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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 | int fd = IPC_GET_ARG1(*request); |
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57 | |||
58 | /* |
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59 | * Lookup the file structure corresponding to the file descriptor. |
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60 | */ |
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61 | vfs_file_t *file = vfs_file_get(fd); |
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62 | if (!file) { |
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63 | ipc_answer_0(rid, ENOENT); |
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64 | return; |
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65 | } |
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66 | |||
67 | /* |
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2663 | jermar | 68 | * Now we need to receive a call with client's IPC_M_DATA_READ request. |
2625 | jermar | 69 | */ |
70 | ipc_callid_t callid; |
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2663 | jermar | 71 | if (!ipc_data_read_receive(&callid, NULL)) { |
2625 | jermar | 72 | ipc_answer_0(callid, EINVAL); |
73 | ipc_answer_0(rid, EINVAL); |
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74 | return; |
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75 | } |
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76 | |||
77 | int fs_phone = vfs_grab_phone(file->node->fs_handle); |
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78 | |||
79 | /* |
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80 | * Make a VFS_READ request at the destination FS server. |
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81 | */ |
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82 | aid_t msg; |
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2658 | jermar | 83 | ipc_call_t answer; |
2663 | jermar | 84 | msg = async_send_3(fs_phone, VFS_READ, file->node->dev_handle, |
85 | file->node->index, file->pos, &answer); |
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2625 | jermar | 86 | |
87 | /* |
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2663 | jermar | 88 | * Forward the IPC_M_DATA_READ request to the destination FS server. |
89 | * The call will be routed as if sent by ourselves. Note that call |
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90 | * arguments are immutable in this case so we don't have to bother. |
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2625 | jermar | 91 | */ |
2663 | jermar | 92 | ipc_forward_fast(callid, fs_phone, 0, 0, 0, IPC_FF_ROUTE_FROM_ME); |
2625 | jermar | 93 | |
94 | vfs_release_phone(fs_phone); |
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95 | |||
96 | /* |
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97 | * Wait for reply from the FS server. |
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98 | */ |
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99 | ipcarg_t rc; |
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100 | async_wait_for(msg, &rc); |
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2658 | jermar | 101 | size_t bytes = IPC_GET_ARG1(answer); |
2625 | jermar | 102 | |
103 | /* |
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2659 | jermar | 104 | * Update the position pointer. |
105 | */ |
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106 | file->pos += bytes; |
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107 | |||
108 | /* |
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2625 | jermar | 109 | * FS server's reply is the final result of the whole operation we |
110 | * return to the client. |
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111 | */ |
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2658 | jermar | 112 | ipc_answer_1(rid, rc, bytes); |
2625 | jermar | 113 | } |
114 | |||
115 | /** |
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116 | * @} |
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117 | */ |