ch.c revision 89019
1114402Sru/* 2151497Sru * Copyright (C) 1984-2000 Mark Nudelman 3151497Sru * 4114402Sru * You may distribute under the terms of either the GNU General Public 5114402Sru * License or the Less License, as specified in the README file. 6114402Sru * 7114402Sru * For more information about less, or for information on how to 8114402Sru * contact the author, see the README file. 9114402Sru */ 10114402Sru 11114402Sru 12114402Sru/* 13114402Sru * Low level character input from the input file. 14114402Sru * We use these special purpose routines which optimize moving 15114402Sru * both forward and backward from the current read pointer. 16114402Sru */ 17114402Sru 18114402Sru#include "less.h" 19114402Sru#if MSDOS_COMPILER==WIN32C 20151497Sru#include <errno.h> 21114402Sru#include <windows.h> 22114402Sru#endif 23114402Sru 24114402Srutypedef POSITION BLOCKNUM; 25114402Sru 26114402Srupublic int ignore_eoi; 27114402Sru 28114402Sru/* 29114402Sru * Pool of buffers holding the most recently used blocks of the input file. 30114402Sru * The buffer pool is kept as a doubly-linked circular list, 31114402Sru * in order from most- to least-recently used. 32114402Sru * The circular list is anchored by the file state "thisfile". 33114402Sru */ 34114402Sru#define LBUFSIZE 8192 35114402Srustruct buf { 36114402Sru struct buf *next, *prev; 37114402Sru struct buf *hnext, *hprev; 38114402Sru BLOCKNUM block; 39114402Sru unsigned int datasize; 40114402Sru unsigned char data[LBUFSIZE]; 41114402Sru}; 42114402Sru 43114402Srustruct buflist { 44114402Sru /* -- Following members must match struct buf */ 45114402Sru struct buf *buf_next, *buf_prev; 46114402Sru struct buf *buf_hnext, *buf_hprev; 47114402Sru}; 48114402Sru 49114402Sru/* 50114402Sru * The file state is maintained in a filestate structure. 51114402Sru * A pointer to the filestate is kept in the ifile structure. 52114402Sru */ 53114402Sru#define BUFHASH_SIZE 64 54114402Srustruct filestate { 55114402Sru struct buf *buf_next, *buf_prev; 56114402Sru struct buflist hashtbl[BUFHASH_SIZE]; 57114402Sru int file; 58114402Sru int flags; 59114402Sru POSITION fpos; 60114402Sru int nbufs; 61114402Sru BLOCKNUM block; 62114402Sru unsigned int offset; 63114402Sru POSITION fsize; 64114402Sru}; 65114402Sru 66114402Sru#define ch_bufhead thisfile->buf_next 67114402Sru#define ch_buftail thisfile->buf_prev 68114402Sru#define ch_nbufs thisfile->nbufs 69114402Sru#define ch_block thisfile->block 70114402Sru#define ch_offset thisfile->offset 71114402Sru#define ch_fpos thisfile->fpos 72114402Sru#define ch_fsize thisfile->fsize 73114402Sru#define ch_flags thisfile->flags 74114402Sru#define ch_file thisfile->file 75114402Sru 76114402Sru#define END_OF_CHAIN ((struct buf *)&thisfile->buf_next) 77114402Sru#define END_OF_HCHAIN(h) ((struct buf *)&thisfile->hashtbl[h]) 78114402Sru#define BUFHASH(blk) ((blk) & (BUFHASH_SIZE-1)) 79114402Sru 80114402Sru#define FOR_BUFS_IN_CHAIN(h,bp) \ 81114402Sru for (bp = thisfile->hashtbl[h].buf_hnext; \ 82114402Sru bp != END_OF_HCHAIN(h); bp = bp->hnext) 83114402Sru 84114402Sru#define HASH_RM(bp) \ 85114402Sru (bp)->hnext->hprev = (bp)->hprev; \ 86114402Sru (bp)->hprev->hnext = (bp)->hnext; 87114402Sru 88114402Sru#define HASH_INS(bp,h) \ 89114402Sru (bp)->hnext = thisfile->hashtbl[h].buf_hnext; \ 90114402Sru (bp)->hprev = END_OF_HCHAIN(h); \ 91114402Sru thisfile->hashtbl[h].buf_hnext->hprev = (bp); \ 92114402Sru thisfile->hashtbl[h].buf_hnext = (bp); 93114402Sru 