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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2368 | konopa | 1 | /* This file contains the procedures that manipulate file descriptors. */ |
| 2 | |||
| 3 | /* |
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| 4 | * Methods: |
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| 5 | * get_fd: look for free file descriptor and free filp slots |
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| 6 | * get_filp: look up the filp entry for a given file descriptor |
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| 7 | * find_filp: find a filp slot that points to a given inode |
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| 8 | */ |
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| 9 | |||
| 10 | |||
| 11 | #include "fs.h" |
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| 12 | #include "file.h" |
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| 13 | #include "fproc.h" |
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| 14 | #include "inode.h" |
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| 15 | |||
| 16 | |||
| 17 | int get_fd(int start, int *k, filp_t **fpt) |
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| 18 | { |
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| 19 | /* Look for a free file descriptor and a free filp slot. */ |
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| 20 | |||
| 21 | register filp_t *f; |
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| 22 | register int i; |
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| 23 | |||
| 24 | *k = -1; /* we need a way to tell if file desc found */ |
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| 25 | |||
| 26 | /* Search the fproc fp_filp table for a free file descriptor. */ |
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| 27 | for (i = start; i < OPEN_MAX; i++) { |
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| 28 | if (fp->fp_filp[i] == NIL_FILP) { |
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| 29 | /* A file descriptor has been located. */ |
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| 30 | *k = i; |
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| 31 | break; |
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| 32 | } |
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| 33 | } |
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| 34 | |||
| 35 | /* Check to see if a file descriptor has been found. */ |
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| 36 | if (*k < 0) |
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| 37 | return FS_EMFILE; /* this is why we initialized k to -1 */ |
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| 38 | |||
| 39 | /* Now that a file descriptor has been found, look for a free filp slot. */ |
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| 40 | for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
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| 41 | if (f->filp_count == 0) { |
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| 42 | f->filp_mode = R_BIT; |
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| 43 | f->filp_pos = 0L; |
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| 44 | f->filp_flags = 0; |
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| 45 | *fpt = f; |
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| 46 | return OK; |
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| 47 | } |
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| 48 | } |
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| 49 | |||
| 50 | /* If control passes here, the filp table must be full. Report that back. */ |
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| 51 | return FS_ENFILE; |
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| 52 | } |
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| 53 | |||
| 54 | |||
| 55 | filp_t *get_filp(int fild) |
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| 56 | { |
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| 57 | |||
| 58 | /* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */ |
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| 59 | |||
| 60 | err_code = FS_EBADF; |
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| 61 | if (fild < 0 || fild >= OPEN_MAX ) |
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| 62 | return NIL_FILP; |
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| 63 | |||
| 64 | return(fp->fp_filp[fild]); /* may also be NIL_FILP */ |
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| 65 | } |
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| 66 | |||
| 67 | |||
| 68 | filp_t *find_filp(register inode_t *rip) |
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| 69 | { |
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| 70 | |||
| 71 | /* Find a filp slot that refers to the inode 'rip' in a way as described. |
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| 72 | * Used for determining whether somebody is still interested in. |
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| 73 | * Like 'get_fd' it performs its job by linear search through the filp table. |
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| 74 | */ |
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| 75 | |||
| 76 | register filp_t *f; |
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| 77 | |||
| 78 | for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
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| 79 | if (f->filp_count != 0 && f->filp_ino == rip){ |
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| 80 | return f; |
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| 81 | } |
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| 82 | } |
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| 83 | |||
| 84 | /* If control passes here, the filp wasn't there. Report that back. */ |
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| 85 | return NIL_FILP; |
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| 86 | } |
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| 87 |