release/src/router/busybox/coreutils/logname.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini logname implementation for busybox
   4  *
   5  * Copyright (C) 2000  Edward Betts <edward@debian.org>.
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 /* BB_AUDIT SUSv3 compliant */
  11 /* http://www.opengroup.org/onlinepubs/007904975/utilities/logname.html */
  12
  13 /* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
  14  *
  15  * SUSv3 specifies the string used is that returned from getlogin().
  16  * The previous implementation used getpwuid() for geteuid(), which
  17  * is _not_ the same.  Erik apparently made this change almost 3 years
  18  * ago to avoid failing when no utmp was available.  However, the
  19  * correct course of action wrt SUSv3 for a failing getlogin() is
  20  * a diagnostic message and an error return.
  21  */
  22
  23 //usage:#define logname_trivial_usage
  24 //usage:       ""
  25 //usage:#define logname_full_usage "\n\n"
  26 //usage:       "Print the name of the current user"
  27 //usage:
  28 //usage:#define logname_example_usage
  29 //usage:       "$ logname\n"
  30 //usage:       "root\n"
  31
  32 #include "libbb.h"
  33
  34 /* This is a NOFORK applet. Be very careful! */
  35
  36 int logname_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  37 int logname_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
  38 {
  39         char buf[64];
  40
  41         if (argv[1]) {
  42                 bb_show_usage();
  43         }
  44
  45         /* Using _r function - avoid pulling in static buffer from libc */
  46         if (getlogin_r(buf, sizeof(buf)) == 0) {
  47                 puts(buf);
  48                 return fflush_all();
  49         }
  50
  51         bb_perror_msg_and_die("getlogin");
  52 }