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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.

 */

#include <print.h>

#include <printf/printf_core.h>

#include <memstr.h>

struct vsnprintf_data {

    size_t size; /* total space for string */

    size_t len; /* count of currently used characters */

    char *string; /* destination string */

};

int vsnprintf_write(const char *str, size_t count, struct vsnprintf_data *data);

/** Write string to given buffer.

 * Write at most data->size 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

 * number of really printed characters but size of the input string. Number of really used characters

 * is stored in data->len.

 * @param str source string to print

 * @param count size of source string

 * @param data structure with destination string, counter of used space and total string size.

 * @return number of characters to print (not characters really printed!)

 */

int vsnprintf_write(const char *str, size_t count, struct vsnprintf_data *data)

{

    size_t i;

    i = data->size - data->len;

    if (i == 0) {

        return count;

    }

    if (i == 1) {

        /* We have only one free byte left in buffer => write there trailing zero */

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

        data->len = data->size;

        return count;

    }

    if (i <= count) {

        /* We have not enought space for whole string with the trailing zero => print only a part of string */

            memcpy((void *)(data->string + data->len), (void *)str, i - 1);

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

            data->len = data->size;

            return count;

    }

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

    memcpy((void *)(data->string + data->len), (void *)str, count);

    data->len += count;

    /* Put trailing zero at end, but not count it into data->len so it could be rewritten next time */

    data->string[data->len] = 0;

    return count;  

}

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

{

    struct vsnprintf_data data = {size, 0, str};

    struct printf_spec ps = {(int(*)(void *, size_t, void *))vsnprintf_write, &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);

}