1 /* $NetBSD: main.c,v 1.90 2023/04/07 10:34:13 kre Exp $ */
2
3 /*-
4 * Copyright (c) 1991, 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 __COPYRIGHT("@(#) Copyright (c) 1991, 1993\
38 The Regents of the University of California. All rights reserved.");
39 #endif /* not lint */
40
41 #ifndef lint
42 #if 0
43 static char sccsid[] = "@(#)main.c 8.7 (Berkeley) 7/19/95";
44 #else
45 __RCSID("$NetBSD: main.c,v 1.90 2023/04/07 10:34:13 kre Exp $");
46 #endif
47 #endif /* not lint */
48
49 #include <errno.h>
50 #include <stdio.h>
51 #include <signal.h>
52 #include <sys/stat.h>
53 #include <unistd.h>
54 #include <stdbool.h>
55 #include <stdlib.h>
56 #include <locale.h>
57 #include <fcntl.h>
58
59
60 #include "shell.h"
61 #include "main.h"
62 #include "mail.h"
63 #include "options.h"
64 #include "builtins.h"
65 #include "output.h"
66 #include "parser.h"
67 #include "nodes.h"
68 #include "expand.h"
69 #include "eval.h"
70 #include "jobs.h"
71 #include "input.h"
72 #include "trap.h"
73 #include "var.h"
74 #include "show.h"
75 #include "memalloc.h"
76 #include "error.h"
77 #include "init.h"
78 #include "mystring.h"
79 #include "exec.h"
80 #include "cd.h"
81 #include "redir.h"
82
83 #define PROFILE 0
84
85 int rootpid;
86 int rootshell;
87 struct jmploc main_handler;
88 int max_user_fd;
89 long user_fd_limit;
90 bool privileged;
91 #if PROFILE
92 short profile_buf[16384];
93 extern int etext();
94 #endif
95
96 STATIC void read_profile(const char *);
97
98 /*
99 * Main routine. We initialize things, parse the arguments, execute
100 * profiles if we're a login shell, and then call cmdloop to execute
101 * commands. The setjmp call sets up the location to jump to when an
102 * exception occurs. When an exception occurs the variable "state"
103 * is used to figure out how far we had gotten.
104 */
105
106 int
main(int argc,char ** argv)107 main(int argc, char **argv)
108 {
109 struct stackmark smark;
110 volatile int state;
111 char *shinit;
112 uid_t uid;
113 gid_t gid;
114 sigset_t mask;
115 bool waspriv;
116
117 /*
118 * If we happen to be invoked with SIGCHLD ignored, we cannot
119 * successfully do almost anything. Perhaps we should remember
120 * its state and pass it on ignored to children if it was ignored
121 * on entry, but that seems like just leaving the shit on the
122 * footpath for someone else to fall into...
123 */
124 (void)signal(SIGCHLD, SIG_DFL);
125 /*
126 * Similarly, SIGCHLD must not be blocked
127 */
128 sigemptyset(&mask);
129 sigaddset(&mask, SIGCHLD);
130 sigprocmask(SIG_UNBLOCK, &mask, NULL);
131
132 uid = getuid();
133 gid = getgid();
134
135 waspriv = privileged = (uid != geteuid()) || (gid != getegid());
136
137 max_user_fd = fcntl(0, F_MAXFD);
138 if (max_user_fd < 2)
139 max_user_fd = 2;
140 user_fd_limit = sysconf(_SC_OPEN_MAX);
141
142 setlocale(LC_ALL, "");
143
144 posix = getenv("POSIXLY_CORRECT") != NULL;
145 #if PROFILE
146 monitor(4, etext, profile_buf, sizeof profile_buf, 50);
147 #endif
148 state = 0;
149 if (setjmp(main_handler.loc)) {
150 /*
151 * When a shell procedure is executed, we raise the
152 * exception EXSHELLPROC to clean up before executing
153 * the shell procedure.
