Fix socketcan timestamp on newer 32 bit kernel (#341)

Kernel now defines old and new SO_TIMESTAMP and can send both of them in
ancillary data.

---------

Co-authored-by: Pavel Kirienko <[email protected]>

.github/workflows/test-and-release.yml

@@ -10,7 +10,8 @@ jobs:
   pycyphal-test:
     name: Test PyCyphal
     # Run on push OR on 3rd-party PR.
-    if: (github.event_name == 'push') || (github.event.pull_request.author_association == 'NONE')
+    # https://docs.github.com/en/webhooks/webhook-events-and-payloads?actionType=edited#pull_request
+    if: (github.event_name == 'push') || github.event.pull_request.head.repo.fork
     strategy:
       fail-fast: false
       matrix:

CHANGELOG.rst

@@ -7,6 +7,9 @@ v1.19
 -----
 - Implement configure_acceptance_filters for socketcan.
 
+- **v1.19.1:**
+  Fix socketcan timestamp on newer 32 bit kernel.
+
 v1.18
 -----
 - Add FileClient2 which reports errors by raising exceptions.

pycyphal/_version.py

@@ -1 +1 @@
-__version__ = "1.19.0"
+__version__ = "1.19.1"

pycyphal/transport/can/media/socketcan/_socketcan.py

@@ -87,7 +87,8 @@ def __init__(self, iface_name: str, mtu: int, loop: typing.Optional[asyncio.Abst
         self._maybe_thread: typing.Optional[threading.Thread] = None
         self._loopback_enabled = False
 
-        self._ancillary_data_buffer_size = socket.CMSG_SPACE(_TIMEVAL_STRUCT.size)  # type: ignore
+        # We could receive both old and new timestamps, so we need to allocate space for both.
+        self._ancillary_data_buffer_size = socket.CMSG_SPACE(_TIMEVAL_STRUCT_OLD.size) + socket.CMSG_SPACE(_TIMEVAL_STRUCT_NEW.size)  # type: ignore
 
         super().__init__()
 
@@ -232,9 +233,15 @@ def _read_frame(self, ts_mono_ns: int) -> typing.Tuple[Timestamp, Envelope]:
             loopback = bool(msg_flags & socket.MSG_CONFIRM)  # type: ignore
             ts_system_ns = 0
             for cmsg_level, cmsg_type, cmsg_data in ancdata:
-                if cmsg_level == socket.SOL_SOCKET and cmsg_type == _SO_TIMESTAMP:
-                    sec, usec = _TIMEVAL_STRUCT.unpack(cmsg_data)
+                if cmsg_level == socket.SOL_SOCKET and cmsg_type == _SO_TIMESTAMP_OLD:
+                    # This structure provides time in platform native size
+                    sec, usec = _TIMEVAL_STRUCT_OLD.unpack(cmsg_data)
                     ts_system_ns = (sec * 1_000_000 + usec) * 1000
+                elif cmsg_level == socket.SOL_SOCKET and cmsg_type == _SO_TIMESTAMP_NEW:
+                    # This structure is present only when there is a 64 bit time on a 32 bit platform
+                    sec, usec = _TIMEVAL_STRUCT_NEW.unpack(cmsg_data)
+                    ts_system_ns = (sec * 1_000_000 + usec) * 1000
+                    break  # The new timestamp is preferred
                 else:
                     assert False, f"Unexpected ancillary data: {cmsg_level}, {cmsg_type}, {cmsg_data!r}"
 
@@ -309,10 +316,14 @@ class _NativeFrameDataCapacity(enum.IntEnum):
 #     __u8    data[CANFD_MAX_DLEN] __attribute__((aligned(8)));
 # };
 _FRAME_HEADER_STRUCT = struct.Struct("=IBB2x")  # Using standard size because the native definition relies on stdint.h
-_TIMEVAL_STRUCT = struct.Struct("@Ll")  # Using native size because the native definition uses plain integers
 
-# From the Linux kernel; not exposed via the Python's socket module
-_SO_TIMESTAMP = 29
+# structs __kernel_old_timeval and __kernel_sock_timeval in include/uapi/linux/time_types.h
+_TIMEVAL_STRUCT_OLD = struct.Struct("@ll")  # Using native size because the native definition uses plain integers
+_TIMEVAL_STRUCT_NEW = struct.Struct("@qq")  # New structure uses s64 for seconds and microseconds
+
+# From the Linux kernel (include/uapi/asm-generic/socket.h); not exposed via the Python's socket module
+_SO_TIMESTAMP_OLD = 29
+_SO_TIMESTAMP_NEW = 63
 _SO_SNDBUF = 7
 
 _CANFD_BRS = 1
@@ -342,7 +353,7 @@ def _make_socket(iface_name: str, can_fd: bool, native_frame_size: int) -> socke
     s = socket.socket(socket.PF_CAN, socket.SOCK_RAW, socket.CAN_RAW)  # type: ignore
     try:
         s.bind((iface_name,))
-        s.setsockopt(socket.SOL_SOCKET, _SO_TIMESTAMP, 1)  # timestamping
+        s.setsockopt(socket.SOL_SOCKET, _SO_TIMESTAMP_OLD, 1)  # timestamping
         default_sndbuf_size = s.getsockopt(socket.SOL_SOCKET, _SO_SNDBUF)
         blocking_sndbuf_size = (native_frame_size + _SKB_OVERHEAD) * _get_tx_queue_len(iface_name)