94114402Srustatic struct filestate *thisfile; 95114402Srustatic int ch_ungotchar = -1; 96114402Sru 97114402Sruextern int autobuf; 98114402Sruextern int sigs; 99114402Sruextern int cbufs; 100114402Sruextern int secure; 101114402Sruextern constant char helpdata[]; 102114402Sruextern constant int size_helpdata; 103114402Sruextern IFILE curr_ifile; 104114402Sru#if LOGFILE 105114402Sruextern int logfile; 106114402Sruextern char *namelogfile; 107114402Sru#endif 108114402Sru 109114402Srustatic int ch_addbuf(); 110114402Sru 111114402Sru 112114402Sru/* 113114402Sru * Get the character pointed to by the read pointer. 114114402Sru * ch_get() is a macro which is more efficient to call 115114402Sru * than fch_get (the function), in the usual case 116114402Sru * that the block desired is at the head of the chain. 117114402Sru */ 118114402Sru#define ch_get() ((ch_block == ch_bufhead->block && \ 119114402Sru ch_offset < ch_bufhead->datasize) ? \ 120114402Sru ch_bufhead->data[ch_offset] : fch_get()) 121114402Sru int 122114402Srufch_get() 123114402Sru{ 124114402Sru register struct buf *bp; 125114402Sru register int n; 126114402Sru register int slept; 127114402Sru register int h; 128114402Sru POSITION pos; 129114402Sru POSITION len; 130114402Sru 131114402Sru slept = FALSE; 132114402Sru 133114402Sru /* 134114402Sru * Look for a buffer holding the desired block. 135114402Sru */ 136114402Sru h = BUFHASH(ch_block); 137114402Sru FOR_BUFS_IN_CHAIN(h, bp) 138114402Sru { 139114402Sru if (bp->block == ch_block) 140114402Sru { 141114402Sru if (ch_offset >= bp->datasize) 142114402Sru /* 143114402Sru * Need more data in this buffer. 144114402Sru */ 145114402Sru goto read_more; 146114402Sru goto found; 147114402Sru } 148114402Sru } 149114402Sru /* 150114402Sru * Block is not in a buffer. 151114402Sru * Take the least recently used buffer 152114402Sru * and read the desired block into it. 153114402Sru * If the LRU buffer has data in it, 154114402Sru * then maybe allocate a new buffer. 155114402Sru */ 156114402Sru if (ch_buftail == END_OF_CHAIN || ch_buftail->block != -1) 157114402Sru { 158114402Sru /* 159114402Sru * There is no empty buffer to use. 160114402Sru * Allocate a new buffer if: 161114402Sru * 1. We can't seek on this file and -b is not in effect; or 162114402Sru * 2. We haven't allocated the max buffers for this file yet. 163114402Sru */ 164114402Sru if ((autobuf && !(ch_flags & CH_CANSEEK)) || 165114402Sru (cbufs == -1 || ch_nbufs < cbufs)) 166114402Sru if (ch_addbuf()) 167114402Sru /* 168114402Sru * Allocation failed: turn off autobuf. 169114402Sru */ 170114402Sru autobuf = OPT_OFF; 171114402Sru } 172114402Sru bp = ch_buftail; 173114402Sru HASH_RM(bp); /* Remove from old hash chain. */ 174114402Sru bp->block = ch_block; 175114402Sru bp->datasize = 0; 176114402Sru HASH_INS(bp, h); /* Insert into new hash chain. */ 177114402Sru 178114402Sru read_more: 179114402Sru pos = (ch_block * LBUFSIZE) + bp->datasize; 180114402Sru if ((len = ch_length()) != NULL_POSITION && pos >= len) 181114402Sru /* 182114402Sru * At end of file. 183114402Sru */ 184114402Sru return (EOI); 185114402Sru 186114402Sru if (pos != ch_fpos) 187114402Sru { 188114402Sru /* 189114402Sru * Not at the correct position: must seek. 190114402Sru * If input is a pipe, we're in trouble (can't seek on a pipe). 191114402Sru * Some data has been lost: just return "?". 192114402Sru */ 193114402Sru if (!