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 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 i;
 474         int n;
 475         int bin_count = 0;
 476         unsigned char data[256];
 477
 478         if (!seekable(f))
 479                 return (0);
 480         if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
 481                 return (0);
 482         n = read(f, data, sizeof(data));
 483         for (i = 0;  i < n;  i++)
 484         {
 485                 char c = data[i];
 486                 if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
 487                 {
 488                         while (++i < n && is_ansi_middle(data[i]))
 489                                 continue;
 490                 } else if (binary_char(c))
 491                         bin_count++;
 492         }
 493         /*
 494          * Call it a binary file if there are more than 5 binary characters
 495          * in the first 256 bytes of the file.
 496          */
 497         return (bin_count > 5);
 498 }
 499
 500 /*
 501  * Try to determine the size of a file by seeking to the end.
 502  */
 503         static POSITION
 504 seek_filesize(f)
 505         int f;
 506 {
 507         off_t spos;
 508
 509         spos = lseek(f, (off_t)0, SEEK_END);
 510         if (spos == BAD_LSEEK)
 511                 return (NULL_POSITION);
 512         return ((POSITION) spos);
 513 }
 514
 515 /*
 516  * Read a string from a file.
 517  * Return a pointer to the string in memory.
 518  */
 519         static char *
 520 readfd(fd)
 521         FILE *fd;
 522 {
 523         int len;
 524         int ch;
 525         char *buf;
 526         char *p;
 527
 528         /*
 529          * Make a guess about how many chars in the string
 530          * and allocate a buffer to hold it.
 531          */
 532         len = 100;
 533         buf = (char *) ecalloc(len, sizeof(char));
 534         for (p = buf;  ;  p++)
 535         {
 536                 if ((ch = getc(fd)) == '\n' || ch == EOF)
 537                         break;
 538                 if (p - buf >= len-1)
 539                 {
 540                         /*
 541                          * The string is too big to fit in the buffer we have.
 542                          * Allocate a new buffer, twice as big.
 543                          */
 544                         len *= 2;
 545                         *p = '\0';
 546                         p = (char *) ecalloc(len, sizeof(char));
 547                         strcpy(p, buf);
 548                         free(buf);
 549                         buf = p;
 550                         p = buf + strlen(buf);
 551                 }
 552                 *p = ch;
 553         }
 554         *p = '\0';
 555         return (buf);
 556 }
 557
 558
 559
 560 #if HAVE_POPEN
 561
 562 FILE *popen();
 563
 564 /*
 565  * Execute a shell command.
 566  * Return a pointer to a pipe connected to the shell command's standard output.
 567  */
 568         static FILE *
 569 shellcmd(cmd)
 570         char *cmd;
 571 {
 572         FILE *fd;
 573
 574 #if HAVE_SHELL
 575         char *shell;
 576
 577         shell = lgetenv("SHELL");
 578         if (shell != NULL && *shell != '\0')
 579         {
 580                 char *scmd;
 581                 char *esccmd;
 582
 583                 /*
 584                  * Read the output of <$SHELL -c cmd>.
 585                  * Escape any metacharacters in the command.
 586                  */
 587                 esccmd = shell_quote(cmd);
 588                 if (esccmd == NULL)
 589                 {
 590                         fd = popen(cmd, "r");
 591                 } else
 592                 {
 593                         int len = strlen(shell) + strlen(esccmd) + 5;
 594                         scmd = (char *) ecalloc(len, sizeof(char));
 595                         SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
 596                         free(esccmd);
 597                         fd = popen(scmd, "r");
 598                         free(scmd);
 599                 }
 600         } else
 601 #endif
 602         {
 603                 fd = popen(cmd, "r");
 604         }
 605         /*
 606          * Redirection in `popen' might have messed with the
 607          * standard devices.  Restore binary input mode.
 608          */
 609         SET_BINARY(0);
 610         return (fd);
 611 }
 612
 613 #endif /* HAVE_POPEN */
 614
 615
 616 /*
 617  * Expand a filename, doing any system-specific metacharacter substitutions.
