contrib/less-4/filename.c

   1 /*
   2  * Copyright (C) 1984-2007  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 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 = 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 = 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 = 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= 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 += 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 #if TAB_COMPLETE_FILENAME
 403
 404 /*
 405  * Return a blank-separated list of filenames which "complete"
 406  * the given string.
 407  */
 408         public char *
 409 fcomplete(s)
 410         char *s;
 411 {
 412         char *fpat;
 413         char *qs;
 414
 415         if (secure)
 416                 return (NULL);
 417         /*
 418          * Complete the filename "s" by globbing "s*".
 419          */
 420 #if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
 421         /*
 422          * But in DOS, we have to glob "s*.*".
 423          * But if the final component of the filename already has
 424          * a dot in it, just do "s*".
 425          * (Thus, "FILE" is globbed as "FILE*.*",
 426          *  but "FILE.A" is globbed as "FILE.A*").
 427          */
 428         {
 429                 char *slash;
 430                 int len;
 431                 for (slash = s+strlen(s)-1;  slash > s;  slash--)
 432                         if (*slash == *PATHNAME_SEP || *slash == '/')
 433                                 break;
 434                 len = strlen(s) + 4;
 435                 fpat = (char *) ecalloc(len, sizeof(char));
 436                 if (strchr(slash, '.') == NULL)
 437                         SNPRINTF1(fpat, len, "%s*.*", s);
 438                 else
 439                         SNPRINTF1(fpat, len, "%s*", s);
 440         }
 441 #else
 442         {
 443         int len = strlen(s) + 2;
 444         fpat = (char *) ecalloc(len, sizeof(char));
 445         SNPRINTF1(fpat, len, "%s*", s);
 446         }
 447 #endif
 448         qs = lglob(fpat);
 449         s = shell_unquote(qs);
 450         if (strcmp(s,fpat) == 0)
 451         {
 452                 /*
 453                  * The filename didn't expand.
 454                  */
 455                 free(qs);
 456                 qs = NULL;
 457         }
 458         free(s);
 459         free(fpat);
 460         return (qs);
 461 }
 462 #endif
 463
 464 /*
 465  * Try to determine if a file is "binary".
 466  * This is just a guess, and we need not try too hard to make it accurate.
 467  */
 468         public int
 469 bin_file(f)
 470         int f;
 471 {
 472         int i;
 473         int n;
 474         int bin_count = 0;
 475         unsigned char data[256];
 476
 477         if (!seekable(f))
 478                 return (0);
 479         if (lseek(f, (off_t)0, 0) == BAD_LSEEK)
 480                 return (0);
 481         n = read(f, data, sizeof(data));
 482         for (i = 0;  i < n;  i++)
 483         {
 484                 char c = data[i];
 485                 if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
 486                 {
 487                         while (++i < n && is_ansi_middle(data[i]))
 488                                 continue;
 489                 } else if (binary_char(c))
 490                         bin_count++;
 491         }
 492         /*
 493          * Call it a binary file if there are more than 5 binary characters
 494          * in the first 256 bytes of the file.
 495          */
 496         return (bin_count > 5);
 497 }
 498
 499 /*
 500  * Try to determine the size of a file by seeking to the end.
 501  */
 502         static POSITION
 503 seek_filesize(f)
 504         int f;
 505 {
 506         off_t spos;
 507
 508         spos = lseek(f, (off_t)0, 2);
 509         if (spos == BAD_LSEEK)
 510                 return (NULL_POSITION);
 511         return ((POSITION) spos);
 512 }
 513
 514 /*
 515  * Read a string from a file.
 516  * Return a pointer to the string in memory.
 517  */
 518         static char *
 519 readfd(fd)
 520         FILE *fd;
 521 {
 522         int len;
 523         int ch;
 524         char *buf;
 525         char *p;
 526
 527         /*
 528          * Make a guess about how many chars in the string
 529          * and allocate a buffer to hold it.
 530          */
 531         len = 100;
 532         buf = (char *) ecalloc(len, sizeof(char));
 533         for (p = buf;  ;  p++)
 534         {
 535                 if ((ch = getc(fd)) == '\n' || ch == EOF)
 536                         break;
 537                 if (p - buf >= len-1)
 538                 {
 539                         /*
 540                          * The string is too big to fit in the buffer we have.
 541                          * Allocate a new buffer, twice as big.
 542                          */
 543                         len *= 2;
 544                         *p = '\0';
 545                         p = (char *) ecalloc(len, sizeof(char));
 546                         strcpy(p, buf);
 547                         free(buf);
 548                         buf = p;
 549                         p = buf + strlen(buf);
 550                 }
 551                 *p = ch;
 552         }
 553         *p = '\0';
 554         return (buf);
 555 }
 556
 557
 558
 559 #if HAVE_POPEN
 560
 561 FILE *popen();
 562
 563 /*
 564  * Execute a shell command.
