px4-firmware/nuttx/lib/stdio/lib_rawoutstream.c

/****************************************************************************
 * lib/stdio/lib_rawoutstream.c
 *
 *   Copyright (C) 2007-2009, 2011-2012 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 <unistd.h>
#include <assert.h>
#include <errno.h>

#include "lib_internal.h"

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: rawoutstream_putc
 ****************************************************************************/

static void rawoutstream_putc(FAR struct lib_outstream_s *this, int ch)
{
  FAR struct lib_rawoutstream_s *rthis = (FAR struct lib_rawoutstream_s *)this;
  int nwritten;
  char buffer = ch;

  DEBUGASSERT(this && rthis->fd >= 0);

  /* Loop until the character is successfully transferred or until an
   * irrecoverable error occurs.
   */

  do
    {
      nwritten = write(rthis->fd, &buffer, 1);
      if (nwritten == 1)
        {
          this->nput++;
          return;
        }

      /* The only expected error is EINTR, meaning that the write operation
       * was awakened by a signal.  Zero would not be a valid return value
       * from write().
       */

      DEBUGASSERT(nwritten < 0);
    }
  while (get_errno() == EINTR);
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: lib_rawoutstream
 *
 * Description:
 *   Initializes a stream for use with a file descriptor.
 *
 * Input parameters:
 *   rawoutstream - User allocated, uninitialized instance of struct
 *                  lib_rawoutstream_s to be initialized.
 *   fd           - User provided file/socket descriptor (must have been opened
 *                  for write access).
 *
 * Returned Value:
 *   None (User allocated instance initialized).
 *
 ****************************************************************************/

void lib_rawoutstream(FAR struct lib_rawoutstream_s *rawoutstream, int fd)
{
  rawoutstream->public.put   = rawoutstream_putc;
#ifdef CONFIG_STDIO_LINEBUFFER
  rawoutstream->public.flush = lib_noflush;
#endif
  rawoutstream->public.nput  = 0;
  rawoutstream->fd           = fd;
}