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glibc  2.9
getlogin_r.c File Reference
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include <fcntl.h>
#include <utmp.h>
#include "../login/utmp-private.h"

Go to the source code of this file.


int getlogin_r (char *name, size_t name_len)

Function Documentation

int getlogin_r ( char *  name,
size_t  name_len 

Definition at line 35 of file getlogin_r.c.

  char tty_pathname[2 + 2 * NAME_MAX];
  char *real_tty_path = tty_pathname;
  int result;
  struct utmp *ut, line, buffer;

  /* Get name of tty connected to fd 0.  Return 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().  */

  result = __ttyname_r (0, real_tty_path, sizeof (tty_pathname));

  if (result != 0)
    return result;

  real_tty_path += 5;              /* Remove "/dev/".  */
  strncpy (line.ut_line, real_tty_path, sizeof line.ut_line);

  /* We don't use the normal entry points __setutent et al, because we
     want setutent + getutline_r + endutent all to happen with the lock
     held so that our search is thread-safe.  */

  __libc_lock_lock (__libc_utmp_lock);
  (*__libc_utmp_jump_table->setutent) ();
  result = (*__libc_utmp_jump_table->getutline_r) (&line, &buffer, &ut);
  if (result < 0)
      if (errno == ESRCH)
       /* The caller expects ENOENT if nothing is found.  */
       result = ENOENT;
       result = errno;
  (*__libc_utmp_jump_table->endutent) ();
  __libc_utmp_jump_table = &__libc_utmp_unknown_functions;
  __libc_lock_unlock (__libc_utmp_lock);

  if (result == 0)
      size_t needed = strlen (ut->ut_user) + 1;

      if (needed > name_len)
         __set_errno (ERANGE);
         result = ERANGE;
         memcpy (name, ut->ut_user, needed);
         result = 0;

  return result;

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