/* Copyright 1998 by the Massachusetts Institute of Technology.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

/* This file is part of liblocker. It implements various utility
   routines. */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "locker.h"
#include "locker_private.h"

static const char rcsid[] = "$Id: util.c,v 1.1 1999-02-26 19:04:54 danw Exp $";

/* This is an internal function.  Its contract is to read a line from a
 * file into a dynamically allocated buffer, zeroing the trailing newline
 * if there is one.  The calling routine may call locker__read_line multiple
 * times with the same buf and bufsize pointers; *buf will be reallocated
 * and *bufsize adjusted as appropriate.  The initial value of *buf
 * should be NULL.  After the calling routine is done reading lines, it
 * should free *buf.  This function returns 0 if a line was successfully
 * read, 1 if the file ended, and -1 if there was an I/O error or if it
 * ran out of memory.
 */

int locker__read_line(FILE *fp, char **buf, int *bufsize)
{
  char *newbuf;
  int offset = 0, len;

  if (*buf == NULL)
    {
      *buf = malloc(128);
      if (!*buf)
	return -1;
      *bufsize = 128;
    }

  while (1)
    {
      if (!fgets(*buf + offset, *bufsize - offset, fp))
	return (offset != 0) ? 0 : (ferror(fp)) ? -1 : 1;
      len = offset + strlen(*buf + offset);
      if ((*buf)[len - 1] == '\n')
	{
	  (*buf)[len - 1] = 0;
	  return 0;
	}
      offset = len;

      /* Allocate more space. */
      newbuf = realloc(*buf, *bufsize * 2);
      if (!newbuf)
	return -1;
      *buf = newbuf;
      *bufsize *= 2;
    }
}