sysdeps/posix/cuserid.c

   1 /* Copyright (C) 1991, 1996 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 not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <pwd.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <sys/types.h>
  24
  25 /* Return the username of the caller.
  26    If S is not NULL, it points to a buffer of at least L_cuserid bytes
  27    into which the name is copied; otherwise, a static buffer is used.  */
  28 char *
  29 cuserid (s)
  30      char *s;
  31 {
  32   static char name[L_cuserid];
  33   char buf[NSS_BUFLEN_PASSWD];
  34   struct passwd pwent;
  35   struct passwd *pwptr;
  36
  37   if (__getpwuid_r (geteuid (), &pwent, buf, sizeof (buf), &pwptr))
  38     {
  39       if (s != NULL)
  40         s[0] = '\0';
  41       return NULL;
  42     }
  43
  44   if (s == NULL)
  45     s = name;
  46   return strncpy (s, pwptr->pw_name, L_cuserid);
  47 }