xref: /netbsd-src/bin/csh/csh.c (revision ee9e50eacb51d94f3805922fba5e3f338e0e4691)
1 /*	$NetBSD: csh.c,v 1.24 1998/07/28 11:41:41 mycroft Exp $	*/
2 
3 /*-
4  * Copyright (c) 1980, 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 #ifndef lint
38 __COPYRIGHT("@(#) Copyright (c) 1980, 1991, 1993\n\
39 	The Regents of the University of California.  All rights reserved.\n");
40 #endif /* not lint */
41 
42 #ifndef lint
43 #if 0
44 static char sccsid[] = "@(#)csh.c	8.2 (Berkeley) 10/12/93";
45 #else
46 __RCSID("$NetBSD: csh.c,v 1.24 1998/07/28 11:41:41 mycroft Exp $");
47 #endif
48 #endif /* not lint */
49 
50 #include <sys/types.h>
51 #include <sys/ioctl.h>
52 #include <sys/stat.h>
53 #include <fcntl.h>
54 #include <errno.h>
55 #include <pwd.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <time.h>
59 #include <locale.h>
60 #include <unistd.h>
61 #include <vis.h>
62 #include <paths.h>	/* should this be included in pathnames.h instead? */
63 #if __STDC__
64 # include <stdarg.h>
65 #else
66 # include <varargs.h>
67 #endif
68 
69 #include "csh.h"
70 #include "proc.h"
71 #include "extern.h"
72 #include "pathnames.h"
73 
74 /*
75  * C Shell
76  *
77  * Bill Joy, UC Berkeley, California, USA
78  * October 1978, May 1980
79  *
80  * Jim Kulp, IIASA, Laxenburg, Austria
81  * April 1980
82  *
83  * Christos Zoulas, Cornell University
84  * June, 1991
85  */
86 
87 Char   *dumphist[] = {STRhistory, STRmh, 0, 0};
88 Char   *loadhist[] = {STRsource, STRmh, STRtildothist, 0};
89 
90 int     nofile = 0;
91 bool    reenter = 0;
92 bool    nverbose = 0;
93 bool    nexececho = 0;
94 bool    quitit = 0;
95 bool    fast = 0;
96 bool    batch = 0;
97 bool    mflag = 0;
98 bool    prompt = 1;
99 bool    enterhist = 0;
100 
101 extern char **environ;
102 
103 static int	readf __P((void *, char *, int));
104 static fpos_t	seekf __P((void *, fpos_t, int));
105 static int	writef __P((void *, const char *, int));
106 static int	closef __P((void *));
107 static int	srccat __P((Char *, Char *));
108 static int	srcfile __P((char *, bool, bool));
109 static void	phup __P((int));
110 static void	srcunit __P((int, bool, bool));
111 static void	mailchk __P((void));
112 #ifndef _PATH_DEFPATH
113 static Char   **defaultpath __P((void));
114 #endif
115 
116 int main __P((int, char **));
117 
118 int
119 main(argc, argv)
120     int     argc;
121     char  **argv;
122 {
123     Char *cp;
124     char *tcp;
125     const char *ecp;
126     int f;
127     char **tempv;
128     struct sigaction oact;
129     sigset_t sigset;
130 
131     cshin = stdin;
132     cshout = stdout;
133     csherr = stderr;
134 
135     settimes();			/* Immed. estab. timing base */
136 
137     /*
138      * Initialize non constant strings
139      */
140 #ifdef _PATH_BSHELL
141     STR_BSHELL = SAVE(_PATH_BSHELL);
142 #endif
143 #ifdef _PATH_CSHELL
144     STR_SHELLPATH = SAVE(_PATH_CSHELL);
145 #endif
146     STR_environ = blk2short(environ);
147     environ = short2blk(STR_environ);	/* So that we can free it */
148     STR_WORD_CHARS = SAVE(WORD_CHARS);
149 
150     HIST = '!';
151     HISTSUB = '^';
152     word_chars = STR_WORD_CHARS;
153 
154     tempv = argv;
155     if (eq(str2short(tempv[0]), STRaout))	/* A.out's are quittable */
156 	quitit = 1;
157     uid = getuid();
158     gid = getgid();
159     euid = geteuid();
160     egid = getegid();
161     /*
162      * We are a login shell if: 1. we were invoked as -<something> and we had
163      * no arguments 2. or we were invoked only with the -l flag
164      */
165     loginsh = (**tempv == '-' && argc == 1) ||
166 	(argc == 2 && tempv[1][0] == '-' && tempv[1][1] == 'l' &&
167 	 tempv[1][2] == '\0');
168 
169     if (loginsh && **tempv != '-') {
170 	/*
171 	 * Mangle the argv space
172 	 */
173 	tempv[1][0] = '\0';
174 	tempv[1][1] = '\0';
175 	tempv[1] = NULL;
176 	for (tcp = *tempv; *tcp++;)
177 	    continue;
178 	for (tcp--; tcp >= *tempv; tcp--)
179 	    tcp[1] = tcp[0];
180 	*++tcp = '-';
181 	argc--;
182     }
183     if (loginsh)
184 	(void) time(&chktim);
185 
186     AsciiOnly = 1;
187 #ifdef NLS
188     (void) setlocale(LC_ALL, "");
189     {
190 	int     k;
191 
192 	for (k = 0200; k <= 0377 && !Isprint(k); k++)
193 	    continue;
194 	AsciiOnly = k > 0377;
195     }
196 #else
197     AsciiOnly = getenv("LANG") == NULL && getenv("LC_CTYPE") == NULL;
198 #endif				/* NLS */
199 
200     /*
201      * Move the descriptors to safe places. The variable didfds is 0 while we
202      * have only FSH* to work with. When didfds is true, we have 0,1,2 and
203      * prefer to use these.
