contrib/less-394/filename.c

   1 /*
   2  * Copyright (C) 1984-2005  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 IFILE curr_ifile;
  55 extern IFILE old_ifile;
  56 #if SPACES_IN_FILENAMES
  57 extern char openquote;
  58 extern char closequote;
  59 #endif
  60
  61 /*
  62  * Remove quotes around a filename.
  63  */
  64         public char *
  65 shell_unquote(str)
  66         char *str;
  67 {
  68         char *name;
  69         char *p;
  70
  71         name = p = (char *) ecalloc(strlen(str)+1, sizeof(char));
  72         if (*str == openquote)
  73         {
  74                 str++;
  75                 while (*str != '\0')
  76                 {
  77                         if (*str == closequote)
  78                         {
  79                                 if (str[1] != closequote)
  80                                         break;
  81                                 str++;
  82                         }
  83                         *p++ = *str++;
  84                 }
  85         } else
  86         {
  87                 char *esc = get_meta_escape();
  88                 int esclen = strlen(esc);
  89                 while (*str != '\0')
  90                 {
  91                         if (esclen > 0 && strncmp(str, esc, esclen) == 0)
  92                                 str += esclen;
  93                         *p++ = *str++;
  94                 }
  95         }
  96         *p = '\0';
  97         return (name);
  98 }
  99
 100 /*
 101  * Get the shell's escape character.
 102  */
 103         public char *
 104 get_meta_escape()
 105 {
 106         char *s;
 107
 108         s = lgetenv("LESSMETAESCAPE");
 109         if (s == NULL)
 110                 s = DEF_METAESCAPE;
 111         return (s);
 112 }
 113
 114 /*
 115  * Get the characters which the shell considers to be "metacharacters".
 116  */
 117         static char *
 118 metachars()
 119 {
 120         static char *mchars = NULL;
 121
 122         if (mchars == NULL)
 123         {
 124                 mchars = lgetenv("LESSMETACHARS");
 125                 if (mchars == NULL)
 126                         mchars = DEF_METACHARS;
 127         }
 128         return (mchars);
 129 }
 130
 131 /*
 132  * Is this a shell metacharacter?
 133  */
 134         static int
 135 metachar(c)
 136         char c;
 137 {
 138         return (strchr(metachars(), c) != NULL);
 139 }
 140
 141 /*
 142  * Insert a backslash before each metacharacter in a string.
 143  */
 144         public char *
 145 shell_quote(s)
 146         char *s;
 147 {
 148         char *p;
 149         char *newstr;
 150         int len;
 151         char *esc = get_meta_escape();
 152         int esclen = strlen(esc);
 153         int use_quotes = 0;
 154         int have_quotes = 0;
 155
 156         /*
 157          * Determine how big a string we need to allocate.
 158          */
 159         len = 1; /* Trailing null byte */
 160         for (p = s;  *p != '\0';  p++)
 161         {
 162                 len++;
 163                 if (*p == openquote || *p == closequote)
 164                         have_quotes = 1;
 165                 if (metachar(*p))
 166                 {
 167                         if (esclen == 0)
 168                         {
 169                                 /*
 170                                  * We've got a metachar, but this shell
 171                                  * doesn't support escape chars.  Use quotes.
 172                                  */
 173                                 use_quotes = 1;
 174                         } else
 175                         {
 176                                 /*
 177                                  * Allow space for the escape char.
 178                                  */
 179                                 len += esclen;
 180                         }
 181                 }
 182         }
 183         if (use_quotes)
 184         {
 185                 if (have_quotes)
 186                         /*
 187                          * We can't quote a string that contains quotes.
 188                          */
 189                         return (NULL);
 190                 len = strlen(s) + 3;
 191         }
 192         /*
 193          * Allocate and construct the new string.
 194          */
 195         newstr = p = (char *) ecalloc(len, sizeof(char));
 196         if (use_quotes)
 197         {
 198                 SNPRINTF3(newstr, len, "%c%s%c", openquote, s, closequote);
 199         } else
 200         {
 201                 while (*s != '\0')
 202                 {
 203                         if (metachar(*s))
 204                         {
 205                                 /*
 206                                  * Add the escape char.
