stdio based version; brace glob fix; builtin prototypes

[unix-history] / usr / src / bin / csh / csh.c

/*-
 * Copyright (c) 1980, 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#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[] = "@(#)csh.c	5.27 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <pwd.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>
#include <unistd.h>
#if __STDC__
# include <stdarg.h>
#else
# include <varargs.h>
#endif

#include "csh.h"
#include "extern.h"
#include "pathnames.h"

extern bool MapsAreInited;
extern bool NLSMapsAreInited;

/*
 * C Shell
 *
 * Bill Joy, UC Berkeley, California, USA
 * October 1978, May 1980
 *
 * Jim Kulp, IIASA, Laxenburg, Austria
 * April 1980
 *
 * Christos Zoulas, Cornell University
 * June, 1991
 */

Char   *dumphist[] = {STRhistory, STRmh, 0, 0};
Char   *loadhist[] = {STRsource, STRmh, STRhistfile, 0};

int     nofile = 0;
bool    reenter = 0;
bool    nverbose = 0;
bool    nexececho = 0;
bool    quitit = 0;
bool    fast = 0;
bool    batch = 0;
bool    mflag = 0;
bool    prompt = 1;
bool    enterhist = 0;
bool    tellwhat = 0;

extern char **environ;

static int	readf __P((void *, char *, int));
static fpos_t	seekf __P((void *, fpos_t, int));
static int	writef __P((void *, const char *, int));
static int	closef __P((void *));
static int	srccat __P((Char *, Char *));
static int	srcfile __P((char *, bool, bool));
static void	phup __P((int));
static void	srcunit __P((int, bool, bool));
static void	mailchk __P((void));
static Char   **defaultpath __P((void));

int
main(argc, argv)
    int     argc;
    char  **argv;
{
    register Char *cp;
    register char *tcp;
    register int f;
    register char **tempv;
    struct sigvec osv;

    cshin = stdin;
    cshout = stdout;
    csherr = stderr;

    settimes();			/* Immed. estab. timing base */

    /*
     * Initialize non constant strings
     */
#ifdef _PATH_BSHELL
    STR_BSHELL = SAVE(_PATH_BSHELL);
#endif
#ifdef _PATH_CSHELL
    STR_SHELLPATH = SAVE(_PATH_CSHELL);
#endif
    STR_environ = blk2short(environ);
    environ = short2blk(STR_environ);	/* So that we can free it */
    STR_WORD_CHARS = SAVE(WORD_CHARS);

    HIST = '!';
    HISTSUB = '^';
    word_chars = STR_WORD_CHARS;

    tempv = argv;
    if (eq(str2short(tempv[0]), STRaout))	/* A.out's are quittable */
	quitit = 1;
    uid = getuid();
    gid = getgid();
    /*
     * We are a login shell if: 1. we were invoked as -<something> and we had
     * no arguments 2. or we were invoked only with the -l flag
     */
    loginsh = (**tempv == '-' && argc == 1) ||
	(argc == 2 && tempv[1][0] == '-' && tempv[1][1] == 'l' &&
	 tempv[1][2] == '\0');

    if (loginsh && **tempv != '-') {
	/*
	 * Mangle the argv space
	 */
	tempv[1][0] = '\0';
	tempv[1][1] = '\0';
	tempv[1] = NULL;
	for (tcp = *tempv; *tcp++;);
	for (tcp--; tcp >= *tempv; tcp--)
	    tcp[1] = tcp[0];
	*++tcp = '-';
	argc--;
    }
    if (loginsh)
	(void) time(&chktim);

    AsciiOnly = 1;
#ifdef NLS
    (void) setlocale(LC_ALL, "");
    {
	int     k;

	for (k = 0200; k <= 0377 && !Isprint(k); k++);
	AsciiOnly = k > 0377;
    }
#else
    AsciiOnly = getenv("LANG") == NULL && getenv("LC_CTYPE") == NULL;
#endif				/* NLS */

    /*
     * 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();
    (void) fclose(cshin);
    (void) fclose(cshout);
    (void) fclose(csherr);
    if (!(cshin  = funopen((void *) &SHIN,  readf, writef, seekf, closef)))
	exit(1);
    if (!(cshout = funopen((void *) &SHOUT, readf, writef, seekf, closef)))
	exit(1);
    if (!(csherr = funopen((void *) &SHERR, readf, writef, seekf, closef)))
	exit(1);
    (void) setvbuf(cshin,  NULL, _IOLBF, 0);
    (void) setvbuf(cshout, NULL, _IOLBF, 0);
    (void) setvbuf(csherr, NULL, _IOLBF, 0);