204      */
205     initdesc();
206     /*
207      * XXX: This is to keep programs that use stdio happy.
208      *	    what we really want is freunopen() ....
209      *	    Closing cshin cshout and csherr (which are really stdin stdout
210      *	    and stderr at this point and then reopening them in the same order
211      *	    gives us again stdin == cshin stdout == cshout and stderr == csherr.
212      *	    If that was not the case builtins like printf that use stdio
213      *	    would break. But in any case we could fix that with memcpy and
214      *	    a bit of pointer manipulation...
215      *	    Fortunately this is not needed under the current implementation
216      *	    of stdio.
217      */
218     (void) fclose(cshin);
219     (void) fclose(cshout);
220     (void) fclose(csherr);
221     if (!(cshin  = funopen((void *) &SHIN,  readf, writef, seekf, closef)))
222 	exit(1);
223     if (!(cshout = funopen((void *) &SHOUT, readf, writef, seekf, closef)))
224 	exit(1);
225     if (!(csherr = funopen((void *) &SHERR, readf, writef, seekf, closef)))
226 	exit(1);
227     (void) setvbuf(cshin,  NULL, _IOLBF, 0);
228     (void) setvbuf(cshout, NULL, _IOLBF, 0);
229     (void) setvbuf(csherr, NULL, _IOLBF, 0);
230 
231     /*
232      * Initialize the shell variables. ARGV and PROMPT are initialized later.
233      * STATUS is also munged in several places. CHILD is munged when
234      * forking/waiting
235      */
236     set(STRstatus, Strsave(STR0));
237 
238     if ((ecp = getenv("HOME")) != NULL)
239 	cp = quote(SAVE(ecp));
240     else
241 	cp = NULL;
242 
243     if (cp == NULL)
244 	fast = 1;		/* No home -> can't read scripts */
245     else
246 	set(STRhome, cp);
247     dinit(cp);			/* dinit thinks that HOME == cwd in a login
248 				 * shell */
249     /*
250      * Grab other useful things from the environment. Should we grab
251      * everything??
252      */
253     if ((ecp = getenv("LOGNAME")) != NULL ||
254 	(ecp = getenv("USER")) != NULL)
255 	set(STRuser, quote(SAVE(ecp)));
256     if ((ecp = getenv("TERM")) != NULL)
257 	set(STRterm, quote(SAVE(ecp)));
258 
259     /*
260      * Re-initialize path if set in environment
261      */
262     if ((ecp = getenv("PATH")) == NULL) {
263 #ifdef _PATH_DEFPATH
264 	importpath(SAVE(_PATH_DEFPATH));
265 #else
266 	setq(STRpath, defaultpath(), &shvhed);
267 #endif
268     } else {
269 	importpath(SAVE(ecp));
270     }
271 
272     set(STRshell, Strsave(STR_SHELLPATH));
273 
274     doldol = putn((int) getpid());	/* For $$ */
275     shtemp = Strspl(STRtmpsh, doldol);	/* For << */
276 
277     /*
278      * Record the interrupt states from the parent process. If the parent is
279      * non-interruptible our hand must be forced or we (and our children) won't
280      * be either. Our children inherit termination from our parent. We catch it
281      * only if we are the login shell.
282      */
283     /* parents interruptibility */
284     (void) sigaction(SIGINT, NULL, &oact);
285     parintr = oact.sa_handler;
286     (void) sigaction(SIGTERM, NULL, &oact);
287     parterm = oact.sa_handler;
288 
289     /* catch these all, login shell or not */
290     (void) signal(SIGHUP, phup);	/* exit processing on HUP */
291     (void) signal(SIGXCPU, phup);	/* ...and on XCPU */
292     (void) signal(SIGXFSZ, phup);	/* ...and on XFSZ */
293 
294     /*
295      * Process the arguments.
296      *
297      * Note that processing of -v/-x is actually delayed till after script
298      * processing.
299      *
300      * We set the first character of our name to be '-' if we are a shell
301      * running interruptible commands.  Many programs which examine ps'es
302      * use this to filter such shells out.
303      */
304     argc--, tempv++;
305     while (argc > 0 && (tcp = tempv[0])[0] == '-' && *++tcp != '\0' && !batch) {
306 	do
307 	    switch (*tcp++) {
308 
309 	    case 0:		/* -	Interruptible, no prompt */
310 		prompt = 0;
311 		setintr = 1;
312 		nofile = 1;
313 		break;
314 
315 	    case 'b':		/* -b	Next arg is input file */
316 		batch = 1;
317 		break;
318 
319 	    case 'c':		/* -c	Command input from arg */
320 		if (argc == 1)
321 		    xexit(0);
322 		argc--, tempv++;
323 		arginp = SAVE(tempv[0]);
324 		prompt = 0;
325 		nofile = 1;
326 		break;
327 
328 	    case 'e':		/* -e	Exit on any error */
329 		exiterr = 1;
330 		break;
331 
332 	    case 'f':		/* -f	Fast start */
333 		fast = 1;
334 		break;
335 
336 	    case 'i':		/* -i	Interactive, even if !intty */
337 		intact = 1;
338 		nofile = 1;
339 		break;
340 
341 	    case 'm':		/* -m	read .cshrc (from su) */
342 		mflag = 1;
343 		break;
344 
345 	    case 'n':		/* -n	Don't execute */
346 		noexec = 1;
347 		break;
348 
349 	    case 'q':		/* -q	(Undoc'd) ... die on quit */
350 		quitit = 1;
351 		break;
352 
353 	    case 's':		/* -s	Read from std input */
354 		nofile = 1;
355 		break;
356 
357 	    case 't':		/* -t	Read one line from input */
358 		onelflg = 2;
359 		prompt = 0;
360 		nofile = 1;
361 		break;
362 
363 	    case 'v':		/* -v	Echo hist expanded input */
364 		nverbose = 1;	/* ... later */
365 		break;
366 
367 	    case 'x':		/* -x	Echo just before execution */
368 		nexececho = 1;	/* ... later */
369 		break;
370 
371 	    case 'V':		/* -V	Echo hist expanded input */
372 		setNS(STRverbose);	/* NOW! */
373 		break;
374 
375 	    case 'X':		/* -X	Echo just before execution */
376 		setNS(STRecho);	/* NOW! */
377 		break;
378 
379 	} while (*tcp);
380 	tempv++, argc--;
381     }
382 
383     if (quitit)			/* With all due haste, for debugging */
384 	(void) signal(SIGQUIT, SIG_DFL);
385 
386     /*
387      * Unless prevented by -, -c, -i, -s, or -t, if there are remaining
388      * arguments the first of them is the name of a shell file from which to
389      * read commands.