 207                                  */
 208                                 strcpy(p, esc);
 209                                 p += esclen;
 210                         }
 211                         *p++ = *s++;
 212                 }
 213                 *p = '\0';
 214         }
 215         return (newstr);
 216 }
 217
 218 /*
 219  * Return a pathname that points to a specified file in a specified directory.
 220  * Return NULL if the file does not exist in the directory.
 221  */
 222         static char *
 223 dirfile(dirname, filename)
 224         char *dirname;
 225         char *filename;
 226 {
 227         char *pathname;
 228         char *qpathname;
 229         int len;
 230         int f;
 231
 232         if (dirname == NULL || *dirname == '\0')
 233                 return (NULL);
 234         /*
 235          * Construct the full pathname.
 236          */
 237         len= strlen(dirname) + strlen(filename) + 2;
 238         pathname = (char *) calloc(len, sizeof(char));
 239         if (pathname == NULL)
 240                 return (NULL);
 241         SNPRINTF3(pathname, len, "%s%s%s", dirname, PATHNAME_SEP, filename);
 242         /*
 243          * Make sure the file exists.
 244          */
 245         qpathname = shell_unquote(pathname);
 246         f = open(qpathname, OPEN_READ);
 247         if (f < 0)
 248         {
 249                 free(pathname);
 250                 pathname = NULL;
 251         } else
 252         {
 253                 close(f);
 254         }
 255         free(qpathname);
 256         return (pathname);
 257 }
 258
 259 /*
 260  * Return the full pathname of the given file in the "home directory".
 261  */
 262         public char *
 263 homefile(filename)
 264         char *filename;
 265 {
 266         register char *pathname;
 267
 268         /*
 269          * Try $HOME/filename.
 270          */
 271         pathname = dirfile(lgetenv("HOME"), filename);
 272         if (pathname != NULL)
 273                 return (pathname);
 274 #if OS2
 275         /*
 276          * Try $INIT/filename.
 277          */
 278         pathname = dirfile(lgetenv("INIT"), filename);
 279         if (pathname != NULL)
 280                 return (pathname);
 281 #endif
 282 #if MSDOS_COMPILER || OS2
 283         /*
 284          * Look for the file anywhere on search path.
 285          */
 286         pathname = (char *) calloc(_MAX_PATH, sizeof(char));
 287 #if MSDOS_COMPILER==DJGPPC
 288         {
 289                 char *res = searchpath(filename);
 290                 if (res == 0)
 291                         *pathname = '\0';
 292                 else
 293                         strcpy(pathname, res);
 294         }
 295 #else
 296         _searchenv(filename, "PATH", pathname);
 297 #endif
 298         if (*pathname != '\0')
 299                 return (pathname);
 300         free(pathname);
 301 #endif
 302         return (NULL);
 303 }
 304
 305 /*
 306  * Expand a string, substituting any "%" with the current filename,
 307  * and any "#" with the previous filename.
 308  * But a string of N "%"s is just replaced with N-1 "%"s.
 309  * Likewise for a string of N "#"s.
 310  * {{ This is a lot of work just to support % and #. }}
 311  */
 312         public char *
 313 fexpand(s)
 314         char *s;
 315 {
 316         register char *fr, *to;
 317         register int n;
 318         register char *e;
 319         IFILE ifile;
 320
 321 #define fchar_ifile(c) \
 322         ((c) == '%' ? curr_ifile : \
 323          (c) == '#' ? old_ifile : NULL_IFILE)
 324
 325         /*
 326          * Make one pass to see how big a buffer we
 327          * need to allocate for the expanded string.
 328          */
 329         n = 0;
 330         for (fr = s;  *fr != '\0';  fr++)
 331         {
 332                 switch (*fr)
 333                 {
 334                 case '%':
 335                 case '#':
 336                         if (fr > s && fr[-1] == *fr)
 337                         {
 338                                 /*
 339                                  * Second (or later) char in a string
 340                                  * of identical chars.  Treat as normal.
 341                                  */
 342                                 n++;
 343                         } else if (fr[1] != *fr)
 344                         {
 345                                 /*
 346                                  * Single char (not repeated).  Treat specially.
 347                                  */
 348                                 ifile = fchar_ifile(*fr);
 349                                 if (ifile == NULL_IFILE)
 350                                         n++;
 351                                 else
 352                                         n += strlen(get_filename(ifile));
 353                         }
 354                         /*
 355                          * Else it is the first char in a string of
 356                          * identical chars.  Just discard it.
 357                          */
 358                         break;
 359                 default:
 360                         n++;
 361                         break;
 362                 }
 363         }
 364
 365         e = (char *) ecalloc(n+1, sizeof(char));
 366
 367         /*
 368          * Now copy the string, expanding any "%" or "#".
 369          */
 370         to = e;
 371         for (fr = s;  *fr != '\0';  fr++)
 372         {
 373                 switch (*fr)
 374                 {
 375                 case '%':
 376                 case '#':
 377                         if (fr > s && fr[-1] == *fr)
 378                         {
 379                                 *to++ = *fr;
 380                         } else if (fr[1] != *fr)
 381                         {
 382                                 ifile = fchar_ifile(*fr);
 383                                 if (ifile == NULL_IFILE)
 384                                         *to++ = *fr;
 385                                 else
 386                                 {
 387                                         strcpy(to, get_filename(ifile));
 388                                         to += strlen(to);
 389                                 }
 390                         }
 391                         break;
 392                 default:
 393                         *to++ = *fr;
 394                         break;
 395                 }
 396         }
 397         *to = '\0';
 398         return (e);
 399 }
 400
 401 #if TAB_COMPLETE_FILENAME
 402
 403 /*
 404  * Return a blank-separated list of filenames which "complete"
 405  * the given string.
 406  */
 407         public char *
 408 fcomplete(s)
 409         char *s;
 410 {
 411         char *fpat;
 412         char *qs;
 413
 414         if (secure)
 415                 return (NULL);
 416         /*
 417          * Complete the filename "s" by globbing "s*".
 418          */
 419 #if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
 420         /*
 421          * But in DOS, we have to glob "s*.*".
 422          * But if the final component of the filename already has
 423          * a dot in it, just do "s*".
 424          * (Thus, "FILE" is globbed as "FILE*.*",
 425          *  but "FILE.A" is globbed as "FILE.A*").
 426          */
 427         {
 428                 char *slash;
 429                 int len;
 430                 for (slash = s+strlen(s)-1;  slash > s;  slash--)
 431                         if (*slash == *PATHNAME_SEP || *slash == '/')
 432                                 break;
 433                 len = strlen(s) + 4;
 434                 fpat = (char *) ecalloc(len, sizeof(char));
 435                 if (strchr(slash, '.') == NULL)
 436                         SNPRINTF1(fpat, len, "%s*.*", s);
 437                 else
 438                         SNPRINTF1(fpat, len, "%s*", s);
 439         }
 440 #else
 441         {
 442         int len = strlen(s) + 2;
 443         fpat = (char *) ecalloc(len, sizeof(char));
 444         SNPRINTF1(fpat, len, "%s*", s);
 445         }
 446 #endif
 447         qs = lglob(fpat);
 448         s = shell_unquote(qs);
 449         if (strcmp(s,fpat) == 0)
 450         {
 451                 /*
 452                  * The filename didn't expand.
 453                  */
 454                 free(qs);
 455                 qs = NULL;
 456         }
 457         free(s);
 458         free(fpat);
 459         return (qs);
 460 }
 461 #endif
 462
 463 /*
 464  * Try to determine if a file is "binary".
 465  * This is just a guess, and we need not try too hard to make it accurate.
