xref: /freebsd/contrib/less/filename.c (revision d8a0fe102c0cfdfcd5b818f850eff09d8536c9bc)
1 /*
2  * Copyright (C) 1984-2017  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 
36 #if HAVE_STAT
37 #include <sys/stat.h>
38 #ifndef S_ISDIR
39 #define	S_ISDIR(m)	(((m) & S_IFMT) == S_IFDIR)
40 #endif
41 #ifndef S_ISREG
42 #define	S_ISREG(m)	(((m) & S_IFMT) == S_IFREG)
43 #endif
44 #endif
45 
46 extern int force_open;
47 extern int secure;
48 extern int use_lessopen;
49 extern int ctldisp;
50 extern int utf_mode;
51 extern IFILE curr_ifile;
52 extern IFILE old_ifile;
53 #if SPACES_IN_FILENAMES
54 extern char openquote;
55 extern char closequote;
56 #endif
57 
58 /*
59  * Remove quotes around a filename.
60  */
61 	public char *
62 shell_unquote(str)
63 	char *str;
64 {
65 	char *name;
66 	char *p;
67 
68 	name = p = (char *) ecalloc(strlen(str)+1, sizeof(char));
69 	if (*str == openquote)
70 	{
71 		str++;
72 		while (*str != '\0')
73 		{
74 			if (*str == closequote)
75 			{
76 				if (str[1] != closequote)
77 					break;
78 				str++;
79 			}
80 			*p++ = *str++;
81 		}
82 	} else
83 	{
84 		char *esc = get_meta_escape();
85 		int esclen = (int) strlen(esc);
86 		while (*str != '\0')
87 		{
88 			if (esclen > 0 && strncmp(str, esc, esclen) == 0)
89 				str += esclen;
90 			*p++ = *str++;
91 		}
92 	}
93 	*p = '\0';
94 	return (name);
95 }
96 
97 /*
98  * Get the shell's escape character.
99  */
100 	public char *
101 get_meta_escape()
102 {
103 	char *s;
104 
105 	s = lgetenv("LESSMETAESCAPE");
106 	if (s == NULL)
107 		s = DEF_METAESCAPE;
108 	return (s);
109 }
110 
111 /*
112  * Get the characters which the shell considers to be "metacharacters".
113  */
114 	static char *
115 metachars()
116 {
117 	static char *mchars = NULL;
118 
119 	if (mchars == NULL)
120 	{
121 		mchars = lgetenv("LESSMETACHARS");
122 		if (mchars == NULL)
123 			mchars = DEF_METACHARS;
124 	}
125 	return (mchars);
126 }
127 
128 /*
129  * Is this a shell metacharacter?
130  */
131 	static int
132 metachar(c)
133 	char c;
134 {
135 	return (strchr(metachars(), c) != NULL);
136 }
137 
138 /*
139  * Insert a backslash before each metacharacter in a string.
140  */
141 	public char *
142 shell_quote(s)
143 	char *s;
144 {
145 	char *p;
146 	char *newstr;
147 	int len;
148 	char *esc = get_meta_escape();
149 	int esclen = (int) strlen(esc);
150 	int use_quotes = 0;
151 	int have_quotes = 0;
152 
153 	/*
154 	 * Determine how big a string we need to allocate.
155 	 */
156 	len = 1; /* Trailing null byte */
157 	for (p = s;  *p != '\0';  p++)
158 	{
159 		len++;
160 		if (*p == openquote || *p == closequote)
161 			have_quotes = 1;
162 		if (metachar(*p))
163 		{
164 			if (esclen == 0)
165 			{
166 				/*
167 				 * We've got a metachar, but this shell
168 				 * doesn't support escape chars.  Use quotes.
169 				 */
170 				use_quotes = 1;
171 			} else
172 			{
173 				/*
174 				 * Allow space for the escape char.
175 				 */
176 				len += esclen;
177 			}
178 		}
179 	}
180 	if (use_quotes)
181 	{
182 		if (have_quotes)
183 			/*
184 			 * We can't quote a string that contains quotes.
185 			 */
186 			return (NULL);
187 		len = (int) strlen(s) + 3;
188 	}
189 	/*
190 	 * Allocate and construct the new string.
