iris/source/fat.ccp

#pypp 0
#include <iris.hh>
#include <devices.hh>

#define SECTOR_BITS 9
#define BLOCK_MASK (~((1 << SECTOR_BITS) - 1))
#define ROOT_CLUSTER 0x7fffffff

static unsigned _free
extern unsigned _end

void init_alloc ():
	_free = ((unsigned)&_end + PAGE_SIZE - 1) & PAGE_MASK

char *alloc_space (unsigned pages):
	unsigned ret = (_free + PAGE_SIZE - 1) & PAGE_MASK
	_free = ret + (pages << PAGE_BITS)
	return (char *)ret

void *operator new[] (unsigned size):
	//kdebug ("new ")
	void *ret = (void *)_free
	size = (size + 3) & ~3
	unsigned rest = PAGE_SIZE - (((_free - 1) & ~PAGE_MASK) + 1)
	if rest < size:
		unsigned pages = ((size - rest) + PAGE_SIZE - 1) >> PAGE_BITS
		for unsigned p = 0; p < pages; ++p:
			Iris::Page page = Iris::my_memory.create_page ()
			page.set_flags (Iris::Page::PAYING | Iris::Page::FRAME, Iris::Page::PAYING | Iris::Page::FRAME)
			Iris::my_memory.map (page, _free + rest + (p << PAGE_BITS))
			Iris::free_cap (page)
	_free += size
	//kdebug_num ((unsigned)ret)
	//kdebug ("+")
	//kdebug_num (size)
	//kdebug ("\n")
	return ret

void *operator new (unsigned size):
	return new char[size]

static Iris::WString dev
static Iris::Num device_size
static Iris::Page page
static char *data
static Iris::Num current_block
static void read_block (Iris::Num idx, Iris::Page p = page, unsigned size = 1 << SECTOR_BITS, unsigned offset = 0):
	if p.code == page.code:
		if idx.value () == current_block.value () && offset == 0 && size == 1 << SECTOR_BITS:
			return
		current_block = idx
	//kdebug ("fat getting block: ")
	//kdebug_num (idx.h)
	//kdebug (":")
	//kdebug_num (idx.l)
	//kdebug ("+")
	//kdebug_num (size)
	//kdebug ("@")
	//kdebug_num (offset)
	//kdebug ("\n")
	dev.get_block (idx, size, offset, p)

struct Fat:
	char oem[8]
	unsigned sector_size_bits
	unsigned sectors_per_cluster_bits
	unsigned reserved_sectors
	unsigned num_fats
	unsigned root_entries
	unsigned sectors
	unsigned media
	unsigned sectors_per_fat
	unsigned sectors_per_track
	unsigned heads
	unsigned hidden_sectors
	unsigned active_fat
	bool write_all_fats
	unsigned fs_version
	unsigned root_cluster
	unsigned fsinfo_sector
	unsigned boot_backup_sector
	unsigned drive
	unsigned current_head
	unsigned volume_id
	char label[0xb]

	unsigned bits
	unsigned clusters
	unsigned cluster_size_bits
	unsigned root_sectors
	unsigned header_sectors
	unsigned bad_clusters

	unsigned free_clusters
	unsigned last_alloced

	unsigned *fat
	unsigned first_free_cluster, first_bad_cluster

	void print_num (char const *pre, unsigned data):
		kdebug ("\t")
		kdebug (pre)
		unsigned bytes = 1
		while bytes < 8 && data >> (bytes * 4):
			++bytes
		kdebug_num (data, bytes)
		kdebug ("\n")

	void print_br ():
		kdebug ("\tOEM: '")
		for unsigned i = 0; i < 8; ++i:
			kdebug_char (oem[i])
		kdebug ("'\n")
		print_num ("bytes per sector: ", 1 << sector_size_bits)
		print_num ("sectors per cluster: ", 1 << sectors_per_cluster_bits)
		print_num ("reserved sectors: ", reserved_sectors)
		print_num ("number of fats: ", num_fats)
		print_num ("entries in root directory: ", root_entries)
		print_num ("sectors: ", sectors)
		print_num ("media descriptor: ", media)
		print_num ("sectors per fat: ", sectors_per_fat)
		print_num ("sectors per track: ", sectors_per_track)
		print_num ("heads: ", heads)
		print_num ("hidden sectors: ", hidden_sectors)
		print_num ("active_fat: ", active_fat)
		kdebug ("\twrite all: ")
		kdebug (write_all_fats ? "yes\n" : "no\n")
		print_num ("fs version: ", fs_version)
		print_num ("root cluster: ", root_cluster)
		print_num ("fsinfo sector: ", fsinfo_sector)
		print_num ("boot sector backup sector: ", boot_backup_sector)
		print_num ("drive: ", drive)
		print_num ("current head: ", current_head)
		print_num ("volume id: ", volume_id)
		kdebug ("\tlabel: '")
		for unsigned i = 0; i < 0xb; ++i:
			kdebug_char (label[i])
		kdebug ("'\n")
		print_num ("bits: ", bits)
		print_num ("clusters: ", clusters)
		print_num ("header sectors: ", header_sectors)

