mirror of
https://github.com/hohn/codeql-info.git
synced 2025-12-16 20:53:04 +01:00
330 lines
26 KiB
HTML
330 lines
26 KiB
HTML
<!DOCTYPE html>
|
||
|
||
<html lang="en" data-content_root="../">
|
||
<head>
|
||
<meta charset="utf-8" />
|
||
<meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="viewport" content="width=device-width, initial-scale=1" />
|
||
|
||
<title>Overflow-prone comparisons in Java — CodeQL</title>
|
||
<link rel="stylesheet" type="text/css" href="../_static/pygments.css?v=fa44fd50" />
|
||
<link rel="stylesheet" type="text/css" href="../_static/alabaster.css?v=93459777" />
|
||
<script src="../_static/documentation_options.js?v=5929fcd5"></script>
|
||
<script src="../_static/doctools.js?v=888ff710"></script>
|
||
<script src="../_static/sphinx_highlight.js?v=dc90522c"></script>
|
||
<link rel="icon" href="../_static/favicon.ico"/>
|
||
<link rel="index" title="Index" href="../genindex.html" />
|
||
<link rel="search" title="Search" href="../search.html" />
|
||
<link rel="next" title="Navigating the call graph" href="navigating-the-call-graph.html" />
|
||
<link rel="prev" title="Types in Java" href="types-in-java.html" />
|
||
|
||
<title>CodeQL docs</title>
|
||
<meta name="viewport" content="width=device-width, initial-scale=1" />
|
||
<link rel="stylesheet" href="../_static/custom.css" type="text/css" />
|
||
<link rel="stylesheet" href="../_static/primer.css" type="text/css" />
|
||
|
||
|
||
</head><body>
|
||
<header class="Header">
|
||
<div class="Header-item--full">
|
||
<a href="https://codeql.github.com/docs" class="Header-link f2 d-flex flex-items-center">
|
||
<!-- <%= octicon "mark-github", class: "mr-2", height: 32 %> -->
|
||
<svg height="32" class="octicon octicon-mark-github mr-2" viewBox="0 0 16 16" version="1.1" width="32"
|
||
aria-hidden="true">
|
||
<path fill-rule="evenodd"
|
||
d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0 0 16 8c0-4.42-3.58-8-8-8z">
|
||
</path>
|
||
</svg>
|
||
<span class="hide-sm">CodeQL documentation</span>
|
||
</a>
|
||
</div>
|
||
<div class="Header-item hide-sm hide-md">
|
||
<script src="https://addsearch.com/js/?key=93b4d287e2fc079a4089412b669785d5&categories=!0xhelp.semmle.com,0xcodeql.github.com,1xdocs,1xcodeql-standard-libraries,1xcodeql-query-help"></script>
|
||
</div>
|
||
<div class="Header-item">
|
||
|
||
<details class="dropdown details-reset details-overlay d-inline-block">
|
||
<summary class="btn bg-gray-dark text-white border" aria-haspopup="true">
|
||
CodeQL resources
|
||
<div class="dropdown-caret"></div>
|
||
</summary>
|
||
|
||
<ul class="dropdown-menu dropdown-menu-se dropdown-menu-dark">
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/docs/codeql-overview">CodeQL overview</a></li>
|
||
<li class="dropdown-divider" role="separator"></li>
|
||
<div class="dropdown-header">
|
||
CodeQL tools
|
||
</div>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/docs/codeql-for-visual-studio-code">CodeQL for VS Code</a>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/docs/codeql-cli">CodeQL CLI</a>
|
||
</li>
|
||
<li class="dropdown-divider" role="separator"></li>
|
||
<div class="dropdown-header">
|
||
CodeQL guides
|
||
</div>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/docs/writing-codeql-queries">Writing CodeQL queries</a></li>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/docs/codeql-language-guides">CodeQL language guides</a>
|
||
<li class="dropdown-divider" role="separator"></li>
|
||
<div class="dropdown-header">
|
||
Reference docs
|
||
</div>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/docs/ql-language-reference/">QL language