191 	 */
192 	newstr = p = (char *) ecalloc(len, sizeof(char));
193 	if (use_quotes)
194 	{
195 		SNPRINTF3(newstr, len, "%c%s%c", openquote, s, closequote);
196 	} else
197 	{
198 		while (*s != '\0')
199 		{
200 			if (metachar(*s))
201 			{
202 				/*
203 				 * Add the escape char.
204 				 */
205 				strcpy(p, esc);
206 				p += esclen;
207 			}
208 			*p++ = *s++;
209 		}
210 		*p = '\0';
211 	}
212 	return (newstr);
213 }
214 
215 /*
216  * Return a pathname that points to a specified file in a specified directory.
217  * Return NULL if the file does not exist in the directory.
218  */
219 	static char *
220 dirfile(dirname, filename)
221 	char *dirname;
222 	char *filename;
223 {
224 	char *pathname;
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 	f = open(pathname, OPEN_READ);
242 	if (f < 0)
243 	{
244 		free(pathname);
245 		pathname = NULL;
246 	} else
247 	{
248 		close(f);
249 	}
250 	return (pathname);
251 }
252 
253 /*
254  * Return the full pathname of the given file in the "home directory".
255  */
256 	public char *
257 homefile(filename)
258 	char *filename;
259 {
260 	char *pathname;
261 
262 	/*
263 	 * Try $HOME/filename.
264 	 */
265 	pathname = dirfile(lgetenv("HOME"), filename);
266 	if (pathname != NULL)
267 		return (pathname);
268 #if OS2
269 	/*
270 	 * Try $INIT/filename.
271 	 */
272 	pathname = dirfile(lgetenv("INIT"), filename);
273 	if (pathname != NULL)
274 		return (pathname);
275 #endif
276 #if MSDOS_COMPILER || OS2
277 	/*
278 	 * Look for the file anywhere on search path.
279 	 */
280 	pathname = (char *) calloc(_MAX_PATH, sizeof(char));
281 #if MSDOS_COMPILER==DJGPPC
282 	{
283 		char *res = searchpath(filename);
284 		if (res == 0)
285 			*pathname = '\0';
286 		else
287 			strcpy(pathname, res);
288 	}
289 #else
290 	_searchenv(filename, "PATH", pathname);
291 #endif
292 	if (*pathname != '\0')
293 		return (pathname);
294 	free(pathname);
295 #endif
296 	return (NULL);
297 }
298 
299 /*
300  * Expand a string, substituting any "%" with the current filename,
301  * and any "#" with the previous filename.
302  * But a string of N "%"s is just replaced with N-1 "%"s.
303  * Likewise for a string of N "#"s.
304  * {{ This is a lot of work just to support % and #. }}
305  */
306 	public char *
307 fexpand(s)
308 	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(s)
404 	char *s;
405 {
406 	char *fpat;
407 	char *qs;
408 
409 	if (secure)
410 		return (NULL);
411 	/*
412 	 * Complete the filename "s" by globbing "s*".
413 	 */
414 #if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
415 	/*
416 	 * But in DOS, we have to glob "s*.*".
417 	 * But if the final component of the filename already has
418 	 * a dot in it, just do "s*".
419 	 * (Thus, "FILE" is globbed as "FILE*.*",
420 	 *  but "FILE.A" is globbed as "FILE.A*").
421 	 */
422 	{
423 		char *slash;
424 		int len;
425 		for (slash = s+strlen(s)-1;  slash > s;  slash--)
426 			if (*slash == *PATHNAME_SEP || *slash == '/')
427 				break;
428 		len = (int) strlen(s) + 4;
429 		fpat = (char *) ecalloc(len, sizeof(char));
430 		if (strchr(slash, '.') == NULL)
431 			SNPRINTF1(fpat, len, "%s*.*", s);
432 		else
433 			SNPRINTF1(fpat, len, "%s*", s);
434 	}
435 #else
436 	{
437 	int len = (int) strlen(s) + 2;
438 	fpat = (char *) ecalloc(len, sizeof(char));
439 	SNPRINTF1(fpat, len, "%s*", s);
440 	}
441 #endif
442 	qs = lglob(fpat);
443 	s = shell_unquote(qs);
444 	if (strcmp(s,fpat) == 0)
445 	{
446 		/*
447 		 * The filename didn't expand.
