1 /* 2 * Copyright (C) 1984-2025 Mark Nudelman 3 * 4 * You may distribute under the terms of either the GNU General Public 5 * License or the Less License, as specified in the README file. 6 * 7 * For more information, see the README file. 8 */ 9 10 11 /* 12 * Low level character input from the input file. 13 * We use these special purpose routines which optimize moving 14 * both forward and backward from the current read pointer. 15 */ 16 17 #include "less.h" 18 #if MSDOS_COMPILER==WIN32C 19 #include <errno.h> 20 #include <windows.h> 21 #endif 22 23 typedef POSITION BLOCKNUM; 24 25 public int ignore_eoi; 26 27 /* 28 * Pool of buffers holding the most recently used blocks of the input file. 29 * The buffer pool is kept as a doubly-linked circular list, 30 * in order from most- to least-recently used. 31 * The circular list is anchored by the file state "thisfile". 32 */ 33 struct bufnode { 34 struct bufnode *next, *prev; 35 struct bufnode *hnext, *hprev; 36 }; 37 38 #define LBUFSIZE 8192 39 struct buf { 40 struct bufnode node; 41 BLOCKNUM block; 42 size_t datasize; 43 unsigned char data[LBUFSIZE]; 44 }; 45 #define bufnode_buf(bn) ((struct buf *) bn) 46 47 /* 48 * The file state is maintained in a filestate structure. 49 * A pointer to the filestate is kept in the ifile structure. 50 */ 51 #define BUFHASH_SIZE 1024 52 struct filestate { 53 struct bufnode buflist; 54 struct bufnode hashtbl[BUFHASH_SIZE]; 55 int file; 56 int flags; 57 POSITION fpos; 58 int nbufs; 59 BLOCKNUM block; 60 size_t offset; 61 POSITION fsize; 62 }; 63 64 #define ch_bufhead thisfile->buflist.next 65 #define ch_buftail thisfile->buflist.prev 66 #define ch_nbufs thisfile->nbufs 67 #define ch_block thisfile->block 68 #define ch_offset thisfile->offset 69 #define ch_fpos thisfile->fpos 70 #define ch_fsize thisfile->fsize 71 #define ch_flags thisfile->flags 72 #define ch_file thisfile->file 73 74 #define END_OF_CHAIN (&thisfile->buflist) 75 #define END_OF_HCHAIN(h) (&thisfile->hashtbl[h]) 76 #define BUFHASH(blk) ((blk) & (BUFHASH_SIZE-1)) 77 78 /* 79 * Macros to manipulate the list of buffers in thisfile->buflist. 80 */ 81 #define FOR_BUFS(bn) \ 82 for (bn = ch_bufhead; bn != END_OF_CHAIN; bn = bn->next) 83 84 #define BUF_RM(bn) \ 85 (bn)->next->prev = (bn)->prev; \ 86 (bn)->prev->next = (bn)->next; 87 88 #define BUF_INS_HEAD(bn) \ 89 (bn)->next = ch_bufhead; \ 90 (bn)->prev = END_OF_CHAIN; \ 91 ch_bufhead->prev = (bn); \ 92 ch_bufhead = (bn); 93 94 #define BUF_INS_TAIL(bn) \ 95 (bn)->next = END_OF_CHAIN; \ 96 (bn)->prev = ch_buftail; \ 97 ch_buftail->next = (bn); \ 98 ch_buftail = (bn); 99 100 /* 101 * Macros to manipulate the list of buffers in thisfile->hashtbl[n]. 102 */ 103 #define FOR_BUFS_IN_CHAIN(h,bn) \ 104 for (bn = thisfile->hashtbl[h].hnext; \ 105 bn != END_OF_HCHAIN(h); bn = bn->hnext) 106 107 #define BUF_HASH_RM(bn) \ 108 (bn)->hnext->hprev = (bn)->hprev; \ 109 (bn)->hprev->hnext = (bn)->hnext; 110 111 #define BUF_HASH_INS(bn,h) \ 112 (bn)->hnext = thisfile->hashtbl[h].hnext; \ 113 (bn)->hprev = END_OF_HCHAIN(h); \ 114 thisfile->hashtbl[h].hnext->hprev = (bn); \ 115 thisfile->hashtbl[h].hnext = (bn); 116 117 static struct filestate *thisfile; 