 565  * Return a pointer to a pipe connected to the shell command's standard output.
 566  */
 567         static FILE *
 568 shellcmd(cmd)
 569         char *cmd;
 570 {
 571         FILE *fd;
 572
 573 #if HAVE_SHELL
 574         char *shell;
 575
 576         shell = lgetenv("SHELL");
 577         if (shell != NULL && *shell != '\0')
 578         {
 579                 char *scmd;
 580                 char *esccmd;
 581
 582                 /*
 583                  * Read the output of <$SHELL -c cmd>.
 584                  * Escape any metacharacters in the command.
 585                  */
 586                 esccmd = shell_quote(cmd);
 587                 if (esccmd == NULL)
 588                 {
 589                         fd = popen(cmd, "r");
 590                 } else
 591                 {
 592                         int len = strlen(shell) + strlen(esccmd) + 5;
 593                         scmd = (char *) ecalloc(len, sizeof(char));
 594                         SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
 595                         free(esccmd);
 596                         fd = popen(scmd, "r");
 597                         free(scmd);
 598                 }
 599         } else
 600 #endif
 601         {
 602                 fd = popen(cmd, "r");
 603         }
 604         /*
 605          * Redirection in `popen' might have messed with the
 606          * standard devices.  Restore binary input mode.
 607          */
 608         SET_BINARY(0);
 609         return (fd);
 610 }
 611
 612 #endif /* HAVE_POPEN */
 613
 614
 615 /*
 616  * Expand a filename, doing any system-specific metacharacter substitutions.
 617  */
 618         public char *
 619 lglob(filename)
 620         char *filename;
 621 {
 622         char *gfilename;
 623         char *ofilename;
 624
 625         ofilename = fexpand(filename);
 626         if (secure)
 627                 return (ofilename);
 628         filename = shell_unquote(ofilename);
 629
 630 #ifdef DECL_GLOB_LIST
 631 {
 632         /*
 633          * The globbing function returns a list of names.
 634          */
 635         int length;
 636         char *p;
 637         char *qfilename;
 638         DECL_GLOB_LIST(list)
 639
 640         GLOB_LIST(filename, list);
 641         if (GLOB_LIST_FAILED(list))
 642         {
 643                 free(filename);
 644                 return (ofilename);
 645         }
 646         length = 1; /* Room for trailing null byte */
 647         for (SCAN_GLOB_LIST(list, p))
 648         {
 649                 INIT_GLOB_LIST(list, p);
 650                 qfilename = shell_quote(p);
 651                 if (qfilename != NULL)
 652                 {
 653                         length += strlen(qfilename) + 1;
 654                         free(qfilename);
 655                 }
 656         }
 657         gfilename = (char *) ecalloc(length, sizeof(char));
 658         for (SCAN_GLOB_LIST(list, p))
 659         {
 660                 INIT_GLOB_LIST(list, p);
 661                 qfilename = shell_quote(p);
 662                 if (qfilename != NULL)
 663                 {
 664                         sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
 665                         free(qfilename);
 666                 }
 667         }
 668         /*
 669          * Overwrite the final trailing space with a null terminator.
 670          */
 671         *--p = '\0';
 672         GLOB_LIST_DONE(list);
 673 }
 674 #else
 675 #ifdef DECL_GLOB_NAME
 676 {
 677         /*
 678          * The globbing function returns a single name, and
 679          * is called multiple times to walk thru all names.
 680          */
 681         register char *p;
 682         register int len;
 683         register int n;
 684         char *pathname;
 685         char *qpathname;
 686         DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
 687
 688         GLOB_FIRST_NAME(filename, &fnd, handle);
 689         if (GLOB_FIRST_FAILED(handle))
 690         {
 691                 free(filename);
 692                 return (ofilename);
 693         }
 694
 695         _splitpath(filename, drive, dir, fname, ext);
 696         len = 100;
 697         gfilename = (char *) ecalloc(len, sizeof(char));
 698         p = gfilename;
 699         do {
 700                 n = strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1;
 701                 pathname = (char *) ecalloc(n, sizeof(char));
 702                 SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
 703                 qpathname = shell_quote(pathname);
 704                 free(pathname);
 705                 if (qpathname != NULL)
 706                 {
 707                         n = strlen(qpathname);
 708                         while (p - gfilename + n + 2 >= len)
 709                         {
 710                                 /*
 711                                  * No room in current buffer.
 712                                  * Allocate a bigger one.
