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/*

 * Copyright (c) 2006 Josef Cejka

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/** @addtogroup generic

 * @{

 */

/** @file

 */

#include <print.h>

#include <printf/printf_core.h>

#include <string.h>

#include <memstr.h>

typedef struct {

	size_t size;    /* Total size of the buffer (in bytes) */

	size_t len;     /* Number of already used bytes */

	char *dst;      /* Destination */

} vsnprintf_data_t;

/** Write UTF-8 string to given buffer.

 *

 * Write at most data->size plain characters including trailing zero.

 * According to C99, snprintf() has to return number of characters that

 * would have been written if enough space had been available. Hence

 * the return value is not the number of actually printed characters

 * but size of the input string.

 *

 * @param str  Source UTF-8 string to print.

 * @param size Number of plain characters in str.

 * @param data Structure describing destination string, counter

 *             of used space and total string size.

 *

 * @return Number of UTF-8 characters to print (not characters actually

 *         printed).

 *

 */

static int vsnprintf_write_utf8(const char *str, size_t size, vsnprintf_data_t *data)

{

	size_t left = data->size - data->len;

	if (left == 0)

		return ((int) size);

	if (left == 1) {

		/* We have only one free byte left in buffer

		 * -> store trailing zero

		 */

		data->dst[data->size - 1] = 0;

		data->len = data->size;

		return ((int) size);

	}

	if (left <= size) {

		/* We have not enought space for whole string

		 * with the trailing zero => print only a part

		 * of string

		 */

		index_t index = 0;

		while (index < size) {

			wchar_t uc = utf8_decode(str, &index, size);

			if (!utf8_encode(uc, data->dst, &data->len, data->size - 1))

				break;

		}

		/* Put trailing zero at end, but not count it

		 * into data->len so it could be rewritten next time

		 */

		data->dst[data->len] = 0;

		return ((int) size);

	}

	/* Buffer is big enought to print the whole string */

	memcpy((void *)(data->dst + data->len), (void *) str, size);

	data->len += size;

	/* Put trailing zero at end, but not count it

	 * into data->len so it could be rewritten next time

	 */

	data->dst[data->len] = 0;

	return ((int) size);

}

/** Write UTF-32 string to given buffer.

 *

 * Write at most data->size plain characters including trailing zero.

 * According to C99, snprintf() has to return number of characters that

 * would have been written if enough space had been available. Hence

 * the return value is not the number of actually printed characters

 * but size of the input string.

 *

 * @param str  Source UTF-32 string to print.

 * @param size Number of bytes in str.

 * @param data Structure describing destination string, counter

 *             of used space and total string size.

 *

 * @return Number of UTF-8 characters to print (not characters actually

 *         printed).

 *

 */

static int vsnprintf_write_utf32(const wchar_t *str, size_t size, vsnprintf_data_t *data)

{

	index_t index = 0;

	while (index < (size / sizeof(wchar_t))) {

		size_t left = data->size - data->len;

		if (left == 0)

			return ((int) size);

		if (left == 1) {

			/* We have only one free byte left in buffer

			 * -> store trailing zero

			 */

			data->dst[data->size - 1] = 0;

			data->len = data->size;

			return ((int) size);

		}

		if (!utf8_encode(str[index], data->dst, &data->len, data->size - 1))

			break;

		index++;

	}

	/* Put trailing zero at end, but not count it

	 * into data->len so it could be rewritten next time

	 */

	data->dst[data->len] = 0;

	return ((int) size);

}

int vsnprintf(char *str, size_t size, const char *fmt, va_list ap)

{

	vsnprintf_data_t data = {

		size,

		0,

		str

	};

	printf_spec_t ps = {

		(int(*) (const char *, size_t, void *)) vsnprintf_write_utf8,

		(int(*) (const wchar_t *, size_t, void *)) vsnprintf_write_utf32,

		&data

	};

	/* Print 0 at end of string - fix the case that nothing will be printed */

	if (size > 0)

		str[0] = 0;

	/* vsnprintf_write ensures that str will be terminated by zero. */

	return printf_core(fmt, &ps, ap);

}

/** @}

 */