sh.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 1,098 行 · 第 1/2 页

#ifndef lint
static  char    *sccsid = "@(#)sh.c	4.2  (ULTRIX)        8/13/90";
#endif lint
/************************************************************************
 *									*
 *			Copyright (c) 1988 by				*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/

/*
 * C Shell
 *
 * Bill Joy, UC Berkeley, California, USA
 * October 1978, May 1980
 *
 * Jim Kulp, IIASA, Laxenburg, Austria
 * April 1980
 *
 * Modification History:
 *
 * 005 - Bob Fontaine - Thu Jun 21 10:22:20 EDT 1990
 *	change name of csh internal printf function to csh_printf to avoid
 *	conflicts with printf function in stdio library.
 *
 * 004 - Bob Fontaine - Fri May 25 10:00:14 EDT 1990
 *	Stat argument to source command and make sure file exists and
 *	that it is a regular file (ie that it is not a directory, pipe ...).
 *	Fix for QAR# 3835
 *
 * 003 - Gary A. Gaudet - Thu Dec 28 17:31:15 EST 1989
 *	Added comments; removed code not compiled.
 *
 * 02	12-Nov-88, Al Delorey (afd).
 *	Use "ifdef CSHEDIT" around the cmd line edit code.
 *
 * 01	20-Sep-88, Al Delorey (afd)
 *	Added command line edit capability (search for "edit" to find changes).
 *	Deleted Mips tsh_init call.
 */

#include "sh.h"
#include <sys/ioctl.h>
char 	*word();
#ifdef CSHEDIT
char 	*editword();
#endif
char	*pathlist[] =	{ ".", "/usr/ucb", "/bin", "/usr/bin", 0 };
char	*dumphist[] =	{ "history", "-h", 0, 0 };
char	*loadhist[] =	{ "source", "-h", "~/.history", 0 };
char	HIST = '!';
char	HISTSUB = '^';
bool	nofile;
bool	reenter;
bool	nverbose;
bool	nexececho;
bool	quitit;
bool	fast;
bool	batch;
bool	prompt = 1;
bool	enterhist = 0;

extern	gid_t getegid(), getgid();
extern	uid_t geteuid(), getuid();

main(c, av)
	int c;
	char **av;
{
	register char **v, *cp;
	register int f;
	struct sigvec osv;

/*
 *	immediately establish a timing base
 */
	settimes();
	v = av;
/*
 *	a.out's are quittable
 */
	if (eq(v[0], "a.out"))
		quitit = 1;
/*
 *	get user id
 */
	uid = getuid();
/*
 *	login shell if "-csh" with no arguments
 */
	loginsh = **v == '-' && c == 1;
	if (loginsh)
		(void) time(&chktim);

	/*
	 * Move the descriptors to safe places.
	 * The variable didfds is 0 while we have only FSH* to work with.
	 * When didfds is true, we have 0,1,2 and prefer to use these.
	 */
	initdesc();

	/*
	 * Initialize the shell variables.
	 * ARGV and PROMPT are initialized later.
	 * STATUS is also munged in several places.
	 * CHILD is munged when forking/waiting
	 */

	set("status", "0");
	dinit(cp = getenv("HOME"));	/* dinit thinks that HOME == cwd in a
					 * login shell */
	if (cp == NOSTR)
		fast++;			/* No home -> can't read scripts */
	else
		set("home", savestr(cp));
	/*
	 * Grab other useful things from the environment.
	 * Should we grab everything??
	 */
	if ((cp = getenv("USER")) != NOSTR)
		set("user", savestr(cp));
	if ((cp = getenv("TERM")) != NOSTR)
		set("term", savestr(cp));
	/*
	 * Re-initialize path if set in environment
	 */
	if ((cp = getenv("PATH")) == NOSTR)
		set1("path", saveblk(pathlist), &shvhed);
	else
		importpath(cp);
	set("shell", SHELLPATH);

	doldol = putn(getpid());		/* For $$ */
	shtemp = strspl("/tmp/sh", doldol);	/* For << */

