 /* Map memory if none has been mapped so far. */ 506 507 if (_map_memory(file, count) == NULL) 508 return 0; 509 510 /* Amount available in the descriptor buffer already. */ 511 512 offset_t available = file_data_available(file); 513 offset_t to_transfer, total = 0; 514 515 while (count > 0) 516 { 517 /* If there is no data, try and obtain more data. */ 518 519 if (!available) 520 { 521 /* Flush any unwritten data, preparing to read from the file position at 522 the end of the data, and returning if no new data is available. */ 523 524 if (!_access_blocking(file, file_data_end_position(file), 1)) 525 break; 526 527 available = file_data_available(file); 528 529 if (!available) 530 break; 531 } 532 533 /* Transfer data into the supplied buffer. */ 534 535 to_transfer = available <= count ? available : count; 536 537 file_data_read(file, (char *) buf, to_transfer); 538 539 /* Update counters. */ 540 541 available -= to_transfer; 542 543 count -= to_transfer; 544 total += to_transfer; 545 546 buf = ((char *) buf + to_transfer); 547 } 548 549 return total; 550 } 551 552 553 554 /* Ensure that the buffer can provide the needed data. */ 555 556 offset_t client_seek(file_t *file, offset_t offset, int whence) 557 { 558 if (file == NULL) 559 return 0; 560 561 offset_t position, current = file_data_current_position(file), change; 562 563 switch (whence) 564 { 565 case SEEK_SET: 566 position = offset; 567 break; 568 569 case SEEK_CUR: 570 position = current + offset; 571 break; 572 573 case SEEK_END: 574 position = file->size + offset; 575 break; 576 577 default: 578 /* NOTE: Set errno to EINVAL. */ 579 return current; 580 } 581 582 /* Retain the current position if unchanged. */ 583 584 if (position == current) 585 return position; 586 587 /* Move forward in the file. */ 588 589 if (position > current) 590 { 591 change = position - current; 592 593 /* Move towards the end of available data. 594 Request new data if not enough is available. */ 595 596 if (change <= file_data_available(file)) 597 { 598 file->data_current += change; 599 return position; 600 } 601 } 602 603 /* Move backward in the file. */ 604 605 else 606 { 607 change = current - position; 608 609 /* Move towards the start of available data. 610 Request new data if moving beyond the start of the data. */ 611 612 if (change <= file->data_current) 613 { 614 file->data_current -= change; 615 return position; 616 } 617 } 618 619 /* Handle unwritten data and reset the buffer for reading. */ 620 621 if (_access(file, position)) 622 return current; 623 624 return position; 625 } 626 627 628 629 /* Set or unset blocking access for a file. */ 630 631 long client_set_blocking(file_t *file, notify_flags_t flags) 632 { 633 long err; 634 635 if (file->can_block == flags) 636 return L4_EOK; 637 638 /* Since blocking access is used with specific file notifications, the 639 per-task notifier is used. */ 640 641 file_notifier_t *notifier = client_notifier_task(); 642 643 if (flags) 644 err = client_subscribe(file, flags, notifier); 645 else 646 err = client_unsubscribe(file, notifier); 647 648 if (err) 649 return err; 650 651 file->can_block = flags; 652 return L4_EOK; 653 } 654 655 656 657 /* Subscribe from events concerning a file. */ 658 659 long client_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier) 660 { 661 if (file == NULL) 662 return -L4_EINVAL; 663 664 return file_notify_subscribe(file, flags, notifier); 665 } 666 667 668 669 /* Return the current position in the file. */ 670 671 long client_tell(file_t *file) 672 { 673 if (file == NULL) 674 return -L4_EINVAL; 675 676 return file_data_current_position(file); 677 } 678 679 680 681 /* Unsubscribe from events concerning a file. */ 682 683 long client_unsubscribe(file_t *file, file_notifier_t *notifier) 684 { 685 if (file == NULL) 686 return -L4_EINVAL; 687 688 return file_notify_unsubscribe(file, notifier); 689 } 690 691 692 693 /* Wait for events involving a specific file. */ 694 695 long client_wait_file(file_t *file, file_notifier_t *notifier) 696 { 697 if (file == NULL) 698 return -L4_EINVAL; 699 700 return file_notify_wait_file(file, notifier); 701 } 702 703 /* Wait for events concerning files, referencing a file object if an event is 704 delivered. */ 705 706 long client_wait_files(file_t **file, file_notifier_t *notifier) 707 { 708 return file_notify_wait_files(file, notifier); 709 } 710 711 712 713 /* Write to the filesystem object from the buffer provided. */ 714 715 offset_t client_write(file_t *file, const void *buf, offset_t count) 716 { 717 if (file == NULL) 718 return 0; 719 720 /* Map memory if none has been mapped so far. */ 721 722 if (_map_memory(file, count) == NULL) 723 return 0; 724 725 /* Attempt to ensure that the file can accept the amount of data to be 726 written. This may not resize to the needed amount if a file has a fixed 727 size, but data will still be written to any available space. */ 728 729 offset_t needed_size = file_data_current_position(file) + count; 730 731 if (file->object_flags & OBJECT_HAS_SIZE) 732 { 733 if (file->size < needed_size) 734 { 735 file_resize(file, needed_size); 736 737 if (file->size < needed_size) 738 count = file->size - file_data_current_position(file); 739 } 740 } 741 742 /* Space remaining in the descriptor buffer. */ 743 744 offset_t space = file_data_space(file); 745 offset_t to_transfer, total = 0; 746 747 while (count > 0) 748 { 749 /* If no space is available, try and send data, reset the buffer. */ 750 751 if (!space) 752 { 753 /* Flush any unwritten data and continue writing from the current data 754 position. */ 755 756 if (!_access_blocking(file, file_data_current_position(file), 0)) 757 break; 758 759 space = file_data_space(file); 760 } 761 762 /* Transfer data into the supplied buffer. */ 763 764 to_transfer = space <= count ? space : count; 765 766 file_data_write(file, (char *) buf, to_transfer); 767 768 /* Update counters. */ 769 770 space -= to_transfer; 771 772 count -= to_transfer; 773 total += to_transfer; 774 775 buf = ((char *) buf + to_transfer); 776 } 777 778 return total; 779 } 780 781 // vim: tabstop=2 expandtab shiftwidth=2