Feature/INTEG_978 handle keyboard interrupts (#60)

* update ArgConfig to allow changing metavar setting

* move verify_timestamp_order to date_helper module

* - add AlertCursorStore class
- refactor shared methods onto the base class
- set default db name to "checkpoints.db" so we don't create separate dbs for each cursor store

* - moved enums to shared module
- added Alert enums

* pull out shared extraction functions

* move logger_factory to shared module

* update securitydata extraction and main

* add alerts extraction and main

* add main alerts command

* update setup.py

* update some tests

* update conftest

* bump dependency versions

* fix bugs in advanced_arg handling

* extract shared search arguments into shared module

* complete the warning change

* fixed existing tests

* fixed global error state flagging

* rename shared func

* more test fixes

* Remove CEF option for alerts output

* hard-code cursor_store db to `file_event_checkpoints.db`

* update profile deletion to handle alert cursors

* fix log method docstrings

* fix import

* logging adjustments

* add new logging to alert extraction

* update shared extraction logging

* improve error handling

* fix file event tests with new logging changes

* add alert tests and reorganize a bit

* update arg options

* fix --exclude-actor-contains nargs

* more test fixes/updates

* fix alertstate choices in help

* remove "Accepts multiple args." from help messages

* enumerate rule types in help

* rename shared folder to search_shared

* rename shared folder to search_shared

* YYYY-MM-DD -> yyyy-MM-dd, along with clarity on partial time, and remove duplication of arg format message.

* move shared table init logic to base class

* adjust DateArgumentException error message to use max_days_back var instead of hardcoded #

* range compatibility

* get alert details instead of summaries in extraction

* update py42 minimum req

* update changelog

* implement clean interrupt handling

* remove test code

* docstring and changelog

* remove a test thing

* change decorator behavior to exit after function completes on first ctrl-c

Author: timabrmsn

CHANGELOG.md

@@ -47,6 +47,9 @@ how a consumer would use the library (e.g. adding unit tests, updating documenta
 - A custom error in the error log when you try adding unknown risk tags to user.
 
 - A custom error in the error log when you try adding a user to a detection list who is already added.
+- Graceful handling of keyboard interrupts (ctrl-c) so stack traces aren't printed to console.
+- Warning message printed when ctrl-c is encountered in the middle of an operation that could cause incorrect checkpoint
+    state, a second ctrl-c is required to quit while that operation is ongoing. 
 
 ### Fixed
 

src/code42cli/cmds/search_shared/extraction.py

@@ -7,6 +7,7 @@
 from code42cli.date_helper import parse_min_timestamp, parse_max_timestamp, verify_timestamp_order
 from code42cli.logger import get_main_cli_logger
 from code42cli.cmds.alerts.util import get_alert_details
+from code42cli.util import warn_interrupt
 
 logger = get_main_cli_logger()
 
@@ -50,6 +51,9 @@ def handle_error(exception):
         handlers.record_cursor_position = cursor_store.replace_stored_cursor_timestamp
         handlers.get_cursor_position = cursor_store.get_stored_cursor_timestamp
 
+    @warn_interrupt(
+        warning=u"Cancelling operation cleanly to keep checkpoint data accurate. One moment..."
+    )
     def handle_response(response):
         response_dict = json.loads(response.text)
         events = response_dict.get(event_key)

src/code42cli/main.py

@@ -1,4 +1,5 @@
 import platform
+import signal
 import sys
 
 from py42.settings import set_user_agent_suffix
@@ -15,6 +16,14 @@
 from code42cli.cmds.alerts.rules.commands import AlertRulesCommands
 
 
+# Handle KeyboardInterrupts by just exiting instead of printing out a stack
+def exit_on_interrupt(signal, frame):
+    sys.exit(1)
+
+
+signal.signal(signal.SIGINT, exit_on_interrupt)
+
+
 # If on Windows, configure console session to handle ANSI escape sequences correctly
 # source: https://bugs.python.org/issue29059
 if platform.system().lower() == u"windows":

src/code42cli/util.py

@@ -1,6 +1,8 @@
 from __future__ import print_function
 import sys
+from functools import wraps
 from os import makedirs, path
+from signal import signal, getsignal, SIGINT
 
 from code42cli.compat import open, str
 
@@ -88,3 +90,48 @@ def format_to_table(rows, column_size):
         for key in row.keys():
             print(str(row[key]).ljust(column_size[key] + _PADDING_SIZE), end=u" ")
         print(u"")
+
+
+class warn_interrupt(object):
+    """A context decorator class used to wrap functions where a keyboard interrupt could potentially
+    leave things in a bad state. Warns the user with provided message and exits when wrapped 
+    function is complete. Requires user to ctrl-c a second time to force exit.
+    
+    Usage:
+    
+    @warn_interrupt(warning="example message")
+    def my_important_func():
+        pass
+    """
+
+    def __init__(self, warning="Cancelling operation cleanly, one moment... "):
+        self.warning = warning
+        self.old_handler = None
+        self.interrupted = False
+        self.exit_instructions = "Hit CTRL-C again to force quit."
+
+    def __enter__(self):
+        self.old_handler = getsignal(SIGINT)
+        signal(SIGINT, self._handle_interrupts)
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if self.interrupted:
+            exit(1)
+        signal(SIGINT, self.old_handler)
+        return False
+
+    def _handle_interrupts(self, sig, frame):
+        if not self.interrupted:
+            self.interrupted = True
+            print("\n{}\n{}".format(self.warning, self.exit_instructions), file=sys.stderr)
+        else:
+            exit()
+
+    def __call__(self, func):
+        @wraps(func)
+        def inner(*args, **kwds):
+            with self:
+                return func(*args, **kwds)
+
+        return inner