contrib/less/filename.c

   1 /*
   2  * Copyright (C) 1984-2008  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 about less, or for information on how to
   8  * contact the author, see the README file.
   9  */
  10
  11
  12 /*
  13  * Routines to mess around with filenames (and files).
  14  * Much of this is very OS dependent.
  15  */
  16
  17 #include "less.h"
  18 #include "lglob.h"
  19 #if MSDOS_COMPILER
  20 #include <dos.h>
  21 #if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER)
  22 #include <dir.h>
  23 #endif
  24 #if MSDOS_COMPILER==DJGPPC
  25 #include <glob.h>
  26 #include <dir.h>
  27 #define _MAX_PATH       PATH_MAX
  28 #endif
  29 #endif
  30 #ifdef _OSK
  31 #include <rbf.h>
  32 #ifndef _OSK_MWC32
  33 #include <modes.h>
  34 #endif
  35 #endif
  36 #if OS2
  37 #include <signal.h>
  38 #endif
  39
  40 #if HAVE_STAT
  41 #include <sys/stat.h>
  42 #ifndef S_ISDIR
  43 #define S_ISDIR(m)      (((m) & S_IFMT) == S_IFDIR)
  44 #endif
  45 #ifndef S_ISREG
  46 #define S_ISREG(m)      (((m) & S_IFMT) == S_IFREG)
  47 #endif
  48 #endif
  49
  50
  51 extern int force_open;
  52 extern int secure;
  53 extern int use_lessopen;
  54 extern int ctldisp;
  55 extern int utf_mode;
  56 extern IFILE curr_ifile;
  57 extern IFILE old_ifile;
  58 #if SPACES_IN_FILENAMES
  59 extern char openquote;
  60 extern char closequote;
  61 #endif
  62
  63 /*
  64  * Remove quotes around a filename.
  65  */
  66         public char *
  67 shell_unquote(str)
  68         char *str;
  69 {
  70         char *name;
  71         char *p;
  72
  73         name = p = (char *) ecalloc(strlen(str)+1, sizeof(char));
  74         if (*str == openquote)
  75         {
  76                 str++;
  77                 while (*str != '\0')
  78                 {
  79                         if (*str == closequote)
  80                         {
  81                                 if (str[1] != closequote)
  82                                         break;
  83                                 str++;
  84                         }
  85                         *p++ = *str++;
  86                 }
  87         } else
  88         {
  89                 char *esc = get_meta_escape();
  90                 int esclen = strlen(esc);
  91                 while (*str != '\0')
  92                 {
  93                         if (esclen > 0 && strncmp(str, esc, esclen) == 0)
  94                                 str += esclen;
  95                         *p++ = *str++;
  96                 }
  97         }
  98         *p = '\0';
  99         return (name);
 100 }
 101
 102 /*
 103  * Get the shell's escape character.
 104  */
 105         public char *
 106 get_meta_escape()
 107 {
 108         char *s;
 109
 110         s = lgetenv("LESSMETAESCAPE");
 111         if (s == NULL)
 112                 s = DEF_METAESCAPE;
 113         return (s);
 114 }
 115
 116 /*
 117  * Get the characters which the shell considers to be "metacharacters".
 118  */
 119         static char *
 120 metachars()
 121 {
 122         static char *mchars = NULL;
 123
 124         if (mchars == NULL)
 125         {
 126                 mchars = lgetenv("LESSMETACHARS");
 127                 if (mchars == NULL)
 128                         mchars = DEF_METACHARS;
 129         }
 130         return (mchars);
 131 }
 132
 133 /*
 134  * Is this a shell metacharacter?
 135  */
 136         static int
 137 metachar(c)
 138         char c;
 139 {
 140         return (strchr(metachars(), c) != NULL);
 141 }
 142
 143 /*
 144  * Insert a backslash before each metacharacter in a string.
 145  */
 146         public char *
 147 shell_quote(s)
 148         char *s;
 149 {
 150         char *p;
 151         char *newstr;
 152         int len;
 153         char *esc = get_meta_escape();
 154         int esclen = strlen(esc);
 155         int use_quotes = 0;
 156         int have_quotes = 0;
 157
 158         /*
 159          * Determine how big a string we need to allocate.
 160          */
 161         len = 1; /* Trailing null byte */
 162         for (p = s;  *p != '\0';  p++)
 163         {
 164                 len++;
 165                 if (*p == openquote || *p == closequote)
 166                         have_quotes = 1;
 167                 if (metachar(*p))
 168                 {
 169                         if (esclen == 0)
 170                         {
 171                                 /*
 172                                  * We've got a metachar, but this shell
 173                                  * doesn't support escape chars.  Use quotes.
 174                                  */
 175                                 use_quotes = 1;
 176                         } else
 177                         {
 178                                 /*
 179                                  * Allow space for the escape char.
 180                                  */
 181                                 len += esclen;
 182                         }
 183                 }
 184         }
 185         if (use_quotes)
 186         {
 187                 if (have_quotes)
 188                         /*
 189                          * We can't quote a string that contains quotes.
 190                          */
 191                         return (NULL);
 192                 len = strlen(s) + 3;
 193         }
 194         /*
 195          * Allocate and construct the new string.
 196          */
 197         newstr = p = (char *) ecalloc(len, sizeof(char));
 198         if (use_quotes)
 199         {
 200                 SNPRINTF3(newstr, len, "%c%s%c", openquote, s, closequote);
 201         } else
 202         {
 203                 while (*s != '\0')
 204                 {
 205                         if (metachar(*s))
 206                         {
 207                                 /*
 208                                  * Add the escape char.
 209                                  */
 210                                 strcpy(p, esc);
 211                                 p += esclen;
 212                         }
 213                         *p++ = *s++;
 214                 }
 215                 *p = '\0';
 216         }
 217         return (newstr);
 218 }
 219
 220 /*
 221  * Return a pathname that points to a specified file in a specified directory.
 222  * Return NULL if the file does not exist in the directory.
 223  */
 224         static char *
 225 dirfile(dirname, filename)
 226         char *dirname;
 227         char *filename;
 228 {
 229         char *pathname;
 230         char *qpathname;
 231         int len;
 232         int f;
 233
 234         if (dirname == NULL || *dirname == '\0')
 235                 return (NULL);
 236         /*
 237          * Construct the full pathname.
 238          */
 239         len= strlen(dirname) + strlen(filename) + 2;
 240         pathname = (char *) calloc(len, sizeof(char));
 241         if (pathname == NULL)
 242                 return (NULL);
 243         SNPRINTF3(pathname, len, "%s%s%s", dirname, PATHNAME_SEP, filename);
 244         /*
 245          * Make sure the file exists.
 246          */
 247         qpathname = shell_unquote(pathname);
 248         f = open(qpathname, OPEN_READ);
 249         if (f < 0)
 250         {
 251                 free(pathname);
 252                 pathname = NULL;
 253         } else
 254         {
 255                 close(f);
 256         }
 257         free(qpathname);
 258         return (pathname);
 259 }
 260
 261 /*
 262  * Return the full pathname of the given file in the "home directory".
 263  */
 264         public char *
 265 homefile(filename)
 266         char *filename;
 267 {
 268         register char *pathname;
 269
 270         /*
 271          * Try $HOME/filename.
 272          */
 273         pathname = dirfile(lgetenv("HOME"), filename);
 274         if (pathname != NULL)
 275                 return (pathname);
 276 #if OS2
 277         /*
 278          * Try $INIT/filename.
 279          */
 280         pathname = dirfile(lgetenv("INIT"), filename);
 281         if (pathname != NULL)
 282                 return (pathname);
 283 #endif
 284 #if MSDOS_COMPILER || OS2
 285         /*
 286          * Look for the file anywhere on search path.
 287          */
 288         pathname = (char *) calloc(_MAX_PATH, sizeof(char));
 289 #if MSDOS_COMPILER==DJGPPC
 290         {
 291                 char *res = searchpath(filename);
 292                 if (res == 0)
 293                         *pathname = '\0';
 294                 else
 295                         strcpy(pathname, res);
 296         }
 297 #else
 298         _searchenv(filename, "PATH", pathname);
 299 #endif
 300         if (*pathname != '\0')
 301                 return (pathname);
 302         free(pathname);
 303 #endif
 304         return (NULL);
 305 }
 306
 307 /*
 308  * Expand a string, substituting any "%" with the current filename,
 309  * and any "#" with the previous filename.
 310  * But a string of N "%"s is just replaced with N-1 "%"s.
 311  * Likewise for a string of N "#"s.
 312  * {{ This is a lot of work just to support % and #. }}
 313  */
 314         public char *
 315 fexpand(s)
 316         char *s;
 317 {
 318         register char *fr, *to;
 319         register int n;
 320         register char *e;
 321         IFILE ifile;
 322
 323 #define fchar_ifile(c) \
 324         ((c) == '%' ? curr_ifile : \
 325          (c) == '#' ? old_ifile : NULL_IFILE)
 326
 327         /*
 328          * Make one pass to see how big a buffer we
 329          * need to allocate for the expanded string.
 330          */
 331         n = 0;
 332         for (fr = s;  *fr != '\0';  fr++)
 333         {
 334                 switch (*fr)
 335                 {
 336                 case '%':
 337                 case '#':
 338                         if (fr > s && fr[-1] == *fr)
 339                         {
 340                                 /*
 341                                  * Second (or later) char in a string
 342                                  * of identical chars.  Treat as normal.
 343                                  */
 344                                 n++;
 345                         } else if (fr[1] != *fr)
 346                         {
 347                                 /*
 348                                  * Single char (not repeated).  Treat specially.
 349                                  */
 350                                 ifile = fchar_ifile(*fr);
 351                                 if (ifile == NULL_IFILE)
 352                                         n++;
 353                                 else
 354                                         n += strlen(get_filename(ifile));
 355                         }
 356                         /*
 357                          * Else it is the first char in a string of
 358                          * identical chars.  Just discard it.
 359                          */
 360                         break;
 361                 default:
 362                         n++;
 363                         break;
 364                 }
 365         }
 366
 367         e = (char *) ecalloc(n+1, sizeof(char));
 368
 369         /*
 370          * Now copy the string, expanding any "%" or "#".
 371          */
 372         to = e;
 373         for (fr = s;  *fr != '\0';  fr++)
 374         {
 375                 switch (*fr)
 376                 {
 377                 case '%':
 378                 case '#':
 379                         if (fr > s && fr[-1] == *fr)
 380                         {
 381                                 *to++ = *fr;
 382                         } else if (fr[1] != *fr)
 383                         {
 384                                 ifile = fchar_ifile(*fr);
 385                                 if (ifile == NULL_IFILE)
 386                                         *to++ = *fr;
 387                                 else
 388                                 {
 389                                         strcpy(to, get_filename(ifile));
 390                                         to += strlen(to);
 391                                 }
 392                         }
 393                         break;
 394                 default:
 395                         *to++ = *fr;
 396                         break;
 397                 }
 398         }
 399         *to = '\0';
 400         return (e);
 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 = 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 = 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         pend = &data[n];
 485         for (p = data;  p < pend;  )
 486         {
 487                 LWCHAR c = step_char(&p, +1, pend);
 488                 if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
 489                 {
 490                         do {
 491                                 c = step_char(&p, +1, pend);
 492                         } while (p < pend && is_ansi_middle(c));
 493                 } else if (binary_char(c))
 494                         bin_count++;
 495         }
 496         /*
 497          * Call it a binary file if there are more than 5 binary characters
 498          * in the first 256 bytes of the file.
 499          */
 500         return (bin_count > 5);
 501 }
 502
 503 /*
 504  * Try to determine the size of a file by seeking to the end.
