/* 
   Unix SMB/CIFS implementation.
   Character set conversion Extensions
   Copyright (C) Igor Vergeichik <iverg@mail.ru> 2001
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Simo Sorce 2001
   Copyright (C) Jelmer Vernooij 2007
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/
#include "includes.h"
#include "system/iconv.h"

/**
 * @file
 *
 * @brief Character-set conversion routines built on our iconv.
 * 
 * @note Samba's internal character set (at least in the 3.0 series)
 * is always the same as the one for the Unix filesystem.  It is
 * <b>not</b> necessarily UTF-8 and may be different on machines that
 * need i18n filenames to be compatible with Unix software.  It does
 * have to be a superset of ASCII.  All multibyte sequences must start
 * with a byte with the high bit set.
 *
 * @sa lib/iconv.c
 */

struct smb_iconv_convenience {
	TALLOC_CTX *child_ctx;
	const char *unix_charset;
	const char *dos_charset;
	bool native_iconv;
	smb_iconv_t conv_handles[NUM_CHARSETS][NUM_CHARSETS];
};


/**
 * Return the name of a charset to give to iconv().
 **/
static const char *charset_name(struct smb_iconv_convenience *ic, charset_t ch)
{
	switch (ch) {
	case CH_UTF16: return "UTF-16LE";
	case CH_UNIX: return ic->unix_charset;
	case CH_DOS: return ic->dos_charset;
	case CH_UTF8: return "UTF8";
	case CH_UTF16BE: return "UTF-16BE";
	case CH_UTF16MUNGED: return "UTF16_MUNGED";
	default:
	return "ASCII";
	}
}

/**
 re-initialize iconv conversion descriptors
**/
static int close_iconv_convenience(struct smb_iconv_convenience *data)
{
	unsigned c1, c2;
	for (c1=0;c1<NUM_CHARSETS;c1++) {
		for (c2=0;c2<NUM_CHARSETS;c2++) {
			if (data->conv_handles[c1][c2] != NULL) {
				if (data->conv_handles[c1][c2] != (smb_iconv_t)-1) {
					smb_iconv_close(data->conv_handles[c1][c2]);
				}
				data->conv_handles[c1][c2] = NULL;
			}
		}
	}

	return 0;
}

/*
  the old_ic is passed in here as the smb_iconv_convenience structure
  is used as a global pointer in some places (eg. python modules). We
  don't want to invalidate those global pointers, but we do want to
  update them with the right charset information when loadparm
  runs. To do that we need to re-use the structure pointer, but
  re-fill the elements in the structure with the updated values
 */
_PUBLIC_ struct smb_iconv_convenience *smb_iconv_convenience_reinit(TALLOC_CTX *mem_ctx,
								    const char *dos_charset,
								    const char *unix_charset,
								    bool native_iconv,
								    struct smb_iconv_convenience *old_ic)
{
	struct smb_iconv_convenience *ret;

	if (old_ic != NULL) {
		ret = old_ic;
		close_iconv_convenience(ret);
		talloc_free(ret->child_ctx);
		ZERO_STRUCTP(ret);
	} else {
		ret = talloc_zero(mem_ctx, struct smb_iconv_convenience);
	}
	if (ret == NULL) {
		return NULL;
	}

	/* we use a child context to allow us to free all ptrs without
	   freeing the structure itself */
	ret->child_ctx = talloc_new(ret);
	if (ret->child_ctx == NULL) {
		return NULL;
	}

	talloc_set_destructor(ret, close_iconv_convenience);

	ret->dos_charset = talloc_strdup(ret->child_ctx, dos_charset);
	ret->unix_charset = talloc_strdup(ret->child_ctx, unix_charset);
	ret->native_iconv = native_iconv;

	return ret;
}

/*
  on-demand initialisation of conversion handles
*/
static smb_iconv_t get_conv_handle(struct smb_iconv_convenience *ic,
				   charset_t from, charset_t to)
{
	const char *n1, *n2;
	static bool initialised;

	if (initialised == false) {
		initialised = true;
		
#ifdef LC_ALL
		/* we set back the locale to C to get ASCII-compatible
		   toupper/lower functions.  For now we do not need
		   any other POSIX localisations anyway. When we
		   should really need localized string functions one
		   day we need to write our own ascii_tolower etc.
		*/
		setlocale(LC_ALL, "C");
#endif
	}

	if (ic->conv_handles[from][to]) {
		return ic->conv_handles[from][to];
	}

	n1 = charset_name(ic, from);
	n2 = charset_name(ic, to);

	ic->conv_handles[from][to] = smb_iconv_open_ex(ic, n2, n1, 
						       ic->native_iconv);
	
	if (ic->conv_handles[from][to] == (smb_iconv_t)-1) {
		if ((from == CH_DOS || to == CH_DOS) &&
		    strcasecmp(charset_name(ic, CH_DOS), "ASCII") != 0) {
			DEBUG(0,("dos charset '%s' unavailable - using ASCII\n",
				 charset_name(ic, CH_DOS)));
			ic->dos_charset = "ASCII";

			n1 = charset_name(ic, from);
			n2 = charset_name(ic, to);
			
