[PATCH 1/2] lib: fix snprintf() for UTF-16 strings

[Heinrich Schuchardt]

snprintf() must return the required buffer length.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 lib/vsprintf.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 2c84649fa8..779efc30bc 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -285,15 +285,25 @@ static __maybe_unused char *string16(char *buf, char *end, u16 *s,
 	if (!(flags & LEFT))
 		for (; len < field_width; --field_width)
 			ADDCH(buf, ' ');
-	for (i = 0; i < len && buf + utf16_utf8_strnlen(str, 1) <= end; ++i) {
+	if (buf < end)
+		*buf = 0;
+	for (i = 0; i < len; ++i) {
+		int slen = utf16_utf8_strnlen(str, 1);
 		s32 s = utf16_get(&str);
 
 		if (s < 0)
 			s = '?';
-		utf8_put(s, &buf);
+		if (buf + slen < end) {
+			utf8_put(s, &buf);
+			if (buf < end)
+				*buf = 0;
+		} else {
+			buf += slen;
+		}
 	}
 	for (; len < field_width; --field_width)
 		ADDCH(buf, ' ');
+
 	return buf;
 }
 
-- 
2.33.1