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
22void *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
54void 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