    /*
     * Initialize the shell variables. ARGV and PROMPT are initialized later.
     * STATUS is also munged in several places. CHILD is munged when
     * forking/waiting
     */
    set(STRstatus, Strsave(STR0));

    if ((tcp = getenv("HOME")) != NULL)
	cp = SAVE(tcp);
    else
	cp = NULL;

    if (cp == NULL)
	fast = 1;		/* No home -> can't read scripts */
    else
	set(STRhome, cp);
    dinit(cp);			/* dinit thinks that HOME == cwd in a login
				 * shell */
    /*
     * Grab other useful things from the environment. Should we grab
     * everything??
     */
    if ((tcp = getenv("LOGNAME")) != NULL ||
	(tcp = getenv("USER")) != NULL)
	set(STRuser, SAVE(tcp));
    if ((tcp = getenv("TERM")) != NULL)
	set(STRterm, SAVE(tcp));

    /*
     * Re-initialize path if set in environment
     */
    if ((tcp = getenv("PATH")) == NULL)
	set1(STRpath, defaultpath(), &shvhed);
    else
	importpath(SAVE(tcp));

    set(STRshell, Strsave(STR_SHELLPATH));

    doldol = putn((int) getpid());	/* For $$ */
    shtemp = Strspl(STRtmpsh, 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, NULL, &osv);
    parintr = (void (*) ()) osv.sv_handler;
    (void) sigvec(SIGTERM, NULL, &osv);
    parterm = (void (*) ()) 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.
     * 
     * We set the first character of our name to be '-' if we are a shell
     * running interruptible commands.  Many programs which examine ps'es 
     * use this to filter such shells out.
     */
    argc--, tempv++;
    while (argc > 0 && (tcp = tempv[0])[0] == '-' && *++tcp != '\0' && !batch) {
	do
	    switch (*tcp++) {

	    case 0:		/* -	Interruptible, no prompt */
		prompt = 0;
		setintr = 1;
		nofile = 1;
		break;

	    case 'b':		/* -b	Next arg is input file */
		batch = 1;
		break;

	    case 'c':		/* -c	Command input from arg */
		if (argc == 1)
		    xexit(0);
		argc--, tempv++;
		arginp = SAVE(tempv[0]);
		prompt = 0;
		nofile = 1;
		break;

	    case 'e':		/* -e	Exit on any error */
		exiterr = 1;
		break;

	    case 'f':		/* -f	Fast start */
		fast = 1;
		break;

	    case 'i':		/* -i	Interactive, even if !intty */
		intact = 1;
		nofile = 1;
		break;

	    case 'm':		/* -m	read .cshrc (from su) */
		mflag = 1;
		break;

	    case 'n':		/* -n	Don't execute */
		noexec = 1;
		break;

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

	    case 's':		/* -s	Read from std input */
		nofile = 1;
		break;

	    case 't':		/* -t	Read one line from input */
		onelflg = 2;
		prompt = 0;
		nofile = 1;
		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(STRverbose);	/* NOW! */
		break;

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

	} while (*tcp);
	tempv++, argc--;
    }

    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 && argc > 0) {
	nofile = open(tempv[0], O_RDONLY);
	if (nofile < 0) {
	    child = 1;		/* So this doesn't return */
	    stderror(ERR_SYSTEM, tempv[0], strerror(errno));
	}
	ffile = SAVE(tempv[0]);
	/* 
	 * Replace FSHIN. Handle /dev/std{in,out,err} specially
	 * since once they are closed we cannot open them again.
	 * In that case we use our own saved descriptors
	 */
	if ((SHIN = dmove(nofile, FSHIN)) < 0) 
	    switch(nofile) {
	    case 0:
		SHIN = FSHIN;
		break;
	    case 1:
		SHIN = FSHOUT;
		break;
	    case 2:
		SHIN = FSHERR;
		break;
	    default:
		stderror(ERR_SYSTEM, tempv[0], strerror(errno));
		break;
	    }
	(void) ioctl(SHIN, FIOCLEX, NULL);
	prompt = 0;
	 /* argc not used any more */ tempv++;
    }

    intty = isatty(SHIN);
    intty |= intact;
    if (intty || (intact && isatty(SHOUT))) {
	if (!batch && (uid != geteuid() || gid != getegid())) {
	    errno = EACCES;
	    child = 1;		/* So this doesn't return */
	    stderror(ERR_SYSTEM, "csh", strerror(errno));
	}
    }
    /*
     * 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;
    settell();
    /*
     * Save the remaining arguments in argv.
     */
    setq(STRargv, blk2short(tempv), &shvhed);