 466  */
 467         public int
 468 bin_file(f)
 469         int f;
 470 {
 471         int i;
 472         int n;
 473         unsigned char data[64];
 474
 475         if (!seekable(f))
 476                 return (0);
 477         if (lseek(f, (off_t)0, 0) == BAD_LSEEK)
 478                 return (0);
 479         n = read(f, data, sizeof(data));
 480         for (i = 0;  i < n;  i++)
 481                 if (binary_char(data[i]))
 482                         return (1);
 483         return (0);
 484 }
 485
 486 /*
 487  * Try to determine the size of a file by seeking to the end.
 488  */
 489         static POSITION
 490 seek_filesize(f)
 491         int f;
 492 {
 493         off_t spos;
 494
 495         spos = lseek(f, (off_t)0, 2);
 496         if (spos == BAD_LSEEK)
 497                 return (NULL_POSITION);
 498         return ((POSITION) spos);
 499 }
 500
 501 /*
 502  * Read a string from a file.
 503  * Return a pointer to the string in memory.
 504  */
 505         static char *
 506 readfd(fd)
 507         FILE *fd;
 508 {
 509         int len;
 510         int ch;
 511         char *buf;
 512         char *p;
 513
 514         /*
 515          * Make a guess about how many chars in the string
 516          * and allocate a buffer to hold it.
 517          */
 518         len = 100;
 519         buf = (char *) ecalloc(len, sizeof(char));
 520         for (p = buf;  ;  p++)
 521         {
 522                 if ((ch = getc(fd)) == '\n' || ch == EOF)
 523                         break;
 524                 if (p - buf >= len-1)
 525                 {
 526                         /*
 527                          * The string is too big to fit in the buffer we have.
 528                          * Allocate a new buffer, twice as big.
 529                          */
 530                         len *= 2;
 531                         *p = '\0';
 532                         p = (char *) ecalloc(len, sizeof(char));
 533                         strcpy(p, buf);
 534                         free(buf);
 535                         buf = p;
 536                         p = buf + strlen(buf);
 537                 }
 538                 *p = ch;
 539         }
 540         *p = '\0';
 541         return (buf);
 542 }
 543
 544
 545
 546 #if HAVE_POPEN
 547
 548 FILE *popen();
 549
 550 /*
 551  * Execute a shell command.
 552  * Return a pointer to a pipe connected to the shell command's standard output.
 553  */
 554         static FILE *
 555 shellcmd(cmd)
 556         char *cmd;
 557 {
 558         FILE *fd;
 559
 560 #if HAVE_SHELL
 561         char *shell;
 562
 563         shell = lgetenv("SHELL");
 564         if (shell != NULL && *shell != '\0')
 565         {
 566                 char *scmd;
 567                 char *esccmd;
 568
 569                 /*
 570                  * Read the output of <$SHELL -c cmd>.
 571                  * Escape any metacharacters in the command.
 572                  */
 573                 esccmd = shell_quote(cmd);
 574                 if (esccmd == NULL)
 575                 {
 576                         fd = popen(cmd, "r");
 577                 } else
 578                 {
 579                         int len = strlen(shell) + strlen(esccmd) + 5;
 580                         scmd = (char *) ecalloc(len, sizeof(char));
 581                         SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
 582                         free(esccmd);
 583                         fd = popen(scmd, "r");
 584                         free(scmd);
 585                 }
 586         } else
 587 #endif
 588         {
 589                 fd = popen(cmd, "r");
 590         }
 591         /*
 592          * Redirection in `popen' might have messed with the
 593          * standard devices.  Restore binary input mode.
 594          */
 595         SET_BINARY(0);
 596         return (fd);
 597 }
 598
 599 #endif /* HAVE_POPEN */
 600
 601
 602 /*
 603  * Expand a filename, doing any system-specific metacharacter substitutions.
 604  */
 605         public char *
 606 lglob(filename)
 607         char *filename;
 608 {
 609         char *gfilename;
 610         char *ofilename;
 611
 612         ofilename = fexpand(filename);
 613         if (secure)
 614                 return (ofilename);
 615         filename = shell_unquote(ofilename);
 616
 617 #ifdef DECL_GLOB_LIST
 618 {
 619         /*
 620          * The globbing function returns a list of names.
