issue6559: Adds a pass_fds parameter to subprocess.Popen that allows the caller
to list exactly which file descriptors should be kept open.
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index ca67012..949c30a 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -608,7 +608,8 @@
preexec_fn=None, close_fds=None, shell=False,
cwd=None, env=None, universal_newlines=False,
startupinfo=None, creationflags=0,
- restore_signals=True, start_new_session=False):
+ restore_signals=True, start_new_session=False,
+ pass_fds=()):
"""Create new Popen instance."""
_cleanup()
@@ -644,6 +645,9 @@
raise ValueError("creationflags is only supported on Windows "
"platforms")
+ if pass_fds and not close_fds:
+ raise ValueError("pass_fds requires close_fds=True.")
+
self.stdin = None
self.stdout = None
self.stderr = None
@@ -671,7 +675,7 @@
errread, errwrite) = self._get_handles(stdin, stdout, stderr)
self._execute_child(args, executable, preexec_fn, close_fds,
- cwd, env, universal_newlines,
+ pass_fds, cwd, env, universal_newlines,
startupinfo, creationflags, shell,
p2cread, p2cwrite,
c2pread, c2pwrite,
@@ -848,7 +852,7 @@
def _execute_child(self, args, executable, preexec_fn, close_fds,
- cwd, env, universal_newlines,
+ pass_fds, cwd, env, universal_newlines,
startupinfo, creationflags, shell,
p2cread, p2cwrite,
c2pread, c2pwrite,
@@ -856,6 +860,8 @@
unused_restore_signals, unused_start_new_session):
"""Execute program (MS Windows version)"""
+ assert not pass_fds, "pass_fds not yet supported on Windows"
+
if not isinstance(args, str):
args = list2cmdline(args)
@@ -1075,8 +1081,19 @@
os.closerange(but + 1, MAXFD)
+ def _close_all_but_a_sorted_few_fds(self, fds_to_keep):
+ # precondition: fds_to_keep must be sorted and unique
+ start_fd = 3
+ for fd in fds_to_keep:
+ if fd > start_fd:
+ os.closerange(start_fd, fd)
+ start_fd = fd + 1
+ if start_fd <= MAXFD:
+ os.closerange(start_fd, MAXFD)
+
+
def _execute_child(self, args, executable, preexec_fn, close_fds,
- cwd, env, universal_newlines,
+ pass_fds, cwd, env, universal_newlines,
startupinfo, creationflags, shell,
p2cread, p2cwrite,
c2pread, c2pwrite,
@@ -1124,9 +1141,11 @@
executable_list = tuple(
os.path.join(os.fsencode(dir), executable)
for dir in os.get_exec_path(env))
+ fds_to_keep = set(pass_fds)
+ fds_to_keep.add(errpipe_write)
self.pid = _posixsubprocess.fork_exec(
args, executable_list,
- close_fds, cwd, env_list,
+ close_fds, sorted(fds_to_keep), cwd, env_list,
p2cread, p2cwrite, c2pread, c2pwrite,
errread, errwrite,
errpipe_read, errpipe_write,
@@ -1180,7 +1199,14 @@
# Close all other fds, if asked for
if close_fds:
- self._close_fds(but=errpipe_write)
+ if pass_fds:
+ fds_to_keep = set(pass_fds)
+ fds_to_keep.add(errpipe_write)
+ self._close_all_but_a_sorted_few_fds(
+ sorted(fds_to_keep))
+ else:
+ self._close_fds(but=errpipe_write)
+
if cwd is not None:
os.chdir(cwd)