    /*
     * Set up the prompt.
     */
    if (prompt) {
	set(STRprompt, Strsave(uid == 0 ? STRsymhash : STRsymcent));
	/* that's a meta-questionmark */
	set(STRprompt2, Strsave(STRmquestion));
    }

    /*
     * If we are an interactive shell, then start fiddling with the signals;
     * this is a tricky game.
     */
    shpgrp = getpgrp();
    opgrp = tpgrp = -1;
    if (setintr) {
	**argv = '-';
	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(FSHERR))
		f = FSHERR;
	    else if (isatty(FSHOUT))
		f = FSHOUT;
	    else if (isatty(OLDSTD))
		f = OLDSTD;
	    else
		f = -1;
    retry:
	    if ((tpgrp = tcgetpgrp(f)) != -1) {
		if (tpgrp != shpgrp) {
		    sig_t old = signal(SIGTTIN, SIG_DFL);
		    (void) kill(0, SIGTTIN);
		    (void) signal(SIGTTIN, old);
		    goto retry;
		}
		opgrp = shpgrp;
		shpgrp = getpid();
		tpgrp = shpgrp;
		/*
		 * Setpgid will fail if we are a session leader and 
		 * mypid == mypgrp (POSIX 4.3.3)
		 */
		if (opgrp != shpgrp)
		    if (setpgid(0, shpgrp) == -1)
			goto notty;
		/*
		 * We do that after we set our process group, to make sure
		 * that the process group belongs to a process in the same
		 * session as the tty (our process and our group) (POSIX 7.2.4)
		 */
		if (tcsetpgrp(f, shpgrp) == -1)
		    goto notty;
		(void) ioctl(dcopy(f, FSHTTY), FIOCLEX, NULL);
	    }
	    if (tpgrp == -1) {
notty:
		(void) fprintf(csherr, "Warning: no access to tty (%s).\n", 
			       strerror(errno));
		(void) fprintf(csherr, "Thus no job control in this shell.\n");
	    }
	}
    }
    if ((setintr == 0) && (parintr == SIG_DFL))
	setintr = 1;
    (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.
     */
    reenter = setexit();	/* PWP */
    haderr = 0;			/* In case second time through */
    if (!fast && reenter == 0) {
	/* Will have value(STRhome) here because set fast if don't */
	{
	    int     osetintr = setintr;
	    sigset_t omask = sigblock(sigmask(SIGINT));

	    setintr = 0;
#ifdef _PATH_DOTCSHRC
	    (void) srcfile(_PATH_DOTCSHRC, 0, 0);
#endif
	    if (!fast && !arginp && !onelflg)
		dohash(NULL, NULL);
#ifdef _PATH_DOTLOGIN
	    if (loginsh)
		(void) srcfile(_PATH_DOTLOGIN, 0, 0);
#endif
	    (void) sigsetmask(omask);
	    setintr = osetintr;
	}
	(void) srccat(value(STRhome), STRsldotcshrc);

	if (!fast && !arginp && !onelflg && !havhash)
	    dohash(NULL, NULL);
        if (loginsh)
	      (void) srccat(value(STRhome), STRsldotlogin);
	dosource(loadhist, NULL);
    }

    /*
     * Now are ready for the -v and -x flags
     */
    if (nverbose)
	setNS(STRverbose);
    if (nexececho)
	setNS(STRecho);

    /*
     * 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 (intty) {
	if (loginsh) {
	    (void) fprintf(cshout, "logout\n");
	    (void) close(SHIN);
	    child = 1;
	    goodbye();
	}
	else {
	    (void) fprintf(cshout, "exit\n");
	}
    }
    rechist();
    exitstat();
    return (0);
}

void
untty()
{
    if (tpgrp > 0) {
	(void) setpgid(0, opgrp);
	(void) tcsetpgrp(FSHTTY, opgrp);
    }
}

void
importpath(cp)
    Char   *cp;
{
    register int i = 0;
    register Char *dp;
    register Char **pv;
    int     c;

