iconv.c

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/* 
   Unix SMB/CIFS implementation.
   minimal iconv implementation
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Jelmer Vernooij 2002
   
   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 "lib/util/dlinklist.h"
#include "system/iconv.h"
#include "system/filesys.h"
#include "param/param.h"


/**
 * @file
 *
 * @brief Samba wrapper/stub for iconv character set conversion.
 *
 * iconv is the XPG2 interface for converting between character
 * encodings.  This file provides a Samba wrapper around it, and also
 * a simple reimplementation that is used if the system does not
 * implement iconv.
 *
 * Samba only works with encodings that are supersets of ASCII: ascii
 * characters like whitespace can be tested for directly, multibyte
 * sequences start with a byte with the high bit set, and strings are
 * terminated by a nul byte.
 *
 * Note that the only function provided by iconv is conversion between
 * characters.  It doesn't directly support operations like
 * uppercasing or comparison.  We have to convert to UTF-16LE and
 * compare there.
 *
 * @sa Samba Developers Guide
 **/

static size_t ascii_pull  (void *,const char **, size_t *, char **, size_t *);
static size_t ascii_push  (void *,const char **, size_t *, char **, size_t *);
static size_t utf8_pull   (void *,const char **, size_t *, char **, size_t *);
static size_t utf8_push   (void *,const char **, size_t *, char **, size_t *);
static size_t ucs2hex_pull(void *,const char **, size_t *, char **, size_t *);
static size_t ucs2hex_push(void *,const char **, size_t *, char **, size_t *);
static size_t iconv_copy  (void *,const char **, size_t *, char **, size_t *);
static size_t iconv_swab  (void *,const char **, size_t *, char **, size_t *);

static const struct charset_functions builtin_functions[] = {
	/* windows is closest to UTF-16 */
	{"UCS-2LE",  iconv_copy, iconv_copy},
	{"UTF-16LE",  iconv_copy, iconv_copy},
	{"UCS-2BE",  iconv_swab, iconv_swab},
	{"UTF-16BE",  iconv_swab, iconv_swab},

	/* we include the UTF-8 alias to cope with differing locale settings */
	{"UTF8",   utf8_pull,  utf8_push},
	{"UTF-8",   utf8_pull,  utf8_push},
	{"ASCII", ascii_pull, ascii_push},
	{"UCS2-HEX", ucs2hex_pull, ucs2hex_push}
};

static struct charset_functions *charsets = NULL;

bool charset_register_backend(const void *_funcs) 
{
	struct charset_functions *funcs = (struct charset_functions *)memdup(_funcs,sizeof(struct charset_functions));
	struct charset_functions *c;

	/* Check whether we already have this charset... */
	for (c = charsets; c != NULL; c = c->next) {
		if(!strcasecmp(c->name, funcs->name)) { 
			DEBUG(2, ("Duplicate charset %s, not registering\n", funcs->name));
			return false;
		}
	}

	funcs->next = funcs->prev = NULL;
	DLIST_ADD(charsets, funcs);
	return true;
}

#ifdef HAVE_NATIVE_ICONV
/* if there was an error then reset the internal state,
   this ensures that we don't have a shift state remaining for
   character sets like SJIS */
static size_t sys_iconv(void *cd, 
			const char **inbuf, size_t *inbytesleft,
			char **outbuf, size_t *outbytesleft)
{
	size_t ret = iconv((iconv_t)cd, 
			   discard_const_p(char *, inbuf), inbytesleft, 
			   outbuf, outbytesleft);
	if (ret == (size_t)-1) iconv(cd, NULL, NULL, NULL, NULL);
	return ret;
}
#endif

/**
 * This is a simple portable iconv() implementaion.
 *
 * It only knows about a very small number of character sets - just
 * enough that Samba works on systems that don't have iconv.
 **/
_PUBLIC_ size_t smb_iconv(smb_iconv_t cd, 
		 const char **inbuf, size_t *inbytesleft,
		 char **outbuf, size_t *outbytesleft)
{
	char cvtbuf[2048];
	size_t bufsize;

	/* in many cases we can go direct */
	if (cd->direct) {
		return cd->direct(cd->cd_direct, 
				  inbuf, inbytesleft, outbuf, outbytesleft);
	}


	/* otherwise we have to do it chunks at a time */
	while (*inbytesleft > 0) {
		char *bufp1 = cvtbuf;
		const char *bufp2 = cvtbuf;

		bufsize = sizeof(cvtbuf);
		
		if (cd->pull(cd->cd_pull, 
			     inbuf, inbytesleft, &bufp1, &bufsize) == -1
		    && errno != E2BIG) return -1;

		bufsize = sizeof(cvtbuf) - bufsize;

		if (cd->push(cd->cd_push, 
			     &bufp2, &bufsize, 
			     outbuf, outbytesleft) == -1) return -1;
	}

	return 0;
}

static bool is_utf16(const char *name)
{
	return strcasecmp(name, "UCS-2LE") == 0 ||
		strcasecmp(name, "UTF-16LE") == 0;
}



_PUBLIC_ smb_iconv_t smb_iconv_open_ex(TALLOC_CTX *mem_ctx, const char *tocode, 
			      const char *fromcode, bool native_iconv)
{
	smb_iconv_t ret;
	const struct charset_functions *from=NULL, *to=NULL;
	int i;

	ret = (smb_iconv_t)talloc_named(mem_ctx,
					sizeof(*ret), 
					"iconv(%s,%s)", tocode, fromcode);
	if (!ret) {
		errno = ENOMEM;
		return (smb_iconv_t)-1;
	}
	memset(ret, 0, sizeof(*ret));

