/*
 * unicode.c
 *
 * PURPOSE
 *      Routines for converting between UTF-8 and OSTA Compressed Unicode.
 *      Also handles filename mangling
 *
 * DESCRIPTION
 *      OSTA Compressed Unicode is explained in the OSTA UDF specification.
 *              http://www.osta.org/
 *      UTF-8 is explained in the IETF RFC XXXX.
 *              ftp://ftp.internic.net/rfc/rfcxxxx.txt
 *
 * COPYRIGHT
 *      This file is distributed under the terms of the GNU General Public
 *      License (GPL). Copies of the GPL can be obtained from:
 *              ftp://prep.ai.mit.edu/pub/gnu/GPL
 *      Each contributing author retains all rights to their own work.
 */

#include "udfdecl.h"

#include <linux/kernel.h>
#include <linux/string.h>       /* for memset */
#include <linux/nls.h>
#include <linux/crc-itu-t.h>
#include <linux/slab.h>

#include "udf_sb.h"

static int udf_translate_to_linux(uint8_t *, int, uint8_t *, int, uint8_t *,
                                  int);

static int udf_char_to_ustr(struct ustr *dest, const uint8_t *src, int strlen)
{
        if ((!dest) || (!src) || (!strlen) || (strlen > UDF_NAME_LEN - 2))
                return 0;

        memset(dest, 0, sizeof(struct ustr));
        memcpy(dest->u_name, src, strlen);
        dest->u_cmpID = 0x08;
        dest->u_len = strlen;

        return strlen;
}

/*
 * udf_build_ustr
 */
int udf_build_ustr(struct ustr *dest, dstring *ptr, int size)
{
        int usesize;

        if (!dest || !ptr || !size)
                return -1;
        BUG_ON(size < 2);

        usesize = min_t(size_t, ptr[size - 1], sizeof(dest->u_name));
        usesize = min(usesize, size - 2);
        dest->u_cmpID = ptr[0];
        dest->u_len = usesize;
        memcpy(dest->u_name, ptr + 1, usesize);
        memset(dest->u_name + usesize, 0, sizeof(dest->u_name) - usesize);

        return 0;
}

/*
 * udf_build_ustr_exact
 */
static int udf_build_ustr_exact(struct ustr *dest, dstring *ptr, int exactsize)
{
        if ((!dest) || (!ptr) || (!exactsize))
                return -1;

        memset(dest, 0, sizeof(struct ustr));
        dest->u_cmpID = ptr[0];
        dest->u_len = exactsize - 1;
        memcpy(dest->u_name, ptr + 1, exactsize - 1);

        return 0;
}

/*
 * udf_ocu_to_utf8
 *
 * PURPOSE
 *      Convert OSTA Compressed Unicode to the UTF-8 equivalent.
 *
 * PRE-CONDITIONS
 *      utf                     Pointer to UTF-8 output buffer.
 *      ocu                     Pointer to OSTA Compressed Unicode input buffer
 *                              of size UDF_NAME_LEN bytes.
 *                              both of type "struct ustr *"
 *
 * POST-CONDITIONS
 *      <return>                Zero on success.
 *
 * HISTORY
 *      November 12, 1997 - Andrew E. Mileski
 *      Written, tested, and released.
 */
int udf_CS0toUTF8(struct ustr *utf_o, const struct ustr *ocu_i)
{
        const uint8_t *ocu;
        uint8_t cmp_id, ocu_len;
        int i;

        ocu_len = ocu_i->u_len;
        if (ocu_len == 0) {
                memset(utf_o, 0, sizeof(struct ustr));
                return 0;
        }

        cmp_id = ocu_i->u_cmpID;
        if (cmp_id != 8 && cmp_id != 16) {
                memset(utf_o, 0, sizeof(struct ustr));
                pr_err("unknown compression code (%d) stri=%s\n",
                       cmp_id, ocu_i->u_name);
                return 0;
        }

        ocu = ocu_i->u_name;
        utf_o->u_len = 0;
        for (i = 0; (i < ocu_len) && (utf_o->u_len <= (UDF_NAME_LEN - 3));) {

