[PATCH 3.14 11/19] lib/ucs2_string: Add ucs2 -> utf8 helper functions

Greg Kroah-Hartman
2016-03-14T18:05:06Z

From: Peter Jones <pjones@redhat.com>

commit 73500267c930baadadb0d02284909731baf151f7 upstream.

This adds ucs2_utf8size(), which tells us how big our ucs2 string is in
bytes, and ucs2_as_utf8, which translates from ucs2 to utf8..

Signed-off-by: Peter Jones <pjones@redhat.com>
Tested-by: Lee, Chun-Yi <jlee@suse.com>
Acked-by: Matthew Garrett <mjg59@coreos.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/ucs2_string.h | 4 ++
lib/ucs2_string.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+)

--- a/include/linux/ucs2_string.h
+++ b/include/linux/ucs2_string.h
@@ -11,4 +11,8 @@ unsigned long ucs2_strlen(const ucs2_cha
unsigned long ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength);
int ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len);

+unsigned long ucs2_utf8size(const ucs2_char_t *src);
+unsigned long ucs2_as_utf8(u8 *dest, const ucs2_char_t *src,
+ unsigned long maxlength);
+
#endif /* _LINUX_UCS2_STRING_H_ */
--- a/lib/ucs2_string.c
+++ b/lib/ucs2_string.c
@@ -49,3 +49,65 @@ ucs2_strncmp(const ucs2_char_t *a, const
}
}
EXPORT_SYMBOL(ucs2_strncmp);
+
+unsigned long
+ucs2_utf8size(const ucs2_char_t *src)
+{
+ unsigned long i;
+ unsigned long j = 0;
+
+ for (i = 0; i < ucs2_strlen(src); i++) {
+ u16 c = src[i];
+
+ if (c > 0x800)
+ j += 3;
+ else if (c > 0x80)
+ j += 2;
+ else
+ j += 1;
+ }
+
+ return j;
+}
+EXPORT_SYMBOL(ucs2_utf8size);
+
+/*
+ * copy at most maxlength bytes of whole utf8 characters to dest from the
+ * ucs2 string src.
+ *
+ * The return value is the number of characters copied, not including the
+ * final NUL character.
+ */
+unsigned long
+ucs2_as_utf8(u8 *dest, const ucs2_char_t *src, unsigned long maxlength)
+{
+ unsigned int i;
+ unsigned long j = 0;
+ unsigned long limit = ucs2_strnlen(src, maxlength);
+
+ for (i = 0; maxlength && i < limit; i++) {
+ u16 c = src[i];
+
+ if (c > 0x800) {
+ if (maxlength < 3)
+ break;
+ maxlength -= 3;
+ dest[j++] = 0xe0 | (c & 0xf000) >> 12;
+ dest[j++] = 0x80 | (c & 0x0fc0) >> 8;
+ dest[j++] = 0x80 | (c & 0x003f);
+ } else if (c > 0x80) {
+ if (maxlength < 2)
+ break;
+ maxlength -= 2;
+ dest[j++] = 0xc0 | (c & 0xfe0) >> 5;
+ dest[j++] = 0x80 | (c & 0x01f);
+ } else {
+ maxlength -= 1;
+ dest[j++] = c & 0x7f;
+ }
+ }
+ if (maxlength)
+ dest[j] = '\0';
+ return j;
+}
+EXPORT_SYMBOL(ucs2_as_utf8);