lib/roken/get_default_username.c

   1 /*
   2  * Copyright (c) 1997 - 1999 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include <config.h>
  35
  36 #include "roken.h"
  37
  38 /*
  39  * Try to return what should be considered the default username or
  40  * NULL if we can't guess at all.
  41  */
  42
  43 const char * ROKEN_LIB_FUNCTION
  44 get_default_username (void)
  45 {
  46     const char *user;
  47
  48     user = getenv ("USER");
  49     if (user == NULL)
  50         user = getenv ("LOGNAME");
  51     if (user == NULL)
  52         user = getenv ("USERNAME");
  53
  54 #if defined(HAVE_GETLOGIN) && !defined(POSIX_GETLOGIN)
  55     if (user == NULL) {
  56         user = (const char *)getlogin ();
  57         if (user != NULL)
  58             return user;
  59     }
  60 #endif
  61 #ifdef HAVE_PWD_H
  62     {
  63         uid_t uid = getuid ();
  64         struct passwd *pwd;
  65
  66         if (user != NULL) {
  67             pwd = k_getpwnam (user);
  68             if (pwd != NULL && pwd->pw_uid == uid)
  69                 return user;
  70         }
  71         pwd = k_getpwuid (uid);
  72         if (pwd != NULL)
  73             return pwd->pw_name;
  74     }
  75 #endif
  76     return user;
  77 }