webkitpy: Unify the exit status codes.

third_party/WebKit/Tools/Scripts/webkitpy/common/exit_codes.py

+# Copyright 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import signal
+
+OK_EXIT_STATUS = 0
+
+# This matches what the shell does on POSIX (returning -SIGNUM on unhandled
+# signal). (unsigned)(-SIGINT) == 128+signal.SIGINT
+INTERRUPTED_EXIT_STATUS = signal.SIGINT + 128
+
+# POSIX limits status codes to 0-255. Normally run-webkit-tests returns the
+# number of tests that failed. These indicate exceptional conditions triggered
+# by the script itself, so we count backwards from 255 (aka -1) to enumerate
+# them.
+#
+# FIXME: crbug.com/357866. We really shouldn't return the number of failures
+# in the exit code at all.
+EARLY_EXIT_STATUS = 251
+SYS_DEPS_EXIT_STATUS = 252
+NO_TESTS_EXIT_STATUS = 253
+NO_DEVICES_EXIT_STATUS = 254
+UNEXPECTED_ERROR_EXIT_STATUS = 255
+
+# FIXME: EXCEPTIONAL_EXIT_STATUS and NO_DEVICES_EXIT_STATUS conflict
+EXCEPTIONAL_EXIT_STATUS = 254
+
+ERROR_CODES = (
+    INTERRUPTED_EXIT_STATUS,
+    EARLY_EXIT_STATUS,
+    SYS_DEPS_EXIT_STATUS,
+    NO_TESTS_EXIT_STATUS,
+    NO_DEVICES_EXIT_STATUS,
+    UNEXPECTED_ERROR_EXIT_STATUS,
+)
+
+# In order to avoid colliding with the above codes, we put a ceiling on
+# the value returned by num_regressions
+MAX_FAILURES_EXIT_STATUS = 101