	unsigned read_num (char *data, unsigned bytes):
		unsigned ret = 0
		for unsigned i = 0; i < bytes; ++i:
			ret |= (data[i] & 0xff) << (i * 8)
		return ret

	void map_fat_cluster (unsigned c, unsigned offset = 0):
		read_block ((hidden_sectors + reserved_sectors + ((c * bits + 8 * offset) >> (sector_size_bits + 3))) << sector_size_bits)
	
	unsigned make_bits (unsigned orig):
		unsigned ret
		for ret = 0; ret < 32; ++ret:
			if orig == 1 << ret:
				return ret
		Iris::panic (ret, "non-power of 2")
		return ret

	void reset ():
		read_block (0)
		if data[0x1fe] != 0x55 || (data[0x1ff] & 0xff) != 0xaa:
			kdebug ("invalid boot record signature in fat device\n")
		for unsigned i = 0; i < 8; ++i:
			oem[i] = data[3 + i]
		sector_size_bits = make_bits (read_num (data + 0xb, 2))
		sectors_per_cluster_bits = make_bits (read_num (data + 0xd, 1))
		cluster_size_bits = sector_size_bits + sectors_per_cluster_bits
		reserved_sectors = read_num (data + 0xe, 2)
		num_fats = read_num (data + 0x10, 1)
		root_entries = read_num (data + 0x11, 2)
		sectors = read_num (data + 0x13, 2)
		media = read_num (data + 0x15, 1)
		sectors_per_fat = read_num (data + 0x16, 2)
		sectors_per_track = read_num (data + 0x18, 2)
		heads = read_num (data + 0x1a, 2)
		hidden_sectors = read_num (data + 0x1c, 4)
		if !sectors:
			sectors = read_num (data + 0x20, 4)
		if Iris::Num (sectors).value () << sector_size_bits > device_size.value ():
			sectors = device_size.value () >> sector_size_bits
			kdebug ("warning: limiting sectors because of limited device size\n")

		root_sectors = (root_entries * 32 + (1 << sector_size_bits) - 1) >> sector_size_bits
		header_sectors = hidden_sectors + reserved_sectors + sectors_per_fat * num_fats + root_sectors
		clusters = (sectors - header_sectors) >> sectors_per_cluster_bits
		unsigned skip
		if clusters >= 65525:
			bits = 32
			sectors_per_fat = read_num (data + 0x24, 4)
			active_fat = read_num (data + 0x28, 2)
			write_all_fats = active_fat & 0x80
			active_fat &= 0xf
			fs_version = read_num (data + 0x2a, 2)
			root_cluster = read_num (data + 0x2c, 4)
			fsinfo_sector = read_num (data + 0x30, 2)
			boot_backup_sector = read_num (data + 0x32, 2)
			skip = 0x40 - 0x24
		else:
			if clusters < 4085:
				bits = 12
			else:
				bits = 16
			skip = 0
			active_fat = 0
			write_all_fats = true
			fs_version = 0
			root_cluster = 0
			fsinfo_sector = 0
			boot_backup_sector = 0
		unsigned fat_entries_per_sector = (8 << sector_size_bits) / bits
		unsigned fat_entries = sectors_per_fat * fat_entries_per_sector
		if clusters + 2 > fat_entries:
			clusters = fat_entries - 2
			kdebug ("warning: limiting clusters because of limited sector count\n")
		drive = read_num (data + skip + 0x24, 1)
		current_head = read_num (data + skip + 0x25, 1)
		if data[skip + 0x26] == 0x29:
			volume_id = read_num (data + skip + 0x27, 4)
			for unsigned i = 0; i < 0xb; ++i:
				label[i] = data[skip + 0x2b + i]
			char *id = data + skip + 0x36
			if id[0] != 'F' || id[1] != 'A' || id[2] != 'T' || id[5] != ' ' || id[6] != ' ' || id[7] != ' ':
				kdebug ("warning: file system type field was not 'FATxx   '\n")
			else:
				switch bits:
					case 12:
						if id[3] != '1' || id[4] != '2':
							kdebug ("warning: id for fat12 is not FAT12\n")
						break
					case 16:
						if id[3] != '1' || id[4] != '6':
							kdebug ("warning: id for fat16 is not FAT16\n")
						break
					case 32:
						if id[3] != '3' || id[4] != '2':
							kdebug ("warning: id for fat32 wat not FAT32")
						break
		else:
			volume_id = 0
			for unsigned i = 0; i < 0xb; ++i:
				label[i] = 0
		if fsinfo_sector:
			read_block (fsinfo_sector << sector_size_bits)
			if (data[0] & 0xff) != 0x52 || (data[1] & 0xff) != 0x52 || (data[2] & 0xff) != 0x6a || (data[3] & 0xff) != 0x41 || (data[0x1e4] & 0xff) != 0x72 || (data[0x1e5] & 0xff) != 0x72 || (data[0x1e6] & 0xff) != 0x4a || (data[0x1e7] & 0xff) != 0x61 || (data[0x1fe] & 0xff) != 0x55 || (data[0x1ff] & 0xff) != 0xaa:
				kdebug ("invalid signature in fsinfo structure\n")
			free_clusters = read_num (data + 0x1e8, 4)
			last_alloced = read_num (data + 0x1ec, 4)
		else:
			free_clusters = ~0
			last_alloced = ~0

