From 84988aa2f6cf45c36486f40ee5307e9bc7d00998 Mon Sep 17 00:00:00 2001
From: Aaron Griffith <aargri@gmail.com>
Date: Fri, 25 Mar 2011 19:48:55 -0400
Subject: [PATCH] 0-byte region files no longer crash the whole program

---
 nbt.py | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/nbt.py b/nbt.py
index 73730a0..075335c 100644
--- a/nbt.py
+++ b/nbt.py
@@ -217,12 +217,16 @@ class MCRFileReader(object):
             # go to the correct entry in the chunk location table
             self._file.seek(4 * (x + y * 32))
         
-        # 3-byte offset in 4KiB sectors
-        offset_sectors = self._read_24bit_int()
-        
-        # 1-byte length in 4KiB sectors, rounded up
-        byte = self._file.read(1)
-        length_sectors = struct.unpack("B", byte)[0]
+        try:
+            # 3-byte offset in 4KiB sectors
+            offset_sectors = self._read_24bit_int()
+            
+            # 1-byte length in 4KiB sectors, rounded up
+            byte = self._file.read(1)
+            length_sectors = struct.unpack("B", byte)[0]
+        except (IndexError, struct.error):
+            # got a problem somewhere
+            return None
         
         # check for empty chunks
         if offset_sectors == 0 or length_sectors == 0:
@@ -247,8 +251,11 @@ class MCRFileReader(object):
             # go to the correct entry in the chunk timestamp table
             self._file.seek(4 * (x + y * 32) + 4096)
         
-        bytes = self._file.read(4)
-        timestamp = struct.unpack(">I", bytes)[0]
+        try:
+            bytes = self._file.read(4)
+            timestamp = struct.unpack(">I", bytes)[0]
+        except (IndexError, struct.error):
+            return 0
         
         return timestamp