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main.c revision 1.84 
      1 /*	$NetBSD: main.c,v 1.84 2020/02/06 20:08:28 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 1.84 2020/02/06 20:08:28 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 <stdlib.h>
     55 #include <locale.h>
     56 #include <fcntl.h>
     57 
     58 
     59 #include "shell.h"
     60 #include "main.h"
     61 #include "mail.h"
     62 #include "options.h"
     63 #include "builtins.h"
     64 #include "output.h"
     65 #include "parser.h"
     66 #include "nodes.h"
     67 #include "expand.h"
     68 #include "eval.h"
     69 #include "jobs.h"
     70 #include "input.h"
     71 #include "trap.h"
     72 #include "var.h"
     73 #include "show.h"
     74 #include "memalloc.h"
     75 #include "error.h"
     76 #include "init.h"
     77 #include "mystring.h"
     78 #include "exec.h"
     79 #include "cd.h"
     80 #include "redir.h"
     81 
     82 #define PROFILE 0
     83 
     84 int rootpid;
     85 int rootshell;
     86 struct jmploc main_handler;
     87 int max_user_fd;
     88 #if PROFILE
     89 short profile_buf[16384];
     90 extern int etext();
     91 #endif
     92 
     93 STATIC void read_profile(const char *);
     94 
     95 /*
     96  * Main routine.  We initialize things, parse the arguments, execute
     97  * profiles if we're a login shell, and then call cmdloop to execute
     98  * commands.  The setjmp call sets up the location to jump to when an
     99  * exception occurs.  When an exception occurs the variable "state"
    100  * is used to figure out how far we had gotten.
    101  */
    102 
    103 int
    104 main(int argc, char **argv)
    105 {
    106 	struct stackmark smark;
    107 	volatile int state;
    108 	char *shinit;
    109 	uid_t uid;
    110 	gid_t gid;
    111 	sigset_t sigs;
    112 
    113 	/*
    114 	 * If we happen to be invoked with SIGCHLD ignored, we cannot
    115 	 * successfully do almost anything.   Perhaps we should remember
    116 	 * its state and pass it on ignored to children if it was ignored
    117 	 * on entry, but that seems like just leaving the shit on the
    118 	 * footpath for someone else to fall into...
    119 	 */
    120 	(void)signal(SIGCHLD, SIG_DFL);
    121 	/*
    122 	 * Similarly, SIGCHLD must not be blocked
    123 	 */
    124 	sigemptyset(&sigs);
    125 	sigaddset(&sigs, SIGCHLD);
    126 	sigprocmask(SIG_UNBLOCK, &sigs, NULL);
    127 
    128 	uid = getuid();
    129 	gid = getgid();
    130 
    131 	max_user_fd = fcntl(0, F_MAXFD);
    132 	if (max_user_fd < 2)
    133 		max_user_fd = 2;
    134 
    135 	setlocale(LC_ALL, "");
    136 
    137 	posix = getenv("POSIXLY_CORRECT") != NULL;
    138 #if PROFILE
    139 	monitor(4, etext, profile_buf, sizeof profile_buf, 50);
    140 #endif
    141 	state = 0;
    142 	if (setjmp(main_handler.loc)) {
    143 		/*
    144 		 * When a shell procedure is executed, we raise the
    145 		 * exception EXSHELLPROC to clean up before executing
    146 		 * the shell procedure.
