!12469 [MD] fix bug in cifar10/100 to mindrecord

From: @liyong126
Reviewed-by: @savoygll,@heleiwang,@liucunwei
Signed-off-by: @savoygll,@liucunwei

mindspore/dataset/transforms/c_transforms.py

@@ -321,14 +321,16 @@ class Duplicate(cde.DuplicateOp):
 
 class Unique(cde.UniqueOp):
     """
-    Return an output tensor containing all the unique elements of the input tensor in
+    Perform the unique operation on the input tensor, only support transform one column each time.
-    the same order that they occur in the input tensor.
 
-    Also return an index tensor that contains the index of each element of the
+    Return 3 tensor: unique output tensor, index tensor, count tensor.
-    input tensor in the Unique output tensor.
 
-    Finally, return a count tensor that contains the count of each element of
+    Unique output tensor contains all the unique elements of the input tensor
-    the output tensor in the input tensor.
+    in the same order that they occur in the input tensor.
+
+    Index tensor that contains the index of each element of the input tensor in the unique output tensor.
+
+    Count tensor that contains the count of each element of the output tensor in the input tensor.
 
     Note:
         Call batch op before calling this function.

mindspore/mindrecord/tools/cifar10.py

@@ -57,7 +57,13 @@ def restricted_loads(s):
     if isinstance(s, str):
         raise TypeError("can not load pickle from unicode string")
     f = io.BytesIO(s)
-    return RestrictedUnpickler(f, encoding='bytes').load()
+    try:
+        return RestrictedUnpickler(f, encoding='bytes').load()
+    except pickle.UnpicklingError:
+        raise RuntimeError("Not a valid Cifar10 Dataset.")
+    else:
+        raise RuntimeError("Unexpected error while Unpickling Cifar10 Dataset.")
+
 
 class Cifar10:
     """

mindspore/mindrecord/tools/cifar100.py

@@ -56,7 +56,13 @@ def restricted_loads(s):
     if isinstance(s, str):
         raise TypeError("can not load pickle from unicode string")
     f = io.BytesIO(s)
-    return RestrictedUnpickler(f, encoding='bytes').load()
+    try:
+        return RestrictedUnpickler(f, encoding='bytes').load()
+    except pickle.UnpicklingError:
+        raise RuntimeError("Not a valid Cifar100 Dataset.")
+    else:
+        raise RuntimeError("Unexpected error while Unpickling Cifar100 Dataset.")
+
 
 class Cifar100:
     """