xref: /netbsd/src/bin/csh/csh.c

/* $NetBSD: csh.c,v 1.56 2022/09/15 11:35:06 martin Exp $ */

/*-
 * Copyright (c) 1980, 1991, 1993
 *        The Regents of the University of California.  All rights reserved.
 *
 * 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. 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.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1980, 1991, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)csh.c       8.2 (Berkeley) 10/12/93";
#else
__RCSID("$NetBSD: csh.c,v 1.56 2022/09/15 11:35:06 martin Exp $");
#endif
#endif /* not lint */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>

#include <errno.h>
#include <fcntl.h>
#include <locale.h>
#include <paths.h>  /* should this be included in pathnames.h instead? */
#include <pwd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <vis.h>

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

/*
 * 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
 */

FILE *cshin, *cshout, *csherr;
struct timespec time0;
struct rusage ru0;
struct varent shvhed, aliases;
Char HISTSUB;
int editing;

int child;
int chkstop;
int didfds;
int doneinp;
int exiterr;
int haderr;
int havhash;
int intact;
int intty;
int justpr;
int loginsh;
int neednote;
int noexec;
int pjobs;
int setintr;
int timflg;

Char *arginp;
Char *ffile;
int onelflg;
Char *shtemp;

time_t chktim;
Char *doldol;
pid_t backpid;
gid_t egid, gid;
uid_t euid, uid;
int shpgrp;
int tpgrp;

int opgrp;

int SHIN;
int SHOUT;
int SHERR;
int OLDSTD;

jmp_buf reslab;

Char *gointr;

sig_t parintr;
sig_t parterm;

struct Bin B;

struct Ain lineloc;
int cantell;
Char *lap;
struct whyle *whyles;

struct wordent *alhistp,*alhistt;

int AsciiOnly;
int gflag;
long pnleft;
Char *pargs;
Char *pargcp;
struct Hist Histlist;
struct wordent paraml;
int eventno;
int lastev;
Char HIST;
Char HISTSUB;
const char *bname;
Char *Vsav;
Char *Vdp;
Char *Vexpath;
char **Vt;
Char **evalvec;
Char *evalp;
Char *word_chars;
Char *STR_SHELLPATH;
#ifdef _PATH_BSHELL
Char *STR_BSHELL;
#endif
Char *STR_WORD_CHARS;
Char **STR_environ;
#ifdef EDIT
EditLine *el;
History *hi;
#endif
int editing;

Char *dumphist[] = {STRhistory, STRmh, 0, 0};
Char *tildehist[] = {STRsource, STRmh, STRtildothist, 0};

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

extern char **environ;

static ssize_t readf(void *, void *, size_t);
static off_t seekf(void *, off_t, int);
static ssize_t writef(void *, const void *, size_t);
static int closef(void *);
static int srccat(Char *, Char *);
static int srcfile(const char *, int, int);
__dead static void phup(int);
static void srcunit(int, int, int);
static void mailchk(void);
#ifndef _PATH_DEFPATH
static Char **defaultpath(void);
#endif

int
main(int argc, char *argv[])
{
    struct sigaction oact;
    Char *cp;
    char *tcp, **tempv;
    const char *ecp;
    sigset_t nsigset;
    int f;

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

    setprogname(argv[0]);
    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();
    euid = geteuid();
    egid = getegid();
    /*
     * 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++;)
              continue;
          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++)
              continue;
          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();
    /*
     * XXX: This is to keep programs that use stdio happy.
     *        what we really want is freunopen() ....
     *        Closing cshin cshout and csherr (which are really stdin stdout
     *        and stderr at this point and then reopening them in the same order
     *        gives us again stdin == cshin stdout == cshout and stderr == csherr.
     *        If that was not the case builtins like printf that use stdio
     *        would break. But in any case we could fix that with memcpy and
     *        a bit of pointer manipulation...
     *        Fortunately this is not needed under the current implementation
     *        of stdio.
     */
    (void)fclose(cshin);
    (void)fclose(cshout);
    (void)fclose(csherr);
    if (!(cshin  = funopen2((void *) &SHIN,  readf, writef, seekf, NULL,
          closef)))
          exit(1);
    if (!(cshout = funopen2((void *) &SHOUT, readf, writef, seekf, NULL,
          closef)))
          exit(1);
    if (!(csherr = funopen2((void *) &SHERR, readf, writef, seekf, NULL,
          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 ((ecp = getenv("HOME")) != NULL)
          cp = quote(SAVE(ecp));
    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 ((ecp = getenv("LOGNAME")) != NULL ||
          (ecp = getenv("USER")) != NULL)
          set(STRuser, quote(SAVE(ecp)));
    if ((ecp = getenv("TERM")) != NULL)
          set(STRterm, quote(SAVE(ecp)));