|
||
reference</a>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/codeql-standard-libraries">CodeQL
|
||
standard-libraries</a>
|
||
<li><a class="dropdown-item" href="https://codeql.github.com/codeql-query-help">CodeQL
|
||
query help</a>
|
||
<li class="dropdown-divider" role="separator"></li>
|
||
<div class="dropdown-header">
|
||
Source files
|
||
</div>
|
||
<li><a class="dropdown-item" href="https://github.com/github/codeql">CodeQL repository</a>
|
||
</ul>
|
||
</details>
|
||
|
||
</div>
|
||
|
||
</header>
|
||
<main class="bg-gray-light clearfix">
|
||
<nav class="SideNav position-sticky top-0 col-lg-3 col-md-3 float-left p-4 hide-sm hide-md overflow-y-auto">
|
||
|
||
<ul class="current">
|
||
<li class="toctree-l1"><a class="reference internal" href="../codeql-overview/index.html">CodeQL overview</a></li>
|
||
<li class="toctree-l1"><a class="reference internal" href="../codeql-for-visual-studio-code/index.html">CodeQL for Visual Studio Code</a></li>
|
||
<li class="toctree-l1"><a class="reference internal" href="../codeql-cli/index.html">CodeQL CLI</a></li>
|
||
<li class="toctree-l1"><a class="reference internal" href="../writing-codeql-queries/index.html">Writing CodeQL queries</a></li>
|
||
<li class="toctree-l1 current"><a class="reference internal" href="index.html">CodeQL language guides</a><ul class="current">
|
||
<li class="toctree-l2"><a class="reference internal" href="codeql-for-cpp.html">CodeQL for C and C++</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="codeql-for-csharp.html">CodeQL for C#</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="codeql-for-go.html">CodeQL for Go</a></li>
|
||
<li class="toctree-l2 current"><a class="reference internal" href="codeql-for-java.html">CodeQL for Java</a><ul class="current">
|
||
<li class="toctree-l3"><a class="reference internal" href="basic-query-for-java-code.html">Basic query for Java code</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="codeql-library-for-java.html">CodeQL library for Java</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="analyzing-data-flow-in-java.html">Analyzing data flow in Java</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="types-in-java.html">Types in Java</a></li>
|
||
<li class="toctree-l3 current"><a class="current reference internal" href="#">Overflow-prone comparisons in Java</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="navigating-the-call-graph.html">Navigating the call graph</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="annotations-in-java.html">Annotations in Java</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="javadoc.html">Javadoc</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="working-with-source-locations.html">Working with source locations</a></li>
|
||
<li class="toctree-l3"><a class="reference internal" href="abstract-syntax-tree-classes-for-working-with-java-programs.html">Abstract syntax tree classes for working with Java programs</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l2"><a class="reference internal" href="codeql-for-javascript.html">CodeQL for JavaScript</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="codeql-for-python.html">CodeQL for Python</a></li>
|
||
<li class="toctree-l2"><a class="reference internal" href="codeql-for-ruby.html">CodeQL for Ruby</a></li>
|
||
</ul>
|
||
</li>
|
||
<li class="toctree-l1"><a class="reference internal" href="../ql-language-reference/index.html">QL language reference</a></li>
|
||
</ul>
|
||
|
||
|
||
</nav>
|
||
|
||
|
||
