issue7213: Open the pipes used by subprocesses with the FD_CLOEXEC flag from
the C code, using pipe2() when available. Adds unittests for close_fds and
cloexec behaviors.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 62dfd36..729a53b 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -390,6 +390,23 @@
# POSIX defines PIPE_BUF as >= 512.
_PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
+ if _posixsubprocess:
+ _create_pipe = _posixsubprocess.cloexec_pipe
+ else:
+ def _create_pipe():
+ try:
+ cloexec_flag = fcntl.FD_CLOEXEC
+ except AttributeError:
+ cloexec_flag = 1
+
+ fds = os.pipe()
+
+ old = fcntl.fcntl(fds[0], fcntl.F_GETFD)
+ fcntl.fcntl(fds[0], fcntl.F_SETFD, old | cloexec_flag)
+ old = fcntl.fcntl(fds[1], fcntl.F_GETFD)
+ fcntl.fcntl(fds[1], fcntl.F_SETFD, old | cloexec_flag)
+
+ return fds
__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
"getoutput", "check_output", "CalledProcessError"]
@@ -1031,7 +1048,7 @@
if stdin is None:
pass
elif stdin == PIPE:
- p2cread, p2cwrite = os.pipe()
+ p2cread, p2cwrite = _create_pipe()
elif isinstance(stdin, int):
p2cread = stdin
else:
@@ -1041,7 +1058,7 @@
if stdout is None:
pass
elif stdout == PIPE:
- c2pread, c2pwrite = os.pipe()
+ c2pread, c2pwrite = _create_pipe()
elif isinstance(stdout, int):
c2pwrite = stdout
else:
@@ -1051,7 +1068,7 @@
if stderr is None:
pass
elif stderr == PIPE:
- errread, errwrite = os.pipe()
+ errread, errwrite = _create_pipe()
elif stderr == STDOUT:
errwrite = c2pwrite
elif isinstance(stderr, int):
@@ -1065,16 +1082,6 @@
errread, errwrite)
- def _set_cloexec_flag(self, fd):
- try:
- cloexec_flag = fcntl.FD_CLOEXEC
- except AttributeError:
- cloexec_flag = 1
-
- old = fcntl.fcntl(fd, fcntl.F_GETFD)
- fcntl.fcntl(fd, fcntl.F_SETFD, old | cloexec_flag)
-
-
def _close_fds(self, but):
os.closerange(3, but)
os.closerange(but + 1, MAXFD)
@@ -1116,10 +1123,9 @@
# For transferring possible exec failure from child to parent.
# Data format: "exception name:hex errno:description"
# Pickle is not used; it is complex and involves memory allocation.
- errpipe_read, errpipe_write = os.pipe()
+ errpipe_read, errpipe_write = _create_pipe()
try:
try:
- self._set_cloexec_flag(errpipe_write)
if _posixsubprocess:
# We must avoid complex work that could involve
diff --git a/Lib/test/subprocessdata/fd_status.py b/Lib/test/subprocessdata/fd_status.py
new file mode 100644
index 0000000..083b2f9
--- /dev/null
+++ b/Lib/test/subprocessdata/fd_status.py
@@ -0,0 +1,24 @@
+"""When called as a script, print a comma-separated list of the open
+file descriptors on stdout."""
+
+import errno
+import os
+import fcntl
+
+try:
+ _MAXFD = os.sysconf("SC_OPEN_MAX")
+except:
+ _MAXFD = 256
+
+def isopen(fd):
+ """Return True if the fd is open, and False otherwise"""
+ try:
+ fcntl.fcntl(fd, fcntl.F_GETFD, 0)
+ except IOError as e:
+ if e.errno == errno.EBADF:
+ return False
+ raise
+ return True
+
+if __name__ == "__main__":
+ print(','.join(str(fd) for fd in range(0, _MAXFD) if isopen(fd)))
diff --git a/Lib/test/subprocessdata/input_reader.py b/Lib/test/subprocessdata/input_reader.py
new file mode 100644
index 0000000..ccae5f3
--- /dev/null
+++ b/Lib/test/subprocessdata/input_reader.py
@@ -0,0 +1,7 @@
+"""When called as a script, consumes the input"""
+
+import sys
+
+if __name__ = "__main__":
+ for line in sys.stdin:
+ pass
diff --git a/Lib/test/subprocessdata/qcat.py b/Lib/test/subprocessdata/qcat.py
new file mode 100644
index 0000000..fe6f9db
--- /dev/null
+++ b/Lib/test/subprocessdata/qcat.py
@@ -0,0 +1,7 @@
+"""When ran as a script, simulates cat with no arguments."""