 713                                  */
 714                                 len *= 2;
 715                                 *p = '\0';
 716                                 p = (char *) ecalloc(len, sizeof(char));
 717                                 strcpy(p, gfilename);
 718                                 free(gfilename);
 719                                 gfilename = p;
 720                                 p = gfilename + strlen(gfilename);
 721                         }
 722                         strcpy(p, qpathname);
 723                         free(qpathname);
 724                         p += n;
 725                         *p++ = ' ';
 726                 }
 727         } while (GLOB_NEXT_NAME(handle, &fnd) == 0);
 728
 729         /*
 730          * Overwrite the final trailing space with a null terminator.
 731          */
 732         *--p = '\0';
 733         GLOB_NAME_DONE(handle);
 734 }
 735 #else
 736 #if HAVE_POPEN
 737 {
 738         /*
 739          * We get the shell to glob the filename for us by passing
 740          * an "echo" command to the shell and reading its output.
 741          */
 742         FILE *fd;
 743         char *s;
 744         char *lessecho;
 745         char *cmd;
 746         char *esc;
 747         int len;
 748
 749         esc = get_meta_escape();
 750         if (strlen(esc) == 0)
 751                 esc = "-";
 752         esc = shell_quote(esc);
 753         if (esc == NULL)
 754         {
 755                 free(filename);
 756                 return (ofilename);
 757         }
 758         lessecho = lgetenv("LESSECHO");
 759         if (lessecho == NULL || *lessecho == '\0')
 760                 lessecho = "lessecho";
 761         /*
 762          * Invoke lessecho, and read its output (a globbed list of filenames).
 763          */
 764         len = strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24;
 765         cmd = (char *) ecalloc(len, sizeof(char));
 766         SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
 767         free(esc);
 768         for (s = metachars();  *s != '\0';  s++)
 769                 sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
 770         sprintf(cmd + strlen(cmd), "-- %s", ofilename);
 771         fd = shellcmd(cmd);
 772         free(cmd);
 773         if (fd == NULL)
 774         {
 775                 /*
 776                  * Cannot create the pipe.
 777                  * Just return the original (fexpanded) filename.
 778                  */
 779                 free(filename);
 780                 return (ofilename);
 781         }
 782         gfilename = readfd(fd);
 783         pclose(fd);
 784         if (*gfilename == '\0')
 785         {
 786                 free(gfilename);
 787                 free(filename);
 788                 return (ofilename);
 789         }
 790 }
 791 #else
 792         /*
 793          * No globbing functions at all.  Just use the fexpanded filename.
 794          */
 795         gfilename = save(filename);
 796 #endif
 797 #endif
 798 #endif
 799         free(filename);
 800         free(ofilename);
 801         return (gfilename);
 802 }
 803
 804 /*
 805  * See if we should open a "replacement file"
 806  * instead of the file we're about to open.
 807  */
 808         public char *
 809 open_altfile(filename, pf, pfd)
 810         char *filename;
 811         int *pf;
 812         void **pfd;
 813 {
 814 #if !HAVE_POPEN
 815         return (NULL);
 816 #else
 817         char *lessopen;
 818         char *cmd;
 819         int len;
 820         FILE *fd;
 821 #if HAVE_FILENO
 822         int returnfd = 0;
 823 #endif
 824
 825         if (!use_lessopen || secure)
 826                 return (NULL);
 827         ch_ungetchar(-1);
 828         if ((lessopen = lgetenv("LESSOPEN")) == NULL)
 829                 return (NULL);
 830         if (strcmp(filename, "-") == 0)
 831                 return (NULL);
 832         if (*lessopen == '|')
 833         {
 834                 /*
 835                  * If LESSOPEN starts with a |, it indicates
 836                  * a "pipe preprocessor".
 837                  */
 838 #if HAVE_FILENO
 839                 lessopen++;
 840                 returnfd = 1;
 841 #else
 842                 error("LESSOPEN pipe is not supported", NULL_PARG);
 843                 return (NULL);
 844 #endif
 845         }
 846
 847         len = strlen(lessopen) + strlen(filename) + 2;
 848         cmd = (char *) ecalloc(len, sizeof(char));
 849         SNPRINTF1(cmd, len, lessopen, filename);
 850         fd = shellcmd(cmd);
 851         free(cmd);
 852         if (fd == NULL)
 853         {
 854                 /*
 855                  * Cannot create the pipe.
 856                  */
 857                 return (NULL);
 858         }
 859 #if HAVE_FILENO
 860         if (returnfd)
 861         {
 862                 int f;
 863                 char c;
 864
 865                 /*
 866                  * Read one char to see if the pipe will produce any data.
 867                  * If it does, push the char back on the pipe.
 868                  */
 869                 f = fileno(fd);
 870                 SET_BINARY(f);
 871                 if (read(f, &c, 1) != 1)
 872                 {
 873                         /*
 874                          * Pipe is empty.  This means there is no alt file.
 875                          */
 876                         pclose(fd);
 877                         return (NULL);
 878                 }
 879                 ch_ungetchar(c);
 880                 *pfd = (void *) fd;
 881                 *pf = f;
 882                 return (save("-"));
 883         }
 884 #endif
 885         cmd = readfd(fd);
 886         pclose(fd);
 887         if (*cmd == '\0')
 888                 /*
 889                  * Pipe is empty.  This means there is no alt file.
 890                  */
 891                 return (NULL);
 892         return (cmd);
 893 #endif /* HAVE_POPEN */
 894 }
 895
 896 /*
 897  * Close a replacement file.
 898  */
 899         public void
 900 close_altfile(altfilename, filename, pipefd)
 901         char *altfilename;
 902         char *filename;
 903         void *pipefd;
 904 {
 905 #if HAVE_POPEN
 906         char *lessclose;
 907         FILE *fd;
 908         char *cmd;
 909         int len;
 910
 911         if (secure)
 912                 return;
 913         if (pipefd != NULL)
 914         {
 915 #if OS2
 916                 /*
 917                  * The pclose function of OS/2 emx sometimes fails.
 918                  * Send SIGINT to the piped process before closing it.
 919                  */
 920                 kill(((FILE*)pipefd)->_pid, SIGINT);
 921 #endif
 922                 pclose((FILE*) pipefd);
 923         }
 924         if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
 925                 return;
 926         len = strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2;
 927         cmd = (char *) ecalloc(len, sizeof(char));
 928         SNPRINTF2(cmd, len, lessclose, filename, altfilename);
 929         fd = shellcmd(cmd);
 930         free(cmd);
 931         if (fd != NULL)
 932                 pclose(fd);
 933 #endif
 934 }
 935
 936 /*
 937  * Is the specified file a directory?
 938  */
 939         public int
 940 is_dir(filename)
 941         char *filename;
 942 {
 943         int isdir = 0;
 944
 945         filename = shell_unquote(filename);
 946 #if HAVE_STAT
 947 {
 948         int r;
 949         struct stat statbuf;
 950
 951         r = stat(filename, &statbuf);
 952         isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
 953 }
 954 #else
 955 #ifdef _OSK
 956 {
 957         register int f;
 958
 959         f = open(filename, S_IREAD | S_IFDIR);
 960         if (f >= 0)
 961                 close(f);
 962         isdir = (f >= 0);
 963 }
 964 #endif
 965 #endif
 966         free(filename);
 967         return (isdir);
 968 }
 969
 970 /*
 971  * Returns NULL if the file can be opened and
 972  * is an ordinary file, otherwise an error message
 973  * (if it cannot be opened or is a directory, etc.)
 974  */
 975         public char *
 976 bad_file(filename)
 977         char *filename;
 978 {
 979         register char *m = NULL;
 980
 981         filename = shell_unquote(filename);
 982         if (!force_open && is_dir(filename))
 983         {
 984                 static char is_a_dir[] = " is a directory";
 985
 986                 m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
 987                         sizeof(char));
 988                 strcpy(m, filename);
 989                 strcat(m, is_a_dir);
 990         } else
 991         {
 992 #if HAVE_STAT
 993                 int r;
 994                 struct stat statbuf;
 995
 996                 r = stat(filename, &statbuf);
 997                 if (r < 0)
 998                 {
 999                         m = errno_message(filename);
1000                 } else if (force_open)
1001                 {
1002                         m = NULL;
1003                 } else if (!S_ISREG(statbuf.st_mode))
1004                 {
1005                         static char not_reg[] = " is not a regular file (use -f to see it)";
1006                         m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1007                                 sizeof(char));
1008                         strcpy(m, filename);
1009                         strcat(m, not_reg);
1010                 }
1011 #endif
1012         }
1013         free(filename);
1014         return (m);
1015 }
1016
1017 /*
1018  * Return the size of a file, as cheaply as possible.
1019  * In Unix, we can stat the file.
1020  */
1021         public POSITION
1022 filesize(f)
1023         int f;
1024 {
1025 #if HAVE_STAT
1026         struct stat statbuf;
1027
1028         if (fstat(f, &statbuf) >= 0)
1029                 return ((POSITION) statbuf.st_size);
1030 #else
1031 #ifdef _OSK
1032         long size;
1033
1034         if ((size = (long) _gs_size(f)) >= 0)
1035                 return ((POSITION) size);
1036 #endif
1037 #endif
1038         return (seek_filesize(f));
1039 }
1040
1041 /*
1042  *
1043  */
1044         public char *
1045 shell_coption()
1046 {
1047         return ("-c");
1048 }