Test: Add a fuzzer for libmedia's metadata component

libmedia_metadata_fuzzer attempts to add random key/value pairs of the eligible types using metadata's appendBool and appendInt32 methods to a Metadata object. The fuzzer also calls the appendHeader() method to add a header, the updateLength() method during each iteration of appending key/val pairs and a resetParcel() method at the end.

Change-Id: I569c39954702f848bf5496528f7c3eb888c33ccc
diff --git a/media/libmedia/tests/fuzzer/Android.bp b/media/libmedia/tests/fuzzer/Android.bp
new file mode 100644
index 0000000..e58c396
--- /dev/null
+++ b/media/libmedia/tests/fuzzer/Android.bp
@@ -0,0 +1,10 @@
+cc_fuzz {
+  name: "libmedia_metadata_fuzzer",
+  srcs: [
+    "libmedia_metadata_fuzzer.cpp",
+  ],
+  shared_libs: [
+    "libmedia",
+    "libbinder",
+  ],
+}
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diff --git a/media/libmedia/tests/fuzzer/libmedia_metadata_fuzzer.cpp b/media/libmedia/tests/fuzzer/libmedia_metadata_fuzzer.cpp
new file mode 100644
index 0000000..058e4e5
--- /dev/null
+++ b/media/libmedia/tests/fuzzer/libmedia_metadata_fuzzer.cpp
@@ -0,0 +1,52 @@
+//This program fuzzes Metadata.cpp
+
+#include <stddef.h>
+#include <stdint.h>
+#include <fuzzer/FuzzedDataProvider.h>
+#include <media/Metadata.h>
+#include <binder/Parcel.h>
+
+using namespace android;
+using namespace media;
+
+static const float want_prob = 0.5;
+
+bool bytesRemain(FuzzedDataProvider *fdp);
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+    FuzzedDataProvider fdp(data, size);
+    Parcel p;
+    Metadata md = Metadata(&p);
+
+    md.appendHeader();
+    while (bytesRemain(&fdp)) {
+
+        float got_prob = fdp.ConsumeProbability<float>();
+        if (!bytesRemain(&fdp)) {
+            break;
+        }
+
+        if (got_prob < want_prob) {
+            int32_t key_bool = fdp.ConsumeIntegral<int32_t>();
+            if (!bytesRemain(&fdp)) {
+                break;
+            }
+            bool val_bool = fdp.ConsumeBool();
+            md.appendBool(key_bool, val_bool);
+        } else {
+            int32_t key_int32 = fdp.ConsumeIntegral<int32_t>();
+            if (!bytesRemain(&fdp)) {
+                break;
+            }
+            bool val_int32 = fdp.ConsumeIntegral<int32_t>();
+            md.appendInt32(key_int32, val_int32);
+        }
+        md.updateLength();
+    }
+    md.resetParcel();
+    return 0;
+}
+
+bool bytesRemain(FuzzedDataProvider *fdp){
+    return fdp -> remaining_bytes() > 0;
+}
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