Improved exception handling for symlink operations

Author: magnolialogic

transcode.py

@@ -100,21 +100,32 @@ def link():
 		proceed = get_user_response()
 		if proceed:
 			if not oct(os.stat(script_realpath).st_mode)[-3:] == 755:
-				os.chmod(script_realpath, 0o755)
+				try:
+					os.chmod(script_realpath, 0o755)
+				except PermissionError:
+					sys.exit("\nError: failed to make {script_name} executable, operation not permitted.".format(script_name=script_name))
 			print("Use default location? /usr/local/bin")
 			default_location = get_user_response()
 			if default_location:
-				os.symlink(script_realpath, os.path.join("usr", "local", "bin", script_name))
-				sys.exit("Created symlink to {script_name} in /usr/local/bin\n")
+				try:
+					os.symlink(script_realpath, os.path.join(os.sep, "usr", "local", "bin", script_name))
+				except PermissionError:
+					sys.exit("\nError: failed to create symlink, operation not permitted.")
+				else:
+					sys.exit("Created symlink to {script_name} in /usr/local/bin\n")
 			else:
 				print("Use alternate $PATH location?")
 				alternate_location = get_user_response()
 				if alternate_location:
 					alternate_path = str(input("Alternate $PATH location: (case-sensitive) "))
 					if alternate_path[0] == "~": alternate_path = os.path.expanduser(alternate_path)
 					if alternate_path in os.get_exec_path():
-						os.symlink(script_realpath, os.path.join(alternate_path, script_name))
-						sys.exit("Created symlink to {script_name} in {alternate_path}\n".format(script_name=script_name, alternate_path=alternate_path))
+						try:
+							os.symlink(script_realpath, os.path.join(alternate_path, script_name))
+						except PermissionError:
+							sys.exit("\nError: failed to create symlink, operation not permitted.")
+						else:
+							sys.exit("Created symlink to {script_name} in {alternate_path}\n".format(script_name=script_name, alternate_path=alternate_path))
 					else:
 						sys.exit("\nError: {alternate_path} not found on $PATH, aborting install.\n".format(alternate_path=alternate_path))
 				else:
@@ -128,8 +139,12 @@ def unlink():
 			print("Remove symlink to {script_name} in {path_dir}?".format(script_name=script_name, path_dir=path_dir))
 			proceed = get_user_response()
 			if proceed:
-				os.unlink(script_path_location)
-				print("Unlinked {script_path_location}\n".format(script_path_location=script_path_location))
+				try:
+					os.unlink(script_path_location)
+				except PermissionError:
+					sys.exit("\nError: operation not permitted.")
+				else:
+					print("Unlinked {script_path_location}\n".format(script_path_location=script_path_location))
 			else:
 				sys.exit("Aborting uninstall.\n")
 		else: