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 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 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
