xref: /minix/external/bsd/less/dist/filename.c (revision 84d9c625)
1 /*	$NetBSD: filename.c,v 1.4 2013/09/04 19:44:21 tron Exp $	*/
2 
3 /*
4  * Copyright (C) 1984-2012  Mark Nudelman
5  *
6  * You may distribute under the terms of either the GNU General Public
7  * License or the Less License, as specified in the README file.
8  *
9  * For more information, see the README file.
10  */
11 
12 
13 /*
14  * Routines to mess around with filenames (and files).
15  * Much of this is very OS dependent.
16  */
17 
18 #include "less.h"
19 #include "lglob.h"
20 #if MSDOS_COMPILER
21 #include <dos.h>
22 #if MSDOS_COMPILER==WIN32C && !defined(_MSC_VER)
23 #include <dir.h>
24 #endif
25 #if MSDOS_COMPILER==DJGPPC
26 #include <glob.h>
27 #include <dir.h>
28 #define _MAX_PATH	PATH_MAX
29 #endif
30 #endif
31 #ifdef _OSK
32 #include <rbf.h>
33 #ifndef _OSK_MWC32
34 #include <modes.h>
35 #endif
36 #endif
37 #if OS2
38 #include <signal.h>
39 #endif
40 
41 #if HAVE_STAT
42 #include <sys/stat.h>
43 #ifndef S_ISDIR
44 #define	S_ISDIR(m)	(((m) & S_IFMT) == S_IFDIR)
45 #endif
46 #ifndef S_ISREG
47 #define	S_ISREG(m)	(((m) & S_IFMT) == S_IFREG)
48 #endif
49 #endif
50 
51 
52 extern int force_open;
53 extern int secure;
54 extern int use_lessopen;
55 extern int ctldisp;
56 extern int utf_mode;
57 extern IFILE curr_ifile;
58 extern IFILE old_ifile;
59 #if SPACES_IN_FILENAMES
60 extern char openquote;
61 extern char closequote;
62 #endif
63 
64 static char *dirfile __P((char *, char *));
65 static POSITION seek_filesize __P((int));
66 static char *readfd __P((FILE *));
67 static int metachar __P((int));
68 static FILE *shellcmd __P((char *));
69 
70 /*
71  * Remove quotes around a filename.
72  */
73 	public char *
shell_unquote(str)74 shell_unquote(str)
75 	char *str;
76 {
77 	char *name;
78 	char *p;
79 
80 	name = p = (char *) ecalloc(strlen(str)+1, sizeof(char));
81 	if (*str == openquote)
82 	{
83 		str++;
84 		while (*str != '\0')
85 		{
86 			if (*str == closequote)
87 			{
88 				if (str[1] != closequote)
89 					break;
90 				str++;
91 			}
92 			*p++ = *str++;
93 		}
94 	} else
95 	{
96 		char *esc = get_meta_escape();
97 		int esclen = strlen(esc);
98 		while (*str != '\0')
99 		{
100 			if (esclen > 0 && strncmp(str, esc, esclen) == 0)
101 				str += esclen;
102 			*p++ = *str++;
103 		}
104 	}
105 	*p = '\0';
106 	return (name);
107 }
108 
109 /*
110  * Get the shell's escape character.
111  */
112 	public char *
get_meta_escape()113 get_meta_escape()
114 {
115 	char *s;
116 
117 	s = lgetenv("LESSMETAESCAPE");
118 	if (s == NULL)
119 		s = DEF_METAESCAPE;
120 	return (s);
121 }
122 
123 /*
124  * Get the characters which the shell considers to be "metacharacters".
125  */
126 	static char *
metachars()127 metachars()
128 {
129 	static char *mchars = NULL;
130 
131 	if (mchars == NULL)
132 	{
133 		mchars = lgetenv("LESSMETACHARS");
134 		if (mchars == NULL)
135 			mchars = DEF_METACHARS;
136 	}
137 	return (mchars);
138 }
139 
140 /*
141  * Is this a shell metacharacter?
142  */
143 	static int
metachar(c)144 metachar(c)
145 	char c;
146 {
147 	return (strchr(metachars(), c) != NULL);
148 }
149 
150 /*
151  * Insert a backslash before each metacharacter in a string.
