/*
   * 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_uni2char_utf8(wchar_t uni,
  			     unsigned char *out,
  			     int boundlen)

  {

  	int u_len = 0;
  
  	if (boundlen <= 0)
  		return -ENAMETOOLONG;
  
  	if (uni < 0x80) {
  		out[u_len++] = (unsigned char)uni;
  	} else if (uni < 0x800) {
  		if (boundlen < 2)
  			return -ENAMETOOLONG;
  		out[u_len++] = (unsigned char)(0xc0 | (uni >> 6));
  		out[u_len++] = (unsigned char)(0x80 | (uni & 0x3f));
  	} else {
  		if (boundlen < 3)
  			return -ENAMETOOLONG;
  		out[u_len++] = (unsigned char)(0xe0 | (uni >> 12));
  		out[u_len++] = (unsigned char)(0x80 | ((uni >> 6) & 0x3f));
  		out[u_len++] = (unsigned char)(0x80 | (uni & 0x3f));

  	}

  	return u_len;

  }

  static int udf_char2uni_utf8(const unsigned char *in,
  			     int boundlen,
  			     wchar_t *uni)

  {

  	unsigned int utf_char;
  	unsigned char c;
  	int utf_cnt, u_len;

  	utf_char = 0;
  	utf_cnt = 0;
  	for (u_len = 0; u_len < boundlen;) {
  		c = in[u_len++];

  
  		/* Complete a multi-byte UTF-8 character */

  		if (utf_cnt) {

  			utf_char = (utf_char << 6) | (c & 0x3f);

  			if (--utf_cnt)
  				continue;

  		} else {

  			/* Check for a multi-byte UTF-8 character */

  			if (c & 0x80) {

  				/* Start a multi-byte UTF-8 character */

  				if ((c & 0xe0) == 0xc0) {
  					utf_char = c & 0x1f;

  					utf_cnt = 1;

  				} else if ((c & 0xf0) == 0xe0) {
  					utf_char = c & 0x0f;

  					utf_cnt = 2;

  				} else if ((c & 0xf8) == 0xf0) {
  					utf_char = c & 0x07;

  					utf_cnt = 3;

  				} else if ((c & 0xfc) == 0xf8) {
  					utf_char = c & 0x03;

  					utf_cnt = 4;

  				} else if ((c & 0xfe) == 0xfc) {
  					utf_char = c & 0x01;

  					utf_cnt = 5;

  				} else {

  					utf_cnt = -1;
  					break;

  				}

  				continue;

  			} else {

  				/* Single byte UTF-8 character (most common) */
  				utf_char = c;

  			}

  		}

  		*uni = utf_char;
  		break;

  	}

  	if (utf_cnt) {

  		*uni = '?';
  		return -EINVAL;

  	}

  	return u_len;

  }

  #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_name_conv_char(uint8_t *str_o, int str_o_max_len,
  			      int *str_o_idx,
  			      const uint8_t *str_i, int str_i_max_len,
  			      int *str_i_idx,
  			      int u_ch, int *needsCRC,
  			      int (*conv_f)(wchar_t, unsigned char *, int),
  			      int translate)
  {
  	uint32_t c;
  	int illChar = 0;
  	int len, gotch = 0;
  
  	for (; (!gotch) && (*str_i_idx < str_i_max_len); *str_i_idx += u_ch) {
  		if (*str_o_idx >= str_o_max_len) {
  			*needsCRC = 1;
  			return gotch;
  		}
  
  		/* Expand OSTA compressed Unicode to Unicode */
  		c = str_i[*str_i_idx];
  		if (u_ch > 1)
  			c = (c << 8) | str_i[*str_i_idx + 1];
  
  		if (translate && (c == '/' || c == 0))
  			illChar = 1;
  		else if (illChar)
  			break;
  		else
  			gotch = 1;
  	}
  	if (illChar) {
  		*needsCRC = 1;
  		c = ILLEGAL_CHAR_MARK;
  		gotch = 1;
  	}
  	if (gotch) {
  		len = conv_f(c, &str_o[*str_o_idx], str_o_max_len - *str_o_idx);
  		/* Valid character? */
  		if (len >= 0)
  			*str_o_idx += len;
  		else if (len == -ENAMETOOLONG) {
  			*needsCRC = 1;
  			gotch = 0;
  		} else {
  			str_o[(*str_o_idx)++] = '?';
  			*needsCRC = 1;
  		}
  	}
  	return gotch;
  }

  static int udf_name_from_CS0(uint8_t *str_o, int str_max_len,
  			     const uint8_t *ocu, int ocu_len,

  			     int (*conv_f)(wchar_t, unsigned char *, int),
  			     int translate)

  {

  	uint32_t c;

  	uint8_t cmp_id;

  	int idx, len;
  	int u_ch;
  	int needsCRC = 0;
  	int ext_i_len, ext_max_len;
  	int str_o_len = 0;	/* Length of resulting output */
  	int ext_o_len = 0;	/* Extension output length */
  	int ext_crc_len = 0;	/* Extension output length if used with CRC */
  	int i_ext = -1;		/* Extension position in input buffer */
  	int o_crc = 0;		/* Rightmost possible output pos for CRC+ext */
  	unsigned short valueCRC;
  	uint8_t ext[EXT_SIZE * NLS_MAX_CHARSET_SIZE + 1];
  	uint8_t crc[CRC_LEN];

  	if (str_max_len <= 0)
  		return 0;

  	if (ocu_len == 0) {

  		memset(str_o, 0, str_max_len);

  		return 0;
  	}

  	cmp_id = ocu[0];

  	if (cmp_id != 8 && cmp_id != 16) {

  		memset(str_o, 0, str_max_len);

  		pr_err("unknown compression code (%d)
  ", cmp_id);

  		return -EINVAL;

  	}

  	u_ch = cmp_id >> 3;

  	ocu++;
  	ocu_len--;

  	if (ocu_len % u_ch) {
  		pr_err("incorrect filename length (%d)
  ", ocu_len + 1);
  		return -EINVAL;
  	}
  
  	if (translate) {
  		/* Look for extension */
  		for (idx = ocu_len - u_ch, ext_i_len = 0;
  		     (idx >= 0) && (ext_i_len < EXT_SIZE);
  		     idx -= u_ch, ext_i_len++) {
  			c = ocu[idx];
  			if (u_ch > 1)
  				c = (c << 8) | ocu[idx + 1];
  
  			if (c == EXT_MARK) {
  				if (ext_i_len)
  					i_ext = idx;
  				break;
  			}
  		}
  		if (i_ext >= 0) {
  			/* Convert extension */
  			ext_max_len = min_t(int, sizeof(ext), str_max_len);
  			ext[ext_o_len++] = EXT_MARK;
  			idx = i_ext + u_ch;
  			while (udf_name_conv_char(ext, ext_max_len, &ext_o_len,
  						  ocu, ocu_len, &idx,
  						  u_ch, &needsCRC,
  						  conv_f, translate)) {
  				if ((ext_o_len + CRC_LEN) < str_max_len)
  					ext_crc_len = ext_o_len;
  			}
  		}
  	}
  
  	idx = 0;
  	while (1) {
  		if (translate && (idx == i_ext)) {
  			if (str_o_len > (str_max_len - ext_o_len))
  				needsCRC = 1;

  			break;

