nuttx/libs/libc/stdio/lib_getdelim.c

/****************************************************************************
 * libs/libc/stdio/lib_libfgets.c
 *
 *   Copyright (C) 2007-2008, 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 <stdio.h>

#include "libc.h"

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

/****************************************************************************
 * Name: getdelim()
 *
 * Description:
 *   The getdelim() function will read from stream until it encounters a
 *   character matching the delimiter character.  The delimiter argument
 *   is an int, the value of which the application will ensure is a
 *   character representable as an unsigned char of equal value that
 *   terminates the read process. If the delimiter argument has any other
 *   value, the behavior is undefined.
 *
 *   The application will ensure that *lineptr is a valid argument that
 *   could be passed to the free() function.  If *n is non-zero, the
 *   application will ensure that *lineptr either points to an object of
 *   size at least *n bytes, or is a null pointer.
 *
 *   If *lineptr is a null pointer or if the object pointed to by
 *   *lineptr is of insufficient size, an object will be allocated as if
 *   by malloc() or the object will be reallocated as if by realloc(),
 *   respectively, such that the object is large enough to hold the
 *   characters to be written to it, including the terminating NUL, and
 *   *n will be set to the new size. If the object was allocated, or if
 *   the reallocation operation moved the object, *lineptr will be
 *   updated to point to the new object or new location.  The characters
 *   read, including any delimiter, will be stored in the object, and a
 *   terminating NUL added when the delimiter or end-of-file is encountered.
 *
 ****************************************************************************/

ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
                 FAR FILE *stream)
{
  FAR char *dest;
  size_t bufsize;
  ssize_t ncopied;
  int ch;
  int ret;

  /* Verify pointers */

  if (lineptr == NULL || n == NULL || stream == NULL)
    {
      ret = -EINVAL;
      goto errout;
    }

  /* Verify the buffer size */

  bufsize = *n;
  if (bufsize == 0)
    {
      return 0;
    }

  /* If *lineptr is a NULL pointer, then allocate *lineptr with size *n */

  dest = *lineptr;
  if (dest == NULL)
    {
      dest = (FAR char *)lib_malloc(bufsize);
      if (dest == NULL)
        {
          ret = -ENOMEM;
          goto errout;
        }

      *lineptr = dest;
    }

  /* *lineptr must be point to an object of size at least bufsize bytes.  If
   * the size of the buffer pointer to lineptr is less than bufsize, then
   * reallocate lineptr to bufsize.
   *
   * REVISIT:  How do you get the size of lineptr?  Isn't it just plain
   * uninitialized memory?
   */

  /* Transfer characters until either bufsize characters have been transfer
   * or until the delimiter is encountered.
   */

  ncopied = 0; /* No bytes have been transferred yet */
  bufsize--;   /* Reserve a byte for the NUL terminator */

  do
    {
      /* Get the next character and test for EOF */

      ch = fgetc(stream);
      if (ch == EOF)
        {
          break;
        }

      /* Save the character in the user buffer and increment the number of
       * bytes transferred.
       */

      *dest++ = ch;
      ncopied++;

      /* Terminate the loop when the delimiter is found or we have hit the
       * end of the buffer (reserving a byte for the NUL terminator)
       */
    }
  while (ch != delimiter && ncopied  < bufsize);

  /* Add a NUL terminator character (but don't report this in the number of
   * bytes transferred).
   */

  *dest = '\0';
  return ncopied;

errout:
#ifdef __KERNEL_
  return ret;
#else
  set_errno(-ret);
  return -1;
#endif
}

/****************************************************************************
 * Name: getdelim()
 *
 * Description:
 *   The getline() function will be equivalent to the getdelim() function
 *   with the delimiter character equal to the <newline> character.
 *
 *   NOTE: Because of this functional definition, getline() will not work
 *   with on systems where multiple characters are used to denote the end
 *   of line such a CR-LF sequences.  In that case, the CR will be
 *   transferred into the user buffer.
 *
 ****************************************************************************/

ssize_t getline(FAR char **lineptr, size_t *n, FAR FILE *stream)
{
  return getdelim(lineptr, n, '\n', stream);
}