bpo-37085: Expose SocketCAN bcm_msg_head flags (#13646)

Expose the CAN_BCM SocketCAN constants used in the bcm_msg_head struct
flags (provided by <linux/can/bcm.h>) under the socket library.

This adds the following constants with a CAN_BCM prefix:

  * SETTIMER
  * STARTTIMER
  * TX_COUNTEVT
  * TX_ANNOUNCE
  * TX_CP_CAN_ID
  * RX_FILTER_ID
  * RX_CHECK_DLC
  * RX_NO_AUTOTIMER
  * RX_ANNOUNCE_RESUME
  * TX_RESET_MULTI_IDX
  * RX_RTR_FRAME
  * CAN_FD_FRAME

The CAN_FD_FRAME flag was introduced in the 4.8 kernel, while the other
ones were present since SocketCAN drivers were mainlined in 2.6.25. As
such, it is probably unnecessary to guard against these constants being
missing.

5 files changed, 38 insertions, 0 deletions

diff --git a/Doc/library/socket.rst b/Doc/library/socket.rst
index e3ddebdcbc..eebbe810ab 100644
--- a/Doc/library/socket.rst
+++ b/Doc/library/socket.rst
@@ -391,6 +391,9 @@ Constants
 
    .. availability:: Linux >= 2.6.25.
 
+   .. note::
+      The :data:`CAN_BCM_CAN_FD_FRAME` flag is only available on Linux >= 4.8.
+
    .. versionadded:: 3.4
 
 .. data:: CAN_RAW_FD_FRAMES
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 2705eff479..11b2a38ad7 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -1908,6 +1908,19 @@ class BasicCANTest(unittest.TestCase):
         socket.CAN_BCM_RX_TIMEOUT   # cyclic message is absent
         socket.CAN_BCM_RX_CHANGED   # updated CAN frame (detected content change)
 
+        # flags
+        socket.CAN_BCM_SETTIMER
+        socket.CAN_BCM_STARTTIMER
+        socket.CAN_BCM_TX_COUNTEVT
+        socket.CAN_BCM_TX_ANNOUNCE
+        socket.CAN_BCM_TX_CP_CAN_ID
+        socket.CAN_BCM_RX_FILTER_ID
+        socket.CAN_BCM_RX_CHECK_DLC
+        socket.CAN_BCM_RX_NO_AUTOTIMER
+        socket.CAN_BCM_RX_ANNOUNCE_RESUME
+        socket.CAN_BCM_TX_RESET_MULTI_IDX
+        socket.CAN_BCM_RX_RTR_FRAME
+
     def testCreateSocket(self):
         with socket.socket(socket.PF_CAN, socket.SOCK_RAW, socket.CAN_RAW) as s:
             pass
diff --git a/Misc/ACKS b/Misc/ACKS
index e02e8e1fa5..9ff74ec0cc 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -397,6 +397,7 @@ Alon Diamant
 Toby Dickenson
 Mark Dickinson
 Jack Diederich
+Karl Ding
 Daniel Diniz
 Humberto Diogenes
 Yves Dionne
diff --git a/Misc/NEWS.d/next/Library/2019-06-18-16-29-31.bpo-37085.GeYaD6.rst b/Misc/NEWS.d/next/Library/2019-06-18-16-29-31.bpo-37085.GeYaD6.rst
new file mode 100644
index 0000000000..e8db521d7a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-06-18-16-29-31.bpo-37085.GeYaD6.rst
@@ -0,0 +1,2 @@
+Add the optional Linux SocketCAN Broadcast Manager constants, used as flags
+to configure the BCM behaviour, in the socket module.  Patch by Karl Ding.
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index 73e64f235a..99e350b433 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -7656,6 +7656,8 @@ PyInit__socket(void)
 #endif
 #ifdef HAVE_LINUX_CAN_BCM_H
     PyModule_AddIntMacro(m, CAN_BCM);
+
+    /* BCM opcodes */
     PyModule_AddIntConstant(m, "CAN_BCM_TX_SETUP", TX_SETUP);
     PyModule_AddIntConstant(m, "CAN_BCM_TX_DELETE", TX_DELETE);
     PyModule_AddIntConstant(m, "CAN_BCM_TX_READ", TX_READ);
@@ -7668,6 +7670,23 @@ PyInit__socket(void)
     PyModule_AddIntConstant(m, "CAN_BCM_RX_STATUS", RX_STATUS);
     PyModule_AddIntConstant(m, "CAN_BCM_RX_TIMEOUT", RX_TIMEOUT);
     PyModule_AddIntConstant(m, "CAN_BCM_RX_CHANGED", RX_CHANGED);
+
+    /* BCM flags */
+    PyModule_AddIntConstant(m, "CAN_BCM_SETTIMER", SETTIMER);
+    PyModule_AddIntConstant(m, "CAN_BCM_STARTTIMER", STARTTIMER);
+    PyModule_AddIntConstant(m, "CAN_BCM_TX_COUNTEVT", TX_COUNTEVT);
+    PyModule_AddIntConstant(m, "CAN_BCM_TX_ANNOUNCE", TX_ANNOUNCE);
+    PyModule_AddIntConstant(m, "CAN_BCM_TX_CP_CAN_ID", TX_CP_CAN_ID);
+    PyModule_AddIntConstant(m, "CAN_BCM_RX_FILTER_ID", RX_FILTER_ID);
+    PyModule_AddIntConstant(m, "CAN_BCM_RX_CHECK_DLC", RX_CHECK_DLC);
+    PyModule_AddIntConstant(m, "CAN_BCM_RX_NO_AUTOTIMER", RX_NO_AUTOTIMER);
+    PyModule_AddIntConstant(m, "CAN_BCM_RX_ANNOUNCE_RESUME", RX_ANNOUNCE_RESUME);
+    PyModule_AddIntConstant(m, "CAN_BCM_TX_RESET_MULTI_IDX", TX_RESET_MULTI_IDX);
+    PyModule_AddIntConstant(m, "CAN_BCM_RX_RTR_FRAME", RX_RTR_FRAME);
+#ifdef CAN_FD_FRAME
+    /* CAN_FD_FRAME was only introduced in the 4.8.x kernel series */
+    PyModule_AddIntConstant(m, "CAN_BCM_CAN_FD_FRAME", CAN_FD_FRAME);
+#endif
 #endif
 #ifdef SOL_RDS
     PyModule_AddIntMacro(m, SOL_RDS);