A build property's value is returned empty in runtime when its length

exceeds 92 symbols (91 valid symbols + \0). It is better to catch that
issue on earlier stage, i.e. fail the build with an appropriate message.

For developer's build, show warning message instead of failing the build
(in the latter case, as developers do not usually care about build properties
too much).

Change-Id: I03ced7b486d43a71b1921e0a9c48b43aa30727c7

tools/post_process_props.py

@@ -19,7 +19,27 @@ import sys
 # Put the modifications that you need to make into the /system/build.prop into this
 # function. The prop object has get(name) and put(name,value) methods.
 def mangle_build_prop(prop):
-  pass
+  buildprops=prop.buildprops
+  check_pass=True
+  for key in buildprops:
+    # Check build properties' length.
+    # Terminator(\0) added into the provided value of properties
+    # Total length (including terminator) will be no greater that PROP_VALUE_MAX(92).
+    if len(buildprops[key]) > 91:
+      # If dev build, show a warning message, otherwise fail the build with error message
+      if prop.get("ro.build.version.incremental").startswith("eng"):
+        sys.stderr.write("warning: " + key + " exceeds 91 symbols: ")
+        sys.stderr.write(buildprops[key])
+        sys.stderr.write("(" + str(len(buildprops[key])) + ") \n")
+        sys.stderr.write("warning: This will cause the " + key + " ")
+        sys.stderr.write("property return as empty at runtime\n")
+      else:
+        check_pass=False
+        sys.stderr.write("error: " + key + " cannot exceed 91 symbols: ")
+        sys.stderr.write(buildprops[key])
+        sys.stderr.write("(" + str(len(buildprops[key])) + ") \n")
+  if not check_pass:
+    sys.exit(1)
 
 # Put the modifications that you need to make into the /system/build.prop into this
 # function. The prop object has get(name) and put(name,value) methods.
@@ -40,8 +60,19 @@ def mangle_default_prop(prop):
     prop.put("persist.sys.usb.config", "none");
 
 class PropFile:
+
+  buildprops={}
+
   def __init__(self, lines):
     self.lines = [s[:-1] for s in lines]
+    for line in self.lines:
+      line=line.strip()
+      if not line.strip() or line.startswith("#"):
+        continue
+      index=line.find("=")
+      key=line[0:index]
+      value=line[index+1:]
+      self.buildprops[key]=value
 
   def get(self, name):
     key = name + "="