xref: /freebsd/contrib/less/filename.c (revision c6989859ae9388eeb46a24fe88f9b8d07101c710)
1 /*
2  * Copyright (C) 1984-2019  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(VOID_PARAM)
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(VOID_PARAM)
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 /*
565  * Execute a shell command.
566  * Return a pointer to a pipe connected to the shell command's standard output.
567  */
568 	static FILE *
569 shellcmd(cmd)
570 	char *cmd;
571 {
572 	FILE *fd;
573 
574 #if HAVE_SHELL
575 	char *shell;
576 
577 	shell = lgetenv("SHELL");
578 	if (!isnullenv(shell))
579 	{
580 		char *scmd;
581 		char *esccmd;
582 
583 		/*
584 		 * Read the output of <$SHELL -c cmd>.
585 		 * Escape any metacharacters in the command.
586 		 */
587 		esccmd = shell_quote(cmd);
588 		if (esccmd == NULL)
589 		{
590 			fd = popen(cmd, "r");
591 		} else
592 		{
593 			int len = (int) (strlen(shell) + strlen(esccmd) + 5);
594 			scmd = (char *) ecalloc(len, sizeof(char));
595 			SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
596 			free(esccmd);
597 			fd = popen(scmd, "r");
598 			free(scmd);
599 		}
600 	} else
601 #endif
602 	{
603 		fd = popen(cmd, "r");
604 	}
605 	/*
606 	 * Redirection in `popen' might have messed with the
607 	 * standard devices.  Restore binary input mode.
608 	 */
609 	SET_BINARY(0);
610 	return (fd);
611 }
612 
613 #endif /* HAVE_POPEN */
614 
615 
616 /*
617  * Expand a filename, doing any system-specific metacharacter substitutions.
618  */
619 	public char *
620 lglob(filename)
621 	char *filename;
622 {
623 	char *gfilename;
624 
625 	filename = fexpand(filename);
626 	if (secure)
627 		return (filename);
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 		return (filename);
643 	}
644 	length = 1; /* Room for trailing null byte */
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 	  		length += strlen(qfilename) + 1;
652 			free(qfilename);
653 		}
654 	}
655 	gfilename = (char *) ecalloc(length, sizeof(char));
656 	for (SCAN_GLOB_LIST(list, p))
657 	{
658 		INIT_GLOB_LIST(list, p);
659 		qfilename = shell_quote(p);
660 		if (qfilename != NULL)
661 		{
662 			sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
663 			free(qfilename);
664 		}
665 	}
666 	/*
667 	 * Overwrite the final trailing space with a null terminator.
668 	 */
669 	*--p = '\0';
670 	GLOB_LIST_DONE(list);
671 }
672 #else
673 #ifdef DECL_GLOB_NAME
674 {
675 	/*
676 	 * The globbing function returns a single name, and
677 	 * is called multiple times to walk thru all names.
678 	 */
679 	char *p;
680 	int len;
681 	int n;
682 	char *pfilename;
683 	char *qfilename;
684 	DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
685 
686 	GLOB_FIRST_NAME(filename, &fnd, handle);
687 	if (GLOB_FIRST_FAILED(handle))
688 	{
689 		return (filename);
690 	}
691 
692 	_splitpath(filename, drive, dir, fname, ext);
693 	len = 100;
694 	gfilename = (char *) ecalloc(len, sizeof(char));
695 	p = gfilename;
696 	do {
697 		n = (int) (strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1);
698 		pfilename = (char *) ecalloc(n, sizeof(char));
699 		SNPRINTF3(pfilename, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
700 		qfilename = shell_quote(pfilename);
701 		free(pfilename);
702 		if (qfilename != NULL)
703 		{
704 			n = (int) strlen(qfilename);
705 			while (p - gfilename + n + 2 >= len)
706 			{
707 				/*
708 				 * No room in current buffer.
709 				 * Allocate a bigger one.
710 				 */
711 				len *= 2;
712 				*p = '\0';
713 				p = (char *) ecalloc(len, sizeof(char));
714 				strcpy(p, gfilename);
715 				free(gfilename);
716 				gfilename = p;
717 				p = gfilename + strlen(gfilename);
718 			}
719 			strcpy(p, qfilename);
720 			free(qfilename);
721 			p += n;
722 			*p++ = ' ';
723 		}
724 	} while (GLOB_NEXT_NAME(handle, &fnd) == 0);
725 
726 	/*
727 	 * Overwrite the final trailing space with a null terminator.
728 	 */
729 	*--p = '\0';
730 	GLOB_NAME_DONE(handle);
731 }
732 #else
733 #if HAVE_POPEN
734 {
735 	/*
736 	 * We get the shell to glob the filename for us by passing
737 	 * an "echo" command to the shell and reading its output.
