lfibput.c

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/* lfibput.c - lfibput */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  lfibput  -  Write an index block to disk given its ID (assumes
 *          mutex is held)
 *------------------------------------------------------------------------
 */
status  lfibput(
      did32     diskdev,    /* ID of disk device        */
      ibid32    inum,       /* ID of index block to write   */
      struct lfiblk *ibuff      /* Buffer holding the index blk */
    )
{
    dbid32  diskblock;      /* ID of disk sector (block)    */
    char    *from, *to;     /* Pointers used in copying */
    int32   i;          /* Loop index used during copy  */
    char    dbuff[LF_BLKSIZ];   /* Temp. buffer to hold d-block */

    /* Compute disk block number and offset of index block */

    diskblock = ib2sect(inum);
    to = dbuff + ib2disp(inum);
    from = (char *)ibuff;

    /* Read disk block */

    if (read(diskdev, dbuff, diskblock) == SYSERR) {
        return SYSERR;
    }

    /* Copy index block into place */

    for (i=0 ; i<sizeof(struct lfiblk) ; i++) {
        *to++ = *from++;
    }

    /* Write the block back to disk */

    write(diskdev, dbuff, diskblock);
    return OK;
}