1 /* $NetBSD: eval.c,v 1.197 2024/11/11 22:57:42 kre Exp $ */
2
3 /*-
4 * Copyright (c) 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Kenneth Almquist.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36 #ifndef lint
37 #if 0
38 static char sccsid[] = "@(#)eval.c 8.9 (Berkeley) 6/8/95";
39 #else
40 __RCSID("$NetBSD: eval.c,v 1.197 2024/11/11 22:57:42 kre Exp $");
41 #endif
42 #endif /* not lint */
43
44 #include <stdbool.h>
45 #include <stdlib.h>
46 #include <signal.h>
47 #include <stdio.h>
48 #include <string.h>
49 #include <errno.h>
50 #include <limits.h>
51 #include <unistd.h>
52 #include <sys/fcntl.h>
53 #include <sys/stat.h>
54 #include <sys/times.h>
55 #include <sys/param.h>
56 #include <sys/types.h>
57 #include <sys/wait.h>
58 #include <sys/sysctl.h>
59
60 /*
61 * Evaluate a command.
62 */
63
64 #include "shell.h"
65 #include "nodes.h"
66 #include "syntax.h"
67 #include "expand.h"
68 #include "parser.h"
69 #include "jobs.h"
70 #include "eval.h"
71 #include "builtins.h"
72 #include "options.h"
73 #include "exec.h"
74 #include "redir.h"
75 #include "input.h"
76 #include "output.h"
77 #include "trap.h"
78 #include "var.h"
79 #include "memalloc.h"
80 #include "error.h"
81 #include "show.h"
82 #include "mystring.h"
83 #include "main.h"
84 #ifndef SMALL
85 #include "nodenames.h"
86 #include "myhistedit.h"
87 #endif
88
89
90 STATIC struct skipsave s_k_i_p;
91 #define evalskip (s_k_i_p.state)
92 #define skipcount (s_k_i_p.count)
93
94 STATIC int loopnest; /* current loop nesting level */
95 STATIC int funcnest; /* depth of function calls */
96 STATIC int builtin_flags; /* evalcommand flags for builtins */
97 /*
98 * Base function nesting level inside a dot command. Set to 0 initially
99 * and to (funcnest + 1) before every dot command to enable
100 * 1) detection of being in a file sourced by a dot command and
101 * 2) counting of function nesting in that file for the implementation
102 * of the return command.
103 * The value is reset to its previous value after the dot command.
104 */
105 STATIC int dot_funcnest;
106
107
108 const char *commandname;
109 struct strlist *cmdenviron;
110 int exitstatus; /* exit status of last command */
111 int back_exitstatus; /* exit status of backquoted command */
112
113
114 STATIC void evalloop(union node *, int);
115 STATIC void evalfor(union node *, int);
116 STATIC void evalcase(union node *, int);
117 STATIC void evalsubshell(union node *, int);
118 STATIC void expredir(union node *);
119 STATIC void evalredir(union node *, int);
120 STATIC void evalpipe(union node *);
121 STATIC void evalcommand(union node *, int, struct backcmd *);
122 STATIC void prehash(union node *);
123
124 STATIC char *find_dot_file(char *);
125
126 /*
127 * Called to reset things after an exception.
128 */
129
130 #ifdef mkinit
131 INCLUDE "eval.h"
132
133 RESET {
134 reset_eval();
135 }
136
137 SHELLPROC {
138 exitstatus = 0;
139 }
140 #endif
141
142 void
reset_eval(void)143 reset_eval(void)
144 {
145 evalskip = SKIPNONE;
146 dot_funcnest = 0;
147 loopnest = 0;
148 funcnest = 0;
149 }
150
151 static int
sh_pipe(int fds[2])152 sh_pipe(int fds[2])
153 {
154 int nfd;
155
156 if (pipe(fds))
157 return -1;
158
159 if (fds[0] < 3) {
160 nfd = fcntl(fds[0], F_DUPFD, 3);
161 if (nfd != -1) {
162 close(fds[0]);
163 fds[0] = nfd;
164 }
165 }
166
167 if (fds[1] < 3) {
168 nfd = fcntl(fds[1], F_DUPFD, 3);
169 if (nfd != -1) {
170 close(fds[1]);
171 fds[1] = nfd;
172 }
173 }
174 return 0;
175 }
176
177
178 /*
179 * The eval command.
180 */
181
182 int
evalcmd(int argc,char ** argv)183 evalcmd(int argc, char **argv)
184 {
185 char *p;
186 char *concat;
187 char **ap;
188
189 if (argc > 1) {
190 p = argv[1];
191 if (argc > 2) {
192 STARTSTACKSTR(concat);
193 ap = argv + 2;
194 for (;;) {
195 while (*p)
196 STPUTC(*p++, concat);
197 if ((p = *ap++) == NULL)
198 break;
199 STPUTC(' ', concat);
200 }
201 STPUTC('\0', concat);
202 p = grabstackstr(concat);
203 }
204 evalstring(p, builtin_flags & EV_TESTED);
205 } else
206 exitstatus = 0;
207 return exitstatus;
208 }
209
210
211 /*
212 * Execute a command or commands contained in a string.
213 */
214
215 void
evalstring(const char * s,int flag)216 evalstring(const char *s, int flag)
217 {
218 union node *n;
219 struct stackmark smark;
220 int last;
221 int any;
222
223 last = flag & EV_EXIT;
224 flag &= ~EV_EXIT;
225
226 setstackmark(&smark);
227 setinputstring(s, 1, line_number);
228
229 any = 0; /* to determine if exitstatus will have been set */
230 while ((n = parsecmd(0)) != NEOF) {
231 XTRACE(DBG_EVAL, ("evalstring: "), showtree(n));
232 if (n && nflag == 0) {
233 if (last && at_eof())
234 evaltree(n, flag | EV_EXIT);
235 else
236 evaltree(n, flag);
237 any = 1;
238 if (evalskip)
239 break;
240 }
241 rststackmark(&smark);
242 }
243 popfile();
244 popstackmark(&smark);
245 if (!any)
246 exitstatus = 0;
247 if (last)
248 exraise(EXEXIT);
249 }
250
251
252
253 /*
254 * Evaluate a parse tree. The value is left in the global variable
255 * exitstatus.
