contrib/less/filename.c

   1 /*
   2  * Copyright (C) 1984-2014  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  * Routines to mess around with filenames (and files).
  13  * Much of this is very OS dependent.
  14  */
  15
  16 #include "less.h"
  17 #include "lglob.h"
  18 #if MSDOS_COMPILER
  19 #include <dos.h>
  20 #if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER)
  21 #include <dir.h>
  22 #endif
  23 #if MSDOS_COMPILER==DJGPPC
  24 #include <glob.h>
  25 #include <dir.h>
  26 #define _MAX_PATH       PATH_MAX
  27 #endif
  28 #endif
  29 #ifdef _OSK
  30 #include <rbf.h>
  31 #ifndef _OSK_MWC32
  32 #include <modes.h>
  33 #endif
  34 #endif
  35 #if OS2
  36 #include <signal.h>
  37 #endif
  38
  39 #if HAVE_STAT
  40 #include <sys/stat.h>
  41 #ifndef S_ISDIR
  42 #define S_ISDIR(m)      (((m) & S_IFMT) == S_IFDIR)
  43 #endif
  44 #ifndef S_ISREG
  45 #define S_ISREG(m)      (((m) & S_IFMT) == S_IFREG)
  46 #endif
  47 #endif
  48
  49
  50 extern int force_open;
  51 extern int secure;
  52 extern int use_lessopen;
  53 extern int ctldisp;
  54 extern int utf_mode;
  55 extern IFILE curr_ifile;
  56 extern IFILE old_ifile;
  57 #if SPACES_IN_FILENAMES
  58 extern char openquote;
  59 extern char closequote;
  60 #endif
  61
  62 /*
  63  * Remove quotes around a filename.
  64  */
  65         public char *
  66 shell_unquote(str)
  67         char *str;
  68 {
  69         char *name;
  70         char *p;
  71
  72         name = p = (char *) ecalloc(strlen(str)+1, sizeof(char));
  73         if (*str == openquote)
  74         {
  75                 str++;
  76                 while (*str != '\0')
  77                 {
  78                         if (*str == closequote)
  79                         {
  80                                 if (str[1] != closequote)
  81                                         break;
  82                                 str++;
  83                         }
  84                         *p++ = *str++;
  85                 }
  86         } else
  87         {
  88                 char *esc = get_meta_escape();
  89                 int esclen = (int) strlen(esc);
  90                 while (*str != '\0')
  91                 {
  92                         if (esclen > 0 && strncmp(str, esc, esclen) == 0)
  93                                 str += esclen;
  94                         *p++ = *str++;
  95                 }
  96         }
  97         *p = '\0';
  98         return (name);
  99 }
 100
 101 /*
 102  * Get the shell's escape character.
 103  */
 104         public char *
 105 get_meta_escape()
 106 {
 107         char *s;
 108
 109         s = lgetenv("LESSMETAESCAPE");
 110         if (s == NULL)
 111                 s = DEF_METAESCAPE;
 112         return (s);
 113 }
 114
 115 /*
 116  * Get the characters which the shell considers to be "metacharacters".
 117  */
 118         static char *
 119 metachars()
 120 {
 121         static char *mchars = NULL;
 122
 123         if (mchars == NULL)
 124         {
 125                 mchars = lgetenv("LESSMETACHARS");
 126                 if (mchars == NULL)
 127                         mchars = DEF_METACHARS;
 128         }
 129         return (mchars);
 130 }
 131
 132 /*
 133  * Is this a shell metacharacter?
 134  */
 135         static int
 136 metachar(c)
 137         char c;
 138 {
 139         return (strchr(metachars(), c) != NULL);
 140 }
 141
 142 /*
 143  * Insert a backslash before each metacharacter in a string.
 144  */
 145         public char *
 146 shell_quote(s)
 147         char *s;
 148 {
 149         char *p;
 150         char *newstr;
 151         int len;
 152         char *esc = get_meta_escape();
 153         int esclen = (int) strlen(esc);
 154         int use_quotes = 0;
 155         int have_quotes = 0;
 156
 157         /*
 158          * Determine how big a string we need to allocate.
