/*
 * 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"

#define SURROGATE_MASK 0xfffff800
#define SURROGATE_PAIR 0x0000d800

static int udf_uni2char_utf8(wchar_t uni,
			     unsigned char *out,
			     int boundlen)
{
	int u_len = 0;

	if (boundlen <= 0)
		return -ENAMETOOLONG;

	if ((uni & SURROGATE_MASK) == SURROGATE_PAIR)
		return -EINVAL;

	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)\n", cmp_id);
		return -EINVAL;
	}
	u_ch = cmp_id >> 3;

	ocu++;
	ocu_len--;

	if (ocu_len % u_ch) {
		pr_err("incorrect filename length (%d)\n", 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;
}

/*
 * Convert CS0 dstring to output charset. Warning: This function may truncate
 * input string if it is too long as it is used for informational strings only
 * and it is better to truncate the string than to refuse mounting a media.
 */
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_warn("incorrect dstring lengths (%d/%d),"
				" truncating\n", s_len, i_len);
			s_len = i_len - 1;
			/* 2-byte encoding? Need to round properly... */
			if (ocu_i[0] == 16)
				s_len -= (s_len - 1) & 2;
		}
	}

	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);
}