/* rflread.c - rflread */

#include 

/*------------------------------------------------------------------------
 * rflread  -  Read data from a remote file
 *------------------------------------------------------------------------
 */
devcall rflread (
          struct dentry *devptr,        /* Entry in device switch table */
          char  *buff,                  /* Buffer of bytes              */
          int32 count                   /* Count of bytes to read       */
        )
{
        struct  rflcblk *rfptr;         /* Pointer to control block     */
        int32   retval;                 /* Return value                 */
        struct  rf_msg_rreq  msg;       /* Request message to send      */
        struct  rf_msg_rres resp;       /* Buffer for response          */
        int32   i;                      /* Counts bytes copied          */
        char    *from, *to;             /* Used during name copy        */
        int32   len;                    /* Length of name               */

        /* Wait for exclusive access */

        wait(Rf_data.rf_mutex);

        /* Verify count is legitimate */

        if ( (count <= 0) || (count > RF_DATALEN) ) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Verify pseudo-device is in use */

        rfptr = &rfltab[devptr->dvminor];

        /* If device not currently in use, report an error */

        if (rfptr->rfstate == RF_FREE) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Verify pseudo-device allows reading */

        if ((rfptr->rfmode & RF_MODE_R) == 0) {
                signal(Rf_data.rf_mutex);
                return SYSERR;
        }

        /* Form read request */

        msg.rf_type = htons(RF_MSG_RREQ);
        msg.rf_status = htons(0);
        msg.rf_seq = 0;                 /* Rfscomm will set sequence    */
        from = rfptr->rfname;
        to = msg.rf_name;
        memset(to, NULLCH, RF_NAMLEN);  /* Start name as all zero bytes */
        len = 0;
        while ( (*to++ = *from++) ) {   /* Copy name to request         */
                if (++len >= RF_NAMLEN) {
                        signal(Rf_data.rf_mutex);
                        return SYSERR;
                }
        }
        msg.rf_pos = htonl(rfptr->rfpos);/* Set file position           */
        msg.rf_len = htonl(count);      /* Set count of bytes to read   */

        /* Send message and receive response */

        retval = rfscomm((struct rf_msg_hdr *)&msg,
                                        sizeof(struct rf_msg_rreq),
                         (struct rf_msg_hdr *)&resp,
                                        sizeof(struct rf_msg_rres) );

        /* Check response */

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

        /* Copy data to application buffer and update file position */

        for (i=0; irfpos += ntohl(resp.rf_len);

        signal(Rf_data.rf_mutex);
        if (ntohl(resp.rf_len) == 0) {
                return EOF;
        }
        return ntohl(resp.rf_len);
}