 159          */
 160         len = 1; /* Trailing null byte */
 161         for (p = s;  *p != '\0';  p++)
 162         {
 163                 len++;
 164                 if (*p == openquote || *p == closequote)
 165                         have_quotes = 1;
 166                 if (metachar(*p))
 167                 {
 168                         if (esclen == 0)
 169                         {
 170                                 /*
 171                                  * We've got a metachar, but this shell
 172                                  * doesn't support escape chars.  Use quotes.
 173                                  */
 174                                 use_quotes = 1;
 175                         } else
 176                         {
 177                                 /*
 178                                  * Allow space for the escape char.
 179                                  */
 180                                 len += esclen;
 181                         }
 182                 }
 183         }
 184         if (use_quotes)
 185         {
 186                 if (have_quotes)
 187                         /*
 188                          * We can't quote a string that contains quotes.
 189                          */
 190                         return (NULL);
 191                 len = (int) strlen(s) + 3;
 192         }
 193         /*
 194          * Allocate and construct the new string.
 195          */
 196         newstr = p = (char *) ecalloc(len, sizeof(char));
 197         if (use_quotes)
 198         {
 199                 SNPRINTF3(newstr, len, "%c%s%c", openquote, s, closequote);
 200         } else
 201         {
 202                 while (*s != '\0')
 203                 {
 204                         if (metachar(*s))
 205                         {
 206                                 /*
 207                                  * Add the escape char.
 208                                  */
 209                                 strcpy(p, esc);
 210                                 p += esclen;
 211                         }
 212                         *p++ = *s++;
 213                 }
 214                 *p = '\0';
 215         }
 216         return (newstr);
 217 }
 218
 219 /*
 220  * Return a pathname that points to a specified file in a specified directory.
 221  * Return NULL if the file does not exist in the directory.
 222  */
 223         static char *
 224 dirfile(dirname, filename)
 225         char *dirname;
 226         char *filename;
 227 {
 228         char *pathname;
 229         char *qpathname;
 230         int len;
 231         int f;
 232
 233         if (dirname == NULL || *dirname == '\0')
 234                 return (NULL);
 235         /*
 236          * Construct the full pathname.
 237          */
 238         len = (int) (strlen(dirname) + strlen(filename) + 2);
 239         pathname = (char *) calloc(len, sizeof(char));
 240         if (pathname == NULL)
 241                 return (NULL);
 242         SNPRINTF3(pathname, len, "%s%s%s", dirname, PATHNAME_SEP, filename);
 243         /*
 244          * Make sure the file exists.
 245          */
 246         qpathname = shell_unquote(pathname);
 247         f = open(qpathname, OPEN_READ);
 248         if (f < 0)
 249         {
 250                 free(pathname);
 251                 pathname = NULL;
 252         } else
 253         {
 254                 close(f);
 255         }
 256         free(qpathname);
 257         return (pathname);
 258 }
 259
 260 /*
 261  * Return the full pathname of the given file in the "home directory".
 262  */
 263         public char *
 264 homefile(filename)
 265         char *filename;
 266 {
 267         register char *pathname;
 268
 269         /*
 270          * Try $HOME/filename.
 271          */
 272         pathname = dirfile(lgetenv("HOME"), filename);
 273         if (pathname != NULL)
 274                 return (pathname);
 275 #if OS2
 276         /*
 277          * Try $INIT/filename.
 278          */
 279         pathname = dirfile(lgetenv("INIT"), filename);
 280         if (pathname != NULL)
 281                 return (pathname);
 282 #endif
 283 #if MSDOS_COMPILER || OS2
 284         /*
 285          * Look for the file anywhere on search path.
