Merge pull request #2647 from geoffw0/modelpure

CPP: Improve strlen model

cpp/ql/src/semmle/code/cpp/commons/NullTermination.qll

@@ -80,14 +80,6 @@ predicate functionArgumentMustBeNullTerminated(Function f, int i) {
   f.(ArrayFunction).hasArrayInput(i)
   or
   f instanceof StrcatFunction and i = 0
-  or
-  f.hasName("strlen") and i = 0
-  or
-  f.hasName("strcmp") and i in [0 .. 1]
-  or
-  f.hasName("strchr") and i = 0
-  or
-  f.hasName("strstr") and i in [0 .. 1]
 }
 
 /**

cpp/ql/src/semmle/code/cpp/models/implementations/Pure.qll

@@ -30,7 +30,16 @@ class PureStrFunction extends AliasFunction, ArrayFunction, TaintFunction, SideE
         name = "strtol" or
         name = "strtoll" or
         name = "strtoq" or
-        name = "strtoul"
+        name = "strtoul" or
+        name = "wcslen"
+      )
+      or
+      hasGlobalName(name) and
+      (
+        name = "_mbslen" or
+        name = "_mbslen_l" or
+        name = "_mbstrlen" or
+        name = "_mbstrlen_l"
       )
     )
   }
@@ -39,6 +48,10 @@ class PureStrFunction extends AliasFunction, ArrayFunction, TaintFunction, SideE
     getParameter(bufParam).getUnspecifiedType() instanceof PointerType
   }
 
+  override predicate hasArrayWithNullTerminator(int bufParam) {
+    getParameter(bufParam).getUnspecifiedType() instanceof PointerType
+  }
+
   override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
     exists(ParameterIndex i |
       input.isParameter(i) and