From 9a956ed5a42301ee1efb5642cc0f381751d917f5 Mon Sep 17 00:00:00 2001
From: Rob Austein <sra@hactrn.net>
Date: Wed, 21 Mar 2018 09:08:30 +0000
Subject: Supply our own context manager instead of using contextlib.

contextlib is cute, but incompatible with other coroutine schemes like
Tornado, so just write our own context manager for xdrlib.Unpacker.
---
 cryptech/libhal.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/cryptech/libhal.py b/cryptech/libhal.py
index acd1abb..273a8a0 100644
--- a/cryptech/libhal.py
+++ b/cryptech/libhal.py
@@ -43,7 +43,6 @@ import uuid
 import xdrlib
 import socket
 import logging
-import contextlib
 
 logger = logging.getLogger(__name__)
 
@@ -408,6 +407,15 @@ class PKey(Handle):
     def import_pkey(self, pkcs8, kek, flags = 0):
         return self.hsm.pkey_import(kekek = self, pkcs8 = pkcs8, kek = kek, flags = flags)
 
+class ContextManagedUnpacker(xdrlib.Unpacker):
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.done()
+
+
 class HSM(object):
 
     mixed_mode = False
@@ -429,7 +437,7 @@ class HSM(object):
             logger.debug("send: %s", ":".join("{:02x}".format(ord(c)) for c in msg))
         self.socket.sendall(msg)
 
-    def _recv(self, code):      # Returns an xdrlib.Unpacker
+    def _recv(self, code):      # Returns a ContextManagedUnpacker
         closed = False
         while True:
             msg = [self.sockfile.read(1)]
@@ -442,7 +450,7 @@ class HSM(object):
             msg = slip_decode("".join(msg))
             if not msg:
                 continue
-            msg = xdrlib.Unpacker("".join(msg))
+            msg = ContextManagedUnpacker("".join(msg))
             if msg.unpack_uint() != code:
                 continue
             return msg
@@ -480,7 +488,6 @@ class HSM(object):
             self._pack_arg(packer, name)
             self._pack_arg(packer, HAL_PKEY_ATTRIBUTE_NIL if value is None else value)
 
-    @contextlib.contextmanager
     def rpc(self, code, *args, **kwargs):
         client = kwargs.get("client", 0)
         packer = xdrlib.Packer()
@@ -491,8 +498,7 @@ class HSM(object):
         unpacker = self._recv(code)
         client = unpacker.unpack_uint()
         self._raise_if_error(unpacker.unpack_uint())
-        yield unpacker
-        unpacker.done()
+        return unpacker
 
     def get_version(self):
         with self.rpc(RPC_FUNC_GET_VERSION) as r:
-- 
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