118 static unsigned char ch_ungotchar; 119 static lbool ch_have_ungotchar = FALSE; 120 static int maxbufs = -1; 121 122 extern int autobuf; 123 extern int sigs; 124 extern int follow_mode; 125 extern lbool waiting_for_data; 126 extern constant char helpdata[]; 127 extern constant int size_helpdata; 128 extern IFILE curr_ifile; 129 #if LOGFILE 130 extern int logfile; 131 extern char *namelogfile; 132 #endif 133 134 static int ch_addbuf(); 135 136 /* 137 * Return the file position corresponding to an offset within a block. 138 */ 139 static POSITION ch_position(BLOCKNUM block, size_t offset) 140 { 141 return (block * LBUFSIZE) + (POSITION) offset; 142 } 143 144 /* 145 * Get the character pointed to by the read pointer. 146 */ 147 static int ch_get(void) 148 { 149 struct buf *bp; 150 struct bufnode *bn; 151 ssize_t n; 152 int h; 153 154 if (thisfile == NULL) 155 return (EOI); 156 157 /* 158 * Quick check for the common case where 159 * the desired char is in the head buffer. 160 */ 161 if (ch_bufhead != END_OF_CHAIN) 162 { 163 bp = bufnode_buf(ch_bufhead); 164 if (ch_block == bp->block && ch_offset < bp->datasize) 165 return bp->data[ch_offset]; 166 } 167 168 /* 169 * Look for a buffer holding the desired block. 170 */ 171 waiting_for_data = FALSE; 172 h = BUFHASH(ch_block); 173 FOR_BUFS_IN_CHAIN(h, bn) 174 { 175 bp = bufnode_buf(bn); 176 if (bp->block == ch_block) 177 { 178 if (ch_offset >= bp->datasize) 179 /* 180 * Need more data in this buffer. 181 */ 182 break; 183 goto found; 184 } 185 } 186 if (ABORT_SIGS()) 187 return (EOI); 188 if (bn == END_OF_HCHAIN(h)) 189 { 190 /* 191 * Block is not in a buffer. 192 * Take the least recently used buffer 193 * and read the desired block into it. 194 * If the LRU buffer has data in it, 195 * then maybe allocate a new buffer. 196 */ 197 if (ch_buftail == END_OF_CHAIN || 198 bufnode_buf(ch_buftail)->block != -1) 199 { 200 /* 201 * There is no empty buffer to use. 202 * Allocate a new buffer if: 203 * 1. We can't seek on this file and -b is not in effect; or 204 * 2. We haven't allocated the max buffers for this file yet. 205 */ 206 if ((autobuf && !(ch_flags & CH_CANSEEK)) || 207 (maxbufs < 0 || ch_nbufs < maxbufs)) 208 if (ch_addbuf()) 209 /* 210 * Allocation failed: turn off autobuf. 211 */ 212 autobuf = OPT_OFF; 213 } 214 bn = ch_buftail; 215 bp = bufnode_buf(bn); 216 BUF_HASH_RM(bn); /* Remove from old hash chain. */ 217 bp->block = ch_block; 218 bp->datasize = 0; 219 BUF_HASH_INS(bn, h); /* Insert into new hash chain. */ 220 } 221 222 for (;;) 223 { 224 lbool read_again; 225 POSITION len; 226 POSITION pos = ch_position(ch_block, bp->datasize); 227 lbool read_pipe_at_eof = FALSE; 228 if ((len = ch_length()) != NULL_POSITION && pos >= len) 229 { 230 /* 231 * Apparently at end of file. 232 * Double-check the file size in case it has changed. 233 */ 234 ch_resize(); 235 if ((len = ch_length()) != NULL_POSITION && pos >= len) 236 { 237 if (ch_flags & (CH_CANSEEK|CH_HELPFILE)) 238 return (EOI); 239 /* ch_length doesn't work for pipes, so just try to 240 * read from the pipe to see if more data has appeared. 