360 lines
16 KiB
HTML
360 lines
16 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
|
|
"http://www.w3.org/TR/html4/strict.dtd">
|
|
<html>
|
|
<head>
|
|
<title>scan-build: running the analyzer from the command line</title>
|
|
<link type="text/css" rel="stylesheet" href="content.css">
|
|
<link type="text/css" rel="stylesheet" href="menu.css">
|
|
<script type="text/javascript" src="scripts/menu.js"></script>
|
|
<script type="text/javascript" src="scripts/dbtree.js"></script>
|
|
</head>
|
|
<body>
|
|
|
|
<div id="page">
|
|
<!--#include virtual="menu.html.incl"-->
|
|
<div id="content">
|
|
|
|
<h1>scan-build: running the analyzer from the command line</h1>
|
|
|
|
<table style="margin-top:0px" width="100%" cellpadding="0px" cellspacing="0">
|
|
<tr><td>
|
|
|
|
<h3>What is it?</h3>
|
|
<p><b>scan-build</b> is a command line utility that enables a user to run the
|
|
static analyzer over their codebase as part of performing a regular build (from
|
|
the command line).</p>
|
|
|
|
<h3>How does it work?</h3>
|
|
<p>During a project build, as source files are compiled they are also analyzed
|
|
in tandem by the static analyzer.</p>
|
|
|
|
<p>Upon completion of the build, results are then presented to the user within a
|
|
web browser.</p>
|
|
|
|
<h3>Will it work with any build system?</h3>
|
|
<p><b>scan-build</b> has little or no knowledge about how you build your code.
|
|
It works by overriding the <tt>CC</tt> and <tt>CXX</tt> environment variables to
|
|
(hopefully) change your build to use a "fake" compiler instead of the
|
|
one that would normally build your project. This fake compiler executes either
|
|
<tt>clang</tt> or <tt>gcc</tt> (depending on the platform) to compile your
|
|
code and then executes the static analyzer to analyze your code.</p>
|
|
|
|
<p>This "poor man's interposition" works amazingly well in many cases
|
|
and falls down in others. Please consult the information on this page on making
|
|
the best use of <b>scan-build</b>, which includes getting it to work when the
|
|
aforementioned hack fails to work.</p>
|
|
|
|
</td>
|
|
<td style="padding-left:10px; text-align:center">
|
|
<img src="images/scan_build_cmd.png" width="450px" alt="scan-build"><br>
|
|
<a href="images/analyzer_html.png"><img src="images/analyzer_html.png" width="450px" alt="analyzer in browser"></a>
|
|
<br><b>Viewing static analyzer results in a web browser</b>
|
|
</td></tr></table>
|
|
|
|
<h2>Contents</h2>
|
|
|
|
<ul id="collapsetree" class="dbtree onclick multiple">
|
|
<li><a href="#scanbuild">Getting Started</a>
|
|
<ul>
|
|
<li><a href="#scanbuild_basicusage">Basic Usage</a></li>
|
|
<li><a href="#scanbuild_forwindowsusers">For Windows Users</a></li>
|
|
<li><a href="#scanbuild_otheroptions">Other Options</a></li>
|
|
<li><a href="#scanbuild_output">Output of scan-build</a></li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="#recommendedguidelines">Recommended Usage Guidelines</a>
|
|
<ul>
|
|
<li><a href="#recommended_debug">Always Analyze a Project in its "Debug" Configuration</a></li>
|
|
<li><a href="#recommended_verbose">Use Verbose Output when Debugging scan-build</a></li>
|
|
<li><a href="#recommended_autoconf">Run './configure' through scan-build</a></li>
|
|
</ul>
|
|
</li>
|
|
<li><a href="#iphone">Analyzing iPhone Projects</a></li>
|
|
</ul>
|
|
|
|
<h2 id="scanbuild">Getting Started</h2>
|
|
|
|
<p>The <tt>scan-build</tt> command can be used to analyze an entire project by
|
|
essentially interposing on a project's build process. This means that to run the
|
|
analyzer using <tt>scan-build</tt>, you will use <tt>scan-build</tt> to analyze
|
|
the source files compiled by <tt>gcc</tt>/<tt>clang</tt> during a project build.
