text: /****************************************************************************
   * libs/libc/stdio/lib_vfscanf.c
   *
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.  The
   * ASF licenses this file to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance with the
   * License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations
   * under the License.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <stdio.h>
  
  #include <nuttx/streams.h>
  
  #include "libc.h"
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: vfscanf
   ****************************************************************************/
  
  int vfscanf(FAR FILE *stream, FAR const IPTR char *fmt, va_list ap)
  {
    struct lib_stdinstream_s stdinstream;
    int n = ERROR;
    int lastc;
  
    if (stream)
      {
        /* Wrap the stream in a stream object and let lib_vscanf do the work. */
  
        lib_stdinstream(&stdinstream, stream);
  
        /* Hold the stream semaphore throughout the lib_vscanf call so that
         * this thread can get its entire message out before being pre-empted
         * by the next thread.
         */
  
        lib_take_semaphore(stream);
  
        n = lib_vscanf(&stdinstream.public, &lastc, fmt, ap);
  
        /* The lib_vscanf function reads always one character more, this
         * character needs to be written back.
         */
  
        if (lastc != EOF)
          {
            ungetc(lastc, stream);
          }
  
        lib_give_semaphore(stream);
      }
  
    return n;
  }
  