241 * This can happen only in limited situations, such as 242 * a fifo that the writer has closed and reopened. */ 243 read_pipe_at_eof = TRUE; 244 } 245 } 246 247 if (pos != ch_fpos) 248 { 249 /* 250 * Not at the correct position: must seek. 251 * If input is a pipe, we're in trouble (can't seek on a pipe). 252 * Some data has been lost: just return "?". 253 */ 254 if (!(ch_flags & CH_CANSEEK)) 255 return ('?'); 256 if (less_lseek(ch_file, (less_off_t)pos, SEEK_SET) == BAD_LSEEK) 257 { 258 error("seek error", NULL_PARG); 259 clear_eol(); 260 return (EOI); 261 } 262 ch_fpos = pos; 263 } 264 265 /* 266 * Read the block. 267 * If we read less than a full block, that's ok. 268 * We use partial block and pick up the rest next time. 269 */ 270 if (ch_have_ungotchar) 271 { 272 bp->data[bp->datasize] = ch_ungotchar; 273 n = 1; 274 ch_have_ungotchar = FALSE; 275 } else if (ch_flags & CH_HELPFILE) 276 { 277 bp->data[bp->datasize] = (unsigned char) helpdata[ch_fpos]; 278 n = 1; 279 } else 280 { 281 n = iread(ch_file, &bp->data[bp->datasize], LBUFSIZE - bp->datasize); 282 } 283 284 read_again = FALSE; 285 if (n == READ_INTR) 286 return (EOI); 287 if (n == READ_AGAIN) 288 { 289 read_again = TRUE; 290 n = 0; 291 } 292 if (n < 0) 293 { 294 #if MSDOS_COMPILER==WIN32C 295 if (errno != EPIPE) 296 #endif 297 { 298 error("read error", NULL_PARG); 299 clear_eol(); 300 } 301 n = 0; 302 } 303 304 #if LOGFILE 305 /* 306 * If we have a log file, write the new data to it. 307 */ 308 if (secure_allow(SF_LOGFILE)) 309 { 310 if (logfile >= 0 && n > 0) 311 write(logfile, &bp->data[bp->datasize], (size_t) n); 312 } 313 #endif 314 315 ch_fpos += n; 316 bp->datasize += (size_t) n; 317 if (read_pipe_at_eof) 318 ch_set_eof(); /* update length of pipe */ 319 320 if (n == 0) 321 { 322 /* Either end of file or no data available. 323 * read_again indicates the latter. */ 324 if (!read_again) 325 ch_fsize = pos; 326 if (ignore_eoi || read_again) 327 { 328 /* Wait a while, then try again. */ 329 if (!waiting_for_data) 330 { 331 PARG parg; 332 parg.p_string = wait_message(); 333 ixerror("%s", &parg); 334 waiting_for_data = TRUE; 335 } 336 sleep_ms(50); /* Reduce system load */ 337 } 338 if (ignore_eoi && follow_mode == FOLLOW_NAME && curr_ifile_changed()) 339 { 340 /* screen_trashed=2 causes make_display to reopen the file. */ 341 screen_trashed_num(2); 342 return (EOI); 343 } 344 if (sigs) 345 return (EOI); 346 if (read_pipe_at_eof) 347 /* No new data; we are still at EOF on the pipe. */ 348 return (EOI); 349 } 350 351 found: 352 if (ch_bufhead != bn) 353 { 354 /* 355 * Move the buffer to the head of the buffer chain. 356 * This orders the buffer chain, most- to least-recently used. 357 */ 358 BUF_RM(bn); 359 BUF_INS_HEAD(bn); 360 361 /* 362 * Move to head of hash chain too. 363 */ 364 BUF_HASH_RM(bn); 365 BUF_HASH_INS(bn, h); 366 } 367 368 if (ch_offset < bp->datasize) 369 break; 370 /* 371 * After all that, we still don't have enough data. 372 * Go back and try again. 373 */ 374 } 375 return (bp->data[ch_offset]); 376 } 377 378 /* 379 * ch_ungetchar is a rather kludgy and limited way to push 380 * a single char onto an input file descriptor. 