From 53dd8167ff548233373a75c4884ae5490b91f010 Mon Sep 17 00:00:00 2001 From: "Gregory P. Smith" Date: Sun, 1 Dec 2013 16:03:24 -0800 Subject: [PATCH] Fixes issue #15798: subprocess.Popen() no longer fails if file descriptor 0, 1 or 2 is closed. (correct fix for 3.4 this time) --- Lib/subprocess.py | 7 +++++++ Lib/test/test_subprocess.py | 21 +++++++++++++++++++++ Misc/NEWS | 3 +++ 3 files changed, 31 insertions(+) diff --git a/Lib/subprocess.py b/Lib/subprocess.py index 88355ada1b..0942d94ef7 100644 --- a/Lib/subprocess.py +++ b/Lib/subprocess.py @@ -1341,6 +1341,13 @@ class Popen(object): # 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 index 54f648265f..46e012d142 100644 --- a/Lib/test/test_subprocess.py +++ b/Lib/test/test_subprocess.py @@ -1559,6 +1559,27 @@ class POSIXProcessTestCase(BaseTestCase): # 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 index 4a837d476b..47579cbba3 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -18,6 +18,9 @@ Core and Builtins 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() -- 2.40.0