xref: /freebsd/contrib/less/filename.c (revision 4ca50eab86aec8001978a612a42f9ae8388eceab)
1 /*
2  * Copyright (C) 1984-2015  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(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 = (int) 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(void)
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(void)
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(char c)
136 {
137 	return (strchr(metachars(), c) != NULL);
138 }
139 
140 /*
141  * Insert a backslash before each metacharacter in a string.
142  */
143 	public char *
144 shell_quote(char *s)
145 {
146 	char *p;
147 	char *newstr;
148 	int len;
149 	char *esc = get_meta_escape();
150 	int esclen = (int) strlen(esc);
151 	int use_quotes = 0;
152 	int have_quotes = 0;
153 
154 	/*
155 	 * Determine how big a string we need to allocate.
156 	 */
157 	len = 1; /* Trailing null byte */
158 	for (p = s;  *p != '\0';  p++)
159 	{
160 		len++;
161 		if (*p == openquote || *p == closequote)
162 			have_quotes = 1;
163 		if (metachar(*p))
164 		{
165 			if (esclen == 0)
166 			{
167 				/*
168 				 * We've got a metachar, but this shell
169 				 * doesn't support escape chars.  Use quotes.
170 				 */
171 				use_quotes = 1;
172 			} else
173 			{
174 				/*
175 				 * Allow space for the escape char.
176 				 */
177 				len += esclen;
178 			}
179 		}
180 	}
181 	if (use_quotes)
182 	{
183 		if (have_quotes)
184 			/*
185 			 * We can't quote a string that contains quotes.
186 			 */
187 			return (NULL);
188 		len = (int) strlen(s) + 3;
189 	}
190 	/*
191 	 * Allocate and construct the new string.
192 	 */
193 	newstr = p = (char *) ecalloc(len, sizeof(char));
194 	if (use_quotes)
195 	{
196 		SNPRINTF3(newstr, len, "%c%s%c", openquote, s, closequote);
197 	} else
198 	{
199 		while (*s != '\0')
200 		{
201 			if (metachar(*s))
202 			{
203 				/*
204 				 * Add the escape char.
205 				 */
206 				strcpy(p, esc);
207 				p += esclen;
208 			}
209 			*p++ = *s++;
210 		}
211 		*p = '\0';
212 	}
213 	return (newstr);
214 }
215 
216 /*
217  * Return a pathname that points to a specified file in a specified directory.
218  * Return NULL if the file does not exist in the directory.
219  */
220 	static char *
221 dirfile(char *dirname, char *filename)
222 {
223 	char *pathname;
224 	char *qpathname;
225 	int len;
226 	int f;
227 
228 	if (dirname == NULL || *dirname == '\0')
229 		return (NULL);
230 	/*
231 	 * Construct the full pathname.
232 	 */
233 	len = (int) (strlen(dirname) + strlen(filename) + 2);
234 	pathname = (char *) calloc(len, sizeof(char));
235 	if (pathname == NULL)
236 		return (NULL);
237 	SNPRINTF3(pathname, len, "%s%s%s", dirname, PATHNAME_SEP, filename);
238 	/*
239 	 * Make sure the file exists.
240 	 */
241 	qpathname = shell_unquote(pathname);
242 	f = open(qpathname, OPEN_READ);
243 	if (f < 0)
244 	{
245 		free(pathname);
246 		pathname = NULL;
247 	} else
248 	{
249 		close(f);
250 	}
251 	free(qpathname);
252 	return (pathname);
253 }
254 
255 /*
256  * Return the full pathname of the given file in the "home directory".
257  */
258 	public char *
259 homefile(char *filename)
260 {
261 	char *pathname;
262 
263 	/*
264 	 * Try $HOME/filename.
265 	 */
266 	pathname = dirfile(lgetenv("HOME"), filename);
267 	if (pathname != NULL)
268 		return (pathname);
269 #if OS2
270 	/*
271 	 * Try $INIT/filename.
272 	 */
273 	pathname = dirfile(lgetenv("INIT"), filename);
274 	if (pathname != NULL)
275 		return (pathname);
276 #endif
277 #if MSDOS_COMPILER || OS2
278 	/*
279 	 * Look for the file anywhere on search path.