+
+import sys
+
+if __name__ == "__main__":
+ for line in sys.stdin:
+ sys.stdout.write(line)
diff --git a/Lib/test/subprocessdata/qgrep.py b/Lib/test/subprocessdata/qgrep.py
new file mode 100644
index 0000000..6990637
--- /dev/null
+++ b/Lib/test/subprocessdata/qgrep.py
@@ -0,0 +1,10 @@
+"""When called with a single argument, simulated fgrep with a single
+argument and no options."""
+
+import sys
+
+if __name__ == "__main__":
+ pattern = sys.argv[1]
+ for line in sys.stdin:
+ if pattern in line:
+ sys.stdout.write(line)
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index eaa26d2..74e7404 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -10,6 +10,7 @@
import re
import sysconfig
import warnings
+import select
try:
import gc
except ImportError:
@@ -964,6 +965,83 @@
exitcode = subprocess.call([program, "-c", "pass"], env=envb)
self.assertEqual(exitcode, 0)
+ def test_pipe_cloexec(self):
+ sleeper = support.findfile("input_reader.py", subdir="subprocessdata")
+ fd_status = support.findfile("fd_status.py", subdir="subprocessdata")
+
+ p1 = subprocess.Popen([sys.executable, sleeper],
+ stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE, close_fds=False)
+
+ self.addCleanup(p1.communicate, b'')
+
+ p2 = subprocess.Popen([sys.executable, fd_status],
+ stdout=subprocess.PIPE, close_fds=False)
+
+ output, error = p2.communicate()
+ result_fds = set(map(int, output.split(b',')))
+ unwanted_fds = set([p1.stdin.fileno(), p1.stdout.fileno(),
+ p1.stderr.fileno()])
+
+ self.assertFalse(result_fds & unwanted_fds,
+ "Expected no fds from %r to be open in child, "
+ "found %r" %
+ (unwanted_fds, result_fds & unwanted_fds))
+
+ def test_pipe_cloexec_real_tools(self):
+ qcat = support.findfile("qcat.py", subdir="subprocessdata")
+ qgrep = support.findfile("qgrep.py", subdir="subprocessdata")
+
+ subdata = b'zxcvbn'
+ data = subdata * 4 + b'\n'
+
+ p1 = subprocess.Popen([sys.executable, qcat],
+ stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+ close_fds=False)
+
+ p2 = subprocess.Popen([sys.executable, qgrep, subdata],
+ stdin=p1.stdout, stdout=subprocess.PIPE,
+ close_fds=False)
+
+ self.addCleanup(p1.wait)
+ self.addCleanup(p2.wait)
+ self.addCleanup(p1.terminate)
+ self.addCleanup(p2.terminate)
+
+ p1.stdin.write(data)
+ p1.stdin.close()
+
+ readfiles, ignored1, ignored2 = select.select([p2.stdout], [], [], 10)
+
+ self.assertTrue(readfiles, "The child hung")
+ self.assertEqual(p2.stdout.read(), data)
+
+ def test_close_fds(self):
+ fd_status = support.findfile("fd_status.py", subdir="subprocessdata")
+
+ fds = os.pipe()
+ self.addCleanup(os.close, fds[0])
+ self.addCleanup(os.close, fds[1])
+
+ open_fds = set(fds)
+
+ p = subprocess.Popen([sys.executable, fd_status],
+ stdout=subprocess.PIPE, close_fds=False)
+ output, ignored = p.communicate()
+ remaining_fds = set(map(int, output.split(b',')))
+
+ self.assertEqual(remaining_fds & open_fds, open_fds,
+ "Some fds were closed")
+
+ p = subprocess.Popen([sys.executable, fd_status],
+ stdout=subprocess.PIPE, close_fds=True)
+ output, ignored = p.communicate()
+ remaining_fds = set(map(int, output.split(b',')))
+
+ self.assertFalse(remaining_fds & open_fds,
+ "Some fds were left open")
+ self.assertIn(1, remaining_fds, "Subprocess failed")
+
@unittest.skipUnless(mswindows, "Windows specific tests")
class Win32ProcessTestCase(BaseTestCase):