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Annotation of 43BSDTahoe/ucb/Mail/popen.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that this notice is preserved and that due credit is given
        !             7:  * to the University of California at Berkeley. The name of the University
        !             8:  * may not be used to endorse or promote products derived from this
        !             9:  * software without specific prior written permission. This software
        !            10:  * is provided ``as is'' without express or implied warranty.
        !            11:  */
        !            12: 
        !            13: #ifdef notdef
        !            14: static char sccsid[] = "@(#)popen.c    5.4 (Berkeley) 2/18/88";
        !            15: #endif /* notdef */
        !            16: 
        !            17: #include <stdio.h>
        !            18: #include <sys/signal.h>
        !            19: #include <sys/types.h>
        !            20: #include <sys/wait.h>
        !            21: #include <errno.h>
        !            22: 
        !            23: #define        tst(a,b)        (*mode == 'r'? (b) : (a))
        !            24: #define        RDR     0
        !            25: #define        WTR     1
        !            26: static int     popen_pid[20];
        !            27: 
        !            28: FILE *
        !            29: popen(cmd,mode)
        !            30: char   *cmd;
        !            31: char   *mode;
        !            32: {
        !            33:        int p[2];
        !            34:        register myside, hisside, pid;
        !            35: 
        !            36:        if(pipe(p) < 0)
        !            37:                return NULL;
        !            38:        myside = tst(p[WTR], p[RDR]);
        !            39:        hisside = tst(p[RDR], p[WTR]);
        !            40:        if((pid = vfork()) == 0) {
        !            41:                /* myside and hisside reverse roles in child */
        !            42:                close(myside);
        !            43:                dup2(hisside, tst(0, 1));
        !            44:                close(hisside);
        !            45:                execl("/bin/csh", "sh", "-c", cmd, 0);
        !            46:                _exit(1);
        !            47:        }
        !            48:        if(pid == -1)
        !            49:                return NULL;
        !            50:        popen_pid[myside] = pid;
        !            51:        close(hisside);
        !            52:        return(fdopen(myside, mode));
        !            53: }
        !            54: 
        !            55: pclose(ptr)
        !            56: FILE *ptr;
        !            57: {
        !            58:        register f, r;
        !            59:        int omask;
        !            60:        union wait status;
        !            61:        extern int errno;
        !            62: 
        !            63:        f = fileno(ptr);
        !            64:        fclose(ptr);
        !            65:        omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
        !            66:        while((r = wait(&status)) != popen_pid[f] && r != -1 && errno != EINTR)
        !            67:                ;
        !            68:        if(r == -1)
        !            69:                status.w_status = -1;
        !            70:        sigsetmask(omask);
        !            71:        return (status.w_status);
        !            72: }

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