rdscontrol.c

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/* rdscontrol.c - rdscontrol */

#include <xinu.h>

/*------------------------------------------------------------------------
 * rdscontrol  -  Provide control functions for the remote disk
 *------------------------------------------------------------------------
 */
devcall rdscontrol (
     struct dentry  *devptr,    /* Entry in device switch table */
     int32  func,           /* The control function to use  */
     int32  arg1,           /* Argument #1          */
     int32  arg2            /* Argument #2          */
    )
{
    struct  rdscblk *rdptr;     /* Pointer to control block */
    struct  rdbuff  *bptr;      /* Ptr to buffer that will be   */
                    /*   placed on the req. queue   */
    struct  rdbuff  *pptr;      /* Ptr to "previous" node on    */
                    /*   a list         */
    struct  rd_msg_dreq msg;    /* Buffer for delete request    */
    struct  rd_msg_dres resp;   /* Buffer for delete response   */
    char    *to, *from;     /* Used during name copy    */
    int32   retval;         /* Return value         */

    /* Verify that device is currently open */

    rdptr = &rdstab[devptr->dvminor];
    if (rdptr->rd_state != RD_OPEN) {
        return SYSERR;
    }

    /* Ensure rdsprocess is runnning */

    if ( ! rdptr->rd_comruns ) {
        rdptr->rd_comruns = TRUE;
        resume(rdptr->rd_comproc);
    }

    switch (func) {

    /* Synchronize writes */

    case RDS_CTL_SYNC:

        /* Allocate a buffer to use for the request list */

        bptr = rdsbufalloc(rdptr);
        if (bptr == (struct rdbuff *)SYSERR) {
            return SYSERR;
        }

        /* Form a sync request */

        bptr->rd_op = RD_OP_SYNC;
        bptr->rd_refcnt = 1;
        bptr->rd_blknum = 0;        /* Unused */
        bptr->rd_status = RD_INVALID;
        bptr->rd_pid = getpid();

        /* Insert new request into list just before tail */

        pptr = rdptr->rd_rtprev;
        rdptr->rd_rtprev = bptr;
        bptr->rd_next = pptr->rd_next;
        bptr->rd_prev = pptr;
        pptr->rd_next = bptr;

        /* Prepare to wait until item is processed */

        recvclr();

        /* Signal then semaphore to start communication */

        signal(rdptr->rd_reqsem);

        /* Block to wait for a message */

        bptr = (struct rdbuff *)receive();
        if (bptr == (struct rdbuff *)SYSERR) {  
            return SYSERR;
        }
        break;

    /* Delete the remote disk (entirely remove it) */

    case RDS_CTL_DEL:

        /* Handcraft a message for the server that requests */
        /*  deleting the disk with the specified ID     */

        msg.rd_type = htons(RD_MSG_DREQ);/* Request deletion    */
        msg.rd_status = htons(0);
        msg.rd_seq = 0; /* rdscomm will insert sequence # later */
        to = msg.rd_id;
        memset(to, NULLCH, RD_IDLEN);   /* Initialize to zeroes */
        from = rdptr->rd_id;
        while ( (*to++ = *from++) != NULLCH ) { /* copy ID  */
            ;
        }

        /* Send message and receive response */

        retval = rdscomm((struct rd_msg_hdr *)&msg,
                    sizeof(struct rd_msg_dreq),
             (struct rd_msg_hdr *)&resp,
                    sizeof(struct rd_msg_dres),
                    rdptr);

        /* Check response */

        if (retval == SYSERR) {
            return SYSERR;
        } else if (retval == TIMEOUT) {
            kprintf("Timeout during remote file delete\n\r");
            return SYSERR;
        } else if (ntohs(resp.rd_status) != 0) {
            return SYSERR;
        }

        /* Close local device */

        return rdsclose(devptr);

    default:
        kprintf("rfsControl: function %d not valid\n\r", func);
        return SYSERR;
    }

    return OK;
}