 286          */
 287         pathname = (char *) calloc(_MAX_PATH, sizeof(char));
 288 #if MSDOS_COMPILER==DJGPPC
 289         {
 290                 char *res = searchpath(filename);
 291                 if (res == 0)
 292                         *pathname = '\0';
 293                 else
 294                         strcpy(pathname, res);
 295         }
 296 #else
 297         _searchenv(filename, "PATH", pathname);
 298 #endif
 299         if (*pathname != '\0')
 300                 return (pathname);
 301         free(pathname);
 302 #endif
 303         return (NULL);
 304 }
 305
 306 /*
 307  * Expand a string, substituting any "%" with the current filename,
 308  * and any "#" with the previous filename.
 309  * But a string of N "%"s is just replaced with N-1 "%"s.
 310  * Likewise for a string of N "#"s.
 311  * {{ This is a lot of work just to support % and #. }}
 312  */
 313         public char *
 314 fexpand(s)
 315         char *s;
 316 {
 317         register char *fr, *to;
 318         register int n;
 319         register char *e;
 320         IFILE ifile;
 321
 322 #define fchar_ifile(c) \
 323         ((c) == '%' ? curr_ifile : \
 324          (c) == '#' ? old_ifile : NULL_IFILE)
 325
 326         /*
 327          * Make one pass to see how big a buffer we
 328          * need to allocate for the expanded string.
 329          */
 330         n = 0;
 331         for (fr = s;  *fr != '\0';  fr++)
 332         {
 333                 switch (*fr)
 334                 {
 335                 case '%':
 336                 case '#':
 337                         if (fr > s && fr[-1] == *fr)
 338                         {
 339                                 /*
 340                                  * Second (or later) char in a string
 341                                  * of identical chars.  Treat as normal.
 342                                  */
 343                                 n++;
 344                         } else if (fr[1] != *fr)
 345                         {
 346                                 /*
 347                                  * Single char (not repeated).  Treat specially.
 348                                  */
 349                                 ifile = fchar_ifile(*fr);
 350                                 if (ifile == NULL_IFILE)
 351                                         n++;
 352                                 else
 353                                         n += (int) strlen(get_filename(ifile));
 354                         }
 355                         /*
 356                          * Else it is the first char in a string of
 357                          * identical chars.  Just discard it.
 358                          */
 359                         break;
 360                 default:
 361                         n++;
 362                         break;
 363                 }
 364         }
 365
 366         e = (char *) ecalloc(n+1, sizeof(char));
 367
 368         /*
 369          * Now copy the string, expanding any "%" or "#".
 370          */
 371         to = e;
 372         for (fr = s;  *fr != '\0';  fr++)
 373         {
 374                 switch (*fr)
 375                 {
 376                 case '%':
 377                 case '#':
 378                         if (fr > s && fr[-1] == *fr)
 379                         {
 380                                 *to++ = *fr;
 381                         } else if (fr[1] != *fr)
 382                         {
 383                                 ifile = fchar_ifile(*fr);
 384                                 if (ifile == NULL_IFILE)
 385                                         *to++ = *fr;
 386                                 else
 387                                 {
 388                                         strcpy(to, get_filename(ifile));
 389                                         to += strlen(to);
 390                                 }
 391                         }
 392                         break;
 393                 default:
 394                         *to++ = *fr;
 395                         break;
 396                 }
 397         }
 398         *to = '\0';
 399         return (e);
 400 }
 401
 402
 403 #if TAB_COMPLETE_FILENAME
 404
 405 /*
 406  * Return a blank-separated list of filenames which "complete"
 407  * the given string.
 408  */
 409         public char *
 410 fcomplete(s)
 411         char *s;
 412 {
 413         char *fpat;
 414         char *qs;
 415
 416         if (secure)
 417                 return (NULL);
 418         /*
 419          * Complete the filename "s" by globbing "s*".
 420          */
 421 #if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
 422         /*
 423          * But in DOS, we have to glob "s*.*".
 424          * But if the final component of the filename already has
 425          * a dot in it, just do "s*".
 426          * (Thus, "FILE" is globbed as "FILE*.*",
 427          *  but "FILE.A" is globbed as "FILE.A*").
