/* lfscheck.c - lfscheck */

#include 
#include 

/*------------------------------------------------------------------------
 * lfscheck  -  Check a directory to verify it contains a Xinu file system
 *------------------------------------------------------------------------
 */
status  lfscheck (
          struct lfdir  *dirptr         /* Ptr to an in-core directory  */
        )
{
        uint32  reverse;                /* LFS_ID in reverse byte order */

        /* Verify the File System ID, all 0's and all 1's fields */

        if ( (dirptr->lfd_fsysid != LFS_ID)       ||
             (dirptr->lfd_allzeros != 0x00000000) ||
             (dirptr->lfd_allones  != 0xffffffff) ) {
                return SYSERR;
        }

        /* Check the reverse-order File System ID field */

        reverse = ((LFS_ID>>24) & 0x000000ff) | 
                  ((LFS_ID>> 8) & 0x0000ff00) |
                  ((LFS_ID<< 8) & 0x00ff0000) |
                  ((LFS_ID<<24) & 0xff000000) ;

        if (dirptr->lfd_revid != reverse) {
                return SYSERR;
        }

        /* Extra sanity check - verify file count is non-negative */

        if (dirptr->lfd_nfiles < 0){
                return SYSERR;
        }
        return OK;
}