diff options
Diffstat (limited to 'tools/fsmaker/api.py')
| -rw-r--r-- | tools/fsmaker/api.py | 653 |
1 files changed, 653 insertions, 0 deletions
diff --git a/tools/fsmaker/api.py b/tools/fsmaker/api.py new file mode 100644 index 0000000..07e6440 --- /dev/null +++ b/tools/fsmaker/api.py @@ -0,0 +1,653 @@ +import os +import math +import struct + +S5_MAGIC = 0x727f +S5_CURRENT_VERSION = 3 +S5_BLOCK_SIZE = 4096 + +S5_NBLKS_PER_FNODE = 30 +S5_NDIRECT_BLOCKS = 28 +S5_MAX_FILE_BLOCKS = S5_NDIRECT_BLOCKS + math.floor(S5_BLOCK_SIZE / 4) +S5_MAX_FILE_SIZE = S5_MAX_FILE_BLOCKS * S5_BLOCK_SIZE + +S5_NAME_LEN = 28 +S5_DIRENT_SIZE = S5_NAME_LEN + 4 + +S5_INODE_SIZE = 16 + S5_NDIRECT_BLOCKS * 4 +S5_INODES_PER_BLOCK = S5_BLOCK_SIZE / S5_INODE_SIZE + +S5_TYPE_FREE = 0x0 +S5_TYPE_DATA = 0x1 +S5_TYPE_DIR = 0x2 +S5_TYPE_CHR = 0x4 +S5_TYPE_BLK = 0x8 +S5_TYPES = set([ S5_TYPE_FREE, S5_TYPE_DATA, S5_TYPE_DIR, S5_TYPE_CHR, S5_TYPE_BLK ]) + +class S5fsException(Exception): + + def __init__(self, msg): + self._msg = msg + + def __str__(self): + return self._msg + +class S5fsDiskSpaceException(S5fsException): + + def __init__(self): + S5fsException.__init__(self, "out of disk space") + +class Block: + + def __init__(self, simdisk, offset, blockno): + self._simdisk = simdisk + self._offset = offset + self._blockno = blockno + + def get_blockno(self): + return self._blockno + + def read(self, offset=0, size=None): + if (size == None): + size = S5_BLOCK_SIZE - offset + if (offset + size > S5_BLOCK_SIZE): + raise S5fsException("cannot read to {0}, exceeds block size of {1}".format(offset + size, S5_BLOCK_SIZE)) + self._simdisk._simfile.seek(int(self._offset + offset)) + res = self._simdisk._simfile.read(size) + return res + + def write(self, offset, data): + if (offset + len(data) > S5_BLOCK_SIZE): + raise S5fsException("cannot write to {0}, exceeds block size of {1}".format(offset + len(data), S5_BLOCK_SIZE)) + self._simdisk._simfile.seek(int(self._offset + offset)) + res = self._simdisk._simfile.write(data) + + def zero(self): + self._simdisk._simfile.seek(self._offset) + for i in xrange(S5_BLOCK_SIZE): + self._simdisk._simfile.write('\0') + + def free(self): + if (self._simdisk.get_nfree() < S5_NBLKS_PER_FNODE - 1): + self._simdisk.set_free_block(self._simdisk.get_nfree(), self._blockno) + self._simdisk.set_nfree(self._simdisk.get_nfree() + 1) + else: + for i in xrange(S5_NBLKS_PER_FNODE - 1): + self.write(i * 4, struct.pack("I", self._simdisk.get_free_block(i))) + self.write((S5_NBLKS_PER_FNODE - 1) * 4, struct.pack("I", self._simdisk.get_last_free_block())) + self._simdisk.set_last_free_block(self._blockno) + self._simdisk.set_nfree(0) + +class Dirent: + + def __init__(self, parent, inode, name, offset): + self._parent = parent + self.inode = inode + self.name = name + self._offset = offset + + def remove(self): + self._parent.write(self._offset + 4, '\0') + +class Inode: + + def __init__(self, simdisk, number, offset): + self._simdisk = simdisk + self._simfile = simdisk._simfile + self._number = number + self._offset = offset + + def get_next_free(self): + return self.get_size() + + def set_next_free(self, val): + return self.set_size(val) + + def get_size(self): + self._simfile.seek(int(self._offset)) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_size(self, val): + self._simfile.seek(int(self._offset)) + self._simfile.write(struct.pack("I", val)) + + def