util/tolower: remove magic and add knot_strtolower()

src/libknot/util/tolower.c

@@ -17,7 +17,7 @@
 #include <config.h>
 #include "util/tolower.h"
 
-const uint8_t char_table[CHAR_TABLE_SIZE] = {
+const uint8_t char_table[KNOT_CHAR_TABLE_SIZE] = {
 	'\x00',
 	'\x01',
 	'\x02',

src/libknot/util/tolower.h

@@ -28,32 +28,46 @@
 #define _KNOT_TOLOWER_H_
 
 #include <stdint.h>
+#include <stdlib.h>
 
 /*! \brief Size of the character conversion table. */
-#define KNOT_CHAR_TABLE_SIZE 256
-
-enum {
-	/*! \brief Size of the character conversion table. */
-	CHAR_TABLE_SIZE = KNOT_CHAR_TABLE_SIZE
-};
+#define KNOT_CHAR_TABLE_SIZE (UINT8_MAX + 1)
 
 /*! \brief Character table mapping uppercase letters to lowercase. */
-extern const uint8_t char_table[CHAR_TABLE_SIZE];
+extern const uint8_t char_table[KNOT_CHAR_TABLE_SIZE];
 
 /*!
- * \brief Converts ASCII character to lowercase.
+ * \brief Converts binary character to lowercase.
  *
- * \param c ASCII character code.
+ * \param c  Character code.
  *
  * \return \a c converted to lowercase (or \a c if not applicable).
  */
 static inline uint8_t knot_tolower(uint8_t c) {
-#if KNOT_CHAR_TABLE_SIZE < 256
-	assert(c < CHAR_TABLE_SIZE);
-#endif
 	return char_table[c];
 }
 
+/*!
+ * \brief Convert binary data to lowercase (if lowercase equivalent exists).
+ *
+ * \param data  Binary input string.
+ * \param size  Size of the input string
+ *
+ * \return Lowercase representation of the input string.
+ */
+static inline uint8_t *knot_strtolower(const uint8_t *data, size_t size)
+{
+	uint8_t *result = (uint8_t *)malloc(size);
+	if (!result)
+		return NULL;
+
+	for (size_t i = 0; i < size; ++i) {
+		result[i] = knot_tolower(data[i]);
+	}
+
+	return result;
+}
+
 #endif /* _KNOT_TOLOWER_H_ */
 
 /*! @} */