fuzz_tests: refactor and add OSS-Fuzz compatibility

tests/fuzz/fuzzer.h

@@ -27,6 +27,52 @@
 // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <string>
+#include "file_io_utils.h"
+
+#ifdef OSSFUZZ
+
+#define BEGIN_INIT_SIMPLE_FUZZER() \
+  static int init() \
+  { \
+    try \
+    {
+
+#define END_INIT_SIMPLE_FUZZER() \
+    } \
+    catch (const std::exception &e) \
+    { \
+      fprintf(stderr, "Exception: %s\n", e.what()); \
+      return 1; \
+    } \
+    return 0; \
+  }
+
+#define BEGIN_SIMPLE_FUZZER() \
+extern "C" { \
+  int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) \
+  { \
+    try \
+    { \
+      static bool first = true; \
+      if (first) \
+      { \
+        if (!init()) \
+          return 1; \
+        first = false; \
+      } \
+
+#define END_SIMPLE_FUZZER() \
+    } \
+    catch (const std::exception &e) \
+    { \
+      fprintf(stderr, "Exception: %s\n", e.what()); \
+      return 1; \
+    } \
+    return 0; \
+  } \
+}
+
+#else
 
 class Fuzzer
 {
@@ -36,3 +82,57 @@ public:
 };
 
 int run_fuzzer(int argc, const char **argv, Fuzzer &fuzzer);
+
+#define BEGIN_INIT_SIMPLE_FUZZER() \
+  class SimpleFuzzer: public Fuzzer \
+  { \
+    virtual int init() \
+    { \
+      try \
+      {
+
+#define END_INIT_SIMPLE_FUZZER() \
+      } \
+      catch (const std::exception &e) \
+      { \
+        fprintf(stderr, "Exception: %s\n", e.what()); \
+        return 1; \
+      } \
+      return 0; \
+    }
+
+#define BEGIN_SIMPLE_FUZZER() \
+    virtual int run(const std::string &filename) \
+    { \
+      try \
+      { \
+        std::string s; \
+        if (!epee::file_io_utils::load_file_to_string(filename, s)) \
+        { \
+          std::cout << "Error: failed to load file " << filename << std::endl; \
+          return 1; \
+        } \
+        const uint8_t *buf = (const uint8_t*)s.data(); \
+        const size_t len = s.size(); \
+        {
+
+#define END_SIMPLE_FUZZER() \
+        } \
+      } \
+      catch (const std::exception &e) \
+      { \
+        fprintf(stderr, "Exception: %s\n", e.what()); \
+        return 1; \
+      } \
+      return 0; \
+    } \
+  }; \
+  int main(int argc, const char **argv) \
+  { \
+    TRY_ENTRY(); \
+    SimpleFuzzer fuzzer; \
+    return run_fuzzer(argc, argv, fuzzer); \
+    CATCH_ENTRY_L0("main", 1); \
+  }
+
+#endif