/*
 * $Id: proc.c,v 1.6 2002/08/23 13:41:37 howardjp Exp $
 *
 * Copyright (c) 1990
 *      Jan Wolter.  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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Jan Wolter
 *      and his contributors.
 * 4. Neither the name of Jan Wolter nor the names of his contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JAN WOLTER 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 JAN WOLTER 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.
 */

/* PARTY PROGRAM -- FILTER MANAGEMENT AND SIMILAR TRICKY STUFF -- Jan Wolter */

#include "party.h"
#include "opt.h"

int out_fd = 1;		/* File descriptor of terminal or external filter */
char ofilter[BFSZ];	/* Command line of current filter */

/* START_FILTER:  Start up the external filter named by the filter option.
 * If some different filter is already running, we kill it first.
 */

start_filter()
{
FILE *out_fp;

        /* If a filter is running, and it is different, kill it */
        if (out_fd != 1)
        {
		if (!strncmp(ofilter,opt[OPT_FILTER].str, BFSZ))
                        return(0);
                else
                        stop_filter();
        }

        if ((out_fp = upopen(opt[OPT_FILTER].str,"w")) == NULL)
        {
                err("cannot execute filter: %s\n",ofilter);
                opt[OPT_FILTER].yes = 0;
                return;
        }
        out_fd = fileno(out_fp);
        strcpy(ofilter,opt[OPT_FILTER].str);
}

/* STOP_FILTER:  This shuts down any output filter currently running in
 * a nice manner (by closing it's input stream), and resets output direct
 * to the terminal.  This is the normal method of shutting down a filter.
 */

stop_filter()
{
        if (out_fd == 1)
                return;
        upclose();
        out_fd= 1;
}

/* KILL_FILTER:  This shuts down any output filter currently running in
 * a nasty manner (by killing the process), and resets output direct
 * to the terminal.  This is done when party was terminated by an interrupt
 * or a hangup.
 */

kill_filter()
{
        if (out_fd == 1)
                return;
        upkill();
        out_fd= 1;
}


/* UPOPEN/UPCLOSE/UPKILL - Run command on a pipe
 *
 *    This is similar to the Unix popen() and pclose() calls, except
 *      (1)     upopen() runs the command with the original user id.
 *      (2)     upopen() shuts off interrupts in the child process.
 *      (2)     upopen() closes the last upopen() whenever it is called.
 *      (3)     upclose() closes the last upopen(), and takes no args.
 *    upkill() just murders the child process and returns.
 */

FILE *f_lastpop = NULL;		/* current upopened stream  (NULL means none) */
int p_lastpop;			/* process id of last upopened command */

FILE *upopen(cmd,mode)
char *cmd;
char *mode;
{
int pip[2];
register int chd_pipe,par_pipe;
FILE *fdopen();
#ifdef NODUP2
int t;
#endif /*NODUP2*/

        if (f_lastpop) upclose();

        /* Make a pipe */
        if (pipe(pip)) return((FILE *)0);

        /* Choose ends */
        par_pipe= (*mode == 'r') ? pip[0] : pip[1];
        chd_pipe= (*mode == 'r') ? pip[1] : pip[0];

        switch (p_lastpop= fork())
        {
        case 0:
                /* Child - run command */
                signal(SIGINT,SIG_IGN);
                signal(SIGQUIT,SIG_IGN);
                close(par_pipe);
                if (chd_pipe != (*mode == 'r'?1:0))
                {
#ifdef NODUP2
                        close(t = (*mode == 'r'?1:0));
                        if (fcntl(chd_pipe,F_DUPFD,t) != t)
                        {
                                printf("Panic: can dup pipe\n");
                                exit(1);
                        }
#else
                        dup2(chd_pipe,(*mode == 'r'?1:0));
#endif /*NODUP2*/
                        close(chd_pipe);
                }
                setuid(getuid());
                setgid(getgid());
                execcmd(cmd);
                exit(-1);
        case -1:
                close(chd_pipe);
                close(par_pipe);
                return((FILE *)0);
        default:
                close(chd_pipe);
                return(f_lastpop=fdopen(par_pipe,mode));
        }
}

upclose()
{
int pid;
        if (f_lastpop == NULL || fclose(f_lastpop)) return;

        f_lastpop=NULL;
        while ((pid=wait((int *)0)) != -1 && pid != p_lastpop )
                ;
}

upkill()
{
        if (f_lastpop != NULL)
                kill(p_lastpop,SIGTERM);
}

/* PRINTEXEC: Print the given string, unless the first characters is a !
 * in which case we exec it.
 */

printexec(fp,str)
FILE *fp;
char *str;
{
	if (*str == '!')
		usystem(str+1);
	else if (*str == '/')
		help(str,1);
	else
		fprintf(fp,"%s\n",str);
}

/* USYSTEM:  A modified version of the system() command that resets the uid
 * and the gid to the user before executing the subcommand.  If the command
 * doesn't appear to include any special characters, it will exec the
 * command directly instead of starting a shell to parse it.
 */

usystem(cmd)
char *cmd;
{
register int cpid,wpid;
vint (*old_intr)(), (*old_quit)();

	if (debug) db("usystem: %s\n",cmd);

        if ((cpid = fork()) == 0)
        {
            dup2(2,1);
            setuid(getuid());
            setgid(getgid());
	    signal(SIGPIPE,oldsigpipe);
            execcmd(cmd);
            exit(-1);
        }
        old_intr = signal(SIGINT,SIG_IGN);
        old_quit = signal(SIGQUIT,SIG_IGN);
        while ((wpid = wait((int *)0)) != cpid && wpid != -1)
            ;
        signal(SIGINT,old_intr);
        signal(SIGQUIT,old_quit);

	if (debug) db("usystem done\n");
}

execcmd(cmd)
char *cmd;
{
char *cmdv[200];
char *cp;
int i,j;

        /* If there are no fancy characters in it, parse it ourselves */
        if (opt[OPT_FASTSHELL].yes &&
	    strpbrk(cmd,"<>*?|![]{}~`$&';\\\"") == NULL)
        {
                /* Skip leading spaces */
		cp= firstout(cmd," \t");
                cmdv[i=0] = cp;

                /* Break up args at the spaces */
                while (*(cp= firstin(cp," \t")) != '\0')
                {
			*(cp++) = '\0';
			cp= firstout(cp," \t");
			if (*cp != '\0')
				cmdv[++i] = cp;
                }

                /* Ignore Null command */
                if (cmdv[0] == cp) return;
                cmdv[i+1] = NULL;

                execvp(cmdv[0],cmdv);
                fprintf(stderr,"%s: cannot execute %s\n",progname,cmdv[0]);
        }
        else
        {
                execl(opt[OPT_SHELL].str,leafname(opt[OPT_SHELL].str),"-c",
                        cmd,(char *)NULL);
                fprintf(stderr,"%s: cannot execute shell %s\n",
                        progname,opt[OPT_SHELL].str);
        }
}