Update leb128.py

Author: mohanson

pywasm/leb128.py

@@ -6,18 +6,19 @@ class _U:
     def encode(i: int) -> bytearray:
         # Encode the int i using unsigned leb128 and return the encoded bytearray.
         assert i >= 0
-        r = []
+        r = bytearray()
         while True:
-            byte = i & 0x7f
+            b = i & 0x7f
             i = i >> 7
             if i == 0:
-                r.append(byte)
-                return bytearray(r)
-            r.append(0x80 | byte)
+                r.append(b)
+                return r
+            r.append(0x80 | b)
 
     @staticmethod
     def decode(b: bytearray) -> int:
         # Decode the unsigned leb128 encoded bytearray.
+        assert len(b) > 0
         r = 0
         for i, e in enumerate(b):
             r = r + ((e & 0x7f) << (i * 7))
@@ -29,7 +30,10 @@ def decode_reader(r: typing.BinaryIO) -> typing.Tuple[int, int]:
         # of bytes read.
         a = bytearray()
         while True:
-            b = ord(r.read(1))
+            b = r.read(1)
+            if len(b) != 1:
+                raise EOFError
+            b = ord(b)
             a.append(b)
             if (b & 0x80) == 0:
                 break
@@ -40,21 +44,24 @@ class _I:
     @staticmethod
     def encode(i: int) -> bytearray:
         # Encode the int i using signed leb128 and return the encoded bytearray.
-        r = []
+        r = bytearray()
         while True:
-            byte = i & 0x7f
+            b = i & 0x7f
             i = i >> 7
-            if (i == 0 and byte & 0x40 == 0) or (i == -1 and byte & 0x40 != 0):
-                r.append(byte)
-                return bytearray(r)
-            r.append(0x80 | byte)
+            if (i == 0 and b & 0x40 == 0) or (i == -1 and b & 0x40 != 0):
+                r.append(b)
+                return r
+            r.append(0x80 | b)
 
     @staticmethod
     def decode(b: bytearray) -> int:
         # Decode the signed leb128 encoded bytearray.
+        assert len(b) > 0
         r = 0
         for i, e in enumerate(b):
             r = r + ((e & 0x7f) << (i * 7))
+        i = len(b) - 1
+        e = b[i]
         if e & 0x40 != 0:
             r |= - (1 << (i * 7) + 7)
         return r
@@ -65,7 +72,10 @@ def decode_reader(r: typing.BinaryIO) -> typing.Tuple[int, int]:
         # of bytes read.
         a = bytearray()
         while True:
-            b = ord(r.read(1))
+            b = r.read(1)
+            if len(b) != 1:
+                raise EOFError
+            b = ord(b)
             a.append(b)
             if (b & 0x80) == 0:
                 break