152  */
153 	public char *
shell_quote(s)154 shell_quote(s)
155 	char *s;
156 {
157 	char *p;
158 	char *newstr;
159 	int len;
160 	char *esc = get_meta_escape();
161 	int esclen = strlen(esc);
162 	int use_quotes = 0;
163 	int have_quotes = 0;
164 
165 	/*
166 	 * Determine how big a string we need to allocate.
167 	 */
168 	len = 1; /* Trailing null byte */
169 	for (p = s;  *p != '\0';  p++)
170 	{
171 		len++;
172 		if (*p == openquote || *p == closequote)
173 			have_quotes = 1;
174 		if (metachar(*p))
175 		{
176 			if (esclen == 0)
177 			{
178 				/*
179 				 * We've got a metachar, but this shell
180 				 * doesn't support escape chars.  Use quotes.
181 				 */
182 				use_quotes = 1;
183 			} else
184 			{
185 				/*
186 				 * Allow space for the escape char.
187 				 */
188 				len += esclen;
189 			}
190 		}
191 	}
192 	if (use_quotes)
193 	{
194 		if (have_quotes)
195 			/*
196 			 * We can't quote a string that contains quotes.
197 			 */
198 			return (NULL);
199 		len = strlen(s) + 3;
200 	}
201 	/*
202 	 * Allocate and construct the new string.
203 	 */
204 	newstr = p = (char *) ecalloc(len, sizeof(char));
205 	if (use_quotes)
206 	{
207 		SNPRINTF3(newstr, len, "%c%s%c", openquote, s, closequote);
208 	} else
209 	{
210 		while (*s != '\0')
211 		{
212 			if (metachar(*s))
213 			{
214 				/*
215 				 * Add the escape char.
216 				 */
217 				strcpy(p, esc);
218 				p += esclen;
219 			}
220 			*p++ = *s++;
221 		}
222 		*p = '\0';
223 	}
224 	return (newstr);
225 }
226 
227 /*
228  * Return a pathname that points to a specified file in a specified directory.
229  * Return NULL if the file does not exist in the directory.
230  */
231 	static char *
dirfile(dirname,filename)232 dirfile(dirname, filename)
233 	char *dirname;
234 	char *filename;
235 {
236 	char *pathname;
237 	char *qpathname;
238 	int len;
239 	int f;
240 
241 	if (dirname == NULL || *dirname == '\0')
242 		return (NULL);
243 	/*
244 	 * Construct the full pathname.
245 	 */
246 	len= strlen(dirname) + strlen(filename) + 2;
247 	pathname = (char *) calloc(len, sizeof(char));
248 	if (pathname == NULL)
249 		return (NULL);
250 	SNPRINTF3(pathname, len, "%s%s%s", dirname, PATHNAME_SEP, filename);
251 	/*
252 	 * Make sure the file exists.
253 	 */
254 	qpathname = shell_unquote(pathname);
255 	f = open(qpathname, OPEN_READ);
256 	if (f < 0)
257 	{
258 		free(pathname);
259 		pathname = NULL;
260 	} else
261 	{
262 		close(f);
263 	}
264 	free(qpathname);
265 	return (pathname);
266 }
267 
268 /*
269  * Return the full pathname of the given file in the "home directory".
270  */
271 	public char *
homefile(filename)272 homefile(filename)
273 	char *filename;
274 {
275 	register char *pathname;
276 
277 	/*
278 	 * Try $HOME/filename.
279 	 */
280 	pathname = dirfile(lgetenv("HOME"), filename);
281 	if (pathname != NULL)
282 		return (pathname);
283 #if OS2
284 	/*
285 	 * Try $INIT/filename.
286 	 */
287 	pathname = dirfile(lgetenv("INIT"), filename);
288 	if (pathname != NULL)
289 		return (pathname);
290 #endif
291 #if MSDOS_COMPILER || OS2
292 	/*
293 	 * Look for the file anywhere on search path.
