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#define _FILE_OFFSET_BITS 64
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <resolv.h>
int main() {
/* in glibc 2.28+ and _FILE_OFFSET_BITS=64 fcntl is #define'd to fcntl64
* Thus headers say `fcntl64` exists, but libc.so.6 (the old one)
* disagrees, resulting in a linking error unless headers are made
* backwards-compatible.
*
* Glibc 2.28+:
* FUNC GLOBAL DEFAULT UND fcntl64@GLIBC_2.28 (3):
*
* Glibc 2.27 or older:
* FUNC GLOBAL DEFAULT UND fcntl@GLIBC_2.2.5
*/
printf("address to fcntl: %p\n", fcntl);
/* The following functions became symbols of their own right with glibc
* 2.34+. Before 2.34 resolv.h would #define res_search __res_search; and
* __res_search is a valid symbol since the beginning of time.
*
* On glibc 2.34+ these symbols are linked this way:
* FUNC GLOBAL DEFAULT UND res_search@GLIBC_2.34 (2)
*
* Pre-glibc 2.34:
* FUNC GLOBAL DEFAULT UND __res_search@GLIBC_2.2.5 (4)
*/
printf("address to res_search: %p\n", res_search);
printf("address to res_nsearch: %p\n", res_nsearch);
printf("address to res_query: %p\n", res_query);
printf("address to res_nquery: %p\n", res_nquery);
printf("address to res_querydomain: %p\n", res_querydomain);
printf("address to res_nquerydomain: %p\n", res_nquerydomain);
printf("address to dn_skipname: %p\n", dn_skipname);
printf("address to dn_comp: %p\n", dn_comp);
printf("address to dn_expand: %p\n", dn_expand);
}
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