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<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"/><meta name="viewport" content="width=device-width, initial-scale=0.8"/><title>6.8 Protected Exports</title><link rel="stylesheet" type="text/css" href="../scribble.css" title="default"/><link rel="stylesheet" type="text/css" href="../racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-style.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../manual-racket.css" title="default"/><link rel="stylesheet" type="text/css" href="../doc-site.css" title="default"/><script type="text/javascript" src="../scribble-common.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../manual-racket.js"></script><script type="text/javascript" src="../doc-site.js"></script><script type="text/javascript" src="../local-redirect/local-redirect.js"></script><script type="text/javascript" src="../local-redirect/local-user-redirect.js"></script><!--[if IE 6]><style type="text/css">.SIEHidden { overflow: hidden; }</style><![endif]--></head><body id="doc-racket-lang-org"><div class="tocset"><div class="tocview"><div class="tocviewlist tocviewlisttopspace"><div class="tocviewtitle"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_0");">►</a></td><td></td><td><a href="index.html" class="tocviewlink" data-pltdoc="x">The Racket Guide</a></td></tr></table></div><div class="tocviewsublisttop" style="display: none;" id="tocview_0"><table cellspacing="0" cellpadding="0"><tr><td align="right">1 </td><td><a href="intro.html" class="tocviewlink" data-pltdoc="x">Welcome to Racket</a></td></tr><tr><td align="right">2 </td><td><a href="to-scheme.html" class="tocviewlink" data-pltdoc="x">Racket Essentials</a></td></tr><tr><td align="right">3 </td><td><a href="datatypes.html" class="tocviewlink" data-pltdoc="x">Built-<wbr></wbr>In Datatypes</a></td></tr><tr><td align="right">4 </td><td><a href="scheme-forms.html" class="tocviewlink" data-pltdoc="x">Expressions and Definitions</a></td></tr><tr><td align="right">5 </td><td><a href="define-struct.html" class="tocviewlink" data-pltdoc="x">Programmer-<wbr></wbr>Defined Datatypes</a></td></tr><tr><td align="right">6 </td><td><a href="modules.html" class="tocviewselflink" data-pltdoc="x">Modules</a></td></tr><tr><td align="right">7 </td><td><a href="contracts.html" class="tocviewlink" data-pltdoc="x">Contracts</a></td></tr><tr><td align="right">8 </td><td><a href="i_o.html" class="tocviewlink" data-pltdoc="x">Input and Output</a></td></tr><tr><td align="right">9 </td><td><a href="regexp.html" class="tocviewlink" data-pltdoc="x">Regular Expressions</a></td></tr><tr><td align="right">10 </td><td><a href="control.html" class="tocviewlink" data-pltdoc="x">Exceptions and Control</a></td></tr><tr><td align="right">11 </td><td><a href="for.html" class="tocviewlink" data-pltdoc="x">Iterations and Comprehensions</a></td></tr><tr><td align="right">12 </td><td><a href="match.html" class="tocviewlink" data-pltdoc="x">Pattern Matching</a></td></tr><tr><td align="right">13 </td><td><a href="classes.html" class="tocviewlink" data-pltdoc="x">Classes and Objects</a></td></tr><tr><td align="right">14 </td><td><a href="units.html" class="tocviewlink" data-pltdoc="x">Units</a></td></tr><tr><td align="right">15 </td><td><a href="reflection.html" class="tocviewlink" data-pltdoc="x">Reflection and Dynamic Evaluation</a></td></tr><tr><td align="right">16 </td><td><a href="macros.html" class="tocviewlink" data-pltdoc="x">Macros</a></td></tr><tr><td align="right">17 </td><td><a href="languages.html" class="tocviewlink" data-pltdoc="x">Creating Languages</a></td></tr><tr><td align="right">18 </td><td><a href="concurrency.html" class="tocviewlink" data-pltdoc="x">Concurrency and Synchronization</a></td></tr><tr><td align="right">19 </td><td><a href="performance.html" class="tocviewlink" data-pltdoc="x">Performance</a></td></tr><tr><td align="right">20 </td><td><a href="parallelism.html" class="tocviewlink" data-pltdoc="x">Parallelism</a></td></tr><tr><td align="right">21 </td><td><a href="running.html" class="tocviewlink" data-pltdoc="x">Running and Creating Executables</a></td></tr><tr><td align="right">22 </td><td><a href="More_Libraries.html" class="tocviewlink" data-pltdoc="x">More Libraries</a></td></tr><tr><td align="right">23 </td><td><a href="dialects.html" class="tocviewlink" data-pltdoc="x">Dialects of Racket and Scheme</a></td></tr><tr><td align="right">24 </td><td><a href="other-editors.html" class="tocviewlink" data-pltdoc="x">Command-<wbr></wbr>Line Tools and Your Editor of Choice</a></td></tr><tr><td align="right"></td><td><a href="doc-bibliography.html" class="tocviewlink" data-pltdoc="x">Bibliography</a></td></tr><tr><td align="right"></td><td><a href="doc-index.html" class="tocviewlink" data-pltdoc="x">Index</a></td></tr></table></div></div><div class="tocviewlist"><table cellspacing="0" cellpadding="0"><tr><td style="width: 1em;"><a href="javascript:void(0);" title="Expand/Collapse" class="tocviewtoggle" onclick="TocviewToggle(this,"tocview_1");">▼</a></td><td>6 </td><td><a href="modules.html" class="tocviewlink" data-pltdoc="x">Modules</a></td></tr></table><div class="tocviewsublistbottom" style="display: block;" id="tocview_1"><table cellspacing="0" cellpadding="0"><tr><td align="right">6.1 </td><td><a href="module-basics.html" class="tocviewlink" data-pltdoc="x">Module Basics</a></td></tr><tr><td align="right">6.2 </td><td><a href="Module_Syntax.html" class="tocviewlink" data-pltdoc="x">Module Syntax</a></td></tr><tr><td align="right">6.3 </td><td><a href="module-paths.html" class="tocviewlink" data-pltdoc="x">Module Paths</a></td></tr><tr><td align="right">6.4 </td><td><a href="module-require.html" class="tocviewlink" data-pltdoc="x">Imports:<span class="mywbr"> </span> <span class="RktSym"><span