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glibc/nss/bug-erange.c
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/* Test case for gethostbyname_r bug when buffer expansion required. */ | |
#include <netdb.h> | |
#include <arpa/inet.h> | |
#include <errno.h> | |
#include <string.h> | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <unistd.h> | |
int | |
main (void) | |
{ | |
const char *host = "www.gnu.org"; | |
/* This code approximates the example code in the library manual. */ | |
struct hostent hostbuf, *hp; | |
size_t hstbuflen; | |
char *tmphstbuf; | |
int res; | |
int herr; | |
hstbuflen = 16; /* Make it way small to ensure ERANGE. */ | |
/* Allocate buffer, remember to free it to avoid memory leakage. */ | |
tmphstbuf = malloc (hstbuflen); | |
while ((res = gethostbyname_r (host, &hostbuf, tmphstbuf, hstbuflen, | |
&hp, &herr)) == ERANGE) | |
{ | |
/* Enlarge the buffer. */ | |
hstbuflen *= 2; | |
tmphstbuf = realloc (tmphstbuf, hstbuflen); | |
} | |
if (res != 0 || hp == NULL) | |
{ | |
printf ("gethostbyname_r failed: %s (errno: %m)\n", strerror (res)); | |
if (access ("/etc/resolv.conf", R_OK)) | |
{ | |
puts ("DNS probably not set up"); | |
return 0; | |
} | |
return 1; | |
} | |
printf ("Got: %s %s\n", hp->h_name, | |
inet_ntoa (*(struct in_addr *) hp->h_addr)); | |
return 0; | |
} |