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Annotation of src/usr.bin/rdist/rshrcmd.c, Revision 1.1

1.1     ! dm          1:
        !             2: /*
        !             3:  * This is an rcmd() replacement originally by
        !             4:  * Chris Siebenmann <cks@utcc.utoronto.ca>.
        !             5:  */
        !             6:
        !             7: #ifndef lint
        !             8: static char RCSid[] =
        !             9: "$Id: rshrcmd.c,v 1.7 1995/12/12 00:20:55 mcooper Exp $";
        !            10: #endif
        !            11:
        !            12: #include       "defs.h"
        !            13:
        !            14: #if    !defined(DIRECT_RCMD)
        !            15:
        !            16: #include      <sys/types.h>
        !            17: #include      <sys/socket.h>
        !            18: #include      <sys/wait.h>
        !            19: #include      <signal.h>
        !            20: #include      <errno.h>
        !            21: #include      <netdb.h>
        !            22: #include      <stdio.h>
        !            23:
        !            24: /*
        !            25:  * This is a replacement rcmd() function that uses the rsh(1c)
        !            26:  * program in place of a direct rcmd() function call so as to
        !            27:  * avoid having to be root.
        !            28:  */
        !            29: rshrcmd(ahost, port, luser, ruser, cmd, fd2p)
        !            30:        char    **ahost;
        !            31:        u_short port;
        !            32:        char    *luser, *ruser, *cmd;
        !            33:        int     *fd2p;
        !            34: {
        !            35:        int             cpid;
        !            36:        struct hostent  *hp;
        !            37:        int             sp[2];
        !            38:
        !            39:        /* insure that we are indeed being used as we thought. */
        !            40:        if (fd2p != 0)
        !            41:                return -1;
        !            42:        /* validate remote hostname. */
        !            43:        hp = gethostbyname(*ahost);
        !            44:        if (hp == 0) {
        !            45:                error("%s: unknown host", *ahost);
        !            46:                return -1;
        !            47:        }
        !            48:        /* *ahost = hp->h_name; /* This makes me nervous. */
        !            49:
        !            50:        /* get a socketpair we'll use for stdin and stdout. */
        !            51:        if (getsocketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0) {
        !            52:                error("socketpair(AF_UNIX, SOCK_STREAM, 0) failed: %s.",
        !            53:                      SYSERR);
        !            54:                return -1;
        !            55:        }
        !            56:
        !            57:        cpid = fork();
        !            58:        if (cpid < 0) {
        !            59:                error("fork failed: %s.", SYSERR);
        !            60:                return -1;      /* error. */
        !            61:        }
        !            62:        if (cpid == 0) {
        !            63:                /* child. we use sp[1] to be stdin/stdout, and close
        !            64:                   sp[0]. */
        !            65:                (void) close(sp[0]);
        !            66:                if (dup2(sp[1], 0) < 0 || dup2(0,1) < 0 || dup2(0, 2) < 0) {
        !            67:                        error("dup2 failed: %s.", SYSERR);
        !            68:                        _exit(255);
        !            69:                }
        !            70:                /* fork again to lose parent. */
        !            71:                cpid = fork();
        !            72:                if (cpid < 0) {
        !            73:                        error("fork to lose parent failed: %s.", SYSERR);
        !            74:                        _exit(255);
        !            75:                }
        !            76:                if (cpid > 0)
        !            77:                        _exit(0);
        !            78:                /* in grandchild here. */
        !            79:
        !            80:                /*
        !            81:                 * If we are rdist'ing to "localhost" as the same user
        !            82:                 * as we are, then avoid running remote shell for efficiency.
        !            83:                 */
        !            84:                if (strcmp(*ahost, "localhost") == 0 &&
        !            85:                    strcmp(luser, ruser) == 0) {
        !            86:                        execlp(_PATH_BSHELL, xbasename(_PATH_BSHELL), "-c",
        !            87:                               cmd, (char *) NULL);
        !            88:                        error("execlp %s failed: %s.", _PATH_BSHELL, SYSERR);
        !            89:                } else {
        !            90:                        execlp(path_remsh, xbasename(path_remsh),
        !            91:                               *ahost, "-l", ruser, cmd, (char *) NULL);
        !            92:                        error("execlp %s failed: %s.", path_remsh, SYSERR);
        !            93:                }
        !            94:                _exit(255);
        !            95:        }
        !            96:        if (cpid > 0) {
        !            97:                /* parent. close sp[1], return sp[0]. */
        !            98:                (void) close(sp[1]);
        !            99:                /* reap child. */
        !           100:                (void) wait(0);
        !           101:                return sp[0];
        !           102:        }
        !           103:        /*NOTREACHED*/
        !           104: }
        !           105:
        !           106: #endif /* !DIRECT_RCMD */