448 		 */
449 		free(qs);
450 		qs = NULL;
451 	}
452 	free(s);
453 	free(fpat);
454 	return (qs);
455 }
456 #endif
457 
458 /*
459  * Try to determine if a file is "binary".
460  * This is just a guess, and we need not try too hard to make it accurate.
461  */
462 	public int
463 bin_file(f)
464 	int f;
465 {
466 	int n;
467 	int bin_count = 0;
468 	char data[256];
469 	char* p;
470 	char* edata;
471 
472 	if (!seekable(f))
473 		return (0);
474 	if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
475 		return (0);
476 	n = read(f, data, sizeof(data));
477 	if (n <= 0)
478 		return (0);
479 	edata = &data[n];
480 	for (p = data;  p < edata;  )
481 	{
482 		if (utf_mode && !is_utf8_well_formed(p, edata-data))
483 		{
484 			bin_count++;
485 			utf_skip_to_lead(&p, edata);
486 		} else
487 		{
488 			LWCHAR c = step_char(&p, +1, edata);
489 			if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
490 				skip_ansi(&p, edata);
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(f)
507 	int f;
508 {
509 	off_t spos;
510 
511 	spos = lseek(f, (off_t)0, SEEK_END);
512 	if (spos == BAD_LSEEK)
513 		return (NULL_POSITION);
514 	return ((POSITION) spos);
515 }
516 
517 /*
518  * Read a string from a file.
519  * Return a pointer to the string in memory.
520  */
521 	static char *
522 readfd(fd)
523 	FILE *fd;
524 {
525 	int len;
526 	int ch;
527 	char *buf;
528 	char *p;
529 
530 	/*
531 	 * Make a guess about how many chars in the string
532 	 * and allocate a buffer to hold it.
533 	 */
534 	len = 100;
535 	buf = (char *) ecalloc(len, sizeof(char));
536 	for (p = buf;  ;  p++)
537 	{
538 		if ((ch = getc(fd)) == '\n' || ch == EOF)
539 			break;
540 		if (p - buf >= len-1)
541 		{
542 			/*
543 			 * The string is too big to fit in the buffer we have.
544 			 * Allocate a new buffer, twice as big.
545 			 */
546 			len *= 2;
547 			*p = '\0';
548 			p = (char *) ecalloc(len, sizeof(char));
549 			strcpy(p, buf);
550 			free(buf);
551 			buf = p;
552 			p = buf + strlen(buf);
553 		}
554 		*p = ch;
555 	}
556 	*p = '\0';
557 	return (buf);
558 }
559 
560 
561 
562 #if HAVE_POPEN
563 
564 FILE *popen();
565 
566 /*
567  * Execute a shell command.
568  * Return a pointer to a pipe connected to the shell command's standard output.
569  */
570 	static FILE *
571 shellcmd(cmd)
572 	char *cmd;
573 {
574 	FILE *fd;
575 
576 #if HAVE_SHELL
577 	char *shell;
578 
579 	shell = lgetenv("SHELL");
580 	if (shell != NULL && *shell != '\0')
581 	{
582 		char *scmd;
583 		char *esccmd;
584 
585 		/*
586 		 * Read the output of <$SHELL -c cmd>.
587 		 * Escape any metacharacters in the command.
588 		 */
589 		esccmd = shell_quote(cmd);
590 		if (esccmd == NULL)
591 		{
592 			fd = popen(cmd, "r");
593 		} else
594 		{
595 			int len = (int) (strlen(shell) + strlen(esccmd) + 5);
596 			scmd = (char *) ecalloc(len, sizeof(char));
597 			SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
598 			free(esccmd);
599 			fd = popen(scmd, "r");
600 			free(scmd);
601 		}
602 	} else
603 #endif
604 	{
605 		fd = popen(cmd, "r");
606 	}
607 	/*
608 	 * Redirection in `popen' might have messed with the
609 	 * standard devices.  Restore binary input mode.
