rfsopen.c

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/* rfsopen.c - rfsopen */

#include <xinu.h>

/*------------------------------------------------------------------------
 * 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; i<Nrfl; i++) {
        rfptr = &rfltab[i];
        if (rfptr->rfstate == 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\r");
        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;
}