get_number(self): + self._simfile.seek(int(self._offset + 4)) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_number(self, val): + self._simfile.seek(int(self._offset + 4)) + self._simfile.write(struct.pack("I", val)) + + def get_type(self): + self._simfile.seek(int(self._offset + 8)) + return struct.unpack("H", self._simfile.read(2))[0] + + def set_type(self, val): + self._simfile.seek(int(self._offset + 8)) + self._simfile.write(struct.pack("H", val)) + + def get_link_count(self): + self._simfile.seek(int(self._offset + 10)) + return struct.unpack("h", self._simfile.read(2))[0] + + def set_link_count(self, val): + self._simfile.seek(int(self._offset + 10)) + self._simfile.write(struct.pack("h", val)) + + def get_direct_blockno(self, index): + if (index < S5_NDIRECT_BLOCKS): + self._simfile.seek(int(self._offset + 12 + index * 4)) + return struct.unpack("I", self._simfile.read(4))[0] + else: + raise S5fsException("direct block index {0} greater than max {1}".format(index, S5_NDIRECT_BLOCKS)) + + def set_direct_blockno(self, index, val): + if (index < S5_NDIRECT_BLOCKS): + self._simfile.seek(int(self._offset + 12 + index * 4)) + self._simfile.write(struct.pack("I", val)) + else: + raise S5fsException("direct block index {0} greater than max {1}".format(index, S5_NDIRECT_BLOCKS)) + + def get_indirect_blockno(self): + self._simfile.seek(int(self._offset + 12 + 4 * S5_NDIRECT_BLOCKS)) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_indirect_blockno(self, val): + self._simfile.seek(int(self._offset + 12 + 4 * S5_NDIRECT_BLOCKS)) + self._simfile.write(struct.pack("I", val)) + + def get_type_str(self, short=False): + t = self.get_type() + name = "INV" if short else "INVALID" + if (t == S5_TYPE_FREE): + name = "---" if short else "S5_TYPE_FREE" + elif (t == S5_TYPE_DATA): + name = "dat" if short else "S5_TYPE_DATA" + elif (t == S5_TYPE_DIR): + name = "dir" if short else "S5_TYPE_DIR" + elif (t == S5_TYPE_BLK): + name = "blk" if short else "S5_TYPE_BLK" + elif (t == S5_TYPE_CHR): + name = "chr" if short else "S5_TYPE_CHR" + return name if short else "{0} (0x{1:02x})".format(name, t) + + def get_summary(self): + res = "" + res += "num: {0}{1}\n".format(self.get_number(), "" if self.get_number() == self._number else " (INVALID, should be {0})".format(self.get_number())) + res += "type: {0}\n".format(self.get_type_str()) + if (self.get_type() != S5_TYPE_FREE): + res += "links: {0}\n".format(self.get_link_count()) + if (self.get_type() in set([ S5_TYPE_DATA, S5_TYPE_DIR ])): + res += "size: {0} bytes".format(self.get_size()) + if (self.get_size() > S5_MAX_FILE_SIZE): + res += " (INVALID, max file size is {0})".format(S5_MAX_FILE_SIZE) + elif (self.get_type() == S5_TYPE_DIR and self.get_size() % S5_DIRENT_SIZE != 0): + res += " (INVALID, directory size must be multiple of dirent size ({0}))".format(S5_DIRENT_SIZE) + elif (self.get_type() == S5_TYPE_DIR): + res += " ({0} dirents)".format(self.get_size() / S5_DIRENT_SIZE) + res += "\n" + res += "direct blocks ({0}):\n".format(S5_NDIRECT_BLOCKS) + for i in xrange(S5_NDIRECT_BLOCKS): + res += " {0:5}".format(self.get_direct_blockno(i)) + if ((i + 1) % 4 == 0): + res += "\n" + if (res[-1] != "\n"): + res += "\n" + res += "indirect block: {0}\n".format(self.get_indirect_blockno()) + elif (self.get_type() == S5_TYPE_FREE): + res += "next free: {0}\n".format(self.get_next_free()) + res = res[:-1] + return res + + def read(self, offset=0, size=None): + if (size == None): + size = self.get_size() + if (self.get_type() not in set([ S5_TYPE_DATA, S5_TYPE_DIR ])): + raise S5fsException("cannot read from inode of type " + self.get_type_str()) + size = min(size, min(S5_MAX_FILE_SIZE, self.get_size()) - offset) + res = "" + while (size > 0): + blockno = math.floor(offset / S5_BLOCK_SIZE) + blockoff = offset % S5_BLOCK_SIZE + ammount = min(S5_BLOCK_SIZE - blockoff, size) + if (blockno < S5_NDIRECT_BLOCKS): + blockno = self.get_direct_blockno(blockno) + else: + if (self.get_indirect_blockno() == 0): + blockno = 0 + else: + indirect = self._simdisk.get_block(self.get_indirect_blockno()) + blockno -= S5_NDIRECT_BLOCKS + blockno = struct.unpack("I", indirect.read(blockno * 4, 4))[0] + if (blockno == 0): + for i in xrange(ammount): + res += '\0' + else: + res += self._simdisk.get_block(blockno).read(blockoff, ammount) + offset += ammount + size -= ammount + return res + + def write(self, offset, data): + if (self.get_type() not in set([ S5_TYPE_DATA, S5_TYPE_DIR ])): + raise S5fsException("cannot write to inode of type " + self.get_type_str()) + if (offset + len(data) > S5_MAX_FILE_SIZE): + raise S5fsException("cannot write up to byte {0}, max file size is {1}".format(offset + len(data), S5_MAX_FILE_SIZE)) + remaining = len(data) + while (remaining > 0): + blockloc = math.floor(offset / S5_BLOCK_SIZE) + blockoff = offset % S5_BLOCK_SIZE + ammount = min(S5_BLOCK_SIZE - blockoff, remaining) + if (blockloc < S5_NDIRECT_BLOCKS): + blockno = self.get_direct_blockno(blockloc) + else: + if (self.get_indirect_blockno() == 0): + indirect = self._simdisk.alloc_block() + indirect.zero() + self.set_indirect_blockno(indirect.get_blockno()) + blockno = 0 + else: + indirect = self._simdisk.get_block(self.get_indirect_blockno()) + blockno = struct.unpack("I", indirect.read((blockloc - S5_NDIRECT_BLOCKS) * 4, 4))[0] + if (blockno == 0): + block = self._simdisk.alloc_block() + block.zero() + if (blockloc < S5_NDIRECT_BLOCKS): + self.set_direct_blockno(blockloc, block.get_blockno()) + else: + indirect = self._simdisk.get_block(self.get_indirect_blockno()) + indirect.write((blockloc - S5_NDIRECT_BLOCKS) * 4, struct.pack("I", block.get_blockno())) + else: + block = self._simdisk.get_block(blockno) + if (remaining == ammount): + block.write(blockoff, data[-remaining:]) + else: + block.write(blockoff, data[-remaining:-remaining+ammount]) + remaining -= ammount + offset += ammount + if (offset > self.get_size()): + self.set_size(offset) + + def truncate(self, size=0): + target = math.floor((size - 1) / S5_BLOCK_SIZE) + curr = math.floor(self.get_size() / S5_BLOCK_SIZE) + while (curr > target): + if (curr < S5_NDIRECT_BLOCKS): + blockno = self.get_direct_blockno(curr) + else: + if (self.get_indirect_blockno() == 0): + blockno = 0 + else: + indirect = self._simdisk.get_block(self.get_indirect_blockno()) + blockno = struct.unpack("I", indirect.read((curr - S5_NDIRECT_BLOCKS) * 4, 4))[0] + if (blockno > 0): + block = self._simdisk.get_block(blockno) + block.free() + if (curr < S5_NDIRECT_BLOCKS): + self.set_direct_blockno(curr, 0) + else: + indirect = self._simdisk.get_block(self.get_indirect_blockno()) + indirect.write((curr - S5_NDIRECT_BLOCKS) * 4, struct.pack("I", 0)) + if (curr == S5_NDIRECT_BLOCKS): + indirect.free() + self.set_indirect_blockno(0) + curr -= 1 + if (curr < target): + if (curr < S5_NDIRECT_BLOCKS): + self.set_indirect_blockno(0) + else: + if (self.get_indirect_blockno() != 0): + indirect = self._simdisk.get_block(self.get_indirect_blockno()) + indirect.write((curr - S5_NDIRECT_BLOCKS) * 4, struct.pack("I", 0)) + self.set_size(size) + + def _find_dirent(self, name, types=S5_TYPES): + if (self.get_type() != S5_TYPE_DIR): + raise S5fsException("cannot remove directory entry in non-directory inode of type " + self.get_type_str()) + if (self.get_size() % S5_DIRENT_SIZE != 0): + raise S5fsException("cannot remove directory entry, inode has size {0} not a multiple of dirent size {1}".format(self.get_size(), S5_DIRENT_SIZE)) + if (len(name) >= S5_NAME_LEN): + raise S5fsException("directroy entry name '{0}' too long, limit is {1} characters".format(name, S5_NAME_LEN - 1)) + for i in xrange(0, self.get_size(), S5_DIRENT_SIZE): + inode = struct.unpack("I", self.read(i, 4))[0] + parts = self.read(i + 4, S5_NAME_LEN).split('\0', 1) + if (len(parts) == 1): + raise S5fsException("directory entry name '{0}' does not contain a null character".format(name)) + if (name == parts[0]): + return Dirent(self, inode, name, i) + return None + + def unlink(self, name): + dirent = self._find_dirent(name) + if (dirent == None): + raise S5fsException("no such file or directory: {0}".format(name)) + inode = self._simdisk.get_inode(dirent.inode) + if (inode.get_type() == S5_TYPE_DIR): + raise S5fsException("cannot unlink directory: {0}".format(name)) + if (inode.get_link_count() < 1): + raise S5fsException("inode being unlinked has invalid link count of {1}: {0}".format(name, inode.get_link_count())) + dirent.remove() + if (inode.get_link_count() == 1): + inode.set_link_count(0) + inode.free() + else: + inode.set_link_count(inode.get_link_count() - 1) + + def rmdir(self, name): + if (name == "." or name == ".."): + raise S5fsException("cannot rmdir special directory: {0}".format(name)) + dirent = self._find_dirent(name) + if (dirent == None): + raise S5fsException("no such file or directory: {0}".format(name)) + inode = self._simdisk.get_inode(dirent.inode) + if (inode.get_type() != S5_TYPE_DIR): + raise S5fsException("cannot rmdir non-directory: {0}".format(name)) + if (not inode.is_empty()): + raise S5fsException("cannot rmdir non-empty directory: {0}".format(name)) + if (inode.get_link_count() != 2): + # the link count should be 2 because the parent still refers + # to the directory being removed and the directory refers to itself + print("link count" + str(inode.get_link_count())) + raise S5fsException("empty directory has link count of {1}: {0}".format(name, inode.get_link_count())) + dirent.remove() + self.set_link_count(self.get_link_count() - 1) + inode.set_link_count(0) + inode.free() + + def _make_dirent(self, inode, name): + if (self.get_type() != S5_TYPE_DIR): + raise S5fsException("cannot create directory entry in non-directory inode of type " + self.get_type_str()) + if (self.get_size() % S5_DIRENT_SIZE != 0): + raise S5fsException("cannot create directory entry, inode has size {0} not a multiple of dirent size {1}".format(self.get_size(), S5_DIRENT_SIZE)) + if (len(name) >= S5_NAME_LEN): + raise S5fsException("directroy entry name '{0}' too long, limit is {1} characters".format(name, S5_NAME_LEN - 1)) + empty = -1 + for i in xrange(0, self.get_size(), S5_DIRENT_SIZE): + direntname = self.read(i + 4, S5_NAME_LEN).split('\0', 1)[0] + if (direntname == name): + raise S5fsException("directory already has entry with same name: {0}".format(name)) + if (len(name) == 0): + empty = i + if (empty >= 0): + self.write(empty, struct.pack("I", inode)) + self.write(empty + 4, name.ljust(S5_NAME_LEN, '\0')) + else: + self.write(self.get_size(), struct.pack("I", inode)) + self.write(self.get_size(), name.ljust(S5_NAME_LEN, '\0')) + + def create(self, name): + inode = self._simdisk.alloc_inode() + try: + inode.set_type(S5_TYPE_DATA) + inode.set_size(0) + inode.set_link_count(1) + for i in xrange(S5_NDIRECT_BLOCKS): + inode.set_direct_blockno(i, 0) + inode.set_indirect_blockno(0) + self._make_dirent(inode.get_number(), name) + return inode + except S5fsException as e: + inode.free() + raise e + + def mkdir(self, name): + inode = self._simdisk.alloc_inode() + try: + inode.set_type(S5_TYPE_DIR) + inode.set_size(0) + inode.set_link_count(2) + for i in xrange(S5_NDIRECT_BLOCKS): + inode.set_direct_blockno(i, 0) + inode.set_indirect_blockno(0) + inode._make_dirent(inode.get_number(), ".") + inode._make_dirent(self.get_number(), "..") + self.set_link_count(self.get_link_count() + 1) + self._make_dirent(inode.get_number(), name) + return inode + except S5fsException as e: + inode.free() + raise e + + def getdents(self): + if (self.get_type() != S5_TYPE_DIR): + raise S5fsException("cannot get dirents from inode of type " + self.get_type_str()) + if (self.get_size() % S5_DIRENT_SIZE != 0): + raise S5fsException("cannot get dirents, inode has size {0} not a multiple of dirent size {1}".format(self.get_size(), S5_DIRENT_SIZE)) + for i in xrange(0, self.get_size(), S5_DIRENT_SIZE): + inode = struct.unpack("I", self.read(i, 4))[0] + name = self.read(i + 4, S5_NAME_LEN) + parts = name.split('\0', 1) + if (len(parts) == 1): + raise S5fsException("directory entry {0} in inode {1} does not contain a null character".format(i / S5_DIRENT_SIZE, self._number)) + name = parts[0] + if (len(name) > 0): + yield Dirent(self, inode, name, i) + + def is_empty(self): + for dirent in self.getdents(): + if (dirent.name != "." and dirent.name != ".."): + return False + return True + + def lookup(self, name): + if (len(name) >= S5_NAME_LEN): + raise S5fsException("directroy entry name '{0}' too long, limit is {1} characters".format(name, S5_NAME_LEN - 1)) + for dirent in self.getdents(): + if (dirent.name == name): + try: + return self._simdisk.get_inode(dirent.inode) + except S5fsException as e: + raise S5fsException("error looking up '{0}': {1}".format(name, str(e))) + return None + + def open(self, path, create=False): + opath = os.path.normpath(path) + path = opath.split("/") + curr = self + for seg in path[:-1]: + if (len(seg) == 0): + continue + curr = curr.lookup(seg) + if (curr == None): + if (not create): + return None + else: + raise S5fsException("segment '{0}' in path '{1}' does not exist".format(seg, opath)) + if (len(path[-1]) == 0): + return curr + last = curr.lookup(path[-1]) + if (None == last and create): + return curr.create(path[-1]) + return last + + def free(self): + if (self.get_size() != 0): + self.truncate() + self.set_type(S5_TYPE_FREE) + self.set_next_free(self._simdisk.get_free_inode()) + self._simdisk.set_free_inode(self._number) + +class