From ccc47d5bf2c28e40857912b7c65e3f97415ebe7a Mon Sep 17 00:00:00 2001
From: Christophe Grenier <grenier@cgsecurity.org>
Date: Sun, 8 Dec 2013 14:40:15 +0100
Subject: [PATCH] fat32_get_free_count() and fat32_get_next_free() - code style

---
 src/fat.c |  6 ++++--
 src/fat.h | 10 ++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/fat.c b/src/fat.c
index aea54079..c64cfb61 100644
--- a/src/fat.c
+++ b/src/fat.c
@@ -747,12 +747,14 @@ int comp_FAT(disk_t *disk, const partition_t *partition, const unsigned long int
 
 unsigned long int fat32_get_free_count(const unsigned char *boot_fat32, const unsigned int sector_size)
 {
-  return (boot_fat32[sector_size+0x1E8+3]<<24)+(boot_fat32[sector_size+0x1E8+2]<<16)+(boot_fat32[sector_size+0x1E8+1]<<8)+boot_fat32[sector_size+0x1E8];
+  const struct fat_fsinfo *fsinfo=(const struct fat_fsinfo *)&boot_fat32[sector_size];
+  return le32(fsinfo->freecnt);
 }
 
 unsigned long int fat32_get_next_free(const unsigned char *boot_fat32, const unsigned int sector_size)
 {
-  return (boot_fat32[sector_size+0x1EC+3]<<24)+(boot_fat32[sector_size+0x1EC+2]<<16)+(boot_fat32[sector_size+0x1EC+1]<<8)+boot_fat32[sector_size+0x1EC];
+  const struct fat_fsinfo *fsinfo=(const struct fat_fsinfo *)&boot_fat32[sector_size];
+  return le32(fsinfo->nextfree);
 }
 
 int recover_FAT(disk_t *disk_car, const struct fat_boot_sector*fat_header, partition_t *partition, const int verbose, const int dump_ind, const int backup)
diff --git a/src/fat.h b/src/fat.h
index 935e9916..f15d6684 100644
--- a/src/fat.h
+++ b/src/fat.h
@@ -75,6 +75,16 @@ struct fat_boot_sector {
 	uint16_t	marker;
 } __attribute__ ((__packed__));
 
+struct fat_fsinfo {
+  uint32_t leadsig;		/* 0x41615252 */
+  uint8_t reserved1[480];
+  uint32_t strucsig;		/* 0x61417272 */
+  uint32_t freecnt;     	/* free clusters 0xfffffffff if unknown */
+  uint32_t nextfree;		/* next free cluster */
+  uint8_t reserved3[12];
+  uint32_t magic3;		/* 0xAA550000 */
+} __attribute__ ((__packed__));
+
 struct msdos_dir_entry {
 	int8_t	name[8],ext[3];		/* 00 name and extension */
 	uint8_t	attr;			/* 0B attribute bits */