|
|
This means that any files that are not compiled will also not be analyzed.</p>
|
|
|
|
<h3 id="scanbuild_basicusage">Basic Usage</h3>
|
|
|
|
<p>Basic usage of <tt>scan-build</tt> is designed to be simple: just place the
|
|
word "scan-build" in front of your build command:</p>
|
|
|
|
<pre class="code_example">
|
|
$ <span class="code_highlight">scan-build</span> make
|
|
$ <span class="code_highlight">scan-build</span> xcodebuild
|
|
</pre>
|
|
|
|
<p>In the first case <tt>scan-build</tt> analyzes the code of a project built
|
|
with <tt>make</tt> and in the second case <tt>scan-build</tt> analyzes a project
|
|
built using <tt>xcodebuild</tt>.<p>
|
|
|
|
<p>Here is the general format for invoking <tt>scan-build</tt>:</p>
|
|
|
|
<pre class="code_example">
|
|
$ <span class="code_highlight">scan-build</span> <i>[scan-build options]</i> <span class="code_highlight"><command></span> <i>[command options]</i>
|
|
</pre>
|
|
|
|
<p>Operationally, <tt>scan-build</tt> literally runs <command> with all of the
|
|
subsequent options passed to it. For example, one can pass <tt>-j4</tt> to
|
|
<tt>make</tt> get a parallel build over 4 cores:</p>
|
|
|
|
<pre class="code_example">
|
|
$ scan-build make <span class="code_highlight">-j4</span>
|
|
</pre>
|
|
|
|
<p>In almost all cases, <tt>scan-build</tt> makes no effort to interpret the
|
|
options after the build command; it simply passes them through. In general,
|
|
<tt>scan-build</tt> should support parallel builds, but <b>not distributed
|
|
builds</b>.</p>
|
|
|
|
<p>It is also possible to use <tt>scan-build</tt> to analyze specific
|
|
files:</p>
|
|
|
|
<pre class="code_example">
|
|
$ scan-build gcc -c <span class="code_highlight">t1.c t2.c</span>
|
|
</pre>
|
|
|
|
<p>This example causes the files <tt>t1.c</tt> and <tt>t2.c</tt> to be analyzed.
|
|
</p>
|
|
|
|
<h3 id="scanbuild_forwindowsusers">For Windows Users</h3>
|
|
|
|
<p>Windows users must have Perl installed to use scan-build. Currently scan-build
|
|
is known to work with the msys perl port.</p>
|
|
|
|
<p>scan-build.bat script allows you to launch scan-build in the same way as it described in the Basic Usage section above.
|
|
All you need to be able to invoke scan-build from an arbitrary location is to add the path to scan-build to your PATH environment variable.</p>
|
|
|
|
<h3 id="scanbuild_otheroptions">Other Options</h3>
|
|
|
|
<p>As mentioned above, extra options can be passed to <tt>scan-build</tt>. These
|
|
options prefix the build command. For example:</p>
|
|
|
|
<pre class="code_example">
|
|
$ scan-build <span class="code_highlight">-k -V</span> make
|
|
$ scan-build <span class="code_highlight">-k -V</span> xcodebuild
|
|
</pre>
|
|
|
|
<p>Here is a subset of useful options:</p>
|
|
|
|
<table class="options">
|
|
<colgroup><col class="option"><col class="description"></colgroup>
|
|
<thead><tr><td>Option</td><td>Description</td></tr></thead>
|
|
|
|
<tr><td><b>-o</b></td><td>Target directory for HTML report files. Subdirectories
|
|
will be created as needed to represent separate "runs" of the analyzer. If this
|
|
option is not specified, a directory is created in <tt>/tmp</tt> to store the
|
|
reports.</td></tr>
|
|
|
|
<tr><td><b>-h</b><br><i>(or no arguments)</i></td><td>Display all
|
|
<tt>scan-build</tt> options.</td></tr>
|
|
|
|
<tr><td><b>-k</b><br><b>--keep-going</b></td><td>Add a "keep on
|
|
going" option to the specified build command. <p>This option currently supports
|
|
<tt>make</tt> and <tt>xcodebuild</tt>.</p> <p>This is a convenience option; one
|
|
can specify this behavior directly using build options.</p></td></tr>
|
|
|
|
<tr><td><b>-v</b></td><td>Verbose output from scan-build and the analyzer. <b>A
|
|
second and third "-v" increases verbosity</b>, and is useful for filing bug
|
|
reports against the analyzer.</td></tr>
|
|
|
|
<tr><td><b>-V</b></td><td>View analysis results in a web browser when the build
|
|
command completes.</td></tr>
|
|
|
|
<tr><td><b>--use-analyzer Xcode</b><br><i>or</i><br>
|
|
<b>--use-analyzer [path to clang]</b></td><td><tt>scan-build</tt> uses the
|
|
'clang' executable relative to itself for static analysis. One can override this
|
|
behavior with this option by using the 'clang' packaged with Xcode (on OS X) or
|
|
from the PATH.</p></td></tr> </table>
|
|
|
|
<p>A complete list of options can be obtained by running <tt>scan-build</tt>
|
|
with no arguments.</p>
|
|
|
|
<h3 id="scanbuild_output">Output of scan-build</h3>
|
|
|
|
<p>
|
|
The output of scan-build is a set of HTML files, each one which represents a
|
|
separate bug report. A single <tt>index.html</tt> file is generated for
|
|
surveying all of the bugs. You can then just open <tt>index.html</tt> in a web
|
|
browser to view the bug reports.
