nss/bug-erange.c

   1 /* Test case for gethostbyname_r bug when buffer expansion required.  */
   2
   3 #include <netdb.h>
   4 #include <arpa/inet.h>
   5 #include <errno.h>
   6 #include <string.h>
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9
  10 int
  11 main (void)
  12 {
  13   const char *host = "www.gnu.org";
  14
  15   /* This code approximates the example code in the library manual.  */
  16
  17   struct hostent hostbuf, *hp;
  18   size_t hstbuflen;
  19   char *tmphstbuf;
  20   int res;
  21   int herr;
  22
  23   hstbuflen = 16;               /* Make it way small to ensure ERANGE.  */
  24   /* Allocate buffer, remember to free it to avoid memory leakage.  */
  25   tmphstbuf = malloc (hstbuflen);
  26
  27   while ((res = gethostbyname_r (host, &hostbuf, tmphstbuf, hstbuflen,
  28                                  &hp, &herr)) == ERANGE)
  29     {
  30       /* Enlarge the buffer.  */
  31       hstbuflen *= 2;
  32       tmphstbuf = realloc (tmphstbuf, hstbuflen);
  33     }
  34
  35   if (res != 0 || hp == NULL)
  36     {
  37       printf ("gethostbyname_r failed: %s (errno: %m)\n", strerror (res));
  38       return 1;
  39     }
  40
  41   printf ("Got: %s %s\n", hp->h_name,
  42           inet_ntoa (*(struct in_addr *) hp->h_addr));
  43   return 0;
  44 }