source: mainline/uspace/srv/fs/fat/fat.c@ a4627c4

/*
 * 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;
}

/**
 * @}
 */