390      */
391     if (nofile == 0 && argc > 0) {
392 	nofile = open(tempv[0], O_RDONLY);
393 	if (nofile < 0) {
394 	    child = 1;		/* So this doesn't return */
395 	    stderror(ERR_SYSTEM, tempv[0], strerror(errno));
396 	}
397 	ffile = SAVE(tempv[0]);
398 	/*
399 	 * Replace FSHIN. Handle /dev/std{in,out,err} specially
400 	 * since once they are closed we cannot open them again.
401 	 * In that case we use our own saved descriptors
402 	 */
403 	if ((SHIN = dmove(nofile, FSHIN)) < 0)
404 	    switch(nofile) {
405 	    case 0:
406 		SHIN = FSHIN;
407 		break;
408 	    case 1:
409 		SHIN = FSHOUT;
410 		break;
411 	    case 2:
412 		SHIN = FSHERR;
413 		break;
414 	    default:
415 		stderror(ERR_SYSTEM, tempv[0], strerror(errno));
416 		/* NOTREACHED */
417 	    }
418 	(void) ioctl(SHIN, FIOCLEX, NULL);
419 	prompt = 0;
420 	 /* argc not used any more */ tempv++;
421     }
422 
423     intty = isatty(SHIN);
424     intty |= intact;
425     if (intty || (intact && isatty(SHOUT))) {
426 	if (!batch && (uid != euid || gid != egid)) {
427 	    errno = EACCES;
428 	    child = 1;		/* So this doesn't return */
429 	    stderror(ERR_SYSTEM, "csh", strerror(errno));
430 	}
431     }
432     /*
433      * Decide whether we should play with signals or not. If we are explicitly
434      * told (via -i, or -) or we are a login shell (arg0 starts with -) or the
435      * input and output are both the ttys("csh", or "csh</dev/ttyx>/dev/ttyx")
436      * Note that in only the login shell is it likely that parent may have set
437      * signals to be ignored
438      */
439     if (loginsh || intact || (intty && isatty(SHOUT)))
440 	setintr = 1;
441     settell();
442     /*
443      * Save the remaining arguments in argv.
444      */
445     setq(STRargv, blk2short(tempv), &shvhed);
446 
447     /*
448      * Set up the prompt.
449      */
450     if (prompt) {
451 	set(STRprompt, Strsave(uid == 0 ? STRsymhash : STRsymcent));
452 	/* that's a meta-questionmark */
453 	set(STRprompt2, Strsave(STRmquestion));
454     }
455 
456     /*
457      * If we are an interactive shell, then start fiddling with the signals;
458      * this is a tricky game.
459      */
460     shpgrp = getpgrp();
461     opgrp = tpgrp = -1;
462     if (setintr) {
463 	**argv = '-';
464 	if (!quitit)		/* Wary! */
465 	    (void) signal(SIGQUIT, SIG_IGN);
466 	(void) signal(SIGINT, pintr);
467 	sigemptyset(&sigset);
468 	(void) sigaddset(&sigset, SIGINT);
469 	(void) sigprocmask(SIG_BLOCK, &sigset, NULL);
470 	(void) signal(SIGTERM, SIG_IGN);
471 	if (quitit == 0 && arginp == 0) {
472 	    (void) signal(SIGTSTP, SIG_IGN);
473 	    (void) signal(SIGTTIN, SIG_IGN);
474 	    (void) signal(SIGTTOU, SIG_IGN);
475 	    /*
476 	     * Wait till in foreground, in case someone stupidly runs csh &
477 	     * dont want to try to grab away the tty.
478 	     */
479 	    if (isatty(FSHERR))
480 		f = FSHERR;
481 	    else if (isatty(FSHOUT))
482 		f = FSHOUT;
483 	    else if (isatty(OLDSTD))
484 		f = OLDSTD;
485 	    else
486 		f = -1;
487     retry:
488 	    if ((tpgrp = tcgetpgrp(f)) != -1) {
489 		if (tpgrp != shpgrp) {
490 		    sig_t old = signal(SIGTTIN, SIG_DFL);
491 		    (void) kill(0, SIGTTIN);
492 		    (void) signal(SIGTTIN, old);
493 		    goto retry;
494 		}
495 		opgrp = shpgrp;
496 		shpgrp = getpid();
497 		tpgrp = shpgrp;
498 		/*
499 		 * Setpgid will fail if we are a session leader and
500 		 * mypid == mypgrp (POSIX 4.3.3)
501 		 */
502 		if (opgrp != shpgrp)
503 		    if (setpgid(0, shpgrp) == -1)
504 			goto notty;
505 		/*
506 		 * We do that after we set our process group, to make sure
507 		 * that the process group belongs to a process in the same
508 		 * session as the tty (our process and our group) (POSIX 7.2.4)
509 		 */
510 		if (tcsetpgrp(f, shpgrp) == -1)
511 		    goto notty;
512 		(void) ioctl(dcopy(f, FSHTTY), FIOCLEX, NULL);
513 	    }
514 	    if (tpgrp == -1) {
515 notty:
516 		(void) fprintf(csherr, "Warning: no access to tty (%s).\n",
517 			       strerror(errno));
518 		(void) fprintf(csherr, "Thus no job control in this shell.\n");
519 	    }
520 	}
521     }
522     if ((setintr == 0) && (parintr == SIG_DFL))
523 	setintr = 1;
524     (void) signal(SIGCHLD, pchild);	/* while signals not ready */
525 
526     /*
527      * Set an exit here in case of an interrupt or error reading the shell
528      * start-up scripts.
