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/*
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 * Copyright (c) 2006 Josef Cejka
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup libc
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 * @{
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 */
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/** @file
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 */
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#include <stdarg.h>
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#include <stdio.h>
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#include <string.h>
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#include <io/printf_core.h>
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struct vsnprintf_data {
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    size_t size;    /* total space for string */
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    size_t len; /* count of currently used characters */
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    char *string;   /* destination string */
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};
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/** Write string to given buffer.
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 * Write at most data->size characters including trailing zero. According to C99
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 * has snprintf to return number of characters that would have been written if
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 * enough space had been available. Hence the return value is not number of
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 * really printed characters but size of input string. Number of really used
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 * characters is stored in data->len.
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 *
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 * @param str       Source string to print.
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 * @param count     Size of the source string.
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 * @param data      Structure with destination string, counter of used space
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 *          and total string size.
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 * @return      Number of characters to print (not characters really
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 *          printed!)
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 */
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static int
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vsnprintf_write(const char *str, size_t count, struct vsnprintf_data *data)
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{
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    size_t i;
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    i = data->size - data->len;
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    if (i == 0) {
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        return count;
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    }
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    if (i == 1) {
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        /*
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         * We have only one free byte left in buffer => write there
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         * trailing zero.
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         */
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        data->string[data->size - 1] = 0;
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        data->len = data->size;
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        return count;
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    }
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    if (i <= count) {
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        /*
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         * We have not enought space for whole string with the trailing
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         * zero => print only a part of string.
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         */
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        memcpy((void *)(data->string + data->len), (void *)str, i - 1);
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        data->string[data->size - 1] = 0;
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        data->len = data->size;
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        return count;
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    }
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    /* Buffer is big enought to print whole string */
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    memcpy((void *)(data->string + data->len), (void *)str, count);
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    data->len += count;
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    /*
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     * Put trailing zero at end, but not count it into data->len so it could
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     * be rewritten next time.
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     */
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    data->string[data->len] = 0;
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    return count;  
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}
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/** Print formatted to the given buffer with limited size.
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 * @param str       Buffer.
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 * @param size      Bffer size.
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 * @param fmt       Format string.
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 * \see For more details about format string see printf_core.
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 */
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int vsnprintf(char *str, size_t size, const char *fmt, va_list ap)
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{
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    struct vsnprintf_data data = {size, 0, str};
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    struct printf_spec ps = {
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        (int(*)(void *, size_t, void *)) vsnprintf_write,
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        &data
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    };
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    /*
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     * Print 0 at end of string - fix the case that nothing will be printed.
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     */
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    if (size > 0)
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        str[0] = 0;
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    /* vsnprintf_write ensures that str will be terminated by zero. */
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    return printf_core(fmt, &ps, ap);
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}
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/** @}
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 */