    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 **) xcalloc((size_t) (i + 2), sizeof(Char **));
    dp = cp;
    i = 0;
    if (*dp)
	for (;;) {
	    if ((c = *dp) == ':' || c == 0) {
		*dp = 0;
		pv[i++] = Strsave(*cp ? cp : STRdot);
		if (c) {
		    cp = dp + 1;
		    *dp = ':';
		}
		else
		    break;
	    }
	    dp++;
	}
    pv[i] = 0;
    set1(STRpath, pv, &shvhed);
}

/*
 * Source to the file which is the catenation of the argument names.
 */
static int
srccat(cp, dp)
    Char   *cp, *dp;
{
    register Char *ep = Strspl(cp, dp);
    char   *ptr = short2str(ep);

    xfree((ptr_t) ep);
    return srcfile(ptr, mflag ? 0 : 1, 0);
}

/*
 * Source to a file putting the file descriptor in a safe place (> 2).
 */
static int
srcfile(f, onlyown, flag)
    char   *f;
    bool    onlyown, flag;
{
    register int unit;

    if ((unit = open(f, O_RDONLY)) == -1)
	return 0;
    unit = dmove(unit, -1);

    (void) ioctl(unit, FIOCLEX, NULL);
    srcunit(unit, onlyown, flag);
    return 1;
}

/*
 * 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.
 */
int     insource;
static void
srcunit(unit, onlyown, hflg)
    register int unit;
    bool    onlyown, hflg;
{
    /* We have to push down a lot of state here */
    /* All this could go into a structure */
    int     oSHIN = -1, oldintty = intty, oinsource = insource;
    struct whyle *oldwhyl = whyles;
    Char   *ogointr = gointr, *oarginp = arginp;
    Char   *oevalp = evalp, **oevalvec = evalvec;
    int     oonelflg = onelflg;
    bool    oenterhist = enterhist;
    char    OHIST = HIST;
    bool    otell = cantell;

    struct Bin saveB;
    volatile sigset_t omask;
    jmp_buf oldexit;

    /* The (few) real local variables */
    int     my_reenter;

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

	if (fstat(unit, &stb) < 0) {
	    (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.
     * 
     * We could avoid the critical region by grouping all the stuff in a single
     * structure and pointing at it to move it all at once.  This is less
     * efficient globally on many variable references however.
     */
    insource = 1;
    getexit(oldexit);
    omask = 0;

    if (setintr)
	omask = sigblock(sigmask(SIGINT));
    /* Setup the new values of the state stuff saved above */
    bcopy((char *) &B, (char *) &(saveB), sizeof(B));
    fbuf = NULL;
    fseekp = feobp = fblocks = 0;
    oSHIN = SHIN, SHIN = unit, arginp = 0, onelflg = 0;
    intty = isatty(SHIN), whyles = 0, gointr = 0;
    evalvec = 0;
    evalp = 0;
    enterhist = hflg;
    if (enterhist)
	HIST = '\0';

    /*
     * Now if we are allowing commands to be interrupted, we let ourselves be
     * interrupted.
     */
    if (setintr)
	(void) sigsetmask(omask);
    settell();

    if ((my_reenter = setexit()) == 0)
	process(0);		/* 0 -> blow away on errors */

    if (setintr)
	(void) sigsetmask(omask);
    if (oSHIN >= 0) {
	register int i;

	/* We made it to the new state... free up its storage */
	/* This code could get run twice but xfree doesn't care */
	for (i = 0; i < fblocks; i++)
	    xfree((ptr_t) fbuf[i]);
	xfree((ptr_t) fbuf);

	/* Reset input arena */
	bcopy((char *) &(saveB), (char *) &B, sizeof(B));