(ch_flags & CH_CANSEEK)) 194114402Sru return ('?'); 195114402Sru if (lseek(ch_file, (off_t)pos, 0) == BAD_LSEEK) 196114402Sru { 197114402Sru error("seek error", NULL_PARG); 198114402Sru clear_eol(); 199114402Sru return (EOI); 200114402Sru } 201114402Sru ch_fpos = pos; 202114402Sru } 203114402Sru 204114402Sru /* 205114402Sru * Read the block. 206114402Sru * If we read less than a full block, that's ok. 207114402Sru * We use partial block and pick up the rest next time. 208114402Sru */ 209114402Sru if (ch_ungotchar != -1) 210114402Sru { 211114402Sru bp->data[bp->datasize] = ch_ungotchar; 212114402Sru n = 1; 213114402Sru ch_ungotchar = -1; 214114402Sru } else if (ch_flags & CH_HELPFILE) 215114402Sru { 216114402Sru bp->data[bp->datasize] = helpdata[ch_fpos]; 217114402Sru n = 1; 218114402Sru } else 219114402Sru { 220114402Sru n = iread(ch_file, &bp->data[bp->datasize], 221114402Sru (unsigned int)(LBUFSIZE - bp->datasize)); 222114402Sru } 223114402Sru 224114402Sru if (n == READ_INTR) 225114402Sru return (EOI); 226114402Sru if (n < 0) 227114402Sru { 228114402Sru#if MSDOS_COMPILER==WIN32C 229114402Sru if (errno != EPIPE) 230114402Sru#endif 231114402Sru { 232114402Sru error("read error", NULL_PARG); 233114402Sru clear_eol(); 234114402Sru } 235114402Sru n = 0; 236114402Sru } 237114402Sru 238114402Sru#if LOGFILE 239114402Sru /* 240114402Sru * If we have a log file, write the new data to it. 241114402Sru */ 242114402Sru if (!secure && logfile >= 0 && n > 0) 243114402Sru write(logfile, (char *) &bp->data[bp->datasize], n); 244114402Sru#endif 245114402Sru 246114402Sru ch_fpos += n; 247114402Sru bp->datasize += n; 248114402Sru 249114402Sru /* 250114402Sru * If we have read to end of file, set ch_fsize to indicate 251114402Sru * the position of the end of file. 252114402Sru */ 253114402Sru if (n == 0) 254114402Sru { 255114402Sru ch_fsize = pos; 256114402Sru if (ignore_eoi) 257114402Sru { 258114402Sru /* 259114402Sru * We are ignoring EOF. 260114402Sru * Wait a while, then try again. 261114402Sru */ 262114402Sru if (!slept) 263114402Sru { 264114402Sru PARG parg; 265114402Sru parg.p_string = wait_message(); 266114402Sru ierror("%s", &parg); 267114402Sru } 268114402Sru#if !MSDOS_COMPILER 269114402Sru sleep(1); 270114402Sru#else 271114402Sru#if MSDOS_COMPILER==WIN32C 272114402Sru Sleep(1000); 273114402Sru#endif 274114402Sru#endif 275114402Sru slept = TRUE; 276114402Sru } 277114402Sru if (sigs) 278114402Sru return (EOI); 279114402Sru } 280114402Sru 281114402Sru found: 282114402Sru if (ch_bufhead != bp) 283114402Sru { 284114402Sru /* 285114402Sru * Move the buffer to the head of the buffer chain. 286114402Sru * This orders the buffer chain, most- to least-recently used. 287114402Sru */ 288114402Sru bp->next->prev = bp->prev; 289114402Sru bp->prev->next = bp->next; 290114402Sru bp->next = ch_bufhead; 291114402Sru bp->prev = END_OF_CHAIN; 292114402Sru ch_bufhead->prev = bp; 293114402Sru ch_bufhead = bp; 294114402Sru 295114402Sru /* 296114402Sru * Move to head of hash chain too. 297114402Sru */ 298114402Sru HASH_RM(bp); 299114402Sru HASH_INS(bp, h); 300114402Sru } 301114402Sru 302114402Sru if (ch_offset >= bp->datasize) 303114402Sru /* 304114402Sru * After all that, we still don't have enough data. 305114402Sru * Go back and try again. 306114402Sru */ 307114402Sru goto read_more; 308114402Sru 309114402Sru return (bp->data[ch_offset]); 310114402Sru} 311114402Sru 312114402Sru/* 313114402Sru * ch_ungetchar is a rather kludgy and limited way to push 314114402Sru * a single char onto an input file descriptor. 