enum: Return boolean result for enum_from_name() lookup

Handling the result for enum_from_name() is difficult, as checking for
negative return values requires a cast if the enum type is unsigned. The new
signature clearly differentiates lookup result from lookup value.

Further, this actually allows to convert real -1 enum values, which could not
be distinguished from "not-found" and the -1 return value.

This also fixes several clang warnings where enums are unsigned.

src/libstrongswan/tests/suites/test_enum.c

@@ -120,41 +120,50 @@ END_TEST
  */
 
 static struct {
+	bool found;
 	int val;
 	char *str;
 } enum_tests_cont[] = {
-	{CONT1, "CONT1"},
-	{CONT2, "CONT2"},
-	{CONT2, "CoNt2"},
-	{CONT3, "CONT3"},
-	{CONT4, "CONT4"},
-	{CONT5, "CONT5"},
-	{-1, "asdf"},
-	{-1, ""},
-	{-1, NULL},
+	{TRUE, CONT1, "CONT1"},
+	{TRUE, CONT2, "CONT2"},
+	{TRUE, CONT2, "CoNt2"},
+	{TRUE, CONT3, "CONT3"},
+	{TRUE, CONT4, "CONT4"},
+	{TRUE, CONT5, "CONT5"},
+	{FALSE, 0, "asdf"},
+	{FALSE, 0, ""},
+	{FALSE, 0, NULL},
 }, enum_tests_split[] = {
-	{SPLIT1, "SPLIT1"},
-	{SPLIT1, "split1"},
-	{SPLIT2, "SPLIT2"},
-	{SPLIT2, "SpLiT2"},
-	{SPLIT3, "SPLIT3"},
-	{SPLIT4, "SPLIT4"},
-	{SPLIT5, "SPLIT5"},
-	{-1, "asdf"},
-	{-1, ""},
-	{-1, NULL},
+	{TRUE, SPLIT1, "SPLIT1"},
+	{TRUE, SPLIT1, "split1"},
+	{TRUE, SPLIT2, "SPLIT2"},
+	{TRUE, SPLIT2, "SpLiT2"},
+	{TRUE, SPLIT3, "SPLIT3"},
+	{TRUE, SPLIT4, "SPLIT4"},
+	{TRUE, SPLIT5, "SPLIT5"},
+	{FALSE, 0, "asdf"},
+	{FALSE, 0, ""},
+	{FALSE, 0, NULL},
 };
 
 START_TEST(test_enum_from_name_cont)
 {
-	int val = enum_from_name(test_enum_cont_names, enum_tests_cont[_i].str);
+	int val = 0;
+	bool found;
+
+	found = enum_from_name(test_enum_cont_names, enum_tests_cont[_i].str, &val);
+	ck_assert(enum_tests_cont[_i].found == found);
 	ck_assert_int_eq(val, enum_tests_cont[_i].val);
 }
 END_TEST
 
 START_TEST(test_enum_from_name_split)
 {
-	int val = enum_from_name(test_enum_split_names, enum_tests_split[_i].str);
+	int val = 0;
+	bool found;
+
+	found = enum_from_name(test_enum_split_names, enum_tests_split[_i].str, &val);
+	ck_assert(enum_tests_split[_i].found == found);
 	ck_assert_int_eq(val, enum_tests_split[_i].val);
 }
 END_TEST

src/libstrongswan/utils/enum.c

@@ -40,7 +40,7 @@ char *enum_to_name(enum_name_t *e, int val)
 /**
  * See header.
  */
-int enum_from_name(enum_name_t *e, char *name)
+bool enum_from_name_as_int(enum_name_t *e, const char *name, int *val)
 {
 	do
 	{
@@ -50,12 +50,13 @@ int enum_from_name(enum_name_t *e, char *name)
 		{
 			if (name && strcaseeq(name, e->names[i]))
 			{
-				return e->first + i;
+				*val = e->first + i;
+				return TRUE;
 			}
 		}
 	}
 	while ((e = e->next));
-	return -1;
+	return FALSE;
 }
 
 /**

src/libstrongswan/utils/enum.h

@@ -120,9 +120,30 @@ char *enum_to_name(enum_name_t *e, int val);
  *
  * @param e		enum names for this enum value
  * @param name	name to get enum value for
- * @return		enum value, -1 if not found
+ * @þaram valp	variable sized pointer receiving value
+ * @return		TRUE if enum name found, FALSE otherwise
  */
-int enum_from_name(enum_name_t *e, char *name);
+#define enum_from_name(e, name, valp) ({ \
+	int _val; \
+	int _found = enum_from_name_as_int(e, name, &_val); \
+	if (_found) \
+	{ \
+		*(valp) = _val; \
+	} \
+	_found; })
+
+/**
+ * Convert a enum string back to its enum value, integer pointer variant.
+ *
+ * This variant takes integer pointer only, use enum_from_name() to pass
+ * enum type pointers for the result.
+ *
+ * @param e		enum names for this enum value
+ * @param name	name to get enum value for
+ * @þaram val	integer pointer receiving value
+ * @return		TRUE if enum name found, FALSE otherwise
+ */
+bool enum_from_name_as_int(enum_name_t *e, const char *name, int *val);
 
 /**
  * printf hook function for enum_names_t.