Custom action library, initial version

installer/src/installer-lib/session.cpp

+/**
+ * \file session.cpp Implementation of Session class.
+ */
+
+#include "session.h"
+#include "property.h"
+#include "msiquery.h"
+
+//-----------------------------------------------------------------------------------------
+// Session
+//-----------------------------------------------------------------------------------------
+Session::Session( MSIHANDLE handle, std::wstring name )
+  : handle( handle ), 
+  log_prefix( name + L": " )
+{
+  log( L"Entering custom action" ) ;
+}
+
+/**
+ * \par Implementation Notes
+ *    The session handle doesn't need to be closed.
+ *    It's provided as an argument to the custom action at the outset, and we do not manage its life cycle.
+ */
+Session::~Session()
+{
+  log( L"Exiting custom action" ) ;
+}
+
+/**
+ * \par Implementation Notes
+ *    To write to the installation log, we use a call to MsiProcessMessage with message type INSTALLMESSAGE_INFO.
+ *    The text to be written needs to go in a "record" (yes, a database record) that acts as an argument vector.
+ *    For the message type we're using, we need only a record with a single field.
+ *
+ * \sa MSDN "MsiProcessMessage function"
+ *    http://msdn.microsoft.com/en-us/library/windows/desktop/aa370354%28v=vs.85%29.aspx
+ *    MsiProcessMessage is mostly for user interaction with message boxes, but it's also the access to the installation log.
+ */
+void Session::log( std::wstring message )
+{
+  Record r = Record( 1 );
+  r.assign_string( 0, log_prefix + message );
+  int e = MsiProcessMessage( handle, INSTALLMESSAGE_INFO, r.handle() ) ;
+  if ( e != IDOK )
+  {
+    throw std::runtime_error( "Did not succeed writing to log." ) ;
+  }
+}
+
+Immediate_Session::Immediate_Session( MSIHANDLE handle, std::wstring name )
+  : Session( handle, name )
+{
+}