[Qemu-devel] [PATCH v5 4/6] qemu.py: cleanup launch()

[Amador Pahim]

launch() is currently taking care of a number of flows, each one if its
own exception treatment, depending on the VM state and the files
creation state.

This patch makes launch() more resilient, off-loading the core calls to
the new _launch() and calling shutdown() if any exception is raised by
_launch(), making sure VM will be terminated and cleaned up.

Signed-off-by: Amador Pahim <address@hidden>
---
 scripts/qemu.py | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/scripts/qemu.py b/scripts/qemu.py
index 56142ed59b..45a63e8e9d 100644
--- a/scripts/qemu.py
+++ b/scripts/qemu.py
@@ -99,8 +99,11 @@ class QEMUMachine(object):
         return self._popen.pid
 
     def _load_io_log(self):
-        with open(self._qemu_log_path, "r") as fh:
-            self._iolog = fh.read()
+        try:
+            with open(self._qemu_log_path, "r") as fh:
+                self._iolog = fh.read()
+        except IOError:
+            pass
 
     def _base_args(self):
         if isinstance(self._monitor_address, tuple):
@@ -126,23 +129,28 @@ class QEMUMachine(object):
         self._remove_if_exists(self._qemu_log_path)
 
     def launch(self):
-        '''Launch the VM and establish a QMP connection'''
-        devnull = open('/dev/null', 'rb')
-        qemulog = open(self._qemu_log_path, 'wb')
+        '''
+        Try to launch the VM and make sure we cleanup on exception.
+        '''
+        if self.is_running():
+            return
+
         try:
-            self._pre_launch()
-            args = self._wrapper + [self._binary] + self._base_args() + 
self.args
-            self._popen = subprocess.Popen(args, stdin=devnull, stdout=qemulog,
-                                           stderr=subprocess.STDOUT, 
shell=False)
-            self._post_launch()
+            self._launch()
         except:
-            if self.is_running():
-                self._popen.kill()
-                self._popen.wait()
-            self._load_io_log()
-            self._post_shutdown()
+            self.shutdown()
             raise
 
+    def _launch(self):
+        '''Launch the VM and establish a QMP connection.'''
+        devnull = open('/dev/null', 'rb')
+        qemulog = open(self._qemu_log_path, 'wb')
+        self._pre_launch()
+        args = self._wrapper + [self._binary] + self._base_args() + self._args
+        self._popen = subprocess.Popen(args, stdin=devnull, stdout=qemulog,
+                                       stderr=subprocess.STDOUT, shell=False)
+        self._post_launch()
+
     def shutdown(self):
         '''Terminate the VM and clean up'''
         if self.is_running():
@@ -156,8 +164,8 @@ class QEMUMachine(object):
             if exitcode < 0:
                 sys.stderr.write('qemu received signal %i\n' % -exitcode)
 
-            self._load_io_log()
-            self._post_shutdown()
+        self._load_io_log()
+        self._post_shutdown()
 
     underscore_to_dash = string.maketrans('_', '-')
     def qmp(self, cmd, conv_keys=True, **args):
-- 
2.13.3