Simdisk: + + def __init__(self, simfile): + self._simfile = simfile + + def get_magic(self): + self._simfile.seek(0) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_magic(self, val): + self._simfile.seek(0) + self._simfile.write(struct.pack("I", val)) + + def get_free_inode(self): + self._simfile.seek(4) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_free_inode(self, val): + self._simfile.seek(4) + self._simfile.write(struct.pack("I", val)) + + def get_nfree(self): + self._simfile.seek(8) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_nfree(self, val): + self._simfile.seek(8) + self._simfile.write(struct.pack("I", val)) + + def get_free_block(self, index): + if (index < S5_NBLKS_PER_FNODE - 1): + self._simfile.seek(12 + 4 * index) + return struct.unpack("I", self._simfile.read(4))[0] + else: + raise S5fsException("free block index {0} greater than max {1}".format(index, S5_NBLKS_PER_FNODE - 2)) + + def set_free_block(self, index, val): + if (index < S5_NBLKS_PER_FNODE - 1): + self._simfile.seek(12 + 4 * index) + self._simfile.write(struct.pack("I", val)) + else: + raise S5fsException("free block index {0} greater than max {1}".format(index, S5_NBLKS_PER_FNODE - 2)) + + def get_last_free_block(self): + self._simfile.seek(12 + 4 * (S5_NBLKS_PER_FNODE - 1)) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_last_free_block(self, val): + self._simfile.seek(12 + 4 * (S5_NBLKS_PER_FNODE - 1)) + self._simfile.write(struct.pack("I", val)) + + def get_root_inode(self): + self._simfile.seek(12 + 4 * S5_NBLKS_PER_FNODE) + return struct.unpack("I", self._simfile.read(4))[0] + + def get_num_inodes(self): + self._simfile.seek(16 + 4 * S5_NBLKS_PER_FNODE) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_num_inodes(self, val): + self._simfile.seek(16 + 4 * S5_NBLKS_PER_FNODE) + self._simfile.write(struct.pack("I", val)) + + def get_version(self): + self._simfile.seek(20 + 4 * S5_NBLKS_PER_FNODE) + return struct.unpack("I", self._simfile.read(4))[0] + + def set_version(self, val): + self._simfile.seek(20 + 4 * S5_NBLKS_PER_FNODE) + self._simfile.write(struct.pack("I", val)) + + def get_super_block_summary(self): + res = "" + res += "magic: 0x{0:04x} ({1})\n".format(self.get_magic(), "VALID" if self.get_magic() == S5_MAGIC else "INVALID") + res += "version: 0x{0:04x}{1}\n".format(self.get_version(), "" if self.get_version() == S5_CURRENT_VERSION else " (INVALID)") + res += "num inodes: {0}\n".format(self.get_num_inodes()) + res += "free inode: {0}{1}\n".format(self.get_free_inode(), "" if self.get_free_inode() < self.get_num_inodes() else " (INVALID)") + res += "root inode: {0}{1}\n".format(self.get_root_inode(), "" if self.get_root_inode() < self.get_num_inodes() else " (INVALID)") + res += "free blocks ({0}{1}):\n".format(self.get_nfree(), "" if self.get_nfree() <= S5_NBLKS_PER_FNODE else (", too large shouldn't exceed " + str(S5_NBLKS_PER_FNODE))) + for i in xrange(min(self.get_nfree(), S5_NBLKS_PER_FNODE - 1)): + res += " {0}".format(self.get_free_block(i)) + if ((i + 1) % 10 == 0): + res += "\n" + if (res[-1] != "\n"): + res += "\n" + res += " last free block: {0}\n".format(self.get_last_free_block()) + return res + + def format(self, inodes, size): + if (inodes < 1): + raise S5fsException("cannot format disk with {0} inodes, must have at least one".format(inodes)) + if (size % S5_BLOCK_SIZE != 0): + raise