Add a script for enclosing interfaces in ifndef statements

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>

ifndefy.py

@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2021 Red Hat, Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library.  If not, see
+# <http://www.gnu.org/licenses/>.
+
+# About:
+# When provided with an interface file, this script outputs a new interface
+# file, where all original interfaces are enclosed in an ifndef statement
+# dependent on their name. All indentation inside the interface file should
+# be converted to tabs before running this script.
+# 
+# Known issues:
+# - interface already enclosed in an ifndef statement is not ignored
+# - "`"  and "'" inside comments are not ignored
+# - \t is always used for indentation - may result in mixture of spaces and tabs
+
+import sys
+import os
+import re
+
+if len(sys.argv) < 1:
+    print(("Usage: {} <policy>.if > <output>.if").format(sys.argv[0]), file=sys.stderr)
+    exit(os.EX_USAGE)
+
+# ending index of interface
+end = 0
+with open(sys.argv[1], 'r') as f:
+    interfaces = f.read()
+    file_len = len(interfaces)
+
+    while end < file_len:
+        start = interfaces.find("interface(`", end)
+        if start < 0:
+            #no more interfaces
+            print(interfaces[end:], end ="")
+            break
+        name_end = interfaces.find("'", start+11)
+        name = interfaces[start+11:name_end]
+
+        # locate the end of the interface - i.e. ending apostrophe
+        reg = re.compile(r"[`']")
+        # skip the ' after interface name
+        i = name_end+1
+        # counter for the depth (` opens a new block, while ' closes it)
+        graves = 0
+        while i < file_len:
+            match = reg.search(interfaces, i)
+            if not match:
+                print("Malformed interface: {}".format(name), file=sys.stderr)
+                exit(1)
+
+            i = match.end()
+            if match.group(0) == '`':
+                graves += 1
+            else:
+                graves -= 1
+                if graves == 0:
+                    break
+
+        # keep everything between the end of previous interface and start of a new one
+        print(interfaces[end:start], end ="")
+        # interface ends in "')" -- add 1 for the edning bracket
+        end = i+1
+        # print the whole interface enclosed in "ifndef"
+        print("ifndef(`{}',`".format(name))
+        print('\n'.join([('\t' + x) if x else x for x in interfaces[start:end].split('\n')]))
+        print("')", end ="")