Add OrtGraphApis::OrtNode_GetAttributeStrWithSize to handle case wher…

…e attribute might contain null character (#22769)

When running EP Context model, EP might call
`OrtGraphApis::OrtNode_GetAttributeStr` to get the string-based content
of the attribute.
However, the API returns the c_str() of the string, and it's possible
that the cache context contains null character, so the string might be
cut off and caller ends up getting the wrong string.

Add a new OrtGraphApis::OrtNode_GetAttributeStrWithSize to return const
char* pointer and string size.

include/onnxruntime/core/session/onnxruntime_c_api_ep.h

@@ -556,6 +556,17 @@ ORT_API2_STATUS(OrtNode_GetAttributeIthFloat, const OrtNode* node, const char* k
  */
 ORT_API2_STATUS(OrtNode_GetAttributeIthStr, const OrtNode* node, const char* key, int i, _Outptr_ const char** out);
 
+/** \brief Gets the i-th string in the attribute with the given key.
+ *
+ * \param[in] node The node to query
+ * \param[in] key The attribute key
+ * \param[in] i The index of the string
+ * \param[out] out The i-th string in the attribute
+ * \param[out] size The length of the string
+ *
+ */
+ORT_API2_STATUS(OrtNode_GetAttributeIthStrWithSize, const OrtNode* node, const char* key, int i, _Outptr_ const char** out, _Outptr_ size_t* size);
+
 /** \brief Gets the string value of the attribute with the given key.
  *
  * \param[in] node The node to query
@@ -565,6 +576,16 @@ ORT_API2_STATUS(OrtNode_GetAttributeIthStr, const OrtNode* node, const char* key
  */
 ORT_API2_STATUS(OrtNode_GetAttributeStr, const OrtNode* node, const char* key, _Outptr_ const char** out);
 
+/** \brief Gets the string value of the attribute with the given key.
+ *
+ * \param[in] node The node to query
+ * \param[in] key The attribute key
+ * \param[out] out The string value of the attribute
+ * \param[out] size The length of the string 
+ *
+ */
+ORT_API2_STATUS(OrtNode_GetAttributeStrWithSize, const OrtNode* node, const char* key,  _Outptr_ const char** out, _Outptr_ size_t* size);
+
 /** \brief Gets the int value of the attribute with the given key.
  *
  * \param[in] node The node to query

onnxruntime/core/session/onnxruntime_c_api_ep.cc

@@ -752,12 +752,26 @@ ORT_API_STATUS_IMPL(OrtGraphApis::OrtNode_GetAttributeIthStr, const OrtNode* nod
   return nullptr;
 }
 
+ORT_API_STATUS_IMPL(OrtGraphApis::OrtNode_GetAttributeIthStrWithSize, const OrtNode* node, const char* key, int i, _Outptr_ const char** out, _Outptr_ size_t* size) {
+  const ::onnxruntime::Node* n = reinterpret_cast<const ::onnxruntime::Node*>(node);
+  *size = n->GetAttributes().at(key).strings(i).size();
+  *out = n->GetAttributes().at(key).strings(i).c_str();
+  return nullptr;
+}
+
 ORT_API_STATUS_IMPL(OrtGraphApis::OrtNode_GetAttributeStr, const OrtNode* node, const char* key, _Outptr_ const char** out) {
   const ::onnxruntime::Node* n = reinterpret_cast<const ::onnxruntime::Node*>(node);
   *out = n->GetAttributes().at(key).s().c_str();
   return nullptr;
 }
 
+ORT_API_STATUS_IMPL(OrtGraphApis::OrtNode_GetAttributeStrWithSize, const OrtNode* node, const char* key,  _Outptr_ const char** out, _Outptr_ size_t* size) {
+  const ::onnxruntime::Node* n = reinterpret_cast<const ::onnxruntime::Node*>(node);
+  *size = n->GetAttributes().at(key).s().size();
+  *out = n->GetAttributes().at(key).s().c_str();
+  return nullptr;
+}
+
 ORT_API_STATUS_IMPL(OrtGraphApis::OrtNode_GetAttributeInt, const OrtNode* node, const char* key, _Out_ int64_t* out) {
   const ::onnxruntime::Node* n = reinterpret_cast<const ::onnxruntime::Node*>(node);
   *out = n->GetAttributes().at(key).i();
@@ -841,7 +855,9 @@ static constexpr OrtGraphApi ort_graph_api = {
     &OrtGraphApis::OrtNode_GetAttributeIthInt,
     &OrtGraphApis::OrtNode_GetAttributeIthFloat,
     &OrtGraphApis::OrtNode_GetAttributeIthStr,
+    &OrtGraphApis::OrtNode_GetAttributeIthStrWithSize,
     &OrtGraphApis::OrtNode_GetAttributeStr,
+    &OrtGraphApis::OrtNode_GetAttributeStrWithSize,
     &OrtGraphApis::OrtNode_GetAttributeInt,
     &OrtGraphApis::OrtNode_GetAttributeFloat,
     &OrtGraphApis::OrtNode_GetSubgraphs,

onnxruntime/core/session/ort_apis_ep.h

@@ -105,8 +105,12 @@ ORT_API_STATUS_IMPL(OrtNode_GetAttributeIthFloat, const OrtNode* node, const cha
 
 ORT_API_STATUS_IMPL(OrtNode_GetAttributeIthStr, const OrtNode* node, const char* key, int i, _Outptr_ const char** out);
 
+ORT_API_STATUS_IMPL(OrtNode_GetAttributeIthStrWithSize, const OrtNode* node, const char* key, int i, _Outptr_ const char** out, _Outptr_ size_t* size);
+
 ORT_API_STATUS_IMPL(OrtNode_GetAttributeStr, const OrtNode* node, const char* key, _Outptr_ const char** out);
 
+ORT_API_STATUS_IMPL(OrtNode_GetAttributeStrWithSize, const OrtNode* node, const char* key, _Outptr_ const char** out, _Outptr_ size_t* size);
+
 ORT_API_STATUS_IMPL(OrtNode_GetAttributeInt, const OrtNode* node, const char* key, _Out_ int64_t* out);
 
 ORT_API_STATUS_IMPL(OrtNode_GetAttributeFloat, const OrtNode* node, const char* key, _Out_ float* out);

samples/tensorRTEp/onnx_ctx_model_helper.cc

@@ -127,8 +127,9 @@ OrtStatusPtr TensorRTCacheModelHandler::GetEpContextFromGraph(const OrtGraphView
   if (embed_mode) {
     // Get engine from byte stream.
     const char* context_binary_cstr = nullptr;
-    graph_api_->OrtNode_GetAttributeStr(node, EP_CACHE_CONTEXT.c_str(), &context_binary_cstr);
-    std::string context_binary(context_binary_cstr);
+    size_t size;
+    graph_api_->OrtNode_GetAttributeStr(node, EP_CACHE_CONTEXT.c_str(), &context_binary_cstr, &szie);
+    std::string context_binary(context_binary_cstr, size);
     *(trt_engine_) = std::unique_ptr<nvinfer1::ICudaEngine>(trt_runtime_->deserializeCudaEngine(const_cast<char*>(context_binary.c_str()),
                                                                                                 static_cast<size_t>(context_binary.length())));
 //    LOGS_DEFAULT(VERBOSE) << "[TensorRT EP] Read engine as binary data from \"ep_cache_context\" attribute of ep context node and deserialized it";