[Python-checkins] bpo-35189: Retry fnctl calls on EINTR (GH-10413)
Victor Stinner
webhook-mailer at python.org
Fri Nov 23 10:46:15 EST 2018
https://github.com/python/cpython/commit/b409ffa848b280c1db1b4f450bfae14f263099ac
commit: b409ffa848b280c1db1b4f450bfae14f263099ac
branch: master
author: nierob <nierob at users.noreply.github.com>
committer: Victor Stinner <vstinner at redhat.com>
date: 2018-11-23T16:46:12+01:00
summary:
bpo-35189: Retry fnctl calls on EINTR (GH-10413)
Modify the following fnctl function to retry if interrupted by a signal
(EINTR): flock, lockf, fnctl.
files:
A Misc/NEWS.d/next/Library/2018-11-09-13-35-36.bpo-35189.gog-sl.rst
M Lib/test/eintrdata/eintr_tester.py
M Modules/fcntlmodule.c
diff --git a/Lib/test/eintrdata/eintr_tester.py b/Lib/test/eintrdata/eintr_tester.py
index 18d9d8451feb..c2eaf0128a5f 100644
--- a/Lib/test/eintrdata/eintr_tester.py
+++ b/Lib/test/eintrdata/eintr_tester.py
@@ -10,6 +10,7 @@
import contextlib
import faulthandler
+import fcntl
import os
import select
import signal
@@ -486,5 +487,43 @@ def test_devpoll(self):
self.assertGreaterEqual(dt, self.sleep_time)
+class FNTLEINTRTest(EINTRBaseTest):
+ def _lock(self, lock_func, lock_name):
+ self.addCleanup(support.unlink, support.TESTFN)
+ code = '\n'.join((
+ "import fcntl, time",
+ "with open('%s', 'wb') as f:" % support.TESTFN,
+ " fcntl.%s(f, fcntl.LOCK_EX)" % lock_name,
+ " time.sleep(%s)" % self.sleep_time))
+ start_time = time.monotonic()
+ proc = self.subprocess(code)
+ with kill_on_error(proc):
+ with open(support.TESTFN, 'wb') as f:
+ while True: # synchronize the subprocess
+ dt = time.monotonic() - start_time
+ if dt > 60.0:
+ raise Exception("failed to sync child in %.1f sec" % dt)
+ try:
+ lock_func(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
+ lock_func(f, fcntl.LOCK_UN)
+ time.sleep(0.01)
+ except BlockingIOError:
+ break
+ # the child locked the file just a moment ago for 'sleep_time' seconds
+ # that means that the lock below will block for 'sleep_time' minus some
+ # potential context switch delay
+ lock_func(f, fcntl.LOCK_EX)
+ dt = time.monotonic() - start_time
+ self.assertGreaterEqual(dt, self.sleep_time)
+ self.stop_alarm()
+ proc.wait()
+
+ def test_lockf(self):
+ self._lock(fcntl.lockf, "lockf")
+
+ def test_flock(self):
+ self._lock(fcntl.flock, "flock")
+
+
if __name__ == "__main__":
unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2018-11-09-13-35-36.bpo-35189.gog-sl.rst b/Misc/NEWS.d/next/Library/2018-11-09-13-35-36.bpo-35189.gog-sl.rst
new file mode 100644
index 000000000000..3408ca4eec44
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-11-09-13-35-36.bpo-35189.gog-sl.rst
@@ -0,0 +1,2 @@
+Modify the following fnctl function to retry if interrupted by a signal
+(EINTR): flock, lockf, fnctl
diff --git a/Modules/fcntlmodule.c b/Modules/fcntlmodule.c
index 77ddebf3ee0d..a938d9e88bf0 100644
--- a/Modules/fcntlmodule.c
+++ b/Modules/fcntlmodule.c
@@ -64,6 +64,7 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
char *str;