294 	 */
295 	pathname = (char *) calloc(_MAX_PATH, sizeof(char));
296 #if MSDOS_COMPILER==DJGPPC
297 	{
298 		char *res = searchpath(filename);
299 		if (res == 0)
300 			*pathname = '\0';
301 		else
302 			strcpy(pathname, res);
303 	}
304 #else
305 	_searchenv(filename, "PATH", pathname);
306 #endif
307 	if (*pathname != '\0')
308 		return (pathname);
309 	free(pathname);
310 #endif
311 	return (NULL);
312 }
313 
314 /*
315  * Expand a string, substituting any "%" with the current filename,
316  * and any "#" with the previous filename.
317  * But a string of N "%"s is just replaced with N-1 "%"s.
318  * Likewise for a string of N "#"s.
319  * {{ This is a lot of work just to support % and #. }}
320  */
321 	public char *
fexpand(s)322 fexpand(s)
323 	char *s;
324 {
325 	register char *fr, *to;
326 	register int n;
327 	register char *e;
328 	IFILE ifile;
329 
330 #define	fchar_ifile(c) \
331 	((c) == '%' ? curr_ifile : \
332 	 (c) == '#' ? old_ifile : NULL_IFILE)
333 
334 	/*
335 	 * Make one pass to see how big a buffer we
336 	 * need to allocate for the expanded string.
337 	 */
338 	n = 0;
339 	for (fr = s;  *fr != '\0';  fr++)
340 	{
341 		switch (*fr)
342 		{
343 		case '%':
344 		case '#':
345 			if (fr > s && fr[-1] == *fr)
346 			{
347 				/*
348 				 * Second (or later) char in a string
349 				 * of identical chars.  Treat as normal.
350 				 */
351 				n++;
352 			} else if (fr[1] != *fr)
353 			{
354 				/*
355 				 * Single char (not repeated).  Treat specially.
356 				 */
357 				ifile = fchar_ifile(*fr);
358 				if (ifile == NULL_IFILE)
359 					n++;
360 				else
361 					n += strlen(get_filename(ifile));
362 			}
363 			/*
364 			 * Else it is the first char in a string of
365 			 * identical chars.  Just discard it.
366 			 */
367 			break;
368 		default:
369 			n++;
370 			break;
371 		}
372 	}
373 
374 	e = (char *) ecalloc(n+1, sizeof(char));
375 
376 	/*
377 	 * Now copy the string, expanding any "%" or "#".
378 	 */
379 	to = e;
380 	for (fr = s;  *fr != '\0';  fr++)
381 	{
382 		switch (*fr)
383 		{
384 		case '%':
385 		case '#':
386 			if (fr > s && fr[-1] == *fr)
387 			{
388 				*to++ = *fr;
389 			} else if (fr[1] != *fr)
390 			{
391 				ifile = fchar_ifile(*fr);
392 				if (ifile == NULL_IFILE)
393 					*to++ = *fr;
394 				else
395 				{
396 					strcpy(to, get_filename(ifile));
397 					to += strlen(to);
398 				}
399 			}
400 			break;
401 		default:
402 			*to++ = *fr;
403 			break;
404 		}
405 	}
406 	*to = '\0';
407 	return (e);
408 }
409 
410 
411 #if TAB_COMPLETE_FILENAME
412 
413 /*
414  * Return a blank-separated list of filenames which "complete"
415  * the given string.
416  */
417 	public char *
fcomplete(s)418 fcomplete(s)
419 	char *s;
420 {
421 	char *fpat;
422 	char *qs;
423 
424 	if (secure)
425 		return (NULL);
426 	/*
427 	 * Complete the filename "s" by globbing "s*".
428 	 */
429 #if MSDOS_COMPILER && (MSDOS_COMPILER == MSOFTC || MSDOS_COMPILER == BORLANDC)
430 	/*
431 	 * But in DOS, we have to glob "s*.*".
432 	 * But if the final component of the filename already has
433 	 * a dot in it, just do "s*".
434 	 * (Thus, "FILE" is globbed as "FILE*.*",
435 	 *  but "FILE.A" is globbed as "FILE.A*").
