reintroduce create_skipfile.py script for gerrit

[gyorb]

The script was removed in c1626bb
but for the usecase where the user does not want to analyze
all the source files in the review it is needed.

[csordasmarton]

Inside the common library there is already a similar function to get the list of changed files:

codechecker/codechecker_common/output/gerrit.py

Lines 107 to 138 in 0be059e

	def __get_changed_files(changed_file_path: Union[None, str]) -> List[str]:
	"""Return a list of changed files.
	Process the given gerrit changed file object and return a list of
	file paths which changed.
	The file can contain some garbage values at start, so we use regex
	to find a json object.
	"""
	changed_files = []
	if not changed_file_path or not os.path.exists(changed_file_path):
	return changed_files
	with open(changed_file_path,
	encoding='utf-8',
	errors='ignore') as changed_file:
	content = changed_file.read()
	# The file can contain some garbage values at start, so we use
	# regex search to find a json object.
	match = re.search(r'\{[\s\S]*\}', content)
	if not match:
	return changed_files
	for filename in json.loads(match.group(0)):
	if "/COMMIT_MSG" in filename:
	continue
	changed_files.append(filename)
	return changed_files

Because you created a module in this PR I recommend you to move this function under this tool so we can use this in two places and we can avoid code duplication:

• you can use this __get_changed_files function to create skip file in this tool.
• and you can use this function in the common module.

[csordasmarton]

Please follow the structure of our other tools:

• create a readme in the root directory of the tool which describe what this tool does, how you can use it and maybe an example.
• create a codechecker_skiplist directory which will be a module and you move this file also to this directory. So in the CodeChecker we can import and use it.
• I recommend you to rename this file because from the path (tools/skiplist/create_skipfile.py ) for example I can't figure out that this tool is for gerrit integration. So for example the gerrit_changed_files_to_skipfile or something similar would be a better name choice.

[gyorb]

I've moved it under the scripts directory as we discussed this will not be a separate tool yet.
I thought about moving it under the bin directory but in that case the create_commands.py script needs to be further complicated and I'm not sure we want that.

[csordasmarton]

Do not we need to use python3 binary here? For example in the Makefiles we are using python3 binary.

[gyorb]

What if the jenkins environment has only python2?

[csordasmarton]

Suggested change

	# -------------------------------------------------------------------------
	#!/usr/bin/env python3
	# -------------------------------------------------------------------------

[gyorb]

Yes I thought about it but the script is python2/python3 compatible now, with that change we limit it to python3 only do we want that?

[csordasmarton]

If we specify the interpreter in the python file below we can copy it without the .py extension so this command can be called easily.
Also other commands in the bin directory doesn't have extension so it would be more consistent and the user doesn't have to call this script through the python binary.

[gyorb]

Yes, the same reason I did not this change what I described in my previous answer. I thought about it but the script is python2/python3 compatible now, with that change we limit it to python3 only do we want that?

[csordasmarton]

LGTM!