|
|
</p>
|
|
|
|
<p>
|
|
Where the HTML files are generated is specified with a <b>-o</b> option to
|
|
<tt>scan-build</tt>. If <b>-o</b> isn't specified, a directory in <tt>/tmp</tt>
|
|
is created to store the files (<tt>scan-build</tt> will print a message telling
|
|
you where they are). If you want to view the reports immediately after the build
|
|
completes, pass <b>-V</b> to <tt>scan-build</tt>.
|
|
</p>
|
|
|
|
|
|
<h2 id="recommendedguidelines">Recommended Usage Guidelines</h2>
|
|
|
|
<p>This section describes a few recommendations with running the analyzer.</p>
|
|
|
|
<h3 id="recommended_debug">ALWAYS analyze a project in its "debug" configuration</h3>
|
|
|
|
<p>Most projects can be built in a "debug" mode that enables assertions.
|
|
Assertions are picked up by the static analyzer to prune infeasible paths, which
|
|
in some cases can greatly reduce the number of false positives (bogus error
|
|
reports) emitted by the tool.</p>
|
|
|
|
<h3 id="recommend_verbose">Use verbose output when debugging scan-build</h3>
|
|
|
|
<p><tt>scan-build</tt> takes a <b>-v</b> option to emit verbose output about
|
|
what it's doing; two <b>-v</b> options emit more information. Redirecting the
|
|
output of <tt>scan-build</tt> to a text file (make sure to redirect standard
|
|
error) is useful for filing bug reports against <tt>scan-build</tt> or the
|
|
analyzer, as we can see the exact options (and files) passed to the analyzer.
|
|
For more comprehensible logs, don't perform a parallel build.</p>
|
|
|
|
<h3 id="recommended_autoconf">Run './configure' through scan-build</h3>
|
|
|
|
<p>If an analyzed project uses an autoconf generated <tt>configure</tt> script,
|
|
you will probably need to run <tt>configure</tt> script through
|
|
<tt>scan-build</tt> in order to analyze the project.</p>
|
|
|
|
<p><b>Example</b></p>
|
|
|
|
<pre class="code_example">
|
|
$ scan-build ./configure
|
|
$ scan-build make
|
|
</pre>
|
|
|
|
<p>The reason <tt>configure</tt> also needs to be run through
|
|
<tt>scan-build</tt> is because <tt>scan-build</tt> scans your source files by
|
|
<i>interposing</i> on the compiler. This interposition is currently done by
|
|
<tt>scan-build</tt> temporarily setting the environment variable <tt>CC</tt> to
|
|
<tt>ccc-analyzer</tt>. The program <tt>ccc-analyzer</tt> acts like a fake
|
|
compiler, forwarding its command line arguments over to the compiler to perform
|
|
regular compilation and <tt>clang</tt> to perform static analysis.</p>
|
|
|
|
<p>Running <tt>configure</tt> typically generates makefiles that have hardwired
|
|
paths to the compiler, and by running <tt>configure</tt> through
|
|
<tt>scan-build</tt> that path is set to <tt>ccc-analyzer</tt>.</p>
|
|
|
|
<!--
|
|
<h2 id="Debugging">Debugging the Analyzer</h2>
|
|
|
|
<p>This section provides information on debugging the analyzer, and troubleshooting
|
|
it when you have problems analyzing a particular project.</p>
|
|
|
|
<h3>How it Works</h3>
|
|
|
|
<p>To analyze a project, <tt>scan-build</tt> simply sets the environment variable
|
|
<tt>CC</tt> to the full path to <tt>ccc-analyzer</tt>. It also sets a few other
|
|
environment variables to communicate to <tt>ccc-analyzer</tt> where to dump HTML
|
|
report files.</p>
|
|
|
|
<p>Some Makefiles (or equivalent project files) hardcode the compiler; for such
|
|
projects simply overriding <tt>CC</tt> won't cause <tt>ccc-analyzer</tt> to be
|
|
called. This will cause the compiled code <b>to not be analyzed.</b></p> If you
|
|
find that your code isn't being analyzed, check to see if <tt>CC</tt> is
|
|
hardcoded. If this is the case, you can hardcode it instead to the <b>full
|
|
path</b> to <tt>ccc-analyzer</tt>.</p>
|
|
|
|
<p>When applicable, you can also run <tt>./configure</tt> for a project through
|
|
<tt>scan-build</tt> so that configure sets up the location of <tt>CC</tt> based
|
|
on the environment passed in from <tt>scan-build</tt>:
|
|
|
|
<pre>
|
|
$ scan-build <b>./configure</b>
|
|
</pre>
|
|
|
|
<p><tt>scan-build</tt> has special knowledge about <tt>configure</tt>, so it in
|
|
most cases will not actually analyze the configure tests run by
|
|
<tt>configure</tt>.</p>
|
|
|
|
<p>Under the hood, <tt>ccc-analyzer</tt> directly invokes <tt>gcc</tt> to
|
|
compile the actual code in addition to running the analyzer (which occurs by it
|
|
calling <tt>clang</tt>). <tt>ccc-analyzer</tt> tries to correctly forward all
|
|
the arguments over to <tt>gcc</tt>, but this may not work perfectly (please
|
|
report bugs of this kind).
|
|
-->
|
|
|
|
<h2 id="iphone">Analyzing iPhone Projects</h2>
|
|
|
|
<p>Conceptually Xcode projects for iPhone applications are nearly the same as
|
|
their cousins for desktop applications. <b>scan-build</b> can analyze these
|
|
projects as well, but users often encounter problems with just building their
|
|
iPhone projects from the command line because there are a few extra preparative
|
|
steps they need to take (e.g., setup code signing).</p>
|
|
|
|
<h3>Recommendation: use "Build and Analyze"</h3>
|
|
|
|
<p>The absolute easiest way to analyze iPhone projects is to use the <a
|
|
href="http://developer.apple.com/mac/library/featuredarticles/StaticAnalysis/index.html"><i>Build
|
|
and Analyze</i> feature in Xcode 3.2</a> (which is based on the Clang Static
|
|
Analyzer). There a user can analyze their project with the click of a button
|
|
without most of the setup described later.</p>
|
|
|
|
<p><a href="/xcode.html">Instructions are available</a> on this
|
|
website on how to use open source builds of the analyzer as a replacement for
|
|
the one bundled with Xcode.</p>
|
|
|
|
<h3>Using scan-build directly</h3>
|
|
|
|
<p>If you wish to use <b>scan-build</b> with your iPhone project, keep the
|
|
following things in mind:</p>
|
|
|
|
<ul>
|
|
<li>Analyze your project in the <tt>Debug</tt> configuration, either by setting
|
|
this as your configuration with Xcode or by passing <tt>-configuration
|
|
Debug</tt> to <tt>xcodebuild</tt>.</li>
|
|
<li>Analyze your project using the <tt>Simulator</tt> as your base SDK. It is
|
|
possible to analyze your code when targeting the device, but this is much
|
|
easier to do when using Xcode's <i>Build and Analyze</i> feature.</li>
|
|
<li>Check that your code signing SDK is set to the simulator SDK as well, and make sure this option is set to <tt>Don't Code Sign</tt>.</li>
|
|
</ul>
|
|
|
|
<p>Note that you can most of this without actually modifying your project. For
|
|
example, if your application targets iPhoneOS 2.2, you could run
|
|
<b>scan-build</b> in the following manner from the command line:</p>
|
|
|
|
<pre class="code_example">
|
|
$ scan-build xcodebuild -configuration Debug -sdk iphonesimulator2.2
|
|
</pre>
|
|
|
|
Alternatively, if your application targets iPhoneOS 3.0:
|
|
|
|
<pre class="code_example">
|
|
$ scan-build xcodebuild -configuration Debug -sdk iphonesimulator3.0
|
|
</pre>
|
|
|
|
<h3>Gotcha: using the right compiler</h3>
|
|
|
|
<p>Recall that <b>scan-build</b> analyzes your project by using a compiler to
|
|
compile the project and <tt>clang</tt> to analyze your project. The script uses
|
|
simple heuristics to determine which compiler should be used (it defaults to
|
|
<tt>clang</tt> on Darwin and <tt>gcc</tt> on other platforms). When analyzing
|
|
iPhone projects, <b>scan-build</b> may pick the wrong compiler than the one
|
|
Xcode would use to build your project. For example, this could be because
|
|
multiple versions of a compiler may be installed on your system, especially if
|
|
you are developing for the iPhone.</p>
|
|
|
|
<p>When compiling your application to run on the simulator, it is important that <b>scan-build</b>
|
|
finds the correct version of <tt>gcc/clang</tt>. Otherwise, you may see strange build
|
|
errors that only happen when you run <tt>scan-build</tt>.
|
|
|
|
<p><b>scan-build</b> provides the <tt>--use-cc</tt> and <tt>--use-c++</tt>
|
|
options to hardwire which compiler scan-build should use for building your code.
|
|
Note that although you are chiefly interested in analyzing your project, keep in
|
|
mind that running the analyzer is intimately tied to the build, and not being
|
|
able to compile your code means it won't get fully analyzed (if at all).</p>
|
|
|
|
<p>If you aren't certain which compiler Xcode uses to build your project, try
|
|
just running <tt>xcodebuild</tt> (without <b>scan-build</b>). You should see the
|
|
full path to the compiler that Xcode is using, and use that as an argument to
|
|
<tt>--use-cc</tt>.</p>
|
|
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|
|
|