436 	 */
437 	{
438 		char *slash;
439 		int len;
440 		for (slash = s+strlen(s)-1;  slash > s;  slash--)
441 			if (*slash == *PATHNAME_SEP || *slash == '/')
442 				break;
443 		len = strlen(s) + 4;
444 		fpat = (char *) ecalloc(len, sizeof(char));
445 		if (strchr(slash, '.') == NULL)
446 			SNPRINTF1(fpat, len, "%s*.*", s);
447 		else
448 			SNPRINTF1(fpat, len, "%s*", s);
449 	}
450 #else
451 	{
452 	int len = strlen(s) + 2;
453 	fpat = (char *) ecalloc(len, sizeof(char));
454 	SNPRINTF1(fpat, len, "%s*", s);
455 	}
456 #endif
457 	qs = lglob(fpat);
458 	s = shell_unquote(qs);
459 	if (strcmp(s,fpat) == 0)
460 	{
461 		/*
462 		 * The filename didn't expand.
463 		 */
464 		free(qs);
465 		qs = NULL;
466 	}
467 	free(s);
468 	free(fpat);
469 	return (qs);
470 }
471 #endif
472 
473 /*
474  * Try to determine if a file is "binary".
475  * This is just a guess, and we need not try too hard to make it accurate.
476  */
477 	public int
bin_file(f)478 bin_file(f)
479 	int f;
480 {
481 	int n;
482 	int bin_count = 0;
483 	char data[256];
484 	char* p;
485 	char* pend;
486 
487 	if (!seekable(f))
488 		return (0);
489 	if (lseek(f, (off_t)0, SEEK_SET) == BAD_LSEEK)
490 		return (0);
491 	n = read(f, data, sizeof(data));
492 	pend = &data[n];
493 	for (p = data;  p < pend;  )
494 	{
495 		LWCHAR c = step_char(&p, +1, pend);
496 		if (ctldisp == OPT_ONPLUS && IS_CSI_START(c))
497 		{
498 			do {
499 				c = step_char(&p, +1, pend);
500 			} while (p < pend && is_ansi_middle(c));
501 		} else if (binary_char(c))
502 			bin_count++;
503 	}
504 	/*
505 	 * Call it a binary file if there are more than 5 binary characters
506 	 * in the first 256 bytes of the file.
507 	 */
508 	return (bin_count > 5);
509 }
510 
511 /*
512  * Try to determine the size of a file by seeking to the end.
513  */
514 	static POSITION
seek_filesize(f)515 seek_filesize(f)
516 	int f;
517 {
518 	off_t spos;
519 
520 	spos = lseek(f, (off_t)0, SEEK_END);
521 	if (spos == BAD_LSEEK)
522 		return (NULL_POSITION);
523 	return ((POSITION) spos);
524 }
525 
526 /*
527  * Read a string from a file.
528  * Return a pointer to the string in memory.
529  */
530 	static char *
readfd(fd)531 readfd(fd)
532 	FILE *fd;
533 {
534 	int len;
535 	int ch;
536 	char *buf;
537 	char *p;
538 
539 	/*
540 	 * Make a guess about how many chars in the string
541 	 * and allocate a buffer to hold it.
542 	 */
543 	len = 100;
544 	buf = (char *) ecalloc(len, sizeof(char));
545 	for (p = buf;  ;  p++)
546 	{
547 		if ((ch = getc(fd)) == '\n' || ch == EOF)
548 			break;
549 		if (p - buf >= len-1)
550 		{
551 			/*
552 			 * The string is too big to fit in the buffer we have.
553 			 * Allocate a new buffer, twice as big.
554 			 */
555 			len *= 2;
556 			*p = '\0';
557 			p = (char *) ecalloc(len, sizeof(char));
558 			strcpy(p, buf);
559 			free(buf);
560 			buf = p;
561 			p = buf + strlen(buf);
562 		}
563 		*p = ch;
564 	}
565 	*p = '\0';
566 	return (buf);
567 }
568 
569 
570 
571 #if HAVE_POPEN
572 
573 FILE *popen();
574 
575 /*
576  * Execute a shell command.
577  * Return a pointer to a pipe connected to the shell command's standard output.