256 */
257
258 void
evaltree(union node * n,int flags)259 evaltree(union node *n, int flags)
260 {
261 bool do_etest;
262 int sflags = flags & ~EV_EXIT;
263 union node *next;
264 struct stackmark smark;
265
266 do_etest = false;
267 if (n == NULL || nflag) {
268 VTRACE(DBG_EVAL, ("evaltree(%s) called\n",
269 n == NULL ? "NULL" : "-n"));
270 if (nflag == 0)
271 exitstatus = 0;
272 goto out2;
273 }
274
275 setstackmark(&smark);
276 do {
277 #ifndef SMALL
278 displayhist = 1; /* show history substitutions done with fc */
279 #endif
280 next = NULL;
281 CTRACE(DBG_EVAL, ("pid %d, evaltree(%p: %s(%d), %#x) called\n",
282 getpid(), n, NODETYPENAME(n->type), n->type, flags));
283 /*
284 if (n->type != NCMD && traps_invalid)
285 free_traps();
286 */
287 switch (n->type) {
288 case NSEMI:
289 evaltree(n->nbinary.ch1, sflags);
290 if (nflag || evalskip)
291 goto out1;
292 next = n->nbinary.ch2;
293 break;
294 case NAND:
295 evaltree(n->nbinary.ch1, EV_TESTED);
296 if (nflag || evalskip || exitstatus != 0)
297 goto out1;
298 next = n->nbinary.ch2;
299 break;
300 case NOR:
301 evaltree(n->nbinary.ch1, EV_TESTED);
302 if (nflag || evalskip || exitstatus == 0)
303 goto out1;
304 next = n->nbinary.ch2;
305 break;
306 case NREDIR:
307 if (traps_invalid)
308 free_traps();
309 evalredir(n, flags);
310 break;
311 case NSUBSHELL:
312 evalsubshell(n, flags);
313 do_etest = !(flags & EV_TESTED);
314 break;
315 case NBACKGND:
316 if (traps_invalid)
317 free_traps();
318 evalsubshell(n, flags);
319 break;
320 case NIF: {
321 if (traps_invalid)
322 free_traps();
323 evaltree(n->nif.test, EV_TESTED);
324 if (nflag || evalskip)
325 goto out1;
326 if (exitstatus == 0)
327 next = n->nif.ifpart;
328 else if (n->nif.elsepart)
329 next = n->nif.elsepart;
330 else
331 exitstatus = 0;
332 break;
333 }
334 case NWHILE:
335 case NUNTIL:
336 if (traps_invalid)
337 free_traps();
338 evalloop(n, sflags);
339 break;
340 case NFOR:
341 if (traps_invalid)
342 free_traps();
343 evalfor(n, sflags);
344 break;
345 case NCASE:
346 if (traps_invalid)
347 free_traps();
348 evalcase(n, sflags);
349 break;
350 case NDEFUN:
351 if (traps_invalid)
352 free_traps();
353 CTRACE(DBG_EVAL, ("Defining fn %s @%d%s\n",
354 n->narg.text, n->narg.lineno,
355 fnline1 ? " LINENO=1" : ""));
356 defun(n->narg.text, n->narg.next, n->narg.lineno);
357 exitstatus = 0;
358 break;
359 case NNOT:
360 evaltree(n->nnot.com, EV_TESTED);
361 exitstatus = !exitstatus;
362 break;
363 case NDNOT:
364 evaltree(n->nnot.com, EV_TESTED);
365 if (exitstatus != 0)
366 exitstatus = 1;
367 break;
368 case NPIPE:
369 if (traps_invalid)
370 free_traps();
371 evalpipe(n);
372 do_etest = !(flags & EV_TESTED);
373 break;
374 case NCMD:
375 evalcommand(n, flags, NULL);
376 do_etest = !(flags & EV_TESTED);
377 break;
378 default:
379 #ifdef NODETYPENAME
380 out1fmt("Node type = %d(%s)\n",
381 n->type, NODETYPENAME(n->type));
382 #else
383 out1fmt("Node type = %d\n", n->type);
384 #endif
385 flushout(&output);
386 break;
387 }
388 n = next;
389 rststackmark(&smark);
390 } while(n != NULL);
391 out1:
392 popstackmark(&smark);
393 out2:
394 if (pendingsigs)
395 dotrap();
396 if (eflag && exitstatus != 0 && do_etest)
397 exitshell(exitstatus);
398 if (flags & EV_EXIT)
399 exraise(EXEXIT);
400 }
401
402
403 STATIC void
evalloop(union node * n,int flags)404 evalloop(union node *n, int flags)
405 {
406 int status;
407
408 loopnest++;
409 status = 0;
410
411 CTRACE(DBG_EVAL, ("evalloop %s:", NODETYPENAME(n->type)));
412 VXTRACE(DBG_EVAL, (" "), showtree(n->nbinary.ch1));
413 VXTRACE(DBG_EVAL, ("evalloop do: "), showtree(n->nbinary.ch2));
414 VTRACE(DBG_EVAL, ("evalloop done\n"));
415 CTRACE(DBG_EVAL, ("\n"));
416
417 for (;;) {
418 evaltree(n->nbinary.ch1, EV_TESTED);
419 if (nflag)
420 break;
421 if (evalskip) {
422 skipping: if (evalskip == SKIPCONT && --skipcount <= 0) {
423 evalskip = SKIPNONE;
424 continue;
425 }
426 if (evalskip == SKIPBREAK && --skipcount <= 0)
427 evalskip = SKIPNONE;
428 if (evalskip == SKIPFUNC || evalskip == SKIPFILE)
429 status = exitstatus;
430 break;
431 }
432 if (n->type == NWHILE) {
433 if (exitstatus != 0)
434 break;
435 } else {
436 if (exitstatus == 0)
437 break;
438 }
439 evaltree(n->nbinary.ch2, flags & EV_TESTED);
440 status = exitstatus;
441 if (evalskip)
442 goto skipping;
443 }
444 loopnest--;
445 exitstatus = status;
446 }
447
448
449
450 STATIC void
evalfor(union node * n,int flags)451 evalfor(union node *n, int flags)
452 {
453 struct arglist arglist;
454 union node *argp;
455 struct strlist *sp;
456 struct stackmark smark;
457 int status;
458
459 status = nflag ? exitstatus : 0;
460
461 setstackmark(&smark);
462 arglist.lastp = &arglist.list;
463 for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
464 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
465 if (evalskip)
466 goto out;
467 }
468 *arglist.lastp = NULL;
469
470 loopnest++;
471 for (sp = arglist.list ; sp ; sp = sp->next) {
472 line_number = n->nfor.lineno;
473 if (xflag) {
474 outxstr(expandstr(ps4val(), line_number));
475 outxstr("for ");
476 outxstr(n->nfor.var);
477 outxc('=');
478 outxshstr(sp->text);
479 outxc('\n');
480 flushout(outx);
481 }
482
483 setvar(n->nfor.var, sp->text, 0);
484 evaltree(n->nfor.body, flags & EV_TESTED);
485 status = exitstatus;
486 if (nflag)
487 break;
488 if (evalskip) {
489 if (evalskip == SKIPCONT && --skipcount <= 0) {
490 evalskip = SKIPNONE;
491 continue;
492 }
493 if (evalskip == SKIPBREAK && --skipcount <= 0)
494 evalskip = SKIPNONE;
495 break;
496 }
497 }
498 loopnest--;
499 exitstatus = status;
500 out:
501 popstackmark(&smark);
502 }
503
504
505
506 STATIC void
evalcase(union node * n,int flags)507 evalcase(union node *n, int flags)
508 {
509 union node *cp, *ncp;
510 union node *patp;
511 struct arglist arglist;
512 struct stackmark smark;
513 int status = 0;
514
515 setstackmark(&smark);
516 arglist.lastp = &arglist.list;
517 line_number = n->ncase.lineno;
518 expandarg(n->ncase.expr, &arglist, EXP_TILDE);
519 for (cp = n->ncase.cases; cp && evalskip == 0; cp = cp->nclist.next) {
520 for (patp = cp->nclist.pattern; patp; patp = patp->narg.next) {
521 line_number = patp->narg.lineno;
522 if (casematch(patp, arglist.list->text)) {
523 while (cp != NULL && evalskip == 0 &&
524 nflag == 0) {
525 if (cp->type == NCLISTCONT)
526 ncp = cp->nclist.next;
527 else
528 ncp = NULL;
529 line_number = cp->nclist.lineno;
530 evaltree(cp->nclist.body, flags);
531 status = exitstatus;
532 cp = ncp;
533 }
534 goto out;
535 }
536 }
537 }
538 out:
539 exitstatus = status;
540 popstackmark(&smark);
541 }
542
543
544
545 /*
546 * Kick off a subshell to evaluate a tree.
