[OE-core] [PATCH] buildstats-diff: show more graceful error messages

[liu.ming50 at gmail.com]

From: Ming Liu <peter.x.liu at external.atlascopco.com>

I got a following error when I run buildstats-diff against a invalid
buildstats file:
| Traceback (most recent call last):
|   File "/poky/scripts/buildstats-diff", line 548, in <module>
|     sys.exit(main())
|   File "/poky/scripts/buildstats-diff", line 534, in main
|     bs1 = read_buildstats(args.buildstats1, args.multi)
|   File "/poky/scripts/buildstats-diff", line 222, in read_buildstats
|     return read_buildstats_dir(path)
|   File "/poky/scripts/buildstats-diff", line 165, in read_buildstats_dir
|     os.path.join(recipe_dir, task))]
|   File "/poky/scripts/buildstats-diff", line 124, in read_buildstats_file
|     bs_task['elapsed_time'] = end_time - start_time
| UnboundLocalError: local variable 'end_time' referenced before assignment

the root cause is that a task was terminated by me on the terminal,
so the generated buildstats file was invalid, supposing that it would
make the buildstats.sh fail, but the script should give more graceful
error messages.

Signed-off-by: Ming Liu <peter.x.liu at external.atlascopco.com>
---
 scripts/buildstats-diff | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/buildstats-diff b/scripts/buildstats-diff
index 4276464..8e64480 100755
--- a/scripts/buildstats-diff
+++ b/scripts/buildstats-diff
@@ -97,6 +97,7 @@ def read_buildstats_file(buildstat_file):
     """Convert buildstat text file into dict/json"""
     bs_task = BSTask()
     log.debug("Reading task buildstats from %s", buildstat_file)
+    end_time = None
     with open(buildstat_file) as fobj:
         for line in fobj.readlines():
             key, val = line.split(':', 1)
@@ -121,7 +122,10 @@ def read_buildstats_file(buildstat_file):
                 bs_task[ru_type][ru_key] = val
             elif key == 'Status':
                 bs_task['status'] = val
-    bs_task['elapsed_time'] = end_time - start_time
+    if end_time is not None and start_time is not None:
+        bs_task['elapsed_time'] = end_time - start_time
+    else:
+        raise ScriptError("{} looks like a invalid buildstats file".format(buildstat_file))
     return bs_task
 
 
-- 
2.7.4