Ryanunderhill/c api string arg

include/onnxruntime/core/session/onnxruntime_c_api.h

@@ -548,6 +548,7 @@ struct OrtCustomOpApi {
   */
   OrtStatus*(ORT_API_CALL* KernelInfoGetAttribute_float)(_In_ const OrtKernelInfo* info, _In_ const char* name, _Out_ float* out);
   OrtStatus*(ORT_API_CALL* KernelInfoGetAttribute_int64)(_In_ const OrtKernelInfo* info, _In_ const char* name, _Out_ int64_t* out);
+  OrtStatus*(ORT_API_CALL* KernelInfoGetAttribute_string)(_In_ const OrtKernelInfo* info, _In_ const char* name, _Out_ char* out, _Inout_ size_t* size);
 
   OrtStatus*(ORT_API_CALL* GetTensorTypeAndShape)(_In_ const OrtValue* value, _Out_ OrtTensorTypeAndShapeInfo** out);
 

include/onnxruntime/core/session/onnxruntime_cxx_api.h

@@ -252,7 +252,7 @@ struct AllocatorInfo : Base<OrtAllocatorInfo> {
 struct CustomOpApi {
   CustomOpApi(const OrtCustomOpApi& api) : api_(api) {}
 
-  template <typename T>  // T is only implemented for float and int64_t
+  template <typename T>  // T is only implemented for float, int64_t, and string
   T KernelInfoGetAttribute(_In_ const OrtKernelInfo* info, _In_ const char* name);
 
   OrtTensorTypeAndShapeInfo* GetTensorTypeAndShape(_In_ const OrtValue* value);

include/onnxruntime/core/session/onnxruntime_cxx_inline.h

@@ -393,6 +393,24 @@ inline int64_t CustomOpApi::KernelInfoGetAttribute<int64_t>(_In_ const OrtKernel
   return out;
 }
 
+template <>
+inline std::string CustomOpApi::KernelInfoGetAttribute<std::string>(_In_ const OrtKernelInfo* info, _In_ const char* name) {
+  size_t size = 0;
+  std::string out;
+  OrtStatus* status = api_.KernelInfoGetAttribute_string(info, name, nullptr, &size);
+
+  // The status should be ORT_INVALID_ARGUMENT because the size is insufficient to hold the string
+  if (OrtGetErrorCode(status) == ORT_INVALID_ARGUMENT) {
+    OrtReleaseStatus(status);
+    out.resize(size);
+    ORT_THROW_ON_ERROR(api_.KernelInfoGetAttribute_string(info, name, &out[0], &size));
+    out.resize(size - 1); // remove the terminating character '\0'
+  } else {
+    ORT_THROW_ON_ERROR(status);
+  }
+  return out;
+}
+
 inline OrtTensorTypeAndShapeInfo* CustomOpApi::GetTensorTypeAndShape(_In_ const OrtValue* value) {
   OrtTensorTypeAndShapeInfo* out;
   ORT_THROW_ON_ERROR(api_.GetTensorTypeAndShape(value, &out));

onnxruntime/core/session/custom_ops.cc

@@ -50,9 +50,27 @@ ORT_API_STATUS_IMPL(OrtKernelContext_GetOutput, OrtKernelContext* context, _In_
   return nullptr;
 };
 
+ORT_API_STATUS_IMPL(OrtKernelInfoGetAttribute_string, _In_ const OrtKernelInfo* info, _In_ const char* name, _Out_ char* out, _Inout_ size_t *size) {
+  std::string value;
+  auto status = reinterpret_cast<const onnxruntime::OpKernelInfo*>(info)->GetAttr<std::string>(name, &value);
+  if (status.IsOK()) {
+    if (*size >= value.size() + 1) {
+      std::memcpy(out, value.data(), value.size());
+      out[value.size()] = '\0';
+      *size = value.size();
+      return nullptr;
+    } else {
+      *size = value.size() + 1;
+      return OrtCreateStatus(ORT_INVALID_ARGUMENT, "Result buffer is not large enough");
+    }
+  }
+  return onnxruntime::ToOrtStatus(status);
+}
+
 constexpr OrtCustomOpApi g_custom_op_api = {
     &OrtKernelInfoGetAttribute_float,
     &OrtKernelInfoGetAttribute_int64,
+    &OrtKernelInfoGetAttribute_string,
 
     &OrtGetTensorTypeAndShape,
 

onnxruntime/core/session/inference_session.cc

@@ -11,6 +11,7 @@
 #include <sstream>
 #include <unordered_set>
 #include <list>
+#include <string>
 #include <thread>
 
 #include "core/common/logging/logging.h"