547 */
548
549 STATIC void
evalsubshell(union node * n,int flags)550 evalsubshell(union node *n, int flags)
551 {
552 struct job *jp= NULL;
553 int backgnd = (n->type == NBACKGND);
554
555 expredir(n->nredir.redirect);
556 if (xflag && n->nredir.redirect) {
557 union node *rn;
558
559 outxstr(expandstr(ps4val(), line_number));
560 outxstr("using redirections:");
561 for (rn = n->nredir.redirect; rn; rn = rn->nfile.next)
562 (void) outredir(outx, rn, ' ');
563 outxstr(" do subshell ("/*)*/);
564 if (backgnd)
565 outxstr(/*(*/") &");
566 outxc('\n');
567 flushout(outx);
568 }
569 INTOFF;
570 if ((!backgnd && flags & EV_EXIT && !have_traps() && !anyjobs()) ||
571 forkshell(jp = makejob(n, 1), n, backgnd?FORK_BG:FORK_FG) == 0) {
572 if (backgnd)
573 flags &=~ EV_TESTED;
574 INTON;
575 redirect(n->nredir.redirect, REDIR_KEEP);
576 evaltree(n->nredir.n, flags | EV_EXIT); /* never returns */
577 } else if (backgnd) {
578 jobstarted(jp);
579 exitstatus = 0;
580 } else
581 exitstatus = waitforjob(jp);
582 INTON;
583
584 if (!backgnd && xflag && n->nredir.redirect) {
585 outxstr(expandstr(ps4val(), line_number));
586 outxstr(/*(*/") done subshell\n");
587 flushout(outx);
588 }
589 }
590
591
592
593 /*
594 * Compute the names of the files in a redirection list.
595 */
596
597 STATIC void
expredir(union node * n)598 expredir(union node *n)
599 {
600 union node *redir;
601
602 for (redir = n ; redir ; redir = redir->nfile.next) {
603 struct arglist fn;
604
605 fn.lastp = &fn.list;
606 switch (redir->type) {
607 case NFROMTO:
608 case NFROM:
609 case NTO:
610 case NCLOBBER:
611 case NAPPEND:
612 expandarg(redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
613 redir->nfile.expfname = fn.list->text;
614 break;
615 case NFROMFD:
616 case NTOFD:
617 if (redir->ndup.vname) {
618 expandarg(redir->ndup.vname, &fn, EXP_TILDE | EXP_REDIR);
619 fixredir(redir, fn.list->text, 1);
620 }
621 break;
622 case NHERE:
623 redir->nhere.text = redir->nhere.doc->narg.text;
624 break;
625 case NXHERE:
626 redir->nhere.text = expandhere(redir->nhere.doc);
627 break;
628 }
629 }
630 }
631
632 /*
633 * Perform redirections for a compound command, and then do it (and restore)
634 */
635 STATIC void
evalredir(union node * n,int flags)636 evalredir(union node *n, int flags)
637 {
638 struct jmploc jmploc;
639 struct jmploc * const savehandler = handler;
640 volatile int in_redirect = 1;
641 const char * volatile PS4 = NULL;
642
643 expredir(n->nredir.redirect);
644
645 if (xflag && n->nredir.redirect) {
646 union node *rn;
647
648 outxstr(PS4 = expandstr(ps4val(), line_number));
649 outxstr("using redirections:");
650 for (rn = n->nredir.redirect; rn != NULL; rn = rn->nfile.next)
651 (void) outredir(outx, rn, ' ');
652 outxstr(" do {\n"); /* } */
653 flushout(outx);
654 }
655
656 if (setjmp(jmploc.loc)) {
657 int e;
658
659 handler = savehandler;
660 e = exception;
661 popredir(POPREDIR_UNDO);
662 if (PS4 != NULL) {
663 outxstr(PS4);
664 /* { */ outxstr("} failed\n");
665 flushout(outx);
666 }
667 if (e == EXERROR || e == EXEXEC) {
668 if (in_redirect) {
669 exitstatus = 2;
670 return;
671 }
672 }
673 longjmp(handler->loc, 1);
674 } else {
675 INTOFF;
676 handler = &jmploc;
677 redirect(n->nredir.redirect, REDIR_PUSH | REDIR_KEEP);
678 in_redirect = 0;
679 INTON;
680 evaltree(n->nredir.n, flags);
681 }
682 INTOFF;
683 handler = savehandler;
684 popredir(POPREDIR_UNDO);
685 INTON;
686
687 if (PS4 != NULL) {
688 outxstr(PS4);
689 /* { */ outxstr("} done\n");
690 flushout(outx);
691 }
692 }
693
694
695 /*
696 * Evaluate a pipeline. All the processes in the pipeline are children
697 * of the process creating the pipeline. (This differs from some versions
698 * of the shell, which make the last process in a pipeline the parent
699 * of all the rest.)
700 */
701
702 STATIC void
evalpipe(union node * n)703 evalpipe(union node *n)
704 {
705 struct job *jp;
706 struct nodelist *lp;
707 int pipelen;
708 int prevfd;
709 int pip[2];
710
711 CTRACE(DBG_EVAL, ("evalpipe(%p) called\n", n));
712 pipelen = 0;
713 for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
714 pipelen++;
715 INTOFF;
716 jp = makejob(n, pipelen);
717 prevfd = -1;
718 for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
719 prehash(lp->n);
720 pip[1] = -1;
721 if (lp->next) {
722 if (sh_pipe(pip) < 0) {
723 if (prevfd >= 0)
724 close(prevfd);
725 error("Pipe call failed: %s", strerror(errno));
726 }
727 }
728 if (forkshell(jp, lp->n,
729 n->npipe.backgnd ? FORK_BG : FORK_FG) == 0) {
730 INTON;
731 if (prevfd > 0)
732 movefd(prevfd, 0);
733 if (pip[1] >= 0) {
734 close(pip[0]);
735 movefd(pip[1], 1);
736 }
737 evaltree(lp->n, EV_EXIT);
738 }
739 if (prevfd >= 0)
740 close(prevfd);
741 prevfd = pip[0];
742 close(pip[1]);
743 }
744 if (n->npipe.backgnd == 0) {
745 exitstatus = waitforjob(jp);
746 CTRACE(DBG_EVAL, ("evalpipe: job done exit status %d\n",
747 exitstatus));
748 } else {
749 jobstarted(jp);
750 exitstatus = 0;
751 }
752 INTON;
753 }
754
755
756
757 /*
758 * Execute a command inside back quotes. If it's a builtin command, we
759 * want to save its output in a block obtained from malloc. Otherwise
760 * we fork off a subprocess and get the output of the command via a pipe.
761 * Should be called with interrupts off.