    147 		 */
    148 		switch (exception) {
    149 		case EXSHELLPROC:
    150 			rootpid = getpid();
    151 			rootshell = 1;
    152 			minusc = NULL;
    153 			state = 3;
    154 			break;
    155 
    156 		case EXEXEC:
    157 			exitstatus = exerrno;
    158 			break;
    159 
    160 		case EXERROR:
    161 			exitstatus = 2;
    162 			break;
    163 
    164 		default:
    165 			break;
    166 		}
    167 
    168 		if (exception != EXSHELLPROC) {
    169 			if (state == 0 || iflag == 0 || ! rootshell ||
    170 			    exception == EXEXIT)
    171 				exitshell(exitstatus);
    172 		}
    173 		reset();
    174 		if (exception == EXINT) {
    175 			out2c('\n');
    176 			flushout(&errout);
    177 		}
    178 		popstackmark(&smark);
    179 		FORCEINTON;				/* enable interrupts */
    180 		if (state == 1)
    181 			goto state1;
    182 		else if (state == 2)
    183 			goto state2;
    184 		else if (state == 3)
    185 			goto state3;
    186 		else
    187 			goto state4;
    188 	}
    189 	handler = &main_handler;
    190 #ifdef DEBUG
    191 #if DEBUG >= 2
    192 	debug = 1;	/* this may be reset by procargs() later */
    193 #endif
    194 	opentrace();
    195 	trputs("Shell args:  ");  trargs(argv);
    196 #if DEBUG >= 3
    197 	set_debug(((DEBUG)==3 ? "_@" : "++"), 1);
    198 #endif
    199 #endif
    200 	rootpid = getpid();
    201 	rootshell = 1;
    202 	init();
    203 	initpwd();
    204 	setstackmark(&smark);
    205 	procargs(argc, argv);
    206 
    207 	/*
    208 	 * Limit bogus system(3) or popen(3) calls in setuid binaries,
    209 	 * by requiring the -p flag
    210 	 */
    211 	if (!pflag && (uid != geteuid() || gid != getegid())) {
    212 		setuid(uid);
    213 		setgid(gid);
    214 		/* PS1 might need to be changed accordingly. */
    215 		choose_ps1();
    216 	}
    217 
    218 	if (argv[0] && argv[0][0] == '-') {
    219 		state = 1;
    220 		read_profile("/etc/profile");
    221  state1:
    222 		state = 2;
    223 		read_profile(".profile");
    224 	}
    225  state2:
    226 	state = 3;
    227 	if ((iflag || !posix) &&
    228 	    getuid() == geteuid() && getgid() == getegid()) {
    229 		struct stackmark env_smark;
    230 
    231 		setstackmark(&env_smark);
    232 		if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') {
    233 			state = 3;
    234 			read_profile(expandenv(shinit));
    235 		}
    236 		popstackmark(&env_smark);
    237 	}
    238  state3:
    239 	state = 4;
    240 	line_number = 1;	/* undo anything from profile files */
    241 
    242 	if (sflag == 0 || minusc) {
    243 		static int sigs[] =  {
    244 		    SIGINT, SIGQUIT, SIGHUP,
    245 #ifdef SIGTSTP
    246 		    SIGTSTP,
    247 #endif
    248 		    SIGPIPE
    249 		};
    250 #define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0]))
    251 		size_t i;
    252 
    253 		for (i = 0; i < SIGSSIZE; i++)
    254 		    setsignal(sigs[i], 0);
    255 	}
    256 
    257 	if (minusc)
    258 		evalstring(minusc, sflag ? 0 : EV_EXIT);
    259 
    260 	if (sflag || minusc == NULL) {
    261  state4:	/* XXX ??? - why isn't this before the "if" statement */
    262 		cmdloop(1);
    263 		if (iflag) {
    264 			out2str("\n");
    265 			flushout(&errout);
    266 		}
    267 	}
    268 #if PROFILE
    269 	monitor(0);
    270 #endif
    271 	line_number = plinno;
    272 	exitshell(exitstatus);
    273 	/* NOTREACHED */
    274 }
    275 
    276 
    277 /*
    278  * Read and execute commands.  "Top" is nonzero for the top level command
    279  * loop; it turns on prompting if the shell is interactive.
