Refine RULE-21-13 and its unit test

Author: jeongsoolee09

c/misra/src/rules/RULE-21-13/CtypeFunctionArgNotUnsignedCharOrEof.ql

@@ -20,31 +20,23 @@ class CtypeFunction extends Function {
   CtypeFunction() { this.getADeclaration().getAFile().(HeaderFile).getShortName() = "_ctype" }
 }
 
-predicate unsignedCharRange(int lower, int upper, EOFInvocation eof) {
-  exists(UnsignedCharType unsignedChar |
-    lower = typeLowerBound(unsignedChar) and
-    upper = upperBound(eof.getExpr()) and
-    typeLowerBound(unsignedChar) <= lowerBound(eof.getExpr()) and
-    upperBound(eof.getExpr()) <= typeUpperBound(unsignedChar)
-  )
-}
-
-predicate isEquivToEOF(Expr expr) {
-  exists(EOFInvocation eof | DataFlow::localFlow(DataFlow::exprNode(eof.getExpr()), DataFlow::exprNode(expr)))
-}
-
 from FunctionCall ctypeCall
 where
   not isExcluded(ctypeCall,
     StandardLibraryFunctionTypesPackage::ctypeFunctionArgNotUnsignedCharOrEofQuery()) and
-  exists(CtypeFunction ctype, UnsignedCharType unsignedChar |
+  not exists(CtypeFunction ctype, UnsignedCharType unsignedChar |
     ctypeCall = ctype.getACallToThisFunction()
   |
-  /* The argument's value should be in the `unsigned char` range. */
+    /* The argument's value should be in the `unsigned char` range. */
     typeLowerBound(unsignedChar) <= lowerBound(ctypeCall.getAnArgument().getExplicitlyConverted()) and // consider casts
     upperBound(ctypeCall.getAnArgument().getExplicitlyConverted()) <= typeUpperBound(unsignedChar)
     or
-  /* The argument's value is reachable from EOF. */
-    exists(EOFInvocation eof | DataFlow::localFlow(DataFlow::exprNode(eof.getExpr()), DataFlow::exprNode(ctypeCall.getAnArgument())))
+    /* The argument's value is reachable from EOF. */
+    exists(EOFInvocation eof |
+      DataFlow::localFlow(DataFlow::exprNode(eof.getExpr()),
+        DataFlow::exprNode(ctypeCall.getAnArgument()))
+    )
   )
-select ctypeCall, ctypeCall.getAnArgument()
+select ctypeCall,
+  "The <ctype.h> function $@ accepts an argument $@ that is not unsigned char nor an EOF.",
+  ctypeCall, ctypeCall.getTarget(), ctypeCall.getAnArgument(), ctypeCall.getAnArgument().toString()

c/misra/test/rules/RULE-21-13/test.c

@@ -6,13 +6,18 @@ void sample() {
   int r1 = isalnum(c1); // COMPLIANT: ASCII 99 is within unsigned char range of [0, 255]
   unsigned char x1 = EOF;
   unsigned char x2 = x1;
-  unsigned char c2 = x2 + 1;
+  unsigned char c2 = x2;
   int r2 = isdigit(c2); // COMPLIANT: EOF (-1)
 
   int x3 = 256;
   int x4 = x3;
   int c3 = x4;
   int r3 = islower(c3); // NON_COMPLIANT: is outside unsigned char range of[0, 255]
+
+  unsigned char x5 = EOF;
+  unsigned char x6 = x5;
+  int c4 = x6 + 10000;
+  int r4 = isdigit(c4); // NON_COMPLIANT: is outside unsigned char range of[0, 255]
 }
 
 int main() { return 0; }