762 */
763
764 void
evalbackcmd(union node * n,struct backcmd * result)765 evalbackcmd(union node *n, struct backcmd *result)
766 {
767 int pip[2];
768 struct job *jp;
769 struct stackmark smark; /* unnecessary (because we fork) */
770
771 result->fd = -1;
772 result->buf = NULL;
773 result->nleft = 0;
774 result->jp = NULL;
775
776 if (nflag || n == NULL)
777 goto out;
778
779 setstackmark(&smark);
780
781 #ifdef notyet
782 /*
783 * For now we disable executing builtins in the same
784 * context as the shell, because we are not keeping
785 * enough state to recover from changes that are
786 * supposed only to affect subshells. eg. echo "`cd /`"
787 */
788 if (n->type == NCMD) {
789 exitstatus = oexitstatus; /* XXX o... no longer exists */
790 evalcommand(n, EV_BACKCMD, result);
791 } else
792 #endif
793 {
794 INTOFF;
795 if (sh_pipe(pip) < 0)
796 error("Pipe call failed");
797 jp = makejob(n, 1);
798 if (forkshell(jp, n, FORK_NOJOB) == 0) {
799 FORCEINTON;
800 close(pip[0]);
801 movefd(pip[1], 1);
802 evaltree(n, EV_EXIT);
803 /* NOTREACHED */
804 }
805 close(pip[1]);
806 result->fd = pip[0];
807 result->jp = jp;
808 INTON;
809 }
810 popstackmark(&smark);
811 out:
812 CTRACE(DBG_EVAL, ("evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
813 result->fd, result->buf, result->nleft, result->jp));
814 }
815
816 const char *
syspath(void)817 syspath(void)
818 {
819 static char *sys_path = NULL;
820 static int mib[] = {CTL_USER, USER_CS_PATH};
821 static char def_path[] = "PATH=/usr/bin:/bin:/usr/sbin:/sbin";
822 size_t len;
823
824 if (sys_path == NULL) {
825 if (sysctl(mib, 2, 0, &len, 0, 0) != -1 &&
826 (sys_path = ckmalloc(len + 5)) != NULL &&
827 sysctl(mib, 2, sys_path + 5, &len, 0, 0) != -1) {
828 memcpy(sys_path, "PATH=", 5);
829 } else {
830 ckfree(sys_path);
831 /* something to keep things happy */
832 sys_path = def_path;
833 }
834 }
835 return sys_path;
836 }
837
838 static int
parse_command_args(int argc,char ** argv,int * use_syspath)839 parse_command_args(int argc, char **argv, int *use_syspath)
840 {
841 int sv_argc = argc;
842 char *cp, c;
843
844 *use_syspath = 0;
845
846 for (;;) {
847 argv++;
848 if (--argc == 0)
849 break;
850 cp = *argv;
851 if (*cp++ != '-')
852 break;
853 if (*cp == '-' && cp[1] == 0) {
854 argv++;
855 argc--;
856 break;
857 }
858 while ((c = *cp++)) {
859 switch (c) {
860 case 'p':
861 *use_syspath = 1;
862 break;
863 default:
864 /* run 'typecmd' for other options */
865 return 0;
866 }
867 }
868 }
869 return sv_argc - argc;
870 }
871
872 int vforked = 0;
873
874 /*
875 * Execute a simple command.
876 */
877
878 STATIC void
evalcommand(union node * cmd,int flgs,struct backcmd * backcmd)879 evalcommand(union node *cmd, int flgs, struct backcmd *backcmd)
880 {
881 struct stackmark smark;
882 union node *argp;
883 struct arglist arglist;
884 struct arglist varlist;
885 volatile int flags = flgs;
886 char ** volatile argv;
887 volatile int argc;
888 char **envp;
889 int varflag;
890 struct strlist *sp;
891 volatile int mode;
892 int pip[2];
893 struct cmdentry cmdentry;
894 struct job * volatile jp;
895 struct jmploc jmploc;
896 struct jmploc *volatile savehandler = NULL;
897 const char *volatile savecmdname;
898 volatile struct shparam saveparam;
899 struct localvar *volatile savelocalvars;
900 struct parsefile *volatile savetopfile;
901 volatile int e;
902 char * volatile lastarg;
903 const char * volatile path = pathval();
904 volatile int temp_path;
905 const int savefuncline = funclinebase;
906 const int savefuncabs = funclineabs;
907 volatile int cmd_flags = 0;
908
909 vforked = 0;
910 /* First expand the arguments. */
911 CTRACE(DBG_EVAL, ("evalcommand(%p, %d) called [%s]\n", cmd, flags,
912 cmd->ncmd.args ? cmd->ncmd.args->narg.text : ""));
913 setstackmark(&smark);
914 back_exitstatus = 0;
915
916 line_number = cmd->ncmd.lineno;
917
918 arglist.lastp = &arglist.list;
919 varflag = 1;
920 /* Expand arguments, ignoring the initial 'name=value' ones */
921 for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
922 if (varflag && isassignment(argp->narg.text))
923 continue;
924 varflag = 0;
925 line_number = argp->narg.lineno;
926 expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
927 }
928 *arglist.lastp = NULL;
929
930 expredir(cmd->ncmd.redirect);
931
932 /* Now do the initial 'name=value' ones we skipped above */
933 varlist.lastp = &varlist.list;
934 for (argp = cmd->ncmd.args ; argp ; argp = argp->narg.next) {
935 line_number = argp->narg.lineno;
936 if (!isassignment(argp->narg.text))
937 break;
938 /* EXP_CASE handles CTL* chars in expansions properly */
939 expandarg(argp, &varlist, EXP_VARTILDE | EXP_CASE);
940 }
941 *varlist.lastp = NULL;
942
943 argc = 0;
944 for (sp = arglist.list ; sp ; sp = sp->next)
945 argc++;
946 argv = stalloc(sizeof (char *) * (argc + 1));
947
948 for (sp = arglist.list ; sp ; sp = sp->next) {
949 VTRACE(DBG_EVAL, ("evalcommand arg: %s\n", sp->text));
950 *argv++ = sp->text;
951 }
952 *argv = NULL;
953 lastarg = NULL;
954 if (iflag && funcnest == 0 && argc > 0)
955 lastarg = argv[-1];
956 argv -= argc;
957
958 /* Print the command if xflag is set. */
959 if (xflag) {
960 char sep = 0;
961 union node *rn;
962
963 outxstr(expandstr(ps4val(), line_number));
964 for (sp = varlist.list ; sp ; sp = sp->next) {
965 char *p;
966
967 if (sep != 0)
968 outxc(sep);
969
970 /*
971 * The "var=" part should not be quoted, regardless
972 * of the value, or it would not represent an
973 * assignment, but rather a command
974 */
975 p = strchr(sp->text, '=');
976 if (p != NULL) {
977 *p = '\0'; /*XXX*/
978 outxshstr(sp->text);
979 outxc('=');
980 *p++ = '='; /*XXX*/
981 } else
982 p = sp->text;
983 outxshstr(p);
984 sep = ' ';
985 }
986 for (sp = arglist.list ; sp ; sp = sp->next) {
987 if (sep != 0)
988 outxc(sep);
989 outxshstr(sp->text);
990 sep = ' ';
991 }
992 for (rn = cmd->ncmd.redirect; rn; rn = rn->nfile.next)
993 if (outredir(outx, rn, sep))
994 sep = ' ';
995 outxc('\n');
996 flushout(outx);
997 }
998
999 /* Now locate the command. */
1000 if (argc == 0) {
1001 /*
1002 * the empty command begins as a normal builtin, and
1003 * remains that way while redirects are processed, then
1004 * will become special before we get to doing the
1005 * var assigns.
