Directory Listing Program and Support Routines (rpcgen)

Example D-1 rpcgen Program: dir.x

/*
 * dir.x: Remote directory listing
 * protocol
 *
 * This source module is a rpcgen source module
 * used to demonstrate the functions of the rpcgen
 * tool.
 *
 * It is compiled with the rpcgen -h -T switches to
 * generate both the header (.h) file and the
 * accompanying data structures.
 */
const MAXNAMELEN = 255; /*maxlengthofadirectoryentry*/
typedef string nametype<MAXNAMELEN>; /* directory entry */
typedef struct namenode *namelist; /* linkinthelisting*/

/* A node in the directory listing */
struct namenode {
    nametype name; /* name of directory entry */
    namelist next; /* next entry */
};

/*
 * The result of a READDIR operation:
 * a truly portable application would use an agreed upon list of
 * error codes rather than, as this sample program does, rely upon
 * passing UNIX errno's back. In this example the union is used to
 * discriminate between successful and unsuccessful remote calls.
 */
union readdir_res switch (int errno) {
    case 0:
        namelist list; /*no error: return directory listing*/
    default:
        void; /*error occurred: nothing else to return*/
};

/* The directory program definition */
program DIRPROG {
    version DIRVERS {
        readdir_res
        READDIR(nametype) = 1;
    } = 1;
} = 0x20000076;

Example D-2 Remote dir_proc.c

/*
 * dir_proc.c: remote readdir implementation
 */
#include <rpc/rpc.h>      /* Always needed */
#include <dirent.h>
#include "dir.h"          /* Created by rpcgen */

extern int errno;
extern char *malloc();
extern char *strdup();

/* ARGSUSED1*/
readdir_res *
readdir_1(dirname,req)
     nametype *dirname;
     struct svc_req *req;
{
     DIR *dirp;
     struct dirent *d;
     namelist nl;
     namelist *nlp;
     static readdir_res res; /* must be static! */

    /*
     * Open directory
     */
    dirp = opendir(*dirname);
    if (dirp == (DIR *)NULL) {
         res.errno = errno;
         return (&res);
     }
    /*
     * Free previous result
     */
    xdr_free(xdr_readdir_res, &res);
    /*
     * Collect directory entries. Memory allocated here is freed
     * by xdr_free the next time readdir_1 is called.
     */

     nlp = &res.readdir_res_u.list;
     while (d = readdir(dirp)) {
         nl = *nlp = (namenode *) malloc(sizeof(namenode));
         if (nl == (namenode *) NULL) {
             res.errno = EAGAIN;
             closedir(dirp);
             return(&res);
         }
         nl->name = strdup(d->d_name);
         nlp = &nl->next;
     }
     *nlp = (namelist)NULL;
     /* Return the result */
     res.errno = 0;
     closedir(dirp);
     return (&res);
}

Example D-3 rls.c Client

/*
 * rls.c: Remote directory listing client
 */

#include <stdio.h>
#include <rpc/rpc.h>    /* always need this */
#include "dir.h"        /* generated by rpcgen */

extern int errno;

main(argc, argv)
     int argc;
     char *argv[];
{
     CLIENT *cl;
     char *server;
     char *dir;
     readdir_res *result;
     namelist nl;

    if (argc != 3) {
        fprintf(stderr, "usage: %s host directory\n",
        argv[0]);
        exit(1);
    }
    server = argv[1];
     dir = argv[2];
/*
 * Create client "handle" used for calling MESSAGEPROG on the
 * server designated on the command line.
 */
    cl = clnt_create(server, DIRPROG, DIRVERS, "visible");
     if (cl == (CLIENT *)NULL) {
         clnt_pcreateerror(server);
         exit(1);
     }

     result = readdir_1(&dir, cl);
     if (result == (readdir_res *)NULL) {
         clnt_perror(cl, server);
         exit(1);
     }

/* Okay, we successfully called the remote procedure. */
    if (result->errno != 0) {
    /*
     * A remote system error occurred. Print error message and die.
     */
    }
    if (result->errno < sys_nerr)
         fprintf (stderr, "%s : %s\n", dir,
         sys_enlist[result->errno]);
         errno = result->errno;
         perror(dir);
         exit(1);
     }

/* Successfully got a directory listing. Print it out. */
    for(nl = result->readdir_res_u.list; nl != NULL;
                        nl = nl->next) {
        printf("%s\n", nl->name);
    }
exit(0);