78 lines
2.5 KiB
C
78 lines
2.5 KiB
C
/****************************************************************************
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* libs/libc/stdio/lib_vsnprintf.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <stdio.h>
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#include "libc.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: vsnprintf
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****************************************************************************/
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int vsnprintf(FAR char *buf, size_t size, FAR const IPTR char *format,
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va_list ap)
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{
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union
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{
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struct lib_outstream_s nulloutstream;
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struct lib_memoutstream_s memoutstream;
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} u;
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FAR struct lib_outstream_s *stream;
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int n;
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/* "If the value of [size] is zero on a call to vsnprintf(), nothing shall
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* be written, the number of bytes that would have been written had [size]
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* been sufficiently large excluding the terminating null shall be
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* returned, and [buf] may be a null pointer." -- opengroup.org
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*/
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if (size > 0)
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{
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/* Initialize a memory stream to write to the buffer */
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lib_memoutstream(&u.memoutstream, buf, size);
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stream = &u.memoutstream.common;
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}
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else
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{
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/* Use a null stream to get the size of the buffer */
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lib_nulloutstream(&u.nulloutstream);
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stream = &u.nulloutstream;
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}
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/* Then let lib_vsprintf do the real work */
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n = lib_vsprintf(stream, format, ap);
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return n;
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}
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