1006 */
1007 cmdentry.cmdtype = CMDBUILTIN;
1008 cmdentry.u.bltin = bltincmd;
1009 VTRACE(DBG_CMDS, ("No command name, assume \"command\"\n"));
1010 } else {
1011 static const char PATH[] = "PATH=";
1012
1013 /*
1014 * Modify the command lookup path, if a PATH= assignment
1015 * is present
1016 */
1017 for (sp = varlist.list; sp; sp = sp->next)
1018 if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0)
1019 path = sp->text + sizeof(PATH) - 1;
1020
1021 do {
1022 int argsused, use_syspath;
1023
1024 find_command(argv[0], &cmdentry, cmd_flags, path);
1025 VTRACE(DBG_CMDS, ("Command %s type %d\n", argv[0],
1026 cmdentry.cmdtype));
1027 #if 0
1028 /*
1029 * This short circuits all of the processing that
1030 * should be done (including processing the
1031 * redirects), so just don't ...
1032 *
1033 * (eventually this whole #if'd block will vanish)
1034 */
1035 if (cmdentry.cmdtype == CMDUNKNOWN) {
1036 exitstatus = 127;
1037 flushout(&errout);
1038 goto out;
1039 }
1040 #endif
1041
1042 /* implement the 'command' builtin here */
1043 if (cmdentry.cmdtype != CMDBUILTIN ||
1044 cmdentry.u.bltin != bltincmd)
1045 break;
1046 VTRACE(DBG_CMDS, ("Command \"command\"\n"));
1047 cmd_flags |= DO_NOFUNC;
1048 argsused = parse_command_args(argc, argv, &use_syspath);
1049 if (argsused == 0) {
1050 /* use 'type' builtin to display info */
1051 VTRACE(DBG_CMDS,
1052 ("Command \"command\" -> \"type\"\n"));
1053 cmdentry.u.bltin = typecmd;
1054 break;
1055 }
1056 argc -= argsused;
1057 argv += argsused;
1058 if (use_syspath)
1059 path = syspath() + 5;
1060 } while (argc != 0);
1061 if (cmdentry.cmdtype == CMDSPLBLTIN && cmd_flags & DO_NOFUNC)
1062 /* posix mandates that 'command <splbltin>' act as if
1063 <splbltin> was a normal builtin */
1064 cmdentry.cmdtype = CMDBUILTIN;
1065 }
1066
1067 /*
1068 * When traps are invalid, we permit the following:
1069 * trap
1070 * command trap
1071 * eval trap
1072 * command eval trap
1073 * eval command trap
1074 * without zapping the traps completely, in all other cases we do.
1075 * Function calls also do not zap the traps (but commands they execute
1076 * probably will) - this allows a function like
1077 * trapstate() { trap -p; }
1078 * called as save_traps=$(trapstate).
1079 *
1080 * The test here permits eval "anything" but when evalstring() comes
1081 * back here again, the "anything" will be validated.
1082 * This means we can actually do:
1083 * eval eval eval command eval eval command trap
1084 * as long as we end up with just "trap"
1085 *
1086 * We permit "command" by allowing CMDBUILTIN as well as CMDSPLBLTIN
1087 *
1088 * trapcmd() takes care of doing free_traps() if it is needed there.
1089 */
1090 if (traps_invalid &&
1091 cmdentry.cmdtype != CMDFUNCTION &&
1092 ((cmdentry.cmdtype!=CMDSPLBLTIN && cmdentry.cmdtype!=CMDBUILTIN) ||
1093 (cmdentry.u.bltin != trapcmd && cmdentry.u.bltin != evalcmd)))
1094 free_traps();
1095
1096 /* Fork off a child process if necessary. */
1097 if (cmd->ncmd.backgnd
1098 || ((cmdentry.cmdtype == CMDNORMAL || cmdentry.cmdtype == CMDUNKNOWN)
1099 && (have_traps() || (flags & EV_EXIT) == 0))
1100 #ifdef notyet /* EV_BACKCMD is never set currently */
1101 /* this will need more work if/when it gets used */
1102 || ((flags & EV_BACKCMD) != 0
1103 && (cmdentry.cmdtype != CMDBUILTIN
1104 && cmdentry.cmdtype != CMDSPLBLTIN)
1105 || cmdentry.u.bltin == dotcmd
1106 || cmdentry.u.bltin == evalcmd)
1107 #endif
1108 ) {
1109 INTOFF;
1110 jp = makejob(cmd, 1);
1111 mode = cmd->ncmd.backgnd;
1112 if (flags & EV_BACKCMD) {
1113 mode = FORK_NOJOB;
1114 if (sh_pipe(pip) < 0)
1115 error("Pipe call failed");
1116 }
1117 #ifdef DO_SHAREDVFORK
1118 /* It is essential that if DO_SHAREDVFORK is defined that the
1119 * child's address space is actually shared with the parent as
1120 * we rely on this.
1121 */
1122 if (usefork == 0 && cmdentry.cmdtype == CMDNORMAL &&
1123 (!cmd->ncmd.backgnd || cmd->ncmd.redirect == NULL)) {
1124 pid_t pid;
1125 int serrno;
1126
1127 savelocalvars = localvars;
1128 localvars = NULL;
1129 vforked = 1;
1130 VFORK_BLOCK
1131 switch (pid = vfork()) {
1132 case -1:
1133 serrno = errno;
1134 VTRACE(DBG_EVAL, ("vfork() failed, errno=%d\n",
1135 serrno));
1136 INTON;
1137 error("Cannot vfork (%s)", strerror(serrno));
1138 break;
1139 case 0:
1140 /* Make sure that exceptions only unwind to
1141 * after the vfork(2)
1142 */
1143 SHELL_FORKED();
1144 if (setjmp(jmploc.loc)) {
1145 VTRACE(DBG_EVAL|DBG_ERRS|
1146 DBG_PROCS|DBG_CMDS|DBG_TRAP,
1147 ("vfork child exit exception:%d "
1148 "exitstatus:%d exerrno:%d\n",
1149 exception, exitstatus, exerrno));
1150
1151 if (exception == EXSHELLPROC) {
1152 /*
1153 * We can't progress with the
1154 * vfork, so, set vforked = 2
1155 * so the parent knows,
1156 * and _exit();
1157 */
1158 vforked = 2;
1159 _exit(0);
1160 } else {
1161 _exit(exception == EXEXIT ?
1162 exitstatus : exerrno);
1163 }
1164 }
1165 savehandler = handler;
1166 handler = &jmploc;
1167 listmklocal(varlist.list,
1168 VDOEXPORT | VEXPORT | VNOFUNC);
1169 forkchild(jp, cmd, mode, vforked);
1170 break;
1171 default:
1172 VFORK_UNDO();
1173 /* restore from vfork(2) */
1174 CTRACE(DBG_PROCS|DBG_CMDS,
1175 ("parent after vfork - vforked=%d\n",
1176 vforked));
1177 handler = savehandler;
1178 poplocalvars();
1179 localvars = savelocalvars;
1180 if (vforked == 2) {
1181 vforked = 0;
1182
1183 (void)waitpid(pid, NULL, 0);
1184 /*
1185 * We need to progress in a
1186 * normal fork fashion
1187 */
1188 goto normal_fork;
1189 }
1190 /*
1191 * Here the child has left home,
1192 * getting on with its life, so
1193 * so must we...