	/*
	 * Record the interrupt states from the parent process.
	 * If the parent is non-interruptible our hand must be forced
	 * or we (and our children) won't be either.
	 * Our children inherit termination from our parent.
	 * We catch it only if we are the login shell.
	 */
		/* parents interruptibility */
	(void) sigvec(SIGINT, (struct sigvec *)0, &osv);
	parintr = osv.sv_handler;
		/* parents terminability */
	(void) sigvec(SIGTERM, (struct sigvec *)0, &osv);
	parterm = osv.sv_handler;
	if (loginsh) {
		(void) signal(SIGHUP, phup);	/* exit processing on HUP */
		(void) signal(SIGXCPU, phup);	/* ...and on XCPU */
		(void) signal(SIGXFSZ, phup);	/* ...and on XFSZ */
	}

	/*
	 * Process the arguments.
	 *
	 * Note that processing of -v/-x is actually delayed till after
	 * script processing.
	 */
	c--, v++;
	while (c > 0 && (cp = v[0])[0] == '-' && *++cp != '\0' && !batch) {
		do switch (*cp++) {

		case 'b':		/* -b	Next arg is input file */
			batch++;
			break;

		case 'c':		/* -c	Command input from arg */
			if (c == 1) {
				exit(0);
			}
			c--, v++;
			arginp = v[0];
			prompt = 0;
			nofile++;
			break;

		case 'e':		/* -e	Exit on any error */
			exiterr++;
			break;

		case 'f':		/* -f	Fast start */
			fast++;
			break;

		case 'i':		/* -i	Interactive, even if !intty */
			intact++;
			nofile++;
			break;

		case 'n':		/* -n	Don't execute */
			noexec++;
			break;

		case 'q':		/* -q	(Undoc'd) ... die on quit */
			quitit = 1;
			break;

		case 's':		/* -s	Read from std input */
			nofile++;
			break;

		case 't':		/* -t	Read one line from input */
			onelflg = 2;
			prompt = 0;
			nofile++;
			break;

		case 'v':		/* -v	Echo hist expanded input */
			nverbose = 1;			/* ... later */
			break;

		case 'x':		/* -x	Echo just before execution */
			nexececho = 1;			/* ... later */
			break;

		case 'V':		/* -V	Echo hist expanded input */
			setNS("verbose");		/* NOW! */
			break;

		case 'X':		/* -X	Echo just before execution */
			setNS("echo");			/* NOW! */
			break;

		} while (*cp);
		v++, c--;
	}

	if (quitit)			/* With all due haste, for debugging */
		(void) signal(SIGQUIT, SIG_DFL);

	/*
	 * Unless prevented by -c, -i, -s, or -t, if there
	 * are remaining arguments the first of them is the name
	 * of a shell file from which to read commands.
	 */
	if (nofile == 0 && c > 0) {
		nofile = open(v[0], 0);
		if (nofile < 0) {
			child++;		/* So this ... */
			Perror(v[0]);		/* ... doesn't return */
		}
		file = v[0];
		SHIN = dmove(nofile, FSHIN);	/* Replace FSHIN */
		prompt = 0;
		c--, v++;
	}
	if (!batch && (uid != geteuid() || getgid() != getegid())) {
		errno = EACCES;
		child++;			/* So this ... */
		Perror("csh");			/* ... doesn't return */
	}
	/*
	 * Consider input a tty if it really is or we are interactive.
	 */
	intty = intact || isatty(SHIN);
	/*
	 * Decide whether we should play with signals or not.
	 * If we are explicitly told (via -i, or -) or we are a login
	 * shell (arg0 starts with -) or the input and output are both
	 * the ttys("csh", or "csh</dev/ttyx>/dev/ttyx")
	 * Note that in only the login shell is it likely that parent
	 * may have set signals to be ignored
	 */
	if (loginsh || intact || intty && isatty(SHOUT))
		setintr = 1;
#ifdef TELL
	settell();
#endif
	/*
	 * Save the remaining arguments in argv.
	 */
	setq("argv", v, &shvhed);