<div class="body col-sm-12 col-md-9 col-lg-9 float-left border-left">
|
||
|
||
<div class="hide-lg hide-xl px-4 pt-4">
|
||
|
||
<div class="related" role="navigation" aria-label="related navigation">
|
||
<ul>
|
||
<li class="nav-item nav-item-0"><a href="../contents.html">CodeQL</a> »</li>
|
||
<li class="nav-item nav-item-1"><a href="index.html"
|
||
>CodeQL language guides</a> »</li>
|
||
<li class="nav-item nav-item-2"><a href="codeql-for-java.html"
|
||
accesskey="U">CodeQL for Java</a> »</li>
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
|
||
<article class="p-4 col-lg-10 col-md-10 col-sm-12">
|
||
|
||
<section id="overflow-prone-comparisons-in-java">
|
||
<span id="id1"></span><h1>Overflow-prone comparisons in Java<a class="headerlink" href="#overflow-prone-comparisons-in-java" title="Link to this heading">¶</a></h1>
|
||
<p>You can use CodeQL to check for comparisons in Java code where one side of the comparison is prone to overflow.</p>
|
||
<section id="about-this-article">
|
||
<h2>About this article<a class="headerlink" href="#about-this-article" title="Link to this heading">¶</a></h2>
|
||
<p>In this tutorial article you’ll write a query for finding comparisons between integers and long integers in loops that may lead to non-termination due to overflow.</p>
|
||
<p>To begin, consider this code snippet:</p>
|
||
<div class="highlight-java notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span><span class="w"> </span><span class="nf">foo</span><span class="p">(</span><span class="kt">long</span><span class="w"> </span><span class="n">l</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||
<span class="w"> </span><span class="k">for</span><span class="p">(</span><span class="kt">int</span><span class="w"> </span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o"><</span><span class="n">l</span><span class="p">;</span><span class="w"> </span><span class="n">i</span><span class="o">++</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
|
||
<span class="w"> </span><span class="c1">// do something</span>
|
||
<span class="w"> </span><span class="p">}</span>
|
||
<span class="p">}</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>If <code class="docutils literal notranslate"><span class="pre">l</span></code> is bigger than 2<sup>31</sup>- 1 (the largest positive value of type <code class="docutils literal notranslate"><span class="pre">int</span></code>), then this loop will never terminate: <code class="docutils literal notranslate"><span class="pre">i</span></code> will start at zero, being incremented all the way up to 2<sup>31</sup>- 1, which is still smaller than <code class="docutils literal notranslate"><span class="pre">l</span></code>. When it is incremented once more, an arithmetic overflow occurs, and <code class="docutils literal notranslate"><span class="pre">i</span></code> becomes -2<sup>31</sup>, which also is smaller than <code class="docutils literal notranslate"><span class="pre">l</span></code>! Eventually, <code class="docutils literal notranslate"><span class="pre">i</span></code> will reach zero again, and the cycle repeats.</p>
|
||
<blockquote class="pull-quote">
|
||
<div><p>More about overflow</p>
|
||