 618  */
 619         public char *
 620 lglob(filename)
 621         char *filename;
 622 {
 623         char *gfilename;
 624         char *ofilename;
 625
 626         ofilename = fexpand(filename);
 627         if (secure)
 628                 return (ofilename);
 629         filename = shell_unquote(ofilename);
 630
 631 #ifdef DECL_GLOB_LIST
 632 {
 633         /*
 634          * The globbing function returns a list of names.
 635          */
 636         int length;
 637         char *p;
 638         char *qfilename;
 639         DECL_GLOB_LIST(list)
 640
 641         GLOB_LIST(filename, list);
 642         if (GLOB_LIST_FAILED(list))
 643         {
 644                 free(filename);
 645                 return (ofilename);
 646         }
 647         length = 1; /* Room for trailing null byte */
 648         for (SCAN_GLOB_LIST(list, p))
 649         {
 650                 INIT_GLOB_LIST(list, p);
 651                 qfilename = shell_quote(p);
 652                 if (qfilename != NULL)
 653                 {
 654                         length += strlen(qfilename) + 1;
 655                         free(qfilename);
 656                 }
 657         }
 658         gfilename = (char *) ecalloc(length, sizeof(char));
 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                         sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
 666                         free(qfilename);
 667                 }
 668         }
 669         /*
 670          * Overwrite the final trailing space with a null terminator.
 671          */
 672         *--p = '\0';
 673         GLOB_LIST_DONE(list);
 674 }
 675 #else
 676 #ifdef DECL_GLOB_NAME
 677 {
 678         /*
 679          * The globbing function returns a single name, and
 680          * is called multiple times to walk thru all names.
 681          */
 682         register char *p;
 683         register int len;
 684         register int n;
 685         char *pathname;
 686         char *qpathname;
 687         DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
 688
 689         GLOB_FIRST_NAME(filename, &fnd, handle);
 690         if (GLOB_FIRST_FAILED(handle))
 691         {
 692                 free(filename);
 693                 return (ofilename);
 694         }
 695
 696         _splitpath(filename, drive, dir, fname, ext);
 697         len = 100;
 698         gfilename = (char *) ecalloc(len, sizeof(char));
 699         p = gfilename;
 700         do {
 701                 n = strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1;
 702                 pathname = (char *) ecalloc(n, sizeof(char));
 703                 SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
 704                 qpathname = shell_quote(pathname);
 705                 free(pathname);
 706                 if (qpathname != NULL)
 707                 {
 708                         n = strlen(qpathname);
 709                         while (p - gfilename + n + 2 >= len)
 710                         {
 711                                 /*
 712                                  * No room in current buffer.
 713                                  * Allocate a bigger one.
 714                                  */
 715                                 len *= 2;
 716                                 *p = '\0';
 717                                 p = (char *) ecalloc(len, sizeof(char));
 718                                 strcpy(p, gfilename);
 719                                 free(gfilename);
 720                                 gfilename = p;
 721                                 p = gfilename + strlen(gfilename);
 722                         }
 723                         strcpy(p, qpathname);
 724                         free(qpathname);
 725                         p += n;
 726                         *p++ = ' ';
 727                 }
 728         } while (GLOB_NEXT_NAME(handle, &fnd) == 0);
 729
 730         /*
 731          * Overwrite the final trailing space with a null terminator.
 732          */
 733         *--p = '\0';
 734         GLOB_NAME_DONE(handle);
 735 }
 736 #else
 737 #if HAVE_POPEN
 738 {
 739         /*
 740          * We get the shell to glob the filename for us by passing
 741          * an "echo" command to the shell and reading its output.
 742          */
 743         FILE *fd;
 744         char *s;
 745         char *lessecho;
 746         char *cmd;
 747         char *esc;
 748         int len;
 749
 750         esc = get_meta_escape();
 751         if (strlen(esc) == 0)
 752                 esc = "-";
 753         esc = shell_quote(esc);
 754         if (esc == NULL)
 755         {
 756                 free(filename);
 757                 return (ofilename);
 758         }
 759         lessecho = lgetenv("LESSECHO");
 760         if (lessecho == NULL || *lessecho == '\0')
 761                 lessecho = "lessecho";
 762         /*
 763          * Invoke lessecho, and read its output (a globbed list of filenames).