280 	 */
281 	pathname = (char *) calloc(_MAX_PATH, sizeof(char));
282 #if MSDOS_COMPILER==DJGPPC
283 	{
284 		char *res = searchpath(filename);
285 		if (res == 0)
286 			*pathname = '\0';
287 		else
288 			strcpy(pathname, res);
289 	}
290 #else
291 	_searchenv(filename, "PATH", pathname);
292 #endif
293 	if (*pathname != '\0')
294 		return (pathname);
295 	free(pathname);
296 #endif
297 	return (NULL);
298 }
299 
300 /*
301  * Expand a string, substituting any "%" with the current filename,
302  * and any "#" with the previous filename.
303  * But a string of N "%"s is just replaced with N-1 "%"s.
304  * Likewise for a string of N "#"s.
305  * {{ This is a lot of work just to support % and #. }}
306  */
307 	public char *
308 fexpand(char *s)
309 {
310 	char *fr, *to;
311 	int n;
312 	char *e;
313 	IFILE ifile;
314 
315 #define	fchar_ifile(c) \
316 	((c) == '%' ? curr_ifile : \
317 	 (c) == '#' ? old_ifile : NULL_IFILE)
318 
319 	/*
320 	 * Make one pass to see how big a buffer we
321 	 * need to allocate for the expanded string.
322 	 */
323 	n = 0;
324 	for (fr = s;  *fr != '\0';  fr++)
325 	{
326 		switch (*fr)
327 		{
328 		case '%':
329 		case '#':
330 			if (fr > s && fr[-1] == *fr)
331 			{
332 				/*
333 				 * Second (or later) char in a string
334 				 * of identical chars.  Treat as normal.
335 				 */
336 				n++;
337 			} else if (fr[1] != *fr)
338 			{
339 				/*
340 				 * Single char (not repeated).  Treat specially.
341 				 */
342 				ifile = fchar_ifile(*fr);
343 				if (ifile == NULL_IFILE)
344 					n++;
345 				else
346 					n += (int) strlen(get_filename(ifile));
347 			}
348 			/*
349 			 * Else it is the first char in a string of
350 			 * identical chars.  Just discard it.
351 			 */
352 			break;
353 		default:
354 			n++;
355 			break;
356 		}
357 	}
358 
359 	e = (char *) ecalloc(n+1, sizeof(char));
360 
361 	/*
362 	 * Now copy the string, expanding any "%" or "#".
363 	 */
364 	to = e;
365 	for (fr = s;  *fr != '\0';  fr++)
366 	{
367 		switch (*fr)
368 		{
369 		case '%':
370 		case '#':
371 			if (fr > s && fr[-1] == *fr)
372 			{
373 				*to++ = *fr;
374 			} else if (fr[1] != *fr)
375 			{
376 				ifile = fchar_ifile(*fr);
377 				if (ifile == NULL_IFILE)
378 					*to++ = *fr;
379 				else
380 				{
381 					strcpy(to, get_filename(ifile));
382 					to += strlen(to);
383 				}
384 			}
385 			break;
386 		default:
387 			*to++ = *fr;
388 			break;
389 		}
390 	}
391 	*to = '\0';
392 	return (e);
393 }
394 
395 
396 #if TAB_COMPLETE_FILENAME
397 
398 /*
399  * Return a blank-separated list of filenames which "complete"
400  * the given string.
401  */
402 	public char *
403 fcomplete(char *s)
404 {
405 	char *fpat;
406 	char *qs;
407 
408 	if (secure)
409 		return (NULL);
410 	/*
411 	 * Complete the filename "s" by globbing "s*".
412 	 */
413 #if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
414 	/*
415 	 * But in DOS, we have to glob "s*.*".
416 	 * But if the final component of the filename already has
417 	 * a dot in it, just do "s*".
418 	 * (Thus, "FILE" is globbed as "FILE*.*",
419 	 *  but "FILE.A" is globbed as "FILE.A*").
420 	 */
421 	{
422 		char *slash;
423 		int len;
424 		for (slash = s+strlen(s)-1;  slash > s;  slash--)
425 			if (*slash == *PATHNAME_SEP || *slash == '/')
426 				break;
427 		len = (int) strlen(s) + 4;
428 		fpat = (char *) ecalloc(len, sizeof(char));
429 		if (strchr(slash, '.') == NULL)
430 			SNPRINTF1(fpat, len, "%s*.*", s);
431 		else
432 			SNPRINTF1(fpat, len, "%s*", s);
433 	}
434 #else
435 	{
436 	int len = (int) strlen(s) + 2;
437 	fpat = (char *) ecalloc(len, sizeof(char));
438 	SNPRINTF1(fpat, len, "%s*", s);
439 	}
440 #endif
441 	qs = lglob(fpat);
442 	s = shell_unquote(qs);
443 	if (strcmp(s,fpat) == 0)
444 	{
445 		/*
446 		 * The filename didn't expand.
