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glibc  2.9
cuserid.c
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00001 /* Copyright (C) 1991, 1996, 1998, 1999, 2001 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <pwd.h>
00020 #include <stdio.h>
00021 #include <string.h>
00022 #include <unistd.h>
00023 #include <sys/types.h>
00024 
00025 /* Return the username of the caller.
00026    If S is not NULL, it points to a buffer of at least L_cuserid bytes
00027    into which the name is copied; otherwise, a static buffer is used.  */
00028 char *
00029 cuserid (s)
00030      char *s;
00031 {
00032   static char name[L_cuserid];
00033   char buf[NSS_BUFLEN_PASSWD];
00034   struct passwd pwent;
00035   struct passwd *pwptr;
00036 
00037   if (__getpwuid_r (__geteuid (), &pwent, buf, sizeof (buf), &pwptr)
00038       || pwptr == NULL)
00039     {
00040       if (s != NULL)
00041        s[0] = '\0';
00042       return s;
00043     }
00044 
00045   if (s == NULL)
00046     s = name;
00047   return strncpy (s, pwptr->pw_name, L_cuserid);
00048 }