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main.c revision 1.79 
      1 /*	$NetBSD: main.c,v 1.79 2018/12/11 13:31:20 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 1.79 2018/12/11 13:31:20 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 
    112 	uid = getuid();
    113 	gid = getgid();
    114 
    115 	max_user_fd = fcntl(0, F_MAXFD);
    116 	if (max_user_fd < 2)
    117 		max_user_fd = 2;
    118 
    119 	setlocale(LC_ALL, "");
    120 
    121 	posix = getenv("POSIXLY_CORRECT") != NULL;
    122 #if PROFILE
    123 	monitor(4, etext, profile_buf, sizeof profile_buf, 50);
    124 #endif
    125 	state = 0;
    126 	if (setjmp(main_handler.loc)) {
    127 		/*
    128 		 * When a shell procedure is executed, we raise the
    129 		 * exception EXSHELLPROC to clean up before executing
    130 		 * the shell procedure.
    131 		 */
    132 		switch (exception) {
    133 		case EXSHELLPROC:
    134 			rootpid = getpid();
    135 			rootshell = 1;
    136 			minusc = NULL;
    137 			state = 3;
    138 			break;
    139 
    140 		case EXEXEC:
    141 			exitstatus = exerrno;
    142 			break;
    143 
    144 		case EXERROR:
    145 			exitstatus = 2;
    146 			break;
    147 
    148 		default:
    149 			break;
    150 		}
    151 
    152 		if (exception != EXSHELLPROC) {
    153 			if (state == 0 || iflag == 0 || ! rootshell ||
    154 			    exception == EXEXIT)
    155 				exitshell(exitstatus);
    156 		}
    157 		reset();
    158 		if (exception == EXINT) {
    159 			out2c('\n');
    160 			flushout(&errout);
    161 		}
    162 		popstackmark(&smark);
    163 		FORCEINTON;				/* enable interrupts */
    164 		if (state == 1)
    165 			goto state1;
    166 		else if (state == 2)
    167 			goto state2;
    168 		else if (state == 3)
    169 			goto state3;
    170 		else
    171 			goto state4;
    172 	}
    173 	handler = &main_handler;
    174 #ifdef DEBUG
    175 #if DEBUG >= 2
    176 	debug = 1;	/* this may be reset by procargs() later */
    177 #endif
    178 	opentrace();
    179 	trputs("Shell args:  ");  trargs(argv);
    180 #if DEBUG >= 3
    181 	set_debug(((DEBUG)==3 ? "_@" : "++"), 1);
    182 #endif
    183 #endif
    184 	rootpid = getpid();
    185 	rootshell = 1;
    186 	init();
    187 	initpwd();
    188 	setstackmark(&smark);
    189 	procargs(argc, argv);
    190 
    191 	/*
    192 	 * Limit bogus system(3) or popen(3) calls in setuid binaries,
    193 	 * by requiring the -p flag
    194 	 */
    195 	if (!pflag && (uid != geteuid() || gid != getegid())) {
    196 		setuid(uid);
    197 		setgid(gid);
    198 		/* PS1 might need to be changed accordingly. */
    199 		choose_ps1();
    200 	}
    201 
    202 	if (argv[0] && argv[0][0] == '-') {
    203 		state = 1;
    204 		read_profile("/etc/profile");
    205  state1:
    206 		state = 2;
    207 		read_profile(".profile");
    208 	}
    209  state2:
    210 	state = 3;
    211 	if ((iflag || !posix) &&
    212 	    getuid() == geteuid() && getgid() == getegid()) {
    213 		struct stackmark env_smark;
    214 
    215 		setstackmark(&env_smark);
    216 		if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') {
    217 			state = 3;
    218 			read_profile(expandenv(shinit));
    219 		}
    220 		popstackmark(&env_smark);
    221 	}
    222  state3:
    223 	state = 4;
    224 	line_number = 1;	/* undo anything from profile files */
    225 
    226 	if (sflag == 0 || minusc) {
    227 		static int sigs[] =  {
    228 		    SIGINT, SIGQUIT, SIGHUP,
    229 #ifdef SIGTSTP
    230 		    SIGTSTP,
    231 #endif
    232 		    SIGPIPE
    233 		};
    234 #define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0]))
    235 		size_t i;
    236 
    237 		for (i = 0; i < SIGSSIZE; i++)
    238 		    setsignal(sigs[i], 0);
    239 	}
    240 
    241 	if (minusc)
    242 		evalstring(minusc, sflag ? 0 : EV_EXIT);
    243 
    244 	if (sflag || minusc == NULL) {
    245  state4:	/* XXX ??? - why isn't this before the "if" statement */
    246 		cmdloop(1);
    247 	}
    248 #if PROFILE
    249 	monitor(0);
    250 #endif
    251 	exitshell(exitstatus);
    252 	/* NOTREACHED */
    253 }
    254 
    255 
    256 /*
    257  * Read and execute commands.  "Top" is nonzero for the top level command
    258  * loop; it turns on prompting if the shell is interactive.
