1 /* 2 * Copyright (C) 1984-2012 Mark Nudelman 3 * Modified for use with illumos by Garrett D'Amore. 4 * Copyright 2014 Garrett D'Amore <garrett@damore.org> 5 * 6 * You may distribute under the terms of either the GNU General Public 7 * License or the Less License, as specified in the README file. 8 * 9 * For more information, see the README file. 10 */ 11 12 /* 13 * Low level character input from the input file. 14 * We use these special purpose routines which optimize moving 15 * both forward and backward from the current read pointer. 16 */ 17 18 #include <sys/stat.h> 19 20 #include "less.h" 21 22 extern dev_t curr_dev; 23 extern ino_t curr_ino; 24 extern int less_is_more; 25 26 typedef off_t BLOCKNUM; 27 28 int ignore_eoi; 29 30 /* 31 * Pool of buffers holding the most recently used blocks of the input file. 32 * The buffer pool is kept as a doubly-linked circular list, 33 * in order from most- to least-recently used. 34 * The circular list is anchored by the file state "thisfile". 35 */ 36 struct bufnode { 37 struct bufnode *next, *prev; 38 struct bufnode *hnext, *hprev; 39 }; 40 41 #define LBUFSIZE 8192 42 struct buf { 43 struct bufnode node; 44 BLOCKNUM block; 45 unsigned int datasize; 46 unsigned char data[LBUFSIZE]; 47 }; 48 #define bufnode_buf(bn) ((struct buf *)bn) 49 50 /* 51 * The file state is maintained in a filestate structure. 52 * A pointer to the filestate is kept in the ifile structure. 53 */ 54 #define BUFHASH_SIZE 64 55 struct filestate { 56 struct bufnode buflist; 57 struct bufnode hashtbl[BUFHASH_SIZE]; 58 int file; 59 int flags; 60 off_t fpos; 61 int nbufs; 62 BLOCKNUM block; 63 unsigned int offset; 64 off_t fsize; 65 }; 66 67 #define ch_bufhead thisfile->buflist.next 68 #define ch_buftail thisfile->buflist.prev 69 #define ch_nbufs thisfile->nbufs 70 #define ch_block thisfile->block 71 #define ch_offset thisfile->offset 72 #define ch_fpos thisfile->fpos 73 #define ch_fsize thisfile->fsize 74 #define ch_flags thisfile->flags 75 #define ch_file thisfile->file 76 77 #define END_OF_CHAIN (&thisfile->buflist) 78 #define END_OF_HCHAIN(h) (&thisfile->hashtbl[h]) 79 #define BUFHASH(blk) ((blk) & (BUFHASH_SIZE-1)) 80 81 /* 82 * Macros to manipulate the list of buffers in thisfile->buflist. 83 */ 84 #define FOR_BUFS(bn) \ 85 for ((bn) = ch_bufhead; (bn) != END_OF_CHAIN; (bn) = (bn)->next) 86 87 #define BUF_RM(bn) \ 88 (bn)->next->prev = (bn)->prev; \ 89 (bn)->prev->next = (bn)->next; 90 91 #define BUF_INS_HEAD(bn) \ 92 (bn)->next = ch_bufhead; \ 93 (bn)->prev = END_OF_CHAIN; \ 94 ch_bufhead->prev = (bn); \ 95 ch_bufhead = (bn); 96 97 #define BUF_INS_TAIL(bn) \ 98 (bn)->next = END_OF_CHAIN; \ 99 (bn)->prev = ch_buftail; \ 100 ch_buftail->next = (bn); \ 101 ch_buftail = (bn); 102 103 /* 104 * Macros to manipulate the list of buffers in thisfile->hashtbl[n]. 