S5fsException("cannot format disk to size {0} which is not a multiple of the block size {1}".format(size, S5_BLOCK_SIZE)) + blocks = int(size / S5_BLOCK_SIZE) + iblocks = int(math.floor((inodes - 1) / S5_INODES_PER_BLOCK) + 1) + if (iblocks + 1 >= blocks): + raise S5fsException("cannot format disk of size {0} with {1} inodes, the inodes require at least {2} bytes of space".format(size, inodes, (1 + iblocks) * S5_BLOCK_SIZE)) + self._simfile.truncate() + self._simfile.seek(size) + self._simfile.write("") + + self.set_magic(S5_MAGIC) + self.set_version(S5_CURRENT_VERSION) + self.set_num_inodes(inodes) + for i in xrange(inodes): + inode = self.get_inode(i) + inode.set_number(i) + inode.set_type(S5_TYPE_FREE) + inode.set_next_free(i + 1) + inode.set_next_free(0xffffffff) + self.set_free_inode(0) + + self.set_last_free_block(0xffffffff) + i = 0 + for num in xrange(iblocks+1, blocks): + if (i == S5_NBLKS_PER_FNODE - 1): + block = self.get_block(num) + for j in xrange(S5_NBLKS_PER_FNODE - 1): + block.write(j * 4, struct.pack("I", self.get_free_block(j))) + block.write((S5_NBLKS_PER_FNODE - 1) * 4, struct.pack("I", self.get_last_free_block())) + self.set_last_free_block(num) + i = 0 + else: + self.set_free_block(i, num) + i += 1 + self.set_nfree(i) + + root = self.alloc_inode() + for i in xrange(S5_NDIRECT_BLOCKS): + root.set_direct_blockno(i, 0) + root.set_indirect_blockno(0) + root.set_type(S5_TYPE_DIR) + root.set_size(0) + root.set_link_count(2) + root._make_dirent(root.get_number(), ".") + root._make_dirent(root.get_number(), "..") + + def free_inodes(self): + inext = self.get_free_inode() + while (inext != 0xffffffff): + try: + curr = self.get_inode(inext) + yield inext + inext = curr.get_free_inode() + except S5fsException as e: + raise S5fsException("error encountered while iterating free inodes: {0}".format(str(e))) + + def get_inode(self, index): + offset = S5_BLOCK_SIZE * (1 + math.floor(index / S5_INODES_PER_BLOCK)) + S5_INODE_SIZE * (index % S5_INODES_PER_BLOCK) + if (index >= self.get_num_inodes()): + raise S5fsException("cannot get inode {0}, there are only {1} inodes on disk".format(index, self.get_num_inodes())) + return Inode(self, index, offset) + + def alloc_inode(self): + if (self.get_free_inode() == 0xffffffff): + raise S5fsException("disk is out of inodes") + inode = self.get_inode(self.get_free_inode()) + self.set_free_inode(inode.get_next_free()) + return inode + + def get_block(self, index): + offset = S5_BLOCK_SIZE * index + return Block(self, offset, index) + + def alloc_block(self): + if (self.get_nfree() > S5_NBLKS_PER_FNODE - 1): + raise S5fsException("nfree {0} is invalid, maximum value is {1}".format(self.get_nfree(), S5_NBLKS_PER_FNODE - 1)) + if (self.get_nfree() == 0): + if (self.get_last_free_block() == 0xffffffff): + raise S5fsDiskSpaceException() + else: + block = self.get_block(self.get_last_free_block()) + for i in xrange(S5_NBLKS_PER_FNODE - 1): + self.set_free_block(i, struct.unpack("I", block.read(i * 4, 4))[0]) + self.set_last_free_block(struct.unpack("I", block.read((S5_NBLKS_PER_FNODE - 1) * 4, 4))[0]) + self.set_nfree(S5_NBLKS_PER_FNODE - 1) + return block + else: + self.set_nfree(self.get_nfree() - 1) + return self.get_block(self.get_free_block(self.get_nfree())) + + def open(self, path, create=False): + return self.get_inode(self.get_root_inode()).open(path, create=create) |