Author: Armin Rigo <[email protected]>
Branch:
Changeset: r2876:b7deca8bf7f4
Date: 2017-01-28 17:15 +0100
http://bitbucket.org/cffi/cffi/changeset/b7deca8bf7f4/
Log: Expand the warning box
diff --git a/doc/source/using.rst b/doc/source/using.rst
--- a/doc/source/using.rst
+++ b/doc/source/using.rst
@@ -776,13 +776,21 @@
Callbacks are provided for the ABI mode or for backward
compatibility. If you are using the out-of-line API mode, it is
recommended to use the `extern "Python"`_ mechanism instead of
- callbacks: it gives faster and cleaner code. It also avoids a
- SELinux issue whereby the setting of ``deny_execmem`` must be left
- to ``off`` in order to use callbacks. (A fix in cffi was
- attempted---see the ``ffi_closure_alloc`` branch---but was not
- merged because it creates potential memory corruption with
- ``fork()``. For more information, `see here.`__)
+ callbacks: it gives faster and cleaner code. It also avoids several
+ issues with old-style callbacks:
+ - On less common architecture, libffi is more likely to crash on
+ callbacks (`e.g. on NetBSD`__);
+
+ - On hardened systems like PAX and SELinux, the extra memory
+ protections can interfere (for example, on SELinux you need to
+ run with ``deny_execmem`` set to ``off``).
+
+ Note also that a cffi fix for the latter issue was attempted---see
+ the ``ffi_closure_alloc`` branch---but was not merged because it
+ creates potential `memory corruption`__ with ``fork()``.
+
+.. __: https://github.com/pyca/pyopenssl/issues/596
.. __: https://bugzilla.redhat.com/show_bug.cgi?id=1249685
Warning: like ffi.new(), ffi.callback() returns a cdata that has
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