[*] Initial commit

lonetix/utf/utfutf.c

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+/**
+ * \file utf/utfutf.c
+ *
+ * Implements `utfutf()`.
+ *
+ * \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
+ * \author    Lorenzo Cogotti
+ */
+
+/*
+ * This work is derived from Plan 9 libutf, see utf/utf.h for details.
+ * Original license terms follow:
+ *
+ * The authors of this software are Rob Pike and Ken Thompson.
+ *              Copyright (c) 2002 by Lucent Technologies.
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose without fee is hereby granted, provided that this entire notice
+ * is included in all copies of any software which is or includes a copy
+ * or modification of this software and in all copies of the supporting
+ * documentation for such software.
+ * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE
+ * ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
+ * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
+ *
+ * The original libutf library is available at: https://9fans.github.io/plan9port/unix/libutf.tgz
+ */
+
+#include "utf/utf.h"
+
+#include <string.h>
+
+char *utfutf(const char *s1, const char *s2)
+{
+	Rune   f;
+	size_t n1 = chartorune(&f, s2);
+	if (f <= RUNE_SYNC)  // represents self
+		return strstr(s1, s2);
+
+	size_t n2 = strlen(s2);
+	for (char *p = (char *) s1; (p = utfrune(p, f)) != NULL; p += n1) {
+		if (strncmp(p, s2, n2) == 0)
+			return p;
+	}
+	return NULL;
+}