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 /* Obtain the current region of a pipe. */ 363 364 long client_current_region(file_t *file) 365 { 366 if (file == NULL) 367 return -L4_EINVAL; 368 369 return pipe_current(file); 370 } 371 372 373 374 /* Flush data explicitly to the filesystem object. */ 375 376 long client_flush(file_t *file) 377 { 378 if (file == NULL) 379 return -L4_EINVAL; 380 381 /* Flush and retain most buffer settings. */ 382 383 return file_flush(file); 384 } 385 386 387 388 /* Map a memory region to a file. */ 389 390 void *client_mmap(file_t *file, offset_t position, offset_t length) 391 { 392 if ((file == NULL) || (file_mmap(file, position, length))) 393 return NULL; 394 395 return file->memory; 396 } 397 398 399 400 /* Obtain the next region of a pipe. */ 401 402 long client_next_region(file_t *file) 403 { 404 if (file == NULL) 405 return -L4_EINVAL; 406 407 return pipe_next(file); 408 } 409 410 411 412 /* Close a notifier object. */ 413 414 void client_notifier_close(file_notifier_t *notifier) 415 { 416 file_notify_close(notifier); 417 } 418 419 /* Obtain a local notifier object. */ 420 421 file_notifier_t *client_notifier_local() 422 { 423 return file_notify_local(); 424 } 425 426 /* Obtain a task-wide notifier object. */ 427 428 file_notifier_t *client_notifier_task() 429 { 430 return file_notify_task(); 431 } 432 433 434 435 /* Read a directory entry. This must be freed by the caller after use. */ 436 437 struct dirent *client_readdir(file_t *file) 438 { 439 char buffer[DIRENT_CORE_SIZE]; 440 offset_t nread = client_read(file, buffer, DIRENT_CORE_SIZE); 441 442 /* Stop if no new structure can be successfully read. */ 443 444 if (nread != DIRENT_CORE_SIZE) 445 return NULL; 446 447 struct dirent *dirent = (struct dirent *) buffer; 448 offset_t remaining = dirent->d_reclen - DIRENT_CORE_SIZE; 449 450 /* Allocate a buffer for the complete structure. */ 451 452 char *entry = (char *) calloc(DIRENT_CORE_SIZE + remaining, sizeof(char)); 453 454 if (entry == NULL) 455 return NULL; 456 457 /* Copy the start of the entry into a new buffer. */ 458 459 memcpy(entry, buffer, DIRENT_CORE_SIZE); 460 461 /* Append to the entry buffer. */ 462 463 char *current = entry + DIRENT_CORE_SIZE; 464 465 nread = client_read(file, current, remaining); 466 467 /* Stop if no complete structure can be successfully read. */ 468 469 if (nread != remaining) 470 { 471 free(entry); 472 return NULL; 473 } 474 475 return (struct dirent *) entry; 476 } 477 478 479 480 /* Read from the filesystem object into the buffer provided. */ 481 482 offset_t client_read(file_t *file, void *buf, offset_t count) 483 { 484 if (file == NULL) 485 return 0; 486 487 /* Map memory if none has been mapped so far. */ 488 489 if (_map_memory(file, count) == NULL) 490 return 0; 491 492 /* Amount available in the descriptor buffer already. */ 493 494 offset_t available = file_data_available(file); 495 offset_t to_transfer, total = 0; 496 497 while (count > 0) 498 { 499 /* If there is no data, try and obtain more data. */ 500 501 if (!available) 502 { 503 /* Flush any unwritten data, preparing to read from the file position at 504 the end of the data, and returning if no new data is available. */ 505 506 if (!_access_blocking(file, file_data_end_position(file), 1)) 507 break; 508 509 available = file_data_available(file); 510 511 if (!available) 512 break; 513 } 514 515 /* Transfer data into the supplied buffer. */ 516 517 to_transfer = available <= count ? available : count; 518 519 file_data_read(file, (char *) buf, to_transfer); 520 521 /* Update counters. */ 522 523 available -= to_transfer; 524 525 count -= to_transfer; 526 total += to_transfer; 527 528 buf = ((char *) buf + to_transfer); 529 } 530 531 return total; 532 } 533 534 535 536 /* Ensure that the buffer can provide the needed data. */ 537 538 offset_t client_seek(file_t *file, offset_t offset, int whence) 539 { 540 if (file == NULL) 541 return 0; 542 543 offset_t position, current = file_data_current_position(file), change; 544 545 switch (whence) 546 { 547 case SEEK_SET: 548 position = offset; 549 break; 550 551 case SEEK_CUR: 552 position = current + offset; 553 break; 554 555 case SEEK_END: 556 position = file->size + offset; 557 break; 558 559 default: 560 /* NOTE: Set errno to EINVAL. */ 561 return current; 562 } 563 564 /* Retain the current position if unchanged. */ 565 566 if (position == current) 567 return position; 568 569 /* Move forward in the file. */ 570 571 if (position > current) 572 { 573 change = position - current; 574 575 /* Move towards the end of available data. 576 Request new data if not enough is available. */ 577 578 if (change <= file_data_available(file)) 579 { 580 file->data_current += change; 581 return position; 582 } 583 } 584 585 /* Move backward in the file. */ 586 587 else 588 { 589 change = current - position; 590 591 /* Move towards the start of available data. 592 Request new data if moving beyond the start of the data. */ 593 594 if (change <= file->data_current) 595 { 596 file->data_current -= change; 597 return position; 598 } 599 } 600 601 /* Handle unwritten data and reset the buffer for reading. */ 602 603 if (_access(file, position)) 604 return current; 605 606 return position; 607 } 608 609 610 611 /* Set or unset blocking access for a file. */ 612 613 long client_set_blocking(file_t *file, notify_flags_t flags) 614 { 615 long err; 616 617 if (file->can_block == flags) 618 return L4_EOK; 619 620 /* Since blocking access is used with specific file notifications, the 621 per-task notifier is used. */ 622 623 file_notifier_t *notifier = client_notifier_task(); 624 625 if (flags) 626 err = client_subscribe(file, flags, notifier); 627 else 628 err = client_unsubscribe(file, notifier); 629 630 if (err) 631 return err; 632 633 file->can_block = flags; 634 return L4_EOK; 635 } 636 637 638 639 /* Subscribe from events concerning a file. */ 640 641 long client_subscribe(file_t *file, notify_flags_t flags, file_notifier_t *notifier) 642 { 643 if (file == NULL) 644 return -L4_EINVAL; 645 646 return file_notify_subscribe(file, flags, notifier); 647 } 648 649 650 651 /* Return the current position in the file. */ 652 653 long client_tell(file_t *file) 654 { 655 if (file == NULL) 656 return -L4_EINVAL; 657 658 return file_data_current_position(file); 659 } 660 661 662 663 /* Unsubscribe from events concerning a file. */ 664 665 long client_unsubscribe(file_t *file, file_notifier_t *notifier) 666 { 667 if (file == NULL) 668 return -L4_EINVAL; 669 670 return file_notify_unsubscribe(file, notifier); 671 } 672 673 674 675 /* Wait for events involving a specific file. */ 676 677 long client_wait_file(file_t *file, file_notifier_t *notifier) 678 { 679 if (file == NULL) 680 return -L4_EINVAL; 681 682 return file_notify_wait_file(file, notifier); 683 } 684 685 /* Wait for events concerning files, referencing a file object if an event is 686 delivered. */ 687 688 long client_wait_files(file_t **file, file_notifier_t *notifier) 689 { 690 return file_notify_wait_files(file, notifier); 691 } 692 693 694 695 /* Write to the filesystem object from the buffer provided. */ 696 697 offset_t client_write(file_t *file, const void *buf, offset_t count) 698 { 699 if (file == NULL) 700 return 0; 701 702 /* Map memory if none has been mapped so far. */ 703 704 if (_map_memory(file, count) == NULL) 705 return 0; 706 707 /* Attempt to ensure that the file can accept the amount of data to be 708 written. This may not resize to the needed amount if a file has a fixed 709 size, but data will still be written to any available space. */ 710 711 offset_t needed_size = file_data_current_position(file) + count; 712 713 if (file->object_flags & OBJECT_HAS_SIZE) 714 { 715 if (file->size < needed_size) 716 { 717 file_resize(file, needed_size); 718 719 if (file->size < needed_size) 720 count = file->size - file_data_current_position(file); 721 } 722 } 723 724 /* Space remaining in the descriptor buffer. */ 725 726 offset_t space = file_data_space(file); 727 offset_t to_transfer, total = 0; 728 729 while (count > 0) 730 { 731 /* If no space is available, try and send data, reset the buffer. */ 732 733 if (!space) 734 { 735 /* Flush any unwritten data and continue writing from the current data 736 position. */ 737 738 if (!_access_blocking(file, file_data_current_position(file), 0)) 739 break; 740 741 space = file_data_space(file); 742 } 743 744 /* Transfer data into the supplied buffer. */ 745 746 to_transfer = space <= count ? space : count; 747 748 file_data_write(file, (char *) buf, to_transfer); 749 750 /* Update counters. */ 751 752 space -= to_transfer; 753 754 count -= to_transfer; 755 total += to_transfer; 756 757 buf = ((char *) buf + to_transfer); 758 } 759 760 return total; 761 } 762 763 // vim: tabstop=2 expandtab shiftwidth=2