1194 */
1195 vforked = 0;
1196 forkparent(jp, cmd, mode, pid);
1197 goto parent;
1198 }
1199 VFORK_END
1200 } else {
1201 normal_fork:
1202 #endif
1203 if (forkshell(jp, cmd, mode) != 0)
1204 goto parent; /* at end of routine */
1205 CTRACE(DBG_PROCS|DBG_CMDS, ("Child sets EV_EXIT\n"));
1206 flags |= EV_EXIT;
1207 FORCEINTON;
1208 #ifdef DO_SHAREDVFORK
1209 }
1210 #endif
1211 if (flags & EV_BACKCMD) {
1212 if (!vforked) {
1213 FORCEINTON;
1214 }
1215 close(pip[0]);
1216 movefd(pip[1], 1);
1217 }
1218 flags |= EV_EXIT;
1219 }
1220
1221 /* This is the child process if a fork occurred. */
1222 /* Execute the command. */
1223 switch (cmdentry.cmdtype) {
1224 volatile int saved;
1225 struct funcdef * volatile savefunc;
1226 const char * volatile savectx;
1227
1228 case CMDFUNCTION:
1229 VXTRACE(DBG_EVAL, ("Shell function%s: ",vforked?" VF":""),
1230 trargs(argv));
1231 redirect(cmd->ncmd.redirect, REDIR_KEEP | (saved =
1232 !(flags & EV_EXIT) || have_traps() ? REDIR_PUSH : 0));
1233 saveparam = shellparam;
1234 shellparam.malloc = 0;
1235 shellparam.reset = 1;
1236 shellparam.nparam = argc - 1;
1237 shellparam.p = argv + 1;
1238 shellparam.optnext = NULL;
1239 INTOFF;
1240 savelocalvars = localvars;
1241 savectx = currentcontext;
1242 localvars = NULL;
1243 reffunc(savefunc = cmdentry.u.func);
1244 INTON;
1245 if (setjmp(jmploc.loc)) {
1246 if (exception == EXSHELLPROC) {
1247 freeparam((volatile struct shparam *)
1248 &saveparam);
1249 } else {
1250 freeparam(&shellparam);
1251 shellparam = saveparam;
1252 }
1253 if (saved)
1254 popredir(POPREDIR_UNDO);
1255 unreffunc(savefunc);
1256 poplocalvars();
1257 localvars = savelocalvars;
1258 funclinebase = savefuncline;
1259 funclineabs = savefuncabs;
1260 currentcontext = savectx;
1261 handler = savehandler;
1262 longjmp(handler->loc, 1);
1263 }
1264 savehandler = handler;
1265 handler = &jmploc;
1266 if (cmdentry.u.func) {
1267 if (cmdentry.lno_frel)
1268 funclinebase = cmdentry.lineno - 1;
1269 else
1270 funclinebase = 0;
1271 funclineabs = cmdentry.lineno;
1272 currentcontext = argv[0];
1273
1274 VTRACE(DBG_EVAL,
1275 ("function: node: %d '%s' # %d%s; funclinebase=%d\n",
1276 getfuncnode(cmdentry.u.func)->type,
1277 NODETYPENAME(getfuncnode(cmdentry.u.func)->type),
1278 cmdentry.lineno, cmdentry.lno_frel?" (=1)":"",
1279 funclinebase));
1280 }
1281 listmklocal(varlist.list, VDOEXPORT | VEXPORT);
1282 /* stop shell blowing its stack */
1283 if (++funcnest > 1000)
1284 error("too many nested function calls");
1285 evaltree(getfuncnode(cmdentry.u.func),
1286 flags & (EV_TESTED|EV_EXIT));
1287 funcnest--;
1288 INTOFF;
1289 unreffunc(cmdentry.u.func);
1290 poplocalvars();
1291 localvars = savelocalvars;
1292 funclinebase = savefuncline;
1293 funclineabs = savefuncabs;
1294 currentcontext = savectx;
1295 freeparam(&shellparam);
1296 shellparam = saveparam;
1297 handler = savehandler;
1298 if (saved)
1299 popredir(POPREDIR_UNDO);
1300 INTON;
1301 if (evalskip == SKIPFUNC) {
1302 evalskip = SKIPNONE;
1303 skipcount = 0;
1304 }
1305 if (flags & EV_EXIT)
1306 exitshell(exitstatus);
1307 break;
1308
1309 case CMDSPLBLTIN:
1310 VTRACE(DBG_EVAL, ("special "));
1311 case CMDBUILTIN:
1312 VXTRACE(DBG_EVAL, ("builtin command [%d]%s: ", argc,
1313 vforked ? " VF" : ""), trargs(argv));
1314
1315 if (cmdentry.u.bltin == execcmd) {
1316 char **ap;
1317
1318 /*
1319 * Work out how we should process redirections
1320 * on the "exec" command. We need REDIR_KEEP
1321 * if we must not set close-on-exec, and REDIR_PUSH
1322 * if we need to be able to undo them (in the
1323 * exec command, only on some kind of error).
1324 *
1325 * Skip "exec" (argv[0]) then examine args.
1326 *
1327 * This must be done manually, as nextopt()
1328 * hasn't been init'd for this command yet.
1329 * And it won't be until after redirections are done.
1330 *
1331 * "exec" currently takes no options (except "--"),
1332 * but might one day, and this needs to keep working,
1333 * so do it, kind of, properly.
1334 *
1335 * Note in the common cases argv[1] will be NULL
1336 * (for exec just setting up redirectons) or will
1337 * not start with a '-' ("exec cmd") so normally
1338 * this loop will either never start or will break
1339 * at the first test of the first iteration.
1340 */
1341 for (ap = argv + 1; *ap != NULL; ap++) {
1342
1343 if (ap[0][0] != '-')
1344 break;
1345
1346 if (ap[0][1] == '\0') /* "exec -" */
1347 break; /* or continue ?? */
1348
1349 if (ap[0][1] == '-' && ap[0][2] == '\0') {
1350 ap++;
1351 break;
1352 }
1353
1354 #if defined(DUMMY_EXAMPLE_CODE) && 0
1355 /*
1356 * if options are added to "exec" then
1357 * any which take an arg (like the common
1358 * in other shells "-a cmdname") need to
1359 * be recognised here, lest "cmdname" be
1360 * thought to be the cmd to exec
1361 */
1362
1363 for (char *op = ap[0] + 1; *op; op++) {
1364 switch (*op) {
1365 case 'a':
1366 case any others similar:
1367 /* options needing an optarg */
1368 if (op[1] == '\0' && ap[1])
1369 ap++;
1370 break;
1371
1372 default:
1373 /* options with no optarg */
1374 continue;
1375 }
1376 break;
1377 }
1378 #endif /* DUMMY EXAMPLE CODE */
1379 }
1380
1381 if (*ap != NULL)
1382 mode = REDIR_KEEP; /* exec cmd <... */
1383 else
1384 mode = 0; /* exec < .... */
1385
1386 /*
1387 * always save old fd setup in case of error()
1388 * execcmd() will undo this if no error occurs
1389 * (that is, in the case the shell has not vanished)
1390 */
1391 mode |= REDIR_PUSH;
1392 } else /* any builtin execpt "exec" */
1393 mode = REDIR_PUSH | REDIR_KEEP;
1394
1395 if (flags == EV_BACKCMD) {
1396 memout.nleft = 0;
1397 memout.nextc = memout.buf;
1398 memout.bufsize = 64;
1399 mode |= REDIR_BACKQ;
1400 }
1401
1402 e = -1;
1403 savecmdname = commandname;
1404 savetopfile = getcurrentfile();
1405 savehandler = handler;
1406 temp_path = 0;
1407
1408 if (!setjmp(jmploc.loc)) {
1409 handler = &jmploc;
1410
1411 /*
1412 * We need to ensure the command hash table isn't
1413 * corrupted by temporary PATH assignments.
1414 * However we must ensure the 'local' command works!