381 */ 382 public void ch_ungetchar(int c) 383 { 384 if (c < 0) 385 ch_have_ungotchar = FALSE; 386 else 387 { 388 if (ch_have_ungotchar) 389 error("ch_ungetchar overrun", NULL_PARG); 390 ch_ungotchar = (unsigned char) c; 391 ch_have_ungotchar = TRUE; 392 } 393 } 394 395 #if LOGFILE 396 /* 397 * Close the logfile. 398 * If we haven't read all of standard input into it, do that now. 399 */ 400 public void end_logfile(void) 401 { 402 static lbool tried = FALSE; 403 404 if (logfile < 0) 405 return; 406 if (!tried && ch_fsize == NULL_POSITION) 407 { 408 tried = TRUE; 409 ierror("Finishing logfile", NULL_PARG); 410 while (ch_forw_get() != EOI) 411 if (ABORT_SIGS()) 412 break; 413 } 414 close(logfile); 415 logfile = -1; 416 free(namelogfile); 417 namelogfile = NULL; 418 putstr("\n"); 419 flush(); 420 } 421 422 /* 423 * Start a log file AFTER less has already been running. 424 * Invoked from the - command; see toggle_option(). 425 * Write all the existing buffered data to the log file. 426 */ 427 public void sync_logfile(void) 428 { 429 struct buf *bp; 430 struct bufnode *bn; 431 lbool warned = FALSE; 432 int h; 433 BLOCKNUM block; 434 BLOCKNUM nblocks; 435 436 if (logfile < 0) 437 return; 438 nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE; 439 for (block = 0; block < nblocks; block++) 440 { 441 lbool wrote = FALSE; 442 h = BUFHASH(block); 443 FOR_BUFS_IN_CHAIN(h, bn) 444 { 445 bp = bufnode_buf(bn); 446 if (bp->block == block) 447 { 448 write(logfile, bp->data, bp->datasize); 449 wrote = TRUE; 450 break; 451 } 452 } 453 if (!wrote && !warned) 454 { 455 error("Warning: log file is incomplete", 456 NULL_PARG); 457 warned = TRUE; 458 } 459 } 460 } 461 462 #endif 463 464 /* 465 * Determine if a specific block is currently in one of the buffers. 466 */ 467 static lbool buffered(BLOCKNUM block) 468 { 469 struct buf *bp; 470 struct bufnode *bn; 471 int h; 472 473 h = BUFHASH(block); 474 FOR_BUFS_IN_CHAIN(h, bn) 475 { 476 bp = bufnode_buf(bn); 477 if (bp->block == block) 478 return (TRUE); 479 } 480 return (FALSE); 481 } 482 483 /* 484 * Seek to a specified position in the file. 485 * Return 0 if successful, non-zero if can't seek there. 486 */ 487 public int ch_seek(POSITION pos) 488 { 489 BLOCKNUM new_block; 490 POSITION len; 491 492 if (thisfile == NULL) 493 return (0); 494 495 len = ch_length(); 496 if (pos < ch_zero() || (len != NULL_POSITION && pos > len)) 497 return (1); 498 499 new_block = pos / LBUFSIZE; 500 if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && !buffered(new_block)) 501 { 502 if (ch_fpos > pos) 503 return (1); 504 while (ch_fpos < pos) 505 { 506 if (ch_forw_get() == EOI) 507 return (1); 508 if (ABORT_SIGS()) 509 return (1); 510 } 511 return (0); 512 } 513 /* 514 * Set read pointer. 515 */ 516 ch_block = new_block; 517 ch_offset = (size_t) (pos % LBUFSIZE); 518 return (0); 519 } 520 521 /* 522 * Seek to the end of the file. 523 */ 524 public int ch_end_seek(void) 525 { 526 POSITION len; 527 528 if (thisfile == NULL) 529 return (0); 530 531 if (ch_flags & CH_CANSEEK) 532 ch_fsize = filesize(ch_file); 533 534 len = ch_length(); 535 if (len != NULL_POSITION) 536 return (ch_seek(len)); 537 538 /* 539 * Do it the slow way: read till end of data. 540 */ 541 while (ch_forw_get() != EOI) 542 if (ABORT_SIGS()) 543 return (1); 544 return (0); 545 } 546 547 /* 548 * Seek to the last position in the file that is currently buffered. 