	/*
	 * Set up the prompt.
	 */
	if (prompt)
		set("prompt", uid == 0 ? "# " : "% ");

	/*
	 * If we are an interactive shell, then start fiddling
	 * with the signals; this is a tricky game.
	 */
	shpgrp = getpgrp(0);
	opgrp = tpgrp = -1;
	oldisc = -1;
	if (setintr) {
		**av = '-';
		if (!quitit)		/* Wary! */
			(void) signal(SIGQUIT, SIG_IGN);
		(void) signal(SIGINT, pintr);
		(void) sigblock(sigmask(SIGINT));
		(void) signal(SIGTERM, SIG_IGN);
		if (quitit == 0 && arginp == 0) {
			(void) signal(SIGTSTP, SIG_IGN);
			(void) signal(SIGTTIN, SIG_IGN);
			(void) signal(SIGTTOU, SIG_IGN);
			/*
			 * Wait till in foreground, in case someone
			 * stupidly runs
			 *	csh &
			 * dont want to try to grab away the tty.
			 */
			if (isatty(FSHDIAG))
				f = FSHDIAG;
			else if (isatty(FSHOUT))
				f = FSHOUT;
			else if (isatty(OLDSTD))
				f = OLDSTD;
			else
				f = -1;
retry:
			if (ioctl(f, TIOCGPGRP, (char *)&tpgrp) == 0 &&
			    tpgrp != -1) {
				int ldisc;
				if (tpgrp != shpgrp) {
					void (*old)() = signal(SIGTTIN,SIG_DFL);
					(void) kill(0, SIGTTIN);
					(void) signal(SIGTTIN, old);
					goto retry;
				}
				if (ioctl(f, TIOCGETD, (char *)&oldisc) != 0) 
					goto notty;
				if (oldisc != NTTYDISC) {
#ifdef DEBUG
					csh_printf("Switching to new tty driver...\n"); /* 005 RNF */
#endif DEBUG
					ldisc = NTTYDISC;
					(void) ioctl(f, TIOCSETD,
						(char *)&ldisc);
				} else
					oldisc = -1;
				opgrp = shpgrp;
				shpgrp = getpid();
				tpgrp = shpgrp;
				(void) ioctl(f, TIOCSPGRP, (char *)&shpgrp);
				(void) setpgrp(0, shpgrp);
				dcopy(f, FSHTTY);
				ioctl(FSHTTY, FIOCLEX, 0);
			} else {
notty:
  				csh_printf("Warning: no access to tty; thus no job control in this shell...\n"); /* 005 RNF */
				tpgrp = -1;
			}
		}
	}
	if (setintr == 0 && parintr == SIG_DFL)
		setintr++;
	(void) signal(SIGCHLD, pchild);	/* while signals not ready */

	/*
	 * Set an exit here in case of an interrupt or error reading
	 * the shell start-up scripts.
	 */
	setexit();
	haderr = 0;		/* In case second time through */
	if (!fast && reenter == 0) {
		reenter++;
		/* Will have value("home") here because set fast if don't */
		srccat(value("home"), "/.cshrc");
		if (!fast && !arginp && !onelflg && !havhash)
			dohash();
		if (loginsh) {
			srccat(value("home"), "/.login");
		}
		dosource(loadhist);
	}

	/*
	 * Now are ready for the -v and -x flags
	 */
	if (nverbose)
		setNS("verbose");
	if (nexececho)
		setNS("echo");

	/*
	 * All the rest of the world is inside this call.
	 * The argument to process indicates whether it should
	 * catch "error unwinds".  Thus if we are a interactive shell
	 * our call here will never return by being blown past on an error.
	 */
	process(setintr);

