| 1 | /*
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| 2 | * Copyright (c) 2007 Jakub Jermar
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup fs
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| 30 | * @{
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| 31 | */
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| 32 |
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| 33 | /**
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| 34 | * @file vfs_read.c
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| 35 | * @brief
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| 36 | */
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| 37 |
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| 38 | #include "vfs.h"
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| 39 | #include <ipc/ipc.h>
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| 40 | #include <async.h>
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| 41 | #include <errno.h>
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| 42 |
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| 43 | void vfs_read(ipc_callid_t rid, ipc_call_t *request)
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| 44 | {
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| 45 |
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| 46 | /*
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| 47 | * The following code strongly depends on the fact that the files data
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| 48 | * structure can be only accessed by a single fibril and all file
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| 49 | * operations are serialized (i.e. the reads and writes cannot
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| 50 | * interleave and a file cannot be closed while it is being read).
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| 51 | *
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| 52 | * Additional synchronization needs to be added once table table of
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| 53 | * open files supports parallel access!
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| 54 | */
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| 55 |
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| 56 | /*
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| 57 | * Because we don't support the receive analogy of IPC_M_DATA_SEND,
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| 58 | * VFS_READ is emulutating its behavior via sharing an address space
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| 59 | * area.
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| 60 | */
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| 61 |
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| 62 | int fd = IPC_GET_ARG1(*request);
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| 63 |
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| 64 | /*
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| 65 | * Lookup the file structure corresponding to the file descriptor.
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| 66 | */
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| 67 | vfs_file_t *file = vfs_file_get(fd);
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| 68 | if (!file) {
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| 69 | ipc_answer_0(rid, ENOENT);
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| 70 | return;
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| 71 | }
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| 72 |
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| 73 | /*
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| 74 | * Now we need to receive a call with client's address space area.
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| 75 | */
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| 76 | ipc_callid_t callid;
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| 77 | ipc_call_t call;
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| 78 | callid = async_get_call(&call);
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| 79 | if (IPC_GET_METHOD(call) != IPC_M_AS_AREA_SEND) {
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| 80 | ipc_answer_0(callid, EINVAL);
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| 81 | ipc_answer_0(rid, EINVAL);
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| 82 | return;
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| 83 | }
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| 84 |
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| 85 | int fs_phone = vfs_grab_phone(file->node->fs_handle);
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| 86 |
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| 87 | /*
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| 88 | * Make a VFS_READ request at the destination FS server.
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| 89 | */
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| 90 | aid_t msg;
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| 91 | msg = async_send_3(fs_phone, VFS_READ, file->node->dev_handle,
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| 92 | file->node->index, file->pos, NULL);
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| 93 |
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| 94 | /*
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| 95 | * Forward the address space area offer to the destination FS server.
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| 96 | * The call will be routed as if sent by ourselves.
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| 97 | */
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| 98 | ipc_forward_fast(callid, fs_phone, IPC_GET_METHOD(call),
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| 99 | IPC_GET_ARG1(call), 0, IPC_FF_ROUTE_FROM_ME);
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| 100 |
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| 101 | vfs_release_phone(fs_phone);
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| 102 |
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| 103 | /*
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| 104 | * Wait for reply from the FS server.
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| 105 | */
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| 106 | ipcarg_t rc;
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| 107 | async_wait_for(msg, &rc);
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| 108 |
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| 109 | /*
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| 110 | * FS server's reply is the final result of the whole operation we
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| 111 | * return to the client.
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| 112 | */
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| 113 | ipc_answer_0(rid, rc);
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| 114 | }
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| 115 |
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| 116 | /**
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| 117 | * @}
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| 118 | */
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