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gh-126876: Fix socket internal_select() for large timeout #126968

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Merged
merged 2 commits into from
Nov 19, 2024
Merged

gh-126876: Fix socket internal_select() for large timeout #126968

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gh-126876: Fix socket internal_select() for large timeout
vstinner Nov 18, 2024
7b2a15d
Skip test on Windows
vstinner Nov 18, 2024
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27 changes: 27 additions & 0 deletions Lib/test/test_socket.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5132,6 +5132,33 @@ def _testRecv(self):
# send data: recv() will no longer block
self.cli.sendall(MSG)

def testLargeTimeout(self):
# gh-126876: Check that a timeout larger than INT_MAX is replaced with
# INT_MAX in the poll() code path. The following assertion must not
# fail: assert(INT_MIN <= ms && ms <= INT_MAX).
large_timeout = _testcapi.INT_MAX + 1

# test recv() with large timeout
conn, addr = self.serv.accept()
self.addCleanup(conn.close)
try:
conn.settimeout(large_timeout)
except OverflowError:
# On Windows, settimeout() fails with OverflowError, whereas
# we want to test recv(). Just give up silently.
return
msg = conn.recv(len(MSG))

def _testLargeTimeout(self):
# test sendall() with large timeout
large_timeout = _testcapi.INT_MAX + 1
self.cli.connect((HOST, self.port))
try:
self.cli.settimeout(large_timeout)
except OverflowError:
return
self.cli.sendall(MSG)


class FileObjectClassTestCase(SocketConnectedTest):
"""Unit tests for the object returned by socket.makefile()
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5 changes: 4 additions & 1 deletion Modules/socketmodule.c
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Expand Up @@ -810,7 +810,9 @@ internal_select(PySocketSockObject *s, int writing, PyTime_t interval,

/* s->sock_timeout is in seconds, timeout in ms */
ms = _PyTime_AsMilliseconds(interval, _PyTime_ROUND_CEILING);
assert(ms <= INT_MAX);
if (ms > INT_MAX) {
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Yes, indeed my proposal was wrong. Because later ms is casted to int: n = poll(&pollfd, 1, (int)ms);

Thanks for picking this up!

ms = INT_MAX;
}

/* On some OSes, typically BSD-based ones, the timeout parameter of the
poll() syscall, when negative, must be exactly INFTIM, where defined,
Expand All @@ -822,6 +824,7 @@ internal_select(PySocketSockObject *s, int writing, PyTime_t interval,
ms = -1;
#endif
}
assert(INT_MIN <= ms && ms <= INT_MAX);

Py_BEGIN_ALLOW_THREADS;
n = poll(&pollfd, 1, (int)ms);
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