105 */ 106 #define FOR_BUFS_IN_CHAIN(h, bn) \ 107 for ((bn) = thisfile->hashtbl[h].hnext; \ 108 (bn) != END_OF_HCHAIN(h); (bn) = (bn)->hnext) 109 110 #define BUF_HASH_RM(bn) \ 111 (bn)->hnext->hprev = (bn)->hprev; \ 112 (bn)->hprev->hnext = (bn)->hnext; 113 114 #define BUF_HASH_INS(bn, h) \ 115 (bn)->hnext = thisfile->hashtbl[h].hnext; \ 116 (bn)->hprev = END_OF_HCHAIN(h); \ 117 thisfile->hashtbl[h].hnext->hprev = (bn); \ 118 thisfile->hashtbl[h].hnext = (bn); 119 120 static struct filestate *thisfile; 121 static int ch_ungotchar = -1; 122 static int maxbufs = -1; 123 124 extern int autobuf; 125 extern int secure; 126 extern int screen_trashed; 127 extern int follow_mode; 128 extern IFILE curr_ifile; 129 extern int logfile; 130 extern char *namelogfile; 131 132 static int ch_addbuf(void); 133 134 135 /* 136 * Get the character pointed to by the read pointer. 137 */ 138 int 139 ch_get(void) 140 { 141 struct buf *bp; 142 struct bufnode *bn; 143 int n; 144 int slept; 145 int h; 146 off_t pos; 147 off_t len; 148 149 if (thisfile == NULL) 150 return (EOI); 151 152 /* 153 * Quick check for the common case where 154 * the desired char is in the head buffer. 155 */ 156 if (ch_bufhead != END_OF_CHAIN) { 157 bp = bufnode_buf(ch_bufhead); 158 if (ch_block == bp->block && ch_offset < bp->datasize) 159 return (bp->data[ch_offset]); 160 } 161 162 slept = FALSE; 163 164 /* 165 * Look for a buffer holding the desired block. 166 */ 167 h = BUFHASH(ch_block); 168 FOR_BUFS_IN_CHAIN(h, bn) { 169 bp = bufnode_buf(bn); 170 if (bp->block == ch_block) { 171 if (ch_offset >= bp->datasize) 172 /* 173 * Need more data in this buffer. 174 */ 175 break; 176 goto found; 177 } 178 } 179 if (bn == END_OF_HCHAIN(h)) { 180 /* 181 * Block is not in a buffer. 182 * Take the least recently used buffer 183 * and read the desired block into it. 184 * If the LRU buffer has data in it, 185 * then maybe allocate a new buffer. 186 */ 187 if (ch_buftail == END_OF_CHAIN || 188 bufnode_buf(ch_buftail)->block != -1) { 189 /* 190 * There is no empty buffer to use. 191 * Allocate a new buffer if: 192 * 1. We can't seek on this file and -b is not in 193 * effect; or 194 * 2. We haven't allocated the max buffers for this 195 * file yet. 196 */ 197 if ((autobuf && !(ch_flags & CH_CANSEEK)) || 198 (maxbufs < 0 || ch_nbufs < maxbufs)) 199 if (ch_addbuf()) 200 /* 201 * Allocation failed: turn off autobuf. 202 */ 203 autobuf = OPT_OFF; 204 } 205 bn = ch_buftail; 206 bp = bufnode_buf(bn); 207 BUF_HASH_RM(bn); /* Remove from old hash chain. */ 208 bp->block = ch_block; 209 bp->datasize = 0; 210 BUF_HASH_INS(bn, h); /* Insert into new hash chain. */ 211 } 212 213 read_more: 214 pos = (ch_block * LBUFSIZE) + bp->datasize; 215 if ((len = ch_length()) != -1 && pos >= len) 216 /* 217 * At end of file. 218 */ 219 return (EOI); 220 221 if (pos != ch_fpos) { 222 /* 223 * Not at the correct position: must seek. 224 * If input is a pipe, we're in trouble (can't seek on a pipe). 225 * Some data has been lost: just return "?". 226 */ 227 if (!(ch_flags & CH_CANSEEK)) 228 return ('?'); 229 if (lseek(ch_file, (off_t)pos, SEEK_SET) == (off_t)-1) { 230 error("seek error", NULL); 231 clear_eol(); 232 return (EOI); 233 } 234 ch_fpos = pos; 235 } 236 237 /* 238 * Read the block. 