/*      $NetBSD: main.c,v 1.90 2023/04/07 10:34:13 kre Exp $    */

/*-
 * Copyright (c) 1991, 1993
 *      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. 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) 1991, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)main.c      8.7 (Berkeley) 7/19/95";
#else
__RCSID("$NetBSD: main.c,v 1.90 2023/04/07 10:34:13 kre Exp $");
#endif
#endif /* not lint */

#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdbool.h>
#include <stdlib.h>
#include <locale.h>
#include <fcntl.h>


#include "shell.h"
#include "main.h"
#include "mail.h"
#include "options.h"
#include "builtins.h"
#include "output.h"
#include "parser.h"
#include "nodes.h"
#include "expand.h"
#include "eval.h"
#include "jobs.h"
#include "input.h"
#include "trap.h"
#include "var.h"
#include "show.h"
#include "memalloc.h"
#include "error.h"
#include "init.h"
#include "mystring.h"
#include "exec.h"
#include "cd.h"
#include "redir.h"

#define PROFILE 0

int rootpid;
int rootshell;
struct jmploc main_handler;
int max_user_fd;
long user_fd_limit;
bool privileged;
#if PROFILE
short profile_buf[16384];
extern int etext();
#endif

STATIC void read_profile(const char *);

/*
 * 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.
 */

int
main(int argc, char **argv)
{
        struct stackmark smark;
        volatile int state;
        char *shinit;
        uid_t uid;
        gid_t gid;
        sigset_t mask;
        bool waspriv;

        /*
         * If we happen to be invoked with SIGCHLD ignored, we cannot
         * successfully do almost anything.   Perhaps we should remember
         * its state and pass it on ignored to children if it was ignored
         * on entry, but that seems like just leaving the shit on the
         * footpath for someone else to fall into...
         */
        (void)signal(SIGCHLD, SIG_DFL);
        /*
         * Similarly, SIGCHLD must not be blocked
         */
        sigemptyset(&mask);
        sigaddset(&mask, SIGCHLD);
        sigprocmask(SIG_UNBLOCK, &mask, NULL);

        uid = getuid();
        gid = getgid();

        waspriv = privileged = (uid != geteuid()) || (gid != getegid());

        max_user_fd = fcntl(0, F_MAXFD);
        if (max_user_fd < 2)
                max_user_fd = 2;
        user_fd_limit = sysconf(_SC_OPEN_MAX);

        setlocale(LC_ALL, "");

        posix = getenv("POSIXLY_CORRECT") != NULL;
#if PROFILE
        monitor(4, etext, profile_buf, sizeof profile_buf, 50);
#endif
        state = 0;
        if (setjmp(main_handler.loc)) {
                /*
                 * When a shell procedure is executed, we raise the
                 * exception EXSHELLPROC to clean up before executing
                 * the shell procedure.
                 */
                switch (exception) {
                case EXSHELLPROC:
                        rootpid = getpid();
                        rootshell = 1;
                        minusc = NULL;
                        state = 3;
                        break;

                case EXEXEC:
                        exitstatus = exerrno;
                        break;

                case EXERROR:
                        exitstatus = 2;
                        break;

                default:
                        break;
                }

                if (exception != EXSHELLPROC) {
                        if (state == 0 || iflag == 0 || ! rootshell ||
                            exception == EXEXIT)
                                exitshell(exitstatus);
                }
                reset();
                if (exception == EXINT) {
                        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 = &main_handler;
#ifdef DEBUG
#if DEBUG >= 2
        debug = 1;      /* this may be reset by procargs() later */
#endif
        opentrace();
        if (privileged)
                trputs("Privileged ");
        trputs("Shell args:  ");  trargs(argv);
#if DEBUG >= 3
        set_debug(((DEBUG)==3 ? "_@" : "++"), 1);
#endif
#endif
        rootpid = getpid();
        rootshell = 1;
        init();
        initpwd();
        setstackmark(&smark);
        procargs(argc, argv);
        setvar_invocation(argc, argv);

#if 0   /* This now happens (indirectly) in the procargs() just above */
        /*
         * Limit bogus system(3) or popen(3) calls in setuid binaries,
         * by requiring the -p flag
         */
        if (!pflag && (uid != geteuid() || gid != getegid())) {
                setuid(uid);
                setgid(gid);
                /* PS1 might need to be changed accordingly. */
                choose_ps1();
        }
#else   /* except for this one little bit */
        if (waspriv && !privileged)
                choose_ps1();
#endif

        if (loginsh) {
                state = 1;
                read_profile("/etc/profile");
 state1:
                state = 2;
                if (!privileged) {
                        char *profile;
                        const char *home;