529      */
530     reenter = setexit();	/* PWP */
531     haderr = 0;			/* In case second time through */
532     if (!fast && reenter == 0) {
533 	/* Will have value(STRhome) here because set fast if don't */
534 	{
535 	    int     osetintr = setintr;
536 	    sig_t   oparintr = parintr;
537 	    sigset_t osigset;
538 
539 	    sigemptyset(&sigset);
540 	    (void) sigaddset(&sigset, SIGINT);
541 	    (void) sigprocmask(SIG_BLOCK, &sigset, &osigset);
542 
543 	    setintr = 0;
544 	    parintr = SIG_IGN;	/* Disable onintr */
545 #ifdef _PATH_DOTCSHRC
546 	    (void) srcfile(_PATH_DOTCSHRC, 0, 0);
547 #endif
548 	    if (!fast && !arginp && !onelflg)
549 		dohash(NULL, NULL);
550 #ifdef _PATH_DOTLOGIN
551 	    if (loginsh)
552 		(void) srcfile(_PATH_DOTLOGIN, 0, 0);
553 #endif
554 	    (void) sigprocmask(SIG_SETMASK, &osigset, NULL);
555 	    setintr = osetintr;
556 	    parintr = oparintr;
557 	}
558 	(void) srccat(value(STRhome), STRsldotcshrc);
559 
560 	if (!fast && !arginp && !onelflg && !havhash)
561 	    dohash(NULL, NULL);
562 	/*
563 	 * Source history before .login so that it is available in .login
564 	 */
565 	if ((cp = value(STRhistfile)) != STRNULL)
566 	    loadhist[2] = cp;
567 	dosource(loadhist, NULL);
568         if (loginsh)
569 	      (void) srccat(value(STRhome), STRsldotlogin);
570     }
571 
572     /*
573      * Now are ready for the -v and -x flags
574      */
575     if (nverbose)
576 	setNS(STRverbose);
577     if (nexececho)
578 	setNS(STRecho);
579 
580     /*
581      * All the rest of the world is inside this call. The argument to process
582      * indicates whether it should catch "error unwinds".  Thus if we are a
583      * interactive shell our call here will never return by being blown past on
584      * an error.
585      */
586     process(setintr);
587 
588     /*
589      * Mop-up.
590      */
591     if (intty) {
592 	if (loginsh) {
593 	    (void) fprintf(cshout, "logout\n");
594 	    (void) close(SHIN);
595 	    child = 1;
596 	    goodbye();
597 	}
598 	else {
599 	    (void) fprintf(cshout, "exit\n");
600 	}
601     }
602     rechist();
603     exitstat();
604     /* NOTREACHED */
605 }
606 
607 void
608 untty()
609 {
610     if (tpgrp > 0) {
611 	(void) setpgid(0, opgrp);
612 	(void) tcsetpgrp(FSHTTY, opgrp);
613     }
614 }
615 
616 void
617 importpath(cp)
618     Char   *cp;
619 {
620     int i = 0;
621     Char *dp;
622     Char **pv;
623     int     c;
624 
625     for (dp = cp; *dp; dp++)
626 	if (*dp == ':')
627 	    i++;
628     /*
629      * i+2 where i is the number of colons in the path. There are i+1
630      * directories in the path plus we need room for a zero terminator.
631      */
632     pv = (Char **) xcalloc((size_t) (i + 2), sizeof(Char **));
633     dp = cp;
634     i = 0;
635     if (*dp)
636 	for (;;) {
637 	    if ((c = *dp) == ':' || c == 0) {
638 		*dp = 0;
639 		pv[i++] = Strsave(*cp ? cp : STRdot);
640 		if (c) {
641 		    cp = dp + 1;
642 		    *dp = ':';
643 		}
644 		else
645 		    break;
646 	    }
647 	    dp++;
648 	}
649     pv[i] = 0;
650     set1(STRpath, pv, &shvhed);
651 }
652 
653 /*
654  * Source to the file which is the catenation of the argument names.
655  */
656 static int
657 srccat(cp, dp)
658     Char   *cp, *dp;
659 {
660     Char *ep = Strspl(cp, dp);
661     char   *ptr = short2str(ep);
662 
663     xfree((ptr_t) ep);
664     return srcfile(ptr, mflag ? 0 : 1, 0);
665 }
666 
667 /*
668  * Source to a file putting the file descriptor in a safe place (> 2).
669  */
670 static int
671 srcfile(f, onlyown, flag)
672     char   *f;
673     bool    onlyown, flag;
674 {
675     int unit;
676 
677     if ((unit = open(f, O_RDONLY)) == -1)
678 	return 0;
679     unit = dmove(unit, -1);
680 
681     (void) ioctl(unit, FIOCLEX, NULL);
682     srcunit(unit, onlyown, flag);
683     return 1;
684 }
685 
686 /*
687  * Source to a unit.  If onlyown it must be our file or our group or
688  * we don't chance it.	This occurs on ".cshrc"s and the like.