239 * If we read less than a full block, that's ok. 240 * We use partial block and pick up the rest next time. 241 */ 242 if (ch_ungotchar != -1) { 243 bp->data[bp->datasize] = (unsigned char)ch_ungotchar; 244 n = 1; 245 ch_ungotchar = -1; 246 } else { 247 n = iread(ch_file, &bp->data[bp->datasize], 248 (unsigned int)(LBUFSIZE - bp->datasize)); 249 } 250 251 if (n == READ_INTR) 252 return (EOI); 253 if (n < 0) { 254 error("read error", NULL); 255 clear_eol(); 256 n = 0; 257 } 258 259 /* 260 * If we have a log file, write the new data to it. 261 */ 262 if (!secure && logfile >= 0 && n > 0) 263 (void) write(logfile, (char *)&bp->data[bp->datasize], n); 264 265 ch_fpos += n; 266 bp->datasize += n; 267 268 /* 269 * If we have read to end of file, set ch_fsize to indicate 270 * the position of the end of file. 271 */ 272 if (n == 0) { 273 ch_fsize = pos; 274 if (ignore_eoi) { 275 /* 276 * We are ignoring EOF. 277 * Wait a while, then try again. 278 */ 279 if (!slept) { 280 PARG parg; 281 parg.p_string = wait_message(); 282 ierror("%s", &parg); 283 } 284 sleep(1); 285 slept = TRUE; 286 287 if (follow_mode == FOLLOW_NAME) { 288 /* 289 * See whether the file's i-number has changed. 290 * If so, force the file to be closed and 291 * reopened. 292 */ 293 struct stat st; 294 int r = stat(get_filename(curr_ifile), &st); 295 if (r == 0 && (st.st_ino != curr_ino || 296 st.st_dev != curr_dev)) { 297 /* 298 * screen_trashed=2 causes 299 * make_display to reopen the file. 300 */ 301 screen_trashed = 2; 302 return (EOI); 303 } 304 } 305 } 306 if (any_sigs()) 307 return (EOI); 308 } 309 310 found: 311 if (ch_bufhead != bn) { 312 /* 313 * Move the buffer to the head of the buffer chain. 314 * This orders the buffer chain, most- to least-recently used. 315 */ 316 BUF_RM(bn); 317 BUF_INS_HEAD(bn); 318 319 /* 320 * Move to head of hash chain too. 321 */ 322 BUF_HASH_RM(bn); 323 BUF_HASH_INS(bn, h); 324 } 325 326 if (ch_offset >= bp->datasize) 327 /* 328 * After all that, we still don't have enough data. 329 * Go back and try again. 330 */ 331 goto read_more; 332 333 return (bp->data[ch_offset]); 334 } 335 336 /* 337 * ch_ungetchar is a rather kludgy and limited way to push 338 * a single char onto an input file descriptor. 339 */ 340 void 341 ch_ungetchar(int c) 342 { 343 if (c != -1 && ch_ungotchar != -1) 344 error("ch_ungetchar overrun", NULL); 345 ch_ungotchar = c; 346 } 347 348 /* 349 * Close the logfile. 350 * If we haven't read all of standard input into it, do that now. 351 */ 352 void 353 end_logfile(void) 354 { 355 static int tried = FALSE; 356 357 if (logfile < 0) 358 return; 359 if (!tried && ch_fsize == -1) { 360 tried = TRUE; 361 ierror("Finishing logfile", NULL); 362 while (ch_forw_get() != EOI) 363 if (abort_sigs()) 364 break; 365 } 366 close(logfile); 367 logfile = -1; 368 free(namelogfile); 369 namelogfile = NULL; 370 } 371 372 /* 373 * Start a log file AFTER less has already been running. 