/*-
 * Copyright (c) 2010 Marcel Moolenaar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#ifndef _KERNEL
#include <errno.h>
#endif
#ifdef _STANDALONE
#include <stand.h>
#else
#ifdef _KERNEL
#include <sys/malloc.h>
#include <sys/systm.h>
#else
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#endif
#include <sys/efi.h>
#include <machine/efi.h>
#endif

#include "efichar.h"

int
ucs2len(const efi_char *str)
{
        int i;

        i = 0;
        while (*str++)
                i++;
        return (i);
}

/*
 * If nm were converted to utf8, what what would strlen
 * return on the resulting string?
 */
static size_t
utf8_len_of_ucs2(const efi_char *nm)
{
        size_t len;
        efi_char c;

        len = 0;
        while (*nm) {
                c = *nm++;
                if (c > 0x7ff)
                        len += 3;
                else if (c > 0x7f)
                        len += 2;
                else
                        len++;
        }

        return (len);
}

int
ucs2_to_utf8(const efi_char *nm, char **name)
{
        size_t len, sz;
        efi_char c;
        char *cp;
        int freeit = *name == NULL;

        sz = utf8_len_of_ucs2(nm) + 1;
        len = 0;
        if (*name != NULL)
                cp = *name;
        else
                cp = *name = EFICHAR_MALLOC(sz);
        if (*name == NULL)
                return (ENOMEM);

        while (*nm) {
                c = *nm++;
                if (c > 0x7ff) {
                        if (len++ < sz)
                                *cp++ = (char)(0xE0 | (c >> 12));
                        if (len++ < sz)
                                *cp++ = (char)(0x80 | ((c >> 6) & 0x3f));
                        if (len++ < sz)
                                *cp++ = (char)(0x80 | (c & 0x3f));
                } else if (c > 0x7f) {
                        if (len++ < sz)
                                *cp++ = (char)(0xC0 | ((c >> 6) & 0x1f));
                        if (len++ < sz)
                                *cp++ = (char)(0x80 | (c & 0x3f));
                } else {
                        if (len++ < sz)
                                *cp++ = (char)(c & 0x7f);
                }
        }

        if (len >= sz) {
                /* Absent bugs, we'll never return EOVERFLOW */
                if (freeit) {
                        EFICHAR_FREE(*name);
                        *name = NULL;
                }
                return (EOVERFLOW);
        }
        *cp++ = '\0';

        return (0);
}

int
utf8_to_ucs2(const char *name, efi_char **nmp, size_t *len)
{
        efi_char *nm;
        size_t sz;
        uint32_t ucs4;
        int c, bytes;
        int freeit = *nmp == NULL;

        sz = strlen(name) * 2 + 2;
        if (*nmp == NULL)
                *nmp = EFICHAR_MALLOC(sz);
        if (*nmp == NULL)
                return (ENOMEM);
        nm = *nmp;
        *len = sz;

        ucs4 = 0;
        bytes = 0;
        while (sz > 1 && *name != '\0') {
                c = *name++;
                /*
                 * Conditionalize on the two major character types:
                 * initial and followup characters.
                 */
                if ((c & 0xc0) != 0x80) {
                        /* Initial characters. */
                        if (bytes != 0)
                                goto ilseq;
                        if ((c & 0xf8) == 0xf0) {
                                ucs4 = c & 0x07;
                                bytes = 3;
                        } else if ((c & 0xf0) == 0xe0) {
                                ucs4 = c & 0x0f;
                                bytes = 2;
                        } else if ((c & 0xe0) == 0xc0) {
                                ucs4 = c & 0x1f;
                                bytes = 1;
                        } else {
                                ucs4 = c & 0x7f;
                                bytes = 0;
                        }
                } else {
                        /* Followup characters. */
                        if (bytes > 0) {
                                ucs4 = (ucs4 << 6) + (c & 0x3f);
                                bytes--;
                        } else if (bytes == 0)
                                goto ilseq;
                }
                if (bytes == 0) {
                        if (ucs4 > 0xffff)
                                goto ilseq;
                        *nm++ = (efi_char)ucs4;
                        sz -= 2;
                }
        }
        if (sz < 2) {
                if (freeit) {
                        EFICHAR_FREE(nm);
                        *nmp = NULL;
                }
                return (EDOOFUS);
        }
        sz -= 2;
        *nm = 0;
        *len -= sz;
        return (0);
ilseq:
        if (freeit) {
                EFICHAR_FREE(nm);
                *nmp = NULL;
        }
        return (EILSEQ);
}