core decompress example: add fuzzer test code

Author: Grok Compression

examples/core/core_decompress.cpp

@@ -577,6 +577,87 @@ int main([[maybe_unused]] int argc, [[maybe_unused]] const char** argv)
     return app.exit(e); // Handle parsing errors
   }
 
+// #define TEST_FUZZER
+#ifdef TEST_FUZZER
+  {
+    grk_header_info headerInfo = {};
+    grk_decompress_parameters parameters = {};
+    parameters.dw_x1 = 1024;
+    parameters.dw_y1 = 1024;
+    grk_object* codec = nullptr;
+    grk_stream_params stream_params = {};
+    size_t len = 0;
+    uint8_t* buf = nullptr;
+    FILE* file = nullptr;
+
+    auto cleanup = [&]() {
+      if(buf)
+        free(buf);
+      if(codec)
+        grk_object_unref(codec);
+      if(file)
+        fclose(file);
+    };
+
+    // Open the file
+    file = fopen(inputFilePath.c_str(), "rb");
+    if(!file)
+    {
+      fprintf(stderr, "Failed to open file: %s\n", inputFilePath.c_str());
+      cleanup();
+      return -1;
+    }
+
+    // Get file size
+    fseek(file, 0, SEEK_END);
+    len = (size_t)ftell(file);
+    fseek(file, 0, SEEK_SET);
+
+    // Allocate buffer
+    buf = (uint8_t*)malloc(len);
+    if(!buf)
+    {
+      fprintf(stderr, "Failed to allocate buffer for file\n");
+      cleanup();
+      return -1;
+    }
+
+    // Read file into buffer
+    size_t bytesRead = fread(buf, 1, len, file);
+    if(bytesRead != len)
+    {
+      fprintf(stderr, "Failed to read file: %s\n", inputFilePath.c_str());
+      cleanup();
+      return -1;
+    }
+
+    // Close the file
+    fclose(file);
+
+    // Set stream parameters
+    stream_params.buf = buf;
+    stream_params.buf_len = len;
+
+    // Proceed with decompression
+    codec = grk_decompress_init(&stream_params, &parameters);
+    if(!codec)
+    {
+      cleanup();
+      return -1;
+    }
+    if(!grk_decompress_read_header(codec, &headerInfo))
+    {
+      cleanup();
+      return -1;
+    }
+    if(!grk_decompress(codec, nullptr))
+    {
+      cleanup();
+      return -1;
+    }
+  }
+#endif
+
   // initialize decompress parameters
   grk_decompress_parameters decompressParams = {};
   decompressParams.core.skip_allocate_composite = !doStore;