                /* Expand OSTA compressed Unicode to Unicode */
                uint32_t c = ocu[i++];
                if (cmp_id == 16)
                        c = (c << 8) | ocu[i++];

                /* Compress Unicode to UTF-8 */
                if (c < 0x80U)
                        utf_o->u_name[utf_o->u_len++] = (uint8_t)c;
                else if (c < 0x800U) {
                        utf_o->u_name[utf_o->u_len++] =
                                                (uint8_t)(0xc0 | (c >> 6));
                        utf_o->u_name[utf_o->u_len++] =
                                                (uint8_t)(0x80 | (c & 0x3f));
                } else {
                        utf_o->u_name[utf_o->u_len++] =
                                                (uint8_t)(0xe0 | (c >> 12));
                        utf_o->u_name[utf_o->u_len++] =
                                                (uint8_t)(0x80 |
                                                          ((c >> 6) & 0x3f));
                        utf_o->u_name[utf_o->u_len++] =
                                                (uint8_t)(0x80 | (c & 0x3f));
                }
        }
        utf_o->u_cmpID = 8;

        return utf_o->u_len;
}

/*
 *
 * udf_utf8_to_ocu
 *
 * PURPOSE
 *      Convert UTF-8 to the OSTA Compressed Unicode equivalent.
 *
 * DESCRIPTION
 *      This routine is only called by udf_lookup().
 *
 * PRE-CONDITIONS
 *      ocu                     Pointer to OSTA Compressed Unicode output
 *                              buffer of size UDF_NAME_LEN bytes.
 *      utf                     Pointer to UTF-8 input buffer.
 *      utf_len                 Length of UTF-8 input buffer in bytes.
 *
 * POST-CONDITIONS
 *      <return>                Zero on success.
 *
 * HISTORY
 *      November 12, 1997 - Andrew E. Mileski
 *      Written, tested, and released.
 */
static int udf_UTF8toCS0(dstring *ocu, struct ustr *utf, int length)
{
        unsigned c, i, max_val, utf_char;
        int utf_cnt, u_len;

        memset(ocu, 0, sizeof(dstring) * length);
        ocu[0] = 8;
        max_val = 0xffU;

try_again:
        u_len = 0U;
        utf_char = 0U;
        utf_cnt = 0U;
        for (i = 0U; i < utf->u_len; i++) {
                c = (uint8_t)utf->u_name[i];

                /* Complete a multi-byte UTF-8 character */
                if (utf_cnt) {
                        utf_char = (utf_char << 6) | (c & 0x3fU);
                        if (--utf_cnt)
                                continue;
                } else {
                        /* Check for a multi-byte UTF-8 character */
                        if (c & 0x80U) {
                                /* Start a multi-byte UTF-8 character */
                                if ((c & 0xe0U) == 0xc0U) {
                                        utf_char = c & 0x1fU;
                                        utf_cnt = 1;
                                } else if ((c & 0xf0U) == 0xe0U) {
                                        utf_char = c & 0x0fU;
                                        utf_cnt = 2;
                                } else if ((c & 0xf8U) == 0xf0U) {
                                        utf_char = c & 0x07U;
                                        utf_cnt = 3;
                                } else if ((c & 0xfcU) == 0xf8U) {
                                        utf_char = c & 0x03U;
                                        utf_cnt = 4;
                                } else if ((c & 0xfeU) == 0xfcU) {
                                        utf_char = c & 0x01U;
                                        utf_cnt = 5;
                                } else {
                                        goto error_out;
                                }
                                continue;
                        } else {
                                /* Single byte UTF-8 character (most common) */
                                utf_char = c;
                        }
                }

