Add return code functions (borgbackup#2199)

src/borg/archiver.py

@@ -36,7 +36,7 @@
 from .constants import *  # NOQA
 from .crc32 import crc32
 from .helpers import EXIT_SUCCESS, EXIT_WARNING, EXIT_ERROR
-from .helpers import Error, NoManifestError
+from .helpers import Error, NoManifestError, set_ec
 from .helpers import location_validator, archivename_validator, ChunkerParams, CompressionSpec
 from .helpers import PrefixSpec, SortBySpec, HUMAN_SORT_KEYS
 from .helpers import BaseFormatter, ItemFormatter, ArchiveFormatter
@@ -3372,7 +3372,7 @@ def run(self, args):
         self.prerun_checks(logger)
         if is_slow_msgpack():
             logger.warning("Using a pure-python msgpack! This will result in lower performance.")
-        return func(args)
+        return set_ec(func(args))
 
 
 def sig_info_handler(sig_no, stack):  # pragma: no cover

src/borg/helpers.py

@@ -52,6 +52,26 @@ def Chunk(data, **meta):
     return _Chunk(meta, data)
 
 
+'''
+The global exit_code variable is used so that modules other than archiver can increase the program exit code if a
+warning or error occured during their operation. This is different from archiver.exit_code, which is only accessible
+from the archiver object.
+'''
+exit_code = EXIT_SUCCESS
+
+
+def set_ec(ec):
+    '''
+    Sets the exit code of the program, if an exit code higher or equal than this is set, this does nothing. This
+    makes EXIT_ERROR override EXIT_WARNING, etc..
+
+    ec: exit code to set
+    '''
+    global exit_code
+    exit_code = max(exit_code, ec)
+    return exit_code
+
+
 class Error(Exception):
     """Error base class"""
 

src/borg/testsuite/archiver.py

@@ -79,6 +79,7 @@ def exec_cmd(*args, archiver=None, fork=False, exe=None, **kw):
                 archiver = Archiver()
             archiver.prerun_checks = lambda *args: None
             archiver.exit_code = EXIT_SUCCESS
+            helpers.exit_code = EXIT_SUCCESS
             try:
                 args = archiver.parse_args(list(args))
                 # argparse parsing may raise SystemExit when the command line is bad or