 428          */
 429         {
 430                 char *slash;
 431                 int len;
 432                 for (slash = s+strlen(s)-1;  slash > s;  slash--)
 433                         if (*slash == *PATHNAME_SEP || *slash == '/')
 434                                 break;
 435                 len = (int) strlen(s) + 4;
 436                 fpat = (char *) ecalloc(len, sizeof(char));
 437                 if (strchr(slash, '.') == NULL)
 438                         SNPRINTF1(fpat, len, "%s*.*", s);
 439                 else
 440                         SNPRINTF1(fpat, len, "%s*", s);
 441         }
 442 #else
 443         {
 444         int len = (int) strlen(s) + 2;
 445         fpat = (char *) ecalloc(len, sizeof(char));
 446         SNPRINTF1(fpat, len, "%s*", s);
 447         }
 448 #endif
 449         qs = lglob(fpat);
 450         s = shell_unquote(qs);
 451         if (strcmp(s,fpat) == 0)
 452         {
 453                 /*
 454                  * The filename didn't expand.
 455                  */
 456                 free(qs);
 457                 qs = NULL;
 458         }
 459         free(s);
 460         free(fpat);
 461         return (qs);
 462 }
 463 #endif
 464
 465 /*
 466  * Try to determine if a file is "binary".
 467  * This is just a guess, and we need not try too hard to make it accurate.
 468  */
 469         public int
 470 bin_file(f)
 471         int f;
 472 {
 473         int n;
 474         int bin_count = 0;
 475         char data[256];
 476         char* p;
 477         char* pend;
 478
 479         if (!seekable(f))
 480                 return (0);
 481         if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
 482                 return (0);
 483         n = read(f, data, sizeof(data));
 484         if (n <= 0)
 485                 return (0);
 486         if (utf_mode)
 487         {
 488                 bin_count = utf_bin_count(data, n);
 489         } else
 490         {
 491                 pend = &data[n];
 492                 for (p = data;  p < pend;  )
 493                 {
 494                         LWCHAR c = step_char(&p, +1, pend);
 495                         if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
 496                         {
 497                                 do {
 498                                         c = step_char(&p, +1, pend);
 499                                 } while (p < pend && is_ansi_middle(c));
 500                         } else if (binary_char(c))
 501                                 bin_count++;
 502                 }
 503         }
 504         /*
 505          * Call it a binary file if there are more than 5 binary characters
 506          * in the first 256 bytes of the file.
 507          */
 508         return (bin_count > 5);
 509 }
 510
 511 /*
 512  * Try to determine the size of a file by seeking to the end.
 513  */
 514         static POSITION
 515 seek_filesize(f)
 516         int f;
 517 {
 518         off_t spos;
 519
 520         spos = lseek(f, (off_t)0, SEEK_END);
 521         if (spos == BAD_LSEEK)
 522                 return (NULL_POSITION);
 523         return ((POSITION) spos);
 524 }
 525
 526 /*
 527  * Read a string from a file.
 528  * Return a pointer to the string in memory.
 529  */
 530         static char *
 531 readfd(fd)
 532         FILE *fd;
 533 {
 534         int len;
 535         int ch;
 536         char *buf;
 537         char *p;
 538
 539         /*
 540          * Make a guess about how many chars in the string
 541          * and allocate a buffer to hold it.
 542          */
 543         len = 100;
 544         buf = (char *) ecalloc(len, sizeof(char));
 545         for (p = buf;  ;  p++)
 546         {
 547                 if ((ch = getc(fd)) == '\n' || ch == EOF)
 548                         break;
 549                 if (p - buf >= len-1)
 550                 {
 551                         /*
 552                          * The string is too big to fit in the buffer we have.
 553                          * Allocate a new buffer, twice as big.
 554                          */
 555                         len *= 2;
 556                         *p = '\0';
 557                         p = (char *) ecalloc(len, sizeof(char));
 558                         strcpy(p, buf);
 559                         free(buf);
 560                         buf = p;
 561                         p = buf + strlen(buf);
 562                 }
 563                 *p = ch;
 564         }
 565         *p = '\0';
 566         return (buf);
 567 }
 568
 569
 570
 571 #if HAVE_POPEN
 572
 573 FILE *popen();
 574
 575 /*
 576  * Execute a shell command.