374 * Invoked from the - command; see toggle_option(). 375 * Write all the existing buffered data to the log file. 376 */ 377 void 378 sync_logfile(void) 379 { 380 struct buf *bp; 381 struct bufnode *bn; 382 int warned = FALSE; 383 BLOCKNUM block; 384 BLOCKNUM nblocks; 385 386 nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE; 387 for (block = 0; block < nblocks; block++) { 388 int wrote = FALSE; 389 FOR_BUFS(bn) { 390 bp = bufnode_buf(bn); 391 if (bp->block == block) { 392 (void) write(logfile, (char *)bp->data, 393 bp->datasize); 394 wrote = TRUE; 395 break; 396 } 397 } 398 if (!wrote && !warned) { 399 error("Warning: log file is incomplete", NULL); 400 warned = TRUE; 401 } 402 } 403 } 404 405 /* 406 * Determine if a specific block is currently in one of the buffers. 407 */ 408 static int 409 buffered(BLOCKNUM block) 410 { 411 struct buf *bp; 412 struct bufnode *bn; 413 int h; 414 415 h = BUFHASH(block); 416 FOR_BUFS_IN_CHAIN(h, bn) { 417 bp = bufnode_buf(bn); 418 if (bp->block == block) 419 return (TRUE); 420 } 421 return (FALSE); 422 } 423 424 /* 425 * Seek to a specified position in the file. 426 * Return 0 if successful, non-zero if can't seek there. 427 */ 428 int 429 ch_seek(off_t pos) 430 { 431 BLOCKNUM new_block; 432 off_t len; 433 434 if (thisfile == NULL) 435 return (0); 436 437 len = ch_length(); 438 if (pos < ch_zero() || (len != -1 && pos > len)) 439 return (1); 440 441 new_block = pos / LBUFSIZE; 442 if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && 443 !buffered(new_block)) { 444 if (ch_fpos > pos) 445 return (1); 446 while (ch_fpos < pos) { 447 if (ch_forw_get() == EOI) 448 return (1); 449 if (abort_sigs()) 450 return (1); 451 } 452 return (0); 453 } 454 /* 455 * Set read pointer. 456 */ 457 ch_block = new_block; 458 ch_offset = pos % LBUFSIZE; 459 return (0); 460 } 461 462 /* 463 * Seek to the end of the file. 464 */ 465 int 466 ch_end_seek(void) 467 { 468 off_t len; 469 470 if (thisfile == NULL) 471 return (0); 472 473 if (ch_flags & CH_CANSEEK) 474 ch_fsize = filesize(ch_file); 475 476 len = ch_length(); 477 if (len != -1) 478 return (ch_seek(len)); 479 480 /* 481 * Do it the slow way: read till end of data. 482 */ 483 while (ch_forw_get() != EOI) 484 if (abort_sigs()) 485 return (1); 486 return (0); 487 } 488 489 /* 490 * Seek to the beginning of the file, or as close to it as we can get. 491 * We may not be able to seek there if input is a pipe and the 492 * beginning of the pipe is no longer buffered. 493 */ 494 int 495 ch_beg_seek(void) 496 { 497 struct bufnode *bn; 498 struct bufnode *firstbn; 499 500 /* 501 * Try a plain ch_seek first. 502 */ 503 if (ch_seek(ch_zero()) == 0) 504 return (0); 505 506 /* 507 * Can't get to position 0. 508 * Look thru the buffers for the one closest to position 0. 