Subversion Repositories HelenOS

/*

 * Copyright (c) 2006 Martin Decky

 * Copyright (c) 2007 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup fs

 * @{

 */

/**

 * @file    fat.c

 * @brief   FAT file system driver for HelenOS.

 */

#include <ipc/ipc.h>

#include <ipc/services.h>

#include <async.h>

#include <errno.h>

#include <unistd.h>

#include <stdio.h>

#include "../../vfs/vfs.h"

#define dprintf(...)    printf(__VA_ARGS__)

vfs_info_t fat_vfs_info = {

    .name = "fat",

    .ops = {

        [IPC_METHOD_TO_VFS_OP(VFS_REGISTER)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_OPEN)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_CREATE)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,

        [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_NULL,

        [IPC_METHOD_TO_VFS_OP(VFS_SEEK)] = VFS_OP_DEFAULT

    }

};

/**

 * This connection fibril processes VFS requests from VFS.

 *

 * In order to support simultaneous VFS requests, our design is as follows.

 * The connection fibril accepts VFS requests from VFS. If there is only one

 * instance of the fibril, VFS will need to serialize all VFS requests it sends

 * to FAT. To overcome this bottleneck, VFS can send FAT the IPC_M_CONNECT_ME_TO

 * call. In that case, a new connection fibril will be created, which in turn

 * will accept the call. Thus, a new phone will be opened for VFS.

 *

 * There are few issues with this arrangement. First, VFS can run out of

 * available phones. In that case, VFS can close some other phones or use one

 * phone for more serialized requests. Similarly, FAT can refuse to duplicate

 * the connection. VFS should then just make use of already existing phones and

 * route its requests through them. To avoid paying the fibril creation price

 * upon each request, FAT might want to keep the connections open after the

 * request has been completed.

 */

static void fat_connection(ipc_callid_t iid, ipc_call_t *icall)

{

    if (iid) {

        /*

         * This only happens for connections opened by

         * IPC_M_CONNECT_ME_TO calls as opposed to callback connections

         * created by IPC_M_CONNECT_TO_ME.

         */

        ipc_answer_fast(iid, EOK, 0, 0);

    }

    dprintf("VFS-FAT connection established.\n");

    while (1) {

        ipc_callid_t callid;

        ipc_call_t call;

        callid = async_get_call(&call);

        switch  (IPC_GET_METHOD(call)) {

        default:

            ipc_answer_fast(callid, ENOTSUP, 0, 0);

            break;

        }

    }

}

int main(int argc, char **argv)

{

    int vfs_phone;

    printf("FAT: HelenOS FAT file system server.\n");

    vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0);

    while (vfs_phone < EOK) {

        usleep(10000);

        vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0);

    }

    /*

     * Tell VFS that we are here and want to get registered.

     * We use the async framework because VFS will answer the request

     * out-of-order, when it knows that the operation succeeded or failed.

     */

    ipc_call_t answer;

    aid_t req = async_send_2(vfs_phone, VFS_REGISTER, 0, 0, &answer);

    /*

     * Send our VFS info structure to VFS.

     */

    int rc = ipc_data_send(vfs_phone, &fat_vfs_info, sizeof(fat_vfs_info));

    if (rc != EOK) {

        async_wait_for(req, NULL);

        return rc;

    }

    /*

     * Ask VFS for callback connection.

     */

    ipcarg_t phonehash;

    ipc_connect_to_me(vfs_phone, 0, 0, &phonehash);

    /*

     * Create a connection fibril to handle the callback connection.

     */

    async_new_connection(phonehash, 0, NULL, fat_connection);

    /*

     * Tell the async framework that other connections are to be handled by

     * the same connection fibril as well.

     */

    async_set_client_connection(fat_connection);

    /*

     * Pick up the answer for the request to the VFS_REQUEST call.

     */

    async_wait_for(req, NULL);

    dprintf("FAT filesystem registered.\n");

    async_create_manager();

    /*

     * TODO: Interestingly, if we merely return, the only thread dies.

     *   If the only thread dies, the whole task is destroyed.

     *   Prevent the thread from exiting when there are active fibrils.

     */

    fibril_schedule_next_adv(FIBRIL_FROM_DEAD);

    /* not reached */

    return 0;

}

/**

 * @}

 */