689  */
690 int     insource;
691 static void
692 srcunit(unit, onlyown, hflg)
693     int unit;
694     bool    onlyown, hflg;
695 {
696     /* We have to push down a lot of state here */
697     /* All this could go into a structure */
698     int     oSHIN = -1, oldintty = intty, oinsource = insource;
699     struct whyle *oldwhyl = whyles;
700     Char   *ogointr = gointr, *oarginp = arginp;
701     Char   *oevalp = evalp, **oevalvec = evalvec;
702     int     oonelflg = onelflg;
703     bool    oenterhist = enterhist;
704     char    OHIST = HIST;
705     bool    otell = cantell;
706 
707     struct Bin saveB;
708     sigset_t sigset, osigset;
709     jmp_buf oldexit;
710 
711     /* The (few) real local variables */
712     int     my_reenter;
713 
714     if (unit < 0)
715 	return;
716     if (didfds)
717 	donefds();
718     if (onlyown) {
719 	struct stat stb;
720 
721 	if (fstat(unit, &stb) < 0) {
722 	    (void) close(unit);
723 	    return;
724 	}
725     }
726 
727     /*
728      * There is a critical section here while we are pushing down the input
729      * stream since we have stuff in different structures. If we weren't
730      * careful an interrupt could corrupt SHIN's Bin structure and kill the
731      * shell.
732      *
733      * We could avoid the critical region by grouping all the stuff in a single
734      * structure and pointing at it to move it all at once.  This is less
735      * efficient globally on many variable references however.
736      */
737     insource = 1;
738     getexit(oldexit);
739 
740     if (setintr) {
741 	sigemptyset(&sigset);
742 	(void) sigaddset(&sigset, SIGINT);
743 	(void) sigprocmask(SIG_BLOCK, &sigset, &osigset);
744     }
745     /* Setup the new values of the state stuff saved above */
746     (void) memcpy(&saveB, &B, sizeof(B));
747     fbuf = NULL;
748     fseekp = feobp = fblocks = 0;
749     oSHIN = SHIN, SHIN = unit, arginp = 0, onelflg = 0;
750     intty = isatty(SHIN), whyles = 0, gointr = 0;
751     evalvec = 0;
752     evalp = 0;
753     enterhist = hflg;
754     if (enterhist)
755 	HIST = '\0';
756 
757     /*
758      * Now if we are allowing commands to be interrupted, we let ourselves be
759      * interrupted.
760      */
761     if (setintr)
762 	(void) sigprocmask(SIG_SETMASK, &osigset, NULL);
763     settell();
764 
765     if ((my_reenter = setexit()) == 0)
766 	process(0);		/* 0 -> blow away on errors */
767 
768     if (setintr)
769 	(void) sigprocmask(SIG_SETMASK, &osigset, NULL);
770     if (oSHIN >= 0) {
771 	int i;
772 
773 	/* We made it to the new state... free up its storage */
774 	/* This code could get run twice but xfree doesn't care */
775 	for (i = 0; i < fblocks; i++)
776 	    xfree((ptr_t) fbuf[i]);
777 	xfree((ptr_t) fbuf);
778 
779 	/* Reset input arena */
780 	(void) memcpy(&B, &saveB, sizeof(B));
781 
782 	(void) close(SHIN), SHIN = oSHIN;
783 	arginp = oarginp, onelflg = oonelflg;
784 	evalp = oevalp, evalvec = oevalvec;
785 	intty = oldintty, whyles = oldwhyl, gointr = ogointr;
786 	if (enterhist)
787 	    HIST = OHIST;
788 	enterhist = oenterhist;
789 	cantell = otell;
790     }
791 
792     resexit(oldexit);
793     /*
794      * If process reset() (effectively an unwind) then we must also unwind.
795      */
796     if (my_reenter)
797 	stderror(ERR_SILENT);
798     insource = oinsource;
799 }
800 
801 void
802 rechist()
803 {
804     Char    buf[BUFSIZ], hbuf[BUFSIZ], *hfile;
805     int     fp, ftmp, oldidfds;
806     struct  varent *shist;
807 
808     if (!fast) {
809 	/*
810 	 * If $savehist is just set, we use the value of $history
811 	 * else we use the value in $savehist
812 	 */
813 	if ((shist = adrof(STRsavehist)) != NULL) {
814 	    if (shist->vec[0][0] != '\0')
815 		(void) Strcpy(hbuf, shist->vec[0]);
816 	    else if ((shist = adrof(STRhistory)) && shist->vec[0][0] != '\0')
817 		(void) Strcpy(hbuf, shist->vec[0]);
818 	    else
819 		return;
820 	}
821 	else
822   	    return;
823 
824   	if ((hfile = value(STRhistfile)) == STRNULL) {
825   	    hfile = Strcpy(buf, value(STRhome));
826   	    (void) Strcat(buf, STRsldthist);
827   	}
828 
829   	if ((fp = open(short2str(hfile), O_WRONLY | O_CREAT | O_TRUNC,
830 	    0600)) == -1)
831   	    return;
832 
833 	oldidfds = didfds;
834 	didfds = 0;
835 	ftmp = SHOUT;
836 	SHOUT = fp;
837 	dumphist[2] = hbuf;
838 	dohist(dumphist, NULL);
839 	SHOUT = ftmp;
840 	(void) close(fp);
841 	didfds = oldidfds;
842     }
843 }
844 
845 void
846 goodbye()
847 {
848     rechist();
849 
850     if (loginsh) {
851 	(void) signal(SIGQUIT, SIG_IGN);
852 	(void) signal(SIGINT, SIG_IGN);
853 	(void) signal(SIGTERM, SIG_IGN);
854 	setintr = 0;		/* No interrupts after "logout" */
855 	if (!(adrof(STRlogout)))
856 	    set(STRlogout, STRnormal);
857 #ifdef _PATH_DOTLOGOUT
858 	(void) srcfile(_PATH_DOTLOGOUT, 0, 0);
859 #endif
860 	if (adrof(STRhome))
861 	    (void) srccat(value(STRhome), STRsldtlogout);
862     }
863     exitstat();
864     /* NOTREACHED */
865 }
866 
867 __dead void
868 exitstat()
869 {
870     Char *s;
871 #ifdef PROF
872     monitor(0);
873 #endif
874     /*
875      * Note that if STATUS is corrupted (i.e. getn bombs) then error will exit
876      * directly because we poke child here. Otherwise we might continue
877      * unwarrantedly (sic).