 621          */
 622         int length;
 623         char *p;
 624         char *qfilename;
 625         DECL_GLOB_LIST(list)
 626
 627         GLOB_LIST(filename, list);
 628         if (GLOB_LIST_FAILED(list))
 629         {
 630                 free(filename);
 631                 return (ofilename);
 632         }
 633         length = 1; /* Room for trailing null byte */
 634         for (SCAN_GLOB_LIST(list, p))
 635         {
 636                 INIT_GLOB_LIST(list, p);
 637                 qfilename = shell_quote(p);
 638                 if (qfilename != NULL)
 639                 {
 640                         length += strlen(qfilename) + 1;
 641                         free(qfilename);
 642                 }
 643         }
 644         gfilename = (char *) ecalloc(length, sizeof(char));
 645         for (SCAN_GLOB_LIST(list, p))
 646         {
 647                 INIT_GLOB_LIST(list, p);
 648                 qfilename = shell_quote(p);
 649                 if (qfilename != NULL)
 650                 {
 651                         sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
 652                         free(qfilename);
 653                 }
 654         }
 655         /*
 656          * Overwrite the final trailing space with a null terminator.
 657          */
 658         *--p = '\0';
 659         GLOB_LIST_DONE(list);
 660 }
 661 #else
 662 #ifdef DECL_GLOB_NAME
 663 {
 664         /*
 665          * The globbing function returns a single name, and
 666          * is called multiple times to walk thru all names.
 667          */
 668         register char *p;
 669         register int len;
 670         register int n;
 671         char *pathname;
 672         char *qpathname;
 673         DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
 674
 675         GLOB_FIRST_NAME(filename, &fnd, handle);
 676         if (GLOB_FIRST_FAILED(handle))
 677         {
 678                 free(filename);
 679                 return (ofilename);
 680         }
 681
 682         _splitpath(filename, drive, dir, fname, ext);
 683         len = 100;
 684         gfilename = (char *) ecalloc(len, sizeof(char));
 685         p = gfilename;
 686         do {
 687                 n = strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1;
 688                 pathname = (char *) ecalloc(n, sizeof(char));
 689                 SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
 690                 qpathname = shell_quote(pathname);
 691                 free(pathname);
 692                 if (qpathname != NULL)
 693                 {
 694                         n = strlen(qpathname);
 695                         while (p - gfilename + n + 2 >= len)
 696                         {
 697                                 /*
 698                                  * No room in current buffer.
 699                                  * Allocate a bigger one.
 700                                  */
 701                                 len *= 2;
 702                                 *p = '\0';
 703                                 p = (char *) ecalloc(len, sizeof(char));
 704                                 strcpy(p, gfilename);
 705                                 free(gfilename);
 706                                 gfilename = p;
 707                                 p = gfilename + strlen(gfilename);
 708                         }
 709                         strcpy(p, qpathname);
 710                         free(qpathname);
 711                         p += n;
 712                         *p++ = ' ';
 713                 }
 714         } while (GLOB_NEXT_NAME(handle, &fnd) == 0);
 715
 716         /*
 717          * Overwrite the final trailing space with a null terminator.
 718          */
 719         *--p = '\0';
 720         GLOB_NAME_DONE(handle);
 721 }
 722 #else
 723 #if HAVE_POPEN
 724 {
 725         /*
 726          * We get the shell to glob the filename for us by passing
 727          * an "echo" command to the shell and reading its output.
 728          */
 729         FILE *fd;
 730         char *s;
 731         char *lessecho;
 732         char *cmd;
 733         char *esc;
 734         int len;
 735
 736         esc = get_meta_escape();
 737         if (strlen(esc) == 0)
 738                 esc = "-";
 739         esc = shell_quote(esc);
 740         if (esc == NULL)
 741         {
 742                 free(filename);
 743                 return (ofilename);
 744         }
 745         lessecho = lgetenv("LESSECHO");
 746         if (lessecho == NULL || *lessecho == '\0')
 747                 lessecho = "lessecho";
 748         /*
 749          * Invoke lessecho, and read its output (a globbed list of filenames).