Py_ssize_t len;
char buf[1024];
+ int async_err = 0;
if (arg != NULL) {
int parse_result;
@@ -75,12 +76,13 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
return NULL;
}
memcpy(buf, str, len);
- Py_BEGIN_ALLOW_THREADS
- ret = fcntl(fd, code, buf);
- Py_END_ALLOW_THREADS
+ do {
+ Py_BEGIN_ALLOW_THREADS
+ ret = fcntl(fd, code, buf);
+ Py_END_ALLOW_THREADS
+ } while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
if (ret < 0) {
- PyErr_SetFromErrno(PyExc_OSError);
- return NULL;
+ return !async_err ? PyErr_SetFromErrno(PyExc_OSError) : NULL;
}
return PyBytes_FromStringAndSize(buf, len);
}
@@ -95,12 +97,13 @@ fcntl_fcntl_impl(PyObject *module, int fd, int code, PyObject *arg)
}
}
- Py_BEGIN_ALLOW_THREADS
- ret = fcntl(fd, code, (int)int_arg);
- Py_END_ALLOW_THREADS
+ do {
+ Py_BEGIN_ALLOW_THREADS
+ ret = fcntl(fd, code, (int)int_arg);
+ Py_END_ALLOW_THREADS
+ } while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
if (ret < 0) {
- PyErr_SetFromErrno(PyExc_OSError);
- return NULL;
+ return !async_err ? PyErr_SetFromErrno(PyExc_OSError) : NULL;
}
return PyLong_FromLong((long)ret);
}
@@ -283,11 +286,14 @@ fcntl_flock_impl(PyObject *module, int fd, int code)
/*[clinic end generated code: output=84059e2b37d2fc64 input=b70a0a41ca22a8a0]*/
{
int ret;
+ int async_err = 0;
#ifdef HAVE_FLOCK
- Py_BEGIN_ALLOW_THREADS
- ret = flock(fd, code);
- Py_END_ALLOW_THREADS
+ do {
+ Py_BEGIN_ALLOW_THREADS
+ ret = flock(fd, code);
+ Py_END_ALLOW_THREADS
+ } while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
#else
#ifndef LOCK_SH
@@ -310,14 +316,15 @@ fcntl_flock_impl(PyObject *module, int fd, int code)
return NULL;
}
l.l_whence = l.l_start = l.l_len = 0;
- Py_BEGIN_ALLOW_THREADS
- ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
- Py_END_ALLOW_THREADS
+ do {
+ Py_BEGIN_ALLOW_THREADS
+ ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
+ Py_END_ALLOW_THREADS
+ } while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
}
#endif /* HAVE_FLOCK */
if (ret < 0) {
- PyErr_SetFromErrno(PyExc_OSError);
- return NULL;
+ return !async_err ? PyErr_SetFromErrno(PyExc_OSError) : NULL;
}
Py_RETURN_NONE;
}
@@ -363,6 +370,7 @@ fcntl_lockf_impl(PyObject *module, int fd, int code, PyObject *lenobj,
/*[clinic end generated code: output=4985e7a172e7461a input=3a5dc01b04371f1a]*/
{
int ret;
+ int async_err = 0;
#ifndef LOCK_SH
#define LOCK_SH 1 /* shared lock */
@@ -407,13 +415,14 @@ fcntl_lockf_impl(PyObject *module, int fd, int code, PyObject *lenobj,
return NULL;
}
l.l_whence = whence;
- Py_BEGIN_ALLOW_THREADS
- ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
- Py_END_ALLOW_THREADS
+ do {
+ Py_BEGIN_ALLOW_THREADS
+ ret = fcntl(fd, (code & LOCK_NB) ? F_SETLK : F_SETLKW, &l);
+ Py_END_ALLOW_THREADS
+ } while (ret == -1 && errno == EINTR && !(async_err = PyErr_CheckSignals()));
}
if (ret < 0) {
- PyErr_SetFromErrno(PyExc_OSError);
- return NULL;
+ return !async_err ? PyErr_SetFromErrno(PyExc_OSError) : NULL;
}
Py_RETURN_NONE;
}
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