/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * This program covers conversion from UTF-8, UCS-2, and, UCS-4 to UTF-7.
 * UTF-7 is described in RFC 2152.
 * We only support conversions between UCS-2/UCS-4/UTF-8 and UTF-7. No
 * other UCS formats are going to be supported unless there is a significant
 * reason.
 */


#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/isa_defs.h>
#include "ucs_to_utf7.h"


void *
_icv_open()
{
        utf7_state_t *cd = (utf7_state_t *)calloc(1, sizeof(utf7_state_t));

        if (cd == (utf7_state_t *)NULL) {
                errno = ENOMEM;
                return((void *)-1);
        }
#if defined(_LITTLE_ENDIAN)
        cd->little_endian = true;
#endif

        return((void *)cd);
}


void
_icv_close(utf7_state_t *cd)
{
        if (! cd)
                errno = EBADF;
        else
                free((void *)cd);
}


size_t
_icv_iconv(utf7_state_t *cd, char **inbuf, size_t *inbufleft, char **outbuf,
                size_t *outbufleft)
{
        size_t ret_val = 0;
        uchar_t *ib;
        uchar_t *ob;
        uchar_t *ibtail;
        uchar_t *obtail;
        uchar_t *ib_org;
        uint_t u4;
        uint_t u7;
        signed char sz;
        signed char new_bits_count;
        signed char new_remnant_count;
#if defined(UCS_2) || defined(UCS_4)
        register int i;
#endif

        if (! cd) {
                errno = EBADF;
                return((size_t)-1);
        }

        if (!inbuf || !(*inbuf)) {
                if (cd->in_the_middle_of_utf7_sequence) {
                        sz = (cd->remnant_count > 0) ? 2 : 1;

                        if ((! outbufleft) || *outbufleft < sz) {
                                errno = E2BIG;
                                return((size_t)-1);
                        }

                        if (cd->remnant_count > 0) {
                                /* Masking is needed. */
                                **outbuf = mb64[((cd->remnant <<
                                        (6 - cd->remnant_count)) & 0x003f)];
                                (*outbuf)++;
                        }

                        **outbuf = '-';
                        (*outbuf)++;
                        *outbufleft -= sz;
                }

                cd->remnant = 0;
                cd->remnant_count = 0;
                cd->in_the_middle_of_utf7_sequence = false;
#if defined(UCS_2) || defined(UCS_4)
                cd->bom_written = false;
#endif

                return((size_t)0);
        }

        ib = (uchar_t *)*inbuf;
        ob = (uchar_t *)*outbuf;
        ibtail = ib + *inbufleft;
        obtail = ob + *outbufleft;

#if defined(UCS_2) || defined(UCS_4)
        if (! cd->bom_written) {
                if ((ibtail - ib) < ICV_FETCH_UCS_SIZE) {
                        errno = EINVAL;
                        return((size_t)-1);
                }

                for (u4 = 0, i = 0; i < ICV_FETCH_UCS_SIZE; i++)
                        u4 = (u4 << 8) | ((uint_t)(*(ib + i)));

                if (u4 == ICV_BOM_IN_BIG_ENDIAN) {
                        ib += ICV_FETCH_UCS_SIZE;
                        cd->little_endian = false;
                } else if (u4 == ICV_BOM_IN_LITTLE_ENDIAN) {
                        ib += ICV_FETCH_UCS_SIZE;
                        cd->little_endian = true;
                }
        }
        cd->bom_written = true;
#endif

        while (ib < ibtail) {
#if defined(UTF_8)
                sz = number_of_bytes_in_utf8_char[*ib];
                if (sz == ICV_TYPE_ILLEGAL_CHAR) {
                        errno = EILSEQ;
                        ret_val = (size_t)-1;
                        break;
                }
#elif defined(UCS_2) || defined(UCS_4)
                sz = ICV_FETCH_UCS_SIZE;
#else
#error  "Fatal: One of UTF_8, UCS_2, or, UCS_4 is needed."
#endif

