setAttribute: Reject Empty Strings (openPMD#1087)

* setAttribute: Reject Empty Strings

Some backends, especially HDF5, do not allow us to define zero-sized
strings. We thus need to catch this in the frontend and forward the
restriction to the user.

* Test: setAttribute("key", "") throws

* setAttribute Check: C++14 compatible

Author: ax3l

include/openPMD/backend/Attributable.hpp

@@ -31,6 +31,7 @@
 #include <vector>
 #include <string>
 #include <cstddef>
+#include <type_traits>
 
 // expose private and protected members for invasive testing
 #ifndef OPENPMD_protected
@@ -83,8 +84,29 @@ class AttributableData
 private:
     A_MAP m_attributes;
 };
+
+/** Verify values of attributes in the frontend
+ *
+ * verify string attributes are not empty (backend restriction, e.g., HDF5)
+ */
+template< typename T >
+inline void
+attr_value_check( std::string const /* key */, T /* value */ )
+{
 }
 
+template< >
+inline void
+attr_value_check( std::string const key, std::string const value )
+{
+    if( value.empty() )
+        throw std::runtime_error(
+                "[setAttribute] Value for string attribute '" + key +
+                "' must not be empty!" );
+}
+
+} // namespace internal
+
 /** @brief Layer to manage storage of attributes associated with file objects.
  *
  * Mandatory and user-defined Attributes and their data for every object in the
@@ -394,6 +416,8 @@ template< typename T >
 inline bool
 AttributableInterface::setAttribute( std::string const & key, T value )
 {
+    internal::attr_value_check( key, value );
+
     auto & attri = get();
     if(IOHandler() && Access::READ_ONLY == IOHandler()->m_frontendAccess )
     {
@@ -420,6 +444,7 @@ AttributableInterface::setAttribute( std::string const & key, T value )
         return false;
     }
 }
+
 inline bool
 AttributableInterface::setAttribute( std::string const & key, char const value[] )
 {

test/ParallelIOTest.cpp

@@ -13,6 +13,7 @@
 #   include <fstream>
 #   include <iostream>
 #   include <algorithm>
+#   include <stdexcept>
 #   include <string>
 #   include <vector>
 #   include <list>
@@ -226,6 +227,7 @@ TEST_CASE( "hdf5_write_test", "[parallel][hdf5]" )
     auto mpi_rank = static_cast<uint64_t>(mpi_r);
     Series o = Series("../samples/parallel_write.h5", Access::CREATE, MPI_COMM_WORLD);
 
+    REQUIRE_THROWS_AS(o.setAuthor(""), std::runtime_error);
     o.setAuthor("Parallel HDF5");
     ParticleSpecies& e = o.iterations[1].particles["e"];
 

test/SerialIOTest.cpp

@@ -24,6 +24,7 @@
 #include <list>
 #include <memory>
 #include <numeric>
+#include <stdexcept>
 #include <sstream>
 #include <string>
 #include <tuple>
@@ -1785,6 +1786,7 @@ void bool_test(const std::string & backend)
     {
         Series o = Series("../samples/serial_bool." + backend, Access::CREATE);
 
+        REQUIRE_THROWS_AS(o.setAuthor(""), std::runtime_error);
         o.setAttribute("Bool attribute (true)", true);
         o.setAttribute("Bool attribute (false)", false);
     }