315114402Sru */ 316114402Sru public void 317114402Sruch_ungetchar(c) 318114402Sru int c; 319114402Sru{ 320114402Sru if (c != -1 && ch_ungotchar != -1) 321114402Sru error("ch_ungetchar overrun", NULL_PARG); 322114402Sru ch_ungotchar = c; 323114402Sru} 324114402Sru 325114402Sru#if LOGFILE 326114402Sru/* 327114402Sru * Close the logfile. 328114402Sru * If we haven't read all of standard input into it, do that now. 329114402Sru */ 330114402Sru public void 331114402Sruend_logfile() 332114402Sru{ 333114402Sru static int tried = FALSE; 334114402Sru 335114402Sru if (logfile < 0) 336114402Sru return; 337114402Sru if (!tried && ch_fsize == NULL_POSITION) 338114402Sru { 339114402Sru tried = TRUE; 340114402Sru ierror("Finishing logfile", NULL_PARG); 341114402Sru while (ch_forw_get() != EOI) 342114402Sru if (ABORT_SIGS()) 343114402Sru break; 344114402Sru } 345114402Sru close(logfile); 346114402Sru logfile = -1; 347114402Sru namelogfile = NULL; 348114402Sru} 349114402Sru 350114402Sru/* 351114402Sru * Start a log file AFTER less has already been running. 352114402Sru * Invoked from the - command; see toggle_option(). 353151497Sru * Write all the existing buffered data to the log file. 354114402Sru */ 355114402Sru public void 356114402Srusync_logfile() 357114402Sru{ 358114402Sru register struct buf *bp; 359114402Sru int warned = FALSE; 360114402Sru BLOCKNUM block; 361114402Sru BLOCKNUM nblocks; 362114402Sru 363114402Sru nblocks = (ch_fpos + LBUFSIZE - 1) / LBUFSIZE; 364114402Sru for (block = 0; block < nblocks; block++) 365114402Sru { 366114402Sru for (bp = ch_bufhead; ; bp = bp->next) 367114402Sru { 368114402Sru if (bp == END_OF_CHAIN) 369114402Sru { 370114402Sru if (!warned) 371114402Sru { 372114402Sru error("Warning: log file is incomplete", 373114402Sru NULL_PARG); 374114402Sru warned = TRUE; 375114402Sru } 376114402Sru break; 377114402Sru } 378114402Sru if (bp->block == block) 379114402Sru { 380114402Sru write(logfile, (char *) bp->data, bp->datasize); 381114402Sru break; 382114402Sru } 383114402Sru } 384114402Sru } 385114402Sru} 386114402Sru 387114402Sru#endif 388114402Sru 389114402Sru/* 390114402Sru * Determine if a specific block is currently in one of the buffers. 391114402Sru */ 392114402Sru static int 393114402Srubuffered(block) 394114402Sru BLOCKNUM block; 395114402Sru{ 396114402Sru register struct buf *bp; 397114402Sru register int h; 398114402Sru 399114402Sru h = BUFHASH(block); 400114402Sru FOR_BUFS_IN_CHAIN(h, bp) 401114402Sru { 402114402Sru if (bp->block == block) 403114402Sru return (TRUE); 404114402Sru } 405114402Sru return (FALSE); 406114402Sru} 407114402Sru 408114402Sru/* 409114402Sru * Seek to a specified position in the file. 410114402Sru * Return 0 if successful, non-zero if can't seek there. 411114402Sru */ 412114402Sru public int 413114402Sruch_seek(pos) 414114402Sru register POSITION pos; 415114402Sru{ 416114402Sru BLOCKNUM new_block; 417114402Sru POSITION len; 418114402Sru 419114402Sru len = ch_length(); 420114402Sru if (pos < ch_zero() || (len != NULL_POSITION && pos > len)) 421114402Sru return (1); 422114402Sru 423114402Sru new_block = pos / LBUFSIZE; 424114402Sru if (!(ch_flags & CH_CANSEEK) && pos != ch_fpos && !buffered(new_block)) 425114402Sru { 426114402Sru if (ch_fpos > pos) 427114402Sru return (1); 428114402Sru while (ch_fpos < pos) 429151497Sru { 430114402Sru if (ch_forw_get() == EOI) 431114402Sru return (1); 432114402Sru if (ABORT_SIGS()) 433114402Sru return (1); 434114402Sru } 435114402Sru return (0); 436114402Sru } 437114402Sru /* 438114402Sru * Set read pointer. 