/* rfsopen.c - rfsopen */

#include 

/*------------------------------------------------------------------------
 * rfsopen  -  Allocate a remote file pseudo-device for a specific file
 *------------------------------------------------------------------------
 */

devcall rfsopen (
         struct dentry  *devptr,        /* Entry in device switch table */
         char   *name,                  /* File name to use             */
         char   *mode                   /* Mode chars: 'r' 'w' 'o' 'n'  */
        )
{
        struct  rflcblk *rfptr;         /* Ptr to control block entry   */
        struct  rf_msg_oreq msg;        /* Message to be sent           */
        struct  rf_msg_ores resp;       /* Buffer to hold response      */
        int32   retval;                 /* Return value from rfscomm    */
        int32   len;                    /* Counts chars in name         */
        char    *nptr;                  /* Pointer into name string     */
        char    *fptr;                  /* Pointer into file name       */
        int32   i;                      /* General loop index           */

        /* Wait for exclusive access */

        wait(Rf_data.rf_mutex);

        /* Search control block array to find a free entry */

        for(i=0; irfstate == RF_FREE) {
                        break;
                }
        }
        if (i >= Nrfl) {                /* No free table slots remain   */
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Copy name into free table slot */

        nptr = name;
        fptr = rfptr->rfname;
        len = 0;
        while ( (*fptr++ = *nptr++) != NULLCH) {
                len++;
                if (len >= RF_NAMLEN) { /* File name is too long        */
                        signal(Rf_data.rf_mutex);
                        return SYSERR;
                }
        }

        /* Verify that name is non-null */

        if (len==0) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Parse mode string */

        if ( (rfptr->rfmode = rfsgetmode(mode)) == SYSERR ) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Form an open request to create a new file or open an old one */

        msg.rf_type = htons(RF_MSG_OREQ);/* Request a file open         */
        msg.rf_status = htons(0);
        msg.rf_seq = 0;                 /* Rfscomm fills in seq. number */
        nptr = msg.rf_name;
        memset(nptr, NULLCH, RF_NAMLEN);/* Initialize name to zero bytes*/
        while ( (*nptr++ = *name++) != NULLCH ) { /* Copy name to req.  */
                ;
        }
        msg.rf_mode = htonl(rfptr->rfmode); /* Set mode in request      */

        /* Send message and receive response */

        retval = rfscomm((struct rf_msg_hdr *)&msg,
                                        sizeof(struct rf_msg_oreq),
                         (struct rf_msg_hdr *)&resp,
                                        sizeof(struct rf_msg_ores) );

        /* Check response */

        if (retval == SYSERR) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        } else if (retval == TIMEOUT) {
                kprintf("Timeout during remote file open\n");
                signal(Rf_data.rf_mutex);
                return SYSERR;
        } else if (ntohs(resp.rf_status) != 0) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Set initial file position */

        rfptr->rfpos = 0;

        /* Mark state as currently used */

        rfptr->rfstate = RF_USED;

        /* Return device descriptor of newly created pseudo-device */

        signal(Rf_data.rf_mutex);
        return rfptr->rfdev;
}