Add grammar section to libfuzzer options file.

Change-Id: I7b9300b0260cc734d955a59c11df8551fbfb1d04
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2080865
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Reviewed-by: Martin Barbella <mbarbella@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749241}

testing/libfuzzer/fuzzer_test.gni

@@ -24,6 +24,7 @@ import("//testing/test.gni")
 # - ubsan_options - UndefinedBehaviorSanitizer options.
 # - seed_corpus - a directory with seed corpus.
 # - seed_corpus_deps - dependencies for generating the seed corpus.
+# - grammar - defines a grammar used by a grammar based mutator.
 #
 # If use_libfuzzer gn flag is defined, then proper fuzzer would be build.
 # Without use_libfuzzer or use_afl a unit-test style binary would be built on
@@ -90,7 +91,7 @@ template("fuzzer_test") {
     if (defined(invoker.dict) || defined(invoker.libfuzzer_options) ||
         defined(invoker.asan_options) || defined(invoker.msan_options) ||
         defined(invoker.ubsan_options) ||
-        defined(invoker.environment_variables)) {
+        defined(invoker.environment_variables) || defined(invoker.grammar)) {
       if (defined(invoker.dict)) {
         # Copy dictionary to output.
         copy(target_name + "_dict_copy") {
@@ -142,6 +143,11 @@ template("fuzzer_test") {
           args += invoker.environment_variables
         }
 
+        if (defined(invoker.grammar)) {
+          args += [ "--grammar" ]
+          args += invoker.grammar
+        }
+
         outputs = [ "$root_build_dir/$config_file_name" ]
       }
       test_deps += [ ":" + config_file_name ]

testing/libfuzzer/gen_fuzzer_config.py

@@ -40,6 +40,7 @@ def main():
   parser.add_argument('--asan_options', nargs='+', default=[])
   parser.add_argument('--msan_options', nargs='+', default=[])
   parser.add_argument('--ubsan_options', nargs='+', default=[])
+  parser.add_argument('--grammar', nargs='+', default=[])
   parser.add_argument(
       '--environment_variables',
       nargs='+',
@@ -49,7 +50,8 @@ def main():
 
   # Script shouldn't be invoked without any arguments, but just in case.
   if not (args.dict or args.libfuzzer_options or args.environment_variables or
-          args.asan_options or args.msan_options or args.ubsan_options):
+          args.asan_options or args.msan_options or args.ubsan_options or
+          args.grammar):
     return
 
   config = ConfigParser.ConfigParser()
@@ -70,6 +72,9 @@ def main():
   AddSectionOptions(config, 'ubsan',
                     [option.split('=') for option in args.ubsan_options])
 
+  AddSectionOptions(config, 'grammar',
+                    [option.split('=') for option in args.grammar])
+
   AddSectionOptions(
       config, 'env',
       [option.split('=') for option in args.environment_variables])