tests: git: test larger blob encode/decode

[bup.git] / lib / bup / vint.py

diff --git a/lib/bup/vint.py b/lib/bup/vint.py
index 31e2dfa24731d50bb0edd288d148b473d6de8b88..086cb302087d8edae343631c04c68a87440c35f8 100644 (file)
--- a/lib/bup/vint.py
+++ b/lib/bup/vint.py
@@ -5,43 +5,114 @@
 # This code is covered under the terms of the GNU Library General
 # Public License as described in the bup LICENSE file.
 
-from cStringIO import StringIO
+# Variable length integers are encoded as vints -- see lucene.
+
+from __future__ import absolute_import
+from io import BytesIO
+import sys
+
+from bup import compat
 
-# Variable length integers are encoded as vints -- see jakarta lucene.
 
 def write_vuint(port, x):
+    write = port.write
+    bytes_from_uint = compat.bytes_from_uint
     if x < 0:
         raise Exception("vuints must not be negative")
     elif x == 0:
-        port.write('\0')
+        write(bytes_from_uint(0))
     else:
-        while x:
+        while True:
             seven_bits = x & 0x7f
             x >>= 7
             if x:
-                port.write(chr(0x80 | seven_bits))
+                write(bytes_from_uint(0x80 | seven_bits))
             else:
-                port.write(chr(seven_bits))
+                write(bytes_from_uint(seven_bits))
+                break
 
 
 def read_vuint(port):
     c = port.read(1)
-    if c == '':
-        raise EOFError('encountered EOF while reading vuint');
+    if not c:
+        raise EOFError('encountered EOF while reading vuint')
+    assert isinstance(c, bytes)
+    if ord(c) == 0:
+        return 0
     result = 0
     offset = 0
-    while c:
+    while True:
         b = ord(c)
         if b & 0x80:
             result |= ((b & 0x7f) << offset)
             offset += 7
             c = port.read(1)
+            if not c:
+                raise EOFError('encountered EOF while reading vuint')
         else:
             result |= (b << offset)
             break
     return result
 
 
+def write_vint(port, x):
+    # Sign is handled with the second bit of the first byte.  All else
+    # matches vuint.
+    write = port.write
+    bytes_from_uint = compat.bytes_from_uint
+    if x == 0:
+        write(bytes_from_uint(0))
+    else:
+        if x < 0:
+            x = -x
+            sign_and_six_bits = (x & 0x3f) | 0x40
+        else:
+            sign_and_six_bits = x & 0x3f
+        x >>= 6
+        if x:
+            write(bytes_from_uint(0x80 | sign_and_six_bits))
+            write_vuint(port, x)
+        else:
+            write(bytes_from_uint(sign_and_six_bits))
+
+
+def read_vint(port):
+    c = port.read(1)
+    if not c:
+        raise EOFError('encountered EOF while reading vint')
+    assert isinstance(c, bytes)
+    negative = False
+    result = 0
+    offset = 0
+    # Handle first byte with sign bit specially.
+    b = ord(c)
+    if b & 0x40:
+        negative = True
+    result |= (b & 0x3f)
+    if b & 0x80:
+        offset += 6
+        c = port.read(1)
+    elif negative:
+        return -result
+    else:
+        return result
+    while True:
+        b = ord(c)
+        if b & 0x80:
+            result |= ((b & 0x7f) << offset)
+            offset += 7
+            c = port.read(1)
+            if not c:
+                raise EOFError('encountered EOF while reading vint')
+        else:
+            result |= (b << offset)
+            break
+    if negative:
+        return -result
+    else:
+        return result
+
+
 def write_bvec(port, x):
     write_vuint(port, len(x))
     port.write(x)
@@ -55,29 +126,37 @@ def read_bvec(port):
 def skip_bvec(port):
     port.read(read_vuint(port))
 
-
-def pack(types, *args):
+def send(port, types, *args):
     if len(types) != len(args):
         raise Exception('number of arguments does not match format string')
-    port = StringIO()
     for (type, value) in zip(types, args):
         if type == 'V':
             write_vuint(port, value)
+        elif type == 'v':
+            write_vint(port, value)
         elif type == 's':
             write_bvec(port, value)
         else:
             raise Exception('unknown xpack format string item "' + type + '"')
-    return port.getvalue()
-
 
-def unpack(types, data):
+def recv(port, types):
     result = []
-    port = StringIO(data)
     for type in types:
         if type == 'V':
             result.append(read_vuint(port))
+        elif type == 'v':
+            result.append(read_vint(port))
         elif type == 's':
             result.append(read_bvec(port))
         else:
             raise Exception('unknown xunpack format string item "' + type + '"')
     return result
+
+def pack(types, *args):
+    port = BytesIO()
+    send(port, types, *args)
+    return port.getvalue()
+
+def unpack(types, data):
+    port = BytesIO(data)
+    return recv(port, types)