Import OEM build properties, if defined.

Certain products can define a list of system properties that should be
delegated to the OEM.  Since these properties may be ro.*, we give
them first shot at defining.

Also support blacklist of properties that should never be defined by
build.prop, used to delegate to runtime fingerprint generation.

Bug: 13367676
Change-Id: I3f00db732f485818205a7b76b31edbdc3a89aac0

tools/post_process_props.py

@@ -16,6 +16,9 @@
 
 import sys
 
+# Usage: post_process_props.py file.prop [blacklist_key, ...]
+# Blacklisted keys are removed from the property file, if present
+
 # See PROP_VALUE_MAX system_properties.h.
 # PROP_VALUE_MAX in system_properties.h includes the termination NUL,
 # so we decrease it by 1 here.
@@ -101,6 +104,10 @@ class PropFile:
         return
     self.lines.append(key + value)
 
+  def delete(self, name):
+    key = name + "="
+    self.lines = [ line for line in self.lines if not line.startswith(key) ]
+
   def write(self, f):
     f.write("\n".join(self.lines))
     f.write("\n")
@@ -124,6 +131,10 @@ def main(argv):
   if not validate(properties):
     sys.exit(1)
 
+  # Drop any blacklisted keys
+  for key in argv[2:]:
+    properties.delete(key)
+
   f = open(filename, 'w+')
   properties.write(f)
   f.close()