 750          */
 751         len = strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24;
 752         cmd = (char *) ecalloc(len, sizeof(char));
 753         SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
 754         free(esc);
 755         for (s = metachars();  *s != '\0';  s++)
 756                 sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
 757         sprintf(cmd + strlen(cmd), "-- %s", ofilename);
 758         fd = shellcmd(cmd);
 759         free(cmd);
 760         if (fd == NULL)
 761         {
 762                 /*
 763                  * Cannot create the pipe.
 764                  * Just return the original (fexpanded) filename.
 765                  */
 766                 free(filename);
 767                 return (ofilename);
 768         }
 769         gfilename = readfd(fd);
 770         pclose(fd);
 771         if (*gfilename == '\0')
 772         {
 773                 free(gfilename);
 774                 free(filename);
 775                 return (ofilename);
 776         }
 777 }
 778 #else
 779         /*
 780          * No globbing functions at all.  Just use the fexpanded filename.
 781          */
 782         gfilename = save(filename);
 783 #endif
 784 #endif
 785 #endif
 786         free(filename);
 787         free(ofilename);
 788         return (gfilename);
 789 }
 790
 791 /*
 792  * See if we should open a "replacement file"
 793  * instead of the file we're about to open.
 794  */
 795         public char *
 796 open_altfile(filename, pf, pfd)
 797         char *filename;
 798         int *pf;
 799         void **pfd;
 800 {
 801 #if !HAVE_POPEN
 802         return (NULL);
 803 #else
 804         char *lessopen;
 805         char *cmd;
 806         int len;
 807         FILE *fd;
 808 #if HAVE_FILENO
 809         int returnfd = 0;
 810 #endif
 811
 812         if (!use_lessopen || secure)
 813                 return (NULL);
 814         ch_ungetchar(-1);
 815         if ((lessopen = lgetenv("LESSOPEN")) == NULL)
 816                 return (NULL);
 817         if (strcmp(filename, "-") == 0)
 818                 return (NULL);
 819         if (*lessopen == '|')
 820         {
 821                 /*
 822                  * If LESSOPEN starts with a |, it indicates
 823                  * a "pipe preprocessor".
 824                  */
 825 #if HAVE_FILENO
 826                 lessopen++;
 827                 returnfd = 1;
 828 #else
 829                 error("LESSOPEN pipe is not supported", NULL_PARG);
 830                 return (NULL);
 831 #endif
 832         }
 833
 834         len = strlen(lessopen) + strlen(filename) + 2;
 835         cmd = (char *) ecalloc(len, sizeof(char));
 836         SNPRINTF1(cmd, len, lessopen, filename);
 837         fd = shellcmd(cmd);
 838         free(cmd);
 839         if (fd == NULL)
 840         {
 841                 /*
 842                  * Cannot create the pipe.
 843                  */
 844                 return (NULL);
 845         }
 846 #if HAVE_FILENO
 847         if (returnfd)
 848         {
 849                 int f;
 850                 char c;
 851
 852                 /*
 853                  * Read one char to see if the pipe will produce any data.
 854                  * If it does, push the char back on the pipe.
 855                  */
 856                 f = fileno(fd);
 857                 SET_BINARY(f);
 858                 if (read(f, &c, 1) != 1)
 859                 {
 860                         /*
 861                          * Pipe is empty.  This means there is no alt file.
 862                          */
 863                         pclose(fd);
 864                         return (NULL);
 865                 }
 866                 ch_ungetchar(c);
 867                 *pfd = (void *) fd;
 868                 *pf = f;
 869                 return (save("-"));
 870         }
 871 #endif
 872         cmd = readfd(fd);
 873         pclose(fd);
 874         if (*cmd == '\0')
 875                 /*
 876                  * Pipe is empty.  This means there is no alt file.
 877                  */
 878                 return (NULL);
 879         return (cmd);
 880 #endif /* HAVE_POPEN */
 881 }
 882
 883 /*
 884  * Close a replacement file.
