[PATCH 0/2] lib: fix snprintf() for UTF-16 strings

[PATCH 0/2] lib: fix snprintf() for UTF-16 strings

[Heinrich Schuchardt]

Up to now printing UTF-16 strings with snprintf() resulted in correct
truncation of printed strings. But the returned required buffer length
was incorrect.

* fix function string16()
* provide a unit test

Heinrich Schuchardt (2):
  lib: fix snprintf() for UTF-16 strings
  test: test UTF-16 truncation in sprintf()

 lib/vsprintf.c    | 14 ++++++++++++--
 test/unicode_ut.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)

-- 
2.33.1

[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@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

[PATCH 2/2] test: test UTF-16 truncation in sprintf()

[Heinrich Schuchardt]

Check that snprintf() returns the correct required buffer length and prints
the correct string for UTF-16 strings.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---
 test/unicode_ut.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/test/unicode_ut.c b/test/unicode_ut.c
index a16dd09579..9b3b9d4f08 100644
--- a/test/unicode_ut.c
+++ b/test/unicode_ut.c
@@ -97,6 +97,7 @@ UNICODE_TEST(unicode_test_u16_strcpy);
 static int unicode_test_string16(struct unit_test_state *uts)
 {
 	char buf[20];
+	int ret;
 
 	/* Test length and precision */
 	memset(buf, 0xff, sizeof(buf));
@@ -130,6 +131,36 @@ static int unicode_test_string16(struct unit_test_state *uts)
 	sprintf(buf, "%ls", i3);
 	ut_asserteq_str("i3?", buf);
 
+	memset(buf, 0xff, sizeof(buf));
+	ret = snprintf(buf, 4, "%ls", c1);
+	ut_asserteq(6, ret);
+	ut_asserteq_str("U-B", buf);
+
+	memset(buf, 0xff, sizeof(buf));
+	ret = snprintf(buf, 6, "%ls", c2);
+	ut_asserteq_str("kafb", buf);
+	ut_asserteq(9, ret);
+
+	memset(buf, 0xff, sizeof(buf));
+	ret = snprintf(buf, 7, "%ls", c2);
+	ut_asserteq_str("kafb\xC3\xA1", buf);
+	ut_asserteq(9, ret);
+
+	memset(buf, 0xff, sizeof(buf));
+	ret = snprintf(buf, 8, "%ls", c3);
+	ut_asserteq_str("\xE6\xBD\x9C\xE6\xB0\xB4", buf);
+	ut_asserteq(9, ret);
+
+	memset(buf, 0xff, sizeof(buf));
+	ret = snprintf(buf, 11, "%ls", c4);
+	ut_asserteq_str("\xF0\x90\x92\x8D\xF0\x90\x92\x96", buf);
+	ut_asserteq(12, ret);
+
+	memset(buf, 0xff, sizeof(buf));
+	ret = snprintf(buf, 4, "%ls", c4);
+	ut_asserteq_str("", buf);
+	ut_asserteq(12, ret);
+
 	return 0;
 }
 UNICODE_TEST(unicode_test_string16);
-- 
2.33.1

Re: [PATCH 0/2] lib: fix snprintf() for UTF-16 strings

[Simon Glass]

Hi Heinrich,

On Sat, 29 Jan 2022 at 10:40, Heinrich Schuchardt
<heinrich.schuchardt@canonical.com> wrote:
>
> Up to now printing UTF-16 strings with snprintf() resulted in correct
> truncation of printed strings. But the returned required buffer length
> was incorrect.
>
> * fix function string16()
> * provide a unit test
>
> Heinrich Schuchardt (2):
>   lib: fix snprintf() for UTF-16 strings
>   test: test UTF-16 truncation in sprintf()
>
>  lib/vsprintf.c    | 14 ++++++++++++--
>  test/unicode_ut.c | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 43 insertions(+), 2 deletions(-)
>
> --
> 2.33.1
>

Would you mind reviewing this one, please?

https://patchwork.ozlabs.org/project/uboot/list/?series=282385

I am worried there might be conflicts and it has been outstanding for
a long time.

Regards,
Simon

Re: [PATCH 2/2] test: test UTF-16 truncation in sprintf()

[Simon Glass]

On Sat, 29 Jan 2022 at 10:40, Heinrich Schuchardt
<heinrich.schuchardt@canonical.com> wrote:
>
> Check that snprintf() returns the correct required buffer length and prints
> the correct string for UTF-16 strings.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> ---
>  test/unicode_ut.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>

Reviewed-by: Simon Glass <sjg@chromium.org>