Added GetAvailableProviders() to C API (#4247)

* Added GetAvailableProviders to C API

* Fix API version and Windows build error

* Changed function name

* Changed ORT_API_VERSION to 4

* Moved all_providers array to constants.h

* Move check for providers to constants.h

* Changed name of array to avoid warning

* Address review comment

* Added unit test

include/onnxruntime/core/graph/constants.h

@@ -38,4 +38,46 @@ constexpr const char* kDmlExecutionProvider = "DmlExecutionProvider";
 constexpr const char* kMIGraphXExecutionProvider = "MIGraphXExecutionProvider";
 constexpr const char* kAclExecutionProvider = "ACLExecutionProvider";
 constexpr const char* kArmNNExecutionProvider = "ArmNNExecutionProvider";
+constexpr const char *providers_available[] = {
+  kCpuExecutionProvider,
+#ifdef USE_CUDA
+  kCudaExecutionProvider,
+#endif
+#ifdef USE_DNNL
+  kDnnlExecutionProvider,
+#endif
+#ifdef USE_NGRAPH
+  kNGraphExecutionProvider,
+#endif
+#ifdef USE_OPENVINO
+  kOpenVINOExecutionProvider,
+#endif
+#ifdef USE_NUPHAR
+  kNupharExecutionProvider,
+#endif
+#ifdef USE_VITISAI
+  kVitisAIExecutionProvider,
+#endif
+#ifdef USE_TENSORRT
+  kTensorrtExecutionProvider,
+#endif
+#ifdef USE_NNAPI
+  kNnapiExecutionProvider,
+#endif
+#ifdef USE_RKNPU
+  kRknpuExecutionProvider,
+#endif
+#ifdef USE_DML
+  kDmlExecutionProvider,
+#endif
+#ifdef USE_MIGRAPHX
+  kMIGraphXExecutionProvider,
+#endif
+#ifdef USE_ACL
+  kAclExecutionProvider,
+#endif
+#ifdef USE_ARMNN
+  kArmNNExecutionProvider,
+#endif
+};
 }  // namespace onnxruntime

include/onnxruntime/core/session/onnxruntime_c_api.h

@@ -7,7 +7,7 @@
 #include <string.h>
 
 // This value is used in structures passed to ORT so that a newer version of ORT will still work with them
-#define ORT_API_VERSION 3
+#define ORT_API_VERSION 4
 
 #ifdef __cplusplus
 extern "C" {
@@ -817,6 +817,25 @@ struct OrtApi {
   ORT_API2_STATUS(AddFreeDimensionOverrideByName,
                   _Inout_ OrtSessionOptions* options, _In_ const char* dim_name,
                   _In_ int64_t dim_value);
+
+  /**
+   * \param out_ptr will hold a pointer to the array of char *
+   * representing available providers.
+   * \param provider_length is a pointer to an int variable where
+   * the number of available providers will be added.
+   * The caller is responsible for freeing each char * and the pointer
+   * array by calling ReleaseAvailableProviders().
+   */
+  ORT_API2_STATUS(GetAvailableProviders, _Outptr_ char ***out_ptr,
+                  _In_ int *provider_length);
+
+  /**
+   * \param ptr is the pointer to an array of available providers you
+   * get after calling GetAvailableProviders().
+   * \param providers_length is the number of available providers.
+   */
+  ORT_API2_STATUS(ReleaseAvailableProviders, _In_ char **ptr,
+                  _In_ int providers_length);
 };
 
 /*

onnxruntime/core/session/onnxruntime_c_api.cc

@@ -14,6 +14,7 @@
 #include "core/common/logging/logging.h"
 #include "core/common/status.h"
 #include "core/common/safeint.h"
+#include "core/graph/constants.h"
 #include "core/graph/graph.h"
 #include "core/framework/allocator.h"
 #include "core/framework/tensor.h"
@@ -981,7 +982,7 @@ ORT_STATUS_PTR OrtGetValueImplSeqOfTensors(_In_ const OrtValue* p_ml_value, int
   return t_disp.template InvokeWithUnsupportedPolicy<UnsupportedReturnFailStatus>(allocator, one_tensor, out);
 }
 
-#ifdef _MSVC_VER
+#ifdef _MSC_VER
 #pragma warning(pop)
 #endif
 
@@ -1375,6 +1376,46 @@ ORT_API_STATUS_IMPL(OrtApis::GetOpaqueValue, _In_ const char* domain_name, _In_
   return nullptr;
 }
 
