glibc/sysdeps/generic/getenv.c

/* Copyright (C) 1991, 1992, 1994, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifndef	HAVE_GNU_LD
#define	__environ	environ
#endif

/* Return the value of the environment variable NAME.  */
char *
getenv (name)
     const char *name;
{
  const size_t len = strlen (name);
  char **ep;

  if (__environ == NULL)
    return NULL;

  for (ep = __environ; *ep != NULL; ++ep)
    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
      return &(*ep)[len + 1];

  return NULL;
}


/* Some programs and especially the libc itself have to be careful
   what values to accept from the environment.  This special version
   checks for SUID or SGID first before doing any work.  */
char *
__secure_getenv (name)
     const char *name;
{
  return __libc_enable_secure ? NULL : getenv (name);
}