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    Subject[PATCH 4.4 055/342] lib/ucs2_string: Add ucs2 -> utf8 helper functions
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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);
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