Created
November 2, 2016 22:10
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Removes a single node from a whole Minetest world (SQLite3 backend only)
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#!/usr/bin/env python3 | |
import sys | |
import os.path | |
import struct | |
import zlib | |
import sqlite3 | |
class BufferConsumer(): | |
def __init__(self, buf): | |
assert(type(buf) == bytes) | |
self.buf = buf | |
self.off = 0 | |
def remaining(self): | |
return len(self.buf) - self.off | |
def tell(self): | |
return self.off | |
def skip(self, length): | |
if length > self.remaining(): | |
raise EOFError() | |
self.off += length | |
def read(self, length): | |
if length > self.remaining(): | |
raise EOFError() | |
ret = self.buf[self.off:self.off+length] | |
self.off += length | |
return ret | |
def read_a(self, length): | |
return self.read(length).decode("ascii", "ignore") | |
def read_s(self, fmt): | |
fmt = "!" + fmt | |
return struct.unpack(fmt, self.read(struct.calcsize(fmt))) | |
def read_z(self): | |
d = zlib.decompressobj() | |
clen = self.remaining() | |
ret = d.decompress(self.buf[self.off:]) | |
ret += d.flush() | |
# special impl. so tell() works correctly | |
clen = clen - len(d.unused_data) | |
self.off += clen | |
return ret | |
def process_block(data, to_replace): | |
copybefore, newidmap, copyafter = 0, b"", 0 | |
trig = False | |
### | |
buf = BufferConsumer(data) | |
ver, _, _, _ = buf.read_s("BBBB") | |
assert(ver >= 22) | |
_ = buf.read_z() # node data | |
_ = buf.read_z() # metadata | |
if ver == 23: | |
buf.skip(1) | |
elif ver == 24: | |
ver2, length = buf.read_s("BH") | |
assert(ver2 == 1) | |
buf.skip(length*10) | |
ver2, count = buf.read_s("BH") | |
assert(ver2 == 0) | |
for i in range(count): | |
_ = buf.read_s("Biii") | |
length = buf.read_s("H")[0] | |
buf.skip(length) | |
_ = buf.read_s("I")[0] | |
copybefore = buf.tell() # | |
ver2, count = buf.read_s("BH") | |
assert(ver2 == 0) | |
newidmap += struct.pack("!BH", ver2, count) # | |
for i in range(count): | |
nid, nlen = buf.read_s("HH") | |
name = buf.read_a(nlen) | |
if name == to_replace: # | |
name = "air" # | |
trig = True # | |
newidmap += struct.pack("!HH", nid, len(name)) # | |
newidmap += name.encode("ascii") # | |
copyafter = buf.tell() # | |
if ver >= 25: | |
length, count = buf.read_s("BH") | |
assert(length == 10) | |
for i in range(count): | |
_ = buf.read_s("HII") | |
assert(buf.remaining() == 0) | |
### | |
return (1 if trig else 0), data[:copybefore] + newidmap + data[copyafter:] | |
if len(sys.argv) < 3: | |
print("Usage: blacknode.py <map dir> <node name>") | |
exit(1) | |
if not os.path.isfile(sys.argv[1] + "/map.sqlite"): | |
print("Map database doesn't exist?!") | |
exit(1) | |
conn = sqlite3.connect(sys.argv[1] + "/map.sqlite") | |
nodename = sys.argv[2] | |
c_total, c_rem = 0, 0 | |
for row in conn.execute("SELECT pos FROM blocks"): | |
blockdata = next(conn.execute("SELECT data FROM blocks WHERE pos = ?", row))[0] | |
try: | |
ret, blockdata = process_block(blockdata, nodename) | |
except AssertionError: | |
print("Skipping a MapBlock because we can't decode it..") | |
continue | |
conn.execute("UPDATE blocks SET data = ? WHERE pos = ?", (blockdata, row[0])) | |
c_total += 1 | |
c_rem += ret | |
conn.commit() | |
print("Removed node from %d of total %d MapBlocks" % (c_rem, c_total)) | |
conn.close() |
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