usbloadergx/source/fatmounter.c

#include <fat.h>
#include <string.h>
#include <sys/dir.h>
#include <sys/iosupport.h>
#include <ogc/lwp_watchdog.h>
#include <ogc/mutex.h>
#include <ogc/system.h>
#include <ogc/usbstorage.h>
#include <sdcard/wiisd_io.h>

//these are the only stable and speed is good
#define CACHE 8
#define SECTORS 64

enum BPB {
	BPB_jmpBoot = 0x00,
	BPB_OEMName = 0x03,
	// BIOS Parameter Block
	BPB_bytesPerSector = 0x0B,
	BPB_sectorsPerCluster = 0x0D,
	BPB_reservedSectors = 0x0E,
	BPB_numFATs = 0x10,
	BPB_rootEntries = 0x11,
	BPB_numSectorsSmall = 0x13,
	BPB_mediaDesc = 0x15,
	BPB_sectorsPerFAT = 0x16,
	BPB_sectorsPerTrk = 0x18,
	BPB_numHeads = 0x1A,
	BPB_numHiddenSectors = 0x1C,
	BPB_numSectors = 0x20,
	// Ext BIOS Parameter Block for FAT16
	BPB_FAT16_driveNumber = 0x24,
	BPB_FAT16_reserved1 = 0x25,
	BPB_FAT16_extBootSig = 0x26,
	BPB_FAT16_volumeID = 0x27,
	BPB_FAT16_volumeLabel = 0x2B,
	BPB_FAT16_fileSysType = 0x36,
	// Bootcode
	BPB_FAT16_bootCode = 0x3E,
	// FAT32 extended block
	BPB_FAT32_sectorsPerFAT32 = 0x24,
	BPB_FAT32_extFlags = 0x28,
	BPB_FAT32_fsVer = 0x2A,
	BPB_FAT32_rootClus = 0x2C,
	BPB_FAT32_fsInfo = 0x30,
	BPB_FAT32_bkBootSec = 0x32,
	// Ext BIOS Parameter Block for FAT32
	BPB_FAT32_driveNumber = 0x40,
	BPB_FAT32_reserved1 = 0x41,
	BPB_FAT32_extBootSig = 0x42,
	BPB_FAT32_volumeID = 0x43,
	BPB_FAT32_volumeLabel = 0x47,
	BPB_FAT32_fileSysType = 0x52,
	// Bootcode
	BPB_FAT32_bootCode = 0x5A,
	BPB_bootSig_55 = 0x1FE,
	BPB_bootSig_AA = 0x1FF
};

static const char FAT_SIG[3] = {'F', 'A', 'T'};

#define BYTES_PER_READ 512

static bool _FAT_partition_isFAT(const DISC_INTERFACE* disc, sec_t startSector)
{
	uint8_t sectorBuffer[BYTES_PER_READ] = {0};
	if (!disc->readSectors(startSector, 1, sectorBuffer)) {
			return false;
	}
	// Make sure it is a valid BPB
	if ( (sectorBuffer[BPB_bootSig_55] != 0x55) || (sectorBuffer[BPB_bootSig_AA] != 0xAA)) {
		return false;
	}

	// Now verify that this is indeed a FAT partition
	if (memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) && 
		memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
	{
		return false;
	}

	// check again for the last two cases to make sure that we really have a FAT filesystem here
	// and won't corrupt any data
	if(memcmp(sectorBuffer + BPB_FAT16_fileSysType, "FAT", 3) != 0 && memcmp(sectorBuffer + BPB_FAT32_fileSysType, "FAT32", 5) != 0)
	{
		return false;
	}
	return true;
}
static inline uint32_t u8array_to_u32 (const uint8_t* item, int offset) {
	return ( item[offset] | (item[offset + 1] << 8) | (item[offset + 2] << 16) | (item[offset + 3] << 24));
}

sec_t GetFATPartition(const DISC_INTERFACE* disc)
{
	int i;
	uint8_t sectorBuffer[BYTES_PER_READ] = {0};
	sec_t startSector = 0;
	
	if(!disc->startup())
		return 0;

	// Read first sector of disc
	if (!disc->readSectors(0, 1, sectorBuffer))
		startSector = 0;

	// Make sure it is a valid MBR or boot sector
	if ( (sectorBuffer[BPB_bootSig_55] != 0x55) || (sectorBuffer[BPB_bootSig_AA] != 0xAA))
		startSector = 0;

	if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
	{
		// Check if there is a FAT string, which indicates this is a boot sector
		startSector = 0;
	}
	else if (!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
	{
		// Check for FAT32
		startSector = 0;
	}
	else
	{
		// This is an MBR
		// Find first valid partition from MBR
		// First check for an active partition
		for (i=0x1BE; (i < 0x1FE) && (sectorBuffer[i] != 0x80); i+= 0x10);
		// If it find an active partition, check for FAT-Partition
		if ( i != 0x1FE && !_FAT_partition_isFAT(disc, u8array_to_u32(sectorBuffer, 0x8 + i)) )
			i = 0x1FE;

		// If it didn't find an active partition, search for any valid partition
		if (i == 0x1FE)
		{
			for (i=0x1BE; i < 0x1FE; i+= 0x10)
			{
				if ( sectorBuffer[i+0x04] != 0x00 && _FAT_partition_isFAT(disc, u8array_to_u32(sectorBuffer, 0x8 + i)) )
					break;
			}
		}
		if (i != 0x1FE)
			startSector = u8array_to_u32(sectorBuffer, 0x8 + i);;
	}
	disc->shutdown();
	return startSector;
}

int USBDevice_Init()
{
	//closing all open Files write back the cache and then shutdown em!
	fatUnmount("USB:/");
	//right now mounts first FAT-partition
	if (fatMount("USB", &__io_usbstorage, GetFATPartition(&__io_usbstorage), CACHE, SECTORS)) {
		//try first mount with libogc
		return 1;
	}
	return -1;
}

void USBDevice_deInit()
{
	//closing all open Files write back the cache and then shutdown em!
	fatUnmount("USB:/");
}

int isSdInserted()
{
    return __io_wiisd.isInserted();
}

int SDCard_Init()
{
	//closing all open Files write back the cache and then shutdown em!
	fatUnmount("SD:/");
	//right now mounts first FAT-partition
	if (fatMount("SD", &__io_wiisd, GetFATPartition(&__io_wiisd), CACHE, SECTORS))
		return 1;
	return -1;
}

void SDCard_deInit()
{
	//closing all open Files write back the cache and then shutdown em!
	fatUnmount("SD:/");
}