mount.c

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/* mount.c - mount, namlen */

#include <xinu.h>

/*------------------------------------------------------------------------
 *  mount  -  Add a prefix mapping to the name space
 *------------------------------------------------------------------------
 */
syscall mount(
      char      *prefix,    /* Prefix to add        */
      char      *replace,   /* Replacement string       */
      did32     device      /* Device ID to use     */
)
{
    intmask mask;           /* Saved interrupt mask     */
    struct  nmentry *namptr;    /* Pointer to unused table entry*/
    int32   psiz, rsiz;     /* Sizes of prefix & replacement*/
    int32   i;          /* Counter for copy loop    */

        mask = disable();

    psiz = namlen(prefix, NM_PRELEN);
    rsiz = namlen(replace, NM_REPLLEN);

    /* If arguments are invalid or table is full, return error */

    if ( (psiz == SYSERR)   || (rsiz == SYSERR) ||
         (isbaddev(device)) || (nnames >= NNAMES) ) {
        restore(mask);
        return SYSERR;
    }

    /* Allocate a slot in the table */

    namptr = &nametab[nnames];  /* Next unused entry in table   */

    /* copy prefix and replacement strings and record device ID */
    
    for (i=0; i<psiz; i++) {    /* Copy prefix into table entry */
        namptr->nprefix[i] = *prefix++;
    }

    for (i=0; i<rsiz; i++) {    /* Copy replacement into entry  */
        namptr->nreplace[i] = *replace++;
    }

    namptr->ndevice = device;   /* Record the device ID     */

        nnames++;           /* Increment number of names    */

    restore(mask);
    return OK;
}


/*------------------------------------------------------------------------
 *  namlen  -  Compute the length of a string stopping at maxlen
 *------------------------------------------------------------------------
 */
int32   namlen(
      char      *name,      /* Name to use          */
      int32     maxlen      /* Maximum length (including a  */
                    /*   NULLCH)            */
)
{
    int32   i;          /* Count of characters found    */

    /* Search until a null terminator or length reaches max */

    for (i=0; i < maxlen; i++) {
        if (*name++ == NULLCH) {
            return i+1; /* Include NULLCH in length */
        }
    }
    return SYSERR;
}