 505  */
 506         static POSITION
 507 seek_filesize(f)
 508         int f;
 509 {
 510         off_t spos;
 511
 512         spos = lseek(f, (off_t)0, SEEK_END);
 513         if (spos == BAD_LSEEK)
 514                 return (NULL_POSITION);
 515         return ((POSITION) spos);
 516 }
 517
 518 /*
 519  * Read a string from a file.
 520  * Return a pointer to the string in memory.
 521  */
 522         static char *
 523 readfd(fd)
 524         FILE *fd;
 525 {
 526         int len;
 527         int ch;
 528         char *buf;
 529         char *p;
 530
 531         /*
 532          * Make a guess about how many chars in the string
 533          * and allocate a buffer to hold it.
 534          */
 535         len = 100;
 536         buf = (char *) ecalloc(len, sizeof(char));
 537         for (p = buf;  ;  p++)
 538         {
 539                 if ((ch = getc(fd)) == '\n' || ch == EOF)
 540                         break;
 541                 if (p - buf >= len-1)
 542                 {
 543                         /*
 544                          * The string is too big to fit in the buffer we have.
 545                          * Allocate a new buffer, twice as big.
 546                          */
 547                         len *= 2;
 548                         *p = '\0';
 549                         p = (char *) ecalloc(len, sizeof(char));
 550                         strcpy(p, buf);
 551                         free(buf);
 552                         buf = p;
 553                         p = buf + strlen(buf);
 554                 }
 555                 *p = ch;
 556         }
 557         *p = '\0';
 558         return (buf);
 559 }
 560
 561
 562
 563 #if HAVE_POPEN
 564
 565 FILE *popen();
 566
 567 /*
 568  * Execute a shell command.
 569  * Return a pointer to a pipe connected to the shell command's standard output.
 570  */
 571         static FILE *
 572 shellcmd(cmd)
 573         char *cmd;
 574 {
 575         FILE *fd;
 576
 577 #if HAVE_SHELL
 578         char *shell;
 579
 580         shell = lgetenv("SHELL");
 581         if (shell != NULL && *shell != '\0')
 582         {
 583                 char *scmd;
 584                 char *esccmd;
 585
 586                 /*
 587                  * Read the output of <$SHELL -c cmd>.
 588                  * Escape any metacharacters in the command.
 589                  */
 590                 esccmd = shell_quote(cmd);
 591                 if (esccmd == NULL)
 592                 {
 593                         fd = popen(cmd, "r");
 594                 } else
 595                 {
 596                         int len = strlen(shell) + strlen(esccmd) + 5;
 597                         scmd = (char *) ecalloc(len, sizeof(char));
 598                         SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
 599                         free(esccmd);
 600                         fd = popen(scmd, "r");
 601                         free(scmd);
 602                 }
 603         } else
 604 #endif
 605         {
 606                 fd = popen(cmd, "r");
 607         }
 608         /*
 609          * Redirection in `popen' might have messed with the
 610          * standard devices.  Restore binary input mode.
 611          */
 612         SET_BINARY(0);
 613         return (fd);
 614 }
 615
 616 #endif /* HAVE_POPEN */
 617
 618
 619 /*
 620  * Expand a filename, doing any system-specific metacharacter substitutions.
 621  */
 622         public char *
 623 lglob(filename)
 624         char *filename;
 625 {
 626         char *gfilename;
 627         char *ofilename;
 628
 629         ofilename = fexpand(filename);
 630         if (secure)
 631                 return (ofilename);
 632         filename = shell_unquote(ofilename);
 633
 634 #ifdef DECL_GLOB_LIST
 635 {
 636         /*
 637          * The globbing function returns a list of names.
