1 files changed, 84 insertions, 0 deletions
diff --git a/merge.py b/merge.py
new file mode 100755
index 000000000..e1d0efdae
--- /dev/null
+++ b/merge.py
@@ -0,0 +1,84 @@
+#!/usr/bin/python3
+# SPDX-License-Identifier: GPL-2.0
+# Author: Clark Williams <williams@redhat.com>
+# Copyright (C) 2022 Red Hat, Inc.
+#
+# merge.py - a direct replacement for merge.pl in the redhat/configs directory
+#
+# invocation:   python merge.py overrides baseconfig [arch]
+#
+# This script merges two kernel configuration files, an override file and a
+# base config file and writes the results to stdout.
+#
+# The script reads the overrides into a dictionary, then reads the baseconfig
+# file, looking for overrides and replacing any found, then printing the result
+# to stdout. Finally any remaining (new) configs in the override are appended to the
+# end of the output
+
+import sys
+import re
+import os.path
+
+def usage(msg):
+    '''print a usage message and exit'''
+    sys.stderr.write(msg + "\n")
+    sys.stderr.write("usage: merge.py overrides baseconfig [arch]\n")
+    sys.exit(1)
+
+isset = re.compile(r'^(CONFIG_\w+)=')
+notset = re.compile(r'^#\s+(CONFIG_\w+)\s+is not set')
+
+# search an input line for a config (set or notset) pattern
+# if we get a match return the config that is being changed
+def find_config(line):
+    '''find a configuration line in the input and return the config name'''
+    if m := isset.match(line):
+        return m.group(1)
+    if m := notset.match(line):
+        return m.group(1)
+    return None
+
+#########################################################
+
+if len(sys.argv) < 3:
+    usage("must have two input files")
+
+override_file = sys.argv[1]
+baseconfig_file = sys.argv[2]
+
+if not os.path.exists(override_file):
+    usage(f"overrides config file {override_file: s} does not exist!")
+
+if not os.path.exists(baseconfig_file):
+    usage(f"base configs file {baseconfig_file: s} does not exist")
+
+if len(sys.argv) == 4:
+    print(f"# {sys.argv[3]:s}")
+
+# read each line of the override file and store any configuration values
+# in the overrides dictionary, keyed by the configuration name.
+overrides = {}
+with open(override_file, "rt", encoding="utf-8") as f:
+    for line in [l.strip() for l in f.readlines()]:
+        c = find_config(line)
+        if c and c not in overrides:
+            overrides[c] = line
+
+# now read and print the base config, checking each line
+# that defines a config value and printing the override if
+# it exists
+with open(baseconfig_file, "rt", encoding="utf-8") as f:
+    for line in [ l.strip() for l in f.readlines() ]:
+        c = find_config(line)
+        if c and c in overrides:
+            print(overrides[c])
+            del overrides[c]
+        else:
+            print(line)
+
+# print out the remaining configs (new values)
+# from the overrides file
+for v in overrides.values():
+    print (v)
+
+sys.exit(0)