+ORT_API_STATUS_IMPL(OrtApis::GetAvailableProviders, _Outptr_ char ***out_ptr,
+                    _In_ int *providers_length) {
+  API_IMPL_BEGIN
+  const size_t MAX_LEN = 30;
+  int available_count = (int)(sizeof(providers_available) / sizeof(char *));
+  char **out = (char **)malloc(available_count * sizeof(char *));
+  if(out) {
+    for(int i = 0; i < available_count; i++) {
+      out[i] = (char *)malloc((MAX_LEN + 1) * sizeof(char));
+      if(out[i]) {
+#ifdef _MSC_VER
+        strncpy_s(out[i], MAX_LEN, providers_available[i], MAX_LEN);
+#else
+        strncpy(out[i], providers_available[i], MAX_LEN);
+#endif
+        out[i][MAX_LEN] = '\0';
+      }
+    }
+  }
+  *providers_length = available_count;
+  *out_ptr = out;
+  API_IMPL_END
+  return NULL;
+}
+
+ORT_API_STATUS_IMPL(OrtApis::ReleaseAvailableProviders, _In_ char **ptr,
+                    _In_ int providers_length) {
+  API_IMPL_BEGIN
+  if(ptr) {
+    for(int i = 0; i < providers_length; i++) {
+      if(ptr[i]) {
+        free(ptr[i]);
+      }
+    }
+    free(ptr);
+  }
+  API_IMPL_END
+  return NULL;
+}
+
 // End support for non-tensor types
 
 static constexpr OrtApiBase ort_api_base = {
@@ -1421,7 +1462,7 @@ Second example, if we wanted to add and remove some members, we'd do this:
 	In GetApi we now make it return ort_api_3 for version 3.
 */
 
-static constexpr OrtApi ort_api_1_to_3 = {
+static constexpr OrtApi ort_api_1_to_4 = {
     // NOTE: The ordering of these fields MUST not change after that version has shipped since existing binaries depend on this ordering.
 
     // Shipped as version 1 - DO NOT MODIFY (see above text for more information)
@@ -1560,21 +1601,26 @@ static constexpr OrtApi ort_api_1_to_3 = {
     &OrtApis::ReleaseModelMetadata,
     // End of Version 2 - DO NOT MODIFY ABOVE (see above text for more information)
 
-    // Version 3 - In development, feel free to add/remove/rearrange here
     &OrtApis::CreateEnvWithGlobalThreadPools,
     &OrtApis::DisablePerSessionThreads,
     &OrtApis::CreateThreadingOptions,
     &OrtApis::ReleaseThreadingOptions,
     &OrtApis::ModelMetadataGetCustomMetadataMapKeys,
-    &OrtApis::AddFreeDimensionOverrideByName};
+    &OrtApis::AddFreeDimensionOverrideByName,
+    // End of Version 3 - DO NOT MODIFY ABOVE (see above text for more information)
+
+    // Version 4 - In development, feel free to add/remove/rearrange here
+    &OrtApis::GetAvailableProviders,
+    &OrtApis::ReleaseAvailableProviders,
+};
 
 // Assert to do a limited check to ensure Version 1 of OrtApi never changes (will detect an addition or deletion but not if they cancel out each other)
 // If this assert hits, read the above 'Rules on how to add a new Ort API version'
 static_assert(offsetof(OrtApi, ReleaseCustomOpDomain) / sizeof(void*) == 101, "Size of version 1 API cannot change");
 
 ORT_API(const OrtApi*, OrtApis::GetApi, uint32_t version) {
-  if (version >= 1 && version <= 3)
-    return &ort_api_1_to_3;
+  if (version >= 1 && version <= 4)
+    return &ort_api_1_to_4;
 
   return nullptr;  // Unsupported version
 }

onnxruntime/core/session/ort_apis.h

@@ -198,4 +198,8 @@ ORT_API_STATUS_IMPL(ModelMetadataGetCustomMetadataMapKeys, _In_ const OrtModelMe
 
 ORT_API_STATUS_IMPL(AddFreeDimensionOverrideByName, _Inout_ OrtSessionOptions* options, _In_ const char* dim_name, _In_ int64_t dim_value);
 
+ORT_API_STATUS_IMPL(GetAvailableProviders, _Outptr_ char ***out_ptr,
+                    _In_ int *providers_length);
+ORT_API_STATUS_IMPL(ReleaseAvailableProviders, _In_ char **ptr,
+                    _In_ int providers_length);
 }  // namespace OrtApis

onnxruntime/test/shared_lib/test_inference.cc

@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 #include <core/common/make_unique.h>
+#include "core/session/onnxruntime_c_api.h"
 #include "core/session/onnxruntime_cxx_api.h"
 #include "core/graph/constants.h"
 #include "providers.h"
@@ -581,3 +582,13 @@ TEST(CApiTest, model_metadata) {
     ASSERT_TRUE(custom_metadata_map_keys == nullptr);
   }
 }
+
+TEST(CApiTest, get_available_providers) {
+  const OrtApi *g_ort = OrtGetApiBase()->GetApi(ORT_API_VERSION);
+  int len = 0;
+  char **providers;
+  ASSERT_EQ(g_ort->GetAvailableProviders(&providers, &len), nullptr);
+  ASSERT_TRUE(len > 0);
+  ASSERT_EQ(strcmp(providers[0], "CPUExecutionProvider"), 0);
+  ASSERT_EQ(g_ort->ReleaseAvailableProviders(providers, len), nullptr);
+}