<p>All primitive numeric types have a maximum value, beyond which they will wrap around to their lowest possible value (called an “overflow”). For <code class="docutils literal notranslate"><span class="pre">int</span></code>, this maximum value is 2<sup>31</sup>- 1. Type <code class="docutils literal notranslate"><span class="pre">long</span></code> can accommodate larger values up to a maximum of 2<sup>63</sup>- 1. In this example, this means that <code class="docutils literal notranslate"><span class="pre">l</span></code> can take on a value that is higher than the maximum for type <code class="docutils literal notranslate"><span class="pre">int</span></code>; <code class="docutils literal notranslate"><span class="pre">i</span></code> will never be able to reach this value, instead overflowing and returning to a low value.</p>
|
||
</div></blockquote>
|
||
<p>We’re going to develop a query that finds code that looks like it might exhibit this kind of behavior. We’ll be using several of the standard library classes for representing statements and functions. For a full list, see “<a class="reference internal" href="abstract-syntax-tree-classes-for-working-with-java-programs.html"><span class="doc">Abstract syntax tree classes for working with Java programs</span></a>.”</p>
|
||
</section>
|
||
<section id="initial-query">
|
||
<h2>Initial query<a class="headerlink" href="#initial-query" title="Link to this heading">¶</a></h2>
|
||
<p>We’ll start by writing a query that finds less-than expressions (CodeQL class <code class="docutils literal notranslate"><span class="pre">LTExpr</span></code>) where the left operand is of type <code class="docutils literal notranslate"><span class="pre">int</span></code> and the right operand is of type <code class="docutils literal notranslate"><span class="pre">long</span></code>:</p>
|
||
<div class="highlight-ql notranslate"><div class="highlight"><pre><span></span>import java
|
||
|
||
from LTExpr expr
|
||
where expr.getLeftOperand().getType().hasName("int") and
|
||
expr.getRightOperand().getType().hasName("long")
|
||
select expr
|
||
</pre></div>
|
||
</div>
|
||
<p>➤ <a class="reference external" href="https://lgtm.com/query/490866529746563234/">See this in the query console on LGTM.com</a>. This query usually finds results on most projects.</p>
|
||
<p>Notice that we use the predicate <code class="docutils literal notranslate"><span class="pre">getType</span></code> (available on all subclasses of <code class="docutils literal notranslate"><span class="pre">Expr</span></code>) to determine the type of the operands. Types, in turn, define the <code class="docutils literal notranslate"><span class="pre">hasName</span></code> predicate, which allows us to identify the primitive types <code class="docutils literal notranslate"><span class="pre">int</span></code> and <code class="docutils literal notranslate"><span class="pre">long</span></code>. As it stands, this query finds <em>all</em> less-than expressions comparing <code class="docutils literal notranslate"><span class="pre">int</span></code> and <code class="docutils literal notranslate"><span class="pre">long</span></code>, but in fact we are only interested in comparisons that are part of a loop condition. Also, we want to filter out comparisons where either operand is constant, since these are less likely to be real bugs. The revised query looks like this:</p>
|
||
<div class="highlight-ql notranslate"><div class="highlight"><pre><span></span>import java
|
||
|
||
from LTExpr expr
|
||
where expr.getLeftOperand().getType().hasName("int") and
|
||
expr.getRightOperand().getType().hasName("long") and
|
||
exists(LoopStmt l | l.getCondition().getAChildExpr*() = expr) and
|
||
not expr.getAnOperand().isCompileTimeConstant()
|
||
select expr
|
||
</pre></div>
|
||
</div>
|
||
<p>➤ <a class="reference external" href="https://lgtm.com/query/4315986481180063825/">See this in the query console on LGTM.com</a>. Notice that fewer results are found.</p>
|
||