 577  * Return a pointer to a pipe connected to the shell command's standard output.
 578  */
 579         static FILE *
 580 shellcmd(cmd)
 581         char *cmd;
 582 {
 583         FILE *fd;
 584
 585 #if HAVE_SHELL
 586         char *shell;
 587
 588         shell = lgetenv("SHELL");
 589         if (shell != NULL && *shell != '\0')
 590         {
 591                 char *scmd;
 592                 char *esccmd;
 593
 594                 /*
 595                  * Read the output of <$SHELL -c cmd>.
 596                  * Escape any metacharacters in the command.
 597                  */
 598                 esccmd = shell_quote(cmd);
 599                 if (esccmd == NULL)
 600                 {
 601                         fd = popen(cmd, "r");
 602                 } else
 603                 {
 604                         int len = (int) (strlen(shell) + strlen(esccmd) + 5);
 605                         scmd = (char *) ecalloc(len, sizeof(char));
 606                         SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
 607                         free(esccmd);
 608                         fd = popen(scmd, "r");
 609                         free(scmd);
 610                 }
 611         } else
 612 #endif
 613         {
 614                 fd = popen(cmd, "r");
 615         }
 616         /*
 617          * Redirection in `popen' might have messed with the
 618          * standard devices.  Restore binary input mode.
 619          */
 620         SET_BINARY(0);
 621         return (fd);
 622 }
 623
 624 #endif /* HAVE_POPEN */
 625
 626
 627 /*
 628  * Expand a filename, doing any system-specific metacharacter substitutions.
 629  */
 630         public char *
 631 lglob(filename)
 632         char *filename;
 633 {
 634         char *gfilename;
 635         char *ofilename;
 636
 637         ofilename = fexpand(filename);
 638         if (secure)
 639                 return (ofilename);
 640         filename = shell_unquote(ofilename);
 641
 642 #ifdef DECL_GLOB_LIST
 643 {
 644         /*
 645          * The globbing function returns a list of names.
 646          */
 647         int length;
 648         char *p;
 649         char *qfilename;
 650         DECL_GLOB_LIST(list)
 651
 652         GLOB_LIST(filename, list);
 653         if (GLOB_LIST_FAILED(list))
 654         {
 655                 free(filename);
 656                 return (ofilename);
 657         }
 658         length = 1; /* Room for trailing null byte */
 659         for (SCAN_GLOB_LIST(list, p))
 660         {
 661                 INIT_GLOB_LIST(list, p);
 662                 qfilename = shell_quote(p);
 663                 if (qfilename != NULL)
 664                 {
 665                         length += strlen(qfilename) + 1;
 666                         free(qfilename);
 667                 }
 668         }
 669         gfilename = (char *) ecalloc(length, sizeof(char));
 670         for (SCAN_GLOB_LIST(list, p))
 671         {
 672                 INIT_GLOB_LIST(list, p);
 673                 qfilename = shell_quote(p);
 674                 if (qfilename != NULL)
 675                 {
 676                         sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
 677                         free(qfilename);
 678                 }
 679         }
 680         /*
 681          * Overwrite the final trailing space with a null terminator.
 682          */
 683         *--p = '\0';
 684         GLOB_LIST_DONE(list);
 685 }
 686 #else
 687 #ifdef DECL_GLOB_NAME
 688 {
 689         /*
 690          * The globbing function returns a single name, and
 691          * is called multiple times to walk thru all names.
