def save_chunk(self, chunk):
"""
Saves the given chunk, which should be a ``TagRoot``, to the region
file.
"""
# Compress chunk
chunk_x = chunk.body.value["Level"].value["xPos"].value
chunk_z = chunk.body.value["Level"].value["zPos"].value
chunk = zlib.compress(chunk.to_bytes())
chunk = Buffer.pack('IB', len(chunk), 2) + chunk
chunk_length = 1 + (len(chunk) - 1) // 4096
# Load extents
extents = [(0, 2)]
self.fd.seek(0)
buff = Buffer(self.fd.read(4096))
for idx in range(1024):
z, x = divmod(idx, 32)
entry = buff.unpack('I')
offset, length = entry >> 8, entry & 0xFF
if offset > 0 and not (x == chunk_x and z == chunk_z):
extents.append((offset, length))
extents.sort()
extents.append((extents[-1][0] + extents[-1][1] + chunk_length, 0))
# Compute new extent
for idx in range(len(extents) - 1):
start = extents[idx][0] + extents[idx][1]
end = extents[idx + 1][0]
if (end - start) >= chunk_length:
chunk_offset = start
extents.insert(idx + 1, (chunk_offset, chunk_length))
break
# Write extent header
self.fd.seek(4 * (32 * chunk_z + chunk_x))
self.fd.write(
Buffer.pack('I', (chunk_offset << 8) | (chunk_length & 0xFF)))
# Write timestamp header
self.fd.seek(4096 + 4 * (32 * chunk_z + chunk_x))
self.fd.write(Buffer.pack('I', int(time.time())))
# Write chunk
self.fd.seek(4096 * chunk_offset)
self.fd.write(chunk)
# Truncate file
self.fd.seek(4096 * extents[-1][0])
self.fd.truncate()
def load_chunk(self, chunk_x, chunk_z):
"""
Loads the chunk at the given co-ordinates from the region file.
The co-ordinates should range from 0 to 31. Returns a ``TagRoot``.
"""
buff = Buffer()
# Read extent header
self.fd.seek(4 * (32 * chunk_z + chunk_x))
buff.add(self.fd.read(4))
entry = buff.unpack('I')
chunk_offset, chunk_length = entry >> 8, entry & 0xFF
if chunk_offset == 0:
raise ValueError((chunk_x, chunk_z))
# Read chunk
self.fd.seek(4096 * chunk_offset)
buff.add(self.fd.read(4096 * chunk_length))
chunk = buff.read(buff.unpack('IB')[0])
chunk = zlib.decompress(chunk)
chunk = TagRoot.from_bytes(chunk)
return chunk
def test_unpack():
buffer = Buffer()
for fmt, data, values in pack_unpack_vectors:
buffer.add(data)
assert buffer.unpack(fmt) == values