Back to index

glibc  2.9
getlogin.c File Reference
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include <fcntl.h>
#include <utmp.h>

Go to the source code of this file.


char * getlogin (void)

Function Documentation

char* getlogin ( void  )

Definition at line 32 of file getlogin.c.

  char tty_pathname[2 + 2 * NAME_MAX];
  char *real_tty_path = tty_pathname;
  char *result = NULL;
  static char name[UT_NAMESIZE + 1];
  struct utmp *ut, line, buffer;

  /* Get name of tty connected to fd 0.  Return NULL if not a tty or
     if fd 0 isn't open.  Note that a lot of documentation says that
     getlogin() is based on the controlling terminal---what they
     really mean is "the terminal connected to standard input".  The
     getlogin() implementation of DEC Unix, SunOS, Solaris, HP-UX all
     return NULL if fd 0 has been closed, so this is the compatible
     thing to do.  Note that ttyname(open("/dev/tty")) on those
     systems returns /dev/tty, so that is not a possible solution for
     getlogin().  */
  if (__ttyname_r (0, real_tty_path, sizeof (tty_pathname)) != 0)
    return NULL;

  real_tty_path += 5;              /* Remove "/dev/".  */

  __setutent ();
  strncpy (line.ut_line, real_tty_path, sizeof line.ut_line);
  if (__getutline_r (&line, &buffer, &ut) < 0)
      if (errno == ESRCH)
       /* The caller expects ENOENT if nothing is found.  */
       __set_errno (ENOENT);
      result = NULL;
      strncpy (name, ut->ut_user, UT_NAMESIZE);
      name[UT_NAMESIZE] = '\0';
      result = name;

  __endutent ();

  return result;

Here is the call graph for this function: