a

libc/utfrune.c

@@ -0,0 +1,30 @@
+#include <u.h>
+#include <libc.h>
+
+char*
+utfrune(char *s, long c)
+{
+	long c1;
+	Rune r;
+	int n;
+
+	if(c < Runesync)		/* not part of utf sequence */
+		return strchr(s, c);
+
+	for(;;) {
+		c1 = *(uchar*)s;
+		if(c1 < Runeself) {	/* one byte rune */
+			if(c1 == 0)
+				return 0;
+			if(c1 == c)
+				return s;
+			s++;
+			continue;
+		}
+		n = chartorune(&r, s);
+		if(r == c)
+			return s;
+		s += n;
+	}
+	return 0;
+}