1 files changed, 138 insertions, 0 deletions
diff --git a/src/utf8.c b/src/utf8.c
new file mode 100644
index 0000000..d766ee6
--- /dev/null
+++ b/src/utf8.c
@@ -0,0 +1,138 @@
+/*
+ * utf8.c: UTF-8 validation
+ *
+ * Based on glib's gutf8.c, which is:
+ * Copyright (C) 1999 Tom Tromey
+ * Copyright (C) 2000 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <https://www.gnu.org/licenses/>.
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif /* HAVE_CONFIG_H */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "attribute.h"
+
+#include "manconfig.h"
+
+#include "utf8.h"
+
+#define VALIDATE_BYTE(mask, expect)                             \
+  do {                                                          \
+    if (UNLIKELY ((*(unsigned char *) p & (mask)) != (expect))) \
+      goto error;                                               \
+  } while (0)
+
+/* see IETF RFC 3629 Section 4 */
+
+static const char * ATTRIBUTE_PURE fast_validate_len (const char *str,
+						      size_t max_len)
+{
+	const char *p;
+	const char *end = str + max_len;
+
+	for (p = str; p < end && *p; p++) {
+		const char *last;
+
+		if (*(unsigned char *) p < 128)
+			continue;
+
+		last = p;
+		if (*(unsigned char *) p < 0xe0) {
+			/* 110xxxxx */
+			if (UNLIKELY (end - p < 2))
+				goto error;
+
+			if (UNLIKELY (*(unsigned char *) p < 0xc2))
+				goto error;
+		} else if (*(unsigned char *)p < 0xf0) {
+			/* 1110xxxx */
+			if (UNLIKELY (end - p < 3))
+				goto error;
+
+			switch (*(unsigned char *) p++ & 0x0f) {
+				case 0:
+					/* 0xa0 ... 0xbf */
+					VALIDATE_BYTE (0xe0, 0xa0);
+					break;
+				case 0x0d:
+					/* 0x80 ... 0x9f */
+					VALIDATE_BYTE (0xe0, 0x80);
+					break;
+				default:
+					/* 10xxxxxx */
+					VALIDATE_BYTE (0xc0, 0x80);
+			}
+		} else if (*(unsigned char *) p < 0xf5) {
+			/* 11110xxx excluding out-of-range */
+			if (UNLIKELY (end - p < 4))
+				goto error;
+
+			switch (*(unsigned char *) p++ & 0x07) {
+				case 0:
+					/* 0x90 ... 0xbf */
+					VALIDATE_BYTE (0xc0, 0x80);
+					if (UNLIKELY ((*(unsigned char *) p &
+						      0x30) == 0))
+						goto error;
+					break;
+				case 4:
+					/* 0x80 ... 0x8f */
+					VALIDATE_BYTE(0xf0, 0x80);
+					break;
+				default:
+					/* 10xxxxxx */
+					VALIDATE_BYTE(0xc0, 0x80);
+			}
+			p++;
+			/* 10xxxxxx */
+			VALIDATE_BYTE(0xc0, 0x80);
+		} else
+			goto error;
+
+		p++;
+		/* 10xxxxxx */
+		VALIDATE_BYTE(0xc0, 0x80);
+
+		continue;
+
+error:
+		return last;
+	}
+
+	return p;
+}
+
+/* Validates UTF-8 encoded text.  str is the text to validate; max_len is
+ * the number of bytes to validate.
+ *
+ * Note that utf8_validate() returns false if any of the max_len bytes are
+ * NUL.
+ *
+ * Returns true if the text was valid UTF-8.
+ */
+bool ATTRIBUTE_PURE utf8_validate_len (const char *str, size_t max_len)
+{
+	const char *p;
+
+	p = fast_validate_len (str, max_len);
+
+	return p == str + max_len;
+}