	(void) close(SHIN), SHIN = oSHIN;
	arginp = oarginp, onelflg = oonelflg;
	evalp = oevalp, evalvec = oevalvec;
	intty = oldintty, whyles = oldwhyl, gointr = ogointr;
	if (enterhist)
	    HIST = OHIST;
	enterhist = oenterhist;
	cantell = otell;
    }

    resexit(oldexit);
    /*
     * If process reset() (effectively an unwind) then we must also unwind.
     */
    if (my_reenter)
	stderror(ERR_SILENT);
    insource = oinsource;
}

void
rechist()
{
    Char    buf[BUFSIZ];
    int     fp, ftmp, oldidfds;

    if (!fast) {
	if (value(STRsavehist)[0] == '\0')
	    return;
	(void) Strcpy(buf, value(STRhome));
	(void) Strcat(buf, STRsldthist);
	fp = creat(short2str(buf), 0600);
	if (fp == -1)
	    return;
	oldidfds = didfds;
	didfds = 0;
	ftmp = SHOUT;
	SHOUT = fp;
	(void) Strcpy(buf, value(STRsavehist));
	dumphist[2] = buf;
	dohist(dumphist, NULL);
	SHOUT = ftmp;
	(void) close(fp);
	didfds = oldidfds;
    }
}

void
goodbye()
{
    rechist();

    if (loginsh) {
	(void) signal(SIGQUIT, SIG_IGN);
	(void) signal(SIGINT, SIG_IGN);
	(void) signal(SIGTERM, SIG_IGN);
	setintr = 0;		/* No interrupts after "logout" */
	if (!(adrof(STRlogout)))
	    set(STRlogout, STRnormal);
#ifdef _PATH_DOTLOGOUT
	(void) srcfile(_PATH_DOTLOGOUT, 0, 0);
#endif
	if (adrof(STRhome))
	    (void) srccat(value(STRhome), STRsldtlogout);
    }
    exitstat();
}

void
exitstat()
{
    Char *s;
#ifdef PROF
    monitor(0);
#endif
    /*
     * Note that if STATUS is corrupted (i.e. getn bombs) then error will exit
     * directly because we poke child here. Otherwise we might continue
     * unwarrantedly (sic).
     */
    child = 1;
    s = value(STRstatus);
    xexit(s ? getn(s) : 0);
}

/*
 * in the event of a HUP we want to save the history
 */
static void
phup(sig)
int sig;
{
    rechist();
    xexit(sig);
}

Char   *jobargv[2] = {STRjobs, 0};

/*
 * Catch an interrupt, e.g. during lexical input.
 * If we are an interactive shell, we reset the interrupt catch
 * immediately.  In any case we drain the shell output,
 * and finally go through the normal error mechanism, which
 * gets a chance to make the shell go away.
 */
/* ARGSUSED */
void
pintr(notused)
	int notused;
{
    pintr1(1);
}

void
pintr1(wantnl)
    bool    wantnl;
{
    Char **v;
    sigset_t omask;

    omask = sigblock((sigset_t) 0);
    if (setintr) {
	(void) sigsetmask(omask & ~sigmask(SIGINT));
	if (pjobs) {
	    pjobs = 0;
	    (void) fprintf(cshout, "\n");
	    dojobs(jobargv, NULL);
	    stderror(ERR_NAME | ERR_INTR);
	}
    }
    (void) sigsetmask(omask & ~sigmask(SIGCHLD));
    (void) fpurge(cshout);
    (void) endpwent();

    /*
     * If we have an active "onintr" then we search for the label. Note that if
     * one does "onintr -" then we shan't be interruptible so we needn't worry
     * about that here.
     */
    if (gointr) {
	search(T_GOTO, 0, gointr);
	timflg = 0;
	if (v = pargv)
	    pargv = 0, blkfree(v);
	if (v = gargv)
	    gargv = 0, blkfree(v);
	reset();
    }
    else if (intty && wantnl) {
	(void) fputc('\r', cshout);
	(void) fputc('\n', cshout);
    }
    stderror(ERR_SILENT);
}

/*
 * Process is the main driving routine for the shell.
 * It runs all command processing, except for those within { ... }
 * in expressions (which is run by a routine evalav in sh.exp.c which
 * is a stripped down process), and `...` evaluation which is run
 * also by a subset of this code in sh.glob.c in the routine backeval.
 *
 * The code here is a little strange because part of it is interruptible
 * and hence freeing of structures appears to occur when none is necessary
 * if this is ignored.
 *
 * Note that if catch is not set then we will unwind on any error.
 * If an end-of-file occurs, we return.
 */
static struct command *savet = NULL;
void
process(catch)
    bool    catch;
{
    jmp_buf osetexit;
    struct command *t = savet;

    savet = NULL;
    getexit(osetexit);
    for (;;) {
	pendjob();
	paraml.next = paraml.prev = &paraml;
	paraml.word = STRNULL;
	(void) setexit();
	justpr = enterhist;	/* execute if not entering history */