 692          */
 693         register char *p;
 694         register int len;
 695         register int n;
 696         char *pathname;
 697         char *qpathname;
 698         DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
 699
 700         GLOB_FIRST_NAME(filename, &fnd, handle);
 701         if (GLOB_FIRST_FAILED(handle))
 702         {
 703                 free(filename);
 704                 return (ofilename);
 705         }
 706
 707         _splitpath(filename, drive, dir, fname, ext);
 708         len = 100;
 709         gfilename = (char *) ecalloc(len, sizeof(char));
 710         p = gfilename;
 711         do {
 712                 n = (int) (strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1);
 713                 pathname = (char *) ecalloc(n, sizeof(char));
 714                 SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
 715                 qpathname = shell_quote(pathname);
 716                 free(pathname);
 717                 if (qpathname != NULL)
 718                 {
 719                         n = (int) strlen(qpathname);
 720                         while (p - gfilename + n + 2 >= len)
 721                         {
 722                                 /*
 723                                  * No room in current buffer.
 724                                  * Allocate a bigger one.
 725                                  */
 726                                 len *= 2;
 727                                 *p = '\0';
 728                                 p = (char *) ecalloc(len, sizeof(char));
 729                                 strcpy(p, gfilename);
 730                                 free(gfilename);
 731                                 gfilename = p;
 732                                 p = gfilename + strlen(gfilename);
 733                         }
 734                         strcpy(p, qpathname);
 735                         free(qpathname);
 736                         p += n;
 737                         *p++ = ' ';
 738                 }
 739         } while (GLOB_NEXT_NAME(handle, &fnd) == 0);
 740
 741         /*
 742          * Overwrite the final trailing space with a null terminator.
 743          */
 744         *--p = '\0';
 745         GLOB_NAME_DONE(handle);
 746 }
 747 #else
 748 #if HAVE_POPEN
 749 {
 750         /*
 751          * We get the shell to glob the filename for us by passing
 752          * an "echo" command to the shell and reading its output.
 753          */
 754         FILE *fd;
 755         char *s;
 756         char *lessecho;
 757         char *cmd;
 758         char *esc;
 759         int len;
 760
 761         esc = get_meta_escape();
 762         if (strlen(esc) == 0)
 763                 esc = "-";
 764         esc = shell_quote(esc);
 765         if (esc == NULL)
 766         {
 767                 free(filename);
 768                 return (ofilename);
 769         }
 770         lessecho = lgetenv("LESSECHO");
 771         if (lessecho == NULL || *lessecho == '\0')
 772                 lessecho = "lessecho";
 773         /*
 774          * Invoke lessecho, and read its output (a globbed list of filenames).
 775          */
 776         len = (int) (strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24);
 777         cmd = (char *) ecalloc(len, sizeof(char));
 778         SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
 779         free(esc);
 780         for (s = metachars();  *s != '\0';  s++)
 781                 sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
 782         sprintf(cmd + strlen(cmd), "-- %s", ofilename);
 783         fd = shellcmd(cmd);
 784         free(cmd);
 785         if (fd == NULL)
 786         {
 787                 /*
 788                  * Cannot create the pipe.
 789                  * Just return the original (fexpanded) filename.
 790                  */
 791                 free(filename);
 792                 return (ofilename);
 793         }
 794         gfilename = readfd(fd);
 795         pclose(fd);
 796         if (*gfilename == '\0')
 797         {
 798                 free(gfilename);
 799                 free(filename);
 800                 return (ofilename);
 801         }
 802 }
 803 #else
 804         /*
 805          * No globbing functions at all.  Just use the fexpanded filename.
 806          */
 807         gfilename = save(filename);
 808 #endif
 809 #endif
 810 #endif
 811         free(filename);
 812         free(ofilename);
 813         return (gfilename);
 814 }
 815
 816 /*
 817  * Return number of %s escapes in a string.
 818  * Return a large number if there are any other % escapes besides %s.
 819  */
 820         static int
 821 num_pct_s(lessopen)
 822         char *lessopen;
 823 {
 824         int num;
 825
 826         for (num = 0;; num++)
 827         {
 828                 lessopen = strchr(lessopen, '%');
 829                 if (lessopen == NULL)
 830                         break;
 831                 if (*++lessopen != 's')
 832                         return (999);
 833         }
 834         return (num);
 835 }
 836
 837 /*
 838  * See if we should open a "replacement file"
 839  * instead of the file we're about to open.
