usr/src/usr.bin/mail/popen.c

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#ifdef notdef
static char sccsid[] = "@(#)popen.c     5.8 (Berkeley) %G%";
#endif /* notdef */

#include "rcv.h"
#include <stdio.h>
#include <sys/signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <errno.h>

#define tst(a,b)        (*mode == 'r'? (b) : (a))
#define RDR     0
#define WTR     1
static  int     popen_pid[20];

FILE *
Popen(cmd,mode)
char    *cmd;
char    *mode;
{
        int p[2];
        register int myside, hisside;
        int pid;
        char *argv[MAXARGC];

        if (pipe(p) < 0)
                return NULL;
        myside = tst(p[WTR], p[RDR]);
        hisside = tst(p[RDR], p[WTR]);
        if ((pid = vfork()) == 0) {
                /* myside and hisside reverse roles in child */
                close(myside);
                dup2(hisside, tst(0, 1));
                close(hisside);
                (void) getrawlist(cmd, argv, MAXARGC);
                execvp(argv[0], argv);
                fprintf(stderr, "Cannot execute %s\n", argv[0]);
                _exit(1);
        }
        if (pid == -1)
                return NULL;
        popen_pid[myside] = pid;
        close(hisside);
        return fdopen(myside, mode);
}

Pclose(ptr)
FILE *ptr;
{
        register f, r;
        int omask;
        union wait status;
        extern int errno;

        f = fileno(ptr);
        fclose(ptr);
        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
        while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR)
                ;
        if(r == -1)
                status.w_status = -1;
        sigsetmask(omask);
        return (status.w_status);
}