improved main function return handling

video2x/__main__.py

@@ -19,12 +19,15 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 Name: Package Main
 Author: K4YT3X
 Date Created: July 3, 2021
-Last Modified: February 11, 2022
+Last Modified: February 26, 2022
 """
 
 # local imports
 from .video2x import main
 
+# built-in imports
+import sys
+
 
 if __name__ == "__main__":
-    main()
+    sys.exit(main())

video2x/video2x.py

@@ -27,7 +27,7 @@ __      __  _       _                  ___   __   __
 Name: Video2X
 Creator: K4YT3X
 Date Created: February 24, 2018
-Last Modified: February 16, 2022
+Last Modified: February 27, 2022
 
 Editor: BrianPetkovsek
 Last Modified: June 17, 2019
@@ -491,21 +491,30 @@ def parse_arguments() -> argparse.Namespace:
     return parser.parse_args()
 
 
-def main() -> None:
+def main() -> int:
     """
-    command line direct invocation
-    program entry point
+    command line entrypoint for direct CLI invocation
+
+    :rtype int: 0 if completed successfully, else other int
     """
 
     try:
         # display version and lawful informaition
         if "--version" in sys.argv:
             print(LEGAL_INFO)
-            sys.exit(0)
+            return 0
 
         # parse command line arguments
         args = parse_arguments()
 
+        # check input/output file paths
+        if not args.input.exists():
+            logger.critical(f"Cannot find input file: {args.input}")
+            return 1
+        elif not args.input.is_file():
+            logger.critical(f"Input path is not a file")
+            return 1
+
         # set logger level
         if os.environ.get("LOGURU_LEVEL") is None:
             os.environ["LOGURU_LEVEL"] = args.loglevel.upper()
@@ -546,10 +555,12 @@ def main() -> None:
                 args.algorithm,
             )
 
+        return 0
+
     # don't print the traceback for manual terminations
     except KeyboardInterrupt as e:
-        raise SystemExit(e)
+        return 2
 
     except Exception as e:
         logger.exception(e)
-        raise SystemExit(e)
+        return 1