	/* check for the simplest null conversion */
	if (strcmp(fromcode, tocode) == 0) {
		ret->direct = iconv_copy;
		return ret;
	}

	for (i=0;i<ARRAY_SIZE(builtin_functions);i++) {
		if (strcasecmp(fromcode, builtin_functions[i].name) == 0) {
			from = &builtin_functions[i];
		}
		if (strcasecmp(tocode, builtin_functions[i].name) == 0) {
			to = &builtin_functions[i];
		}
	}

	if (from == NULL) {
		for (from=charsets; from; from=from->next) {
			if (strcasecmp(from->name, fromcode) == 0) break;
		}
	}

	if (to == NULL) {
		for (to=charsets; to; to=to->next) {
			if (strcasecmp(to->name, tocode) == 0) break;
		}
	}

#ifdef HAVE_NATIVE_ICONV
	if ((!from || !to) && !native_iconv) {
		goto failed;
	}
	if (!from) {
		ret->pull = sys_iconv;
		ret->cd_pull = iconv_open("UTF-16LE", fromcode);
		if (ret->cd_pull == (iconv_t)-1)
			ret->cd_pull = iconv_open("UCS-2LE", fromcode);
		if (ret->cd_pull == (iconv_t)-1) goto failed;
	}

	if (!to) {
		ret->push = sys_iconv;
		ret->cd_push = iconv_open(tocode, "UTF-16LE");
		if (ret->cd_push == (iconv_t)-1)
			ret->cd_push = iconv_open(tocode, "UCS-2LE");
		if (ret->cd_push == (iconv_t)-1) goto failed;
	}
#else
	if (!from || !to) {
		goto failed;
	}
#endif

	/* check for conversion to/from ucs2 */
	if (is_utf16(fromcode) && to) {
		ret->direct = to->push;
		return ret;
	}
	if (is_utf16(tocode) && from) {
		ret->direct = from->pull;
		return ret;
	}

#ifdef HAVE_NATIVE_ICONV
	if (is_utf16(fromcode)) {
		ret->direct = sys_iconv;
		ret->cd_direct = ret->cd_push;
		ret->cd_push = NULL;
		return ret;
	}
	if (is_utf16(tocode)) {
		ret->direct = sys_iconv;
		ret->cd_direct = ret->cd_pull;
		ret->cd_pull = NULL;
		return ret;
	}
#endif

	/* the general case has to go via a buffer */
	if (!ret->pull) ret->pull = from->pull;
	if (!ret->push) ret->push = to->push;
	return ret;

failed:
	talloc_free(ret);
	errno = EINVAL;
	return (smb_iconv_t)-1;
}

/*
  simple iconv_open() wrapper
 */
_PUBLIC_ smb_iconv_t smb_iconv_open(const char *tocode, const char *fromcode)
{
	return smb_iconv_open_ex(NULL, tocode, fromcode, true);
}

/*
  simple iconv_close() wrapper
*/
_PUBLIC_ int smb_iconv_close(smb_iconv_t cd)
{
#ifdef HAVE_NATIVE_ICONV
	if (cd->cd_direct) iconv_close((iconv_t)cd->cd_direct);
	if (cd->cd_pull) iconv_close((iconv_t)cd->cd_pull);
	if (cd->cd_push) iconv_close((iconv_t)cd->cd_push);
#endif

	talloc_free(cd);
	return 0;
}


/**********************************************************************
 the following functions implement the builtin character sets in Samba
 and also the "test" character sets that are designed to test
 multi-byte character set support for english users
***********************************************************************/
static size_t ascii_pull(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	while (*inbytesleft >= 1 && *outbytesleft >= 2) {
		(*outbuf)[0] = (*inbuf)[0];
		(*outbuf)[1] = 0;
		(*inbytesleft)  -= 1;
		(*outbytesleft) -= 2;
		(*inbuf)  += 1;
		(*outbuf) += 2;
	}

	if (*inbytesleft > 0) {
		errno = E2BIG;
		return -1;
	}
	
	return 0;
}

static size_t ascii_push(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	int ir_count=0;

	while (*inbytesleft >= 2 && *outbytesleft >= 1) {
		(*outbuf)[0] = (*inbuf)[0] & 0x7F;
		if ((*inbuf)[1]) ir_count++;
		(*inbytesleft)  -= 2;
		(*outbytesleft) -= 1;
		(*inbuf)  += 2;
		(*outbuf) += 1;
	}

	if (*inbytesleft == 1) {
		errno = EINVAL;
		return -1;
	}

	if (*inbytesleft > 1) {
		errno = E2BIG;
		return -1;
	}
	
	return ir_count;
}


static size_t ucs2hex_pull(void *cd, const char **inbuf, size_t *inbytesleft,
			 char **outbuf, size_t *outbytesleft)
{
	while (*inbytesleft >= 1 && *outbytesleft >= 2) {
		uint_t v;

		if ((*inbuf)[0] != '@') {
			/* seven bit ascii case */
			(*outbuf)[0] = (*inbuf)[0];
			(*outbuf)[1] = 0;
			(*inbytesleft)  -= 1;
			(*outbytesleft) -= 2;
			(*inbuf)  += 1;
			(*outbuf) += 2;