sysdeps/posix/cuserid.c

   1 /* Copyright (C) 1991 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <pwd.h>
  23
  24 extern int EXFUN(geteuid, (NOARGS));
  25
  26
  27 /* Return the username of the caller.
  28    If S is not NULL, it points to a buffer of at least L_cuserid bytes
  29    into which the name is copied; otherwise, a static buffer is used.  */
  30 char *
  31 DEFUN(cuserid, (s), char *s)
  32 {
  33   static char name[L_cuserid];
  34   struct passwd *pwent = getpwuid(geteuid());
  35
  36   if (pwent == NULL)
  37     {
  38       if (s != NULL)
  39         s[0] = '\0';
  40       return NULL;
  41     }
  42
  43   if (s == NULL)
  44     s = name;
  45   return strcpy(s, pwent->pw_name);
  46 }