447 		 */
448 		free(qs);
449 		qs = NULL;
450 	}
451 	free(s);
452 	free(fpat);
453 	return (qs);
454 }
455 #endif
456 
457 /*
458  * Try to determine if a file is "binary".
459  * This is just a guess, and we need not try too hard to make it accurate.
460  */
461 	public int
462 bin_file(int f)
463 {
464 	int n;
465 	int bin_count = 0;
466 	char data[256];
467 	constant char* p;
468 	char* pend;
469 
470 	if (!seekable(f))
471 		return (0);
472 	if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
473 		return (0);
474 	n = read(f, data, sizeof(data));
475 	if (n <= 0)
476 		return (0);
477 	if (utf_mode)
478 	{
479 		bin_count = utf_bin_count(data, n);
480 	} else
481 	{
482 		pend = &data[n];
483 		for (p = data;  p < pend;  )
484 		{
485 			LWCHAR c = step_char(&p, +1, pend);
486 			if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
487 			{
488 				do {
489 					c = step_char(&p, +1, pend);
490 				} while (p < pend && is_ansi_middle(c));
491 			} else if (binary_char(c))
492 				bin_count++;
493 		}
494 	}
495 	/*
496 	 * Call it a binary file if there are more than 5 binary characters
497 	 * in the first 256 bytes of the file.
498 	 */
499 	return (bin_count > 5);
500 }
501 
502 /*
503  * Try to determine the size of a file by seeking to the end.
504  */
505 	static POSITION
506 seek_filesize(int f)
507 {
508 	off_t spos;
509 
510 	spos = lseek(f, (off_t)0, SEEK_END);
511 	if (spos == BAD_LSEEK)
512 		return (NULL_POSITION);
513 	return ((POSITION) spos);
514 }
515 
516 /*
517  * Read a string from a file.
518  * Return a pointer to the string in memory.
519  */
520 	static char *
521 readfd(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(char *cmd)
570 {
571 	FILE *fd;
572 
573 #if HAVE_SHELL
574 	char *shell;
575 
576 	shell = lgetenv("SHELL");
577 	if (shell != NULL && *shell != '\0')
578 	{
579 		char *scmd;
580 		char *esccmd;
581 
582 		/*
583 		 * Read the output of <$SHELL -c cmd>.
584 		 * Escape any metacharacters in the command.
585 		 */
586 		esccmd = shell_quote(cmd);
587 		if (esccmd == NULL)
588 		{
589 			fd = popen(cmd, "r");
590 		} else
591 		{
592 			int len = (int) (strlen(shell) + strlen(esccmd) + 5);
593 			scmd = (char *) ecalloc(len, sizeof(char));
594 			SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
595 			free(esccmd);
596 			fd = popen(scmd, "r");
597 			free(scmd);
598 		}
599 	} else
600 #endif
601 	{
602 		fd = popen(cmd, "r");
603 	}
604 	/*
605 	 * Redirection in `popen' might have messed with the
606 	 * standard devices.  Restore binary input mode.
607 	 */
608 	SET_BINARY(0);
609 	return (fd);
610 }
611 
612 #endif /* HAVE_POPEN */
613 
614 
615 /*
616  * Expand a filename, doing any system-specific metacharacter substitutions.
617  */
618 	public char *
619 lglob(char *filename)
620 {
621 	char *gfilename;
622 	char *ofilename;
623 
624 	ofilename = fexpand(filename);
625 	if (secure)
626 		return (ofilename);
627 	filename = shell_unquote(ofilename);
628 
629 #ifdef DECL_GLOB_LIST
630 {
631 	/*
632 	 * The globbing function returns a list of names.
