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2006 decky 1 
/*
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 * Copyright (c) 2006 Martin Decky
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 * Copyright (c) 2007 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup fs
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 * @{
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 */
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/**
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 * @file    fat.c
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 * @brief   FAT file system driver for HelenOS.
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 */
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#include "fat.h"
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#include <ipc/ipc.h>
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#include <ipc/services.h>
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#include <async.h>
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#include <errno.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <libfs.h>
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#include "../../vfs/vfs.h"
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vfs_info_t fat_vfs_info = {
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    .name = "fat",
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    .ops = {
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        [IPC_METHOD_TO_VFS_OP(VFS_REGISTER)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_MOUNT)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_UNMOUNT)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_LOOKUP)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_OPEN)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_CREATE)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_CLOSE)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_READ)] = VFS_OP_DEFINED,
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        [IPC_METHOD_TO_VFS_OP(VFS_WRITE)] = VFS_OP_NULL,
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        [IPC_METHOD_TO_VFS_OP(VFS_SEEK)] = VFS_OP_DEFAULT
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    }
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};
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fs_reg_t fat_reg;
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/**
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 * This connection fibril processes VFS requests from VFS.
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 *
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 * In order to support simultaneous VFS requests, our design is as follows.
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 * The connection fibril accepts VFS requests from VFS. If there is only one
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 * instance of the fibril, VFS will need to serialize all VFS requests it sends
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 * to FAT. To overcome this bottleneck, VFS can send FAT the IPC_M_CONNECT_ME_TO
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 * call. In that case, a new connection fibril will be created, which in turn
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 * will accept the call. Thus, a new phone will be opened for VFS.
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 *
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 * There are few issues with this arrangement. First, VFS can run out of
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 * available phones. In that case, VFS can close some other phones or use one
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 * phone for more serialized requests. Similarily, FAT can refuse to duplicate
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 * the connection. VFS should then just make use of already existing phones and
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 * route its requests through them. To avoid paying the fibril creation price
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 * upon each request, FAT might want to keep the connections open after the
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 * request has been completed.
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 */
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static void fat_connection(ipc_callid_t iid, ipc_call_t *icall)
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{
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    if (iid) {
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        /*
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         * This only happens for connections opened by
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         * IPC_M_CONNECT_ME_TO calls as opposed to callback connections
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         * created by IPC_M_CONNECT_TO_ME.
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         */
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        ipc_answer_0(iid, EOK);
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    }
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    dprintf("VFS-FAT connection established.\n");
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    while (1) {
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        ipc_callid_t callid;
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        ipc_call_t call;
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        callid = async_get_call(&call);
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        switch  (IPC_GET_METHOD(call)) {
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        case VFS_REGISTER:
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            ipc_answer_0(callid, EOK);
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            break;
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        case VFS_LOOKUP:
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            fat_lookup(callid, &call);
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            break;
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        default:
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            ipc_answer_0(callid, ENOTSUP);
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            break;
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        }
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    }
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}
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int main(int argc, char **argv)
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{
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    int vfs_phone;
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    printf("FAT: HelenOS FAT file system server.\n");
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    vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
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    while (vfs_phone < EOK) {
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        usleep(10000);
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        vfs_phone = ipc_connect_me_to(PHONE_NS, SERVICE_VFS, 0, 0);
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    }
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    int rc;
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    rc = fs_register(vfs_phone, &fat_reg, &fat_vfs_info, fat_connection);
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    if (rc != EOK) {
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        printf("Failed to register the FAT file system (%d)\n", rc);
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        return rc;
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    }
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    dprintf("FAT filesystem registered, fs_handle=%d.\n",
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        fat_reg.fs_handle);
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    async_manager();
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    /* not reached */
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    return 0;
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}
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/**
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 * @}
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 */