154 */
155 switch (exception) {
156 case EXSHELLPROC:
157 rootpid = getpid();
158 rootshell = 1;
159 minusc = NULL;
160 state = 3;
161 break;
162
163 case EXEXEC:
164 exitstatus = exerrno;
165 break;
166
167 case EXERROR:
168 exitstatus = 2;
169 break;
170
171 default:
172 break;
173 }
174
175 if (exception != EXSHELLPROC) {
176 if (state == 0 || iflag == 0 || ! rootshell ||
177 exception == EXEXIT)
178 exitshell(exitstatus);
179 }
180 reset();
181 if (exception == EXINT) {
182 out2c('\n');
183 flushout(&errout);
184 }
185 popstackmark(&smark);
186 FORCEINTON; /* enable interrupts */
187 if (state == 1)
188 goto state1;
189 else if (state == 2)
190 goto state2;
191 else if (state == 3)
192 goto state3;
193 else
194 goto state4;
195 }
196 handler = &main_handler;
197 #ifdef DEBUG
198 #if DEBUG >= 2
199 debug = 1; /* this may be reset by procargs() later */
200 #endif
201 opentrace();
202 if (privileged)
203 trputs("Privileged ");
204 trputs("Shell args: "); trargs(argv);
205 #if DEBUG >= 3
206 set_debug(((DEBUG)==3 ? "_@" : "++"), 1);
207 #endif
208 #endif
209 rootpid = getpid();
210 rootshell = 1;
211 init();
212 initpwd();
213 setstackmark(&smark);
214 procargs(argc, argv);
215 setvar_invocation(argc, argv);
216
217 #if 0 /* This now happens (indirectly) in the procargs() just above */
218 /*
219 * Limit bogus system(3) or popen(3) calls in setuid binaries,
220 * by requiring the -p flag
221 */
222 if (!pflag && (uid != geteuid() || gid != getegid())) {
223 setuid(uid);
224 setgid(gid);
225 /* PS1 might need to be changed accordingly. */
226 choose_ps1();
227 }
228 #else /* except for this one little bit */
229 if (waspriv && !privileged)
230 choose_ps1();
231 #endif
232
233 if (loginsh) {
234 state = 1;
235 read_profile("/etc/profile");
236 state1:
237 state = 2;
238 if (!privileged) {
239 char *profile;
240 const char *home;
241
242 home = lookupvar("HOME");
243 if (home == NULL)
244 home = nullstr;
245 profile = ststrcat(NULL, home, "/.profile", STSTRC_END);
246 read_profile(profile);
247 stunalloc(profile);
248 }
249 #if 0 /* FreeBSD does (effectively) ...*/
250 else
251 read_profile("/etc/suid_profile");
252 #endif
253 }
254 state2:
255 state = 3;
256 if ((iflag || !posix) && !privileged) {
257 struct stackmark env_smark;
258
259 setstackmark(&env_smark);
260 if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') {
261 state = 3;
262 read_profile(expandenv(shinit));
263 }
264 popstackmark(&env_smark);
265 }
266 state3:
267 state = 4;
268 line_number = 1; /* undo anything from profile files */
269
270 if (sflag == 0 || minusc) {
271 static int sigs[] = {
272 SIGINT, SIGQUIT, SIGHUP,
273 #ifdef SIGTSTP
274 SIGTSTP,
275 #endif
276 SIGPIPE
277 };
278 #define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0]))
279 size_t i;
280
281 for (i = 0; i < SIGSSIZE; i++)
282 setsignal(sigs[i], 0);
283 }
284
285 rststackmark(&smark); /* this one is never popped */
286
287 if (minusc)
288 evalstring(minusc, sflag ? 0 : EV_EXIT);
289
290 if (sflag || minusc == NULL) {
291 state4: /* XXX ??? - why isn't this before the "if" statement */
292 cmdloop(1);
293 if (iflag) {
294 out2str("\n");
295 flushout(&errout);
296 }
297 }
298 #if PROFILE
299 monitor(0);
300 #endif
301 line_number = plinno;
302 exitshell(exitstatus);
303 /* NOTREACHED */
304 }
305
306
307 /*
308 * Read and execute commands. "Top" is nonzero for the top level command
309 * loop; it turns on prompting if the shell is interactive.