		// Now read the FAT.
		bad_clusters = 0
		fat = new unsigned[clusters]
		unsigned counted_free_clusters = 0
		for unsigned c = 0; c < clusters; ++c:
			// reduced cluster.
			unsigned rc = c & (1 << sector_size_bits) - 1
			// The next line does nothing most of the time.
			map_fat_cluster (c)
			switch bits:
				case 12:
					fat[c] = data[(rc + 2) * 2] & 0xff
					// There may be a sector boundary in the middle of the entry, so optionally reread.
					map_fat_cluster (c, 1)
					fat[c] |= (data[(rc + 2) * 2 + 1] & 0xff) << 8
					if c & 1:
						fat[c] >>= 4
					else:
						fat[c] &= 0xfff
					break
				case 16:
					fat[c] = read_num (data + (rc + 2) * 2, 2)
					break
				case 32:
					fat[c] = read_num (data + (rc + 2) * 4, 4)
					break
			// Correct for the crazy +2 offset, and keep a list of bad and free clusters.
			if fat[c] == 0:
				// Free cluster.
				fat[c] = first_free_cluster
				first_free_cluster = c
				++counted_free_clusters
			else if fat[c] == 1:
				// Invalid value.
				Iris::panic (0, "entry is '1' in fat.")
			else if bits == 12 && fat[c] == 0xfff || bits == 16 && fat[c] == 0xffff || bits == 32 && fat[c] == 0xfffffff:
				// Last cluster in chain.
				fat[c] = ~0
			else if bits == 12 && fat[c] == 0xff7 || bits == 16 && fat[c] == 0xfff7 || bits == 32 && fat[c] == 0xffffff7:
				// Bad cluster.
				fat[c] = first_bad_cluster
				first_bad_cluster = c
				++bad_clusters
			else:
				// Non-last cluster in chain.
				fat[c] -= 2
	unsigned fat_lookup (unsigned first_cluster, unsigned cluster):
		while cluster--:
			first_cluster = fat[first_cluster]
			if first_cluster == ~0:
				kdebug ("sector beyond end of file requested\n")
				return ~0
		return first_cluster
	struct File:
		Fat *fat
		unsigned size
		unsigned first_cluster
		char name[11]
		bool archive, readonly, system, hidden, directory, volume
		unsigned create_second, create_minute_hour, create_date, access_date, time, date
		void load_cluster (unsigned idx, Iris::Page p = page, unsigned offset = 0):
			unsigned cluster = fat->fat_lookup (first_cluster, idx >> fat->cluster_size_bits)
			kdebug ("loading cluster ")
			kdebug_num (idx)
			kdebug ("@")
			kdebug_num (cluster)
			kdebug (" from file\n")
			if cluster == ~0:
				kdebug ("invalid cluster requested from file\n")
				return
			read_block ((fat->header_sectors + (Iris::Num (cluster).value () << fat->sectors_per_cluster_bits)) << fat->sector_size_bits, p, 1 << fat->cluster_size_bits, offset)
			kdebug ("sector ")
			kdebug_num (fat->header_sectors + (Iris::Num (cluster).value () << fat->sectors_per_cluster_bits))
			kdebug ("\n")
	void get_dir_entry (unsigned dir, unsigned idx, File *f):
		f->fat = this
		unsigned sector = idx >> (sector_size_bits - 5)
		unsigned num = (idx << 5) & ~BLOCK_MASK
		Iris::Num hwsector
		if dir == ROOT_CLUSTER:
			if sector < root_sectors:
				hwsector = header_sectors - root_sectors + sector
			else:
				hwsector = ~0
		else:
			unsigned entry = fat_lookup (dir, sector)
			if entry == ~0:
				hwsector = ~0
			else:
				hwsector = header_sectors + (Iris::Num (entry).value () << sectors_per_cluster_bits)
		if hwsector.value () == ~0:
			kdebug ("invalid sector requested from directory\n")
			f->first_cluster = ~0
			return
		read_block (hwsector.value () << sector_size_bits)
		char *e = &data[num]
		for unsigned i = 0; i < 11; ++i:
			f->name[i] = e[i]
		f->archive = e[0xb] & 0x20
		f->readonly = e[0xb] & 0x10
		f->system = e[0xb] & 0x8
		f->hidden = e[0xb] & 0x4
		f->directory = e[0xb] & 0x2
		f->volume = e[0xb] & 0x1
		f->create_second = read_num (e + 0xd, 1)
		f->create_minute_hour = read_num (e + 0xe, 2)
		f->create_date = read_num (e + 0x10, 2)
		f->access_date = read_num (e + 0x12, 2)
		f->time = read_num (e + 0x16, 1)
		f->date = read_num (e + 0x18, 1)
		f->size = read_num (e + 0x1c, 4)
		f->first_cluster = (read_num (e + 0x14, 2) << 16 | read_num (e + 0x1a, 2)) - 2

