BaseTools: enhance error handling for DSC file

Add logic for DSC file validation for Prebuild init. Add logic to detect
error for DSC parser when '{' is missing.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/Workspace/MetaFileParser.py

@@ -915,6 +915,8 @@ class DscParser(MetaFileParser):
             elif Line[0] == '!':
                 self._DirectiveParser()
                 continue
+            if Line[0] == TAB_OPTION_START and not self._InSubsection:
+                EdkLogger.error("Parser", FILE_READ_FAILURE, "Missing the '{' before %s in Line %s" % (Line, Index+1),ExtraData=self.MetaFile)
 
             if self._InSubsection:
                 SectionType = self._SubsectionType

BaseTools/Source/Python/Workspace/WorkspaceDatabase.py

@@ -3012,10 +3012,9 @@ determine whether database file is out of date!\n")
         return PlatformList
 
     def _MapPlatform(self, Dscfile):
-        try:
-            Platform = self.BuildObject[PathClass(Dscfile), 'COMMON']
-        except:
-            Platform = None
+        Platform = self.BuildObject[PathClass(Dscfile), 'COMMON']
+        if Platform == None:
+            EdkLogger.error('build', PARSER_ERROR, "Failed to parser DSC file: %s" % Dscfile)
         return Platform
 
     PlatformList = property(_GetPlatformList)