549 */ 550 public int ch_end_buffer_seek(void) 551 { 552 struct buf *bp; 553 struct bufnode *bn; 554 POSITION buf_pos; 555 POSITION end_pos; 556 557 if (thisfile == NULL || (ch_flags & CH_CANSEEK)) 558 return (ch_end_seek()); 559 560 end_pos = 0; 561 FOR_BUFS(bn) 562 { 563 bp = bufnode_buf(bn); 564 buf_pos = ch_position(bp->block, bp->datasize); 565 if (buf_pos > end_pos) 566 end_pos = buf_pos; 567 } 568 569 return (ch_seek(end_pos)); 570 } 571 572 /* 573 * Seek to the beginning of the file, or as close to it as we can get. 574 * We may not be able to seek there if input is a pipe and the 575 * beginning of the pipe is no longer buffered. 576 */ 577 public int ch_beg_seek(void) 578 { 579 struct bufnode *bn; 580 struct bufnode *firstbn; 581 582 /* 583 * Try a plain ch_seek first. 584 */ 585 if (ch_seek(ch_zero()) == 0) 586 return (0); 587 588 /* 589 * Can't get to position 0. 590 * Look thru the buffers for the one closest to position 0. 591 */ 592 firstbn = ch_bufhead; 593 if (firstbn == END_OF_CHAIN) 594 return (1); 595 FOR_BUFS(bn) 596 { 597 if (bufnode_buf(bn)->block < bufnode_buf(firstbn)->block) 598 firstbn = bn; 599 } 600 ch_block = bufnode_buf(firstbn)->block; 601 ch_offset = 0; 602 return (0); 603 } 604 605 /* 606 * Return the length of the file, if known. 607 */ 608 public POSITION ch_length(void) 609 { 610 if (thisfile == NULL) 611 return (NULL_POSITION); 612 if (ignore_eoi) 613 return (NULL_POSITION); 614 if (ch_flags & CH_HELPFILE) 615 return (size_helpdata); 616 if (ch_flags & CH_NODATA) 617 return (0); 618 return (ch_fsize); 619 } 620 621 /* 622 * Update the file size, in case it has changed. 623 */ 624 public void ch_resize(void) 625 { 626 POSITION fsize; 627 628 if (!(ch_flags & CH_CANSEEK)) 629 return; 630 fsize = filesize(ch_file); 631 if (fsize != NULL_POSITION) 632 ch_fsize = fsize; 633 } 634 635 /* 636 * Return the current position in the file. 637 */ 638 public POSITION ch_tell(void) 639 { 640 if (thisfile == NULL) 641 return (NULL_POSITION); 642 return ch_position(ch_block, ch_offset); 643 } 644 645 /* 646 * Get the current char and post-increment the read pointer. 647 */ 648 public int ch_forw_get(void) 649 { 650 int c; 651 652 if (thisfile == NULL) 653 return (EOI); 654 c = ch_get(); 655 if (c == EOI) 656 return (EOI); 657 if (ch_offset < LBUFSIZE-1) 658 ch_offset++; 659 else 660 { 661 ch_block ++; 662 ch_offset = 0; 663 } 664 return (c); 665 } 666 667 /* 668 * Pre-decrement the read pointer and get the new current char. 669 */ 670 public int ch_back_get(void) 671 { 672 if (thisfile == NULL) 673 return (EOI); 674 if (ch_offset > 0) 675 ch_offset --; 676 else 677 { 678 if (ch_block <= 0) 679 return (EOI); 680 if (!(ch_flags & CH_CANSEEK) && !buffered(ch_block-1)) 681 return (EOI); 682 ch_block--; 683 ch_offset = LBUFSIZE-1; 684 } 685 return (ch_get()); 686 } 687 688 /* 689 * Set max amount of buffer space. 690 * bufspace is in units of 1024 bytes. -1 mean no limit. 