 638          */
 639         int length;
 640         char *p;
 641         char *qfilename;
 642         DECL_GLOB_LIST(list)
 643
 644         GLOB_LIST(filename, list);
 645         if (GLOB_LIST_FAILED(list))
 646         {
 647                 free(filename);
 648                 return (ofilename);
 649         }
 650         length = 1; /* Room for trailing null byte */
 651         for (SCAN_GLOB_LIST(list, p))
 652         {
 653                 INIT_GLOB_LIST(list, p);
 654                 qfilename = shell_quote(p);
 655                 if (qfilename != NULL)
 656                 {
 657                         length += strlen(qfilename) + 1;
 658                         free(qfilename);
 659                 }
 660         }
 661         gfilename = (char *) ecalloc(length, sizeof(char));
 662         for (SCAN_GLOB_LIST(list, p))
 663         {
 664                 INIT_GLOB_LIST(list, p);
 665                 qfilename = shell_quote(p);
 666                 if (qfilename != NULL)
 667                 {
 668                         sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
 669                         free(qfilename);
 670                 }
 671         }
 672         /*
 673          * Overwrite the final trailing space with a null terminator.
 674          */
 675         *--p = '\0';
 676         GLOB_LIST_DONE(list);
 677 }
 678 #else
 679 #ifdef DECL_GLOB_NAME
 680 {
 681         /*
 682          * The globbing function returns a single name, and
 683          * is called multiple times to walk thru all names.
 684          */
 685         register char *p;
 686         register int len;
 687         register int n;
 688         char *pathname;
 689         char *qpathname;
 690         DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
 691
 692         GLOB_FIRST_NAME(filename, &fnd, handle);
 693         if (GLOB_FIRST_FAILED(handle))
 694         {
 695                 free(filename);
 696                 return (ofilename);
 697         }
 698
 699         _splitpath(filename, drive, dir, fname, ext);
 700         len = 100;
 701         gfilename = (char *) ecalloc(len, sizeof(char));
 702         p = gfilename;
 703         do {
 704                 n = strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1;
 705                 pathname = (char *) ecalloc(n, sizeof(char));
 706                 SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
 707                 qpathname = shell_quote(pathname);
 708                 free(pathname);
 709                 if (qpathname != NULL)
 710                 {
 711                         n = strlen(qpathname);
 712                         while (p - gfilename + n + 2 >= len)
 713                         {
 714                                 /*
 715                                  * No room in current buffer.
 716                                  * Allocate a bigger one.
 717                                  */
 718                                 len *= 2;
 719                                 *p = '\0';
 720                                 p = (char *) ecalloc(len, sizeof(char));
 721                                 strcpy(p, gfilename);
 722                                 free(gfilename);
 723                                 gfilename = p;
 724                                 p = gfilename + strlen(gfilename);
 725                         }
 726                         strcpy(p, qpathname);
 727                         free(qpathname);
 728                         p += n;
 729                         *p++ = ' ';
 730                 }
 731         } while (GLOB_NEXT_NAME(handle, &fnd) == 0);
 732
 733         /*
 734          * Overwrite the final trailing space with a null terminator.
 735          */
 736         *--p = '\0';
 737         GLOB_NAME_DONE(handle);
 738 }
 739 #else
 740 #if HAVE_POPEN
 741 {
 742         /*
 743          * We get the shell to glob the filename for us by passing
 744          * an "echo" command to the shell and reading its output.
 745          */
 746         FILE *fd;
 747         char *s;
 748         char *lessecho;
 749         char *cmd;
 750         char *esc;
 751         int len;
 752
 753         esc = get_meta_escape();
 754         if (strlen(esc) == 0)
 755                 esc = "-";
 756         esc = shell_quote(esc);
 757         if (esc == NULL)
 758         {
 759                 free(filename);
 760                 return (ofilename);
 761         }
 762         lessecho = lgetenv("LESSECHO");
 763         if (lessecho == NULL || *lessecho == '\0')
 764                 lessecho = "lessecho";
 765         /*
 766          * Invoke lessecho, and read its output (a globbed list of filenames).