878      */
879     child = 1;
880     s = value(STRstatus);
881     xexit(s ? getn(s) : 0);
882     /* NOTREACHED */
883 }
884 
885 /*
886  * in the event of a HUP we want to save the history
887  */
888 static void
889 phup(sig)
890 int sig;
891 {
892     rechist();
893 
894     /*
895      * We kill the last foreground process group. It then becomes
896      * responsible to propagate the SIGHUP to its progeny.
897      */
898     {
899 	struct process *pp, *np;
900 
901 	for (pp = proclist.p_next; pp; pp = pp->p_next) {
902 	    np = pp;
903 	    /*
904 	     * Find if this job is in the foreground. It could be that
905 	     * the process leader has exited and the foreground flag
906 	     * is cleared for it.
907 	     */
908 	    do
909 		/*
910 		 * If a process is in the foreground; we try to kill
911 		 * it's process group. If we succeed, then the
912 		 * whole job is gone. Otherwise we keep going...
913 		 * But avoid sending HUP to the shell again.
914 		 */
915 		if ((np->p_flags & PFOREGND) != 0 && np->p_jobid != shpgrp &&
916 		    kill(-np->p_jobid, SIGHUP) != -1) {
917 		    /* In case the job was suspended... */
918 		    (void) kill(-np->p_jobid, SIGCONT);
919 		    break;
920 		}
921 	    while ((np = np->p_friends) != pp);
922 	}
923     }
924     xexit(sig);
925     /* NOTREACHED */
926 }
927 
928 Char   *jobargv[2] = {STRjobs, 0};
929 
930 /*
931  * Catch an interrupt, e.g. during lexical input.
932  * If we are an interactive shell, we reset the interrupt catch
933  * immediately.  In any case we drain the shell output,
934  * and finally go through the normal error mechanism, which
935  * gets a chance to make the shell go away.
936  */
937 /* ARGSUSED */
938 void
939 pintr(notused)
940 	int notused;
941 {
942     pintr1(1);
943     /* NOTREACHED */
944 }
945 
946 void
947 pintr1(wantnl)
948     bool    wantnl;
949 {
950     Char **v;
951     sigset_t sigset, osigset;
952 
953     sigemptyset(&sigset);
954     (void) sigprocmask(SIG_BLOCK, &sigset, &osigset);
955     if (setintr) {
956 	sigset = osigset;
957 	(void) sigdelset(&sigset, SIGINT);
958 	(void) sigprocmask(SIG_SETMASK, &sigset, NULL);
959 	if (pjobs) {
960 	    pjobs = 0;
961 	    (void) fprintf(cshout, "\n");
962 	    dojobs(jobargv, NULL);
963 	    stderror(ERR_NAME | ERR_INTR);
964 	}
965     }
966     (void) sigdelset(&osigset, SIGCHLD);
967     (void) sigprocmask(SIG_SETMASK, &osigset, NULL);
968     (void) fpurge(cshout);
969     (void) endpwent();
970 
971     /*
972      * If we have an active "onintr" then we search for the label. Note that if
973      * one does "onintr -" then we shan't be interruptible so we needn't worry
974      * about that here.
975      */
976     if (gointr) {
977 	gotolab(gointr);
978 	timflg = 0;
979 	if ((v = pargv) != NULL)
980 	    pargv = 0, blkfree(v);
981 	if ((v = gargv) != NULL)
982 	    gargv = 0, blkfree(v);
983 	reset();
984     }
985     else if (intty && wantnl) {
986 	(void) fputc('\r', cshout);
987 	(void) fputc('\n', cshout);
988     }
989     stderror(ERR_SILENT);
990     /* NOTREACHED */
991 }
992 
993 /*
994  * Process is the main driving routine for the shell.
995  * It runs all command processing, except for those within { ... }
996  * in expressions (which is run by a routine evalav in sh.exp.c which
997  * is a stripped down process), and `...` evaluation which is run
998  * also by a subset of this code in sh.glob.c in the routine backeval.
999  *
1000  * The code here is a little strange because part of it is interruptible
1001  * and hence freeing of structures appears to occur when none is necessary
1002  * if this is ignored.
1003  *
1004  * Note that if catch is not set then we will unwind on any error.
1005  * If an end-of-file occurs, we return.
1006  */
1007 static struct command *savet = NULL;
1008 void
1009 process(catch)
1010     bool    catch;
1011 {
1012     jmp_buf osetexit;
1013     struct command *t = savet;
1014     sigset_t sigset;
1015 
1016     savet = NULL;
1017     getexit(osetexit);
1018     for (;;) {
1019 	pendjob();
1020 	paraml.next = paraml.prev = &paraml;
1021 	paraml.word = STRNULL;
1022 	(void) setexit();
1023 	justpr = enterhist;	/* execute if not entering history */
1024 
1025 	/*
1026 	 * Interruptible during interactive reads
1027 	 */
1028 	if (setintr) {
1029 	    sigemptyset(&sigset);
1030 	    (void) sigaddset(&sigset, SIGINT);
1031 	    (void) sigprocmask(SIG_UNBLOCK, &sigset, NULL);
1032 	}
1033 
1034 	/*
1035 	 * For the sake of reset()
1036 	 */
1037 	freelex(&paraml);
1038 	if (savet)
1039 	    freesyn(savet), savet = NULL;
1040 
1041 	if (haderr) {
1042 	    if (!catch) {
1043 		/* unwind */
1044 		doneinp = 0;
1045 		resexit(osetexit);
1046 		savet = t;
1047 		reset();
1048 	    }
1049 	    haderr = 0;
1050 	    /*
1051 	     * Every error is eventually caught here or the shell dies.  It is
1052 	     * at this point that we clean up any left-over open files, by
1053 	     * closing all but a fixed number of pre-defined files.  Thus
1054 	     * routines don't have to worry about leaving files open due to
1055 	     * deeper errors... they will get closed here.