    280  */
    281 
    282 void
    283 cmdloop(int top)
    284 {
    285 	union node *n;
    286 	struct stackmark smark;
    287 	int inter;
    288 	int numeof = 0;
    289 	enum skipstate skip;
    290 
    291 	CTRACE(DBG_ALWAYS, ("cmdloop(%d) called\n", top));
    292 	setstackmark(&smark);
    293 	for (;;) {
    294 		if (pendingsigs)
    295 			dotrap();
    296 		inter = 0;
    297 		if (iflag == 1 && top) {
    298 			inter = 1;
    299 			showjobs(out2, SHOW_CHANGED);
    300 			chkmail(0);
    301 			flushout(&errout);
    302 			nflag = 0;
    303 		}
    304 		n = parsecmd(inter);
    305 		VXTRACE(DBG_PARSE|DBG_EVAL|DBG_CMDS,("cmdloop: "),showtree(n));
    306 		if (n == NEOF) {
    307 			if (!top || numeof >= 50)
    308 				break;
    309 			if (nflag)
    310 				break;
    311 			if (!stoppedjobs()) {
    312 				if (!iflag || !Iflag)
    313 					break;
    314 				out2str("\nUse \"exit\" to leave shell.\n");
    315 			}
    316 			numeof++;
    317 		} else if (n != NULL && nflag == 0) {
    318 			job_warning = (job_warning == 2) ? 1 : 0;
    319 			numeof = 0;
    320 			evaltree(n, 0);
    321 		}
    322 		rststackmark(&smark);
    323 
    324 		/*
    325 		 * Any SKIP* can occur here!  SKIP(FUNC|BREAK|CONT) occur when
    326 		 * a dotcmd is in a loop or a function body and appropriate
    327 		 * built-ins occurs in file scope in the sourced file.  Values
    328 		 * other than SKIPFILE are reset by the appropriate eval*()
    329 		 * that contained the dotcmd() call.
    330 		 */
    331 		skip = current_skipstate();
    332 		if (skip != SKIPNONE) {
    333 			if (skip == SKIPFILE)
    334 				stop_skipping();
    335 			break;
    336 		}
    337 	}
    338 	popstackmark(&smark);
    339 }
    340 
    341 
    342 
    343 /*
    344  * Read /etc/profile or .profile.  Return on error.
    345  */
    346 
    347 STATIC void
    348 read_profile(const char *name)
    349 {
    350 	int fd;
    351 	int xflag_set = 0;
    352 	int vflag_set = 0;
    353 
    354 	if (*name == '\0')
    355 		return;
    356 
    357 	INTOFF;
    358 	if ((fd = open(name, O_RDONLY)) >= 0)
    359 		setinputfd(fd, 1);
    360 	INTON;
    361 	if (fd < 0)
    362 		return;
    363 	/* -q turns off -x and -v just when executing init files */
    364 	if (qflag)  {
    365 	    if (xflag)
    366 		    xflag = 0, xflag_set = 1;
    367 	    if (vflag)
    368 		    vflag = 0, vflag_set = 1;
    369 	}
    370 	(void)set_dot_funcnest(1);	/* allow profile to "return" */
    371 	cmdloop(0);
    372 	(void)set_dot_funcnest(0);
    373 	if (qflag)  {
    374 	    if (xflag_set)
    375 		    xflag = 1;
    376 	    if (vflag_set)
    377 		    vflag = 1;
    378 	}
    379 	popfile();
    380 }
    381 
    382 
    383 
    384 /*
    385  * Read a file containing shell functions.
    386  */
    387 
    388 void
    389 readcmdfile(char *name)
    390 {
    391 	int fd;
    392 
    393 	INTOFF;
    394 	if ((fd = open(name, O_RDONLY)) >= 0)
    395 		setinputfd(fd, 1);
    396 	else
    397 		error("Can't open %s", name);
    398 	INTON;
    399 	cmdloop(0);
    400 	popfile();
    401 }
    402 
    403 
    404 
    405 int
    406 exitcmd(int argc, char **argv)
    407 {
    408 	if (stoppedjobs())
    409 		return 0;
    410 	if (argc > 1)
    411 		exitshell(number(argv[1]));
    412 	else
    413 		exitshell_savedstatus();
    414 	/* NOTREACHED */
    415 }
    416