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5 changes: 3 additions & 2 deletions Lib/socket.py
Original file line number Diff line number Diff line change
Expand Up @@ -563,7 +563,8 @@ def send_fds(sock, buffers, fds, flags=0, address=None):
import array

return sock.sendmsg(buffers, [(_socket.SOL_SOCKET,
_socket.SCM_RIGHTS, array.array("i", fds))])
_socket.SCM_RIGHTS, array.array("i", fds))],
flags, address)
__all__.append("send_fds")

if hasattr(_socket.socket, "recvmsg"):
Expand All @@ -579,7 +580,7 @@ def recv_fds(sock, bufsize, maxfds, flags=0):
# Array of ints
fds = array.array("i")
msg, ancdata, flags, addr = sock.recvmsg(bufsize,
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Let's rename the result flags as msg_flags to be consistent with the signature (don't forget to update return ...)

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Done.

_socket.CMSG_LEN(maxfds * fds.itemsize))
_socket.CMSG_LEN(maxfds * fds.itemsize), flags)
for cmsg_level, cmsg_type, cmsg_data in ancdata:
if (cmsg_level == _socket.SOL_SOCKET and cmsg_type == _socket.SCM_RIGHTS):
fds.frombytes(cmsg_data[:
Expand Down
105 changes: 91 additions & 14 deletions Lib/test/test_socket.py
Original file line number Diff line number Diff line change
Expand Up @@ -7037,19 +7037,22 @@ def test_dual_stack_client_v6(self):
@requireAttrs(socket, "recv_fds")
@requireAttrs(socket, "AF_UNIX")
class SendRecvFdsTests(unittest.TestCase):
def testSendAndRecvFds(self):
def close_pipes(pipes):
for fd1, fd2 in pipes:
os.close(fd1)
os.close(fd2)

def _cleanup_fds(self, fds):
def close_fds(fds):
for fd in fds:
os.close(fd)
self.addCleanup(close_fds, fds)

def _test_pipe(self, rfd, wfd, msg):
assert len(msg) < 512
os.write(wfd, msg)
data = os.read(rfd, 512)
self.assertEqual(data, msg)
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Suggested change
assert len(msg) < 512
os.write(wfd, msg)
data = os.read(rfd, 512)
self.assertEqual(data, msg)
os.write(wfd, msg)
data = os.read(rfd, len(msg))
self.assertEqual(data, msg)

I think we can do it like this right?

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man 7 pipe says:

POSIX.1 says that writes of less than PIPE_BUF bytes must be atomic: the output data is written to the pipe as a contiguous sequence. [...] POSIX.1 requires PIPE_BUF to be at least 512 bytes.

I hardcoded 512 here, which may look confusing. I've updated it to make it more clear.


def testSendAndRecvFds(self):
# send 10 file descriptors
pipes = [os.pipe() for _ in range(10)]
self.addCleanup(close_pipes, pipes)
self._cleanup_fds(fd for pair in pipes for fd in pair)
fds = [rfd for rfd, wfd in pipes]

# use a UNIX socket pair to exchange file descriptors locally
Expand All @@ -7058,21 +7061,95 @@ def close_fds(fds):
socket.send_fds(sock1, [MSG], fds)
# request more data and file descriptors than expected
msg, fds2, flags, addr = socket.recv_fds(sock2, len(MSG) * 2, len(fds) * 2)
self.addCleanup(close_fds, fds2)
self._cleanup_fds(fds2)

self.assertEqual(msg, MSG)
self.assertEqual(len(fds2), len(fds))
self.assertEqual(flags, 0)
# don't test addr

# test that file descriptors are connected
for index, fds in enumerate(pipes):
rfd, wfd = fds
os.write(wfd, str(index).encode())
for index, ((_, wfd), rfd) in enumerate(zip(pipes, fds2)):
self._test_pipe(rfd, wfd, str(index).encode())

@unittest.skipUnless(sys.platform in ("linux", "android", "darwin"),
"works on Linux and macOS")
def test_send_recv_fds_with_addrs(self):
sock1 = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
sock2 = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
rfd, wfd = os.pipe()
self.addCleanup(os.close, rfd)
self.addCleanup(os.close, wfd)

with tempfile.TemporaryDirectory() as tmpdir, sock1, sock2:
sock1_addr = os.path.join(tmpdir, "sock1")
sock2_addr = os.path.join(tmpdir, "sock2")
sock1.bind(sock1_addr)
sock2.bind(sock2_addr)
sock2.setblocking(False)

socket.send_fds(sock1, [MSG], [rfd], address=sock2_addr)
msg, fds, flags, addr = socket.recv_fds(sock2, len(MSG), 1)
self._cleanup_fds(fds)

self.assertEqual(msg, MSG)
self.assertEqual(len(fds), 1)
self.assertEqual(addr, sock1_addr)

self._test_pipe(fds[0], wfd, MSG)

for index, rfd in enumerate(fds2):
data = os.read(rfd, 100)
self.assertEqual(data, str(index).encode())
@requireAttrs(socket, "MSG_PEEK")
@unittest.skipUnless(sys.platform in ("linux", "android"), "works on Linux")
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I'm back here, but does it work on freebsd?

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Unfortunately no. On FreeBSD recvmsg with MSG_PEEK returns random bytes in the ancillary data, which looks like some kind of uninitialized memory.

def test_recv_fds_peek(self):
rfd, wfd = os.pipe()
self.addCleanup(os.close, rfd)
self.addCleanup(os.close, wfd)

sock1, sock2 = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM)
with sock1, sock2:
socket.send_fds(sock1, [MSG], [rfd])
sock2.setblocking(False)

# peek message on sock2
peek_len = len(MSG) // 2
msg, fds, flags, addr = socket.recv_fds(sock2, peek_len, 1,
socket.MSG_PEEK)
self._cleanup_fds(fds)

self.assertEqual(len(msg), peek_len)
self.assertEqual(msg, MSG[:peek_len])
self.assertEqual(flags & socket.MSG_TRUNC, socket.MSG_TRUNC)
self.assertEqual(len(fds), 1)
self._test_pipe(fds[0], wfd, MSG)

# will raise BlockingIOError if MSG_PEEK didn't work
msg, fds, flags, addr = socket.recv_fds(sock2, len(MSG), 1)
self._cleanup_fds(fds)

self.assertEqual(msg, MSG)
self.assertEqual(len(fds), 1)
self._test_pipe(fds[0], wfd, MSG)

@requireAttrs(socket, "MSG_DONTWAIT")
@unittest.skipUnless(sys.platform in ("linux", "android"), "Linux specific test")
def test_send_fds_dontwait(self):
rfd, wfd = os.pipe()
self.addCleanup(os.close, rfd)
self.addCleanup(os.close, wfd)

sock1, sock2 = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM)
with sock1, sock2:
sock1.setblocking(True)
with self.assertRaises(BlockingIOError):
for _ in range(64 * 1024):
socket.send_fds(sock1, [MSG], [rfd], socket.MSG_DONTWAIT)

msg, fds, flags, addr = socket.recv_fds(sock2, len(MSG), 1)
self._cleanup_fds(fds)

self.assertEqual(msg, MSG)
self.assertEqual(len(fds), 1)
self._test_pipe(fds[0], wfd, MSG)


class FreeThreadingTests(unittest.TestCase):
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix ``flags`` and ``address`` parameters which were ignored in
``socket.send_fds`` and ``socket.recv_fds``.
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