509 */ 510 firstbn = ch_bufhead; 511 if (firstbn == END_OF_CHAIN) 512 return (1); 513 FOR_BUFS(bn) { 514 if (bufnode_buf(bn)->block < bufnode_buf(firstbn)->block) 515 firstbn = bn; 516 } 517 ch_block = bufnode_buf(firstbn)->block; 518 ch_offset = 0; 519 return (0); 520 } 521 522 /* 523 * Return the length of the file, if known. 524 */ 525 off_t 526 ch_length(void) 527 { 528 if (thisfile == NULL) 529 return (-1); 530 if (ignore_eoi) 531 return (-1); 532 if (ch_flags & CH_NODATA) 533 return (0); 534 return (ch_fsize); 535 } 536 537 /* 538 * Return the current position in the file. 539 */ 540 off_t 541 ch_tell(void) 542 { 543 if (thisfile == NULL) 544 return (-1); 545 return ((ch_block * LBUFSIZE) + ch_offset); 546 } 547 548 /* 549 * Get the current char and post-increment the read pointer. 550 */ 551 int 552 ch_forw_get(void) 553 { 554 int c; 555 556 if (thisfile == NULL) 557 return (EOI); 558 c = ch_get(); 559 if (c == EOI) 560 return (EOI); 561 if (ch_offset < LBUFSIZE-1) { 562 ch_offset++; 563 } else { 564 ch_block ++; 565 ch_offset = 0; 566 } 567 return (c); 568 } 569 570 /* 571 * Pre-decrement the read pointer and get the new current char. 572 */ 573 int 574 ch_back_get(void) 575 { 576 if (thisfile == NULL) 577 return (EOI); 578 if (ch_offset > 0) { 579 ch_offset --; 580 } else { 581 if (ch_block <= 0) 582 return (EOI); 583 if (!(ch_flags & CH_CANSEEK) && !buffered(ch_block-1)) 584 return (EOI); 585 ch_block--; 586 ch_offset = LBUFSIZE-1; 587 } 588 return (ch_get()); 589 } 590 591 /* 592 * Set max amount of buffer space. 593 * bufspace is in units of 1024 bytes. -1 mean no limit. 594 */ 595 void 596 ch_setbufspace(int bufspace) 597 { 598 if (bufspace < 0) { 599 maxbufs = -1; 600 } else { 601 maxbufs = ((bufspace * 1024) + LBUFSIZE-1) / LBUFSIZE; 602 if (maxbufs < 1) 603 maxbufs = 1; 604 } 605 } 606 607 /* 608 * Flush (discard) any saved file state, including buffer contents. 609 */ 610 void 611 ch_flush(void) 612 { 613 struct bufnode *bn; 614 615 if (thisfile == NULL) 616 return; 617 618 if (!(ch_flags & CH_CANSEEK)) { 619 /* 620 * If input is a pipe, we don't flush buffer contents, 621 * since the contents can't be recovered. 622 */ 623 ch_fsize = -1; 624 return; 625 } 626 627 /* 628 * Initialize all the buffers. 629 */ 630 FOR_BUFS(bn) { 631 bufnode_buf(bn)->block = -1; 632 } 633 634 /* 635 * Figure out the size of the file, if we can. 636 */ 637 ch_fsize = filesize(ch_file); 638 639 /* 640 * Seek to a known position: the beginning of the file. 641 */ 642 ch_fpos = 0; 643 ch_block = 0; /* ch_fpos / LBUFSIZE; */ 644 ch_offset = 0; /* ch_fpos % LBUFSIZE; */ 645 646 if (lseek(ch_file, (off_t)0, SEEK_SET) == (off_t)-1) { 647 /* 648 * Warning only; even if the seek fails for some reason, 649 * there's a good chance we're at the beginning anyway. 650 * {{ I think this is bogus reasoning. }} 651 */ 652 error("seek error to 0", NULL); 653 } 654 } 655 656 /* 657 * Allocate a new buffer. 658 * The buffer is added to the tail of the buffer chain. 