578  */
579 	static FILE *
shellcmd(cmd)580 shellcmd(cmd)
581 	char *cmd;
582 {
583 	FILE *fd;
584 
585 #if HAVE_SHELL
586 	char *shell;
587 
588 	shell = lgetenv("SHELL");
589 	if (shell != NULL && *shell != '\0')
590 	{
591 		char *scmd;
592 		char *esccmd;
593 
594 		/*
595 		 * Read the output of <$SHELL -c cmd>.
596 		 * Escape any metacharacters in the command.
597 		 */
598 		esccmd = shell_quote(cmd);
599 		if (esccmd == NULL)
600 		{
601 			fd = popen(cmd, "r");
602 		} else
603 		{
604 			int len = strlen(shell) + strlen(esccmd) + 5;
605 			scmd = (char *) ecalloc(len, sizeof(char));
606 			SNPRINTF3(scmd, len, "%s %s %s", shell, shell_coption(), esccmd);
607 			free(esccmd);
608 			fd = popen(scmd, "r");
609 			free(scmd);
610 		}
611 	} else
612 #endif
613 	{
614 		fd = popen(cmd, "r");
615 	}
616 	/*
617 	 * Redirection in `popen' might have messed with the
618 	 * standard devices.  Restore binary input mode.
619 	 */
620 	SET_BINARY(0);
621 	return (fd);
622 }
623 
624 #endif /* HAVE_POPEN */
625 
626 
627 /*
628  * Expand a filename, doing any system-specific metacharacter substitutions.
629  */
630 	public char *
lglob(filename)631 lglob(filename)
632 	char *filename;
633 {
634 	char *gfilename;
635 	char *ofilename;
636 
637 	ofilename = fexpand(filename);
638 	if (secure)
639 		return (ofilename);
640 	filename = shell_unquote(ofilename);
641 
642 #ifdef DECL_GLOB_LIST
643 {
644 	/*
645 	 * The globbing function returns a list of names.
646 	 */
647 	int length;
648 	char *p;
649 	char *qfilename;
650 	DECL_GLOB_LIST(list)
651 
652 	GLOB_LIST(filename, list);
653 	if (GLOB_LIST_FAILED(list))
654 	{
655 		free(filename);
656 		return (ofilename);
657 	}
658 	length = 1; /* Room for trailing null byte */
659 	for (SCAN_GLOB_LIST(list, p))
660 	{
661 		INIT_GLOB_LIST(list, p);
662 		qfilename = shell_quote(p);
663 		if (qfilename != NULL)
664 		{
665 	  		length += strlen(qfilename) + 1;
666 			free(qfilename);
667 		}
668 	}
669 	gfilename = (char *) ecalloc(length, sizeof(char));
670 	for (SCAN_GLOB_LIST(list, p))
671 	{
672 		INIT_GLOB_LIST(list, p);
673 		qfilename = shell_quote(p);
674 		if (qfilename != NULL)
675 		{
676 			sprintf(gfilename + strlen(gfilename), "%s ", qfilename);
677 			free(qfilename);
678 		}
679 	}
680 	/*
681 	 * Overwrite the final trailing space with a null terminator.
682 	 */
683 	*--p = '\0';
684 	GLOB_LIST_DONE(list);
685 }
686 #else
687 #ifdef DECL_GLOB_NAME
688 {
689 	/*
690 	 * The globbing function returns a single name, and
691 	 * is called multiple times to walk thru all names.
692 	 */
693 	register char *p;
694 	register int len;
695 	register int n;
696 	char *pathname;
697 	char *qpathname;
698 	DECL_GLOB_NAME(fnd,drive,dir,fname,ext,handle)
699 
700 	GLOB_FIRST_NAME(filename, &fnd, handle);
701 	if (GLOB_FIRST_FAILED(handle))
702 	{
703 		free(filename);
704 		return (ofilename);
705 	}
706 
707 	_splitpath(filename, drive, dir, fname, ext);
708 	len = 100;
709 	gfilename = (char *) ecalloc(len, sizeof(char));
710 	p = gfilename;
711 	do {
712 		n = strlen(drive) + strlen(dir) + strlen(fnd.GLOB_NAME) + 1;
713 		pathname = (char *) ecalloc(n, sizeof(char));
714 		SNPRINTF3(pathname, n, "%s%s%s", drive, dir, fnd.GLOB_NAME);
715 		qpathname = shell_quote(pathname);
716 		free(pathname);
717 		if (qpathname != NULL)
718 		{
719 			n = strlen(qpathname);
720 			while (p - gfilename + n + 2 >= len)
721 			{
722 				/*
723 				 * No room in current buffer.
