[Qemu-devel] [PATCH v8 06/13] qemu.py: make sure we only remove files we create

[Amador Pahim <apahim@redhat.com>]

To launch a VM, we need to create basically two files: the monitor
socket (if it's a UNIX socket) and the qemu log file.

For the qemu log file, we currently just open the path, which will
create the file if it does not exist or overwrite the file if it does
exist.

For the monitor socket, if it already exists, we are currently removing
it, even if it's not created by us.

This patch moves to pre_launch() the responsibility to make sure we only
create files that are not pre-existent and to populate a list of
controlled files. This list will then be used as the reference of
files to remove during the cleanup (post_shutdown()).

Signed-off-by: Amador Pahim <apahim@redhat.com>
---
 scripts/qemu.py | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/scripts/qemu.py b/scripts/qemu.py
index 3ebe5ee0a4..c26e1412f9 100644
--- a/scripts/qemu.py
+++ b/scripts/qemu.py
@@ -41,6 +41,7 @@ class QEMUMachine(object):
             monitor_address = os.path.join(test_dir, name + "-monitor.sock")
         self._monitor_address = monitor_address
         self._qemu_log_path = os.path.join(test_dir, name + ".log")
+        self._qemu_log_fd = None
         self._popen = None
         self._binary = binary
         self._args = list(args) # Force copy args in case we modify them
@@ -50,6 +51,7 @@ class QEMUMachine(object):
         self._socket_scm_helper = socket_scm_helper
         self._debug = debug
         self._qemu_full_args = None
+        self._created_files = []
 
     # This can be used to add an unused monitor instance.
     def add_monitor_telnet(self, ip, port):
@@ -128,30 +130,44 @@ class QEMUMachine(object):
                 '-display', 'none', '-vga', 'none']
 
     def _pre_launch(self):
-        self._qmp = qmp.qmp.QEMUMonitorProtocol(self._monitor_address, server=True,
-                                                debug=self._debug)
+        try:
+            self._qmp = qmp.qmp.QEMUMonitorProtocol(self._monitor_address,
+                                                    server=True,
+                                                    debug=self._debug)
+        except:
+            raise
+        else:
+            if not isinstance(self._monitor_address, tuple):
+                self._created_files.append(self._monitor_address)
+
+        try:
+            flags = os.O_CREAT | os.O_EXCL | os.O_WRONLY
+            os.open(self._qemu_log_path, flags)
+        except:
+            raise
+        else:
+            self._created_files.append(self._qemu_log_path)
+            self._qemu_log_fd = open(self._qemu_log_path, 'wb')
 
     def _post_launch(self):
         self._qmp.accept()
 
     def _post_shutdown(self):
-        if not isinstance(self._monitor_address, tuple):
-            self._remove_if_exists(self._monitor_address)
-        self._remove_if_exists(self._qemu_log_path)
+        while self._created_files:
+            self._remove_if_exists(self._created_files.pop())
 
     def launch(self):
         '''Launch the VM and establish a QMP connection'''
         self._iolog = None
         self._qemu_full_args = None
         devnull = open(os.path.devnull, 'rb')
-        qemulog = open(self._qemu_log_path, 'wb')
         try:
             self._pre_launch()
             self._qemu_full_args = (self._wrapper + [self._binary] +
                                     self._base_args() + self._args)
             self._popen = subprocess.Popen(self._qemu_full_args,
                                            stdin=devnull,
-                                           stdout=qemulog,
+                                           stdout=self._qemu_log_fd,
                                            stderr=subprocess.STDOUT,
                                            shell=False)
             self._post_launch()
-- 
2.13.5