// Capability encoding.
// 0:ROOT_CLUSTER = non fat-32 root directory.
// 0:cluster = other directory.
// cluster:index = file index from directory at cluster.
// cluster|0x80000000:index = filename for file with index from directory at cluster.

Iris::Num start ():
	init_alloc ()
	current_block = ~0
	dev = Iris::my_parent.get_capability <Iris::WString> ()
	if dev.get_align_bits () > SECTOR_BITS:
		kdebug ("fat device doesn't support 512 byte access")
		return 1
	device_size = dev.get_size ()
	data = (char *)0x15000; //alloc_space (1)
	page = Iris::my_memory.create_page ()
	page.set_flags (Iris::Page::PAYING, Iris::Page::PAYING)
	Iris::my_memory.map (page, (unsigned)data)

	Fat fat

	fat.reset ()
	fat.print_br ()

	Iris::Cap root
	if fat.root_cluster:
		root = Iris::my_receiver.create_capability (Iris::Num (fat.root_cluster, 0))
	else:
		root = Iris::my_receiver.create_capability (Iris::Num (ROOT_CLUSTER, 0))

	Iris::my_parent.provide_capability <Iris::Directory> (root.copy ())
	Iris::free_cap (root)

	while true:
		Iris::wait ()
		unsigned dir = Iris::recv.protected_data.h
		if dir & 0x80000000:
			// File name.
			unsigned idx = Iris::recv.protected_data.l
			Iris::Cap reply = Iris::get_reply ()
			unsigned num = Iris::recv.data[1].l
			unsigned size = Iris::recv.data[0].h >> 16
			unsigned cmd = Iris::recv.data[0].l
			Fat::File f
			fat.get_dir_entry (dir & ~0x80000000, idx, &f)
			switch cmd:
				case Iris::String::GET_SIZE:
					kdebug ("filename size requested\n")
					reply.invoke (11)
					break
				case Iris::String::GET_CHARS:
					//kdebug ("filename chars requested\n")
					/**/union { unsigned u[4]; char c[16]; } u
					for unsigned k = 0; k < 4; ++k:
						u.u[k] = 0
					for unsigned k = 0; k + num < 11; ++k:
						u.c[k] = f.name[k + num]
					reply.invoke (Iris::Num (u.u[0], u.u[1]), Iris::Num (u.u[2], u.u[3]))
					break
				case Iris::String::GET_ALIGN_BITS:
					kdebug ("filename align requested\n")
					reply.invoke (0)
					break
				case Iris::String::GET_BLOCK:
				default:
					Iris::panic (Iris::recv.data[0].l, "invalid request for fat filename")
			Iris::free_cap (reply)
		else if dir:
			// File.
			unsigned idx = Iris::recv.protected_data.l
			Iris::Cap reply = Iris::get_reply ()
			Iris::Cap arg = Iris::get_arg ()
			Iris::Num num = Iris::recv.data[1]
			unsigned size = Iris::recv.data[0].h >> 16
			unsigned offset = Iris::recv.data[0].h & 0xffff
			unsigned cmd = Iris::recv.data[0].l
			Fat::File f
			fat.get_dir_entry (dir, idx, &f)
			switch cmd:
				case Iris::String::GET_SIZE:
					kdebug ("file size requested\n")
					reply.invoke (f.size)
					break
				case Iris::String::GET_CHARS:
					kdebug ("file chars requested\n")
					unsigned mask = 1 << (fat.cluster_size_bits) - 1
					f.load_cluster (num.l & ~mask)
					unsigned n = num.l & mask & ~0xf
					unsigned *dat = (unsigned *)(data + n)
					reply.invoke (Iris::Num (dat[0], dat[1]), Iris::Num (dat[2], dat[3]))
					break
				case Iris::String::GET_ALIGN_BITS:
					kdebug ("file align requested\n")
					reply.invoke (fat.cluster_size_bits)
					break
				case Iris::String::GET_BLOCK:
					kdebug ("file block requested\n")