738 	 */
739 	FILE *fd;
740 	char *s;
741 	char *lessecho;
742 	char *cmd;
743 	char *esc;
744 	int len;
745 
746 	esc = get_meta_escape();
747 	if (strlen(esc) == 0)
748 		esc = "-";
749 	esc = shell_quote(esc);
750 	if (esc == NULL)
751 	{
752 		return (filename);
753 	}
754 	lessecho = lgetenv("LESSECHO");
755 	if (isnullenv(lessecho))
756 		lessecho = "lessecho";
757 	/*
758 	 * Invoke lessecho, and read its output (a globbed list of filenames).
759 	 */
760 	len = (int) (strlen(lessecho) + strlen(filename) + (7*strlen(metachars())) + 24);
761 	cmd = (char *) ecalloc(len, sizeof(char));
762 	SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
763 	free(esc);
764 	for (s = metachars();  *s != '\0';  s++)
765 		sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
766 	sprintf(cmd + strlen(cmd), "-- %s", filename);
767 	fd = shellcmd(cmd);
768 	free(cmd);
769 	if (fd == NULL)
770 	{
771 		/*
772 		 * Cannot create the pipe.
773 		 * Just return the original (fexpanded) filename.
774 		 */
775 		return (filename);
776 	}
777 	gfilename = readfd(fd);
778 	pclose(fd);
779 	if (*gfilename == '\0')
780 	{
781 		free(gfilename);
782 		return (filename);
783 	}
784 }
785 #else
786 	/*
787 	 * No globbing functions at all.  Just use the fexpanded filename.
788 	 */
789 	gfilename = save(filename);
790 #endif
791 #endif
792 #endif
793 	free(filename);
794 	return (gfilename);
795 }
796 
797 /*
798  * @@@
799  */
800 	public char *
801 lrealpath(path)
802 	char *path;
803 {
804 #if HAVE_REALPATH
805 	char rpath[PATH_MAX];
806 	if (realpath(path, rpath) != NULL)
807 		return (save(rpath));
808 #endif
809 	return (save(path));
810 }
811 
812 /*
813  * Return number of %s escapes in a string.
814  * Return a large number if there are any other % escapes besides %s.
815  */
816 	static int
817 num_pct_s(lessopen)
818 	char *lessopen;
819 {
820 	int num = 0;
821 
822 	while (*lessopen != '\0')
823 	{
824 		if (*lessopen == '%')
825 		{
826 			if (lessopen[1] == '%')
827 				++lessopen;
828 			else if (lessopen[1] == 's')
829 				++num;
830 			else
831 				return (999);
832 		}
833 		++lessopen;
834 	}
835 	return (num);
836 }
837 
838 /*
839  * See if we should open a "replacement file"
840  * instead of the file we're about to open.
841  */
842 	public char *
843 open_altfile(filename, pf, pfd)
844 	char *filename;
845 	int *pf;
846 	void **pfd;
847 {
848 #if !HAVE_POPEN
849 	return (NULL);
850 #else
851 	char *lessopen;
852 	char *qfilename;
853 	char *cmd;
854 	int len;
855 	FILE *fd;
856 #if HAVE_FILENO
857 	int returnfd = 0;
858 #endif
859 
860 	if (!use_lessopen || secure)
861 		return (NULL);
862 	ch_ungetchar(-1);
863 	if ((lessopen = lgetenv("LESSOPEN")) == NULL)
864 		return (NULL);
865 	while (*lessopen == '|')
866 	{
867 		/*
868 		 * If LESSOPEN starts with a |, it indicates
869 		 * a "pipe preprocessor".
870 		 */
871 #if !HAVE_FILENO
872 		error("LESSOPEN pipe is not supported", NULL_PARG);
873 		return (NULL);
874 #else
875 		lessopen++;
876 		returnfd++;
877 #endif
878 	}
879 	if (*lessopen == '-')
880 	{
881 		/*
882 		 * Lessopen preprocessor will accept "-" as a filename.
883 		 */
884 		lessopen++;
885 	} else
886 	{
887 		if (strcmp(filename, "-") == 0)
888 			return (NULL);
889 	}
890 	if (num_pct_s(lessopen) != 1)
891 	{
892 		error("LESSOPEN ignored: must contain exactly one %%s", NULL_PARG);
893 		return (NULL);
894 	}
895 
896 	qfilename = shell_quote(filename);
897 	len = (int) (strlen(lessopen) + strlen(qfilename) + 2);
898 	cmd = (char *) ecalloc(len, sizeof(char));
899 	SNPRINTF1(cmd, len, lessopen, qfilename);
900 	free(qfilename);
901 	fd = shellcmd(cmd);
902 	free(cmd);
903 	if (fd == NULL)
904 	{
905 		/*
906 		 * Cannot create the pipe.