                /* Choose no compression if necessary */
                if (utf_char > max_val) {
                        if (max_val == 0xffU) {
                                max_val = 0xffffU;
                                ocu[0] = (uint8_t)0x10U;
                                goto try_again;
                        }
                        goto error_out;
                }

                if (max_val == 0xffffU)
                        ocu[++u_len] = (uint8_t)(utf_char >> 8);
                ocu[++u_len] = (uint8_t)(utf_char & 0xffU);
        }

        if (utf_cnt) {
error_out:
                ocu[++u_len] = '?';
                printk(KERN_DEBUG pr_fmt("bad UTF-8 character\n"));
        }

        ocu[length - 1] = (uint8_t)u_len + 1;

        return u_len + 1;
}

static int udf_CS0toNLS(struct nls_table *nls, struct ustr *utf_o,
                        const struct ustr *ocu_i)
{
        const uint8_t *ocu;
        uint8_t cmp_id, ocu_len;
        int i, len;


        ocu_len = ocu_i->u_len;
        if (ocu_len == 0) {
                memset(utf_o, 0, sizeof(struct ustr));
                return 0;
        }

        cmp_id = ocu_i->u_cmpID;
        if (cmp_id != 8 && cmp_id != 16) {
                memset(utf_o, 0, sizeof(struct ustr));
                pr_err("unknown compression code (%d) stri=%s\n",
                       cmp_id, ocu_i->u_name);
                return 0;
        }

        ocu = ocu_i->u_name;
        utf_o->u_len = 0;
        for (i = 0; (i < ocu_len) && (utf_o->u_len <= (UDF_NAME_LEN - 3));) {
                /* Expand OSTA compressed Unicode to Unicode */
                uint32_t c = ocu[i++];
                if (cmp_id == 16)
                        c = (c << 8) | ocu[i++];

                len = nls->uni2char(c, &utf_o->u_name[utf_o->u_len],
                                    UDF_NAME_LEN - utf_o->u_len);
                /* Valid character? */
                if (len >= 0)
                        utf_o->u_len += len;
                else
                        utf_o->u_name[utf_o->u_len++] = '?';
        }
        utf_o->u_cmpID = 8;

        return utf_o->u_len;
}

static int udf_NLStoCS0(struct nls_table *nls, dstring *ocu, struct ustr *uni,
                        int length)
{
        int len;
        unsigned i, max_val;
        uint16_t uni_char;
        int u_len;

        memset(ocu, 0, sizeof(dstring) * length);
        ocu[0] = 8;
        max_val = 0xffU;

try_again:
        u_len = 0U;
        for (i = 0U; i < uni->u_len; i++) {
                len = nls->char2uni(&uni->u_name[i], uni->u_len - i, &uni_char);
                if (!len)
                        continue;
                /* Invalid character, deal with it */
                if (len < 0) {
                        len = 1;
                        uni_char = '?';
                }

                if (uni_char > max_val) {
                        max_val = 0xffffU;
                        ocu[0] = (uint8_t)0x10U;
                        goto try_again;
                }

                if (max_val == 0xffffU)
                        ocu[++u_len] = (uint8_t)(uni_char >> 8);
                ocu[++u_len] = (uint8_t)(uni_char & 0xffU);
                i += len - 1;
        }

        ocu[length - 1] = (uint8_t)u_len + 1;
        return u_len + 1;
}

int udf_get_filename(struct super_block *sb, uint8_t *sname, int slen,
                     uint8_t *dname, int dlen)
{
        struct ustr *filename, *unifilename;
        int len = 0;

        filename = kmalloc(sizeof(struct ustr), GFP_NOFS);
        if (!filename)
                return 0;

        unifilename = kmalloc(sizeof(struct ustr), GFP_NOFS);
        if (!unifilename)
                goto out1;

        if (udf_build_ustr_exact(unifilename, sname, slen))
                goto out2;

        if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
                if (!udf_CS0toUTF8(filename, unifilename)) {
                        udf_debug("Failed in udf_get_filename: sname = %s\n",
                                  sname);
                        goto out2;
                }
        } else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
                if (!udf_CS0toNLS(UDF_SB(sb)->s_nls_map, filename,
                                  unifilename)) {
                        udf_debug("Failed in udf_get_filename: sname = %s\n",
                                  sname);
                        goto out2;
                }
        } else
                goto out2;

        len = udf_translate_to_linux(dname, dlen,
                                     filename->u_name, filename->u_len,
                                     unifilename->u_name, unifilename->u_len);
out2:
        kfree(unifilename);
out1:
        kfree(filename);
        return len;
}