                if ((ibtail - ib) < sz) {
                        errno = EINVAL;
                        ret_val = (size_t)-1;
                        break;
                }

                ib_org = ib;
#if defined(UTF_8)
                u4 = *ib++ & masks_tbl[sz];
                for (; sz > 1; sz--) {
                        if (((uint_t)*ib) < 0x80) {
                                ib = ib_org;
                                errno = EILSEQ;
                                ret_val = (size_t)-1;
                                goto illegal_char_err;
                        }
                        u4 = (u4 << ICV_UTF8_BIT_SHIFT) |
                                (((uint_t)*ib) & ICV_UTF8_BIT_MASK);
                        ib++;
                }
#elif defined(UCS_2) || defined(UCS_4)
                u4 = 0;
                if (cd->little_endian) {
                        for (i = ICV_FETCH_UCS_SIZE - 1; i >= 0; i--)
                                u4 = (u4 << 8) | ((uint_t)(*(ib + i)));
                } else {
                        for (i = 0; i < ICV_FETCH_UCS_SIZE; i++)
                                u4 = (u4 << 8) | ((uint_t)(*(ib + i)));
                }
                ib += ICV_FETCH_UCS_SIZE;
#endif

                /* Check against known non-characters. */
#if defined(UTF_8)
                if ((u4 & ICV_UTF32_NONCHAR_mask) == ICV_UTF32_NONCHAR_fffe ||
                    (u4 & ICV_UTF32_NONCHAR_mask) == ICV_UTF32_NONCHAR_ffff ||
                    u4 > ICV_UTF32_LAST_VALID_CHAR ||
                    (u4 >= ICV_UTF32_SURROGATE_START_d800 &&
                    u4 <= ICV_UTF32_SURROGATE_END_dfff) ||
                    (u4 >= ICV_UTF32_ARABIC_NONCHAR_START_fdd0 &&
                    u4 <= ICV_UTF32_ARABIC_NONCHAR_END_fdef)) {
#elif defined(UCS_2)
                if (u4 >= ICV_UTF32_NONCHAR_fffe ||
                    (u4 >= ICV_UTF32_SURROGATE_START_d800 &&
                    u4 <= ICV_UTF32_SURROGATE_END_dfff) ||
                    (u4 >= ICV_UTF32_ARABIC_NONCHAR_START_fdd0 &&
                    u4 <= ICV_UTF32_ARABIC_NONCHAR_END_fdef)) {
#else
                if ((u4 & ICV_UTF32_NONCHAR_mask) == ICV_UTF32_NONCHAR_fffe ||
                    (u4 & ICV_UTF32_NONCHAR_mask) == ICV_UTF32_NONCHAR_ffff ||
                    u4 > ICV_UCS4_LAST_VALID_CHAR ||
                    (u4 >= ICV_UTF32_SURROGATE_START_d800 &&
                    u4 <= ICV_UTF32_SURROGATE_END_dfff) ||
                    (u4 >= ICV_UTF32_ARABIC_NONCHAR_START_fdd0 &&
                    u4 <= ICV_UTF32_ARABIC_NONCHAR_END_fdef)) {
#endif
                        ib = ib_org;
                        errno = EILSEQ;
                        ret_val = (size_t)-1;
                        goto illegal_char_err;
                }

#if defined(UCS_4) || defined(UTF_8)
                if (u4 > 0x00ffff) {
                        u4 = ICV_CHAR_UCS2_REPLACEMENT;
                        ret_val++;
                }
#endif

                /* Set D or Rule 3? */
                if ((u4 >= (uint_t)'A' && u4 <= (uint_t)'Z') ||
                    (u4 >= (uint_t)'a' && u4 <= (uint_t)'z') ||
                    (u4 >= (uint_t)'0' && u4 <= (uint_t)'9') ||
                    u4 == (uint_t)'\'' || u4 == (uint_t)'(' ||
                    u4 == (uint_t)')' ||
                    (u4 >= (uint_t)',' && u4 <= (uint_t)'/') || /* , - . / */
                    u4 == (uint_t)':' || u4 == (uint_t)'?' ||
                    u4 == (uint_t)' ' || u4 == (uint_t)'\t' ||
                    u4 == (uint_t)'\r' || u4 == (uint_t)'\n') {

