[protobuf-c] Restore missing fuzzer implementation

projects/protobuf-c/Dockerfile

@@ -28,5 +28,4 @@ RUN apt-get update && apt-get install -y \
 
 RUN git clone --depth 1 https://github.com/protobuf-c/protobuf-c.git -b next
 RUN git clone --depth 1 https://github.com/guidovranken/fuzzing-headers.git
-RUN git clone --depth 1 https://github.com/guidovranken/protobuf-c-fuzzers.git
-COPY build.sh $SRC/
+COPY build.sh fuzzer.cpp $SRC/

projects/protobuf-c/build.sh

@@ -47,8 +47,8 @@ make install
 cd $SRC/fuzzing-headers/
 ./install.sh
 
-cd $SRC/protobuf-c-fuzzers/
-cp $SRC/protobuf-c/t/test-full.proto $SRC/protobuf-c-fuzzers/
+cd $SRC
+cp $SRC/protobuf-c/t/test-full.proto $SRC/
 export PATH=$PATH:$SRC/protobuf-c/protoc-c
 protoc --c_out=. -I. -I/usr/local/include test-full.proto
 

projects/protobuf-c/fuzzer.cpp

@@ -0,0 +1,38 @@
+/* Copyright 2025 Google LLC
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+      http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/* Special thanks to Guido Vranken <guidovranken@gmail.com> */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <fuzzing/memory.hpp>
+#include "test-full.pb-c.h"
+
+#define X(OBJ, PREFIX) \
+    { \
+        OBJ* msg = PREFIX##__unpack(NULL, size, data); \
+        if ( msg != NULL ) { \
+            const size_t len = PREFIX##__get_packed_size(msg); \
+            uint8_t* copy = (uint8_t*)malloc(len); \
+            PREFIX##__pack(msg, copy); \
+            fuzzing::memory::memory_test(copy, len); \
+            free(copy); \
+        } \
+        PREFIX##__free_unpacked(msg, NULL); \
+    }
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+    X(Foo__TestMessSubMess, foo__test_mess_sub_mess);
+    X(Foo__TestFieldFlags, foo__test_field_flags);
+    X(Foo__TestMessageCheck, foo__test_message_check);
+    return 0;
+}