633 	 */
634 	int length;
635 	char *p;
636 	char *qfilename;
637 	DECL_GLOB_LIST(list)
638 
639 	GLOB_LIST(filename, list);
640 	if (GLOB_LIST_FAILED(list))
641 	{
642 		free(filename);
643 		return (ofilename);
644 	}
645 	length = 1; /* Room for trailing null byte */
646 	for (SCAN_GLOB_LIST(list, p))
647 	{
648 		INIT_GLOB_LIST(list, p);
649 		qfilename = shell_quote(p);
650 		if (qfilename != NULL)
651 		{
652 	  		length += strlen(qfilename) + 1;
653 			free(qfilename);
654 		}
655 	}
656 	gfilename = (char *) ecalloc(length, sizeof(char));
657 	for (SCAN_GLOB_LIST(list, p))
658 	{
659 		INIT_GLOB_LIST(list, p);
660 		qfilename = shell_quote(p);
661 		if (qfilename != NULL)
662 		{
663 			sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
664 			free(qfilename);
665 		}
666 	}
667 	/*
668 	 * Overwrite the final trailing space with a null terminator.
669 	 */
670 	*--p = '\0';
671 	GLOB_LIST_DONE(list);
672 }
673 #else
674 #ifdef DECL_GLOB_NAME
675 {
676 	/*
677 	 * The globbing function returns a single name, and
678 	 * is called multiple times to walk thru all names.
679 	 */
680 	char *p;
681 	int len;
682 	int n;
683 	char *pathname;
684 	char *qpathname;
685 	DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
686 
687 	GLOB_FIRST_NAME(filename, &fnd, handle);
688 	if (GLOB_FIRST_FAILED(handle))
689 	{
690 		free(filename);
691 		return (ofilename);
692 	}
693 
694 	_splitpath(filename, drive, dir, fname, ext);
695 	len = 100;
696 	gfilename = (char *) ecalloc(len, sizeof(char));
697 	p = gfilename;
698 	do {
699 		n = (int) (strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1);
700 		pathname = (char *) ecalloc(n, sizeof(char));
701 		SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
702 		qpathname = shell_quote(pathname);
703 		free(pathname);
704 		if (qpathname != NULL)
705 		{
706 			n = (int) strlen(qpathname);
707 			while (p - gfilename + n + 2 >= len)
708 			{
709 				/*
710 				 * No room in current buffer.
711 				 * Allocate a bigger one.
712 				 */
713 				len *= 2;
714 				*p = '\0';
715 				p = (char *) ecalloc(len, sizeof(char));
716 				strcpy(p, gfilename);
717 				free(gfilename);
718 				gfilename = p;
719 				p = gfilename + strlen(gfilename);
720 			}
721 			strcpy(p, qpathname);
722 			free(qpathname);
723 			p += n;
724 			*p++ = ' ';
725 		}
726 	} while (GLOB_NEXT_NAME(handle, &fnd) == 0);
727 
728 	/*
729 	 * Overwrite the final trailing space with a null terminator.
730 	 */
731 	*--p = '\0';
732 	GLOB_NAME_DONE(handle);
733 }
734 #else
735 #if HAVE_POPEN
736 {
737 	/*
738 	 * We get the shell to glob the filename for us by passing
739 	 * an "echo" command to the shell and reading its output.
740 	 */
741 	FILE *fd;
742 	char *s;
743 	char *lessecho;
744 	char *cmd;
745 	char *esc;
746 	int len;
747 
748 	esc = get_meta_escape();
749 	if (strlen(esc) == 0)
750 		esc = "-";
751 	esc = shell_quote(esc);
752 	if (esc == NULL)
753 	{
754 		free(filename);
755 		return (ofilename);
756 	}
757 	lessecho = lgetenv("LESSECHO");
758 	if (lessecho == NULL || *lessecho == '\0')
759 		lessecho = "lessecho";
760 	/*
761 	 * Invoke lessecho, and read its output (a globbed list of filenames).
762 	 */
763 	len = (int) (strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24);
764 	cmd = (char *) ecalloc(len, sizeof(char));
765 	SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
766 	free(esc);
767 	for (s = metachars();  *s != '\0';  s++)
768 		sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
769 	sprintf(cmd + strlen(cmd), "-- %s", ofilename);
770 	fd = shellcmd(cmd);
771 	free(cmd);
772 	if (fd == NULL)
773 	{
774 		/*
775 		 * Cannot create the pipe.
776 		 * Just return the original (fexpanded) filename.
777 		 */
778 		free(filename);
779 		return (ofilename);
780 	}
781 	gfilename = readfd(fd);
782 	pclose(fd);
783 	if (*gfilename == '\0')
784 	{
785 		free(gfilename);
786 		free(filename);
787 		return (ofilename);
788 	}
789 }
790 #else
791 	/*
792 	 * No globbing functions at all.  Just use the fexpanded filename.