    /*
     * Re-initialize path if set in environment
     */
    if ((ecp = getenv("PATH")) == NULL) {
#ifdef _PATH_DEFPATH
          importpath(str2short(_PATH_DEFPATH));
#else
          setq(STRpath, defaultpath(), &shvhed);
#endif
    } else {
          importpath(str2short(ecp));
    }

    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)sigaction(SIGINT, NULL, &oact);
    parintr = oact.sa_handler;
    (void)sigaction(SIGTERM, NULL, &oact);
    parterm = oact.sa_handler;

    /* catch these all, login shell or not */
    (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));
                    /* NOTREACHED */
              }
          (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 != euid || gid != egid)) {
              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);
          sigemptyset(&nsigset);
          (void)sigaddset(&nsigset, SIGINT);
          (void)sigprocmask(SIG_BLOCK, &nsigset, NULL);
          (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 */
          {
              sig_t oparintr;
              sigset_t osigset;
              int osetintr;

              oparintr = parintr;
              osetintr = setintr;
              sigemptyset(&nsigset);
              (void)sigaddset(&nsigset, SIGINT);
              (void)sigprocmask(SIG_BLOCK, &nsigset, &osigset);

              setintr = 0;
              parintr = SIG_IGN;        /* Disable onintr */
#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)sigprocmask(SIG_SETMASK, &osigset, NULL);
              setintr = osetintr;
              parintr = oparintr;
          }
          (void)srccat(value(STRhome), STRsldotcshrc);

          if (!fast && !arginp && !onelflg && !havhash)
              dohash(NULL, NULL);
          /*
           * Source history before .login so that it is available in .login
           */
          if ((cp = value(STRhistfile)) != STRNULL)
              tildehist[2] = cp;
          dosource(tildehist, NULL);
        if (loginsh)
                (void)srccat(value(STRhome), STRsldotlogin);
    }

    /*
     * 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();
    /* NOTREACHED */
}

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

void
importpath(Char *cp)
{
    Char *dp, **pv;
    int c, i;

    i = 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 = xcalloc((size_t) (i + 2), sizeof(*pv));
    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;
    setq(STRpath, pv, &shvhed);
}

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

    ep = Strspl(cp, dp);
    ptr = short2str(ep);
    free(ep);
    return srcfile(ptr, mflag ? 0 : 1, 0);
}

/*
 * Source to a file putting the file descriptor in a safe place (> 2).
 */
static int
srcfile(const char *f, int onlyown, int flag)
{
    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(int unit, int onlyown, int hflg)
{
    /* We have to push down a lot of state here */
    /* All this could go into a structure */
    struct whyle *oldwhyl;
    struct Bin saveB;
    sigset_t nsigset, osigset;
    jmp_buf oldexit;
    Char *oarginp, *oevalp, **oevalvec, *ogointr;
    Char OHIST;
    int oSHIN, oinsource, oldintty, oonelflg;
    int oenterhist, otell;
    /* The (few) real local variables */
    int my_reenter;

    oSHIN = -1;
    oldintty = intty;
    oinsource = insource;
    oldwhyl = whyles;
    ogointr = gointr;
    oarginp = arginp;
    oevalp = evalp;
    oevalvec = evalvec;
    oonelflg = onelflg;
    oenterhist = enterhist;
    OHIST = HIST;
    otell = cantell;

    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);

    if (setintr) {
          sigemptyset(&nsigset);
          (void)sigaddset(&nsigset, SIGINT);
          (void)sigprocmask(SIG_BLOCK, &nsigset, &osigset);
    }
    /* Setup the new values of the state stuff saved above */
    (void)memcpy(&saveB, &B, 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)sigprocmask(SIG_SETMASK, &osigset, NULL);
    settell();

