Runkit_Sandbox_Parent

Description

Instantiating the Runkit_Sandbox_Parent class from within a sandbox environment created from the Runkit_Sandbox class provides some (controlled) means for a sandbox child to access its parent.

In order for any of the Runkit_Sandbox_Parent features to function. Support must be enabled on a per-sandbox basis by enabling the parent_access flag from the parent's context.

<?php
$sandbox = new Runkit_Sandbox();
$sandbox['parent_access'] = true;
?>

Accessing the Parent's Variables

Just as with sandbox variable access, a sandbox parent's variables may be read from and written to as properties of the Runkit_Sandbox_Parent class. Read access to parental variables may be enabled with the parent_read setting (in addition to the base parent_access setting). Write access, in turn, is enabled through the parent_write setting.

Unlike sandbox child variable access, the variable scope is not limited to globals only. By setting the parent_scope setting to an appropriate integer value, other scopes in the active call stack may be inspected instead. A value of 0 (Default) will direct variable access at the global scope. 1 will point variable access at whatever variable scope was active at the time the current block of sandbox code was executed. Higher values progress back through the functions that called the functions that led to the sandbox executing code that tried to access its own parent's variables.

<?php
$php = new Runkit_Sandbox();
$php['parent_access'] = true;
$php['parent_read'] = true;

$test = "Global";

$php->eval('$PARENT = new Runkit_Sandbox_Parent;');

$php['parent_scope'] = 0;
one();

$php['parent_scope'] = 1;
one();

$php['parent_scope'] = 2;
one();

$php['parent_scope'] = 3;
one();

$php['parent_scope'] = 4;
one();

$php['parent_scope'] = 5;
one();

function one() {
    $test = "one()";
    two();
}

function two() {
    $test = "two()";
    three();
}

function three() {
    $test = "three()";
    $GLOBALS['php']->eval('var_dump($PARENT->test);');
}
?>

The above example will output:

string(6) "Global"
string(7) "three()"
string(5) "two()"
string(5) "one()"
string(6) "Global"
string(6) "Global"

Calling the Parent's Functions

Just as with sandbox access, a sandbox may access its parents functions providing that the proper settings have been enabled. Enabling parent_call will allow the sandbox to call all functions available to the parent scope. Language constructs are each controlled by their own setting: print() and echo() are enabled with parent_echo. die() and exit() are enabled with parent_die. eval() is enabled with parent_eval while include(), include_once(), require(), and require_once() are enabled through parent_include.