[1/9] simpletrace: Improve parsing of sys.argv; fix files never closed.

Commit Message

Mads Ynddal Feb. 21, 2023, 9 a.m. UTC

From: Mads Ynddal <[e-mail]>

The arguments extracted from `sys.argv` named and unpacked to make it
clear what the arguments are and what they're used for.

The two input files were opened, but never explicitly closed. File usage
changed to use `with` statement to take care of this. At the same time,
ownership of the file-object is moved up to `run` function. Secondary `open`
inside `process` removed so there's only one place to handle `open`.

Signed-off-by: Mads Ynddal <[e-mail]>
---
 scripts/simpletrace.py | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

Patch

diff --git a/scripts/simpletrace.py b/scripts/simpletrace.py
index 1f6d1ae1f3..9211caaec1 100755
--- a/scripts/simpletrace.py
+++ b/scripts/simpletrace.py
@@ -9,6 +9,7 @@ 
 #
 # For help see docs/devel/tracing.rst
 
+import sys
 import struct
 import inspect
 from tracetool import read_events, Event
@@ -44,7 +45,6 @@  def get_record(edict, idtoname, rechdr, fobj):
         try:
             event = edict[name]
         except KeyError as e:
-            import sys
             sys.stderr.write('%s event is logged but is not declared ' \
                              'in the trace events file, try using ' \
                              'trace-events-all instead.\n' % str(e))
@@ -166,11 +166,6 @@  def end(self):
 
 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)
-    if isinstance(log, str):
-        log = open(log, 'rb')
-
     if read_header:
         read_trace_header(log)
 
@@ -223,19 +218,18 @@  def run(analyzer):
 
     This function is useful as a driver for simple analysis scripts.  More
     advanced scripts will want to call process() instead."""
-    import sys
-
-    read_header = True
-    if len(sys.argv) == 4 and sys.argv[1] == '--no-header':
-        read_header = False
-        del sys.argv[1]
-    elif len(sys.argv) != 3:
-        sys.stderr.write('usage: %s [--no-header] <trace-events> ' \
-                         '<trace-file>\n' % sys.argv[0])
+
+    try:
+        # NOTE: See built-in `argparse` module for a more robust cli interface
+        *no_header, trace_event_path, trace_file_path = sys.argv[1:]
+        assert no_header == [] or no_header == ['--no-header'], 'Invalid no-header argument'
+    except (AssertionError, ValueError):
+        sys.stderr.write(f'usage: {sys.argv[0]} [--no-header] <trace-events> <trace-file>\n')
         sys.exit(1)
 
-    events = read_events(open(sys.argv[1], 'r'), sys.argv[1])
-    process(events, sys.argv[2], analyzer, read_header=read_header)
+    with open(trace_event_path, 'r') as events_fobj, open(trace_file_path, 'rb') as log_fobj:
+        events = read_events(events_fobj, trace_event_path)
+        process(events, log_fobj, analyzer, read_header=not no_header)
 
 if __name__ == '__main__':
     class Formatter(Analyzer):