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

    if (setintr)
          (void)sigprocmask(SIG_SETMASK, &osigset, NULL);
    if (oSHIN >= 0) {
          int i;

          /* We made it to the new state... free up its storage */
          for (i = 0; i < fblocks; i++)
              free(fbuf[i]);
          free(fbuf);

          /* Reset input arena */
          /* (note that this clears fbuf and fblocks) */
          (void)memcpy(&B, &saveB, 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(void)
{
    Char buf[BUFSIZE], hbuf[BUFSIZE], *hfile;
    int fp, ftmp, oldidfds;
    struct varent *shist;

    if (!fast) {
          /*
           * If $savehist is just set, we use the value of $history
           * else we use the value in $savehist
           */
          if ((shist = adrof(STRsavehist)) != NULL) {
              if (shist->vec[0][0] != '\0')
                    (void)Strcpy(hbuf, shist->vec[0]);
              else if ((shist = adrof(STRhistory)) && shist->vec[0][0] != '\0')
                    (void)Strcpy(hbuf, shist->vec[0]);
              else
                    return;
          }
          else
              return;

          if ((hfile = value(STRhistfile)) == STRNULL) {
              hfile = Strcpy(buf, value(STRhome));
              (void) Strcat(buf, STRsldthist);
          }

          if ((fp = open(short2str(hfile), O_WRONLY | O_CREAT | O_TRUNC,
              0600)) == -1)
              return;

          oldidfds = didfds;
          didfds = 0;
          ftmp = SHOUT;
          SHOUT = fp;
          dumphist[2] = hbuf;
          dohist(dumphist, NULL);
          SHOUT = ftmp;
          (void)close(fp);
          didfds = oldidfds;
    }
}

void
goodbye(void)
{
    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();
    /* NOTREACHED */
}

__dead void
exitstat(void)
{
    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);
    /* NOTREACHED */
}

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

    /*
     * We kill the last foreground process group. It then becomes
     * responsible to propagate the SIGHUP to its progeny.
     */
    {
          struct process *pp, *np;

          for (pp = proclist.p_next; pp; pp = pp->p_next) {
              np = pp;
              /*
               * Find if this job is in the foreground. It could be that
               * the process leader has exited and the foreground flag
               * is cleared for it.
               */
              do
                    /*
                     * If a process is in the foreground; we try to kill
                     * its process group. If we succeed, then the
                     * whole job is gone. Otherwise we keep going...
                     * But avoid sending HUP to the shell again.
                     */
                    if ((np->p_flags & PFOREGND) != 0 && np->p_jobid != shpgrp &&
                        kill(-np->p_jobid, SIGHUP) != -1) {
                        /* In case the job was suspended... */
                        (void)kill(-np->p_jobid, SIGCONT);
                        break;
                    }
              while ((np = np->p_friends) != pp);
          }
    }
    xexit(sig);
    /* NOTREACHED */
}

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(int notused)
{
    pintr1(1);
    /* NOTREACHED */
}

void
pintr1(int wantnl)
{
    Char **v;
    sigset_t nsigset, osigset;

    sigemptyset(&nsigset);
    (void)sigprocmask(SIG_BLOCK, &nsigset, &osigset);
    if (setintr) {
          nsigset = osigset;
          (void)sigdelset(&nsigset, SIGINT);
          (void)sigprocmask(SIG_SETMASK, &nsigset, NULL);
          if (pjobs) {
              pjobs = 0;
              (void)fprintf(cshout, "\n");
              dojobs(jobargv, NULL);
              stderror(ERR_NAME | ERR_INTR);
          }
    }
    (void)sigdelset(&osigset, SIGCHLD);
    (void)sigprocmask(SIG_SETMASK, &osigset, NULL);
    (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) {
          gotolab(gointr);
          timflg = 0;
          if ((v = pargv) != NULL)
              pargv = 0, blkfree(v);
          if ((v = gargv) != NULL)
              gargv = 0, blkfree(v);
          reset();
    }
    else if (intty && wantnl) {
          (void)fputc('\r', cshout);
          (void)fputc('\n', cshout);
    }
    stderror(ERR_SILENT);
    /* NOTREACHED */
}

