Addons: Added simple addon checking for CERT rule EXP42-C. Don't compare struct padding data.

addons/cert.py

@@ -14,12 +14,37 @@ import sys
 def reportError(token, severity, msg):
   sys.stderr.write('[' + token.file + ':' + str(token.linenr) + '] (' + severity + ') cert.py: ' + msg + '\n')
 
+def isLocalStruct(arg):
+    if arg and arg.str == '&' and not arg.astOperand2:
+        arg = arg.astOperand1
+    return arg and arg.variable and arg.variable.isClass and (arg.variable.isLocal or arg.variable.isArgument)
+
 def isBitwiseOp(token):
     return token and (token.str in ['&', '|', '^'])
 
 def isComparisonOp(token):
     return token and (token.str in ['==', '!=', '>', '>=', '<', '<='])
 
+
+# EXP42-C
+# do not compare padding data
+def exp42(data):
+    for token in data.tokenlist:
+        if token.str != '(' or not token.astOperand1:
+            continue
+
+        arg1 = None
+        arg2 = None
+        if token.astOperand2 and token.astOperand2.str == ',':
+            if token.astOperand2.astOperand1 and token.astOperand2.astOperand1.str == ',':
+                arg1 = token.astOperand2.astOperand1.astOperand1
+                arg2 = token.astOperand2.astOperand1.astOperand2
+
+        if token.astOperand1.str == 'memcmp' and (isLocalStruct(arg1) or isLocalStruct(arg2)):
+            reportError(token, 'style', 'EXP42-C Comparison of struct padding data')
+        if (token.astOperand1.str in ['memcpy','memmove']) and isLocalStruct(arg2):
+            reportError(token, 'style', 'EXP42-C Reading struct padding data')
+
 # EXP46-C
 # Do not use a bitwise operator with a Boolean-like operand
 #   int x = (a == b) & c;
@@ -31,4 +56,5 @@ def exp46(data):
 for arg in sys.argv[1:]:
   print('Checking ' + arg + '...')
   data = cppcheckdata.parsedump(arg)
+  exp42(data)
   exp46(data)