                        home = lookupvar("HOME");
                        if (home == NULL)
                                home = nullstr;
                        profile = ststrcat(NULL, home, "/.profile", STSTRC_END);
                        read_profile(profile);
                        stunalloc(profile);
                }
#if 0   /* FreeBSD does (effectively) ...*/
                else
                        read_profile("/etc/suid_profile");
#endif
        }
 state2:
        state = 3;
        if ((iflag || !posix) && !privileged) {
                struct stackmark env_smark;

                setstackmark(&env_smark);
                if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') {
                        state = 3;
                        read_profile(expandenv(shinit));
                }
                popstackmark(&env_smark);
        }
 state3:
        state = 4;
        line_number = 1;        /* undo anything from profile files */

        if (sflag == 0 || minusc) {
                static int sigs[] =  {
                    SIGINT, SIGQUIT, SIGHUP,
#ifdef SIGTSTP
                    SIGTSTP,
#endif
                    SIGPIPE
                };
#define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0]))
                size_t i;

                for (i = 0; i < SIGSSIZE; i++)
                    setsignal(sigs[i], 0);
        }

        rststackmark(&smark);   /* this one is never popped */

        if (minusc)
                evalstring(minusc, sflag ? 0 : EV_EXIT);

        if (sflag || minusc == NULL) {
 state4:        /* XXX ??? - why isn't this before the "if" statement */
                cmdloop(1);
                if (iflag) {
                        out2str("\n");
                        flushout(&errout);
                }
        }
#if PROFILE
        monitor(0);
#endif
        line_number = plinno;
        exitshell(exitstatus);
        /* NOTREACHED */
}


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

void
cmdloop(int top)
{
        union node *n;
        struct stackmark smark;
        int inter;
        int numeof = 0;
        enum skipstate skip;

        CTRACE(DBG_ALWAYS, ("cmdloop(%d) called\n", top));
        setstackmark(&smark);
        for (;;) {
                if (pendingsigs)
                        dotrap();
                inter = 0;
                if (iflag == 1 && top) {
                        inter = 1;
                        showjobs(out2, SHOW_CHANGED);
                        chkmail(0);
                        flushout(&errout);
                        nflag = 0;
                }
                n = parsecmd(inter);
                VXTRACE(DBG_PARSE|DBG_EVAL|DBG_CMDS,("cmdloop: "),showtree(n));
                if (n == NEOF) {
                        if (!top || numeof >= 50)
                                break;
                        if (nflag)
                                break;
                        if (!stoppedjobs()) {
                                if (!iflag || !Iflag)
                                        break;
                                out2str("\nUse \"exit\" to leave shell.\n");
                        }
                        numeof++;
                } else if (n != NULL && nflag == 0) {
                        job_warning = (job_warning == 2) ? 1 : 0;
                        numeof = 0;
                        evaltree(n, 0);
                }
                rststackmark(&smark);

                /*
                 * Any SKIP* can occur here!  SKIP(FUNC|BREAK|CONT) occur when
                 * a dotcmd is in a loop or a function body and appropriate
                 * built-ins occurs in file scope in the sourced file.  Values
                 * other than SKIPFILE are reset by the appropriate eval*()
                 * that contained the dotcmd() call.
                 */
                skip = current_skipstate();
                if (skip != SKIPNONE) {
                        if (skip == SKIPFILE)
                                stop_skipping();
                        break;
                }
        }
        popstackmark(&smark);
}



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

STATIC void
read_profile(const char *name)
{
        int fd;
        int xflag_set = 0;
        int vflag_set = 0;

        if (*name == '\0')
                return;

        INTOFF;
        if ((fd = open(name, O_RDONLY)) >= 0)
                setinputfd(fd, 1);
        INTON;
        if (fd < 0)
                return;
        /* -q turns off -x and -v just when executing init files */
        if (qflag)  {
            if (xflag)
                    xflag = 0, xflag_set = 1;
            if (vflag)
                    vflag = 0, vflag_set = 1;
        }
        (void)set_dot_funcnest(1);      /* allow profile to "return" */
        cmdloop(0);
        (void)set_dot_funcnest(0);
        if (qflag)  {
            if (xflag_set)
                    xflag = 1;
            if (vflag_set)
                    vflag = 1;
        }
        popfile();
}



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

void
readcmdfile(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();
}



int
exitcmd(int argc, char **argv)
{
        if (stoppedjobs())
                return 0;
        if (argc > 1)
                exitshell(number(argv[1]));
        else
                exitshell_savedstatus();
        /* NOTREACHED */
}