691 */ 692 public void ch_setbufspace(ssize_t bufspace) 693 { 694 if (bufspace < 0) 695 maxbufs = -1; 696 else 697 { 698 size_t lbufk = LBUFSIZE / 1024; 699 maxbufs = (int) (bufspace / lbufk + (bufspace % lbufk != 0)); 700 if (maxbufs < 1) 701 maxbufs = 1; 702 } 703 } 704 705 /* 706 * Flush (discard) any saved file state, including buffer contents. 707 */ 708 public void ch_flush(void) 709 { 710 struct bufnode *bn; 711 712 if (thisfile == NULL) 713 return; 714 715 if (!(ch_flags & CH_CANSEEK)) 716 { 717 /* 718 * If input is a pipe, we don't flush buffer contents, 719 * since the contents can't be recovered. 720 */ 721 ch_fsize = NULL_POSITION; 722 return; 723 } 724 725 /* 726 * Initialize all the buffers. 727 */ 728 FOR_BUFS(bn) 729 { 730 bufnode_buf(bn)->block = -1; 731 } 732 733 /* 734 * Seek to a known position: the beginning of the file. 735 */ 736 ch_fpos = 0; 737 ch_block = 0; /* ch_fpos / LBUFSIZE; */ 738 ch_offset = 0; /* ch_fpos % LBUFSIZE; */ 739 740 if (ch_flags & CH_NOTRUSTSIZE) 741 { 742 ch_fsize = NULL_POSITION; 743 ch_flags &= ~CH_CANSEEK; 744 } else 745 { 746 ch_fsize = (ch_flags & CH_HELPFILE) ? size_helpdata : filesize(ch_file); 747 } 748 749 if (less_lseek(ch_file, (less_off_t)0, SEEK_SET) == BAD_LSEEK) 750 { 751 /* 752 * Warning only; even if the seek fails for some reason, 753 * there's a good chance we're at the beginning anyway. 754 * {{ I think this is bogus reasoning. }} 755 */ 756 error("seek error to 0", NULL_PARG); 757 } 758 } 759 760 /* 761 * Allocate a new buffer. 762 * The buffer is added to the tail of the buffer chain. 763 */ 764 static int ch_addbuf(void) 765 { 766 struct buf *bp; 767 struct bufnode *bn; 768 769 /* 770 * Allocate and initialize a new buffer and link it 771 * onto the tail of the buffer list. 772 */ 773 bp = (struct buf *) calloc(1, sizeof(struct buf)); 774 if (bp == NULL) 775 return (1); 776 ch_nbufs++; 777 bp->block = -1; 778 bn = &bp->node; 779 780 BUF_INS_TAIL(bn); 781 BUF_HASH_INS(bn, 0); 782 return (0); 783 } 784 785 /* 786 * 787 */ 788 static void init_hashtbl(void) 789 { 790 int h; 791 792 for (h = 0; h < BUFHASH_SIZE; h++) 793 { 794 thisfile->hashtbl[h].hnext = END_OF_HCHAIN(h); 795 thisfile->hashtbl[h].hprev = END_OF_HCHAIN(h); 796 } 797 } 798 799 /* 800 * Delete all buffers for this file. 801 */ 802 static void ch_delbufs(void) 803 { 804 struct bufnode *bn; 805 806 while (ch_bufhead != END_OF_CHAIN) 807 { 808 bn = ch_bufhead; 809 BUF_RM(bn); 810 free(bufnode_buf(bn)); 811 } 812 ch_nbufs = 0; 813 init_hashtbl(); 814 } 815 816 /* 817 * Is it possible to seek on a file descriptor? 818 */ 819 public int seekable(int f) 820 { 821 #if MSDOS_COMPILER 822 extern int fd0; 823 if (f == fd0 && !isatty(fd0)) 824 { 825 /* 826 * In MS-DOS, pipes are seekable. Check for 827 * standard input, and pretend it is not seekable. 828 */ 829 return (0); 830 } 831 #endif 832 return (less_lseek(f, (less_off_t)1, SEEK_SET) != BAD_LSEEK); 833 } 834 835 /* 836 * Force EOF to be at the current read position. 837 * This is used after an ignore_eof read, during which the EOF may change. 