	/*
	 * Interruptible during interactive reads
	 */
	if (setintr)
	    (void) sigsetmask(sigblock((sigset_t) 0) & ~sigmask(SIGINT));

	/*
	 * For the sake of reset()
	 */
	freelex(&paraml);
	if (savet)
	    freesyn(savet), savet = NULL;

	if (haderr) {
	    if (!catch) {
		/* unwind */
		doneinp = 0;
		resexit(osetexit);
		savet = t;
		reset();
	    }
	    haderr = 0;
	    /*
	     * Every error is eventually caught here or the shell dies.  It is
	     * at this point that we clean up any left-over open files, by
	     * closing all but a fixed number of pre-defined files.  Thus
	     * routines don't have to worry about leaving files open due to
	     * deeper errors... they will get closed here.
	     */
	    closem();
	    continue;
	}
	if (doneinp) {
	    doneinp = 0;
	    break;
	}
	if (chkstop)
	    chkstop--;
	if (neednote)
	    pnote();
	if (intty && prompt && evalvec == 0) {
	    mailchk();
	    /*
	     * If we are at the end of the input buffer then we are going to
	     * read fresh stuff. Otherwise, we are rereading input and don't
	     * need or want to prompt.
	     */
	    if (fseekp == feobp)
		printprompt();
	    (void) fflush(cshout);
	}
	if (seterr) {
	    xfree((ptr_t) seterr);
	    seterr = NULL;
	}

	/*
	 * Echo not only on VERBOSE, but also with history expansion. If there
	 * is a lexical error then we forego history echo.
	 */
	if (lex(&paraml) && !seterr && intty || adrof(STRverbose)) {
	    prlex(csherr, &paraml);
	}

	/*
	 * The parser may lose space if interrupted.
	 */
	if (setintr)
	    (void) sigblock(sigmask(SIGINT));

	/*
	 * Save input text on the history list if reading in old history, or it
	 * is from the terminal at the top level and not in a loop.
	 * 
	 * PWP: entry of items in the history list while in a while loop is done
	 * elsewhere...
	 */
	if (enterhist || catch && intty && !whyles)
	    savehist(&paraml);

	/*
	 * Print lexical error messages, except when sourcing history lists.
	 */
	if (!enterhist && seterr)
	    stderror(ERR_OLD);

	/*
	 * If had a history command :p modifier then this is as far as we
	 * should go
	 */
	if (justpr)
	    reset();

	alias(&paraml);

	/*
	 * Parse the words of the input into a parse tree.
	 */
	savet = syntax(paraml.next, &paraml, 0);
	if (seterr)
	    stderror(ERR_OLD);

	execute(savet, (tpgrp > 0 ? tpgrp : -1), NULL, NULL); 

	/*
	 * Made it!
	 */
	freelex(&paraml);
	freesyn((struct command *) savet), savet = NULL;
    }
    resexit(osetexit);
    savet = t;
}

void
/*ARGSUSED*/
dosource(v, t)
    Char **v;
    struct command *t;

{
    register Char *f;
    bool    hflg = 0;
    Char    buf[BUFSIZ];

    v++;
    if (*v && eq(*v, STRmh)) {
	if (*++v == NULL)
	    stderror(ERR_NAME | ERR_HFLAG);
	hflg++;
    }
    (void) Strcpy(buf, *v);
    f = globone(buf, G_ERROR);
    (void) strcpy((char *) buf, short2str(f));
    xfree((ptr_t) f);
    if (!srcfile((char *) buf, 0, hflg) && !hflg)
	stderror(ERR_SYSTEM, (char *) buf, strerror(errno));
}