<p>The class <code class="docutils literal notranslate"><span class="pre">LoopStmt</span></code> is a common superclass of all loops, including, in particular, <code class="docutils literal notranslate"><span class="pre">for</span></code> loops as in our example above. While different kinds of loops have different syntax, they all have a loop condition, which can be accessed through predicate <code class="docutils literal notranslate"><span class="pre">getCondition</span></code>. We use the reflexive transitive closure operator <code class="docutils literal notranslate"><span class="pre">*</span></code> applied to the <code class="docutils literal notranslate"><span class="pre">getAChildExpr</span></code> predicate to express the requirement that <code class="docutils literal notranslate"><span class="pre">expr</span></code> should be nested inside the loop condition. In particular, it can be the loop condition itself.</p>
|
||
<p>The final conjunct in the <code class="docutils literal notranslate"><span class="pre">where</span></code> clause takes advantage of the fact that <a class="reference internal" href="../ql-language-reference/predicates.html#predicates"><span class="std std-ref">predicates</span></a> can return more than one value (they are really relations). In particular, <code class="docutils literal notranslate"><span class="pre">getAnOperand</span></code> may return <em>either</em> operand of <code class="docutils literal notranslate"><span class="pre">expr</span></code>, so <code class="docutils literal notranslate"><span class="pre">expr.getAnOperand().isCompileTimeConstant()</span></code> holds if at least one of the operands is constant. Negating this condition means that the query will only find expressions where <em>neither</em> of the operands is constant.</p>
|
||
</section>
|
||
<section id="generalizing-the-query">
|
||
<h2>Generalizing the query<a class="headerlink" href="#generalizing-the-query" title="Link to this heading">¶</a></h2>
|
||
<p>Of course, comparisons between <code class="docutils literal notranslate"><span class="pre">int</span></code> and <code class="docutils literal notranslate"><span class="pre">long</span></code> are not the only problematic case: any less-than comparison between a narrower and a wider type is potentially suspect, and less-than-or-equals, greater-than, and greater-than-or-equals comparisons are just as problematic as less-than comparisons.</p>
|
||
<p>In order to compare the ranges of types, we define a predicate that returns the width (in bits) of a given integral type:</p>
|
||
<div class="highlight-ql notranslate"><div class="highlight"><pre><span></span>int width(PrimitiveType pt) {
|
||
(pt.hasName("byte") and result=8) or
|
||
(pt.hasName("short") and result=16) or
|
||
(pt.hasName("char") and result=16) or
|
||
(pt.hasName("int") and result=32) or
|
||
(pt.hasName("long") and result=64)
|
||
}
|
||
</pre></div>
|
||
</div>
|
||
<p>We now want to generalize our query to apply to any comparison where the width of the type on the smaller end of the comparison is less than the width of the type on the greater end. Let’s call such a comparison <em>overflow prone</em>, and introduce an abstract class to model it:</p>
|
||
<div class="highlight-ql notranslate"><div class="highlight"><pre><span></span>abstract class OverflowProneComparison extends ComparisonExpr {
|
||
Expr getLesserOperand() { none() }
|
||
Expr getGreaterOperand() { none() }
|
||
}
|
||
</pre></div>
|
||
</div>
|
||
