nuttx/libc/stdio/lib_snprintf.c

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/****************************************************************************
* libc/stdio/lib_snprintf.c
*
* Copyright (C) 2007-2009, 2011, 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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
* COPYRIGHT OWNER OR CONTRIBUTORS 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdio.h>
#include "lib_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Type Declarations
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Public Constant Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Constant Data
****************************************************************************/
/****************************************************************************
* Private Variables
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* sprintf
****************************************************************************/
int snprintf(FAR char *buf, size_t size, const char *format, ...)
{
union
{
struct lib_outstream_s nulloutstream;
struct lib_memoutstream_s memoutstream;
} u;
FAR struct lib_outstream_s *stream;
va_list ap;
int n;
/* "If the value of [size] is zero on a call to snprintf(), nothing shall
* be written, the number of bytes that would have been written had [size]
* been sufficiently large excluding the terminating null shall be returned,
* and [buf] may be a null pointer." -- opengroup.org
*/
if (size > 0)
{
/* Initialize a memory stream to write to the buffer */
lib_memoutstream(&u.memoutstream, buf, size);
stream = &u.memoutstream.public;
}
else
{
/* Use a null stream to get the size of the buffer */
lib_nulloutstream(&u.nulloutstream);
stream = &u.nulloutstream;
}
/* Then let lib_vsprintf do the real work */
va_start(ap, format);
n = lib_vsprintf(stream, format, ap);
va_end(ap);
return n;
}