724 				 * Allocate a bigger one.
725 				 */
726 				len *= 2;
727 				*p = '\0';
728 				p = (char *) ecalloc(len, sizeof(char));
729 				strcpy(p, gfilename);
730 				free(gfilename);
731 				gfilename = p;
732 				p = gfilename + strlen(gfilename);
733 			}
734 			strcpy(p, qpathname);
735 			free(qpathname);
736 			p += n;
737 			*p++ = ' ';
738 		}
739 	} while (GLOB_NEXT_NAME(handle, &fnd) == 0);
740 
741 	/*
742 	 * Overwrite the final trailing space with a null terminator.
743 	 */
744 	*--p = '\0';
745 	GLOB_NAME_DONE(handle);
746 }
747 #else
748 #if HAVE_POPEN
749 {
750 	/*
751 	 * We get the shell to glob the filename for us by passing
752 	 * an "echo" command to the shell and reading its output.
753 	 */
754 	FILE *fd;
755 	char *s;
756 	char *lessecho;
757 	char *cmd;
758 	char *esc;
759 	int len;
760 
761 	esc = get_meta_escape();
762 	if (strlen(esc) == 0)
763 		esc = "-";
764 	esc = shell_quote(esc);
765 	if (esc == NULL)
766 	{
767 		free(filename);
768 		return (ofilename);
769 	}
770 	lessecho = lgetenv("LESSECHO");
771 	if (lessecho == NULL || *lessecho == '\0')
772 		lessecho = "lessecho";
773 	/*
774 	 * Invoke lessecho, and read its output (a globbed list of filenames).
775 	 */
776 	len = strlen(lessecho) + strlen(ofilename) + (7*strlen(metachars())) + 24;
777 	cmd = (char *) ecalloc(len, sizeof(char));
778 	SNPRINTF4(cmd, len, "%s -p0x%x -d0x%x -e%s ", lessecho, openquote, closequote, esc);
779 	free(esc);
780 	for (s = metachars();  *s != '\0';  s++)
781 		sprintf(cmd + strlen(cmd), "-n0x%x ", *s);
782 	sprintf(cmd + strlen(cmd), "-- %s", ofilename);
783 	fd = shellcmd(cmd);
784 	free(cmd);
785 	if (fd == NULL)
786 	{
787 		/*
788 		 * Cannot create the pipe.
789 		 * Just return the original (fexpanded) filename.
790 		 */
791 		free(filename);
792 		return (ofilename);
793 	}
794 	gfilename = readfd(fd);
795 	pclose(fd);
796 	if (*gfilename == '\0')
797 	{
798 		free(gfilename);
799 		free(filename);
800 		return (ofilename);
801 	}
802 }
803 #else
804 	/*
805 	 * No globbing functions at all.  Just use the fexpanded filename.
806 	 */
807 	gfilename = save(filename);
808 #endif
809 #endif
810 #endif
811 	free(filename);
812 	free(ofilename);
813 	return (gfilename);
814 }
815 
816 /*
817  * Return number of %s escapes in a string.
818  * Return a large number if there are any other % escapes besides %s.
819  */
820 	static int
num_pct_s(lessopen)821 num_pct_s(lessopen)
822 	char *lessopen;
823 {
824 	int num;
825 
826 	for (num = 0;; num++)
827 	{
828 		lessopen = strchr(lessopen, '%');
829 		if (lessopen == NULL)
830 			break;
831 		if (*++lessopen != 's')
832 			return (999);
833 	}
834 	return (num);
835 }
836 
837 /*
838  * See if we should open a "replacement file"
839  * instead of the file we're about to open.
