move Sync class into coro.log.asn1

This way log processors don't have to duplicate it.

coro/log/asn1.py

@@ -3,9 +3,12 @@ from coro.asn1.python import encode
 import coro
 import struct
 
+# four bytes from os.urandom().
+MAGIC = '%\xf1\xbfB'
+
 class Logger:
 
-    magic = '%\xf1\xbfB'
+    magic = MAGIC
 
     def __init__ (self, file):
         self.encode = encode
@@ -21,3 +24,36 @@ class Logger:
             )
         )
         self.file.flush()
+
+
+class Sync:
+
+    magic = MAGIC
+
+    def __init__ (self):
+        self.state = 0
+        self.last = None
+    def feed (self, ch):
+        if ch == self.magic[self.state]:
+            self.state += 1
+            if self.state == 4:
+                return True
+            else:
+                return False
+        else:
+            self.state = 0
+            self.last = ch
+            return False
+    def resync (self, fdin):
+        self.state = 0
+        give_up = 10000
+        i = 0
+        while i < give_up:
+            ch = fdin.read (1)
+            i += 1
+            if ch == '':
+                raise EOFError
+            else:
+                if self.feed (ch):
+                    return
+        raise ValueError ("unable to sync: is this an asn1 log file?")

coro/log/catlog

@@ -6,37 +6,7 @@ import struct
 import sys
 import datetime
 from coro.asn1.python import decode
-
-class Sync:
-
-    magic = '%\xf1\xbfB'
-    def __init__ (self):
-        self.state = 0
-        self.last = None
-    def feed (self, ch):
-        if ch == self.magic[self.state]:
-            self.state += 1
-            if self.state == 4:
-                return True
-            else:
-                return False
-        else:
-            self.state = 0
-            self.last = ch
-            return False
-    def resync (self, fdin):
-        self.state = 0
-        give_up = 10000
-        i = 0
-        while i < give_up:
-            ch = fdin.read (1)
-            i += 1
-            if ch == '':
-                raise EOFError
-            else:
-                if self.feed (ch):
-                    return
-        raise ValueError ("unable to sync: is this an asn1 log file?")
+from coro.log.asn1 import Sync
 
 def is_binary (ob):
     if type(ob) is not bytes: