/* 
   gcc xxx.c -o xxx
*/

#include <stdio.h>
#include <unistd.h>

#include <pwd.h>

int main()
{
  char buf[64];
  int  ret = getlogin_r(buf, sizeof(buf));

  printf("getlogin='%s'; _r='%s', ret=%d\n",
	 getlogin(), buf, ret);

  char cbuf[64];
  cuserid(cbuf); /* return value seems random ?? */
  printf("cuserid='%s'\n", cbuf);

  uid_t id = geteuid();
  struct passwd pwd, *ppwd;
  char bufbuf[1024];
  int pret = getpwuid_r(id, &pwd, bufbuf, sizeof(bufbuf), &ppwd);

  printf("getpwuid='%s' -- %p vs %p\n", ppwd->pw_name, &pwd, ppwd);

  return 0;
}