    259  */
    260 
    261 void
    262 cmdloop(int top)
    263 {
    264 	union node *n;
    265 	struct stackmark smark;
    266 	int inter;
    267 	int numeof = 0;
    268 	enum skipstate skip;
    269 
    270 	CTRACE(DBG_ALWAYS, ("cmdloop(%d) called\n", top));
    271 	setstackmark(&smark);
    272 	for (;;) {
    273 		if (pendingsigs)
    274 			dotrap();
    275 		inter = 0;
    276 		if (iflag == 1 && top) {
    277 			inter = 1;
    278 			showjobs(out2, SHOW_CHANGED);
    279 			chkmail(0);
    280 			flushout(&errout);
    281 			nflag = 0;
    282 		}
    283 		n = parsecmd(inter);
    284 		VXTRACE(DBG_PARSE|DBG_EVAL|DBG_CMDS,("cmdloop: "),showtree(n));
    285 		if (n == NEOF) {
    286 			if (!top || numeof >= 50)
    287 				break;
    288 			if (nflag)
    289 				break;
    290 			if (!stoppedjobs()) {
    291 				if (!iflag || !Iflag)
    292 					break;
    293 				out2str("\nUse \"exit\" to leave shell.\n");
    294 			}
    295 			numeof++;
    296 		} else if (n != NULL && nflag == 0) {
    297 			job_warning = (job_warning == 2) ? 1 : 0;
    298 			numeof = 0;
    299 			evaltree(n, 0);
    300 		}
    301 		rststackmark(&smark);
    302 
    303 		/*
    304 		 * Any SKIP* can occur here!  SKIP(FUNC|BREAK|CONT) occur when
    305 		 * a dotcmd is in a loop or a function body and appropriate
    306 		 * built-ins occurs in file scope in the sourced file.  Values
    307 		 * other than SKIPFILE are reset by the appropriate eval*()
    308 		 * that contained the dotcmd() call.
    309 		 */
    310 		skip = current_skipstate();
    311 		if (skip != SKIPNONE) {
    312 			if (skip == SKIPFILE)
    313 				stop_skipping();
    314 			break;
    315 		}
    316 	}
    317 	popstackmark(&smark);
    318 }
    319 
    320 
    321 
    322 /*
    323  * Read /etc/profile or .profile.  Return on error.
    324  */
    325 
    326 STATIC void
    327 read_profile(const char *name)
    328 {
    329 	int fd;
    330 	int xflag_set = 0;
    331 	int vflag_set = 0;
    332 
    333 	if (*name == '\0')
    334 		return;
    335 
    336 	INTOFF;
    337 	if ((fd = open(name, O_RDONLY)) >= 0)
    338 		setinputfd(fd, 1);
    339 	INTON;
    340 	if (fd < 0)
    341 		return;
    342 	/* -q turns off -x and -v just when executing init files */
    343 	if (qflag)  {
    344 	    if (xflag)
    345 		    xflag = 0, xflag_set = 1;
    346 	    if (vflag)
    347 		    vflag = 0, vflag_set = 1;
    348 	}
    349 	cmdloop(0);
    350 	if (qflag)  {
    351 	    if (xflag_set)
    352 		    xflag = 1;
    353 	    if (vflag_set)
    354 		    vflag = 1;
    355 	}
    356 	popfile();
    357 }
    358 
    359 
    360 
    361 /*
    362  * Read a file containing shell functions.
    363  */
    364 
    365 void
    366 readcmdfile(char *name)
    367 {
    368 	int fd;
    369 
    370 	INTOFF;
    371 	if ((fd = open(name, O_RDONLY)) >= 0)
    372 		setinputfd(fd, 1);
    373 	else
    374 		error("Can't open %s", name);
    375 	INTON;
    376 	cmdloop(0);
    377 	popfile();
    378 }
    379 
    380 
    381 
    382 int
    383 exitcmd(int argc, char **argv)
    384 {
    385 	if (stoppedjobs())
    386 		return 0;
    387 	if (argc > 1)
    388 		exitshell(number(argv[1]));
    389 	else
    390 		exitshell_savedstatus();
    391 	/* NOTREACHED */
    392 }
    393