main.c

操作系统源代码

/*-
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1991 The Regents of the University of California.\n\
 All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)main.c	5.2 (Berkeley) 3/13/91";
#endif /* not lint */

#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>
#include "shell.h"
#include "main.h"
#include "mail.h"
#include "options.h"
#include "output.h"
#include "parser.h"
#include "nodes.h"
#include "eval.h"
#include "jobs.h"
#include "input.h"
#include "trap.h"
#if ATTY
#include "var.h"
#endif
#include "memalloc.h"
#include "error.h"
#include "init.h"
#include "mystring.h"

#define PROFILE 0

int rootpid;
int rootshell;
STATIC union node *curcmd;
STATIC union node *prevcmd;
extern int errno;
#if PROFILE
short profile_buf[16384];
extern int etext();
#endif

#ifdef __STDC__
STATIC void read_profile(char *);
char *getenv(char *);
#else
STATIC void read_profile();
char *getenv();
#endif


/*
 * Main routine.  We initialize things, parse the arguments, execute
 * profiles if we're a login shell, and then call cmdloop to execute
 * commands.  The setjmp call sets up the location to jump to when an
 * exception occurs.  When an exception occurs the variable "state"
 * is used to figure out how far we had gotten.
 */

main(argc, argv)  char **argv; {
	struct jmploc jmploc;
	struct stackmark smark;
	volatile int state;
	char *shinit, *home;
	char *profile = NULL, *ashrc = NULL;

#if PROFILE
	monitor(4, etext, profile_buf, sizeof profile_buf, 50);
#endif
	state = 0;
	if (setjmp(jmploc.loc)) {
		/*
		 * When a shell procedure is executed, we raise the
		 * exception EXSHELLPROC to clean up before executing
		 * the shell procedure.
		 */
		if (exception == EXSHELLPROC) {
			rootpid = getpid();
			rootshell = 1;
			minusc = NULL;
			state = 3;
		} else if (state == 0 || iflag == 0 || ! rootshell)
			exitshell(2);
		reset();
#if ATTY
		if (exception == EXINT
		 && (! attyset() || equal(termval(), "emacs"))) {
#else
		if (exception == EXINT) {
#endif
			out2c('\n');
			flushout(&errout);
		}
		popstackmark(&smark);
		FORCEINTON;				/* enable interrupts */
		if (state == 1)
			goto state1;
		else if (state == 2)
			goto state2;
		else if (state == 3)
			goto state3;
		else
			goto state4;
	}
	handler = &jmploc;
#if DEBUG
	opentrace();
	trputs("Shell args:  ");  trargs(argv);
#endif
	rootpid = getpid();
	rootshell = 1;
	init();
	setstackmark(&smark);
	procargs(argc, argv);
	if (argv[0] && argv[0][0] == '-') {
		state = 1;
		read_profile("/etc/profile");
state1:
		state = 2;
		if ((home = getenv("HOME")) != NULL
		    && (profile = (char *) malloc(strlen(home) + 10)) != NULL)
		{
			strcpy(profile, home);
			strcat(profile, "/.profile");
			read_profile(profile);
		} else {
			read_profile(".profile");
		}
	} else if ((sflag || minusc) && (shinit = getenv("SHINIT")) != NULL) {
		state = 2;
		evalstring(shinit);
	}
state2:
	if (profile != NULL) free(profile);

	state = 3;
	if (!argv[0] || argv[0][0] != '-') {
		if ((home = getenv("HOME")) != NULL
			&& (ashrc = (char *) malloc(strlen(home) + 8)) != NULL)
		{
			strcpy(ashrc, home);
			strcat(ashrc, "/.ashrc");
			read_profile(ashrc);
		}
	}
state3:
	if (ashrc != NULL) free(ashrc);
	state = 4;
	if (minusc) {
		evalstring(minusc);
	}
	if (sflag || minusc == NULL) {
state4:
		cmdloop(1);
	}
#if PROFILE
	monitor(0);
#endif
	exitshell(exitstatus);
}


/*
 * Read and execute commands.  "Top" is nonzero for the top level command
 * loop; it turns on prompting if the shell is interactive.
 */

void
cmdloop(top) {
	union node *n;
	struct stackmark smark;
	int inter;
	int numeof;

	TRACE(("cmdloop(%d) called\n", top));
	setstackmark(&smark);
	numeof = 0;
	for (;;) {
		if (pendingsigs)
			dotrap();
		inter = 0;
		if (iflag && top) {
			inter++;
			showjobs(1);
			chkmail(0);
			flushout(&output);
		}
		n = parsecmd(inter);
#if DEBUG
		/* showtree(n); */
#endif
		if (n == NEOF) {
			if (Iflag == 0 || numeof >= 50)
				break;
			out2str("\nUse \"exit\" to leave shell.\n");
			numeof++;
		} else if (n != NULL && nflag == 0) {
			if (inter) {
				INTOFF;
				if (prevcmd)
					freefunc(prevcmd);
				prevcmd = curcmd;
				curcmd = copyfunc(n);
				INTON;
			}
			evaltree(n, 0);
#ifdef notdef
			if (exitstatus)				      /*DEBUG*/
				outfmt(&errout, "Exit status 0x%X\n", exitstatus);
#endif
		}
		popstackmark(&smark);
	}
	popstackmark(&smark);		/* unnecessary */
}



/*
 * Read /etc/profile or .profile.  Return on error.
 */

STATIC void
read_profile(name)
	char *name;
	{
	int fd;

	INTOFF;
	if ((fd = open(name, O_RDONLY)) >= 0)
		setinputfd(fd, 1);
	INTON;
	if (fd < 0)
		return;
	cmdloop(0);
	popfile();
}



/*
 * Read a file containing shell functions.
 */

void
readcmdfile(name)
	char *name;
	{
	int fd;

	INTOFF;
	if ((fd = open(name, O_RDONLY)) >= 0)
		setinputfd(fd, 1);
	else
		error("Can't open %s", name);
	INTON;
	cmdloop(0);
	popfile();
}


/*
 * Take commands from a file.  To be compatable we should do a path
 * search for the file, but a path search doesn't make any sense.
 */

dotcmd(argc, argv)  char **argv; {
	exitstatus = 0;
	if (argc >= 2) {		/* That's what SVR2 does */
		setinputfile(argv[1], 1);
		commandname = argv[1];
		cmdloop(0);
		popfile();
	}
	return exitstatus;
}


exitcmd(argc, argv)  char **argv; {
	if (argc > 1)
		exitstatus = number(argv[1]);
	exitshell(exitstatus);
}


lccmd(argc, argv)  char **argv; {
	if (argc > 1) {
		defun(argv[1], prevcmd);
		return 0;
	} else {
		INTOFF;
		freefunc(curcmd);
		curcmd = prevcmd;
		prevcmd = NULL;
		INTON;
		evaltree(curcmd, 0);
		return exitstatus;
	}
}



#ifdef notdef
/*
 * Should never be called.
 */

void
exit(exitstatus) {
	_exit(exitstatus);
}
#endif