lib: wchar: add wctomb and mbtowc

We currently convert wchar_t to char by truncating to 8-bit.
In future, we may want to do UTF-16 to UTF-8 conversion.
Prepare for this by wrapping each conversion direction in a function.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20211122084732.2597109-18-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 20 insertions, 2 deletions

diff --git a/lib/wchar.c b/lib/wchar.c
index 4d49431e86..3be228b5a7 100644
--- a/lib/wchar.c
+++ b/lib/wchar.c
@@ -44,12 +44,30 @@ wchar_t *strdup_wchar(const wchar_t *src)
 	return tmp;
 }
 
+int mbtowc(wchar_t *pwc, const char *s, size_t n)
+{
+	if (!s)
+		return 0; /* we don't mantain a non-trivial shift state */
+
+	if (n < 1)
+		return -1;
+
+	*pwc = *s;
+	return 1;
+}
+
+int wctomb(char *s, wchar_t wc)
+{
+	*s = wc & 0xFF;
+	return 1;
+}
+
 char *strcpy_wchar_to_char(char *dst, const wchar_t *src)
 {
 	char *ret = dst;
 
 	while (*src)
-		*dst++ = *src++ & 0xff;
+		wctomb(dst++, *src++);
 
 	*dst = 0;
 
@@ -61,7 +79,7 @@ wchar_t *strcpy_char_to_wchar(wchar_t *dst, const char *src)
 	wchar_t *ret = dst;
 
 	while (*src)
-		*dst++ = *src++;
+		mbtowc(dst++, src++, 1);
 
 	*dst = 0;