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2625 | jermar | 1 | /* |
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 | |||
29 | /** @addtogroup fs |
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30 | * @{ |
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31 | */ |
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32 | |||
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 | |||
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 | |||
43 | void vfs_read(ipc_callid_t rid, ipc_call_t *request) |
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44 | { |
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45 | |||
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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2658 | jermar | 52 | * Additional synchronization needs to be added once the table of |
2625 | jermar | 53 | * open files supports parallel access! |
54 | */ |
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55 | |||
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 | |||
62 | int fd = IPC_GET_ARG1(*request); |
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2658 | jermar | 63 | size_t size = IPC_GET_ARG2(*request); |
2625 | jermar | 64 | |
65 | /* |
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66 | * Lookup the file structure corresponding to the file descriptor. |
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67 | */ |
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68 | vfs_file_t *file = vfs_file_get(fd); |
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69 | if (!file) { |
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70 | ipc_answer_0(rid, ENOENT); |
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71 | return; |
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72 | } |
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73 | |||
74 | /* |
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75 | * Now we need to receive a call with client's address space area. |
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76 | */ |
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77 | ipc_callid_t callid; |
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78 | ipc_call_t call; |
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79 | callid = async_get_call(&call); |
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80 | if (IPC_GET_METHOD(call) != IPC_M_AS_AREA_SEND) { |
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81 | ipc_answer_0(callid, EINVAL); |
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82 | ipc_answer_0(rid, EINVAL); |
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83 | return; |
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84 | } |
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85 | |||
86 | int fs_phone = vfs_grab_phone(file->node->fs_handle); |
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87 | |||
88 | /* |
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89 | * Make a VFS_READ request at the destination FS server. |
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90 | */ |
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91 | aid_t msg; |
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2658 | jermar | 92 | ipc_call_t answer; |
93 | msg = async_send_4(fs_phone, VFS_READ, file->node->dev_handle, |
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94 | file->node->index, file->pos, size, &answer); |
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2625 | jermar | 95 | |
96 | /* |
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97 | * Forward the address space area offer to the destination FS server. |
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98 | * The call will be routed as if sent by ourselves. |
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99 | */ |
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100 | ipc_forward_fast(callid, fs_phone, IPC_GET_METHOD(call), |
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2635 | cejka | 101 | IPC_GET_ARG1(call), 0, IPC_FF_ROUTE_FROM_ME); |
2625 | jermar | 102 | |
103 | vfs_release_phone(fs_phone); |
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104 | |||
105 | /* |
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106 | * Wait for reply from the FS server. |
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107 | */ |
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108 | ipcarg_t rc; |
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109 | async_wait_for(msg, &rc); |
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2658 | jermar | 110 | size_t bytes = IPC_GET_ARG1(answer); |
2625 | jermar | 111 | |
112 | /* |
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113 | * FS server's reply is the final result of the whole operation we |
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114 | * return to the client. |
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115 | */ |
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2658 | jermar | 116 | ipc_answer_1(rid, rc, bytes); |
2625 | jermar | 117 | } |
118 | |||
119 | /** |
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120 | * @} |
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121 | */ |