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

/****************************************************************************
 * lib/stdio/lib_fgets.c
 *
 *   Copyright (C) 2007-2008, 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 <nuttx/config.h>

#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <debug.h>

/****************************************************************************
 * Definitions
 ****************************************************************************/
/* Some environments may return CR as end-of-line, others LF, and others
 * both.  The logic here assumes either but not both.
 */

#undef  CONFIG_EOL_IS_CR
#undef  CONFIG_EOL_IS_LF
#undef  CONFIG_EOL_IS_BOTH_CRLF
#define CONFIG_EOL_IS_EITHER_CRLF 1

/****************************************************************************
 * Private Type Declarations
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Private Data
 ****************************************************************************/

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

/****************************************************************************
 * Global Functions
 ****************************************************************************/

/****************************************************************************
 * Name: fgets
 *
 * Description:
 *   fgets() reads in at most one less than 'buflen' characters from stream
 *   and stores them into the buffer pointed to by 'buf'. Reading stops after
 *   an EOF or a newline.  If a newline is read, it is stored into the
 *   buffer.  A null terminator is stored after the last character in the
 *   buffer.
 *
 **************************************************************************/

char *fgets(FAR char *buf, int buflen, FILE *stream)
{
  int  nch = 0;

  /* Sanity checks */

  if (!stream || !buf || buflen < 1 || stream->fs_filedes < 0)
    {
      return NULL;
    }

  if (buflen < 2)
    {
      *buf = '\0';
      return buf;
    }

  /* Read characters until we have a full line. On each the loop we must
   * be assured that there are two free bytes in the line buffer:  One for
   * the next character and one for the null terminator.
   */

  for(;;)
    {
      /* Get the next character */

      int ch = fgetc(stream);

      /* Check for end-of-line.  This is tricky only in that some
       * environments may return CR as end-of-line, others LF, and
       * others both.
       */

#if  defined(CONFIG_EOL_IS_LF) || defined(CONFIG_EOL_IS_BOTH_CRLF)
      if (ch == '\n')
#elif defined(CONFIG_EOL_IS_CR)
      if (ch == '\r')
#elif CONFIG_EOL_IS_EITHER_CRLF
      if (ch == '\n' || ch == '\r')
#endif
        {
          /* The newline is stored in the buffer along with the null
           * terminator.
           */

          buf[nch++] = '\n';
          buf[nch]   = '\0';
          return buf;
        }

      /* Check for end-of-file */

      else if (ch == EOF)
        {
          /* End of file with no data? */

          if (!nch)
            {
              /* Yes.. return NULL as the end of file mark */

              return NULL;
            }
          else
            {
              /* Terminate the line */

              buf[nch]   = '\0';
              return buf;
            }
        }

      /* Otherwise, check if the character is printable and, if so, put the
       * character in the line buffer
       */

      else if (isprint(ch))
        {
          buf[nch++] = ch;

          /* Check if there is room for another character and the line's
           * null terminator.  If not then we have to end the line now.
           */

          if (nch + 1 >= buflen)
            {
              buf[nch] = '\0';
              return buf;
            }
        }
    }
}