1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
8 * Boston MA 02111-1307, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
10 *
11 * ----------------------------------------------------------------------- */
12
13 /*
14 * cache.c
15 *
16 * Simple sector cache
17 */
18
19 #include <stdlib.h>
20 #include "libfatint.h"
21
libfat_get_sector(struct libfat_filesystem * fs,libfat_sector_t n)22 void *libfat_get_sector(struct libfat_filesystem *fs, libfat_sector_t n)
23 {
24 struct libfat_sector *ls;
25
26 for (ls = fs->sectors; ls; ls = ls->next) {
27 if (ls->n == n)
28 return ls->data; /* Found in cache */
29 }
30
31 /* Not found in cache */
32 ls = malloc(sizeof(struct libfat_sector));
33 if (!ls) {
34 libfat_flush(fs);
35 ls = malloc(sizeof(struct libfat_sector));
36
37 if (!ls)
38 return NULL; /* Can't allocate memory */
39 }
40
41 if (fs->read(fs->readptr, ls->data, LIBFAT_SECTOR_SIZE, n)
42 != LIBFAT_SECTOR_SIZE) {
43 free(ls);
44 return NULL; /* I/O error */
45 }
46
47 ls->n = n;
48 ls->next = fs->sectors;
49 fs->sectors = ls;
50
51 return ls->data;
52 }
53
libfat_flush(struct libfat_filesystem * fs)54 void libfat_flush(struct libfat_filesystem *fs)
55 {
56 struct libfat_sector *ls, *lsnext;
57
58 lsnext = fs->sectors;
59 fs->sectors = NULL;
60
61 for (ls = lsnext; ls; ls = lsnext) {
62 lsnext = ls->next;
63 free(ls);
64 }
65 }
66