 767          */
 768         len = strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24;
 769         cmd = (char *) ecalloc(len, sizeof(char));
 770         SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
 771         free(esc);
 772         for (s = metachars();  *s != '\0';  s++)
 773                 sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
 774         sprintf(cmd + strlen(cmd), "-- %s", ofilename);
 775         fd = shellcmd(cmd);
 776         free(cmd);
 777         if (fd == NULL)
 778         {
 779                 /*
 780                  * Cannot create the pipe.
 781                  * Just return the original (fexpanded) filename.
 782                  */
 783                 free(filename);
 784                 return (ofilename);
 785         }
 786         gfilename = readfd(fd);
 787         pclose(fd);
 788         if (*gfilename == '\0')
 789         {
 790                 free(gfilename);
 791                 free(filename);
 792                 return (ofilename);
 793         }
 794 }
 795 #else
 796         /*
 797          * No globbing functions at all.  Just use the fexpanded filename.
 798          */
 799         gfilename = save(filename);
 800 #endif
 801 #endif
 802 #endif
 803         free(filename);
 804         free(ofilename);
 805         return (gfilename);
 806 }
 807
 808 /*
 809  * See if we should open a "replacement file"
 810  * instead of the file we're about to open.
 811  */
 812         public char *
 813 open_altfile(filename, pf, pfd)
 814         char *filename;
 815         int *pf;
 816         void **pfd;
 817 {
 818 #if !HAVE_POPEN
 819         return (NULL);
 820 #else
 821         char *lessopen;
 822         char *cmd;
 823         int len;
 824         FILE *fd;
 825 #if HAVE_FILENO
 826         int returnfd = 0;
 827 #endif
 828
 829         if (!use_lessopen || secure)
 830                 return (NULL);
 831         ch_ungetchar(-1);
 832         if ((lessopen = lgetenv("LESSOPEN")) == NULL)
 833                 return (NULL);
 834         if (*lessopen == '|')
 835         {
 836                 /*
 837                  * If LESSOPEN starts with a |, it indicates
 838                  * a "pipe preprocessor".
 839                  */
 840 #if !HAVE_FILENO
 841                 error("LESSOPEN pipe is not supported", NULL_PARG);
 842                 return (NULL);
 843 #else
 844                 lessopen++;
 845                 returnfd = 1;
 846                 if (*lessopen == '-') {
 847                         /*
 848                          * Lessopen preprocessor will accept "-" as a filename.
 849                          */
 850                         lessopen++;
 851                 } else {
 852                         if (strcmp(filename, "-") == 0)
 853                                 return (NULL);
 854                 }
 855 #endif
 856         }
 857
 858         len = strlen(lessopen) + strlen(filename) + 2;
 859         cmd = (char *) ecalloc(len, sizeof(char));
 860         SNPRINTF1(cmd, len, lessopen, filename);
 861         fd = shellcmd(cmd);
 862         free(cmd);
 863         if (fd == NULL)
 864         {
 865                 /*
 866                  * Cannot create the pipe.
 867                  */
 868                 return (NULL);
 869         }
 870 #if HAVE_FILENO
 871         if (returnfd)
 872         {
 873                 int f;
 874                 char c;
 875
 876                 /*
 877                  * Read one char to see if the pipe will produce any data.
 878                  * If it does, push the char back on the pipe.
 879                  */
 880                 f = fileno(fd);
 881                 SET_BINARY(f);
 882                 if (read(f, &c, 1) != 1)
 883                 {
 884                         /*
 885                          * Pipe is empty.  This means there is no alt file.
 886                          */
 887                         pclose(fd);
 888                         return (NULL);
 889                 }
 890                 ch_ungetchar(c);
 891                 *pfd = (void *) fd;
 892                 *pf = f;
 893                 return (save("-"));
 894         }
 895 #endif
 896         cmd = readfd(fd);
 897         pclose(fd);
 898         if (*cmd == '\0')
 899                 /*
 900                  * Pipe is empty.  This means there is no alt file.
 901                  */
 902                 return (NULL);
 903         return (cmd);
 904 #endif /* HAVE_POPEN */
 905 }
 906
 907 /*
 908  * Close a replacement file.