1056 	     */
1057 	    closem();
1058 	    continue;
1059 	}
1060 	if (doneinp) {
1061 	    doneinp = 0;
1062 	    break;
1063 	}
1064 	if (chkstop)
1065 	    chkstop--;
1066 	if (neednote)
1067 	    pnote();
1068 	if (intty && prompt && evalvec == 0) {
1069 	    mailchk();
1070 	    /*
1071 	     * If we are at the end of the input buffer then we are going to
1072 	     * read fresh stuff. Otherwise, we are rereading input and don't
1073 	     * need or want to prompt.
1074 	     */
1075 	    if (aret == F_SEEK && fseekp == feobp)
1076 		printprompt();
1077 	    (void) fflush(cshout);
1078 	}
1079 	if (seterr) {
1080 	    xfree((ptr_t) seterr);
1081 	    seterr = NULL;
1082 	}
1083 
1084 	/*
1085 	 * Echo not only on VERBOSE, but also with history expansion. If there
1086 	 * is a lexical error then we forego history echo.
1087 	 */
1088 	if ((lex(&paraml) && !seterr && intty) || adrof(STRverbose)) {
1089 	    prlex(csherr, &paraml);
1090 	}
1091 
1092 	/*
1093 	 * The parser may lose space if interrupted.
1094 	 */
1095 	if (setintr)
1096 	    (void) sigprocmask(SIG_BLOCK, &sigset, NULL);
1097 
1098 	/*
1099 	 * Save input text on the history list if reading in old history, or it
1100 	 * is from the terminal at the top level and not in a loop.
1101 	 *
1102 	 * PWP: entry of items in the history list while in a while loop is done
1103 	 * elsewhere...
1104 	 */
1105 	if (enterhist || (catch && intty && !whyles))
1106 	    savehist(&paraml);
1107 
1108 	/*
1109 	 * Print lexical error messages, except when sourcing history lists.
1110 	 */
1111 	if (!enterhist && seterr)
1112 	    stderror(ERR_OLD);
1113 
1114 	/*
1115 	 * If had a history command :p modifier then this is as far as we
1116 	 * should go
1117 	 */
1118 	if (justpr)
1119 	    reset();
1120 
1121 	alias(&paraml);
1122 
1123 	/*
1124 	 * Parse the words of the input into a parse tree.
1125 	 */
1126 	savet = syntax(paraml.next, &paraml, 0);
1127 	if (seterr)
1128 	    stderror(ERR_OLD);
1129 
1130 	execute(savet, (tpgrp > 0 ? tpgrp : -1), NULL, NULL);
1131 
1132 	/*
1133 	 * Made it!
1134 	 */
1135 	freelex(&paraml);
1136 	freesyn((struct command *) savet), savet = NULL;
1137     }
1138     resexit(osetexit);
1139     savet = t;
1140 }
1141 
1142 void
1143 /*ARGSUSED*/
1144 dosource(v, t)
1145     Char **v;
1146     struct command *t;
1147 
1148 {
1149     Char *f;
1150     bool    hflg = 0;
1151     Char    buf[BUFSIZ];
1152 
1153     v++;
1154     if (*v && eq(*v, STRmh)) {
1155 	if (*++v == NULL)
1156 	    stderror(ERR_NAME | ERR_HFLAG);
1157 	hflg++;
1158     }
1159     (void) Strcpy(buf, *v);
1160     f = globone(buf, G_ERROR);
1161     (void) strcpy((char *) buf, short2str(f));
1162     xfree((ptr_t) f);
1163     if (!srcfile((char *) buf, 0, hflg) && !hflg)
1164 	stderror(ERR_SYSTEM, (char *) buf, strerror(errno));
1165 }
1166 
1167 /*
1168  * Check for mail.
1169  * If we are a login shell, then we don't want to tell
1170  * about any mail file unless its been modified
1171  * after the time we started.
1172  * This prevents us from telling the user things he already
1173  * knows, since the login program insists on saying
1174  * "You have mail."
1175  */
1176 static void
1177 mailchk()
1178 {
1179     struct varent *v;
1180     Char **vp;
1181     time_t  t;
1182     int     intvl, cnt;
1183     struct stat stb;
1184     bool    new;
1185 
1186     v = adrof(STRmail);
1187     if (v == 0)
1188 	return;
1189     (void) time(&t);
1190     vp = v->vec;
1191     cnt = blklen(vp);
1192     intvl = (cnt && number(*vp)) ? (--cnt, getn(*vp++)) : MAILINTVL;
1193     if (intvl < 1)
1194 	intvl = 1;
1195     if (chktim + intvl > t)
1196 	return;
1197     for (; *vp; vp++) {
1198 	if (stat(short2str(*vp), &stb) < 0)
1199 	    continue;
1200 	new = stb.st_mtime > time0.tv_sec;
1201 	if (stb.st_size == 0 || stb.st_atime > stb.st_mtime ||
1202 	    (stb.st_atime < chktim && stb.st_mtime < chktim) ||
1203 	    (loginsh && !new))
1204 	    continue;
1205 	if (cnt == 1)
1206 	    (void) fprintf(cshout, "You have %smail.\n", new ? "new " : "");
1207 	else
1208 	    (void) fprintf(cshout, "%s in %s.\n", new ? "New mail" : "Mail",
1209 			   vis_str(*vp));
1210     }
1211     chktim = t;
1212 }
1213 
1214 /*
1215  * Extract a home directory from the password file
1216  * The argument points to a buffer where the name of the
1217  * user whose home directory is sought is currently.