840  */
841 	public char *
open_altfile(filename,pf,pfd)842 open_altfile(filename, pf, pfd)
843 	char *filename;
844 	int *pf;
845 	void **pfd;
846 {
847 #if !HAVE_POPEN
848 	return (NULL);
849 #else
850 	char *lessopen;
851 	char *cmd;
852 	int len;
853 	FILE *fd;
854 #if HAVE_FILENO
855 	int returnfd = 0;
856 #endif
857 
858 	if (!use_lessopen || secure)
859 		return (NULL);
860 	ch_ungetchar(-1);
861 	if ((lessopen = lgetenv("LESSOPEN")) == NULL)
862 		return (NULL);
863 	while (*lessopen == '|')
864 	{
865 		/*
866 		 * If LESSOPEN starts with a |, it indicates
867 		 * a "pipe preprocessor".
868 		 */
869 #if !HAVE_FILENO
870 		error("LESSOPEN pipe is not supported", NULL_PARG);
871 		return (NULL);
872 #else
873 		lessopen++;
874 		returnfd++;
875 #endif
876 	}
877 	if (*lessopen == '-') {
878 		/*
879 		 * Lessopen preprocessor will accept "-" as a filename.
880 		 */
881 		lessopen++;
882 	} else {
883 		if (strcmp(filename, "-") == 0)
884 			return (NULL);
885 	}
886 	if (num_pct_s(lessopen) > 1)
887 	{
888 		error("Invalid LESSOPEN variable", NULL_PARG);
889 		return (NULL);
890 	}
891 
892 	len = strlen(lessopen) + strlen(filename) + 2;
893 	cmd = (char *) ecalloc(len, sizeof(char));
894 	SNPRINTF1(cmd, len, lessopen, filename);
895 	fd = shellcmd(cmd);
896 	free(cmd);
897 	if (fd == NULL)
898 	{
899 		/*
900 		 * Cannot create the pipe.
901 		 */
902 		return (NULL);
903 	}
904 #if HAVE_FILENO
905 	if (returnfd)
906 	{
907 		int f;
908 		char c;
909 
910 		/*
911 		 * Read one char to see if the pipe will produce any data.
912 		 * If it does, push the char back on the pipe.
913 		 */
914 		f = fileno(fd);
915 		SET_BINARY(f);
916 		if (read(f, &c, 1) != 1)
917 		{
918 			/*
919 			 * Pipe is empty.
920 			 * If more than 1 pipe char was specified,
921 			 * the exit status tells whether the file itself
922 			 * is empty, or if there is no alt file.
923 			 * If only one pipe char, just assume no alt file.
924 			 */
925 			int status = pclose(fd);
926 			if (returnfd > 1 && status == 0) {
927 				*pfd = NULL;
928 				*pf = -1;
929 				return (save(FAKE_EMPTYFILE));
930 			}
931 			return (NULL);
932 		}
933 		ch_ungetchar(c);
934 		*pfd = (void *) fd;
935 		*pf = f;
936 		return (save("-"));
937 	}
938 #endif
939 	cmd = readfd(fd);
940 	pclose(fd);
941 	if (*cmd == '\0')
942 		/*
943 		 * Pipe is empty.  This means there is no alt file.
944 		 */
945 		return (NULL);
946 	return (cmd);
947 #endif /* HAVE_POPEN */
948 }
949 
950 /*
951  * Close a replacement file.
952  */
953 	public void
close_altfile(altfilename,filename,pipefd)954 close_altfile(altfilename, filename, pipefd)
955 	char *altfilename;
956 	char *filename;
957 	void *pipefd;
958 {
959 #if HAVE_POPEN
960 	char *lessclose;
961 	FILE *fd;
962 	char *cmd;
963 	int len;
964 
965 	if (secure)
966 		return;
967 	if (pipefd != NULL)
968 	{
969 #if OS2
970 		/*
971 		 * The pclose function of OS/2 emx sometimes fails.
972 		 * Send SIGINT to the piped process before closing it.
