Fix silent NameError when CFFI bindings are missing, adds _FFIPlaceholder that raises ImportError with instructions

Author: cconlon

wolfssl/__init__.py

@@ -38,8 +38,10 @@
 try:
     from wolfssl._ffi import ffi as _ffi
     from wolfssl._ffi import lib as _lib
-except ImportError:
-    pass
+except ImportError as e:
+    from wolfssl.utils import _FFIPlaceholder
+    _ffi = _FFIPlaceholder(e)
+    _lib = _FFIPlaceholder(e)
 
 from wolfssl.utils import t2b
 
@@ -169,7 +171,7 @@ def __init__(self, protocol, server_side=None):
         self.verify_mode = CERT_NONE
 
     def __del__(self):
-        if getattr(self, 'native_object', _ffi.NULL) != _ffi.NULL:
+        if getattr(self, 'native_object', None) is not None and self.native_object != _ffi.NULL:
             _lib.wolfSSL_CTX_free(self.native_object)
 
     @property
@@ -474,7 +476,7 @@ def __del__(self):
         self._release_native_object()
 
     def _release_native_object(self):
-        if getattr(self, 'native_object', _ffi.NULL) != _ffi.NULL:
+        if getattr(self, 'native_object', None) is not None and self.native_object != _ffi.NULL:
             _lib.wolfSSL_free(self.native_object)
             self.native_object = _ffi.NULL
 

wolfssl/_methods.py

@@ -25,8 +25,10 @@
 try:
     from wolfssl._ffi import lib as _lib
     from wolfssl._ffi import ffi as _ffi
-except ImportError:
-    pass
+except ImportError as e:
+    from wolfssl.utils import _FFIPlaceholder
+    _ffi = _FFIPlaceholder(e)
+    _lib = _FFIPlaceholder(e)
 
 
 PROTOCOL_SSLv23 = 1
@@ -111,5 +113,5 @@ def __init__(self, protocol, server_side):
             raise MemoryError("Cannot allocate method object")
 
     def __del__(self):
-        if getattr(self, 'native_object', _ffi.NULL) != _ffi.NULL:
+        if getattr(self, 'native_object', None) is not None and self.native_object != _ffi.NULL:
             _native_free(self.native_object, _DYNAMIC_TYPE_METHOD)

wolfssl/utils.py

@@ -30,6 +30,19 @@
 _BINARY_TYPE = bytes if _PY3 else str
 
 
+class _FFIPlaceholder:
+    def __init__(self, cause=None):
+        object.__setattr__(self, '_cause', cause)
+
+    def __getattr__(self, name):
+        raise ImportError(
+            "wolfssl._ffi is not available. The CFFI bindings have not been "
+            "compiled. If you installed wolfssl via pip, the build may have "
+            "failed silently. Try reinstalling with: "
+            "pip install --no-binary wolfssl wolfssl"
+        ) from self._cause
+
+
 def t2b(string):
     """
     Converts text to binary.