  		}
  
  		if (!udf_name_conv_char(str_o, str_max_len, &str_o_len,
  					ocu, ocu_len, &idx,
  					u_ch, &needsCRC, conv_f, translate))
  			break;
  
  		if (translate &&
  		    (str_o_len <= (str_max_len - ext_o_len - CRC_LEN)))
  			o_crc = str_o_len;
  	}
  
  	if (translate) {
  		if (str_o_len <= 2 && str_o[0] == '.' &&
  		    (str_o_len == 1 || str_o[1] == '.'))
  			needsCRC = 1;
  		if (needsCRC) {
  			str_o_len = o_crc;
  			valueCRC = crc_itu_t(0, ocu, ocu_len);
  			crc[0] = CRC_MARK;
  			crc[1] = hex_asc_upper_hi(valueCRC >> 8);
  			crc[2] = hex_asc_upper_lo(valueCRC >> 8);
  			crc[3] = hex_asc_upper_hi(valueCRC);
  			crc[4] = hex_asc_upper_lo(valueCRC);
  			len = min_t(int, CRC_LEN, str_max_len - str_o_len);
  			memcpy(&str_o[str_o_len], crc, len);
  			str_o_len += len;
  			ext_o_len = ext_crc_len;
  		}
  		if (ext_o_len > 0) {
  			memcpy(&str_o[str_o_len], ext, ext_o_len);
  			str_o_len += ext_o_len;
  		}

  	}

  	return str_o_len;

  }

  static int udf_name_to_CS0(uint8_t *ocu, int ocu_max_len,
  			   const uint8_t *str_i, int str_len,

  			   int (*conv_f)(const unsigned char *, int, wchar_t *))

  {

  	int i, len;
  	unsigned int max_val;
  	wchar_t uni_char;

  	int u_len, u_ch;

  	if (ocu_max_len <= 0)
  		return 0;
  
  	memset(ocu, 0, ocu_max_len);

  	ocu[0] = 8;

  	max_val = 0xff;

  	u_ch = 1;

  try_again:

  	u_len = 1;
  	for (i = 0; i < str_len; i++) {

  		/* Name didn't fit? */

  		if (u_len + u_ch > ocu_max_len)

  			return 0;

  		len = conv_f(&str_i[i], str_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 = 0xffff;
  			ocu[0] = 0x10;

  			u_ch = 2;

  			goto try_again;
  		}

  		if (max_val == 0xffff)

  			ocu[u_len++] = (uint8_t)(uni_char >> 8);
  		ocu[u_len++] = (uint8_t)(uni_char & 0xff);

  		i += len - 1;
  	}

  	return u_len;

  }

  int udf_dstrCS0toUTF8(uint8_t *utf_o, int o_len,
  		      const uint8_t *ocu_i, int i_len)

  {

  	int s_len = 0;
  
  	if (i_len > 0) {
  		s_len = ocu_i[i_len - 1];
  		if (s_len >= i_len) {
  			pr_err("incorrect dstring lengths (%d/%d)
  ",
  			       s_len, i_len);
  			return -EINVAL;
  		}
  	}
  
  	return udf_name_from_CS0(utf_o, o_len, ocu_i, s_len,

  				 udf_uni2char_utf8, 0);

  }

  int udf_get_filename(struct super_block *sb, const uint8_t *sname, int slen,

  		     uint8_t *dname, int dlen)

  {

  	int (*conv_f)(wchar_t, unsigned char *, int);

  	int ret;

  	if (!slen)
  		return -EIO;

  	if (dlen <= 0)
  		return 0;

  	if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {

  		conv_f = udf_uni2char_utf8;

  	} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {

  		conv_f = UDF_SB(sb)->s_nls_map->uni2char;

  	} else

  		BUG();

  	ret = udf_name_from_CS0(dname, dlen, sname, slen, conv_f, 1);

  	/* Zero length filename isn't valid... */
  	if (ret == 0)
  		ret = -EINVAL;

  	return ret;

  }

  int udf_put_filename(struct super_block *sb, const uint8_t *sname, int slen,
  		     uint8_t *dname, int dlen)

  {

  	int (*conv_f)(const unsigned char *, int, wchar_t *);

  	if (UDF_QUERY_FLAG(sb, UDF_FLAG_UTF8)) {

  		conv_f = udf_char2uni_utf8;

  	} else if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP)) {

  		conv_f = UDF_SB(sb)->s_nls_map->char2uni;

  	} else

  		BUG();

  	return udf_name_to_CS0(dname, dlen, sname, slen, conv_f);

  }