907 		 */
908 		return (NULL);
909 	}
910 #if HAVE_FILENO
911 	if (returnfd)
912 	{
913 		char c;
914 		int f;
915 
916 		/*
917 		 * The first time we open the file, read one char
918 		 * to see if the pipe will produce any data.
919 		 * If it does, push the char back on the pipe.
920 		 */
921 		f = fileno(fd);
922 		SET_BINARY(f);
923 		if (read(f, &c, 1) != 1)
924 		{
925 			/*
926 			 * Pipe is empty.
927 			 * If more than 1 pipe char was specified,
928 			 * the exit status tells whether the file itself
929 			 * is empty, or if there is no alt file.
930 			 * If only one pipe char, just assume no alt file.
931 			 */
932 			int status = pclose(fd);
933 			if (returnfd > 1 && status == 0) {
934 				*pfd = NULL;
935 				*pf = -1;
936 				return (save(FAKE_EMPTYFILE));
937 			}
938 			return (NULL);
939 		}
940 		ch_ungetchar(c);
941 		*pfd = (void *) fd;
942 		*pf = f;
943 		return (save("-"));
944 	}
945 #endif
946 	cmd = readfd(fd);
947 	pclose(fd);
948 	if (*cmd == '\0')
949 		/*
950 		 * Pipe is empty.  This means there is no alt file.
951 		 */
952 		return (NULL);
953 	return (cmd);
954 #endif /* HAVE_POPEN */
955 }
956 
957 /*
958  * Close a replacement file.
959  */
960 	public void
961 close_altfile(altfilename, filename)
962 	char *altfilename;
963 	char *filename;
964 {
965 #if HAVE_POPEN
966 	char *lessclose;
967 	FILE *fd;
968 	char *cmd;
969 	int len;
970 
971 	if (secure)
972 		return;
973 	ch_ungetchar(-1);
974 	if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
975 	     	return;
976 	if (num_pct_s(lessclose) > 2)
977 	{
978 		error("LESSCLOSE ignored; must contain no more than 2 %%s", NULL_PARG);
979 		return;
980 	}
981 	len = (int) (strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2);
982 	cmd = (char *) ecalloc(len, sizeof(char));
983 	SNPRINTF2(cmd, len, lessclose, filename, altfilename);
984 	fd = shellcmd(cmd);
985 	free(cmd);
986 	if (fd != NULL)
987 		pclose(fd);
988 #endif
989 }
990 
991 /*
992  * Is the specified file a directory?
993  */
994 	public int
995 is_dir(filename)
996 	char *filename;
997 {
998 	int isdir = 0;
999 
1000 #if HAVE_STAT
1001 {
1002 	int r;
1003 	struct stat statbuf;
1004 
1005 	r = stat(filename, &statbuf);
1006 	isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
1007 }
1008 #else
1009 #ifdef _OSK
1010 {
1011 	int f;
1012 
1013 	f = open(filename, S_IREAD | S_IFDIR);
1014 	if (f >= 0)
1015 		close(f);
1016 	isdir = (f >= 0);
1017 }
1018 #endif
1019 #endif
1020 	return (isdir);
1021 }
1022 
1023 /*
1024  * Returns NULL if the file can be opened and
1025  * is an ordinary file, otherwise an error message
1026  * (if it cannot be opened or is a directory, etc.)
1027  */
1028 	public char *
1029 bad_file(filename)
1030 	char *filename;
1031 {
1032 	char *m = NULL;
1033 
1034 	if (!force_open && is_dir(filename))
1035 	{
1036 		static char is_a_dir[] = " is a directory";
1037 
1038 		m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
1039 			sizeof(char));
1040 		strcpy(m, filename);
1041 		strcat(m, is_a_dir);
1042 	} else
1043 	{
1044 #if HAVE_STAT
1045 		int r;
1046 		struct stat statbuf;
1047 
1048 		r = stat(filename, &statbuf);
1049 		if (r < 0)
1050 		{
1051 			m = errno_message(filename);
1052 		} else if (force_open)
1053 		{
1054 			m = NULL;
1055 		} else if (!S_ISREG(statbuf.st_mode))
1056 		{
1057 			static char not_reg[] = " is not a regular file (use -f to see it)";
1058 			m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1059 				sizeof(char));
1060 			strcpy(m, filename);
1061 			strcat(m, not_reg);
1062 		}
1063 #endif
1064 	}
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(VOID_PARAM)
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 
1119