659 */ 660 static int 661 ch_addbuf(void) 662 { 663 struct buf *bp; 664 struct bufnode *bn; 665 666 /* 667 * Allocate and initialize a new buffer and link it 668 * onto the tail of the buffer list. 669 */ 670 bp = calloc(1, sizeof (struct buf)); 671 if (bp == NULL) 672 return (1); 673 ch_nbufs++; 674 bp->block = -1; 675 bn = &bp->node; 676 677 BUF_INS_TAIL(bn); 678 BUF_HASH_INS(bn, 0); 679 return (0); 680 } 681 682 /* 683 * 684 */ 685 static void 686 init_hashtbl(void) 687 { 688 int h; 689 690 for (h = 0; h < BUFHASH_SIZE; h++) { 691 thisfile->hashtbl[h].hnext = END_OF_HCHAIN(h); 692 thisfile->hashtbl[h].hprev = END_OF_HCHAIN(h); 693 } 694 } 695 696 /* 697 * Delete all buffers for this file. 698 */ 699 static void 700 ch_delbufs(void) 701 { 702 struct bufnode *bn; 703 704 while (ch_bufhead != END_OF_CHAIN) { 705 bn = ch_bufhead; 706 BUF_RM(bn); 707 free(bufnode_buf(bn)); 708 } 709 ch_nbufs = 0; 710 init_hashtbl(); 711 } 712 713 /* 714 * Is it possible to seek on a file descriptor? 715 */ 716 int 717 seekable(int f) 718 { 719 return (lseek(f, (off_t)1, SEEK_SET) != (off_t)-1); 720 } 721 722 /* 723 * Force EOF to be at the current read position. 724 * This is used after an ignore_eof read, during which the EOF may change. 725 */ 726 void 727 ch_set_eof(void) 728 { 729 ch_fsize = ch_fpos; 730 } 731 732 733 /* 734 * Initialize file state for a new file. 735 */ 736 void 737 ch_init(int f, int flags) 738 { 739 /* 740 * See if we already have a filestate for this file. 741 */ 742 thisfile = get_filestate(curr_ifile); 743 if (thisfile == NULL) { 744 /* 745 * Allocate and initialize a new filestate. 746 */ 747 thisfile = calloc(1, sizeof (struct filestate)); 748 thisfile->buflist.next = thisfile->buflist.prev = END_OF_CHAIN; 749 thisfile->nbufs = 0; 750 thisfile->flags = 0; 751 thisfile->fpos = 0; 752 thisfile->block = 0; 753 thisfile->offset = 0; 754 thisfile->file = -1; 755 thisfile->fsize = -1; 756 ch_flags = flags; 757 init_hashtbl(); 758 /* 759 * Try to seek; set CH_CANSEEK if it works. 760 */ 761 if ((flags & CH_CANSEEK) && !seekable(f)) 762 ch_flags &= ~CH_CANSEEK; 763 set_filestate(curr_ifile, (void *) thisfile); 764 } 765 if (thisfile->file == -1) 766 thisfile->file = f; 767 ch_flush(); 768 } 769 770 /* 771 * Close a filestate. 772 */ 773 void 774 ch_close(void) 775 { 776 int keepstate = FALSE; 777 778 if (thisfile == NULL) 779 return; 780 781 if (ch_flags & (CH_CANSEEK|CH_HELPFILE)) { 782 /* 783 * We can seek or re-open, so we don't need to keep buffers. 784 */ 785 ch_delbufs(); 786 } else { 787 keepstate = TRUE; 788 } 789 if (!(ch_flags & CH_KEEPOPEN)) { 790 /* 791 * We don't need to keep the file descriptor open 792 * (because we can re-open it.) 793 */ 794 close(ch_file); 795 ch_file = -1; 796 } else { 797 keepstate = TRUE; 798 } 799 if (!keepstate) { 800 /* 801 * We don't even need to keep the filestate structure. 802 */ 803 free(thisfile); 804 thisfile = NULL; 805 set_filestate(curr_ifile, NULL); 806 } 807 } 808 809 /* 810 * Return ch_flags for the current file. 811 */ 812 int 813 ch_getflags(void) 814 { 815 if (thisfile == NULL) 816 return (0); 817 return (ch_flags); 818 } 819