793 	 */
794 	gfilename = save(filename);
795 #endif
796 #endif
797 #endif
798 	free(filename);
799 	free(ofilename);
800 	return (gfilename);
801 }
802 
803 /*
804  * Return number of %s escapes in a string.
805  * Return a large number if there are any other % escapes besides %s.
806  */
807 	static int
808 num_pct_s(char *lessopen)
809 {
810 	int num = 0;
811 
812 	while (*lessopen != '\0')
813 	{
814 		if (*lessopen == '%')
815 		{
816 			if (lessopen[1] == '%')
817 				++lessopen;
818 			else if (lessopen[1] == 's')
819 				++num;
820 			else
821 				return (999);
822 		}
823 		++lessopen;
824 	}
825 	return (num);
826 }
827 
828 /*
829  * See if we should open a "replacement file"
830  * instead of the file we're about to open.
831  */
832 	public char *
833 open_altfile(char *filename, int *pf, void **pfd)
834 {
835 #if !HAVE_POPEN
836 	return (NULL);
837 #else
838 	char *lessopen;
839 	char *cmd;
840 	int len;
841 	FILE *fd;
842 #if HAVE_FILENO
843 	int returnfd = 0;
844 #endif
845 
846 	if (!use_lessopen || secure)
847 		return (NULL);
848 	ch_ungetchar(-1);
849 	if ((lessopen = lgetenv("LESSOPEN")) == NULL)
850 		return (NULL);
851 	while (*lessopen == '|')
852 	{
853 		/*
854 		 * If LESSOPEN starts with a |, it indicates
855 		 * a "pipe preprocessor".
856 		 */
857 #if !HAVE_FILENO
858 		error("LESSOPEN pipe is not supported", NULL_PARG);
859 		return (NULL);
860 #else
861 		lessopen++;
862 		returnfd++;
863 #endif
864 	}
865 	if (*lessopen == '-') {
866 		/*
867 		 * Lessopen preprocessor will accept "-" as a filename.
868 		 */
869 		lessopen++;
870 	} else {
871 		if (strcmp(filename, "-") == 0)
872 			return (NULL);
873 	}
874 	if (num_pct_s(lessopen) > 1)
875 	{
876 		error("Invalid LESSOPEN variable", NULL_PARG);
877 		return (NULL);
878 	}
879 
880 	len = (int) (strlen(lessopen) + strlen(filename) + 2);
881 	cmd = (char *) ecalloc(len, sizeof(char));
882 	SNPRINTF1(cmd, len, lessopen, filename);
883 	fd = shellcmd(cmd);
884 	free(cmd);
885 	if (fd == NULL)
886 	{
887 		/*
888 		 * Cannot create the pipe.
889 		 */
890 		return (NULL);
891 	}
892 #if HAVE_FILENO
893 	if (returnfd)
894 	{
895 		int f;
896 		char c;
897 
898 		/*
899 		 * Read one char to see if the pipe will produce any data.
900 		 * If it does, push the char back on the pipe.
901 		 */
902 		f = fileno(fd);
903 		SET_BINARY(f);
904 		if (read(f, &c, 1) != 1)
905 		{
906 			/*
907 			 * Pipe is empty.
908 			 * If more than 1 pipe char was specified,
909 			 * the exit status tells whether the file itself
910 			 * is empty, or if there is no alt file.
911 			 * If only one pipe char, just assume no alt file.
912 			 */
913 			int status = pclose(fd);
914 			if (returnfd > 1 && status == 0) {
915 				*pfd = NULL;
916 				*pf = -1;
917 				return (save(FAKE_EMPTYFILE));
918 			}
919 			return (NULL);
920 		}
921 		ch_ungetchar(c);
922 		*pfd = (void *) fd;
923 		*pf = f;
924 		return (save("-"));
925 	}
926 #endif
927 	cmd = readfd(fd);
928 	pclose(fd);
929 	if (*cmd == '\0')
930 		/*
931 		 * Pipe is empty.  This means there is no alt file.
932 		 */
933 		return (NULL);
934 	return (cmd);
935 #endif /* HAVE_POPEN */
936 }
937 
938 /*
939  * Close a replacement file.