class="RktStxLink">require</span></span></a></td></tr><tr><td align="right">6.5 </td><td><a href="module-provide.html" class="tocviewlink" data-pltdoc="x">Exports:<span class="mywbr"> </span> <span class="RktSym"><span class="RktStxLink">provide</span></span></a></td></tr><tr><td align="right">6.6 </td><td><a href="module-set.html" class="tocviewlink" data-pltdoc="x">Assignment and Redefinition</a></td></tr><tr><td align="right">6.7 </td><td><a href="module-macro.html" class="tocviewlink" data-pltdoc="x">Modules and Macros</a></td></tr><tr><td align="right">6.8 </td><td><a href="protect-out.html" class="tocviewselflink" data-pltdoc="x">Protected Exports</a></td></tr></table></div></div></div></div><div class="maincolumn"><div class="main"><div class="navsettop"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="module-macro.html" title="backward to "6.7 Modules and Macros"" data-pltdoc="x">← prev</a> <a href="modules.html" title="up to "6 Modules"" data-pltdoc="x">up</a> <a href="contracts.html" title="forward to "7 Contracts"" data-pltdoc="x">next →</a></span> </div><h4 x-source-module="(lib "scribblings/guide/guide.scrbl")" x-source-pkg="racket-doc" x-part-tag=""protect-out"">6.8<tt> </tt><a name="(part._protect-out)"></a>Protected Exports</h4><p>Sometimes, a module needs to export bindings to other modules that are
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at the same trust level as the exporting module, while at the same
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time preventing access from untrusted modules. Such exports should use
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the <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._protect-out%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">protect-out</a></span> form in <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._provide%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">provide</a></span>. For example,
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<a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=foreign&rel=index.html&version=8.6" class="RktModLink Sq" data-pltdoc="x"><span class="RktSym">ffi/unsafe</span></a> exports all of its unsafe bindings as
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<a name="(tech._protected)"></a><span style="font-style: italic">protected</span> in this sense.</p><p>Levels of trust are implemented with <a href="code-inspectors_protect.html#%28tech._code._inspector%29" class="techoutside" data-pltdoc="x"><span class="techinside">code inspectors</span></a> (see
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<a href="code-inspectors_protect.html" data-pltdoc="x">Code Inspectors for Trusted and Untrusted Code</a>).
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Only modules loaded with an equally strong code inspector as an
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exporting module can use protected bindings from the exporting module.
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Operations like <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=Module_Names_and_Loading.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._dynamic-require%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">dynamic-require</a></span> are granted access depending
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on the current code inspector as determined by
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<span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=modprotect.html%23%2528def._%2528%2528quote._%7E23%7E25kernel%2529._current-code-inspector%2529%2529&version=8.6" class="RktValLink Sq" data-pltdoc="x">current-code-inspector</a></span>.</p><p>When a module re-exports a protected binding, it does not need to use
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<span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._protect-out%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">protect-out</a></span> again. Access is always determined by the code
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inspector of the module that originally defines a protected binding.
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When using a protected binding within a module, take care to either
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provide new bindings from the module with <span class="RktSym"><a href="https://download.racket-lang.org/releases/8.6/doc/local-redirect/index.html?doc=reference&rel=require.html%23%2528form._%2528%2528lib._racket%252Fprivate%252Fbase..rkt%2529._protect-out%2529%2529&version=8.6" class="RktStxLink Sq" data-pltdoc="x">protect-out</a></span> or
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ensure that no provided bindings expose functionality that was meant
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to be protected in the first place.</p><div class="navsetbottom"><span class="navleft"><form class="searchform"><input class="searchbox" id="searchbox" type="text" tabindex="1" placeholder="...search manuals..." title="Enter a search string to search the manuals" onkeypress="return DoSearchKey(event, this, "8.6", "../");"/></form> <a href="https://docs.racket-lang.org/index.html" title="up to the documentation top" data-pltdoc="x" onclick="return GotoPLTRoot("8.6");">top</a><span class="tocsettoggle"> <a href="javascript:void(0);" title="show/hide table of contents" onclick="TocsetToggle();">contents</a></span></span><span class="navright"> <a href="module-macro.html" title="backward to "6.7 Modules and Macros"" data-pltdoc="x">← prev</a> <a href="modules.html" title="up to "6 Modules"" data-pltdoc="x">up</a> <a href="contracts.html" title="forward to "7 Contracts"" data-pltdoc="x">next →</a></span> </div></div></div><div id="contextindicator"> </div></body></html> |