restore zmq.DRAFT_API meaning drafts are actually available

check both runtime zmq.has and build-time PYZMQ_DRAFT_API for pyzmq,
both of which have to be set for drafts to work.

If pyzmq is built without drafts and libzmq is, `has('draft')` will be true,
but draft api wrappers will not be available, leading to errors.

Author: minrk

tests/test_asyncio.py

@@ -406,7 +406,7 @@ async def test_poll_leak():
 
 
 async def test_draft_asyncio():
-    if not zmq.has("draft"):
+    if not zmq.DRAFT_API:
         pytest.skip("draft API")
     if zmq.zmq_version_info() < (4, 3, 2):
         pytest.skip("requires libzmq 4.3.2 for zmq_poller_fd")

zmq/__init__.py

@@ -80,7 +80,10 @@ def get_library_dirs():
 
 
 COPY_THRESHOLD = 65536
-DRAFT_API = backend.has("draft")
+# zmq.DRAFT_API represents _both_ the current runtime-loaded libzmq
+# and pyzmq were built with drafts,
+# which is required for pyzmq draft support
+DRAFT_API: bool = backend.has('draft') and backend.PYZMQ_DRAFT_API
 
 __all__ = (
     [

zmq/backend/__init__.pyi

@@ -100,6 +100,7 @@ class Context:
     def term(self) -> None: ...
 
 IPC_PATH_MAX_LEN: int
+PYZMQ_DRAFT_API: bool
 
 def has(capability: str) -> bool: ...
 def curve_keypair() -> tuple[bytes, bytes]: ...

zmq/backend/cffi/_cdefs.h

@@ -94,3 +94,5 @@ int zmq_wrap_msg_init_data(zmq_msg_t *msg,
                       void *data,
                       size_t size,
                       void *hint);
+
+#define PYZMQ_DRAFT_API ...

zmq/backend/cffi/socket.py

@@ -273,7 +273,7 @@ def get(self, option):
                 and self.get(SocketOption.THREAD_SAFE)
             ):
                 _check_version((4, 3, 2), "draft socket FD support via zmq_poller_fd")
-                if not zmq.has('draft'):
+                if not zmq.DRAFT_API:
                     raise RuntimeError("libzmq must be built with draft support")
                 warnings.warn(zmq.error.DraftFDWarning(), stacklevel=2)
 

zmq/backend/cffi/utils.py

@@ -75,4 +75,6 @@ def _retry_sys_call(f, *args, **kwargs):
     return rc
 
 
-__all__ = ['has', 'curve_keypair', 'curve_public']
+PYZMQ_DRAFT_API: bool = bool(C.PYZMQ_DRAFT_API)
+
+__all__ = ['has', 'curve_keypair', 'curve_public', 'PYZMQ_DRAFT_API']

zmq/backend/cython/_zmq.py

@@ -76,6 +76,7 @@
 from cython.cimports.libc.stdio import stderr as cstderr
 from cython.cimports.libc.stdlib import free, malloc
 from cython.cimports.libc.string import memcpy
+from cython.cimports.zmq.backend.cython import libzmq
 from cython.cimports.zmq.backend.cython._externs import (
     get_ipc_path_max_len,
     getpid,
@@ -163,6 +164,8 @@
 
 IPC_PATH_MAX_LEN: int = get_ipc_path_max_len()
 
+PYZMQ_DRAFT_API: bool = bool(libzmq.PYZMQ_DRAFT_API)
+
 
 @cfunc
 @inline
@@ -929,8 +932,10 @@ def get(self, option: C.int):
                     _check_version(
                         (4, 3, 2), "draft socket FD support via zmq_poller_fd"
                     )
-                    if not zmq.has('draft'):
-                        raise RuntimeError("libzmq must be built with draft support")
+                    if not zmq.DRAFT_API:
+                        raise RuntimeError(
+                            "libzmq and pyzmq must be built with draft support"
+                        )
                     warnings.warn(zmq.error.DraftFDWarning(), stacklevel=2)
 
                     # create a poller and retrieve its fd
@@ -1120,8 +1125,8 @@ def join(self, group: str | bytes):
         .. versionadded:: 17
         """
         _check_version((4, 2), "RADIO-DISH")
-        if not zmq.has('draft'):
-            raise RuntimeError("libzmq must be built with draft support")
+        if not zmq.DRAFT_API:
+            raise RuntimeError("libzmq and pyzmq must be built with draft support")
         if isinstance(group, str):
             group = group.encode('utf8')
         c_group: bytes = group
@@ -1139,8 +1144,8 @@ def leave(self, group):
         .. versionadded:: 17
         """
         _check_version((4, 2), "RADIO-DISH")
-        if not zmq.has('draft'):
-            raise RuntimeError("libzmq must be built with draft support")
+        if not zmq.DRAFT_API:
+            raise RuntimeError("libzmq and pyzmq must be built with draft support")
         rc: C.int = zmq_leave(self.handle, group)
         _check_rc(rc)
 
@@ -2027,6 +2032,7 @@ def monitored_queue(
 
 __all__ = [
     'IPC_PATH_MAX_LEN',
+    'PYZMQ_DRAFT_API',
     'Context',
     'Socket',
     'Frame',

zmq/backend/select.py

@@ -21,6 +21,7 @@
     'curve_public',
     'zmq_version_info',
     'IPC_PATH_MAX_LEN',
+    'PYZMQ_DRAFT_API',
 ]
 
 

zmq/utils/zmq_compat.h

@@ -57,13 +57,17 @@
 
 // libzmq 4.2 draft API
 #ifdef ZMQ_BUILD_DRAFT_API
+  #define PYZMQ_DRAFT_API 1
     #if ZMQ_VERSION >= 40200
         #define PYZMQ_DRAFT_42
     #endif
     #if ZMQ_VERSION >= 40302
         #define PYZMQ_DRAFT_432
     #endif
+#else
+  #define PYZMQ_DRAFT_API 0
 #endif
+
 #ifndef PYZMQ_DRAFT_42
     #define zmq_join(s, group) _missing
     #define zmq_leave(s, group) _missing