int udf_put_filename(struct super_block *sb, const uint8_t *sname,
                     uint8_t *dname, int flen)
{
        struct ustr unifilename;
        int namelen;

        if (!udf_char_to_ustr(&unifilename, sname, flen))
                return 0;

        if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {
                namelen = udf_UTF8toCS0(dname, &unifilename, UDF_NAME_LEN);
                if (!namelen)
                        return 0;
        } else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {
                namelen = udf_NLStoCS0(UDF_SB(sb)->s_nls_map, dname,
                                        &unifilename, UDF_NAME_LEN);
                if (!namelen)
                        return 0;
        } else
                return 0;

        return namelen;
}

#define ILLEGAL_CHAR_MARK       '_'
#define EXT_MARK                '.'
#define CRC_MARK                '#'
#define EXT_SIZE                5
/* Number of chars we need to store generated CRC to make filename unique */
#define CRC_LEN                 5

static int udf_translate_to_linux(uint8_t *newName, int newLen,
                                  uint8_t *udfName, int udfLen,
                                  uint8_t *fidName, int fidNameLen)
{
        int index, newIndex = 0, needsCRC = 0;
        int extIndex = 0, newExtIndex = 0, hasExt = 0;
        unsigned short valueCRC;
        uint8_t curr;

        if (udfName[0] == '.' &&
            (udfLen == 1 || (udfLen == 2 && udfName[1] == '.'))) {
                needsCRC = 1;
                newIndex = udfLen;
                memcpy(newName, udfName, udfLen);
        } else {
                for (index = 0; index < udfLen; index++) {
                        curr = udfName[index];
                        if (curr == '/' || curr == 0) {
                                needsCRC = 1;
                                curr = ILLEGAL_CHAR_MARK;
                                while (index + 1 < udfLen &&
                                                (udfName[index + 1] == '/' ||
                                                 udfName[index + 1] == 0))
                                        index++;
                        }
                        if (curr == EXT_MARK &&
                                        (udfLen - index - 1) <= EXT_SIZE) {
                                if (udfLen == index + 1)
                                        hasExt = 0;
                                else {
                                        hasExt = 1;
                                        extIndex = index;
                                        newExtIndex = newIndex;
                                }
                        }
                        if (newIndex < newLen)
                                newName[newIndex++] = curr;
                        else
                                needsCRC = 1;
                }
        }
        if (needsCRC) {
                uint8_t ext[EXT_SIZE];
                int localExtIndex = 0;

                if (hasExt) {
                        int maxFilenameLen;
                        for (index = 0;
                             index < EXT_SIZE && extIndex + index + 1 < udfLen;
                             index++) {
                                curr = udfName[extIndex + index + 1];

                                if (curr == '/' || curr == 0) {
                                        needsCRC = 1;
                                        curr = ILLEGAL_CHAR_MARK;
                                        while (extIndex + index + 2 < udfLen &&
                                              (index + 1 < EXT_SIZE &&
                                                (udfName[extIndex + index + 2] == '/' ||
                                                 udfName[extIndex + index + 2] == 0)))
                                                index++;
                                }
                                ext[localExtIndex++] = curr;
                        }
                        maxFilenameLen = newLen - CRC_LEN - localExtIndex;
                        if (newIndex > maxFilenameLen)
                                newIndex = maxFilenameLen;
                        else
                                newIndex = newExtIndex;
                } else if (newIndex > newLen - CRC_LEN)
                        newIndex = newLen - CRC_LEN;
                newName[newIndex++] = CRC_MARK;
                valueCRC = crc_itu_t(0, fidName, fidNameLen);
                newName[newIndex++] = hex_asc_upper_hi(valueCRC >> 8);
                newName[newIndex++] = hex_asc_upper_lo(valueCRC >> 8);
                newName[newIndex++] = hex_asc_upper_hi(valueCRC);
                newName[newIndex++] = hex_asc_upper_lo(valueCRC);

                if (hasExt) {
                        newName[newIndex++] = EXT_MARK;
                        for (index = 0; index < localExtIndex; index++)
                                newName[newIndex++] = ext[index];
                }
        }

        return newIndex;
}