1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  *      Copyright (c) 2013 Gary Mills
  24  *
  25  *      Copyright (c) 1996 by Sun Microsystems, Inc.
  26  *
  27  * Truncate a long login name returned by getlogin()
  28  * for programs that copy the name to a nine-byte buffer.
  29  *
  30  * Use:
  31  *      LD_PRELOAD=getlogin8.so.1 program args ...
  32  *
  33  */
  34 
  35 #include <unistd.h>
  36 #include <dlfcn.h>
  37 #include <string.h>
  38 
  39 /* Traditional length limit */
  40 #define TRAD_LEN_MAX    8
  41 
  42 char *
  43 getlogin(void)
  44 {
  45         static char *(*getlogin_addr)(void) = NULL;
  46         static char buffer[TRAD_LEN_MAX + 1];
  47         char *p;
  48 
  49         if (getlogin_addr == NULL)
  50                 getlogin_addr = (char *(*)(void))dlsym(RTLD_NEXT,
  51                     "getlogin");
  52         if ((p = (*getlogin_addr)()) == NULL)
  53                 return (NULL);
  54         (void)strlcpy(buffer, p, sizeof (buffer));
  55         return (buffer);
  56 }
  57 
  58 /* */