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getline.c

/* getline.c -- Replacement for GNU C library function getline

   Copyright (C) 1993, 1996, 1997, 1998, 2000, 2003 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 2, 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, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* Written by Jan Brittenson, bson@gnu.ai.mit.edu.  */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include "getline.h"

/* The `getdelim' function is only declared if the following symbol
   is defined.  */
#ifndef _GNU_SOURCE
# define _GNU_SOURCE 1
#endif

#include <stdio.h>
#include <sys/types.h>

#if defined __GNU_LIBRARY__ && HAVE_GETDELIM

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

#else /* ! have getdelim */

# if STDC_HEADERS
#  include <stdlib.h>
# else
char *malloc (), *realloc ();
# endif

#include "unlocked-io.h"

/* Always add at least this many bytes when extending the buffer.  */
#define MIN_CHUNK 64

/* Read up to (and including) a delimiter DELIM1 from STREAM into *LINEPTR
   + OFFSET (and NUL-terminate it).  If DELIM2 is non-zero, then read up
   and including the first occurrence of DELIM1 or DELIM2.  *LINEPTR is
   a pointer returned from malloc (or NULL), pointing to *N characters of
   space.  It is realloc'd as necessary.  Return the number of characters
   read (not including the NUL terminator), or -1 on error or EOF.  */

static int
getdelim2 (char **lineptr, size_t *n, FILE *stream, int delim1, int delim2,
         size_t offset)
{
  size_t nchars_avail;        /* Allocated but unused chars in *LINEPTR.  */
  char *read_pos;       /* Where we're reading into *LINEPTR. */
  int ret;

  if (!lineptr || !n || !stream)
    return -1;

  if (!*lineptr)
    {
      *n = MIN_CHUNK;
      *lineptr = malloc (*n);
      if (!*lineptr)
      return -1;
    }

  if (*n < offset)
    return -1;

  nchars_avail = *n - offset;
  read_pos = *lineptr + offset;

  for (;;)
    {
      register int c = getc (stream);

      /* We always want at least one char left in the buffer, since we
       always (unless we get an error while reading the first char)
       NUL-terminate the line buffer.  */

      if (nchars_avail < 2)
      {
        if (*n > MIN_CHUNK)
          *n *= 2;
        else
          *n += MIN_CHUNK;

        nchars_avail = *n + *lineptr - read_pos;
        *lineptr = realloc (*lineptr, *n);
        if (!*lineptr)
          return -1;
        read_pos = *n - nchars_avail + *lineptr;
      }

      if (c == EOF || ferror (stream))
      {
        /* Return partial line, if any.  */
        if (read_pos == *lineptr)
          return -1;
        else
          break;
      }

      *read_pos++ = c;
      nchars_avail--;

      if (c == delim1 || (delim2 && c == delim2))
      /* Return the line.  */
      break;
    }

  /* Done - NUL terminate and return the number of chars read.  */
  *read_pos = '\0';

  ret = read_pos - (*lineptr + offset);
  return ret;
}


int
getline (char **lineptr, size_t *n, FILE *stream)
{
  return getdelim2 (lineptr, n, stream, '\n', 0, 0);
}

int
getdelim (char **lineptr, size_t *n, int delimiter, FILE *stream)
{
  return getdelim2 (lineptr, n, stream, delimiter, 0, 0);
}
#endif

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