Updated installer with custom action

installer/src/installer-lib/record.cpp

 /**
  * \file record.cpp Implementation of Session class.
  */
 
 #include "record.h"
 #include "msiquery.h"
 
 //-----------------------------------------------------------------------------------------
 // Record
 //-----------------------------------------------------------------------------------------
 Record::Record( unsigned int n_fields )
-  : n_fields( n_fields )
 {
   _handle = MsiCreateRecord( n_fields ) ;
   if ( ! _handle )
   {
     throw std::runtime_error( "Failed to create record" ) ;
   }
 }
 
 Record::~Record()
 {
-  MsiCloseHandle( _handle ) ;
+  if ( _handle != 0 )
+  {
+    MsiCloseHandle( _handle ) ;
+  }
 }
 
-void 
-Record::assign_string( unsigned int field_index, std::wstring value )
+void Record::only_non_null()
 {
-  MsiRecordSetString( _handle, field_index, value.c_str() ) ;
+  if ( _handle == 0 )
+  {
+    throw std::runtime_error( "Operation only permitted for non-null objects" ) ;
+  }
+}
+
+void Record::assign_string( unsigned int field_index, const char *value )
+{
+  only_non_null() ;
+  MsiRecordSetStringA( _handle, field_index, value ) ;
+}
+
+void Record::assign_string( unsigned int field_index, const wchar_t *value )
+{
+  only_non_null() ;
+  MsiRecordSetStringW( _handle, field_index, value ) ;
+}
+
+/**
+ * \par Implementation
+ *    - MSDN [MsiRecordGetString](http://msdn.microsoft.com/en-us/library/aa370368%28v=vs.85%29.aspx)
+ */
+std::wstring Record::value_string( unsigned int field_index )
+{
+  static wchar_t initial_buffer[ 256 ] = L"" ;
+  DWORD length = 255 ; // one less than the buffer length to hold a terminating null character
+  UINT x = MsiRecordGetStringW( _handle, field_index, initial_buffer, & length ) ;
+  if ( x == ERROR_SUCCESS )
+  {
+    return std::wstring( initial_buffer ) ;
+  }
+  if ( x == ERROR_MORE_DATA )
+  {
+    // Future: handle longer strings.
+    throw std::runtime_error( "Record strings longer than 255 not supported yet" ) ;
+  }
+  throw std::runtime_error( "Error retrieving string from record" ) ;
+}
+
+size_t Record::n_fields() const
+{
+   unsigned int x = MsiRecordGetFieldCount( _handle ) ;
+   if ( x == 0xFFFFFFFF )

[Oleksandr, 2014/03/12 19:26:04]

We use INVALID_HANDLE_VALUE pretty much everywhere else

[Eric, 2014/03/17 12:26:46]

This is the return value as documented on the MsiRecordGetFieldCount page. On
the other hand, that page also documents -1 as a possible return value for an
unsigned int. But whatever it is, it's not a handle value, nor an error-handle.

+   {
+     throw std::runtime_error( "Invalid handle" ) ;
+   }
+   return x ;
 }