	/*
	 * Mop-up.
	 */
	if (loginsh) {
		csh_printf("logout\n");  		/* 005 RNF */
		(void) close(SHIN);
		child++;
		goodbye();
	}
	rechist();
	exitstat();
}

untty()
{

	if (tpgrp > 0) {
		(void) setpgrp(0, opgrp);
		(void) ioctl(FSHTTY, TIOCSPGRP, (char *)&opgrp);
		if (oldisc != -1 && oldisc != NTTYDISC) {
#ifdef DEBUG
			csh_printf("\nReverting to old tty driver...\n"); /* 005 RNF */
#endif DEBUG
			(void) ioctl(FSHTTY, TIOCSETD, (char *)&oldisc);
		}
	}
}

importpath(cp)
	char *cp;
{
	register int i = 0;
	register char *dp;
	register char **pv;
	int c;
	static char dot[2] = {'.', 0};

	for (dp = cp; *dp; dp++)
		if (*dp == ':')
			i++;
	/*
	 * i+2 where i is the number of colons in the path.
	 * There are i+1 directories in the path plus we need
	 * room for a zero terminator.
	 */
	pv = (char **) calloc((unsigned) (i + 2), sizeof (char **));
	dp = cp;
	i = 0;
	if (*dp)
	for (;;) {
		if ((c = *dp) == ':' || c == 0) {
			*dp = 0;
			pv[i++] = savestr(*cp ? cp : dot);
			if (c) {
				cp = dp + 1;
				*dp = ':';
			} else
				break;
		}
		dp++;
	}
	pv[i] = 0;
	set1("path", pv, &shvhed);
}

/*
 * Source to the file which is the catenation of the argument names.
 */
srccat(cp, dp)
	char *cp, *dp;
{
	register char *ep = strspl(cp, dp);
	register int unit = dmove(open(ep, 0), -1);
	xfree(ep);

/*
 * There is code here to prevent from automatically source'ing $home/.cshrc
 * and $home/.login if you don't own them. This probably isn't a good
 * idea in two cases:
 *
 *	1. A program may exist whose sole purpose is to change your uid
 *	   and groups without changing you to that user (for example, su -e
 *	   in some versions of Unix).
 *
 *	2. You may be sharing a home directory with someone else. This was
 *	   the case with a group I worked in once.
 */

#ifdef notdef
	srcunit(unit, 1, 0);
#else
	srcunit(unit, 0, 0);
#endif
}

/*
 * Source to a unit.  If onlyown it must be our file or our group or
 * we don't chance it.	This occurs on ".cshrc"s and the like.
 */
srcunit(unit, onlyown, hflg)
	register int unit;
	bool onlyown;
	bool hflg;
{
	/* We have to push down a lot of state here */
	/* All this could go into a structure */
	int oSHIN = -1, oldintty = intty;
	struct whyle *oldwhyl = whyles;
	char *ogointr = gointr, *oarginp = arginp;
	char *oevalp = evalp, **oevalvec = evalvec;
	int oonelflg = onelflg;
	bool oenterhist = enterhist;
	char OHIST = HIST;
#ifdef TELL
	bool otell = cantell;
#endif
	struct Bin saveB;

	/* The (few) real local variables */
	jmp_buf oldexit;
	int reenter, omask;

	if (unit < 0)
		return;
	if (didfds)
		donefds();
	if (onlyown) {
		struct stat stb;

		if (fstat(unit, &stb) < 0 ||
		    (stb.st_uid != uid && stb.st_gid != getgid())) {
			(void) close(unit);
			return;
		}
	}

	/*
	 * There is a critical section here while we are pushing down the
	 * input stream since we have stuff in different structures.
	 * If we weren't careful an interrupt could corrupt SHIN's Bin
	 * structure and kill the shell.
	 *