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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