lflcontrol.c

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/* lflcontrol.c - lflcontrol */

#include <xinu.h>

/*------------------------------------------------------------------------
 * lflcontrol  -  Provide control functions for a local file pseudo-device
 *------------------------------------------------------------------------
 */
devcall lflcontrol (
     struct dentry  *devptr,    /* Entry in device switch table */
     int32  func,           /* A control function       */
     int32  arg1,           /* Argument #1          */
     int32  arg2            /* Argument #2          */
    )
{
    struct  lflcblk *lfptr;     /* Ptr to open file table entry */
    int32   retval;         /* Return value from func. call */

    /* Obtain exclusive use of the file */

    lfptr = &lfltab[devptr->dvminor];
    wait(lfptr->lfmutex);

    /* If file is not open, return an error */

    if (lfptr->lfstate != LF_USED) {
        signal(lfptr->lfmutex);
        return SYSERR;
    }

    switch (func) {

    /* Truncate a file */

    case LF_CTL_TRUNC:
        wait(Lf_data.lf_mutex);
        retval = lftruncate(lfptr);
        signal(Lf_data.lf_mutex);
        signal(lfptr->lfmutex);
        return retval;  

    default:
        kprintf("lfcontrol: function %d not valid\n\r", func);
        signal(lfptr->lfmutex);
        return SYSERR;
    }
}