 840  */
 841         public char *
 842 open_altfile(filename, pf, pfd)
 843         char *filename;
 844         int *pf;
 845         void **pfd;
 846 {
 847 #if !HAVE_POPEN
 848         return (NULL);
 849 #else
 850         char *lessopen;
 851         char *cmd;
 852         int len;
 853         FILE *fd;
 854 #if HAVE_FILENO
 855         int returnfd = 0;
 856 #endif
 857
 858         if (!use_lessopen || secure)
 859                 return (NULL);
 860         ch_ungetchar(-1);
 861         if ((lessopen = lgetenv("LESSOPEN")) == NULL)
 862                 return (NULL);
 863         while (*lessopen == '|')
 864         {
 865                 /*
 866                  * If LESSOPEN starts with a |, it indicates
 867                  * a "pipe preprocessor".
 868                  */
 869 #if !HAVE_FILENO
 870                 error("LESSOPEN pipe is not supported", NULL_PARG);
 871                 return (NULL);
 872 #else
 873                 lessopen++;
 874                 returnfd++;
 875 #endif
 876         }
 877         if (*lessopen == '-') {
 878                 /*
 879                  * Lessopen preprocessor will accept "-" as a filename.
 880                  */
 881                 lessopen++;
 882         } else {
 883                 if (strcmp(filename, "-") == 0)
 884                         return (NULL);
 885         }
 886         if (num_pct_s(lessopen) > 1)
 887         {
 888                 error("Invalid LESSOPEN variable", NULL_PARG);
 889                 return (NULL);
 890         }
 891
 892         len = (int) (strlen(lessopen) + strlen(filename) + 2);
 893         cmd = (char *) ecalloc(len, sizeof(char));
 894         SNPRINTF1(cmd, len, lessopen, filename);
 895         fd = shellcmd(cmd);
 896         free(cmd);
 897         if (fd == NULL)
 898         {
 899                 /*
 900                  * Cannot create the pipe.
 901                  */
 902                 return (NULL);
 903         }
 904 #if HAVE_FILENO
 905         if (returnfd)
 906         {
 907                 int f;
 908                 char c;
 909
 910                 /*
 911                  * Read one char to see if the pipe will produce any data.
 912                  * If it does, push the char back on the pipe.
 913                  */
 914                 f = fileno(fd);
 915                 SET_BINARY(f);
 916                 if (read(f, &c, 1) != 1)
 917                 {
 918                         /*
 919                          * Pipe is empty.
 920                          * If more than 1 pipe char was specified,
 921                          * the exit status tells whether the file itself
 922                          * is empty, or if there is no alt file.
 923                          * If only one pipe char, just assume no alt file.
 924                          */
 925                         int status = pclose(fd);
 926                         if (returnfd > 1 && status == 0) {
 927                                 *pfd = NULL;
 928                                 *pf = -1;
 929                                 return (save(FAKE_EMPTYFILE));
 930                         }
 931                         return (NULL);
 932                 }
 933                 ch_ungetchar(c);
 934                 *pfd = (void *) fd;
 935                 *pf = f;
 936                 return (save("-"));
 937         }
 938 #endif
 939         cmd = readfd(fd);
 940         pclose(fd);
 941         if (*cmd == '\0')
 942                 /*
 943                  * Pipe is empty.  This means there is no alt file.
 944                  */
 945                 return (NULL);
 946         return (cmd);
 947 #endif /* HAVE_POPEN */
 948 }
 949
 950 /*
 951  * Close a replacement file.
 952  */
 953         public void
 954 close_altfile(altfilename, filename, pipefd)
 955         char *altfilename;
 956         char *filename;
 957         void *pipefd;
 958 {
 959 #if HAVE_POPEN
 960         char *lessclose;
 961         FILE *fd;
 962         char *cmd;
 963         int len;
 964
 965         if (secure)
 966                 return;
 967         if (pipefd != NULL)
 968         {
 969 #if OS2
 970                 /*
 971                  * The pclose function of OS/2 emx sometimes fails.
 972                  * Send SIGINT to the piped process before closing it.
