Allow TF_Delete* functions to accept nullptr

The TF_Delete* functions in TensorFlow's C API now safely do nothing when asked to delete a null pointer. This mirrors the behaviour of free in C and delete in C++.

PiperOrigin-RevId: 205844191

3 files changed, 29 insertions, 0 deletions

diff --git a/tensorflow/c/c_api.cc b/tensorflow/c/c_api.cc
index 1b937883c8..f516ce4f18 100644
--- a/tensorflow/c/c_api.cc
+++ b/tensorflow/c/c_api.cc
@@ -328,6 +328,7 @@ TF_Buffer* TF_NewBufferFromString(const void* proto, size_t proto_len) {
 }
 
 void TF_DeleteBuffer(TF_Buffer* buffer) {
+  if (buffer == nullptr) return;
   if (buffer->data_deallocator != nullptr) {
     (*buffer->data_deallocator)(const_cast<void*>(buffer->data),
                                 buffer->length);
@@ -357,6 +358,7 @@ void TF_CloseDeprecatedSession(TF_DeprecatedSession* s, TF_Status* status) {
 
 void TF_DeleteDeprecatedSession(TF_DeprecatedSession* s, TF_Status* status) {
   status->status = Status::OK();
+  if (s == nullptr) return;
   delete s->session;
   delete s;
 }
@@ -907,6 +909,7 @@ TF_Library* TF_LoadLibrary(const char* library_filename, TF_Status* status) {
 TF_Buffer TF_GetOpList(TF_Library* lib_handle) { return lib_handle->op_list; }
 
 void TF_DeleteLibraryHandle(TF_Library* lib_handle) {
+  if (lib_handle == nullptr) return;
   tensorflow::port::Free(const_cast<void*>(lib_handle->op_list.data));
   delete lib_handle;
 }
@@ -1854,6 +1857,7 @@ TF_Graph::TF_Graph()
 TF_Graph* TF_NewGraph() { return new TF_Graph; }
 
 void TF_DeleteGraph(TF_Graph* g) {
+  if (g == nullptr) return;
   g->mu.lock();
   g->delete_requested = true;
   const bool del = g->sessions.empty();
@@ -2529,6 +2533,7 @@ void TF_CloseSession(TF_Session* s, TF_Status* status) {
 
 void TF_DeleteSession(TF_Session* s, TF_Status* status) {
   status->status = Status::OK();
+  if (s == nullptr) return;
   TF_Graph* const graph = s->graph;
   if (graph != nullptr) {
     graph->mu.lock();
diff --git a/tensorflow/c/c_api.h b/tensorflow/c/c_api.h
index c5035e0e41..c8ae6f2dd1 100644
--- a/tensorflow/c/c_api.h
+++ b/tensorflow/c/c_api.h
@@ -44,6 +44,7 @@ limitations under the License.
 // * size_t is used to represent byte sizes of objects that are
 //   materialized in the address space of the calling process.
 // * int is used as an index into arrays.
+// * Deletion functions are safe to call on nullptr.
 //
 // Questions left to address:
 // * Might at some point need a way for callers to provide their own Env.
diff --git a/tensorflow/c/c_api_test.cc b/tensorflow/c/c_api_test.cc
index c470ab5649..e674b1623c 100644
--- a/tensorflow/c/c_api_test.cc
+++ b/tensorflow/c/c_api_test.cc
@@ -1426,6 +1426,29 @@ TEST(CAPI, SavedModelNullArgsAreValid) {
   TF_DeleteStatus(s);
 }
 
+TEST(CAPI, DeletingNullPointerIsSafe) {
+  TF_Status* status = TF_NewStatus();
+
+  TF_DeleteStatus(nullptr);
+  TF_DeleteBuffer(nullptr);
+  TF_DeleteTensor(nullptr);
+  TF_DeleteSessionOptions(nullptr);
+  TF_DeleteGraph(nullptr);
+  TF_DeleteImportGraphDefOptions(nullptr);
+  TF_DeleteImportGraphDefResults(nullptr);
+  TF_DeleteFunction(nullptr);
+  TF_DeleteSession(nullptr, status);
+  EXPECT_EQ(TF_OK, TF_GetCode(status)) << TF_Message(status);
+  TF_DeletePRunHandle(nullptr);
+  TF_DeleteDeprecatedSession(nullptr, status);
+  EXPECT_EQ(TF_OK, TF_GetCode(status)) << TF_Message(status);
+  TF_DeleteDeviceList(nullptr);
+  TF_DeleteLibraryHandle(nullptr);
+  TF_DeleteApiDefMap(nullptr);
+
+  TF_DeleteStatus(status);
+}
+
 REGISTER_OP("TestOpWithNoGradient")
     .Input("x: T")
     .Output("y: T")