C API: Avoid converting uninitialized tensorflow::Tensor to TF_Tensor*

And return error messages instead of CHECK failing when the conversion
fails.

PiperOrigin-RevId: 163863981

tensorflow/c/c_api.cc

@@ -488,7 +488,13 @@ Status TF_TensorToTensor(const TF_Tensor* src, Tensor* dst) {
 }
 
 // Non-static for testing.
-TF_Tensor* TF_TensorFromTensor(const tensorflow::Tensor& src) {
+TF_Tensor* TF_TensorFromTensor(const tensorflow::Tensor& src,
+                               TF_Status* status) {
+  if (!src.IsInitialized()) {
+    status->status = FailedPrecondition(
+        "attempt to use a tensor with an uninitialized value");
+    return nullptr;
+  }
   if (src.dtype() == DT_RESOURCE) {
     DCHECK_EQ(0, src.shape().dims()) << src.shape().DebugString();
     if (src.shape().dims() != 0) {
@@ -528,18 +534,26 @@ TF_Tensor* TF_TensorFromTensor(const tensorflow::Tensor& src) {
   char* dst = data_start;  // Where next string is encoded.
   size_t dst_len = size - static_cast<size_t>(data_start - base);
   tensorflow::uint64* offsets = reinterpret_cast<tensorflow::uint64*>(base);
-  TF_Status status;
   for (int i = 0; i < srcarray.size(); ++i) {
     *offsets = (dst - data_start);
     offsets++;
     const tensorflow::string& s = srcarray(i);
-    size_t consumed =
+    size_t consumed = TF_StringEncode(s.data(), s.size(), dst, dst_len, status);
-        TF_StringEncode(s.data(), s.size(), dst, dst_len, &status);
+    if (!status->status.ok()) {
-    CHECK(status.status.ok());
+      status->status = InvalidArgument(
+          "invalid string tensor encoding (string #", i, " of ",
+          srcarray.size(), "): ", status->status.error_message());
+      return nullptr;
+    }
     dst += consumed;
     dst_len -= consumed;
   }
-  CHECK_EQ(dst, base + size);
+  if (dst != base + size) {
+    status->status = InvalidArgument(
+        "invalid string tensor encoding (decoded ", (dst - base),
+        " bytes, but the tensor is encoded in ", size, " bytes");
+    return nullptr;
+  }
 
   auto dims = src.shape().dim_sizes();
   std::vector<tensorflow::int64> dimvec(dims.size());
@@ -650,7 +664,8 @@ static void TF_Run_Helper(
           static_cast<TF_DataType>(src.dtype()), src.shape());
       continue;
     }
-    c_outputs[i] = TF_TensorFromTensor(src);
+    c_outputs[i] = TF_TensorFromTensor(src, status);
+    if (!status->status.ok()) return;
   }
 }
 
@@ -1605,7 +1620,7 @@ void TF_OperationGetAttrTensor(TF_Operation* oper, const char* attr_name,
   Tensor t;
   status->status = tensorflow::GetNodeAttr(oper->node.attrs(), attr_name, &t);
   if (!status->status.ok()) return;
-  *value = TF_TensorFromTensor(t);
+  *value = TF_TensorFromTensor(t, status);
 }
 
 void TF_OperationGetAttrTensorList(TF_Operation* oper, const char* attr_name,
@@ -1616,7 +1631,7 @@ void TF_OperationGetAttrTensorList(TF_Operation* oper, const char* attr_name,
   if (!status->status.ok()) return;
   const auto len = std::min(max_values, static_cast<int>(ts.size()));
   for (int i = 0; i < len; ++i) {
-    values[i] = TF_TensorFromTensor(ts[i]);
+    values[i] = TF_TensorFromTensor(ts[i], status);
   }
 }
 

tensorflow/c/c_api_test.cc

@@ -45,7 +45,7 @@ limitations under the License.
 #include "tensorflow/core/util/equal_graph_def.h"
 
 namespace tensorflow {
-TF_Tensor* TF_TensorFromTensor(const Tensor& src);
+TF_Tensor* TF_TensorFromTensor(const Tensor& src, TF_Status* status);
 Status TF_TensorToTensor(const TF_Tensor* src, Tensor* dst);
 
 namespace {
@@ -137,6 +137,7 @@ TEST(CAPI, LibraryLoadFunctions) {
 
 void TestEncodeDecode(int line, const std::vector<string>& data) {
   const tensorflow::int64 n = data.size();
+  TF_Status* status = TF_NewStatus();
   for (const std::vector<tensorflow::int64>& dims :
        std::vector<std::vector<tensorflow::int64>>{
            {n}, {1, n}, {n, 1}, {n / 2, 2}}) {
@@ -145,7 +146,8 @@ void TestEncodeDecode(int line, const std::vector<string>& data) {
     for (tensorflow::int64 i = 0; i < src.NumElements(); ++i) {
       src.flat<string>()(i) = data[i];
     }
-    TF_Tensor* dst = TF_TensorFromTensor(src);
+    TF_Tensor* dst = TF_TensorFromTensor(src, status);
+    ASSERT_EQ(TF_OK, TF_GetCode(status)) << TF_Message(status);
 
     // Convert back to a C++ Tensor and ensure we get expected output.
     Tensor output;
@@ -157,6 +159,7 @@ void TestEncodeDecode(int line, const std::vector<string>& data) {
 
     TF_DeleteTensor(dst);
   }
+  TF_DeleteStatus(status);
 }
 
 TEST(CAPI, TensorEncodeDecodeStrings) {
@@ -914,7 +917,8 @@ TEST(CAPI, SavedModel) {
   TF_Operation* input_op =
       TF_GraphOperationByName(graph, input_op_name.c_str());
   ASSERT_TRUE(input_op != nullptr);
-  csession.SetInputs({{input_op, TF_TensorFromTensor(input)}});
+  csession.SetInputs({{input_op, TF_TensorFromTensor(input, s)}});
+  ASSERT_EQ(TF_OK, TF_GetCode(s)) << TF_Message(s);
 
   const tensorflow::string output_op_name =
       tensorflow::ParseTensorName(output_name).first.ToString();