/*
 * Check for mail.
 * If we are a login shell, then we don't want to tell
 * about any mail file unless its been modified
 * after the time we started.
 * This prevents us from telling the user things he already
 * knows, since the login program insists on saying
 * "You have mail."
 */
static void
mailchk()
{
    register struct varent *v;
    register Char **vp;
    time_t  t;
    int     intvl, cnt;
    struct stat stb;
    bool    new;

    v = adrof(STRmail);
    if (v == 0)
	return;
    (void) time(&t);
    vp = v->vec;
    cnt = blklen(vp);
    intvl = (cnt && number(*vp)) ? (--cnt, getn(*vp++)) : MAILINTVL;
    if (intvl < 1)
	intvl = 1;
    if (chktim + intvl > t)
	return;
    for (; *vp; vp++) {
	if (stat(short2str(*vp), &stb) < 0)
	    continue;
	new = stb.st_mtime > time0.tv_sec;
	if (stb.st_size == 0 || stb.st_atime > stb.st_mtime ||
	    (stb.st_atime < chktim && stb.st_mtime < chktim) ||
	    loginsh && !new)
	    continue;
	if (cnt == 1)
	    (void) fprintf(cshout, "You have %smail.\n", new ? "new " : "");
	else
	    (void) fprintf(cshout, "%s in %s.\n", new ? "New mail" : "Mail", 
			   short2str(*vp));
    }
    chktim = t;
}

/*
 * Extract a home directory from the password file
 * The argument points to a buffer where the name of the
 * user whose home directory is sought is currently.
 * We write the home directory of the user back there.
 */
int
gethdir(home)
    Char   *home;
{
    Char   *h;
    struct passwd *pw;

    /*
     * Is it us?
     */
    if (*home == '\0') {
	if (h = value(STRhome)) {
	    (void) Strcpy(home, h);
	    return 0;
	}
	else
	    return 1;
    }

    if (pw = getpwnam(short2str(home))) {
	(void) Strcpy(home, str2short(pw->pw_dir));
	return 0;
    }
    else
	return 1;
}

/*
 * When didfds is set, we do I/O from 0, 1, 2 otherwise from 15, 16, 17
 * We alsocheck if the shell has already chenged the decriptor to point to
 * 0, 1, 2 when didfds is set.
 */
#define DESC(a) (*((int *) (a)) - (didfds && *((int *) a) >= FSHIN ? FSHIN : 0))

static int
readf(oreo, buf, siz)
    void *oreo;
    char *buf;
    int siz;
{
    return read(DESC(oreo), buf, siz);
}


static int
writef(oreo, buf, siz)
    void *oreo;
    const char *buf;
    int siz;
{
    return write(DESC(oreo), buf, siz);
}

static fpos_t
seekf(oreo, off, whence)
    void *oreo;
    fpos_t off;
    int whence;
{
    return lseek(DESC(oreo), off, whence);
}


static int
closef(oreo)
    void *oreo;
{
    return close(DESC(oreo));
}


/*
 * Move the initial descriptors to their eventual
 * resting places, closin all other units.
 */
void
initdesc()
{

    didfds = 0;			/* 0, 1, 2 aren't set up */
    (void) ioctl(SHIN = dcopy(0, FSHIN), FIOCLEX, NULL);
    (void) ioctl(SHOUT = dcopy(1, FSHOUT), FIOCLEX, NULL);
    (void) ioctl(SHERR = dcopy(2, FSHERR), FIOCLEX, NULL);
    (void) ioctl(OLDSTD = dcopy(SHIN, FOLDSTD), FIOCLEX, NULL);
    closem();
}


void
#ifdef PROF
done(i)
#else
xexit(i)
#endif
    int     i;
{
    untty();
    _exit(i);
}

static Char **
defaultpath()
{
    char   *ptr;
    Char  **blk, **blkp;
    struct stat stb;

    blkp = blk = (Char **) xmalloc((size_t) sizeof(Char *) * 10);

#define DIRAPPEND(a)  \
	if (stat(ptr = a, &stb) == 0 && (stb.st_mode & S_IFMT) == S_IFDIR) \
		*blkp++ = SAVE(ptr)

    DIRAPPEND(_PATH_BIN);
    DIRAPPEND(_PATH_USRBIN);

#undef DIRAPPEND

    *blkp++ = Strsave(STRdot);
    *blkp = NULL;
    return (blk);
}

void
printprompt()
{
    register Char *cp;

    if (!whyles) {
	for (cp = value(STRprompt); *cp; cp++)
	    if (*cp == HIST)
		(void) fprintf(cshout, "%d", eventno + 1);
	    else {
		if (*cp == '\\' && cp[1] == HIST)
		    cp++;
		(void) fputc(*cp | QUOTE, cshout);
	    }
    }
    else
	/*
	 * Prompt for forward reading loop body content.
	 */
	(void) fprintf(cshout, "? ");
    (void) fflush(cshout);
}