 764          */
 765         len = strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24;
 766         cmd = (char *) ecalloc(len, sizeof(char));
 767         SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
 768         free(esc);
 769         for (s = metachars();  *s != '\0';  s++)
 770                 sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
 771         sprintf(cmd + strlen(cmd), "-- %s", ofilename);
 772         fd = shellcmd(cmd);
 773         free(cmd);
 774         if (fd == NULL)
 775         {
 776                 /*
 777                  * Cannot create the pipe.
 778                  * Just return the original (fexpanded) filename.
 779                  */
 780                 free(filename);
 781                 return (ofilename);
 782         }
 783         gfilename = readfd(fd);
 784         pclose(fd);
 785         if (*gfilename == '\0')
 786         {
 787                 free(gfilename);
 788                 free(filename);
 789                 return (ofilename);
 790         }
 791 }
 792 #else
 793         /*
 794          * No globbing functions at all.  Just use the fexpanded filename.
 795          */
 796         gfilename = save(filename);
 797 #endif
 798 #endif
 799 #endif
 800         free(filename);
 801         free(ofilename);
 802         return (gfilename);
 803 }
 804
 805 /*
 806  * See if we should open a "replacement file"
 807  * instead of the file we're about to open.
 808  */
 809         public char *
 810 open_altfile(filename, pf, pfd)
 811         char *filename;
 812         int *pf;
 813         void **pfd;
 814 {
 815 #if !HAVE_POPEN
 816         return (NULL);
 817 #else
 818         char *lessopen;
 819         char *cmd;
 820         int len;
 821         FILE *fd;
 822 #if HAVE_FILENO
 823         int returnfd = 0;
 824 #endif
 825
 826         if (!use_lessopen || secure)
 827                 return (NULL);
 828         ch_ungetchar(-1);
 829         if ((lessopen = lgetenv("LESSOPEN")) == NULL)
 830                 return (NULL);
 831         if (strcmp(filename, "-") == 0)
 832                 return (NULL);
 833         if (*lessopen == '|')
 834         {
 835                 /*
 836                  * If LESSOPEN starts with a |, it indicates
 837                  * a "pipe preprocessor".
 838                  */
 839 #if HAVE_FILENO
 840                 lessopen++;
 841                 returnfd = 1;
 842 #else
 843                 error("LESSOPEN pipe is not supported", NULL_PARG);
 844                 return (NULL);
 845 #endif
 846         }
 847
 848         len = strlen(lessopen) + strlen(filename) + 2;
 849         cmd = (char *) ecalloc(len, sizeof(char));
 850         SNPRINTF1(cmd, len, lessopen, filename);
 851         fd = shellcmd(cmd);
 852         free(cmd);
 853         if (fd == NULL)
 854         {
 855                 /*
 856                  * Cannot create the pipe.
 857                  */
 858                 return (NULL);
 859         }
 860 #if HAVE_FILENO
 861         if (returnfd)
 862         {
 863                 int f;
 864                 char c;
 865
 866                 /*
 867                  * Read one char to see if the pipe will produce any data.
 868                  * If it does, push the char back on the pipe.
 869                  */
 870                 f = fileno(fd);
 871                 SET_BINARY(f);
 872                 if (read(f, &c, 1) != 1)
 873                 {
 874                         /*
 875                          * Pipe is empty.  This means there is no alt file.
 876                          */
 877                         pclose(fd);
 878                         return (NULL);
 879                 }
 880                 ch_ungetchar(c);
 881                 *pfd = (void *) fd;
 882                 *pf = f;
 883                 return (save("-"));
 884         }
 885 #endif
 886         cmd = readfd(fd);
 887         pclose(fd);
 888         if (*cmd == '\0')
 889                 /*
 890                  * Pipe is empty.  This means there is no alt file.
 891                  */
 892                 return (NULL);
 893         return (cmd);
 894 #endif /* HAVE_POPEN */
 895 }
 896
 897 /*
 898  * Close a replacement file.