610 	 */
611 	SET_BINARY(0);
612 	return (fd);
613 }
614 
615 #endif /* HAVE_POPEN */
616 
617 
618 /*
619  * Expand a filename, doing any system-specific metacharacter substitutions.
620  */
621 	public char *
622 lglob(filename)
623 	char *filename;
624 {
625 	char *gfilename;
626 
627 	filename = fexpand(filename);
628 	if (secure)
629 		return (filename);
630 
631 #ifdef DECL_GLOB_LIST
632 {
633 	/*
634 	 * The globbing function returns a list of names.
635 	 */
636 	int length;
637 	char *p;
638 	char *qfilename;
639 	DECL_GLOB_LIST(list)
640 
641 	GLOB_LIST(filename, list);
642 	if (GLOB_LIST_FAILED(list))
643 	{
644 		return (filename);
645 	}
646 	length = 1; /* Room for trailing null byte */
647 	for (SCAN_GLOB_LIST(list, p))
648 	{
649 		INIT_GLOB_LIST(list, p);
650 		qfilename = shell_quote(p);
651 		if (qfilename != NULL)
652 		{
653 	  		length += strlen(qfilename) + 1;
654 			free(qfilename);
655 		}
656 	}
657 	gfilename = (char *) ecalloc(length, sizeof(char));
658 	for (SCAN_GLOB_LIST(list, p))
659 	{
660 		INIT_GLOB_LIST(list, p);
661 		qfilename = shell_quote(p);
662 		if (qfilename != NULL)
663 		{
664 			sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
665 			free(qfilename);
666 		}
667 	}
668 	/*
669 	 * Overwrite the final trailing space with a null terminator.
670 	 */
671 	*--p = '\0';
672 	GLOB_LIST_DONE(list);
673 }
674 #else
675 #ifdef DECL_GLOB_NAME
676 {
677 	/*
678 	 * The globbing function returns a single name, and
679 	 * is called multiple times to walk thru all names.
680 	 */
681 	char *p;
682 	int len;
683 	int n;
684 	char *pfilename;
685 	char *qfilename;
686 	DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
687 
688 	GLOB_FIRST_NAME(filename, &fnd, handle);
689 	if (GLOB_FIRST_FAILED(handle))
690 	{
691 		return (filename);
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 		pfilename = (char *) ecalloc(n, sizeof(char));
701 		SNPRINTF3(pfilename, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
702 		qfilename = shell_quote(pfilename);
703 		free(pfilename);
704 		if (qfilename != NULL)
705 		{
706 			n = (int) strlen(qfilename);
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, qfilename);
722 			free(qfilename);
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 		return (filename);
755 	}
756 	lessecho = lgetenv("LESSECHO");
757 	if (lessecho == NULL || *lessecho == '\0')
758 		lessecho = "lessecho";
759 	/*
760 	 * Invoke lessecho, and read its output (a globbed list of filenames).
761 	 */
762 	len = (int) (strlen(lessecho) + strlen(filename) + (7*strlen(metachars())) + 24);
763 	cmd = (char *) ecalloc(len, sizeof(char));
764 	SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
765 	free(esc);
766 	for (s = metachars();  *s != '\0';  s++)
767 		sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
768 	sprintf(cmd + strlen(cmd), "-- %s", filename);
769 	fd = shellcmd(cmd);
770 	free(cmd);
771 	if (fd == NULL)
772 	{
773 		/*
774 		 * Cannot create the pipe.
775 		 * Just return the original (fexpanded) filename.
776 		 */
777 		return (filename);
778 	}
779 	gfilename = readfd(fd);
780 	pclose(fd);
781 	if (*gfilename == '\0')
782 	{
783 		free(gfilename);
784 		return (save(filename));
785 	}
786 }
787 #else
788 	/*
789 	 * No globbing functions at all.  Just use the fexpanded filename.
790 	 */
791 	gfilename = save(filename);
792 #endif
793 #endif
794 #endif
795 	free(filename);
796 	return (gfilename);
797 }
798 
799 /*
800  * Return number of %s escapes in a string.
801  * Return a large number if there are any other % escapes besides %s.