310 */
311
312 void
cmdloop(int top)313 cmdloop(int top)
314 {
315 union node *n;
316 struct stackmark smark;
317 int inter;
318 int numeof = 0;
319 enum skipstate skip;
320
321 CTRACE(DBG_ALWAYS, ("cmdloop(%d) called\n", top));
322 setstackmark(&smark);
323 for (;;) {
324 if (pendingsigs)
325 dotrap();
326 inter = 0;
327 if (iflag == 1 && top) {
328 inter = 1;
329 showjobs(out2, SHOW_CHANGED);
330 chkmail(0);
331 flushout(&errout);
332 nflag = 0;
333 }
334 n = parsecmd(inter);
335 VXTRACE(DBG_PARSE|DBG_EVAL|DBG_CMDS,("cmdloop: "),showtree(n));
336 if (n == NEOF) {
337 if (!top || numeof >= 50)
338 break;
339 if (nflag)
340 break;
341 if (!stoppedjobs()) {
342 if (!iflag || !Iflag)
343 break;
344 out2str("\nUse \"exit\" to leave shell.\n");
345 }
346 numeof++;
347 } else if (n != NULL && nflag == 0) {
348 job_warning = (job_warning == 2) ? 1 : 0;
349 numeof = 0;
350 evaltree(n, 0);
351 }
352 rststackmark(&smark);
353
354 /*
355 * Any SKIP* can occur here! SKIP(FUNC|BREAK|CONT) occur when
356 * a dotcmd is in a loop or a function body and appropriate
357 * built-ins occurs in file scope in the sourced file. Values
358 * other than SKIPFILE are reset by the appropriate eval*()
359 * that contained the dotcmd() call.
360 */
361 skip = current_skipstate();
362 if (skip != SKIPNONE) {
363 if (skip == SKIPFILE)
364 stop_skipping();
365 break;
366 }
367 }
368 popstackmark(&smark);
369 }
370
371
372
373 /*
374 * Read /etc/profile or .profile. Return on error.
375 */
376
377 STATIC void
read_profile(const char * name)378 read_profile(const char *name)
379 {
380 int fd;
381 int xflag_set = 0;
382 int vflag_set = 0;
383
384 if (*name == '\0')
385 return;
386
387 INTOFF;
388 if ((fd = open(name, O_RDONLY)) >= 0)
389 setinputfd(fd, 1);
390 INTON;
391 if (fd < 0)
392 return;
393 /* -q turns off -x and -v just when executing init files */
394 if (qflag) {
395 if (xflag)
396 xflag = 0, xflag_set = 1;
397 if (vflag)
398 vflag = 0, vflag_set = 1;
399 }
400 (void)set_dot_funcnest(1); /* allow profile to "return" */
401 cmdloop(0);
402 (void)set_dot_funcnest(0);
403 if (qflag) {
404 if (xflag_set)
405 xflag = 1;
406 if (vflag_set)
407 vflag = 1;
408 }
409 popfile();
410 }
411
412
413
414 /*
415 * Read a file containing shell functions.
416 */
417
418 void
readcmdfile(char * name)419 readcmdfile(char *name)
420 {
421 int fd;
422
423 INTOFF;
424 if ((fd = open(name, O_RDONLY)) >= 0)
425 setinputfd(fd, 1);
426 else
427 error("Can't open %s", name);
428 INTON;
429 cmdloop(0);
430 popfile();
431 }
432
433
434
435 int
exitcmd(int argc,char ** argv)436 exitcmd(int argc, char **argv)
437 {
438 if (stoppedjobs())
439 return 0;
440 if (argc > 1)
441 exitshell(number(argv[1]));
442 else
443 exitshell_savedstatus();
444 /* NOTREACHED */
445 }
446