			ic->conv_handles[from][to] = 
				smb_iconv_open_ex(ic, n2, n1, ic->native_iconv);
		}
	}

	return ic->conv_handles[from][to];
}

/**
 * Convert string from one encoding to another, making error checking etc
 *
 * @param mem_ctx Memory context
 * @param cd Iconv handle
 * @param src pointer to source string (multibyte or singlebyte)
 * @param srclen length of the source string in bytes
 * @param dest pointer to destination string (multibyte or singlebyte)
 * @param destlen maximal length allowed for string
 * @returns the number of bytes occupied in the destination
 **/
_PUBLIC_ ssize_t iconv_talloc(TALLOC_CTX *ctx, 
				       smb_iconv_t cd,
				       void const *src, size_t srclen, 
				       void *dst)
{
	size_t i_len, o_len, destlen;
	void **dest = (void **)dst;
	size_t retval;
	const char *inbuf = (const char *)src;
	char *outbuf, *ob;

	*dest = NULL;

	/* it is _very_ rare that a conversion increases the size by
	   more than 3x */
	destlen = srclen;
	outbuf = NULL;
convert:
	destlen = 2 + (destlen*3);
	ob = talloc_realloc(ctx, outbuf, char, destlen);
	if (!ob) {
		DEBUG(0, ("iconv_talloc: realloc failed!\n"));
		talloc_free(outbuf);
		return (size_t)-1;
	} else {
		outbuf = ob;
	}

	/* we give iconv 2 less bytes to allow us to terminate at the
	   end */
	i_len = srclen;
	o_len = destlen-2;
	retval = smb_iconv(cd,
			   &inbuf, &i_len,
			   &outbuf, &o_len);
	if(retval == (size_t)-1) 		{
	    	const char *reason="unknown error";
		switch(errno) {
			case EINVAL:
				reason="Incomplete multibyte sequence";
				break;
			case E2BIG:
				goto convert;		
			case EILSEQ:
				reason="Illegal multibyte sequence";
				break;
		}
		DEBUG(0,("Conversion error: %s - ",reason));
		dump_data(0, (const uint8_t *) inbuf, i_len);
		talloc_free(ob);
		return (size_t)-1;
	}
	
	destlen = (destlen-2) - o_len;

	/* guarantee null termination in all charsets */
	SSVAL(ob, destlen, 0);

	*dest = ob;

	return destlen;

}

/**
 * Convert string from one encoding to another, making error checking etc
 *
 * @param src pointer to source string (multibyte or singlebyte)
 * @param srclen length of the source string in bytes
 * @param dest pointer to destination string (multibyte or singlebyte)
 * @param destlen maximal length allowed for string
 * @returns the number of bytes occupied in the destination
 **/
_PUBLIC_ bool convert_string_convenience(struct smb_iconv_convenience *ic,
				charset_t from, charset_t to,
				void const *src, size_t srclen, 
				void *dest, size_t destlen, size_t *converted_size,
				bool allow_badcharcnv)
{
	size_t i_len, o_len;
	size_t retval;
	const char* inbuf = (const char*)src;
	char* outbuf = (char*)dest;
	smb_iconv_t descriptor;

	if (allow_badcharcnv) {
		/* Not implemented yet */
		return false;
	}

	if (srclen == (size_t)-1)
		srclen = strlen(inbuf)+1;

	descriptor = get_conv_handle(ic, from, to);

	if (descriptor == (smb_iconv_t)-1 || descriptor == (smb_iconv_t)0) {
		/* conversion not supported, use as is */
		size_t len = MIN(srclen,destlen);
		memcpy(dest,src,len);
		*converted_size = len;
		return true;
	}

	i_len=srclen;
	o_len=destlen;
	retval = smb_iconv(descriptor,  &inbuf, &i_len, &outbuf, &o_len);
	if(retval==(size_t)-1) {
	    	const char *reason;
		switch(errno) {
			case EINVAL:
				reason="Incomplete multibyte sequence";
				return false;
			case E2BIG:
				reason="No more room"; 
				if (from == CH_UNIX) {
					DEBUG(0,("E2BIG: convert_string(%s,%s): srclen=%d destlen=%d - '%s'\n",
						 charset_name(ic, from), charset_name(ic, to),
						 (int)srclen, (int)destlen, 
						 (const char *)src));
				} else {
					DEBUG(0,("E2BIG: convert_string(%s,%s): srclen=%d destlen=%d\n",
						 charset_name(ic, from), charset_name(ic, to),
						 (int)srclen, (int)destlen));
				}
			       return false;
			case EILSEQ:
			       reason="Illegal multibyte sequence";
			       return false;
		}
		/* smb_panic(reason); */
	}
	if (converted_size != NULL)
		*converted_size = destlen-o_len;
	return true;
}
	
/**
 * Convert between character sets, allocating a new buffer using talloc for the result.
 *
 * @param srclen length of source buffer.
 * @param dest always set at least to NULL
 * @note -1 is not accepted for srclen.
 *
 * @returns Size in bytes of the converted string; or -1 in case of error.
 **/