802  */
803 	static int
804 num_pct_s(lessopen)
805 	char *lessopen;
806 {
807 	int num = 0;
808 
809 	while (*lessopen != '\0')
810 	{
811 		if (*lessopen == '%')
812 		{
813 			if (lessopen[1] == '%')
814 				++lessopen;
815 			else if (lessopen[1] == 's')
816 				++num;
817 			else
818 				return (999);
819 		}
820 		++lessopen;
821 	}
822 	return (num);
823 }
824 
825 /*
826  * See if we should open a "replacement file"
827  * instead of the file we're about to open.
828  */
829 	public char *
830 open_altfile(filename, pf, pfd)
831 	char *filename;
832 	int *pf;
833 	void **pfd;
834 {
835 #if !HAVE_POPEN
836 	return (NULL);
837 #else
838 	char *lessopen;
839 	char *qfilename;
840 	char *cmd;
841 	int len;
842 	FILE *fd;
843 #if HAVE_FILENO
844 	int returnfd = 0;
845 #endif
846 
847 	if (!use_lessopen || secure)
848 		return (NULL);
849 	ch_ungetchar(-1);
850 	if ((lessopen = lgetenv("LESSOPEN")) == NULL)
851 		return (NULL);
852 	while (*lessopen == '|')
853 	{
854 		/*
855 		 * If LESSOPEN starts with a |, it indicates
856 		 * a "pipe preprocessor".
857 		 */
858 #if !HAVE_FILENO
859 		error("LESSOPEN pipe is not supported", NULL_PARG);
860 		return (NULL);
861 #else
862 		lessopen++;
863 		returnfd++;
864 #endif
865 	}
866 	if (*lessopen == '-')
867 	{
868 		/*
869 		 * Lessopen preprocessor will accept "-" as a filename.
870 		 */
871 		lessopen++;
872 	} else
873 	{
874 		if (strcmp(filename, "-") == 0)
875 			return (NULL);
876 	}
877 	if (num_pct_s(lessopen) != 1)
878 	{
879 		error("LESSOPEN ignored: must contain exactly one %%s", NULL_PARG);
880 		return (NULL);
881 	}
882 
883 	qfilename = shell_quote(filename);
884 	len = (int) (strlen(lessopen) + strlen(qfilename) + 2);
885 	cmd = (char *) ecalloc(len, sizeof(char));
886 	SNPRINTF1(cmd, len, lessopen, qfilename);
887 	free(qfilename);
888 	fd = shellcmd(cmd);
889 	free(cmd);
890 	if (fd == NULL)
891 	{
892 		/*
893 		 * Cannot create the pipe.
894 		 */
895 		return (NULL);
896 	}
897 #if HAVE_FILENO
898 	if (returnfd)
899 	{
900 		char c;
901 		int f;
902 
903 		/*
904 		 * The first time we open the file, read one char
905 		 * to see if the pipe will produce any data.
906 		 * If it does, push the char back on the pipe.
907 		 */
908 		f = fileno(fd);
909 		SET_BINARY(f);
910 		if (read(f, &c, 1) != 1)
911 		{
912 			/*
913 			 * Pipe is empty.
914 			 * If more than 1 pipe char was specified,
915 			 * the exit status tells whether the file itself
916 			 * is empty, or if there is no alt file.
917 			 * If only one pipe char, just assume no alt file.
918 			 */
919 			int status = pclose(fd);
920 			if (returnfd > 1 && status == 0) {
921 				*pfd = NULL;
922 				*pf = -1;
923 				return (save(FAKE_EMPTYFILE));
924 			}
925 			return (NULL);
926 		}
927 		ch_ungetchar(c);
928 		*pfd = (void *) fd;
929 		*pf = f;
930 		return (save("-"));
931 	}
932 #endif
933 	cmd = readfd(fd);
934 	pclose(fd);
935 	if (*cmd == '\0')
936 		/*
937 		 * Pipe is empty.  This means there is no alt file.
938 		 */
939 		return (NULL);
940 	return (cmd);
941 #endif /* HAVE_POPEN */
942 }
943 
944 /*
945  * Close a replacement file.
