Issue #10806, issue #9905: Fix subprocess pipes when some of the standard
file descriptors (0, 1, 2) are closed in the parent process. Initial
patch by Ross Lagerwall.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index c12898d..7d3f77f 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -393,22 +393,22 @@
# POSIX defines PIPE_BUF as >= 512.
_PIPE_BUF = getattr(select, 'PIPE_BUF', 512)
+ _FD_CLOEXEC = getattr(fcntl, 'FD_CLOEXEC', 1)
+
+ def _set_cloexec(fd, cloexec):
+ old = fcntl.fcntl(fd, fcntl.F_GETFD)
+ if cloexec:
+ fcntl.fcntl(fd, fcntl.F_SETFD, old | _FD_CLOEXEC)
+ else:
+ fcntl.fcntl(fd, fcntl.F_SETFD, old & ~_FD_CLOEXEC)
+
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)
-
+ _set_cloexec(fds[0], True)
+ _set_cloexec(fds[1], True)
return fds
__all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput",
@@ -1194,23 +1194,25 @@
os.close(errpipe_read)
# Dup fds for child
- if p2cread != -1:
- os.dup2(p2cread, 0)
- if c2pwrite != -1:
- os.dup2(c2pwrite, 1)
- if errwrite != -1:
- os.dup2(errwrite, 2)
+ def _dup2(a, b):
+ # dup2() removes the CLOEXEC flag but
+ # we must do it ourselves if dup2()
+ # would be a no-op (issue #10806).
+ if a == b:
+ _set_cloexec(a, False)
+ elif a != -1:
+ os.dup2(a, b)
+ _dup2(p2cread, 0)
+ _dup2(c2pwrite, 1)
+ _dup2(errwrite, 2)
# Close pipe fds. Make sure we don't close the
# same fd more than once, or standard fds.
- if p2cread != -1 and p2cread not in (0,):
- os.close(p2cread)
- if (c2pwrite != -1 and
- c2pwrite not in (p2cread, 1)):
- os.close(c2pwrite)
- if (errwrite != -1 and
- errwrite not in (p2cread, c2pwrite, 2)):
- os.close(errwrite)
+ closed = set()
+ for fd in [p2cread, c2pwrite, errwrite]:
+ if fd > 2 and fd not in closed:
+ os.close(fd)
+ closed.add(fd)
# Close all other fds, if asked for
if close_fds:
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 8b2699d..7b9e2b4 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -903,6 +903,58 @@
self.assertStderrEqual(stderr, b'')
self.assertEqual(p.wait(), -signal.SIGTERM)
+ def check_close_std_fds(self, fds):
+ # Issue #9905: test that subprocess pipes still work properly with
+ # some standard fds closed
+ stdin = 0
+ newfds = []
+ for a in fds:
+ b = os.dup(a)
+ newfds.append(b)
+ if a == 0:
+ stdin = b
+ try:
+ for fd in fds:
+ os.close(fd)
+ out, err = subprocess.Popen([sys.executable, "-c",
+ 'import sys;'
+ 'sys.stdout.write("apple");'
+ 'sys.stdout.flush();'
+ 'sys.stderr.write("orange")'],
+ stdin=stdin,
+ stdout=subprocess.PIPE,
+ stderr=subprocess.PIPE).communicate()
+ err = support.strip_python_stderr(err)
+ self.assertEqual((out, err), (b'apple', b'orange'))
+ finally:
+ for b, a in zip(newfds, fds):
+ os.dup2(b, a)
+ for b in newfds:
+ os.close(b)
+
+ def test_close_fd_0(self):
+ self.check_close_std_fds([0])
+
+ def test_close_fd_1(self):
+ self.check_close_std_fds([1])
+
+ def test_close_fd_2(self):
+ self.check_close_std_fds([2])
+
+ def test_close_fds_0_1(self):
+ self.check_close_std_fds([0, 1])
+
+ def test_close_fds_0_2(self):
+ self.check_close_std_fds([0, 2])
+
+ def test_close_fds_1_2(self):
+ self.check_close_std_fds([1, 2])
+
+ def test_close_fds_0_1_2(self):
+ # Issue #10806: test that subprocess pipes still work properly with
+ # all standard fds closed.
+ self.check_close_std_fds([0, 1, 2])
+
def test_surrogates_error_message(self):
def prepare():
raise ValueError("surrogate:\uDCff")