/* linebuffer.c -- read arbitrarily long lines

   Copyright (C) 1986, 1991, 1998-1999, 2001, 2003-2004, 2006-2007, 2009-2018

   Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Richard Stallman. */

#include <config.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include "linebuffer.h"

#include "xalloc.h"

#if USE_UNLOCKED_IO

# include "unlocked-io.h"

#endif

/* Initialize linebuffer LINEBUFFER for use. */

void

initbuffer (struct linebuffer *linebuffer)

{

  memset (linebuffer, 0, sizeof *linebuffer);

}

struct linebuffer *

readlinebuffer (struct linebuffer *linebuffer, FILE *stream)

{

  return readlinebuffer_delim (linebuffer, stream, '\n');

}

/* Read an arbitrarily long line of text from STREAM into LINEBUFFER.

   Consider lines to be terminated by DELIMITER.

   Keep the delimiter; append DELIMITER if it's the last line of a file

   that ends in a character other than DELIMITER.  Do not NUL-terminate.

   Therefore the stream can contain NUL bytes, and the length

   (including the delimiter) is returned in linebuffer->length.

   Return NULL when stream is empty.  Return NULL and set errno upon

   error; callers can distinguish this case from the empty case by

   invoking ferror (stream).

   Otherwise, return LINEBUFFER.  */

struct linebuffer *

readlinebuffer_delim (struct linebuffer *linebuffer, FILE *stream,

                      char delimiter)

{

  int c;

  char *buffer = linebuffer->buffer;

  char *p = linebuffer->buffer;

  char *end = buffer + linebuffer->size; /* Sentinel. */

  if (feof (stream))

    return NULL;

  do

    {

      c = getc (stream);

      if (c == EOF)

        {

          if (p == buffer || ferror (stream))

            return NULL;

          if (p[-1] == delimiter)

            break;

          c = delimiter;

        }

      if (p == end)

        {

          size_t oldsize = linebuffer->size;

          buffer = x2realloc (buffer, &linebuffer->size);

          p = buffer + oldsize;

          linebuffer->buffer = buffer;

          end = buffer + linebuffer->size;

        }

      *p++ = c;

    }

  while (c != delimiter);

  linebuffer->length = p - buffer;

  return linebuffer;

}

/* Free the buffer that was allocated for linebuffer LINEBUFFER.  */

void

freebuffer (struct linebuffer *linebuffer)

{

  free (linebuffer->buffer);

}