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//========================================================================

//

//      getenv.cxx

//

//      Implementation of the ISO C standard getenv() function

//

//========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under

// the terms of the GNU General Public License as published by the Free

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// WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with eCos; if not, write to the Free Software Foundation, Inc.,

// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

//

// As a special exception, if other files instantiate templates or use macros

// or inline functions from this file, or you compile this file and link it

// with other works to produce a work based on this file, this file does not

// by itself cause the resulting work to be covered by the GNU General Public

// License. However the source code for this file must still be made available

// in accordance with section (3) of the GNU General Public License.

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// this file might be covered by the GNU General Public License.

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// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.

// at http://sources.redhat.com/ecos/ecos-license/

// -------------------------------------------

//####ECOSGPLCOPYRIGHTEND####

//========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):    jlarmour

// Contributors: 

// Date:         2000-04-30

// Purpose:     

// Description: 

// Usage:       

//

//####DESCRIPTIONEND####

//

//========================================================================

// CONFIGURATION

#include <pkgconf/libc_stdlib.h>           // Configuration header

// INCLUDES

#include <cyg/infra/cyg_type.h>     // Common type definitions and support

#include <cyg/infra/cyg_ass.h>      // Tracing support

#include <cyg/infra/cyg_trac.h>     // Tracing support

#include <stdlib.h>                 // Main header for stdlib functions

#include <string.h>                 // strchr(), strlen() and strncmp()

// VARIABLES

externC char **environ;   // standard definition of environ

// FUNCTIONS

extern char *

getenv( const char *name )

{

    // This function assumes the POSIX 1003.1 layout of the environment

    // in the environ variable, i.e. extern char **environ is a pointer

    // to an array of character pointers to the environment strings 

    // (POSIX 3.1.2.2 and 2.6).

    //

    // getenv() searches the environment list for a string of the form

    // "name=value" (POSIX 4.6.1). The strings must have this form

    // (POSIX 2.6)

    CYG_REPORT_FUNCNAMETYPE( "getenv", "returning %08x" );

    CYG_PRECONDITION( name != NULL, "getenv() called with NULL string!" );

    CYG_REPORT_FUNCARG1( "name=%s", name );

    CYG_PRECONDITION( environ != NULL,

                      "environ not set i.e. environ == NULL" );

    CYG_CHECK_DATA_PTR( environ, "environ isn't a valid pointer!" );

    CYG_CHECK_DATA_PTR( name, "name isn't a valid pointer!" );

    // check name doesn't contain '='

    CYG_PRECONDITION( strchr(name, '=') == NULL,

                      "name contains '='!" );

    char **env_str_p;

    cyg_ucount32 len = strlen( name );

    for (env_str_p = environ; *env_str_p != NULL; ++env_str_p ) {

        CYG_CHECK_DATA_PTR( env_str_p,

                            "current environment string isn't valid!" );

        CYG_CHECK_DATA_PTR( *env_str_p,

                            "current environment string isn't valid!" );

        // do we have a match?

        if ( !strncmp(*env_str_p, name, len) ) {

            // but it could be just a prefix i.e. we could have

            // matched MYNAMEFRED when we're looking for just MYNAME, so:

            if ( (*env_str_p)[len] == '=' ) {

                // we got a match

                CYG_REPORT_RETVAL( *env_str_p + len + 1 );

                return (*env_str_p + len + 1);

            } // if

        } // if

        // check the next pointer isn't NULL, as we're about to dereference

        // it

        CYG_ASSERT( env_str_p+1 != NULL,

                    "environment contains a NULL pointer!" );

    } // for

    CYG_REPORT_RETVAL( NULL );

    return NULL;

} // getenv()

// EOF getenv.cxx