contrib/less/filename.c

   1 /*
   2  * Copyright (C) 1984-2012  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information, see the README file.
   8  */
   9
  10
  11 /*
  12  * Routines to mess around with filenames (and files).
  13  * Much of this is very OS dependent.
  14  */
  15
  16 #include "less.h"
  17 #include "lglob.h"
  18 #if MSDOS_COMPILER
  19 #include <dos.h>
  20 #if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER)
  21 #include <dir.h>
  22 #endif
  23 #if MSDOS_COMPILER==DJGPPC
  24 #include <glob.h>
  25 #include <dir.h>
  26 #define _MAX_PATH       PATH_MAX
  27 #endif
  28 #endif
  29 #ifdef _OSK
  30 #include <rbf.h>
  31 #ifndef _OSK_MWC32
  32 #include <modes.h>
  33 #endif
  34 #endif
  35 #if OS2
  36 #include <signal.h>
  37 #endif
  38
  39 #if HAVE_STAT
  40 #include <sys/stat.h>
  41 #ifndef S_ISDIR
  42 #define S_ISDIR(m)      (((m) & S_IFMT) == S_IFDIR)
  43 #endif
  44 #ifndef S_ISREG
  45 #define S_ISREG(m)      (((m) & S_IFMT) == S_IFREG)
  46 #endif
  47 #endif
  48
  49
  50 extern int force_open;
  51 extern int secure;
  52 extern int use_lessopen;
  53 extern int ctldisp;
  54 extern int utf_mode;
  55 extern IFILE curr_ifile;
  56 extern IFILE old_ifile;
  57 #if SPACES_IN_FILENAMES
  58 extern char openquote;
  59 extern char closequote;
  60 #endif
  61
  62 /*
  63  * Remove quotes around a filename.
  64  */
  65         public char *
  66 shell_unquote(str)
  67         char *str;
  68 {
  69         char *name;
  70         char *p;
  71
  72         name = p = (char *) ecalloc(strlen(str)+1, sizeof(char));
  73         if (*str == openquote)
  74         {
  75                 str++;
  76                 while (*str != '\0')
  77                 {
  78                         if (*str == closequote)
  79                         {
  80                                 if (str[1] != closequote)
  81                                         break;
  82                                 str++;
  83                         }
  84                         *p++ = *str++;
  85                 }
  86         } else
  87         {
  88                 char *esc = get_meta_escape();
  89                 int esclen = 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
 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  * Return number of %s escapes in a string.
 810  * Return a large number if there are any other % escapes besides %s.
 811  */
 812         static int
 813 num_pct_s(lessopen)
 814         char *lessopen;
 815 {
 816         int num;
 817
 818         for (num = 0;; num++)
 819         {
 820                 lessopen = strchr(lessopen, '%');
 821                 if (lessopen == NULL)
 822                         break;
 823                 if (*++lessopen != 's')
 824                         return (999);
 825         }
 826         return (num);
 827 }
 828
 829 /*
 830  * See if we should open a "replacement file"
 831  * instead of the file we're about to open.
 832  */
 833         public char *
 834 open_altfile(filename, pf, pfd)
 835         char *filename;
 836         int *pf;
 837         void **pfd;
 838 {
 839 #if !HAVE_POPEN
 840         return (NULL);
 841 #else
 842         char *lessopen;
 843         char *cmd;
 844         int len;
 845         FILE *fd;
 846 #if HAVE_FILENO
 847         int returnfd = 0;
 848 #endif
 849
 850         if (!use_lessopen || secure)
 851                 return (NULL);
 852         ch_ungetchar(-1);
 853         if ((lessopen = lgetenv("LESSOPEN")) == NULL)
 854                 return (NULL);
 855         while (*lessopen == '|')
 856         {
 857                 /*
 858                  * If LESSOPEN starts with a |, it indicates
 859                  * a "pipe preprocessor".
 860                  */
 861 #if !HAVE_FILENO
 862                 error("LESSOPEN pipe is not supported", NULL_PARG);
 863                 return (NULL);
 864 #else
 865                 lessopen++;
 866                 returnfd++;
 867 #endif
 868         }
 869         if (*lessopen == '-') {
 870                 /*
 871                  * Lessopen preprocessor will accept "-" as a filename.
 872                  */
 873                 lessopen++;
 874         } else {
 875                 if (strcmp(filename, "-") == 0)
 876                         return (NULL);
 877         }
 878         if (num_pct_s(lessopen) > 1)
 879         {
 880                 error("Invalid LESSOPEN variable", NULL_PARG);
 881                 return (NULL);
 882         }
 883
 884         len = strlen(lessopen) + strlen(filename) + 2;
 885         cmd = (char *) ecalloc(len, sizeof(char));
 886         SNPRINTF1(cmd, len, lessopen, filename);
 887         fd = shellcmd(cmd);
 888         free(cmd);
 889         if (fd == NULL)
 890         {
 891                 /*
 892                  * Cannot create the pipe.
 893                  */
 894                 return (NULL);
 895         }
 896 #if HAVE_FILENO
 897         if (returnfd)
 898         {
 899                 int f;
 900                 char c;
 901
 902                 /*
 903                  * Read one char to see if the pipe will produce any data.
 904                  * If it does, push the char back on the pipe.
 905                  */
 906                 f = fileno(fd);
 907                 SET_BINARY(f);
 908                 if (read(f, &c, 1) != 1)
 909                 {
 910                         /*
 911                          * Pipe is empty.
