[Python-checkins] cpython: Fixes issue #15798: subprocess.Popen() no longer fails if file

Mon Dec 2 01:03:44 CET 2013

http://hg.python.org/cpython/rev/2df5e1f537b0
changeset: 87683:2df5e1f537b0
user: Gregory P. Smith <greg at krypto.org>
date: Sun Dec 01 16:03:24 2013 -0800
summary:
 Fixes issue #15798: subprocess.Popen() no longer fails if file
descriptor 0, 1 or 2 is closed. (correct fix for 3.4 this time)
files:
 Lib/subprocess.py | 7 +++++++
 Lib/test/test_subprocess.py | 21 +++++++++++++++++++++
 Misc/NEWS | 3 +++
 3 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/Lib/subprocess.py b/Lib/subprocess.py
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1341,6 +1341,13 @@
 # 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_write must not be in the standard io 0, 1, or 2 fd range.
+ low_fds_to_close = []
+ while errpipe_write < 3:
+ low_fds_to_close.append(errpipe_write)
+ errpipe_write = os.dup(errpipe_write)
+ for low_fd in low_fds_to_close:
+ os.close(low_fd)
 try:
 try:
 # We must avoid complex work that could involve
diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1559,6 +1559,27 @@
 # all standard fds closed.
 self.check_close_std_fds([0, 1, 2])
 
+ def test_small_errpipe_write_fd(self):
+ """Issue #15798: Popen should work when stdio fds are available."""
+ new_stdin = os.dup(0)
+ new_stdout = os.dup(1)
+ try:
+ os.close(0)
+ os.close(1)
+
+ # Side test: if errpipe_write fails to have its CLOEXEC
+ # flag set this should cause the parent to think the exec
+ # failed. Extremely unlikely: everyone supports CLOEXEC.
+ subprocess.Popen([
+ sys.executable, "-c",
+ "print('AssertionError:0:CLOEXEC failure.')"]).wait()
+ finally:
+ # Restore original stdin and stdout
+ os.dup2(new_stdin, 0)
+ os.dup2(new_stdout, 1)
+ os.close(new_stdin)
+ os.close(new_stdout)
+
 def test_remapping_std_fds(self):
 # open up some temporary files
 temps = [mkstemp() for i in range(3)]
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -18,6 +18,9 @@
 Library
 -------
 
+- Issue #15798: Fixed subprocess.Popen() to no longer fail if file
+ descriptor 0, 1 or 2 is closed.
+
 - Issue #17897: Optimized unpickle prefetching.
 
 - Issue #3693: Make the error message more helpful when the array.array()
-- 
Repository URL: http://hg.python.org/cpython
