[3.7] bpo-40515: Require OPENSSL_THREADS (GH-19953) (GH-20120)

Author: tiran

Misc/NEWS.d/next/Library/2020-05-06-13-51-19.bpo-40515.TUCvYB.rst

@@ -0,0 +1,3 @@
+The :mod:`ssl` and :mod:`hashlib` modules now actively check that OpenSSL is
+build with thread support. Python 3.7.0 made thread support mandatory and no
+longer works safely with a no-thread builds.

Modules/_hashopenssl.c

@@ -32,6 +32,10 @@ module _hashlib
 [clinic start generated code]*/
 /*[clinic end generated code: output=da39a3ee5e6b4b0d input=c2b4ff081bac4be1]*/
 
+#ifndef OPENSSL_THREADS
+#  error "OPENSSL_THREADS is not defined, Python requires thread-safe OpenSSL"
+#endif
+
 #define MUNCH_SIZE INT_MAX
 
 #ifndef HASH_OBJ_CONSTRUCTOR

Modules/_ssl.c

@@ -75,6 +75,10 @@ static PySocketModule_APIObject PySocketModule;
 #  endif
 #endif
 
+#ifndef OPENSSL_THREADS
+#  error "OPENSSL_THREADS is not defined, Python requires thread-safe OpenSSL"
+#endif
+
 /* SSL error object */
 static PyObject *PySSLErrorObject;
 static PyObject *PySSLCertVerificationErrorObject;
@@ -5875,7 +5879,7 @@ PyInit__ssl(void)
     if (!_setup_ssl_threads()) {
         return NULL;
     }
-#elif OPENSSL_VERSION_1_1 && defined(OPENSSL_THREADS)
+#elif OPENSSL_VERSION_1_1
     /* OpenSSL 1.1.0 builtin thread support is enabled */
     _ssl_locks_count++;
 #endif