/*
 * 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(int catch)
{
    struct command *t;
    jmp_buf osetexit;
    sigset_t nsigset;

    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) {
              sigemptyset(&nsigset);
              (void)sigaddset(&nsigset, SIGINT);
              (void)sigprocmask(SIG_UNBLOCK, &nsigset, NULL);
          }

          /*
           * 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();
#ifdef EDIT
              updateediting();
#endif
              /*
               * 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 (aret == F_SEEK && fseekp == feobp)
                    printprompt();
              (void)fflush(cshout);
          }
          if (seterr) {
              free(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)) {
              int odidfds = didfds;
              fflush(csherr);
              didfds = 0;
              prlex(csherr, &paraml);
              fflush(csherr);
              didfds = odidfds;
          }

          /*
           * The parser may lose space if interrupted.
           */
          if (setintr)
              (void)sigprocmask(SIG_BLOCK, &nsigset, NULL);

          /*
           * 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(savet), savet = NULL;
    }
    resexit(osetexit);
    savet = t;
}

void
/*ARGSUSED*/
dosource(Char **v, struct command *t)
{
    Char buf[BUFSIZE], *f;
    int hflg;

    hflg = 0;
    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));
    free(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(void)
{
    struct stat stb;
    struct varent *v;
    Char **vp;
    time_t t;
    int cnt, intvl;
    int 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",
                                 vis_str(*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(Char *home)
{
    struct passwd *pw;
    Char *h;

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

    if ((pw = getpwnam(short2str(home))) != NULL) {
          (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 also check if the shell has already changed the descriptor to point to
 * 0, 1, 2 when didfds is set.
 */
#define DESC(a) (*((int *) (a)) - (didfds && *((int *) a) >= FSHIN ? FSHIN : 0))

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


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

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


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


/*
 * Print the visible version of a string.
 */
int
vis_fputc(int ch, FILE *fp)
{
    char uenc[5];   /* 4 + NULL */

    if (ch & QUOTE)
          return fputc(ch & TRIM, fp);
    /*
     * XXX: When we are in AsciiOnly we want all characters >= 0200 to
     * be encoded, but currently there is no way in vis to do that.
     */
    (void)vis(uenc, ch & TRIM, VIS_NOSLASH, 0);
    return (fputs(uenc, fp));
}

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


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

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

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

#define DIRAPPEND(a)  \
          if (stat(ptr = a, &stb) == 0 && S_ISDIR(stb.st_mode)) \
                    *blkp++ = SAVE(ptr)
#ifdef RESCUEDIR
    DIRAPPEND(RESCUEDIR);
#endif
    DIRAPPEND(_PATH_BIN);
    DIRAPPEND(_PATH_USRBIN);

#undef DIRAPPEND

#if 0
    if (euid != 0 && uid != 0)
          *blkp++ = Strsave(STRdot);
#endif

    *blkp = NULL;
    return (blk);
}
#endif /* _PATH_DEFPATH */

void
printprompt(void)
{
    Char *cp;

    if (editing)
          return;

    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)vis_fputc(*cp | QUOTE, cshout);
              }
    }
    else
          /*
           * Prompt for forward reading loop body content.
           */
          (void)fprintf(cshout, "? ");
    (void)fflush(cshout);
}

#ifdef EDIT
char *
printpromptstr(EditLine *elx) {
    static char pbuf[1024];
    static char qspace[] = "? ";
    Char *cp;
    size_t i;

    if (whyles)
          return qspace;

    i = 0;
    for (cp = value(STRprompt); *cp; cp++) {
          if (i >= sizeof(pbuf))
              break;
          if (*cp == HIST) {
              int r;
              r = snprintf(pbuf + i, sizeof(pbuf) - i, "%d", eventno + 1);
              if (r > 0)
                    i += (size_t)r;
          } else
              pbuf[i++] = (char)*cp;
    }
    if (i >= sizeof(pbuf))
          i = sizeof(pbuf) - 1;
    pbuf[i] = '\0';
    return pbuf;
}
#endif