1415 */
1416 if (path != pathval() && (cmdentry.u.bltin == hashcmd ||
1417 cmdentry.u.bltin == typecmd)) {
1418 savelocalvars = localvars;
1419 localvars = 0;
1420 temp_path = 1;
1421 mklocal(path - 5 /* PATH= */, 0);
1422 }
1423 redirect(cmd->ncmd.redirect, mode);
1424
1425 /*
1426 * the empty command is regarded as a normal
1427 * builtin for the purposes of redirects, but
1428 * is a special builtin for var assigns.
1429 * (unless we are the "command" command.)
1430 */
1431 if (argc == 0 && !(cmd_flags & DO_NOFUNC))
1432 cmdentry.cmdtype = CMDSPLBLTIN;
1433
1434 /* exec is a special builtin, but needs this list... */
1435 cmdenviron = varlist.list;
1436 /* we must check 'readonly' flag for all builtins */
1437 listsetvar(varlist.list,
1438 cmdentry.cmdtype == CMDSPLBLTIN ? 0 : VNOSET);
1439 commandname = argv[0];
1440 /* initialize nextopt */
1441 argptr = argv + 1;
1442 optptr = NULL;
1443 /* and getopt */
1444 optreset = 1;
1445 optind = 1;
1446 builtin_flags = flags;
1447 clr_err(out1); /* discard previous I/O errors */
1448 exitstatus = cmdentry.u.bltin(argc, argv);
1449 } else {
1450 e = exception;
1451 if (e == EXINT)
1452 exitstatus = SIGINT + 128;
1453 else if (e == EXEXEC)
1454 exitstatus = exerrno;
1455 else if (e != EXEXIT)
1456 exitstatus = 2;
1457 }
1458 handler = savehandler;
1459 flushall();
1460 out1 = &output;
1461 out2 = &errout;
1462 freestdout();
1463 if (temp_path) {
1464 poplocalvars();
1465 localvars = savelocalvars;
1466 }
1467 cmdenviron = NULL;
1468 if (e != EXSHELLPROC) {
1469 commandname = savecmdname;
1470 if (flags & EV_EXIT)
1471 exitshell(exitstatus);
1472 }
1473 if (e != -1) {
1474 if ((e != EXERROR && e != EXEXEC)
1475 || cmdentry.cmdtype == CMDSPLBLTIN)
1476 exraise(e);
1477 popfilesupto(savetopfile);
1478 FORCEINTON;
1479 }
1480
1481 if (cmdentry.u.bltin != execcmd)
1482 popredir(POPREDIR_UNDO);
1483
1484 if (flags == EV_BACKCMD) {
1485 backcmd->buf = memout.buf;
1486 backcmd->nleft = memout.nextc - memout.buf;
1487 memout.buf = NULL;
1488 }
1489 break;
1490
1491 default:
1492 VXTRACE(DBG_EVAL, ("normal command%s: ", vforked?" VF":""),
1493 trargs(argv));
1494 redirect(cmd->ncmd.redirect,
1495 (vforked ? REDIR_VFORK : 0) | REDIR_KEEP);
1496 if (!vforked)
1497 for (sp = varlist.list ; sp ; sp = sp->next)
1498 setvareq(sp->text, VDOEXPORT|VEXPORT|VSTACK);
1499 envp = environment();
1500 shellexec(argv, envp, path, cmdentry.u.index, vforked);
1501 break;
1502 }
1503 goto out;
1504
1505 parent: /* parent process gets here (if we forked) */
1506
1507 exitstatus = 0; /* if not altered just below */
1508 if (mode == FORK_FG) { /* argument to fork */
1509 exitstatus = waitforjob(jp);
1510 } else if (mode == FORK_NOJOB) {
1511 backcmd->fd = pip[0];
1512 close(pip[1]);
1513 backcmd->jp = jp;
1514 } else
1515 jobstarted(jp);
1516
1517 FORCEINTON;
1518
1519 out:
1520 if (lastarg)
1521 /* implement $_ for whatever use that really is */
1522 (void) setvarsafe("_", lastarg, VNOERROR);
1523 popstackmark(&smark);
1524 }
1525
1526
1527 /*
1528 * Search for a command. This is called before we fork so that the
1529 * location of the command will be available in the parent as well as
1530 * the child. The check for "goodname" is an overly conservative
1531 * check that the name will not be subject to expansion.
1532 */
1533
1534 STATIC void
prehash(union node * n)1535 prehash(union node *n)
1536 {
1537 struct cmdentry entry;
1538
1539 if (n && n->type == NCMD && n->ncmd.args)
1540 if (goodname(n->ncmd.args->narg.text))
1541 find_command(n->ncmd.args->narg.text, &entry, 0,
1542 pathval());
1543 }
1544
1545 int
in_function(void)1546 in_function(void)
1547 {
1548 return funcnest;
1549 }
1550
1551 enum skipstate
current_skipstate(void)1552 current_skipstate(void)
1553 {
1554 return evalskip;
1555 }
1556
1557 void
save_skipstate(struct skipsave * p)1558 save_skipstate(struct skipsave *p)
1559 {
1560 *p = s_k_i_p;
1561 }
1562
1563 void
restore_skipstate(const struct skipsave * p)1564 restore_skipstate(const struct skipsave *p)
1565 {
1566 s_k_i_p = *p;
1567 }
1568
1569 void
stop_skipping(void)1570 stop_skipping(void)
1571 {
1572 evalskip = SKIPNONE;
1573 skipcount = 0;
1574 }
1575
1576 /*
1577 * Builtin commands. Builtin commands whose functions are closely
1578 * tied to evaluation are implemented here.
1579 */
1580
1581 /*
1582 * No command given.
1583 */
1584
1585 int
bltincmd(int argc,char ** argv)1586 bltincmd(int argc, char **argv)
1587 {
1588 /*
1589 * Preserve exitstatus of a previous possible redirection
1590 * as POSIX mandates
1591 */
1592 return back_exitstatus;
1593 }
1594
1595
1596 /*
1597 * Handle break and continue commands. Break, continue, and return are
1598 * all handled by setting the evalskip flag. The evaluation routines
1599 * above all check this flag, and if it is set they start skipping
1600 * commands rather than executing them. The variable skipcount is
1601 * the number of loops to break/continue, or the number of function
1602 * levels to return. (The latter is always 1.) It should probably
1603 * be an error to break out of more loops than exist, but it isn't
1604 * in the standard shell so we don't make it one here.
1605 */
1606
1607 int
breakcmd(int argc,char ** argv)1608 breakcmd(int argc, char **argv)
1609 {
1610 int n = argc > 1 ? number(argv[1]) : 1;
1611
1612 if (n <= 0)
1613 error("invalid count: %d", n);
1614 if (n > loopnest)
1615 n = loopnest;
1616 if (n > 0) {
1617 evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
1618 skipcount = n;
1619 }
1620 return 0;
1621 }
1622
1623 int
dotcmd(int argc,char ** argv)1624 dotcmd(int argc, char **argv)
1625 {
1626 exitstatus = 0;
1627
1628 (void) nextopt(NULL); /* ignore a leading "--" */
1629
1630 if (*argptr != NULL) { /* That's what SVR2 does */
1631 char *fullname;
1632 /*
1633 * dot_funcnest needs to be 0 when not in a dotcmd, so it
1634 * cannot be restored with (funcnest + 1).