 885  */
 886         public void
 887 close_altfile(altfilename, filename, pipefd)
 888         char *altfilename;
 889         char *filename;
 890         void *pipefd;
 891 {
 892 #if HAVE_POPEN
 893         char *lessclose;
 894         FILE *fd;
 895         char *cmd;
 896         int len;
 897
 898         if (secure)
 899                 return;
 900         if (pipefd != NULL)
 901         {
 902 #if OS2
 903                 /*
 904                  * The pclose function of OS/2 emx sometimes fails.
 905                  * Send SIGINT to the piped process before closing it.
 906                  */
 907                 kill(((FILE*)pipefd)->_pid, SIGINT);
 908 #endif
 909                 pclose((FILE*) pipefd);
 910         }
 911         if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
 912                 return;
 913         len = strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2;
 914         cmd = (char *) ecalloc(len, sizeof(char));
 915         SNPRINTF2(cmd, len, lessclose, filename, altfilename);
 916         fd = shellcmd(cmd);
 917         free(cmd);
 918         if (fd != NULL)
 919                 pclose(fd);
 920 #endif
 921 }
 922
 923 /*
 924  * Is the specified file a directory?
 925  */
 926         public int
 927 is_dir(filename)
 928         char *filename;
 929 {
 930         int isdir = 0;
 931
 932         filename = shell_unquote(filename);
 933 #if HAVE_STAT
 934 {
 935         int r;
 936         struct stat statbuf;
 937
 938         r = stat(filename, &statbuf);
 939         isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
 940 }
 941 #else
 942 #ifdef _OSK
 943 {
 944         register int f;
 945
 946         f = open(filename, S_IREAD | S_IFDIR);
 947         if (f >= 0)
 948                 close(f);
 949         isdir = (f >= 0);
 950 }
 951 #endif
 952 #endif
 953         free(filename);
 954         return (isdir);
 955 }
 956
 957 /*
 958  * Returns NULL if the file can be opened and
 959  * is an ordinary file, otherwise an error message
 960  * (if it cannot be opened or is a directory, etc.)
 961  */
 962         public char *
 963 bad_file(filename)
 964         char *filename;
 965 {
 966         register char *m = NULL;
 967
 968         filename = shell_unquote(filename);
 969         if (is_dir(filename))
 970         {
 971                 static char is_a_dir[] = " is a directory";
 972
 973                 m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
 974                         sizeof(char));
 975                 strcpy(m, filename);
 976                 strcat(m, is_a_dir);
 977         } else
 978         {
 979 #if HAVE_STAT
 980                 int r;
 981                 struct stat statbuf;
 982
 983                 r = stat(filename, &statbuf);
 984                 if (r < 0)
 985                 {
 986                         m = errno_message(filename);
 987                 } else if (force_open)
 988                 {
 989                         m = NULL;
 990                 } else if (!S_ISREG(statbuf.st_mode))
 991                 {
 992                         static char not_reg[] = " is not a regular file (use -f to see it)";
 993                         m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
 994                                 sizeof(char));
 995                         strcpy(m, filename);
 996                         strcat(m, not_reg);
 997                 }
 998 #endif
 999         }
1000         free(filename);
1001         return (m);
1002 }
1003
1004 /*
1005  * Return the size of a file, as cheaply as possible.
1006  * In Unix, we can stat the file.
1007  */
1008         public POSITION
1009 filesize(f)
1010         int f;
1011 {
1012 #if HAVE_STAT
1013         struct stat statbuf;
1014
1015         if (fstat(f, &statbuf) >= 0)
1016                 return ((POSITION) statbuf.st_size);
1017 #else
1018 #ifdef _OSK
1019         long size;
1020
1021         if ((size = (long) _gs_size(f)) >= 0)
1022                 return ((POSITION) size);
1023 #endif
1024 #endif
1025         return (seek_filesize(f));
1026 }
1027
1028 /*
1029  *
1030  */
1031         public char *
1032 shell_coption()
1033 {
1034         return ("-c");
1035 }