973 		 */
974 		kill(((FILE*)pipefd)->_pid, SIGINT);
975 #endif
976 		pclose((FILE*) pipefd);
977 	}
978 	if ((lessclose = lgetenv("LESSCLOSE")) == NULL)
979 	     	return;
980 	if (num_pct_s(lessclose) > 2)
981 	{
982 		error("Invalid LESSCLOSE variable");
983 		return;
984 	}
985 	len = strlen(lessclose) + strlen(filename) + strlen(altfilename) + 2;
986 	cmd = (char *) ecalloc(len, sizeof(char));
987 	SNPRINTF2(cmd, len, lessclose, filename, altfilename);
988 	fd = shellcmd(cmd);
989 	free(cmd);
990 	if (fd != NULL)
991 		pclose(fd);
992 #endif
993 }
994 
995 /*
996  * Is the specified file a directory?
997  */
998 	public int
is_dir(filename)999 is_dir(filename)
1000 	char *filename;
1001 {
1002 	int isdir = 0;
1003 
1004 	filename = shell_unquote(filename);
1005 #if HAVE_STAT
1006 {
1007 	int r;
1008 	struct stat statbuf;
1009 
1010 	r = stat(filename, &statbuf);
1011 	isdir = (r >= 0 && S_ISDIR(statbuf.st_mode));
1012 }
1013 #else
1014 #ifdef _OSK
1015 {
1016 	register int f;
1017 
1018 	f = open(filename, S_IREAD | S_IFDIR);
1019 	if (f >= 0)
1020 		close(f);
1021 	isdir = (f >= 0);
1022 }
1023 #endif
1024 #endif
1025 	free(filename);
1026 	return (isdir);
1027 }
1028 
1029 /*
1030  * Returns NULL if the file can be opened and
1031  * is an ordinary file, otherwise an error message
1032  * (if it cannot be opened or is a directory, etc.)
1033  */
1034 	public char *
bad_file(filename)1035 bad_file(filename)
1036 	char *filename;
1037 {
1038 	register char *m = NULL;
1039 
1040 	filename = shell_unquote(filename);
1041 	if (!force_open && is_dir(filename))
1042 	{
1043 		static char is_a_dir[] = " is a directory";
1044 
1045 		m = (char *) ecalloc(strlen(filename) + sizeof(is_a_dir),
1046 			sizeof(char));
1047 		strcpy(m, filename);
1048 		strcat(m, is_a_dir);
1049 	} else
1050 	{
1051 #if HAVE_STAT
1052 		int r;
1053 		struct stat statbuf;
1054 
1055 		r = stat(filename, &statbuf);
1056 		if (r < 0)
1057 		{
1058 			m = errno_message(filename);
1059 		} else if (force_open)
1060 		{
1061 			m = NULL;
1062 		} else if (!S_ISREG(statbuf.st_mode))
1063 		{
1064 			static char not_reg[] = " is not a regular file (use -f to see it)";
1065 			m = (char *) ecalloc(strlen(filename) + sizeof(not_reg),
1066 				sizeof(char));
1067 			strcpy(m, filename);
1068 			strcat(m, not_reg);
1069 		}
1070 #endif
1071 	}
1072 	free(filename);
1073 	return (m);
1074 }
1075 
1076 /*
1077  * Return the size of a file, as cheaply as possible.
1078  * In Unix, we can stat the file.
1079  */
1080 	public POSITION
filesize(f)1081 filesize(f)
1082 	int f;
1083 {
1084 #if HAVE_STAT
1085 	struct stat statbuf;
1086 
1087 	if (fstat(f, &statbuf) >= 0)
1088 		return ((POSITION) statbuf.st_size);
1089 #else
1090 #ifdef _OSK
1091 	long size;
1092 
1093 	if ((size = (long) _gs_size(f)) >= 0)
1094 		return ((POSITION) size);
1095 #endif
1096 #endif
1097 	return (seek_filesize(f));
1098 }
1099 
1100 /*
1101  *
1102  */
1103 	public char *
shell_coption()1104 shell_coption()
1105 {
1106 	return ("-c");
1107 }
1108 
1109 /*
1110  * Return last component of a pathname.
1111  */
1112 	public char *
last_component(name)1113 last_component(name)
1114 	char *name;
1115 {
1116 	char *slash;
1117 
1118 	for (slash = name + strlen(name);  slash > name; )
1119 	{
1120 		--slash;
1121 		if (*slash == *PATHNAME_SEP || *slash == '/')
1122 			return (slash + 1);
1123 	}
1124 	return (name);
1125 }
1126 
1127