1218  * We write the home directory of the user back there.
1219  */
1220 int
1221 gethdir(home)
1222     Char   *home;
1223 {
1224     Char   *h;
1225     struct passwd *pw;
1226 
1227     /*
1228      * Is it us?
1229      */
1230     if (*home == '\0') {
1231 	if ((h = value(STRhome)) != NULL) {
1232 	    (void) Strcpy(home, h);
1233 	    return 0;
1234 	}
1235 	else
1236 	    return 1;
1237     }
1238 
1239     if ((pw = getpwnam(short2str(home))) != NULL) {
1240 	(void) Strcpy(home, str2short(pw->pw_dir));
1241 	return 0;
1242     }
1243     else
1244 	return 1;
1245 }
1246 
1247 /*
1248  * When didfds is set, we do I/O from 0, 1, 2 otherwise from 15, 16, 17
1249  * We also check if the shell has already changed the decriptor to point to
1250  * 0, 1, 2 when didfds is set.
1251  */
1252 #define DESC(a) (*((int *) (a)) - (didfds && *((int *) a) >= FSHIN ? FSHIN : 0))
1253 
1254 static int
1255 readf(oreo, buf, siz)
1256     void *oreo;
1257     char *buf;
1258     int siz;
1259 {
1260     return read(DESC(oreo), buf, siz);
1261 }
1262 
1263 
1264 static int
1265 writef(oreo, buf, siz)
1266     void *oreo;
1267     const char *buf;
1268     int siz;
1269 {
1270     return write(DESC(oreo), buf, siz);
1271 }
1272 
1273 static fpos_t
1274 seekf(oreo, off, whence)
1275     void *oreo;
1276     fpos_t off;
1277     int whence;
1278 {
1279     return lseek(DESC(oreo), off, whence);
1280 }
1281 
1282 
1283 static int
1284 closef(oreo)
1285     void *oreo;
1286 {
1287     return close(DESC(oreo));
1288 }
1289 
1290 
1291 /*
1292  * Print the visible version of a string.
1293  */
1294 int
1295 vis_fputc(ch, fp)
1296     int ch;
1297     FILE *fp;
1298 {
1299     char uenc[5];	/* 4 + NULL */
1300 
1301     if (ch & QUOTE)
1302 	return fputc(ch & TRIM, fp);
1303     /*
1304      * XXX: When we are in AsciiOnly we want all characters >= 0200 to
1305      * be encoded, but currently there is no way in vis to do that.
1306      */
1307     (void) vis(uenc, ch & TRIM, VIS_NOSLASH, 0);
1308     return fputs(uenc, fp);
1309 }
1310 
1311 /*
1312  * Move the initial descriptors to their eventual
1313  * resting places, closin all other units.
1314  */
1315 void
1316 initdesc()
1317 {
1318 
1319     didfds = 0;			/* 0, 1, 2 aren't set up */
1320     (void) ioctl(SHIN = dcopy(0, FSHIN), FIOCLEX, NULL);
1321     (void) ioctl(SHOUT = dcopy(1, FSHOUT), FIOCLEX, NULL);
1322     (void) ioctl(SHERR = dcopy(2, FSHERR), FIOCLEX, NULL);
1323     (void) ioctl(OLDSTD = dcopy(SHIN, FOLDSTD), FIOCLEX, NULL);
1324     closem();
1325 }
1326 
1327 
1328 __dead void
1329 #ifdef PROF
1330 done(i)
1331 #else
1332 xexit(i)
1333 #endif
1334     int     i;
1335 {
1336     untty();
1337     _exit(i);
1338     /* NOTREACHED */
1339 }
1340 
1341 #ifndef _PATH_DEFPATH
1342 static Char **
1343 defaultpath()
1344 {
1345     char   *ptr;
1346     Char  **blk, **blkp;
1347     struct stat stb;
1348 
1349     blkp = blk = (Char **) xmalloc((size_t) sizeof(Char *) * 10);
1350 
1351 #define DIRAPPEND(a)  \
1352 	if (stat(ptr = a, &stb) == 0 && S_ISDIR(stb.st_mode)) \
1353 		*blkp++ = SAVE(ptr)
1354 
1355     DIRAPPEND(_PATH_BIN);
1356     DIRAPPEND(_PATH_USRBIN);
1357 
1358 #undef DIRAPPEND
1359 
1360 #if 0
1361     if (euid != 0 && uid != 0)
1362 	*blkp++ = Strsave(STRdot);
1363 #endif
1364 
1365     *blkp = NULL;
1366     return (blk);
1367 }
1368 #endif /* _PATH_DEFPATH */
1369 
1370 void
1371 printprompt()
1372 {
1373     Char *cp;
1374 
1375     if (!whyles) {
1376 	for (cp = value(STRprompt); *cp; cp++)
1377 	    if (*cp == HIST)
1378 		(void) fprintf(cshout, "%d", eventno + 1);
1379 	    else {
1380 		if (*cp == '\\' && cp[1] == HIST)
1381 		    cp++;
1382 		(void) vis_fputc(*cp | QUOTE, cshout);
1383 	    }
1384     }
1385     else
1386 	/*
1387 	 * Prompt for forward reading loop body content.
1388 	 */
1389 	(void) fprintf(cshout, "? ");
1390     (void) fflush(cshout);
1391 }
1392