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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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| 35 | |||
| 36 | |||
| 2368 | konopa | 37 | /* This file contains the procedures that manipulate file descriptors. */ |
| 38 | |||
| 39 | /* |
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| 40 | * Methods: |
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| 41 | * get_fd: look for free file descriptor and free filp slots |
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| 42 | * get_filp: look up the filp entry for a given file descriptor |
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| 43 | * find_filp: find a filp slot that points to a given inode |
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| 44 | */ |
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| 45 | |||
| 46 | |||
| 47 | #include "fs.h" |
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| 48 | #include "file.h" |
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| 49 | #include "fproc.h" |
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| 50 | #include "inode.h" |
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| 51 | |||
| 52 | |||
| 53 | int get_fd(int start, int *k, filp_t **fpt) |
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| 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 | |||
| 90 | |||
| 91 | filp_t *get_filp(int fild) |
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| 92 | { |
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| 93 | |||
| 94 | /* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */ |
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| 95 | |||
| 96 | err_code = FS_EBADF; |
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| 97 | if (fild < 0 || fild >= OPEN_MAX ) |
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| 98 | return NIL_FILP; |
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| 99 | |||
| 100 | return(fp->fp_filp[fild]); /* may also be NIL_FILP */ |
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| 101 | } |
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| 102 | |||
| 103 | |||
| 104 | filp_t *find_filp(register inode_t *rip) |
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| 105 | { |
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| 106 | |||
| 107 | /* Find a filp slot that refers to the inode 'rip' in a way as described. |
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| 108 | * Used for determining whether somebody is still interested in. |
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| 109 | * Like 'get_fd' it performs its job by linear search through the filp table. |
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| 110 | */ |
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| 111 | |||
| 112 | register filp_t *f; |
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| 113 | |||
| 114 | for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
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| 115 | if (f->filp_count != 0 && f->filp_ino == rip){ |
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| 116 | return f; |
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| 117 | } |
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| 118 | } |
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| 119 | |||
| 120 | /* If control passes here, the filp wasn't there. Report that back. */ |
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| 121 | return NIL_FILP; |
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| 122 | } |
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| 123 |