946  */
947 	public void
948 close_altfile(altfilename, filename)
949 	char *altfilename;
950 	char *filename;
951 {
952 #if HAVE_POPEN
953 	char *lessclose;
954 	FILE *fd;
955 	char *cmd;
956 	int len;
957 
958 	if (secure)
959 		return;
960 	ch_ungetchar(-1);
961 	if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
962 	     	return;
963 	if (num_pct_s(lessclose) > 2)
964 	{
965 		error("LESSCLOSE ignored; must contain no more than 2 %%s", NULL_PARG);
966 		return;
967 	}
968 	len = (int) (strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2);
969 	cmd = (char *) ecalloc(len, sizeof(char));
970 	SNPRINTF2(cmd, len, lessclose, filename, altfilename);
971 	fd = shellcmd(cmd);
972 	free(cmd);
973 	if (fd != NULL)
974 		pclose(fd);
975 #endif
976 }
977 
978 /*
979  * Is the specified file a directory?
980  */
981 	public int
982 is_dir(filename)
983 	char *filename;
984 {
985 	int isdir = 0;
986 
987 #if HAVE_STAT
988 {
989 	int r;
990 	struct stat statbuf;
991 
992 	r = stat(filename, &statbuf);
993 	isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
994 }
995 #else
996 #ifdef _OSK
997 {
998 	int f;
999 
1000 	f = open(filename, S_IREAD | S_IFDIR);
1001 	if (f >= 0)
1002 		close(f);
1003 	isdir = (f >= 0);
1004 }
1005 #endif
1006 #endif
1007 	return (isdir);
1008 }
1009 
1010 /*
1011  * Returns NULL if the file can be opened and
1012  * is an ordinary file, otherwise an error message
1013  * (if it cannot be opened or is a directory, etc.)
1014  */
1015 	public char *
1016 bad_file(filename)
1017 	char *filename;
1018 {
1019 	char *m = NULL;
1020 
1021 	if (!force_open && is_dir(filename))
1022 	{
1023 		static char is_a_dir[] = " is a directory";
1024 
1025 		m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
1026 			sizeof(char));
1027 		strcpy(m, filename);
1028 		strcat(m, is_a_dir);
1029 	} else
1030 	{
1031 #if HAVE_STAT
1032 		int r;
1033 		struct stat statbuf;
1034 
1035 		r = stat(filename, &statbuf);
1036 		if (r < 0)
1037 		{
1038 			m = errno_message(filename);
1039 		} else if (force_open)
1040 		{
1041 			m = NULL;
1042 		} else if (!S_ISREG(statbuf.st_mode))
1043 		{
1044 			static char not_reg[] = " is not a regular file (use -f to see it)";
1045 			m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1046 				sizeof(char));
1047 			strcpy(m, filename);
1048 			strcat(m, not_reg);
1049 		}
1050 #endif
1051 	}
1052 	return (m);
1053 }
1054 
1055 /*
1056  * Return the size of a file, as cheaply as possible.
1057  * In Unix, we can stat the file.
1058  */
1059 	public POSITION
1060 filesize(f)
1061 	int f;
1062 {
1063 #if HAVE_STAT
1064 	struct stat statbuf;
1065 
1066 	if (fstat(f, &statbuf) >= 0)
1067 		return ((POSITION) statbuf.st_size);
1068 #else
1069 #ifdef _OSK
1070 	long size;
1071 
1072 	if ((size = (long) _gs_size(f)) >= 0)
1073 		return ((POSITION) size);
1074 #endif
1075 #endif
1076 	return (seek_filesize(f));
1077 }
1078 
1079 /*
1080  *
1081  */
1082 	public char *
1083 shell_coption()
1084 {
1085 	return ("-c");
1086 }
1087 
1088 /*
1089  * Return last component of a pathname.
1090  */
1091 	public char *
1092 last_component(name)
1093 	char *name;
1094 {
1095 	char *slash;
1096 
1097 	for (slash = name + strlen(name);  slash > name; )
1098 	{
1099 		--slash;
1100 		if (*slash == *PATHNAME_SEP || *slash == '/')
1101 			return (slash + 1);
1102 	}
1103 	return (name);
1104 }
1105 
1106