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2404 | konopa | 1 | /* |
2 | * Copyright (c) 1987,1997, Prentice Hall |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use of the MINIX operating system in source and |
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6 | * binary forms, with or without modification, are permitted provided |
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7 | * that the following conditions are met: |
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8 | |||
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 | |||
12 | * - Redistributions in binary form must reproduce the above |
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13 | * copyright notice, this list of conditions and the following |
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14 | * disclaimer in the documentation and/or other materials provided |
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15 | * with the distribution. |
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16 | |||
17 | * - Neither the name of Prentice Hall nor the names of the software |
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18 | * authors or contributors may be used to endorse or promote |
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19 | * products derived from this software without specific prior |
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20 | * written permission. |
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21 | |||
22 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS, AUTHORS, AND |
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23 | * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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24 | * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
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25 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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26 | * IN NO EVENT SHALL PRENTICE HALL OR ANY AUTHORS OR CONTRIBUTORS BE |
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27 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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28 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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29 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
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30 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
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31 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE |
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32 | * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, |
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33 | * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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34 | */ |
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2435 | jelen | 35 | |
36 | /** @addtogroup FileSystemImpl |
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37 | * @{ |
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38 | */ |
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2404 | konopa | 39 | |
2435 | jelen | 40 | /** |
41 | * @file filedesc.c |
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42 | * @brief This file contains the procedures that manipulate file descriptors. |
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2368 | konopa | 43 | */ |
44 | |||
45 | #include "fs.h" |
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46 | #include "file.h" |
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47 | #include "fproc.h" |
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48 | #include "inode.h" |
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49 | |||
2435 | jelen | 50 | /** |
51 | * Look for free file descriptor and free filp slots |
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52 | */ |
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2368 | konopa | 53 | int get_fd(int start, int *k, filp_t **fpt) |
54 | { |
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55 | /* Look for a free file descriptor and a free filp slot. */ |
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56 | |||
57 | register filp_t *f; |
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58 | register int i; |
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59 | |||
60 | *k = -1; /* we need a way to tell if file desc found */ |
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61 | |||
62 | /* Search the fproc fp_filp table for a free file descriptor. */ |
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63 | for (i = start; i < OPEN_MAX; i++) { |
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64 | if (fp->fp_filp[i] == NIL_FILP) { |
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65 | /* A file descriptor has been located. */ |
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66 | *k = i; |
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67 | break; |
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68 | } |
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69 | } |
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70 | |||
71 | /* Check to see if a file descriptor has been found. */ |
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72 | if (*k < 0) |
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73 | return FS_EMFILE; /* this is why we initialized k to -1 */ |
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74 | |||
75 | /* Now that a file descriptor has been found, look for a free filp slot. */ |
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76 | for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
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77 | if (f->filp_count == 0) { |
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78 | f->filp_mode = R_BIT; |
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79 | f->filp_pos = 0L; |
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80 | f->filp_flags = 0; |
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81 | *fpt = f; |
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82 | return OK; |
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83 | } |
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84 | } |
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85 | |||
86 | /* If control passes here, the filp table must be full. Report that back. */ |
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87 | return FS_ENFILE; |
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88 | } |
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89 | |||
2435 | jelen | 90 | /** |
91 | * Look up the filp entry for a given file descriptor |
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92 | */ |
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2368 | konopa | 93 | filp_t *get_filp(int fild) |
94 | { |
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95 | |||
96 | /* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */ |
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97 | |||
98 | err_code = FS_EBADF; |
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99 | if (fild < 0 || fild >= OPEN_MAX ) |
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100 | return NIL_FILP; |
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101 | |||
102 | return(fp->fp_filp[fild]); /* may also be NIL_FILP */ |
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103 | } |
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104 | |||
105 | |||
2435 | jelen | 106 | /** |
107 | * Find a filp slot that points to a given inode |
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108 | */ |
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2368 | konopa | 109 | filp_t *find_filp(register inode_t *rip) |
110 | { |
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111 | |||
112 | /* Find a filp slot that refers to the inode 'rip' in a way as described. |
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113 | * Used for determining whether somebody is still interested in. |
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114 | * Like 'get_fd' it performs its job by linear search through the filp table. |
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115 | */ |
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116 | |||
117 | register filp_t *f; |
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118 | |||
119 | for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
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120 | if (f->filp_count != 0 && f->filp_ino == rip){ |
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121 | return f; |
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122 | } |
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123 | } |
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124 | |||
125 | /* If control passes here, the filp wasn't there. Report that back. */ |
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126 | return NIL_FILP; |
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127 | } |
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128 | |||
2435 | jelen | 129 | |
130 | /** |
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131 | * } |
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132 | */ |
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133 |