ISFS_LoadSuperblock RE

ISFS_LoadSuperblock.c

ISFS_Superblock *ISFS_LoadSuperblock(ISFS *isfs)
{
	if ((isfs->initState & 2) == 0)
		return;

	if ((isfs->initState & 0x44) == 0x44)
		return NULL;

	int latestVersion = 0;
	u32 maxGeneration = 0xffffffff;
	while (true)
	{
		int latestSuperblock = -1;
		int latestGeneration = 0;

		/* Try to load the latest ISFS superblock */
		if (ISFS_InitSizeProperties(isfs, FALSE) != 0)
			return NULL;

		int latestSuperblock = ISFS_FindLatestSuperblock(isfs, FALSE, 0, maxGeneration, 0, &generation, &isfsVersion);
		if (latestSuperblock >= 0)
		{
			isfs->initState &= ~0x20;
			latestVersion = isfsVersion;
			latestGeneration = generation;
			isfs->nextSuperBlock = (latestSuperblock + 1) & ((1 << isfs->superblockCountLog2) - 1U);
		}

		/* Try to load the latest compat ISFS superblock */
		if (ISFS_InitSizeProperties(isfs, TRUE) != 0)
			return NULL;

		int latestComparSuperblock =
			ISFS_FindLatestSuperblock(isfs, TRUE, latestGeneration, maxGeneration, 0, &generation, &isfsVersion);
		if (latestComparSuperblock >= 0)
		{
			isfs->initState |= 0x20;
			latestVersion = isfsVersion;
			latestGeneration = generation;
			isfs->nextSuperBlock = (latestComparSuperblock + 1) & ((1 << isfs->superblockCountLog2) - 1U);
			latestSuperblock = latestComparSuperblock;
		}

		/* Setup size properties according to the current ISFS version */
		int rc = ISFS_InitSizeProperties(isfs, (isfs->initState & 0x20) ? TRUE : FALSE);
		if ((rc != 0) || (latestSuperblock < 0))
			return NULL;

		/* This is a simplification of the many __divdi3 calls.
		* Results should match, but the code differs
		* (isfs->nandBlockSize is also involded, although its value can be simplified away)
		*/
		u32 clustersPerSuperblock = 1 << (isfs->metadataSizeLog2 - isfs->superblockCountLog2 - 0xe);
		u32 dataClusters = (isfs->unkZero2 + isfs->dataAreaSize >> 0xe);
		u32 superblockClusterIndex = dataClusters + latestSuperblock * clustersPerSuperblock;
		u32 superblockClusterCount = 1 << (isfs->metadataSizeLog2 - isfs->superblockCountLog2 - 0xe);

		/* HMAC seed */
		*(u32 *)(isfs->field_0x44040 + 0x10) = superblockClusterIndex;

		rc = ISFS_ReadCluster(isfs, superblockClusterIndex & 0xffff, superblockClusterCount, 2,
							(int)isfs->field_0x44040, &isfs->superblock, NULL);

		/* read successfull */
		if (rc == 0)
			break;

		/* one of the two copies of the hmac hash did not match */
		if (rc == -0x80471)
		{
			needsRepair = true;
			break:
		}

		maxGeneration = latestGeneration;
	}

	if (latestVersion != 0)
	{
		isfs->initState |= 8;
		return NULL;
	}
	else
		isfs->initState &= ~8;

	if (!isfs)
		return NULL;

	isfs->initState |= 4;

	if (needsRepair)
		ISFS_WriteSuperblock(isfs);

	return &isfs->superblock;
}

int ISFS_InitSizeProperties(ISFS *isfs, BOOL isCompat)
{
	isfs->unkZero2 = isfs->unkZero1;
	isfs->superblockCountLog2 = (isCompat) ? 4 : 6;

	if (isfs->nandSizeBytes == 0x4000000)
		isfs->metadataSizeLog2 = isfs->superblockCountLog2 + 0xe;
	else if ((isfs->nandSizeBytes == 0x8000000) || (isfs->nandSizeBytes == 0x10000000))
		isfs->metadataSizeLog2 = isfs->superblockCountLog2 + 0x10;
	else if ((isfs->nandSizeBytes == 0x20000000) || (isfs->nandSizeBytes == 0x40000000))
		isfs->metadataSizeLog2 = isfs->superblockCountLog2 + 0x12;
	else
		return -0x80480;

	u32 sizeOfSuperblock = 1 << (isfs->metadataSizeLog2 - isfs->superblockCountLog2);
	if (sizeOfSuperblock > 0x40000)
		return -0x80480;

	isfs->dataAreaSize = (isfs->nandSizeBytes - isfs->unkZero2) - (1 << isfs->metadataSizeLog2);
	isfs->initState = isfs->initState | 0x40;
	return 0;
}

u32 ISFS_FindLatestSuperblock(ISFS *isfs, BOOL isCompat, u32 minGeneration, u32 maxGeneration, u32 unkFieldCheck,
							u32 *outGeneration, u32 *outIsfsVersion)
{
	*outGeneration = 0;
	*outIsfsVersion = 0;

	int lastValidSuperblock = -1;
	for (u32 superblockIndex = 0; superblockIndex < (1 << isfs->superblockCountLog2); superblockIndex++)
	{
		/* This is a simplification of the many __divdi3 calls.
		* Results should match, but the code differs
		* (isfs->nandBlockSize is also involded, although its value can be simplified away)
		*/
		u32 clustersPerSuperblock = 1 << (isfs->metadataSizeLog2 - isfs->superblockCountLog2 - 0xe);
		u32 dataClusters = (isfs->unkZero2 + isfs->dataAreaSize >> 0xe);
		u32 superblockClusterIndex = dataClusters + superblockIndex * clustersPerSuperblock;

		int rc = ISFS_ReadCluster(isfs, superblockClusterIndex, 1, 0, 0, &isfs->superblock, NULL);
		if ((rc != 0) && (rc != -0x80471))
			continue;

		u32 isfsVersion;
		if (!isCompat && ((isfs->super.magic & 0xffffff0f) == 0x53465301))
			isfsVersion = ((isfs->super.magic >> 4) == 2) ? 0 : 1;
		else if (isfs->super.magic == 0x53464653)
			isfsVersion = 0;
		else
			continue;

		if (unkFieldCheck > (isfs->super.unkFieldCheck + 1))
			continue;
		if (unkFieldCheck > isfs->super.unkFieldCheck)
			isfs->super.unkFieldCheck = unkFieldCheck;

		if (isfs->super.generation < minGeneration)
			continue;
		if (isfs->super.generation >= maxGeneration)
			continue;

		if (isfs->super.generation < *outGeneration)
			continue;

		*outGeneration = isfs->super.generation;
		*outIsfsVersion = isfsVersion;
		lastValidSuperblock = superblockIndex;
	}

	return lastValidSuperblock;
}