[lldb/crashlog] Refactor CrashLogParser into a Factory pattern

[mib]

Summary

This patch should fix an undefined behaviour that's happening when
parsing a crash report from an IDE. In the previous implementation, the
CrashLogParser base class would use the __new__ static class method to
create the right parser instance depending on the crash report type.

For some reasons, the derived parser initializer wouldn't be called when
running the command from an IDE, so this patch refactors the
CrashLogParser code to replace the use of the __new__ method with a
factory create static method.

rdar://100527640

Signed-off-by: Med Ismail Bennani <[e-mail]>

[JDevlieghere]

lldb/examples/python/crashlog.py

428–429

This looks like a class now. The common patter for a factory is to create a static method (e.g. create) in the class you're instantiating.

[kastiglione]

lldb/examples/python/crashlog.py

428–429

+1

[mib]

Address @kastiglione & @JDevlieghere comments:

• rename the factory method to create

[JDevlieghere]

Ship it

lldb/examples/python/crashlog.py

 
 class CrashLogParseException(Exception):
     pass
 
 class InteractiveCrashLogException(Exception):
     pass
 
 class CrashLogParser:
-    "CrashLog parser base class and factory."
-    def __new__(cls, debugger, path, verbose):
+    @staticmethod
+    def create(debugger, path, verbose):
         data = JSONCrashLogParser.is_valid_json(path)
         if data:
-            self = object.__new__(JSONCrashLogParser)
-            self.data = data
-            return self
+            parser = JSONCrashLogParser(debugger, path, verbose)
+            parser.data = data
+            return parser
         else:
-            return object.__new__(TextCrashLogParser)
+            return TextCrashLogParser(debugger, path, verbose)
 
     def __init__(self, debugger, path, verbose):
         self.path = os.path.expanduser(path)
         self.verbose = verbose
         self.crashlog = CrashLog(debugger, self.path, self.verbose)
 
     @abc.abstractmethod
     def parse(self):
         pass
if crash_log.errors:
         for error in crash_log.errors:
             print(error)
 
 def load_crashlog_in_scripted_process(debugger, crash_log_file, options, result):
     crashlog_path = os.path.expanduser(crash_log_file)
     if not os.path.exists(crashlog_path):
         raise InteractiveCrashLogException("crashlog file %s does not exist" % crashlog_path)
 
-    crashlog = CrashLogParser(debugger, crashlog_path, False).parse()
+    crashlog = CrashLogParser.create(debugger, crashlog_path, False).parse()
 
     target = lldb.SBTarget()
     # 1. Try to use the user-provided target
     if options.target_path:
         target = debugger.CreateTarget(options.target_path)
         if not target:
             raise InteractiveCrashLogException("couldn't create target provided by the user (%s)" % options.target_path)
 
if args:
         for crash_log_file in args:
             if should_run_in_interactive_mode(options, ci):
                 try:
                     load_crashlog_in_scripted_process(debugger, crash_log_file,
                                                       options, result)
                 except InteractiveCrashLogException as e:
                     result.SetError(str(e))
             else:
-                crash_log = CrashLogParser(debugger, crash_log_file, options.verbose).parse()
+                crash_log = CrashLogParser.create(debugger, crash_log_file, options.verbose).parse()
                 SymbolicateCrashLog(crash_log, options)
 
 if __name__ == '__main__':
     # Create a new debugger instance
     debugger = lldb.SBDebugger.Create()
     result = lldb.SBCommandReturnObject()
     SymbolicateCrashLogs(debugger, sys.argv[1:], result)
     lldb.SBDebugger.Destroy(debugger)
 
 def __lldb_init_module(debugger, internal_dict):
     debugger.HandleCommand(
         'command script add -c lldb.macosx.crashlog.Symbolicate crashlog')
     debugger.HandleCommand(
         'command script add -f lldb.macosx.crashlog.save_crashlog save_crashlog')
     print('"crashlog" and "save_crashlog" commands have been installed, use '
           'the "--help" options on these commands for detailed help.')

lldb/examples/python/scripted_process/crashlog_scripted_process.py

 import os,json,struct,signal,uuid
 
 from typing import Any, Dict
 
 import lldb
 from lldb.plugins.scripted_process import ScriptedProcess
 from lldb.plugins.scripted_process import ScriptedThread
 
 from lldb.macosx.crashlog import CrashLog,CrashLogParser
 
 class CrashLogScriptedProcess(ScriptedProcess):
     def parse_crashlog(self):
-        crashlog_parser = CrashLogParser(self.dbg, self.crashlog_path, False)
+        crashlog_parser = CrashLogParser.create(self.dbg, self.crashlog_path, False)
         crash_log = crashlog_parser.parse()
 
         self.pid = crash_log.process_id
         self.addr_mask = crash_log.addr_mask
         self.crashed_thread_idx = crash_log.crashed_thread_idx
         self.loaded_images = []
         self.exception = crash_log.exception
         self.app_specific_thread = None