 912                          * If more than 1 pipe char was specified,
 913                          * the exit status tells whether the file itself
 914                          * is empty, or if there is no alt file.
 915                          * If only one pipe char, just assume no alt file.
 916                          */
 917                         int status = pclose(fd);
 918                         if (returnfd > 1 && status == 0) {
 919                                 *pfd = NULL;
 920                                 *pf = -1;
 921                                 return (save(FAKE_EMPTYFILE));
 922                         }
 923                         return (NULL);
 924                 }
 925                 ch_ungetchar(c);
 926                 *pfd = (void *) fd;
 927                 *pf = f;
 928                 return (save("-"));
 929         }
 930 #endif
 931         cmd = readfd(fd);
 932         pclose(fd);
 933         if (*cmd == '\0')
 934                 /*
 935                  * Pipe is empty.  This means there is no alt file.
 936                  */
 937                 return (NULL);
 938         return (cmd);
 939 #endif /* HAVE_POPEN */
 940 }
 941
 942 /*
 943  * Close a replacement file.
 944  */
 945         public void
 946 close_altfile(altfilename, filename, pipefd)
 947         char *altfilename;
 948         char *filename;
 949         void *pipefd;
 950 {
 951 #if HAVE_POPEN
 952         char *lessclose;
 953         FILE *fd;
 954         char *cmd;
 955         int len;
 956
 957         if (secure)
 958                 return;
 959         if (pipefd != NULL)
 960         {
 961 #if OS2
 962                 /*
 963                  * The pclose function of OS/2 emx sometimes fails.
 964                  * Send SIGINT to the piped process before closing it.
 965                  */
 966                 kill(((FILE*)pipefd)->_pid, SIGINT);
 967 #endif
 968                 pclose((FILE*) pipefd);
 969         }
 970         if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
 971                 return;
 972         if (num_pct_s(lessclose) > 2)
 973         {
 974                 error("Invalid LESSCLOSE variable");
 975                 return;
 976         }
 977         len = strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2;
 978         cmd = (char *) ecalloc(len, sizeof(char));
 979         SNPRINTF2(cmd, len, lessclose, filename, altfilename);
 980         fd = shellcmd(cmd);
 981         free(cmd);
 982         if (fd != NULL)
 983                 pclose(fd);
 984 #endif
 985 }
 986
 987 /*
 988  * Is the specified file a directory?
 989  */
 990         public int
 991 is_dir(filename)
 992         char *filename;
 993 {
 994         int isdir = 0;
 995
 996         filename = shell_unquote(filename);
 997 #if HAVE_STAT
 998 {
 999         int r;
1000         struct stat statbuf;
1001
1002         r = stat(filename, &statbuf);
1003         isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
1004 }
1005 #else
1006 #ifdef _OSK
1007 {
1008         register int f;
1009
1010         f = open(filename, S_IREAD | S_IFDIR);
1011         if (f >= 0)
1012                 close(f);
1013         isdir = (f >= 0);
1014 }
1015 #endif
1016 #endif
1017         free(filename);
1018         return (isdir);
1019 }
1020
1021 /*
1022  * Returns NULL if the file can be opened and
1023  * is an ordinary file, otherwise an error message
1024  * (if it cannot be opened or is a directory, etc.)
1025  */
1026         public char *
1027 bad_file(filename)
1028         char *filename;
1029 {
1030         register char *m = NULL;
1031
1032         filename = shell_unquote(filename);
1033         if (!force_open && is_dir(filename))
1034         {
1035                 static char is_a_dir[] = " is a directory";
1036
1037                 m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
1038                         sizeof(char));
1039                 strcpy(m, filename);
1040                 strcat(m, is_a_dir);
1041         } else
1042         {
1043 #if HAVE_STAT
1044                 int r;
1045                 struct stat statbuf;
1046
1047                 r = stat(filename, &statbuf);
1048                 if (r < 0)
1049                 {
1050                         m = errno_message(filename);
1051                 } else if (force_open)
1052                 {
1053                         m = NULL;
1054                 } else if (!S_ISREG(statbuf.st_mode))
1055                 {
1056                         static char not_reg[] = " is not a regular file (use -f to see it)";
1057                         m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1058                                 sizeof(char));
1059                         strcpy(m, filename);
1060                         strcat(m, not_reg);
1061                 }
1062 #endif
1063         }
1064         free(filename);
1065         return (m);
1066 }
1067
1068 /*
1069  * Return the size of a file, as cheaply as possible.
1070  * In Unix, we can stat the file.
1071  */
1072         public POSITION
1073 filesize(f)
1074         int f;
1075 {
1076 #if HAVE_STAT
1077         struct stat statbuf;
1078
1079         if (fstat(f, &statbuf) >= 0)
1080                 return ((POSITION) statbuf.st_size);
1081 #else
1082 #ifdef _OSK
1083         long size;
1084
1085         if ((size = (long) _gs_size(f)) >= 0)
1086                 return ((POSITION) size);
1087 #endif
1088 #endif
1089         return (seek_filesize(f));
1090 }
1091
1092 /*
1093  *
1094  */
1095         public char *
1096 shell_coption()
1097 {
1098         return ("-c");
1099 }
1100
1101 /*
1102  * Return last component of a pathname.
1103  */
1104         public char *
1105 last_component(name)
1106         char *name;
1107 {
1108         char *slash;
1109
1110         for (slash = name + strlen(name);  slash > name; )
1111         {
1112                 --slash;
1113                 if (*slash == *PATHNAME_SEP || *slash == '/')
1114                         return (slash + 1);
1115         }
1116         return (name);
1117 }
1118