					unsigned mask = 1 << (fat.cluster_size_bits) - 1
					if offset > PAGE_SIZE:
						kdebug ("invalid offset requested\n")
						break
					if size + offset > PAGE_SIZE:
						size = PAGE_SIZE - offset
					for unsigned i = 0; i < size; i += 1 << fat.cluster_size_bits:
						f.load_cluster ((num.l & ~mask) + i, arg, i + offset)
					reply.invoke ()
					break
				case Iris::WString::TRUNCATE:
				case Iris::WString::SET_CHARS:
				case Iris::WString::SET_BLOCK:
					Iris::panic (Iris::recv.data[0].l, "writing to files not supported yet")
				default:
					Iris::panic (Iris::recv.data[0].l, "invalid request for fat file")
			Iris::free_cap (reply)
			Iris::free_cap (arg)
		else:
			// Directory.
			if Iris::recv.protected_data.l != ROOT_CLUSTER:
				// Normal directory.
				switch Iris::recv.data[0].l:
					case Iris::Directory::GET_SIZE:
						kdebug ("dir size requested\n")
						Iris::recv.reply.invoke ()
						break
					case Iris::Directory::GET_NAME:
						kdebug ("dir name requested\n")
						Iris::recv.reply.invoke ()
						break
					case Iris::Directory::GET_FILE_RO:
						kdebug ("dir file requested\n")
						Iris::Cap reply = Iris::get_reply ()
						Iris::Cap ret = Iris::my_receiver.create_capability (Iris::Num (Iris::recv.data[1].l, Iris::recv.protected_data.l))
						reply.invoke (0, 0, ret.copy ())
						Iris::free_cap (reply)
						Iris::free_cap (ret)
						break
					case Iris::Directory::GET_FILE_INFO:
						kdebug ("dir file info requested\n")
						Iris::recv.reply.invoke ()
						break
					case Iris::Directory::LOCK_RO:
					case Iris::Directory::UNLOCK_RO:
						kdebug ("dir lock or unlock requested\n")
						Iris::recv.reply.invoke ()
						break
					default:
						kdebug ("invalid dir operation requested\n")
						Iris::recv.reply.invoke ()
						break
			else:
				// Non-fat32 root directory.
				switch Iris::recv.data[0].l:
					case Iris::Directory::GET_SIZE:
						kdebug ("root size requested\n")
						Iris::recv.reply.invoke (fat.root_entries)
						break
					case Iris::Directory::GET_NAME:
						//kdebug ("root name requested\n")
						Iris::Cap reply = Iris::get_reply ()
						Iris::Cap ret = Iris::my_receiver.create_capability (Iris::Num (Iris::recv.data[1].l, Iris::recv.protected_data.l | 0x80000000))
						reply.invoke (0, 0, ret.copy ())
						Iris::free_cap (reply)
						Iris::free_cap (ret)
						break
					case Iris::Directory::GET_FILE_RO:
						kdebug ("root file requested\n")
						Iris::Cap reply = Iris::get_reply ()
						Iris::Cap ret = Iris::my_receiver.create_capability (Iris::Num (Iris::recv.data[1].l, Iris::recv.protected_data.l))
						reply.invoke (0, 0, ret.copy ())
						Iris::free_cap (reply)
						Iris::free_cap (ret)
						break
					case Iris::Directory::GET_FILE_INFO:
						kdebug ("root file info requested\n")
						Iris::recv.reply.invoke ()
						break
					case Iris::Directory::LOCK_RO:
					case Iris::Directory::UNLOCK_RO:
						kdebug ("root lock or unlock requested\n")
						Iris::recv.reply.invoke ()
						break
					default:
						kdebug ("invalid root operation requested\n")
						Iris::recv.reply.invoke ()
						break