Factor out readrune and writerune

libutf/readrune.c

@@ -0,0 +1,46 @@
+/* See LICENSE file for copyright and license details. */
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "../utf.h"
+
+int
+readrune(const char *file, FILE *fp, Rune *r)
+{
+	char buf[UTFmax];
+	int c, i;
+
+	if ((c = fgetc(fp)) == EOF) {
+		if (ferror(fp)) {
+			fprintf(stderr, "%s: read error: %s\n",
+				file, strerror(errno));
+			exit(1);
+		}
+		return 0;
+	}
+
+	if (c < Runeself) {
+		*r = (Rune)c;
+		return 1;
+	}
+
+	buf[0] = c;
+	for (i = 1; ;) {
+		if ((c = fgetc(fp)) == EOF) {
+			if (ferror(fp)) {
+				fprintf(stderr, "%s: read error: %s\n",
+					file, strerror(errno));
+				exit(1);
+			}
+			return 0;
+		}
+		buf[i++] = c;
+		if (fullrune(buf, i)) {
+			chartorune(r, buf);
+			break;
+		}
+	}
+	return 1;
+}