439114402Sru */ 440114402Sru ch_block = new_block; 441114402Sru ch_offset = pos % LBUFSIZE; 442114402Sru return (0); 443114402Sru} 444114402Sru 445114402Sru/* 446114402Sru * Seek to the end of the file. 447114402Sru */ 448114402Sru public int 449114402Sruch_end_seek() 450114402Sru{ 451114402Sru POSITION len; 452114402Sru 453114402Sru if (ch_flags & CH_CANSEEK) 454114402Sru ch_fsize = filesize(ch_file); 455114402Sru 456114402Sru len = ch_length(); 457114402Sru if (len != NULL_POSITION) 458114402Sru return (ch_seek(len)); 459114402Sru 460114402Sru /* 461114402Sru * Do it the slow way: read till end of data. 462114402Sru */ 463114402Sru while (ch_forw_get() != EOI) 464114402Sru if (ABORT_SIGS()) 465114402Sru return (1); 466114402Sru return (0); 467114402Sru} 468114402Sru 469114402Sru/* 470114402Sru * Seek to the beginning of the file, or as close to it as we can get. 471114402Sru * We may not be able to seek there if input is a pipe and the 472114402Sru * beginning of the pipe is no longer buffered. 473114402Sru */ 474114402Sru public int 475114402Sruch_beg_seek() 476114402Sru{ 477114402Sru register struct buf *bp, *firstbp; 478114402Sru 479114402Sru /* 480114402Sru * Try a plain ch_seek first. 481114402Sru */ 482114402Sru if (ch_seek(ch_zero()) == 0) 483114402Sru return (0); 484114402Sru 485114402Sru /* 486114402Sru * Can't get to position 0. 487114402Sru * Look thru the buffers for the one closest to position 0. 488114402Sru */ 489114402Sru firstbp = bp = ch_bufhead; 490114402Sru if (bp == END_OF_CHAIN) 491114402Sru return (1); 492114402Sru while ((bp = bp->next) != END_OF_CHAIN) 493114402Sru if (bp->block < firstbp->block) 494114402Sru firstbp = bp; 495114402Sru ch_block = firstbp->block; 496114402Sru ch_offset = 0; 497114402Sru return (0); 498114402Sru} 499114402Sru 500114402Sru/* 501114402Sru * Return the length of the file, if known. 502114402Sru */ 503114402Sru public POSITION 504114402Sruch_length() 505114402Sru{ 506114402Sru if (ignore_eoi) 507114402Sru return (NULL_POSITION); 508114402Sru if (ch_flags & CH_HELPFILE) 509114402Sru return (size_helpdata); 510114402Sru return (ch_fsize); 511114402Sru} 512114402Sru 513114402Sru/* 514114402Sru * Return the current position in the file. 515114402Sru */ 516114402Sru public POSITION 517114402Sruch_tell() 518114402Sru{ 519114402Sru return (ch_block * LBUFSIZE) + ch_offset; 520114402Sru} 521114402Sru 522114402Sru/* 523114402Sru * Get the current char and post-increment the read pointer. 524114402Sru */ 525114402Sru public int 526114402Sruch_forw_get() 527114402Sru{ 528114402Sru register int c; 529114402Sru 530114402Sru c = ch_get(); 531114402Sru if (c == EOI) 532114402Sru return (EOI); 533114402Sru if (ch_offset < LBUFSIZE-1) 534114402Sru ch_offset++; 535114402Sru else 536114402Sru { 537114402Sru ch_block ++; 538114402Sru ch_offset = 0; 539114402Sru } 540114402Sru return (c); 541114402Sru} 542114402Sru 543114402Sru/* 544114402Sru * Pre-decrement the read pointer and get the new current char. 545114402Sru */ 546114402Sru public int 547114402Sruch_back_get() 548114402Sru{ 549114402Sru if (ch_offset > 0) 550114402Sru ch_offset --; 551114402Sru else 552114402Sru { 553114402Sru if (ch_block <= 0) 554114402Sru return (EOI); 555114402Sru if (!(ch_flags & CH_CANSEEK) && !buffered(ch_block-1)) 556114402Sru return (EOI); 557114402Sru ch_block--; 558114402Sru ch_offset = LBUFSIZE-1; 559114402Sru } 560114402Sru return (ch_get()); 561114402Sru} 562114402Sru 563114402Sru/* 564114402Sru * Allocate buffers. 