 899  */
 900         public void
 901 close_altfile(altfilename, filename, pipefd)
 902         char *altfilename;
 903         char *filename;
 904         void *pipefd;
 905 {
 906 #if HAVE_POPEN
 907         char *lessclose;
 908         FILE *fd;
 909         char *cmd;
 910         int len;
 911
 912         if (secure)
 913                 return;
 914         if (pipefd != NULL)
 915         {
 916 #if OS2
 917                 /*
 918                  * The pclose function of OS/2 emx sometimes fails.
 919                  * Send SIGINT to the piped process before closing it.
 920                  */
 921                 kill(((FILE*)pipefd)->_pid, SIGINT);
 922 #endif
 923                 pclose((FILE*) pipefd);
 924         }
 925         if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
 926                 return;
 927         len = strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2;
 928         cmd = (char *) ecalloc(len, sizeof(char));
 929         SNPRINTF2(cmd, len, lessclose, filename, altfilename);
 930         fd = shellcmd(cmd);
 931         free(cmd);
 932         if (fd != NULL)
 933                 pclose(fd);
 934 #endif
 935 }
 936
 937 /*
 938  * Is the specified file a directory?
 939  */
 940         public int
 941 is_dir(filename)
 942         char *filename;
 943 {
 944         int isdir = 0;
 945
 946         filename = shell_unquote(filename);
 947 #if HAVE_STAT
 948 {
 949         int r;
 950         struct stat statbuf;
 951
 952         r = stat(filename, &statbuf);
 953         isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
 954 }
 955 #else
 956 #ifdef _OSK
 957 {
 958         register int f;
 959
 960         f = open(filename, S_IREAD | S_IFDIR);
 961         if (f >= 0)
 962                 close(f);
 963         isdir = (f >= 0);
 964 }
 965 #endif
 966 #endif
 967         free(filename);
 968         return (isdir);
 969 }
 970
 971 /*
 972  * Returns NULL if the file can be opened and
 973  * is an ordinary file, otherwise an error message
 974  * (if it cannot be opened or is a directory, etc.)
 975  */
 976         public char *
 977 bad_file(filename)
 978         char *filename;
 979 {
 980         register char *m = NULL;
 981
 982         filename = shell_unquote(filename);
 983         if (!force_open && is_dir(filename))
 984         {
 985                 static char is_a_dir[] = " is a directory";
 986
 987                 m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
 988                         sizeof(char));
 989                 strcpy(m, filename);
 990                 strcat(m, is_a_dir);
 991         } else
 992         {
 993 #if HAVE_STAT
 994                 int r;
 995                 struct stat statbuf;
 996
 997                 r = stat(filename, &statbuf);
 998                 if (r < 0)
 999                 {
1000                         m = errno_message(filename);
1001                 } else if (force_open)
1002                 {
1003                         m = NULL;
1004                 } else if (!S_ISREG(statbuf.st_mode))
1005                 {
1006                         static char not_reg[] = " is not a regular file (use -f to see it)";
1007                         m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1008                                 sizeof(char));
1009                         strcpy(m, filename);
1010                         strcat(m, not_reg);
1011                 }
1012 #endif
1013         }
1014         free(filename);
1015         return (m);
1016 }
1017
1018 /*
1019  * Return the size of a file, as cheaply as possible.
1020  * In Unix, we can stat the file.
1021  */
1022         public POSITION
1023 filesize(f)
1024         int f;
1025 {
1026 #if HAVE_STAT
1027         struct stat statbuf;
1028
1029         if (fstat(f, &statbuf) >= 0)
1030                 return ((POSITION) statbuf.st_size);
1031 #else
1032 #ifdef _OSK
1033         long size;
1034
1035         if ((size = (long) _gs_size(f)) >= 0)
1036                 return ((POSITION) size);
1037 #endif
1038 #endif
1039         return (seek_filesize(f));
1040 }
1041
1042 /*
1043  *
1044  */
1045         public char *
1046 shell_coption()
1047 {
1048         return ("-c");
1049 }