1
2/* Copyright 1998 by the Massachusetts Institute of Technology.
3 *
4 * Permission to use, copy, modify, and distribute this
5 * software and its documentation for any purpose and without
6 * fee is hereby granted, provided that the above copyright
7 * notice appear in all copies and that both that copyright
8 * notice and this permission notice appear in supporting
9 * documentation, and that the name of M.I.T. not be used in
10 * advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission.
12 * M.I.T. makes no representations about the suitability of
13 * this software for any purpose.  It is provided "as is"
14 * without express or implied warranty.
15 */
16
17#include "ares_setup.h"
18#include <stdio.h>
19#include <stdlib.h>
20#include <string.h>
21#include "ares.h"
22#include "ares_nowarn.h"
23#include "ares_private.h"
24
25/* This is an internal function.  Its contract is to read a line from
26 * a file into a dynamically allocated buffer, zeroing the trailing
27 * newline if there is one.  The calling routine may call
28 * ares__read_line multiple times with the same buf and bufsize
29 * pointers; *buf will be reallocated and *bufsize adjusted as
30 * appropriate.  The initial value of *buf should be NULL.  After the
31 * calling routine is done reading lines, it should free *buf.
32 */
33int ares__read_line(FILE *fp, char **buf, size_t *bufsize)
34{
35  char *newbuf;
36  size_t offset = 0;
37  size_t len;
38
39  if (*buf == NULL)
40    {
41      *buf = malloc(128);
42      if (!*buf)
43        return ARES_ENOMEM;
44      *bufsize = 128;
45    }
46
47  for (;;)
48    {
49      int bytestoread = aresx_uztosi(*bufsize - offset);
50
51      if (!fgets(*buf + offset, bytestoread, fp))
52        return (offset != 0) ? 0 : (ferror(fp)) ? ARES_EFILE : ARES_EOF;
53      len = offset + strlen(*buf + offset);
54      if ((*buf)[len - 1] == '\n')
55        {
56          (*buf)[len - 1] = 0;
57          break;
58        }
59      offset = len;
60      if(len < *bufsize - 1)
61        continue;
62
63      /* Allocate more space. */
64      newbuf = realloc(*buf, *bufsize * 2);
65      if (!newbuf)
66        return ARES_ENOMEM;
67      *buf = newbuf;
68      *bufsize *= 2;
69    }
70  return ARES_SUCCESS;
71}
72