565114402Sru * Caller wants us to have a total of at least want_nbufs buffers. 566114402Sru */ 567114402Sru public int 568114402Sruch_nbuf(want_nbufs) 569114402Sru int want_nbufs; 570114402Sru{ 571114402Sru PARG parg; 572114402Sru 573114402Sru while (ch_nbufs < want_nbufs) 574114402Sru { 575114402Sru if (ch_addbuf()) 576114402Sru { 577114402Sru /* 578114402Sru * Cannot allocate enough buffers. 579114402Sru * If we don't have ANY, then quit. 580114402Sru * Otherwise, just report the error and return. 581114402Sru */ 582114402Sru parg.p_int = want_nbufs - ch_nbufs; 583114402Sru error("Cannot allocate %d buffers", &parg); 584114402Sru if (ch_nbufs == 0) 585114402Sru quit(QUIT_ERROR); 586114402Sru break; 587114402Sru } 588114402Sru } 589114402Sru return (ch_nbufs); 590114402Sru} 591114402Sru 592114402Sru/* 593114402Sru * Flush (discard) any saved file state, including buffer contents. 594114402Sru */ 595114402Sru public void 596114402Sruch_flush() 597114402Sru{ 598114402Sru register struct buf *bp; 599114402Sru 600114402Sru if (!(ch_flags & CH_CANSEEK)) 601114402Sru { 602114402Sru /* 603114402Sru * If input is a pipe, we don't flush buffer contents, 604114402Sru * since the contents can't be recovered. 605114402Sru */ 606114402Sru ch_fsize = NULL_POSITION; 607114402Sru return; 608114402Sru } 609114402Sru 610114402Sru /* 611114402Sru * Initialize all the buffers. 612114402Sru */ 613114402Sru for (bp = ch_bufhead; bp != END_OF_CHAIN; bp = bp->next) 614114402Sru bp->block = -1; 615114402Sru 616114402Sru /* 617114402Sru * Figure out the size of the file, if we can. 618114402Sru */ 619114402Sru ch_fsize = filesize(ch_file); 620114402Sru 621114402Sru /* 622114402Sru * Seek to a known position: the beginning of the file. 623114402Sru */ 624114402Sru ch_fpos = 0; 625114402Sru ch_block = 0; /* ch_fpos / LBUFSIZE; */ 626114402Sru ch_offset = 0; /* ch_fpos % LBUFSIZE; */ 627114402Sru 628114402Sru#if 1 629114402Sru /* 630114402Sru * This is a kludge to workaround a Linux kernel bug: files in 631114402Sru * /proc have a size of 0 according to fstat() but have readable 632114402Sru * data. They are sometimes, but not always, seekable. 633114402Sru * Force them to be non-seekable here. 634114402Sru */ 635114402Sru if (ch_fsize == 0) 636114402Sru { 637114402Sru ch_fsize = NULL_POSITION; 638114402Sru ch_flags &= ~CH_CANSEEK; 639114402Sru } 640114402Sru#endif 641 642 if (lseek(ch_file, (off_t)0, 0) == BAD_LSEEK) 643 { 644 /* 645 * Warning only; even if the seek fails for some reason, 646 * there's a good chance we're at the beginning anyway. 647 * {{ I think this is bogus reasoning. }} 648 */ 649 error("seek error to 0", NULL_PARG); 650 } 651} 652 653/* 654 * Allocate a new buffer. 655 * The buffer is added to the tail of the buffer chain. 656 */ 657 static int 658ch_addbuf() 659{ 660 register struct buf *bp; 661 662 /* 663 * Allocate and initialize a new buffer and link it 664 * onto the tail of the buffer list. 665 */ 666 bp = (struct buf *) calloc(1, sizeof(struct buf)); 667 if (bp == NULL) 668 return (1); 669 ch_nbufs++; 670 bp->block = -1; 671 bp->next = END_OF_CHAIN; 672 bp->prev = ch_buftail; 673 ch_buftail->next = bp; 674 ch_buftail = bp; 675 HASH_INS(bp, 0); 676 return (0); 677} 678 679/* 680 * 681 */ 682 static void 683init_hashtbl() 684{ 685 register int h; 686 687 for (h = 0; h < BUFHASH_SIZE; h++) 688 { 689 thisfile->hashtbl[h].buf_hnext = END_OF_HCHAIN(h); 690 thisfile->hashtbl[h].buf_hprev = END_OF_HCHAIN(h); 691 } 692} 693 694/* 695 * Delete all buffers for this file. 696 */ 697 static void 698ch_delbufs() 699{ 700 register struct buf *bp; 701 702 while (ch_bufhead != END_OF_CHAIN) 703 { 704 bp = ch_bufhead; 705 bp->next->prev = bp->prev;; 706 bp->prev->next = bp->next; 707 free(bp); 708 } 709 ch_nbufs = 0; 710 init_hashtbl(); 711} 712 713/* 714 * Is it possible to seek on a file descriptor? 