 909  */
 910         public void
 911 close_altfile(altfilename, filename, pipefd)
 912         char *altfilename;
 913         char *filename;
 914         void *pipefd;
 915 {
 916 #if HAVE_POPEN
 917         char *lessclose;
 918         FILE *fd;
 919         char *cmd;
 920         int len;
 921
 922         if (secure)
 923                 return;
 924         if (pipefd != NULL)
 925         {
 926 #if OS2
 927                 /*
 928                  * The pclose function of OS/2 emx sometimes fails.
 929                  * Send SIGINT to the piped process before closing it.
 930                  */
 931                 kill(((FILE*)pipefd)->_pid, SIGINT);
 932 #endif
 933                 pclose((FILE*) pipefd);
 934         }
 935         if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
 936                 return;
 937         len = strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2;
 938         cmd = (char *) ecalloc(len, sizeof(char));
 939         SNPRINTF2(cmd, len, lessclose, filename, altfilename);
 940         fd = shellcmd(cmd);
 941         free(cmd);
 942         if (fd != NULL)
 943                 pclose(fd);
 944 #endif
 945 }
 946
 947 /*
 948  * Is the specified file a directory?
 949  */
 950         public int
 951 is_dir(filename)
 952         char *filename;
 953 {
 954         int isdir = 0;
 955
 956         filename = shell_unquote(filename);
 957 #if HAVE_STAT
 958 {
 959         int r;
 960         struct stat statbuf;
 961
 962         r = stat(filename, &statbuf);
 963         isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
 964 }
 965 #else
 966 #ifdef _OSK
 967 {
 968         register int f;
 969
 970         f = open(filename, S_IREAD | S_IFDIR);
 971         if (f >= 0)
 972                 close(f);
 973         isdir = (f >= 0);
 974 }
 975 #endif
 976 #endif
 977         free(filename);
 978         return (isdir);
 979 }
 980
 981 /*
 982  * Returns NULL if the file can be opened and
 983  * is an ordinary file, otherwise an error message
 984  * (if it cannot be opened or is a directory, etc.)
 985  */
 986         public char *
 987 bad_file(filename)
 988         char *filename;
 989 {
 990         register char *m = NULL;
 991
 992         filename = shell_unquote(filename);
 993         if (!force_open && is_dir(filename))
 994         {
 995                 static char is_a_dir[] = " is a directory";
 996
 997                 m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
 998                         sizeof(char));
 999                 strcpy(m, filename);
1000                 strcat(m, is_a_dir);
1001         } else
1002         {
1003 #if HAVE_STAT
1004                 int r;
1005                 struct stat statbuf;
1006
1007                 r = stat(filename, &statbuf);
1008                 if (r < 0)
1009                 {
1010                         m = errno_message(filename);
1011                 } else if (force_open)
1012                 {
1013                         m = NULL;
1014                 } else if (!S_ISREG(statbuf.st_mode))
1015                 {
1016                         static char not_reg[] = " is not a regular file (use -f to see it)";
1017                         m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1018                                 sizeof(char));
1019                         strcpy(m, filename);
1020                         strcat(m, not_reg);
1021                 }
1022 #endif
1023         }
1024         free(filename);
1025         return (m);
1026 }
1027
1028 /*
1029  * Return the size of a file, as cheaply as possible.
1030  * In Unix, we can stat the file.
1031  */
1032         public POSITION
1033 filesize(f)
1034         int f;
1035 {
1036 #if HAVE_STAT
1037         struct stat statbuf;
1038
1039         if (fstat(f, &statbuf) >= 0)
1040                 return ((POSITION) statbuf.st_size);
1041 #else
1042 #ifdef _OSK
1043         long size;
1044
1045         if ((size = (long) _gs_size(f)) >= 0)
1046                 return ((POSITION) size);
1047 #endif
1048 #endif
1049         return (seek_filesize(f));
1050 }
1051
1052 /*
1053  *
1054  */
1055         public char *
1056 shell_coption()
1057 {
1058         return ("-c");
1059 }