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2625 jermar 1 
/*
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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    vfs_rdwr.c
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 * @brief
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 */
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#include "vfs.h"
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#include <ipc/ipc.h>
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#include <async.h>
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#include <errno.h>
2680 jermar 42 
#include <rwlock.h>
2625 jermar 43 
 
2666 jermar 44 
static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
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{
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    /*
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     * The following code strongly depends on the fact that the files data
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     * structure can be only accessed by a single fibril and all file
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     * operations are serialized (i.e. the reads and writes cannot
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     * interleave and a file cannot be closed while it is being read).
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     *
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     * Additional synchronization needs to be added once the table of
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     * open files supports parallel access!
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     */
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    int fd = IPC_GET_ARG1(*request);
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    /*
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     * Lookup the file structure corresponding to the file descriptor.
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     */
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    vfs_file_t *file = vfs_file_get(fd);
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    if (!file) {
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        ipc_answer_0(rid, ENOENT);
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        return;
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    }
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    /*
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     * Now we need to receive a call with client's
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     * IPC_M_DATA_READ/IPC_M_DATA_WRITE request.
2625 jermar 71 
     */
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    ipc_callid_t callid;
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    int res;
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    if (read)
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        res = ipc_data_read_receive(&callid, NULL);
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    else
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        res = ipc_data_write_receive(&callid, NULL);
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    if (!res) {
2625 jermar 79 
        ipc_answer_0(callid, EINVAL);
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        ipc_answer_0(rid, EINVAL);
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        return;
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    }
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2679 jermar 84 
    /*
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     * Lock the open file structure so that no other thread can manipulate
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     * the same open file at a time.
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     */
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    futex_down(&file->lock);
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    /*
2679 jermar 91 
     * Lock the file's node so that no other client can read/write to it at
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     * the same time.
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     */
2680 jermar 94 
    if (read)
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        rwlock_reader_lock(&file->node->contents_rwlock);
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    else
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        rwlock_writer_lock(&file->node->contents_rwlock);
2679 jermar 98 
 
2625 jermar 99 
    int fs_phone = vfs_grab_phone(file->node->fs_handle);  
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    /*
2666 jermar 102 
     * Make a VFS_READ/VFS_WRITE request at the destination FS server.
2625 jermar 103 
     */
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    aid_t msg;
2658 jermar 105 
    ipc_call_t answer;
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    msg = async_send_3(fs_phone, IPC_GET_METHOD(*request),
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        file->node->dev_handle, file->node->index, file->pos, &answer);
2625 jermar 108 
 
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    /*
2666 jermar 110 
     * Forward the IPC_M_DATA_READ/IPC_M_DATA_WRITE request to the
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     * destination FS server. The call will be routed as if sent by
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     * ourselves. Note that call arguments are immutable in this case so we
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     * don't have to bother.
2625 jermar 114 
     */
2663 jermar 115 
    ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME);
2625 jermar 116 
 
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    vfs_release_phone(fs_phone);
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    /*
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     * Wait for reply from the FS server.
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     */
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    ipcarg_t rc;
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    async_wait_for(msg, &rc);
2658 jermar 124 
    size_t bytes = IPC_GET_ARG1(answer);
2625 jermar 125 
 
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    /*
2679 jermar 127 
     * Unlock the VFS node.
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     */
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    if (read)
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        rwlock_reader_unlock(&file->node->contents_rwlock);
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    else
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        rwlock_writer_unlock(&file->node->contents_rwlock);
2679 jermar 133 
 
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    /*
2683 jermar 135 
     * Update the position pointer and unlock the open file.
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     */
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    file->pos += bytes;
2683 jermar 138 
    futex_up(&file->lock);
2659 jermar 139 
 
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    /*
2625 jermar 141 
     * FS server's reply is the final result of the whole operation we
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     * return to the client.
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     */
2658 jermar 144 
    ipc_answer_1(rid, rc, bytes);
2625 jermar 145 
}
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2666 jermar 147 
 
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void vfs_read(ipc_callid_t rid, ipc_call_t *request)
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{
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    vfs_rdwr(rid, request, true);
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}
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void vfs_write(ipc_callid_t rid, ipc_call_t *request)
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{
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    vfs_rdwr(rid, request, false);
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}
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2625 jermar 158 
/**
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 * @}
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 */