1635 */
1636 int dot_funcnest_old;
1637 struct stackmark smark;
1638
1639 setstackmark(&smark);
1640 fullname = find_dot_file(*argptr);
1641 setinputfile(fullname, 1);
1642 commandname = fullname;
1643 dot_funcnest_old = dot_funcnest;
1644 dot_funcnest = funcnest + 1;
1645 cmdloop(0);
1646 dot_funcnest = dot_funcnest_old;
1647 popfile();
1648 popstackmark(&smark);
1649 }
1650 return exitstatus;
1651 }
1652
1653 /*
1654 * allow dotfile function nesting to be manipulated
1655 * (for read_profile). This allows profile files to
1656 * be treated as if they were used as '.' commands,
1657 * (approximately) and in particular, for "return" to work.
1658 */
1659 int
set_dot_funcnest(int new)1660 set_dot_funcnest(int new)
1661 {
1662 int rv = dot_funcnest;
1663
1664 if (new >= 0)
1665 dot_funcnest = new;
1666
1667 return rv;
1668 }
1669
1670 /*
1671 * Take commands from a file. To be compatible we should do a path
1672 * search for the file, which is necessary to find sub-commands.
1673 */
1674
1675 STATIC char *
find_dot_file(char * basename)1676 find_dot_file(char *basename)
1677 {
1678 char *fullname;
1679 const char *path = pathval();
1680 struct stat statb;
1681
1682 /* don't try this for absolute or relative paths */
1683 if (strchr(basename, '/')) {
1684 if (stat(basename, &statb) == 0) {
1685 if (S_ISDIR(statb.st_mode))
1686 error("%s: is a directory", basename);
1687 if (S_ISBLK(statb.st_mode))
1688 error("%s: is a block device", basename);
1689 return basename;
1690 }
1691 } else while ((fullname = padvance(&path, basename, 1)) != NULL) {
1692 if ((stat(fullname, &statb) == 0)) {
1693 /* weird format is to ease future code... */
1694 if (S_ISDIR(statb.st_mode) || S_ISBLK(statb.st_mode))
1695 ;
1696 #if notyet
1697 else if (unreadable()) {
1698 /*
1699 * testing this via st_mode is ugly to get
1700 * correct (and would ignore ACLs).
1701 * better way is just to open the file.
1702 * But doing that here would (currently)
1703 * mean opening the file twice, which
1704 * might not be safe. So, defer this
1705 * test until code is restructures so
1706 * we can return a fd. Then we also
1707 * get to fix the mem leak just below...
1708 */
1709 }
1710 #endif
1711 else {
1712 /*
1713 * Don't bother freeing here, since
1714 * it will be freed by the caller.
1715 * XXX no it won't - a bug for later.
1716 */
1717 return fullname;
1718 }
1719 }
1720 stunalloc(fullname);
1721 }
1722
1723 /* not found in the PATH */
1724 error("%s: not found", basename);
1725 /* NOTREACHED */
1726 }
1727
1728
1729
1730 /*
1731 * The return command.
1732 *
1733 * Quoth the POSIX standard:
1734 * The return utility shall cause the shell to stop executing the current
1735 * function or dot script. If the shell is not currently executing
1736 * a function or dot script, the results are unspecified.
1737 *
1738 * As for the unspecified part, there seems to be no de-facto standard: bash
1739 * ignores the return with a warning, zsh ignores the return in interactive
1740 * mode but seems to liken it to exit in a script. (checked May 2014)
1741 *
1742 * We choose to silently ignore the return. Older versions of this shell
1743 * set evalskip to SKIPFILE causing the shell to (indirectly) exit. This
1744 * had at least the problem of circumventing the check for stopped jobs,
1745 * which would occur for exit or ^D.
1746 */
1747
1748 int
returncmd(int argc,char ** argv)1749 returncmd(int argc, char **argv)
1750 {
1751 int ret = argc > 1 ? number(argv[1]) : exitstatus;
1752
1753 if ((dot_funcnest == 0 && funcnest)
1754 || (dot_funcnest > 0 && funcnest - (dot_funcnest - 1) > 0)) {
1755 evalskip = SKIPFUNC;
1756 skipcount = 1;
1757 } else if (dot_funcnest > 0) {
1758 evalskip = SKIPFILE;
1759 skipcount = 1;
1760 } else {
1761 /* XXX: should a warning be issued? */
1762 ret = 0;
1763 }
1764
1765 return ret;
1766 }
1767
1768
1769 int
falsecmd(int argc,char ** argv)1770 falsecmd(int argc, char **argv)
1771 {
1772 return 1;
1773 }
1774
1775
1776 int
truecmd(int argc,char ** argv)1777 truecmd(int argc, char **argv)
1778 {
1779 return 0;
1780 }
1781
1782
1783 int
execcmd(int argc,char ** argv)1784 execcmd(int argc, char **argv)
1785 {
1786 /*
1787 * BEWARE: if any options are added here, they must
1788 * also be added in evalcommand(), look for "DUMMY_EXAMPLE_CODE"
1789 * for example code for there. Here the options would be
1790 * processed completely normally.
1791 */
1792 (void) nextopt(""); /* ignore a leading "--" */
1793
1794 if (*argptr) {
1795 struct strlist *sp;
1796
1797 iflag = 0; /* exit on error */
1798 mflag = 0;
1799 optschanged();
1800 for (sp = cmdenviron; sp; sp = sp->next)
1801 setvareq(sp->text, VDOEXPORT|VEXPORT|VSTACK);
1802 shellexec(argptr, environment(), pathval(), 0, 0);
1803 /* NOTREACHED */
1804 }
1805 popredir(POPREDIR_PERMANENT); /* make any redirections permanent */
1806 return 0;
1807 }
1808
1809 static int
conv_time(clock_t ticks,char * seconds,size_t l)1810 conv_time(clock_t ticks, char *seconds, size_t l)
1811 {
1812 static clock_t tpm = 0;
1813 clock_t mins;
1814 int i;
1815
1816 if (!tpm)
1817 tpm = sysconf(_SC_CLK_TCK) * 60;
1818
1819 mins = ticks / tpm;
1820 snprintf(seconds, l, "%.4f", (ticks - mins * tpm) * 60.0 / tpm );
1821
1822 if (seconds[0] == '6' && seconds[1] == '0') {
1823 /* 59.99995 got rounded up... */
1824 mins++;
1825 strlcpy(seconds, "0.0", l);
1826 return mins;
1827 }
1828
1829 /* suppress trailing zeros */
1830 i = strlen(seconds) - 1;
1831 for (; seconds[i] == '0' && seconds[i - 1] != '.'; i--)
1832 seconds[i] = 0;
1833 return mins;
1834 }
1835
1836 int
timescmd(int argc,char ** argv)1837 timescmd(int argc, char **argv)
1838 {
1839 struct tms tms;
1840 int u, s, cu, cs;
1841 char us[8], ss[8], cus[8], css[8];
1842
1843 nextopt("");
1844
1845 times(&tms);
1846
1847 u = conv_time(tms.tms_utime, us, sizeof(us));
1848 s = conv_time(tms.tms_stime, ss, sizeof(ss));
1849 cu = conv_time(tms.tms_cutime, cus, sizeof(cus));
1850 cs = conv_time(tms.tms_cstime, css, sizeof(css));
1851
1852 outfmt(out1, "%dm%ss %dm%ss\n%dm%ss %dm%ss\n",
1853 u, us, s, ss, cu, cus, cs, css);
1854
1855 return 0;
1856 }
1857