runqemu: acquire_lock() should fail when failed to open the file

The open(self.lock, 'w') may fail when the lock is created by other
users, return false for this case to let it try other devices.

Fixed:
runqemu - INFO - Running /sbin/ip link...
runqemu - INFO - Acquiring lockfile /tmp/qemu-tap-locks/tap0.lock...
Traceback (most recent call last):
  File "/buildarea/lyang1/poky/scripts/runqemu", line 972, in <module>
    ret = main()
  File "/buildarea/lyang1/poky/scripts/runqemu", line 963, in main
    config.setup_network()
  File "/buildarea/lyang1/poky/scripts/runqemu", line 810, in setup_network
    self.setup_tap()
  File "/buildarea/lyang1/poky/scripts/runqemu", line 761, in setup_tap
    if self.acquire_lock():
  File "/buildarea/lyang1/poky/scripts/runqemu", line 182, in acquire_lock
    lock_descriptor = open(self.lock, 'w')
PermissionError: [Errno 13] Permission denied: '/tmp/qemu-tap-locks/tap0.lock'

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/scripts/runqemu b/scripts/runqemu
index b6bc0ba734..380568560b 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -168,14 +168,14 @@ class BaseConfig(object):
 
     def acquire_lock(self):
         logger.info("Acquiring lockfile %s..." % self.lock)
-        lock_descriptor = open(self.lock, 'w')
         try:
-            fcntl.flock(lock_descriptor, fcntl.LOCK_EX|fcntl.LOCK_NB)
+            self.lock_descriptor = open(self.lock, 'w')
+            fcntl.flock(self.lock_descriptor, fcntl.LOCK_EX|fcntl.LOCK_NB)
         except Exception as e:
             logger.info("Acquiring lockfile %s failed: %s" % (self.lock, e))
-            lock_descriptor.close()
+            if self.lock_descriptor:
+                self.lock_descriptor.close()
             return False
-        self.lock_descriptor = lock_descriptor
         return True
 
     def release_lock(self):