 973                  */
 974                 kill(((FILE*)pipefd)->_pid, SIGINT);
 975 #endif
 976                 pclose((FILE*) pipefd);
 977         }
 978         if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
 979                 return;
 980         if (num_pct_s(lessclose) > 2)
 981         {
 982                 error("Invalid LESSCLOSE variable");
 983                 return;
 984         }
 985         len = (int) (strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2);
 986         cmd = (char *) ecalloc(len, sizeof(char));
 987         SNPRINTF2(cmd, len, lessclose, filename, altfilename);
 988         fd = shellcmd(cmd);
 989         free(cmd);
 990         if (fd != NULL)
 991                 pclose(fd);
 992 #endif
 993 }
 994
 995 /*
 996  * Is the specified file a directory?
 997  */
 998         public int
 999 is_dir(filename)
1000         char *filename;
1001 {
1002         int isdir = 0;
1003
1004         filename = shell_unquote(filename);
1005 #if HAVE_STAT
1006 {
1007         int r;
1008         struct stat statbuf;
1009
1010         r = stat(filename, &statbuf);
1011         isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
1012 }
1013 #else
1014 #ifdef _OSK
1015 {
1016         register int f;
1017
1018         f = open(filename, S_IREAD | S_IFDIR);
1019         if (f >= 0)
1020                 close(f);
1021         isdir = (f >= 0);
1022 }
1023 #endif
1024 #endif
1025         free(filename);
1026         return (isdir);
1027 }
1028
1029 /*
1030  * Returns NULL if the file can be opened and
1031  * is an ordinary file, otherwise an error message
1032  * (if it cannot be opened or is a directory, etc.)
1033  */
1034         public char *
1035 bad_file(filename)
1036         char *filename;
1037 {
1038         register char *m = NULL;
1039
1040         filename = shell_unquote(filename);
1041         if (!force_open && is_dir(filename))
1042         {
1043                 static char is_a_dir[] = " is a directory";
1044
1045                 m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
1046                         sizeof(char));
1047                 strcpy(m, filename);
1048                 strcat(m, is_a_dir);
1049         } else
1050         {
1051 #if HAVE_STAT
1052                 int r;
1053                 struct stat statbuf;
1054
1055                 r = stat(filename, &statbuf);
1056                 if (r < 0)
1057                 {
1058                         m = errno_message(filename);
1059                 } else if (force_open)
1060                 {
1061                         m = NULL;
1062                 } else if (!S_ISREG(statbuf.st_mode))
1063                 {
1064                         static char not_reg[] = " is not a regular file (use -f to see it)";
1065                         m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1066                                 sizeof(char));
1067                         strcpy(m, filename);
1068                         strcat(m, not_reg);
1069                 }
1070 #endif
1071         }
1072         free(filename);
1073         return (m);
1074 }
1075
1076 /*
1077  * Return the size of a file, as cheaply as possible.
1078  * In Unix, we can stat the file.
1079  */
1080         public POSITION
1081 filesize(f)
1082         int f;
1083 {
1084 #if HAVE_STAT
1085         struct stat statbuf;
1086
1087         if (fstat(f, &statbuf) >= 0)
1088                 return ((POSITION) statbuf.st_size);
1089 #else
1090 #ifdef _OSK
1091         long size;
1092
1093         if ((size = (long) _gs_size(f)) >= 0)
1094                 return ((POSITION) size);
1095 #endif
1096 #endif
1097         return (seek_filesize(f));
1098 }
1099
1100 /*
1101  *
1102  */
1103         public char *
1104 shell_coption()
1105 {
1106         return ("-c");
1107 }
1108
1109 /*
1110  * Return last component of a pathname.
1111  */
1112         public char *
1113 last_component(name)
1114         char *name;
1115 {
1116         char *slash;
1117
1118         for (slash = name + strlen(name);  slash > name; )
1119         {
1120                 --slash;
1121                 if (*slash == *PATHNAME_SEP || *slash == '/')
1122                         return (slash + 1);
1123         }
1124         return (name);
1125 }
1126