[PATCH] BaseTools: report error if flag in LABEL() invalid

["Feng, YunhuaX" <yunhuax.feng@intel.com>]

Flag in LABEL() is not valid C variable name, will
report error

Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yunhua Feng <yunhuax.feng@intel.com>
---
 BaseTools/Source/Python/Common/Expression.py | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/BaseTools/Source/Python/Common/Expression.py b/BaseTools/Source/Python/Common/Expression.py
index f1516d5c7b..40e6d32280 100644
--- a/BaseTools/Source/Python/Common/Expression.py
+++ b/BaseTools/Source/Python/Common/Expression.py
@@ -117,10 +117,16 @@ def SplitPcdValueString(String):
         raise BadExpression(ERR_STRING_TOKEN % Item)
     if Item:
         RetList.append(Item)
     return RetList
 
+def IsValidCString(Str):
+    ValidString = re.compile(r'[_a-zA-Z][_0-9a-zA-Z]*$')
+    if not ValidString.match(Str):
+        return False
+    return True
+
 ## ReplaceExprMacro
 #
 def ReplaceExprMacro(String, Macros, ExceptionList = None):
     StrList = SplitString(String)
     for i, String in enumerate(StrList):
@@ -883,17 +889,17 @@ class ValueExpressionEx(ValueExpression):
                         ReOffset = re.compile('OFFSET_OF\((\w+)\)')
                         LabelOffset = 0
                         for Index, Item in enumerate(PcdValueList):
                             # compute byte offset of every LABEL
                             Item = Item.strip()
-                            try:
-                                LabelList = ReLabel.findall(Item)
+                            LabelList = ReLabel.findall(Item)
+                            if LabelList:
                                 for Label in LabelList:
+                                    if not IsValidCString(Label):
+                                        raise BadExpression('%s is invalid c variable string' % Label)
                                     if Label not in LabelDict.keys():
                                         LabelDict[Label] = str(LabelOffset)
-                            except:
-                                pass
                             if Item.startswith('UINT8'):
                                 LabelOffset = LabelOffset + 1
                             elif Item.startswith('UINT16'):
                                 LabelOffset = LabelOffset + 2
                             elif Item.startswith('UINT32'):
-- 
2.12.2.windows.2