                        u7 = 0;
                        sz = 1;
                        if (cd->in_the_middle_of_utf7_sequence) {
                                if (cd->remnant_count > 0) {
                                        sz++;
                                        u7 = cd->remnant <<
                                                (6 - cd->remnant_count);
                                }
                                if (u4 == (uint_t)'-' ||
                                    ICV_INRANGE_OF_MBASE64_ALPHABET(u4))
                                        sz++;
                        }

                        if ((obtail - ob) < sz) {
                                ib = ib_org;
                                errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }

                        if (cd->in_the_middle_of_utf7_sequence) {
                                /* Masking is needed. */
                                if (cd->remnant_count > 0)
                                        *ob++ = mb64[u7 & 0x003f];
                                if (u4 == (uint_t)'-' ||
                                    ICV_INRANGE_OF_MBASE64_ALPHABET(u4))
                                        *ob++ = '-';

                                cd->in_the_middle_of_utf7_sequence = false;
                                cd->remnant_count = 0;
                        }

                        *ob++ = (uchar_t)(u4 & 0x007f);

                } else {
/*
 * Any UCS-2 character sequences will yield:
 *
 * +-16 bits (UCS-2)-+  +-16 bits (UCS-2)-+  +-16 bits (UCS-2)-+
 * |                 |  |                 |  |                 |
 * xxxx xxxx xxxx xxxx  xxxx xxxx xxxx xxxx  xxxx xxxx xxxx xxxx
 * |     ||     | |      ||     | |     ||      | |     ||     |
 * +-----++-----+ +------++-----+ +-----++------+ +-----++-----+ MBase64 chars
 *                ^                      ^
 * initially,     |                      |
 *                four remnant bits,     |
 *                                       two remnant bits,
 *
 * and, then no remnant bit for three sequential UCS-2 characters,
 * respectively, and repeat these three UCS-2 character sequences. For the
 * first UCS-2 character in this sequence, there will be two MBase64
 * characters, and for the second and the third UCS-2 characters, there will be
 * three MBase64 characters.
 */
                        sz = (cd->remnant_count) ? 3 : 2;
                        if (! cd->in_the_middle_of_utf7_sequence)
                                sz++;

                        if ((obtail - ob) < sz) {
                                ib = ib_org;
                                errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }

                        if (! cd->in_the_middle_of_utf7_sequence) {
                                *ob++ = '+';
                                cd->in_the_middle_of_utf7_sequence = true;
                        }

                        if (cd->remnant_count) {
                                new_bits_count = 18 - cd->remnant_count;
                                new_remnant_count = 16 - new_bits_count;
                                u7 = (cd->remnant << new_bits_count) |
                                        (u4 >> new_remnant_count);
                                cd->remnant = u4 & 0x0003;
                                cd->remnant_count = new_remnant_count;

                                /* Masking is needed. */
                                *ob++ = mb64[(u7 >> 12) & 0x003f];
                                *ob++ = mb64[(u7 >> 6) & 0x003f];
                                *ob++ = mb64[u7 & 0x003f];
                        } else {
                                cd->remnant = u4 & 0x000f;
                                cd->remnant_count = 4;

                                /* Masking is needed. */
                                *ob++ = mb64[(u4 >> 10) & 0x003f];
                                *ob++ = mb64[(u4 >> 4) & 0x003f];
                        }
                }
        }

illegal_char_err:
        *inbuf = (char *)ib;
        *inbufleft = ibtail - ib;
        *outbuf = (char *)ob;
        *outbufleft = obtail - ob;

        return(ret_val);
}