_PUBLIC_ bool convert_string_talloc_convenience(TALLOC_CTX *ctx, 
				       struct smb_iconv_convenience *ic, 
				       charset_t from, charset_t to, 
				       void const *src, size_t srclen, 
				       void *dst, size_t *converted_size, 
					   bool allow_badcharcnv)
{
	void **dest = (void **)dst;
	smb_iconv_t descriptor;
	ssize_t ret;

	if (allow_badcharcnv)
		return false; /* Not implemented yet */

	*dest = NULL;

	if (src == NULL || srclen == (size_t)-1 || srclen == 0)
		return false;

	descriptor = get_conv_handle(ic, from, to);

	if (descriptor == (smb_iconv_t)-1 || descriptor == (smb_iconv_t)0) {
		/* conversion not supported, return -1*/
		DEBUG(3, ("convert_string_talloc: conversion from %s to %s not supported!\n",
			  charset_name(ic, from), 
			  charset_name(ic, to)));
		return false;
	}

	ret = iconv_talloc(ctx, descriptor, src, srclen, dest);
	if (ret == -1)
		return false;
	if (converted_size != NULL)
		*converted_size = ret;
	return true;
}

/*
  return the unicode codepoint for the next multi-byte CH_UNIX character
  in the string

  also return the number of bytes consumed (which tells the caller
  how many bytes to skip to get to the next CH_UNIX character)

  return INVALID_CODEPOINT if the next character cannot be converted
*/
_PUBLIC_ codepoint_t next_codepoint_convenience(struct smb_iconv_convenience *ic, 
				    const char *str, size_t *size)
{
	/* it cannot occupy more than 4 bytes in UTF16 format */
	uint8_t buf[4];
	smb_iconv_t descriptor;
	size_t ilen_orig;
	size_t ilen;
	size_t olen;
	char *outbuf;

	if ((str[0] & 0x80) == 0) {
		*size = 1;
		return (codepoint_t)str[0];
	}

	/* we assume that no multi-byte character can take
	   more than 5 bytes. This is OK as we only
	   support codepoints up to 1M */
	ilen_orig = strnlen(str, 5);
	ilen = ilen_orig;

	descriptor = get_conv_handle(ic, CH_UNIX, CH_UTF16);
	if (descriptor == (smb_iconv_t)-1) {
		*size = 1;
		return INVALID_CODEPOINT;
	}

	/* this looks a little strange, but it is needed to cope
	   with codepoints above 64k */
	olen = 2;
	outbuf = (char *)buf;
	smb_iconv(descriptor, &str, &ilen, &outbuf, &olen);
	if (olen == 2) {
		olen = 4;
		outbuf = (char *)buf;
		smb_iconv(descriptor,  &str, &ilen, &outbuf, &olen);
		if (olen == 4) {
			/* we didn't convert any bytes */
			*size = 1;
			return INVALID_CODEPOINT;
		}
		olen = 4 - olen;
	} else {
		olen = 2 - olen;
	}

	*size = ilen_orig - ilen;

	if (olen == 2) {
		return (codepoint_t)SVAL(buf, 0);
	}
	if (olen == 4) {
		/* decode a 4 byte UTF16 character manually */
		return (codepoint_t)0x10000 + 
			(buf[2] | ((buf[3] & 0x3)<<8) | 
			 (buf[0]<<10) | ((buf[1] & 0x3)<<18));
	}

	/* no other length is valid */
	return INVALID_CODEPOINT;
}

/*
  push a single codepoint into a CH_UNIX string the target string must
  be able to hold the full character, which is guaranteed if it is at
  least 5 bytes in size. The caller may pass less than 5 bytes if they
  are sure the character will fit (for example, you can assume that
  uppercase/lowercase of a character will not add more than 1 byte)

  return the number of bytes occupied by the CH_UNIX character, or
  -1 on failure
*/
_PUBLIC_ ssize_t push_codepoint_convenience(struct smb_iconv_convenience *ic, 
				char *str, codepoint_t c)
{
	smb_iconv_t descriptor;
	uint8_t buf[4];
	size_t ilen, olen;
	const char *inbuf;
	
	if (c < 128) {
		*str = c;
		return 1;
	}

	descriptor = get_conv_handle(ic, 
				     CH_UTF16, CH_UNIX);
	if (descriptor == (smb_iconv_t)-1) {
		return -1;
	}

	if (c < 0x10000) {
		ilen = 2;
		olen = 5;
		inbuf = (char *)buf;
		SSVAL(buf, 0, c);
		smb_iconv(descriptor, &inbuf, &ilen, &str, &olen);
		if (ilen != 0) {
			return -1;
		}
		return 5 - olen;
	}

	c -= 0x10000;

	buf[0] = (c>>10) & 0xFF;
	buf[1] = (c>>18) | 0xd8;
	buf[2] = c & 0xFF;
	buf[3] = ((c>>8) & 0x3) | 0xdc;

	ilen = 4;
	olen = 5;
	inbuf = (char *)buf;

	smb_iconv(descriptor, &inbuf, &ilen, &str, &olen);
	if (ilen != 0) {
		return -1;
	}
	return 5 - olen;
}