940  */
941 	public void
942 close_altfile(char *altfilename, char *filename, void *pipefd)
943 {
944 #if HAVE_POPEN
945 	char *lessclose;
946 	FILE *fd;
947 	char *cmd;
948 	int len;
949 
950 	if (secure)
951 		return;
952 	if (pipefd != NULL)
953 	{
954 #if OS2
955 		/*
956 		 * The pclose function of OS/2 emx sometimes fails.
957 		 * Send SIGINT to the piped process before closing it.
958 		 */
959 		kill(((FILE*)pipefd)->_pid, SIGINT);
960 #endif
961 		pclose((FILE*) pipefd);
962 	}
963 	if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
964 	     	return;
965 	if (num_pct_s(lessclose) > 2)
966 	{
967 		error("Invalid LESSCLOSE variable", NULL_PARG);
968 		return;
969 	}
970 	len = (int) (strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2);
971 	cmd = (char *) ecalloc(len, sizeof(char));
972 	SNPRINTF2(cmd, len, lessclose, filename, altfilename);
973 	fd = shellcmd(cmd);
974 	free(cmd);
975 	if (fd != NULL)
976 		pclose(fd);
977 #endif
978 }
979 
980 /*
981  * Is the specified file a directory?
982  */
983 	public int
984 is_dir(char *filename)
985 {
986 	int isdir = 0;
987 
988 	filename = shell_unquote(filename);
989 #if HAVE_STAT
990 {
991 	int r;
992 	struct stat statbuf;
993 
994 	r = stat(filename, &statbuf);
995 	isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
996 }
997 #else
998 #ifdef _OSK
999 {
1000 	int f;
1001 
1002 	f = open(filename, S_IREAD | S_IFDIR);
1003 	if (f >= 0)
1004 		close(f);
1005 	isdir = (f >= 0);
1006 }
1007 #endif
1008 #endif
1009 	free(filename);
1010 	return (isdir);
1011 }
1012 
1013 /*
1014  * Returns NULL if the file can be opened and
1015  * is an ordinary file, otherwise an error message
1016  * (if it cannot be opened or is a directory, etc.)
1017  */
1018 	public char *
1019 bad_file(char *filename)
1020 {
1021 	char *m = NULL;
1022 
1023 	filename = shell_unquote(filename);
1024 	if (!force_open && is_dir(filename))
1025 	{
1026 		static char is_a_dir[] = " is a directory";
1027 
1028 		m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
1029 			sizeof(char));
1030 		strcpy(m, filename);
1031 		strcat(m, is_a_dir);
1032 	} else
1033 	{
1034 #if HAVE_STAT
1035 		int r;
1036 		struct stat statbuf;
1037 
1038 		r = stat(filename, &statbuf);
1039 		if (r < 0)
1040 		{
1041 			m = errno_message(filename);
1042 		} else if (force_open)
1043 		{
1044 			m = NULL;
1045 		} else if (!S_ISREG(statbuf.st_mode))
1046 		{
1047 			static char not_reg[] = " is not a regular file (use -f to see it)";
1048 			m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1049 				sizeof(char));
1050 			strcpy(m, filename);
1051 			strcat(m, not_reg);
1052 		}
1053 #endif
1054 	}
1055 	free(filename);
1056 	return (m);
1057 }
1058 
1059 /*
1060  * Return the size of a file, as cheaply as possible.
1061  * In Unix, we can stat the file.
1062  */
1063 	public POSITION
1064 filesize(int f)
1065 {
1066 #if HAVE_STAT
1067 	struct stat statbuf;
1068 
1069 	if (fstat(f, &statbuf) >= 0)
1070 		return ((POSITION) statbuf.st_size);
1071 #else
1072 #ifdef _OSK
1073 	long size;
1074 
1075 	if ((size = (long) _gs_size(f)) >= 0)
1076 		return ((POSITION) size);
1077 #endif
1078 #endif
1079 	return (seek_filesize(f));
1080 }
1081 
1082 /*
1083  *
1084  */
1085 	public char *
1086 shell_coption(void)
1087 {
1088 	return ("-c");
1089 }
1090 
1091 /*
1092  * Return last component of a pathname.
1093  */
1094 	public char *
1095 last_component(char *name)
1096 {
1097 	char *slash;
1098 
1099 	for (slash = name + strlen(name);  slash > name; )
1100 	{
1101 		--slash;
1102 		if (*slash == *PATHNAME_SEP || *slash == '/')
1103 			return (slash + 1);
1104 	}
1105 	return (name);
1106 }
1107 
1108