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
19 #include "ares.h"
20 #include "ares_nowarn.h"
21 #include "ares_private.h"
22
23 /* This is an internal function. Its contract is to read a line from
24 * a file into a dynamically allocated buffer, zeroing the trailing
25 * newline if there is one. The calling routine may call
26 * ares__read_line multiple times with the same buf and bufsize
27 * pointers; *buf will be reallocated and *bufsize adjusted as
28 * appropriate. The initial value of *buf should be NULL. After the
29 * calling routine is done reading lines, it should free *buf.
30 */
ares__read_line(FILE * fp,char ** buf,size_t * bufsize)31 int ares__read_line(FILE *fp, char **buf, size_t *bufsize)
32 {
33 char *newbuf;
34 size_t offset = 0;
35 size_t len;
36
37 if (*buf == NULL)
38 {
39 *buf = ares_malloc(128);
40 if (!*buf)
41 return ARES_ENOMEM;
42 *bufsize = 128;
43 }
44
45 for (;;)
46 {
47 int bytestoread = aresx_uztosi(*bufsize - offset);
48
49 if (!fgets(*buf + offset, bytestoread, fp))
50 return (offset != 0) ? 0 : (ferror(fp)) ? ARES_EFILE : ARES_EOF;
51 len = offset + strlen(*buf + offset);
52 if ((*buf)[len - 1] == '\n')
53 {
54 (*buf)[len - 1] = 0;
55 break;
56 }
57 offset = len;
58 if(len < *bufsize - 1)
59 continue;
60
61 /* Allocate more space. */
62 newbuf = ares_realloc(*buf, *bufsize * 2);
63 if (!newbuf)
64 {
65 ares_free(*buf);
66 *buf = NULL;
67 return ARES_ENOMEM;
68 }
69 *buf = newbuf;
70 *bufsize *= 2;
71 }
72 return ARES_SUCCESS;
73 }
74