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Annotation of src/usr.bin/rdist/rshrcmd.c, Revision 1.2

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 */