838 */ 839 public void ch_set_eof(void) 840 { 841 if (ch_fsize != NULL_POSITION && ch_fsize < ch_fpos) 842 ch_fsize = ch_fpos; 843 } 844 845 846 /* 847 * Initialize file state for a new file. 848 */ 849 public void ch_init(int f, int flags, ssize_t nread) 850 { 851 /* 852 * See if we already have a filestate for this file. 853 */ 854 thisfile = (struct filestate *) get_filestate(curr_ifile); 855 if (thisfile == NULL) 856 { 857 /* 858 * Allocate and initialize a new filestate. 859 */ 860 thisfile = (struct filestate *) 861 ecalloc(1, sizeof(struct filestate)); 862 thisfile->buflist.next = thisfile->buflist.prev = END_OF_CHAIN; 863 thisfile->nbufs = 0; 864 thisfile->flags = flags; 865 thisfile->fpos = 0; 866 thisfile->block = 0; 867 thisfile->offset = 0; 868 thisfile->file = -1; 869 thisfile->fsize = NULL_POSITION; 870 init_hashtbl(); 871 /* 872 * Try to seek; set CH_CANSEEK if it works. 873 */ 874 if ((flags & CH_CANSEEK) && !seekable(f)) 875 ch_flags &= ~CH_CANSEEK; 876 set_filestate(curr_ifile, (void *) thisfile); 877 } 878 if (thisfile->file == -1) 879 thisfile->file = f; 880 881 /* 882 * Figure out the size of the file, if we can. 883 */ 884 ch_fsize = (flags & CH_HELPFILE) ? size_helpdata : filesize(ch_file); 885 886 /* 887 * This is a kludge to workaround a Linux kernel bug: files in some 888 * pseudo filesystems like /proc and tracefs have a size of 0 according 889 * to fstat() but have readable data. 890 */ 891 if (ch_fsize == 0 && nread > 0) 892 { 893 ch_flags |= CH_NOTRUSTSIZE; 894 } 895 896 ch_flush(); 897 } 898 899 /* 900 * Close a filestate. 901 */ 902 public void ch_close(void) 903 { 904 lbool keepstate = FALSE; 905 906 if (thisfile == NULL) 907 return; 908 909 if ((ch_flags & (CH_CANSEEK|CH_POPENED|CH_HELPFILE)) && !(ch_flags & CH_KEEPOPEN)) 910 { 911 /* 912 * We can seek or re-open, so we don't need to keep buffers. 913 */ 914 ch_delbufs(); 915 } else 916 keepstate = TRUE; 917 if (!(ch_flags & CH_KEEPOPEN)) 918 { 919 /* 920 * We don't need to keep the file descriptor open 921 * (because we can re-open it.) 922 * But don't really close it if it was opened via popen(), 923 * because pclose() wants to close it. 924 */ 925 if (!(ch_flags & (CH_POPENED|CH_HELPFILE))) 926 close(ch_file); 927 ch_file = -1; 928 } else 929 keepstate = TRUE; 930 if (!keepstate) 931 { 932 /* 933 * We don't even need to keep the filestate structure. 934 */ 935 free(thisfile); 936 thisfile = NULL; 937 set_filestate(curr_ifile, (void *) NULL); 938 } 939 } 940 941 /* 942 * Return ch_flags for the current file. 943 */ 944 public int ch_getflags(void) 945 { 946 if (thisfile == NULL) 947 return (0); 948 return (ch_flags); 949 } 950 951 #if 0 952 static void ch_dump(struct filestate *fs) 953 { 954 struct buf *bp; 955 struct bufnode *bn; 956 unsigned char *s; 957 958 if (fs == NULL) 959 { 960 printf(" --no filestate\n"); 961 return; 962 } 963 printf(" file %d, flags %x, fpos %x, fsize %x, blk/off %x/%x\n", 964 fs->file, fs->flags, fs->fpos, 965 fs->fsize, fs->block, fs->offset); 966 printf(" %d bufs:\n", fs->nbufs); 967 for (bn = fs->next; bn != &fs->buflist; bn = bn->next) 968 { 969 bp = bufnode_buf(bn); 970 printf("%x: blk %x, size %x \"", 971 bp, bp->block, bp->datasize); 972 for (s = bp->data; s < bp->data + 30; s++) 973 if (*s >= ' ' && *s < 0x7F) 974 printf("%c", *s); 975 else 976 printf("."); 977 printf("\"\n"); 978 } 979 } 980 #endif 981