<p>There are two concrete child classes of this class: one for <code class="docutils literal notranslate"><span class="pre"><=</span></code> or <code class="docutils literal notranslate"><span class="pre"><</span></code> comparisons, and one for <code class="docutils literal notranslate"><span class="pre">>=</span></code> or <code class="docutils literal notranslate"><span class="pre">></span></code> comparisons. In both cases, we implement the constructor in such a way that it only matches the expressions we want:</p>
|
||
<div class="highlight-ql notranslate"><div class="highlight"><pre><span></span>class LTOverflowProneComparison extends OverflowProneComparison {
|
||
LTOverflowProneComparison() {
|
||
(this instanceof LEExpr or this instanceof LTExpr) and
|
||
width(this.getLeftOperand().getType()) < width(this.getRightOperand().getType())
|
||
}
|
||
}
|
||
|
||
class GTOverflowProneComparison extends OverflowProneComparison {
|
||
GTOverflowProneComparison() {
|
||
(this instanceof GEExpr or this instanceof GTExpr) and
|
||
width(this.getRightOperand().getType()) < width(this.getLeftOperand().getType())
|
||
}
|
||
}
|
||
</pre></div>
|
||
</div>
|
||
<p>Now we rewrite our query to make use of these new classes:</p>
|
||
<div class="highlight-ql notranslate"><div class="highlight"><pre><span></span>import Java
|
||
|
||
// Insert the class definitions from above
|
||
|
||
from OverflowProneComparison expr
|
||
where exists(LoopStmt l | l.getCondition().getAChildExpr*() = expr) and
|
||
not expr.getAnOperand().isCompileTimeConstant()
|
||
select expr
|
||
</pre></div>
|
||
</div>
|
||
<p>➤ <a class="reference external" href="https://lgtm.com/query/506868054626167462/">See the full query in the query console on LGTM.com</a>.</p>
|
||
</section>
|
||
<section id="further-reading">
|
||
<h2>Further reading<a class="headerlink" href="#further-reading" title="Link to this heading">¶</a></h2>
|
||
<ul class="simple">
|
||
<li><p><a class="reference external" href="https://github.com/github/codeql/tree/main/java/ql/src">CodeQL queries for Java</a></p></li>
|
||
<li><p><a class="reference external" href="https://github.com/github/codeql/tree/main/java/ql/examples">Example queries for Java</a></p></li>
|
||
<li><p><a class="reference external" href="https://codeql.github.com/codeql-standard-libraries/java/">CodeQL library reference for Java</a></p></li>
|
||
</ul>
|
||
<ul class="simple">
|
||
<li><p>“<a class="reference internal" href="../ql-language-reference/index.html#ql-language-reference"><span class="std std-ref">QL language reference</span></a>”</p></li>
|
||
<li><p>“<a class="reference internal" href="../codeql-overview/codeql-tools.html#codeql-tools"><span class="std std-ref">CodeQL tools</span></a>”</p></li>
|
||
</ul>
|
||
</section>
|
||
</section>
|
||
|
||
|
||
</article>
|
||
|
||
<!-- GitHub footer, with links to terms and privacy statement -->
|
||
<div class="px-3 px-md-6 f6 py-4 d-sm-flex flex-justify-between flex-row-reverse flex-items-center border-top">
|
||
<ul class="list-style-none d-flex flex-items-center mb-3 mb-sm-0 lh-condensed-ultra">
|
||
<li class="mr-3">
|
||
<a href="https://twitter.com/github" title="GitHub on Twitter" style="color: #959da5;">
|
||
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 273.5 222.3" class="d-block" height="18">
|
||
<path
|
||
d="M273.5 26.3a109.77 109.77 0 0 1-32.2 8.8 56.07 56.07 0 0 0 24.7-31 113.39 113.39 0 0 1-35.7 13.6 56.1 56.1 0 0 0-97 38.4 54 54 0 0 0 1.5 12.8A159.68 159.68 0 0 1 19.1 10.3a56.12 56.12 0 0 0 17.4 74.9 56.06 56.06 0 0 1-25.4-7v.7a56.11 56.11 0 0 0 45 55 55.65 55.65 0 0 1-14.8 2 62.39 62.39 0 0 1-10.6-1 56.24 56.24 0 0 0 52.4 39 112.87 112.87 0 0 1-69.7 24 119 119 0 0 1-13.4-.8 158.83 158.83 0 0 0 86 25.2c103.2 0 159.6-85.5 159.6-159.6 0-2.4-.1-4.9-.2-7.3a114.25 114.25 0 0 0 28.1-29.1"
