trace: include filename when printing parser error messages

Improves error messages from:

ValueError: Error on line 72: need more than 1 value to unpack

To

ValueError: Error at /home/berrange/src/virt/qemu/trace-events:72:
need more than 1 value to unpack

Signed-off-by Daniel P. Berrangé <[email protected]>

---
 scripts/simpletrace.py        | 4 ++--
 scripts/tracetool.py          | 2 +-
 scripts/tracetool/__init__.py | 6 ++++--
 3 files changed, 7 insertions(+), 5 deletions(-)

scripts/simpletrace.py +2 -2

index a3a6315055..fefc0806b8 100755
@@ -168,7 +168,7 @@ class Analyzer(object):
 def process(events, log, analyzer, read_header=True):
     """Invoke an analyzer on each event in a log."""
     if isinstance(events, str):
-        events = read_events(open(events, 'r'))
+        events = read_events(open(events, 'r'), events)
     if isinstance(log, str):
         log = open(log, 'rb')
 

@@ -233,7 +233,7 @@ def run(analyzer):
                          '<trace-file>\n' % sys.argv[0])
         sys.exit(1)
 
-    events = read_events(open(sys.argv[1], 'r'))
+    events = read_events(open(sys.argv[1], 'r'), sys.argv[1])
     process(events, sys.argv[2], analyzer, read_header=read_header)
 
 if __name__ == '__main__':

scripts/tracetool.py +1 -1

index c55a21518b..fe2b0771f2 100755
@@ -142,7 +142,7 @@ def main(args):
     events = []
     for arg in args:
         with open(arg, "r") as fh:
-            events.extend(tracetool.read_events(fh))
+            events.extend(tracetool.read_events(fh, arg))
 
     try:
         tracetool.generate(events, arg_group, arg_format, arg_backends,

scripts/tracetool/__init__.py +4 -2

index 52cc687ae3..b645be30d1 100644
@@ -336,13 +336,15 @@ class Event(object):
                      self)
 
 
-def read_events(fobj):
+def read_events(fobj, fname):
     """Generate the output for the given (format, backends) pair.
 
     Parameters
     ----------
     fobj : file
         Event description file.
+    fname : str
+        Name of event file
 
     Returns a list of Event objects
     """

@@ -357,7 +359,7 @@ def read_events(fobj):
         try:
             event = Event.build(line)
         except ValueError as e:
-            arg0 = 'Error on line %d: %s' % (lineno, e.args[0])
+            arg0 = 'Error at %s:%d: %s' % (fname, lineno, e.args[0])
             e.args = (arg0,) + e.args[1:]
             raise
 

Improves error messages from:

ValueError: Error on line 72: need more than 1 value to unpack

To

ValueError: Error at /home/berrange/src/virt/qemu/trace-events:72:
need more than 1 value to unpack

Signed-off-by Daniel P. Berrangé <[email protected]>

---
 scripts/simpletrace.py        | 4 ++--
 scripts/tracetool.py          | 2 +-
 scripts/tracetool/__init__.py | 6 ++++--
 3 files changed, 7 insertions(+), 5 deletions(-)