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Prevent a possible double close of parent pipe fds when the subprocess 

exec runs into an error.  Prevent a regular multi-close of the /dev/null
fd when any of stdin, stdout and stderr was set to DEVNULL.
This commit is contained in:
Gregory P. Smith 2013-06-15 18:04:26 -07:00
parent 53e5ea7951
commit b5461b9884
1 changed files with 25 additions and 18 deletions
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43
Lib/subprocess.py
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@ -810,6 +810,7 @@ class Popen(object):
if universal_newlines:
self.stderr = io.TextIOWrapper(self.stderr)
self._closed_child_pipe_fds = False
try:
self._execute_child(args, executable, preexec_fn, close_fds,
pass_fds, cwd, env,
@ -826,19 +827,21 @@ class Popen(object):
except EnvironmentError:
pass # Ignore EBADF or other errors.
# Make sure the child pipes are closed as well.
to_close = []
if stdin == PIPE:
to_close.append(p2cread)
if stdout == PIPE:
to_close.append(c2pwrite)
if stderr == PIPE:
to_close.append(errwrite)
for fd in to_close:
try:
os.close(fd)
except EnvironmentError:
pass
if not self._closed_child_pipe_fds:
to_close = []
if stdin == PIPE:
to_close.append(p2cread)
if stdout == PIPE:
to_close.append(c2pwrite)
if stderr == PIPE:
to_close.append(errwrite)
if hasattr(self, '_devnull'):
to_close.append(self._devnull)
for fd in to_close:
try:
os.close(fd)
except EnvironmentError:
pass
raise
@ -1383,14 +1386,18 @@ class Popen(object):
# be sure the FD is closed no matter what
os.close(errpipe_write)
if p2cread != -1 and p2cwrite != -1:
# self._devnull is not always defined.
devnull_fd = getattr(self, '_devnull', None)
if p2cread != -1 and p2cwrite != -1 and p2cread != devnull_fd:
os.close(p2cread)
if c2pwrite != -1 and c2pread != -1:
if c2pwrite != -1 and c2pread != -1 and c2pwrite != devnull_fd:
os.close(c2pwrite)
if errwrite != -1 and errread != -1:
if errwrite != -1 and errread != -1 and errwrite != devnull_fd:
os.close(errwrite)
if hasattr(self, '_devnull'):
os.close(self._devnull)
if devnull_fd is not None:
os.close(devnull_fd)
# Prevent a double close of these fds from __init__ on error.
self._closed_child_pipe_fds = True
# Wait for exec to fail or succeed; possibly raising an
# exception (limited in size)