From 6f3cb059fd1f3a57ffd70c9d54a394a85a6ea13d Mon Sep 17 00:00:00 2001 From: Antoine Pitrou Date: Fri, 30 Jun 2017 10:54:24 +0200 Subject: [PATCH] [3.6] bpo-30807: signal.setitimer() may disable the timer by mistake (GH-2493) (#2497) * bpo-30807: signal.setitimer() may disable the timer by mistake * Add NEWS blurb (cherry picked from commit 729780a810bbcb12b245a1b652302a601fc9f6fd) --- Lib/test/test_signal.py | 9 +++++++++ .../Library/2017-06-29-22-04-44.bpo-30807.sLtjY-.rst | 6 ++++++ Modules/signalmodule.c | 4 ++++ 3 files changed, 19 insertions(+) create mode 100644 Misc/NEWS.d/next/Library/2017-06-29-22-04-44.bpo-30807.sLtjY-.rst diff --git a/Lib/test/test_signal.py b/Lib/test/test_signal.py index ab42ed70cc..aa2b8bb48c 100644 --- a/Lib/test/test_signal.py +++ b/Lib/test/test_signal.py @@ -611,6 +611,15 @@ class ItimerTest(unittest.TestCase): # and the handler should have been called self.assertEqual(self.hndl_called, True) + def test_setitimer_tiny(self): + # bpo-30807: C setitimer() takes a microsecond-resolution interval. + # Check that float -> timeval conversion doesn't round + # the interval down to zero, which would disable the timer. + self.itimer = signal.ITIMER_REAL + signal.setitimer(self.itimer, 1e-6) + time.sleep(1) + self.assertEqual(self.hndl_called, True) + class PendingSignalsTests(unittest.TestCase): """ diff --git a/Misc/NEWS.d/next/Library/2017-06-29-22-04-44.bpo-30807.sLtjY-.rst b/Misc/NEWS.d/next/Library/2017-06-29-22-04-44.bpo-30807.sLtjY-.rst new file mode 100644 index 0000000000..ce6f48a61f --- /dev/null +++ b/Misc/NEWS.d/next/Library/2017-06-29-22-04-44.bpo-30807.sLtjY-.rst @@ -0,0 +1,6 @@ +signal.setitimer() may disable the timer when passed a tiny value. + +Tiny values (such as 1e-6) are valid non-zero values for setitimer(), which +is specified as taking microsecond-resolution intervals. However, on some +platform, our conversion routine could convert 1e-6 into a zero interval, +therefore disabling the timer instead of (re-)scheduling it. diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c index ed2f4e8cf0..55e4c2a00e 100644 --- a/Modules/signalmodule.c +++ b/Modules/signalmodule.c @@ -139,6 +139,10 @@ timeval_from_double(double d, struct timeval *tv) { tv->tv_sec = floor(d); tv->tv_usec = fmod(d, 1.0) * 1000000.0; + /* Don't disable the timer if the computation above rounds down to zero. */ + if (d > 0.0 && tv->tv_sec == 0 && tv->tv_usec == 0) { + tv->tv_usec = 1; + } } Py_LOCAL_INLINE(double) -- 2.40.0