Mount in the resource manager

Your resource manager will be called upon to perform a mount request via the mount function callout in the resmgr_connect_funcs_t structure, defined as:

int mount( resmgr_context_t *ctp,
           io_mount_t *msg,
           RESMGR_HANDLE_T *handle,
           io_mount_extra_t *extra );

The only field here that differs from the other connect functions is the io_mount_extra_t structure. It's defined in <sys/iomsg.h> as:

typedef struct _io_mount_extra {
    uint32_t flags; /* _MOUNT_? or ST_? flags above */
    uint32_t nbytes; /* Size of entire structure */
    uint32_t datalen; /* Length of the data structure following */
    uint32_t zero[1];

    union { /* If EXTRA_MOUNT_PATHNAME these set*/
        struct { /* Sent from client to resmgr framework */
            struct _msg_info32 info; /* Special info on first mount, 
                                        path info on remount */
        } cl;

        struct { /* Server receives this structure filled in */
            void * ocb; /* OCB to the special device */
            void * data; /* Server specific data of len datalen */
            char * type; /* Character string with type information */
            char * special; /* Optional special device info */
            void * zero[4]; /* Padding */
        } srv;
    } extra;
} io_mount_extra_t;

In order to receive mount requests, the resource manager should register a NULL path with an FTYPE of _FTYPE_MOUNT and with the flag _RESMGR_FLAG_FTYPEONLY. This is done with code that looks like this:

mntid = resmgr_attach(
           dpp, /* Dispatch pointer */
           &resmgr_attr, /* Dispatch attributes */
           NULL, /* Attach at "/" */
           /* We are a directory and want only matching ftypes */
           _FTYPE_MOUNT,
           _RESMGR_FLAG_DIR | _RESMGR_FLAG_FTYPEONLY,
           mount_connect, /* Only mount filled in */
           NULL, /* No io handlers */
           & handle); /* Handle to pass to mount callout */

An outline of a sample mount handler look something like this:

int io_mount( ... ) {

   Do any sanity checks that you need to do.

   Check type against our type with strcmp(), since
   there may be no name for REMOUNT/UNMOUNT flags.

   Error out with ENOENT if no match.

   If no name, check the validity of the REMOUNT/UNMOUNT request.

   Parse arguments or set up your data structure.

   Check to see if we are remounting (_MOUNT_REMOUNT)

      Change flags, etc., if you can remount.
      Return EOK.

   Check to see if we are unmounting _MOUNT_UNMOUNT

      Change flags, etc., if you can unmount.
      Return EOK.

   Create a new node and attach it at the msg->connect.path
   point (unless some other path is implied based on the
   input variables and the resource manager) with resmgr_attach().

   Return EOK.
}