ARROW-253: restrict ints to 8, 16, 32, or 64 bits in V1

Author: julienledem

cpp/src/arrow/ipc/metadata-internal.cc

@@ -55,12 +55,12 @@ const std::shared_ptr<DataType> DOUBLE = std::make_shared<DoubleType>();
 
 static Status IntFromFlatbuffer(
     const flatbuf::Int* int_data, std::shared_ptr<DataType>* out) {
-  if (int_data->bitWidth() % 8 != 0) {
-    return Status::NotImplemented("Integers not in cstdint are not implemented");
-  }
   if (int_data->bitWidth() > 64) {
     return Status::NotImplemented("Integers with more than 64 bits not implemented");
   }
+  if (int_data->bitWidth() < 8) {
+    return Status::NotImplemented("Integers with less than 8 bits not implemented");
+  }
 
   switch (int_data->bitWidth()) {
     case 8:
@@ -76,8 +76,7 @@ static Status IntFromFlatbuffer(
       *out = int_data->is_signed() ? INT64 : UINT64;
       break;
     default:
-      *out = nullptr;
-      break;
+      return Status::NotImplemented("Integers not in cstdint are not implemented");
   }
   return Status::OK();
 }

format/Message.fbs

@@ -24,7 +24,7 @@ table Bit {
 }
 
 table Int {
-  bitWidth: int; // 1 to 64
+  bitWidth: int; // restricted to 8, 16, 32, and 64 in v1
   is_signed: bool;
 }