switch the PEM password callback to a C implementation (#3382)

* switch the PEM password callback to a C implementation

Calling from C to Python is fraught with edge cases, especially in
subinterpreter land. This commit moves the PEM password callback logic
into a small C function and then removes all the infrastructure for the
cffi callbacks (as we no longer have any)

* review feedback and update tests

* rename the struct

* aaand one more fix

1 files changed, 0 insertions, 19 deletions

diff --git a/src/cryptography/hazmat/bindings/openssl/binding.py b/src/cryptography/hazmat/bindings/openssl/binding.py
index b6617543..6f9359c7 100644
--- a/src/cryptography/hazmat/bindings/openssl/binding.py
+++ b/src/cryptography/hazmat/bindings/openssl/binding.py
@@ -61,25 +61,6 @@ def _openssl_assert(lib, ok):
         )
 
 
-def ffi_callback(signature, name, **kwargs):
-    """Callback dispatcher
-
-    The ffi_callback() dispatcher keeps callbacks compatible between dynamic
-    and static callbacks.
-    """
-    def wrapper(func):
-        if lib.Cryptography_STATIC_CALLBACKS:
-            # def_extern() returns a decorator that sets the internal
-            # function pointer and returns the original function unmodified.
-            ffi.def_extern(name=name, **kwargs)(func)
-            callback = getattr(lib, name)
-        else:
-            # callback() wraps the function in a cdata function.
-            callback = ffi.callback(signature, **kwargs)(func)
-        return callback
-    return wrapper
-
-
 def build_conditional_library(lib, conditional_names):
     conditional_lib = types.ModuleType("lib")
     excluded_names = set()