/* Provenance: openssl/openssl bmp_to_utf8 (fixed).
 * repo: openssl/openssl
 * commit: 4191043c36f1a50c717a2d0075fc6f3b9bc0afc5
 * parent: 7565bb46fa2979511cb27aad1c2bd6b80adf7352
 * commit_url: https://github.com/openssl/openssl/commit/4191043c36f1a50c717a2d0075fc6f3b9bc0afc5
 * cve: CVE-2025-69419
 * license: Apache-2.0
 * function: bmp_to_utf8
 * relpath: crypto/pkcs12/p12_utl.c
 */

static int bmp_to_utf8(char *str, const unsigned char *utf16, int len)
{
    unsigned long utf32chr;

    if (len == 0)
        return 0;

    if (len < 2)
        return -1;

    /* pull UTF-16 character in big-endian order */
    utf32chr = (utf16[0] << 8) | utf16[1];

    if (utf32chr >= 0xD800 && utf32chr < 0xE000) { /* two chars */
        unsigned int lo;

        if (len < 4)
            return -1;

        utf32chr -= 0xD800;
        utf32chr <<= 10;
        lo = (utf16[2] << 8) | utf16[3];
        if (lo < 0xDC00 || lo >= 0xE000)
            return -1;
        utf32chr |= lo - 0xDC00;
        utf32chr += 0x10000;
    }

    return UTF8_putc((unsigned char *)str, 4, utf32chr);
}