[Qemu-block] [PATCH 6/9] iotests: Explicitly inherit FDs in Python

[Max Reitz]

Python 3.2 introduced the inheritable attribute for FDs.  At the same
time, it changed the default so that all FDs are not inheritable by
default, that only inheritable FDs are inherited to subprocesses, and
only if close_fds is explicitly set to False.

Adhere to this by setting close_fds to False when working with
subprocesses that may want to inherit FDs, and by trying to
set_inheritable() on FDs that we do want to bequeath to them.

Signed-off-by: Max Reitz <address@hidden>
---
 scripts/qemu.py        | 13 +++++++++++--
 scripts/qmp/qmp.py     |  7 +++++++
 tests/qemu-iotests/147 |  7 +++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/scripts/qemu.py b/scripts/qemu.py
index f099ce7278..28366c4a67 100644
--- a/scripts/qemu.py
+++ b/scripts/qemu.py
@@ -142,10 +142,18 @@ class QEMUMachine(object):
         if opts:
             options.append(opts)
 
+        # This did not exist before 3.2, but since then it is
+        # mandatory for our purpose
+        try:
+            os.set_inheritable(fd, True)
+        except AttributeError:
+            pass
+
         self._args.append('-add-fd')
         self._args.append(','.join(options))
         return self
 
+    # The caller needs to make sure the FD is inheritable
     def send_fd_scm(self, fd_file_path):
         # In iotest.py, the qmp should always use unix socket.
         assert self._qmp.is_scm_available()
@@ -159,7 +167,7 @@ class QEMUMachine(object):
                     "%s" % fd_file_path]
         devnull = open(os.path.devnull, 'rb')
         proc = subprocess.Popen(fd_param, stdin=devnull, 
stdout=subprocess.PIPE,
-                                stderr=subprocess.STDOUT)
+                                stderr=subprocess.STDOUT, close_fds=False)
         output = proc.communicate()[0]
         if output:
             LOG.debug(output)
@@ -280,7 +288,8 @@ class QEMUMachine(object):
                                        stdin=devnull,
                                        stdout=self._qemu_log_file,
                                        stderr=subprocess.STDOUT,
-                                       shell=False)
+                                       shell=False,
+                                       close_fds=False)
         self._post_launch()
 
     def wait(self):
diff --git a/scripts/qmp/qmp.py b/scripts/qmp/qmp.py
index 5c8cf6a056..009be8345b 100644
--- a/scripts/qmp/qmp.py
+++ b/scripts/qmp/qmp.py
@@ -10,6 +10,7 @@
 
 import json
 import errno
+import os
 import socket
 import logging
 
@@ -253,4 +254,10 @@ class QEMUMonitorProtocol(object):
         return self.__sock.fileno()
 
     def is_scm_available(self):
+        # This did not exist before 3.2, but since then it is
+        # mandatory for our purpose
+        try:
+            os.set_inheritable(self.get_sock_fd(), True)
+        except AttributeError:
+            pass
         return self.__sock.family == socket.AF_UNIX
diff --git a/tests/qemu-iotests/147 b/tests/qemu-iotests/147
index d2081df84b..b58455645b 100755
--- a/tests/qemu-iotests/147
+++ b/tests/qemu-iotests/147
@@ -229,6 +229,13 @@ class BuiltinNBD(NBDBlockdevAddBase):
         sockfd = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
         sockfd.connect(unix_socket)
 
+        # This did not exist before 3.2, but since then it is
+        # mandatory for our purpose
+        try:
+            os.set_inheritable(sockfd.fileno(), True)
+        except AttributeError:
+            pass
+
         result = self.vm.send_fd_scm(str(sockfd.fileno()))
         self.assertEqual(result, 0, 'Failed to send socket FD')
 
-- 
2.17.1