|
||
fill="currentColor"></path>
|
||
</svg>
|
||
</a>
|
||
</li>
|
||
<li class="mr-3">
|
||
<a href="https://www.facebook.com/GitHub" title="GitHub on Facebook" style="color: #959da5;">
|
||
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 15.3 15.4" class="d-block" height="18">
|
||
<path
|
||
d="M14.5 0H.8a.88.88 0 0 0-.8.9v13.6a.88.88 0 0 0 .8.9h7.3v-6h-2V7.1h2V5.4a2.87 2.87 0 0 1 2.5-3.1h.5a10.87 10.87 0 0 1 1.8.1v2.1h-1.3c-1 0-1.1.5-1.1 1.1v1.5h2.3l-.3 2.3h-2v5.9h3.9a.88.88 0 0 0 .9-.8V.8a.86.86 0 0 0-.8-.8z"
|
||
fill="currentColor"></path>
|
||
</svg>
|
||
</a>
|
||
</li>
|
||
<li class="mr-3">
|
||
<a href="https://www.youtube.com/github" title="GitHub on YouTube" style="color: #959da5;">
|
||
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 19.17 13.6" class="d-block" height="16">
|
||
<path
|
||
d="M18.77 2.13A2.4 2.4 0 0 0 17.09.42C15.59 0 9.58 0 9.58 0a57.55 57.55 0 0 0-7.5.4A2.49 2.49 0 0 0 .39 2.13 26.27 26.27 0 0 0 0 6.8a26.15 26.15 0 0 0 .39 4.67 2.43 2.43 0 0 0 1.69 1.71c1.52.42 7.5.42 7.5.42a57.69 57.69 0 0 0 7.51-.4 2.4 2.4 0 0 0 1.68-1.71 25.63 25.63 0 0 0 .4-4.67 24 24 0 0 0-.4-4.69zM7.67 9.71V3.89l5 2.91z"
|
||
fill="currentColor"></path>
|
||
</svg>
|
||
</a>
|
||
</li>
|
||
<li class="mr-3 flex-self-start">
|
||
<a href="https://www.linkedin.com/company/github" title="GitHub on Linkedin" style="color: #959da5;">
|
||
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 19 18" class="d-block" height="18">
|
||
<path
|
||
d="M3.94 2A2 2 0 1 1 2 0a2 2 0 0 1 1.94 2zM4 5.48H0V18h4zm6.32 0H6.34V18h3.94v-6.57c0-3.66 4.77-4 4.77 0V18H19v-7.93c0-6.17-7.06-5.94-8.72-2.91z"
|
||
fill="currentColor"></path>
|
||
</svg>
|
||
</a>
|
||
</li>
|
||
<li>
|
||
<a href="https://github.com/github" title="GitHub's organization" style="color: #959da5;">
|
||
<svg version="1.1" width="20" height="20" viewBox="0 0 16 16" class="octicon octicon-mark-github"
|
||
aria-hidden="true">
|
||
<path fill-rule="evenodd"
|
||
d="M8 0C3.58 0 0 3.58 0 8c0 3.54 2.29 6.53 5.47 7.59.4.07.55-.17.55-.38 0-.19-.01-.82-.01-1.49-2.01.37-2.53-.49-2.69-.94-.09-.23-.48-.94-.82-1.13-.28-.15-.68-.52-.01-.53.63-.01 1.08.58 1.23.82.72 1.21 1.87.87 2.33.66.07-.52.28-.87.51-1.07-1.78-.2-3.64-.89-3.64-3.95 0-.87.31-1.59.82-2.15-.08-.2-.36-1.02.08-2.12 0 0 .67-.21 2.2.82.64-.18 1.32-.27 2-.27.68 0 1.36.09 2 .27 1.53-1.04 2.2-.82 2.2-.82.44 1.1.16 1.92.08 2.12.51.56.82 1.27.82 2.15 0 3.07-1.87 3.75-3.65 3.95.29.25.54.73.54 1.48 0 1.07-.01 1.93-.01 2.2 0 .21.15.46.55.38A8.013 8.013 0 0016 8c0-4.42-3.58-8-8-8z">
|
||
</path>
|
||
</svg>
|
||
</a>
|
||
</li>
|
||
</ul>
|
||
<ul class="list-style-none d-flex text-gray">
|
||
<li class="mr-3">©
|
||
<script type="text/javascript">document.write(new Date().getFullYear());</script> GitHub, Inc.</li>
|
||
<li class="mr-3"><a
|
||
href="https://docs.github.com/github/site-policy/github-terms-of-service"
|
||
class="link-gray">Terms </a></li>
|
||
<li><a href="https://docs.github.com/github/site-policy/github-privacy-statement"
|
||
class="link-gray">Privacy </a></li>
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
</main>
|
||
|
||
<script type="text/javascript">
|
||
$(document).ready(function () {
|
||
$(".toggle > *").hide();
|
||
$(".toggle .name").show();
|
||
$(".toggle .name").click(function () {
|
||
$(this).parent().children().not(".name").toggle(400);
|
||
$(this).parent().children(".name").toggleClass("open");
|
||
})
|
||
});
|
||
</script>
|
||
|
||
</body>
|
||
</html> |