715 */ 716 public int 717seekable(f) 718 int f; 719{ 720#if MSDOS_COMPILER 721 extern int fd0; 722 if (f == fd0 && !isatty(fd0)) 723 { 724 /* 725 * In MS-DOS, pipes are seekable. Check for 726 * standard input, and pretend it is not seekable. 727 */ 728 return (0); 729 } 730#endif 731 return (lseek(f, (off_t)1, 0) != BAD_LSEEK); 732} 733 734/* 735 * Initialize file state for a new file. 736 */ 737 public void 738ch_init(f, flags) 739 int f; 740 int flags; 741{ 742 /* 743 * See if we already have a filestate for this file. 744 */ 745 thisfile = (struct filestate *) get_filestate(curr_ifile); 746 if (thisfile == NULL) 747 { 748 /* 749 * Allocate and initialize a new filestate. 750 */ 751 thisfile = (struct filestate *) 752 calloc(1, sizeof(struct filestate)); 753 thisfile->buf_next = thisfile->buf_prev = END_OF_CHAIN; 754 thisfile->nbufs = 0; 755 thisfile->flags = 0; 756 thisfile->fpos = 0; 757 thisfile->block = 0; 758 thisfile->offset = 0; 759 thisfile->file = -1; 760 thisfile->fsize = NULL_POSITION; 761 ch_flags = flags; 762 init_hashtbl(); 763 /* 764 * Try to seek; set CH_CANSEEK if it works. 765 */ 766 if ((flags & CH_CANSEEK) && !seekable(f)) 767 ch_flags &= ~CH_CANSEEK; 768 set_filestate(curr_ifile, (void *) thisfile); 769 } 770 if (thisfile->file == -1) 771 thisfile->file = f; 772 ch_flush(); 773} 774 775/* 776 * Close a filestate. 777 */ 778 public void 779ch_close() 780{ 781 int keepstate = FALSE; 782 783 if (ch_flags & (CH_CANSEEK|CH_POPENED|CH_HELPFILE)) 784 { 785 /* 786 * We can seek or re-open, so we don't need to keep buffers. 787 */ 788 ch_delbufs(); 789 } else 790 keepstate = TRUE; 791 if (!(ch_flags & CH_KEEPOPEN)) 792 { 793 /* 794 * We don't need to keep the file descriptor open 795 * (because we can re-open it.) 796 * But don't really close it if it was opened via popen(), 797 * because pclose() wants to close it. 798 */ 799 if (!(ch_flags & (CH_POPENED|CH_HELPFILE))) 800 close(ch_file); 801 ch_file = -1; 802 } else 803 keepstate = TRUE; 804 if (!keepstate) 805 { 806 /* 807 * We don't even need to keep the filestate structure. 808 */ 809 free(thisfile); 810 thisfile = NULL; 811 set_filestate(curr_ifile, (void *) NULL); 812 } 813} 814 815/* 816 * Return ch_flags for the current file. 817 */ 818 public int 819ch_getflags() 820{ 821 return (ch_flags); 822} 823 824#if 0 825 public void 826ch_dump(struct filestate *fs) 827{ 828 struct buf *bp; 829 unsigned char *s; 830 831 if (fs == NULL) 832 { 833 printf(" --no filestate\n"); 834 return; 835 } 836 printf(" file %d, flags %x, fpos %x, fsize %x, blk/off %x/%x\n", 837 fs->file, fs->flags, fs->fpos, 838 fs->fsize, fs->block, fs->offset); 839 printf(" %d bufs:\n", fs->nbufs); 840 for (bp = fs->buf_next; bp != (struct buf *)fs; bp = bp->next) 841 { 842 printf("%x: blk %x, size %x \"", 843 bp, bp->block, bp->datasize); 844 for (s = bp->data; s < bp->data + 30; s++) 845 if (*s >= ' ' && *s < 0x7F) 846 printf("%c", *s); 847 else 848 printf("."); 849 printf("\"\n"); 850 } 851} 852#endif 853