1229 lines
38 KiB
XML
1229 lines
38 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
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<book>
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<bookinfo>
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<title>Cppcheck 1.68 dev</title>
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<date>2014-09-28</date>
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</bookinfo>
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<chapter>
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<title>Introduction</title>
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<para>Cppcheck is an analysis tool for C/C++ code. Unlike C/C++ compilers
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and many other analysis tools, it doesn't detect syntax errors. Cppcheck
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only detects the types of bugs that the compilers normally fail to detect.
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The goal is no false positives.</para>
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<para>Supported code and platforms:</para>
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<itemizedlist>
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<listitem>
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<para>You can check non-standard code that includes various compiler
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extensions, inline assembly code, etc.</para>
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</listitem>
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<listitem>
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<para>Cppcheck should be compilable by any C++ compiler that handles
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the latest C++ standard.</para>
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</listitem>
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<listitem>
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<para>Cppcheck should work on any platform that has sufficient CPU and
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memory.</para>
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</listitem>
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</itemizedlist>
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<para>Accuracy</para>
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<para>Please understand that there are limits of Cppcheck. Cppcheck is
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rarely wrong about reported errors. But there are many bugs that it
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doesn't detect.</para>
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<para>You will find more bugs in your software by testing your software
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carefully, than by using Cppcheck. You will find more bugs in your
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software by instrumenting your software, than by using Cppcheck. But
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Cppcheck can still detect some of the bugs that you miss when testing and
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instrumenting your software.</para>
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</chapter>
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<chapter>
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<title>Getting started</title>
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<section>
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<title>First test</title>
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<para>Here is a simple code</para>
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<programlisting>int main()
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{
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char a[10];
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a[10] = 0;
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return 0;
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}</programlisting>
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<para>If you save that into <filename>file1.c</filename> and
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execute:</para>
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<programlisting>cppcheck file1.c</programlisting>
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<para>The output from cppcheck will then be:</para>
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<programlisting>Checking file1.c...
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[file1.c:4]: (error) Array 'a[10]' index 10 out of bounds</programlisting>
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</section>
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<section>
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<title>Checking all files in a folder</title>
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<para>Normally a program has many source files. And you want to check
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them all. Cppcheck can check all source files in a directory:</para>
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<programlisting>cppcheck path</programlisting>
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<para>If "path" is a folder then cppcheck will check all source files in
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this folder.</para>
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<programlisting>Checking path/file1.cpp...
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1/2 files checked 50% done
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Checking path/file2.cpp...
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2/2 files checked 100% done</programlisting>
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</section>
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<section>
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<title>Excluding a file or folder from checking</title>
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<para>To exclude a file or folder, there are two options.</para>
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<para>The first option is to only provide the paths and files you want
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to check.</para>
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<programlisting>cppcheck src/a src/b</programlisting>
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<para>All files under <filename class="directory">src/a</filename> and
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<filename class="directory">src/b</filename> are then checked.</para>
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<para>The second option is to use <parameter
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class="command">-i</parameter>, with it you specify files/paths to
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ignore. With this command no files in <filename
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class="directory">src/c</filename> are checked:</para>
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<programlisting>cppcheck -isrc/c src</programlisting>
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</section>
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<section>
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<title>Severities</title>
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<para>The possible severities for messages are:</para>
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<variablelist>
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<varlistentry>
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<term>error</term>
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<listitem>
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<para>used when bugs are found</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>warning</term>
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<listitem>
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<para>suggestions about defensive programming to prevent
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bugs</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>style</term>
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<listitem>
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<para>stylistic issues related to code cleanup (unused functions,
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redundant code, constness, and such)</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>performance</term>
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<listitem>
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<para>Suggestions for making the code faster. These suggestions
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are only based on common knowledge. It is not certain you'll get
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any measurable difference in speed by fixing these
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messages.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>portability</term>
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<listitem>
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<para>portability warnings. 64-bit portability. code might work
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different on different compilers. etc.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>information</term>
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<listitem>
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<para>Informational messages about checking problems.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section>
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<title>Enable messages</title>
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<para>By default only <parameter class="command">error</parameter>
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messages are shown. Through the <parameter
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class="command">--enable</parameter> command more checks can be
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enabled.</para>
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<programlisting># enable warning messages
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cppcheck --enable=warning file.c
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# enable performance messages
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cppcheck --enable=performance file.c
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# enable information messages
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cppcheck --enable=information file.c
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# For historical reasons, --enable=style enables warning, performance,
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# portability and style messages. These are all reported as "style" when
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# using the old xml format.
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cppcheck --enable=style file.c
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# enable warning and information messages
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cppcheck --enable=warning,information file.c
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# enable unusedFunction checking. This is not enabled by --enable=style
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# because it doesn't work well on libraries.
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cppcheck --enable=unusedFunction file.c
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# enable all messages
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cppcheck --enable=all</programlisting>
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<para>Please note that <literal>--enable=unusedFunction</literal> should
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only be used when the whole program is scanned. And therefore
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<literal>--enable=all</literal> should also only be used when the whole
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program is scanned. The reason is that the unusedFunction checking will
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warn if a function is not called. There will be noise if function calls
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are not seen.</para>
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<section>
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<title>Inconclusive checks</title>
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<para>By default Cppcheck only writes error messages if it is certain.
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With <parameter class="command">--inconclusive</parameter> error
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messages will also be written when the analysis is
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inconclusive.</para>
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<programlisting>cppcheck --inconclusive path</programlisting>
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<para>This can of course cause false warnings, it might be reported
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that there are bugs even though there are not. Only use this command
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if false warnings are acceptable.</para>
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</section>
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</section>
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<section>
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<title>Saving results in file</title>
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<para>Many times you will want to save the results in a file. You can
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use the normal shell redirection for piping error output to a
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file.</para>
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<programlisting>cppcheck file1.c 2> err.txt</programlisting>
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</section>
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<section>
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<title>Multithreaded checking</title>
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<para>The option -j is used to specify the number of threads you want to
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use. For example, to use 4 threads to check the files in a
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folder:</para>
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<programlisting>cppcheck -j 4 path</programlisting>
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</section>
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</chapter>
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<chapter id="preprocessor-configurations">
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<title>Preprocessor configurations</title>
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<para>By default Cppcheck will check all preprocessor configurations
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(except those that have #error in them).</para>
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<para>You can use -D to change this. When you use -D, cppcheck will by
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default only check the given configuration and nothing else. This is how
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compilers work. But you can use <literal>--force</literal> or
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<literal><literal>--max-configs</literal></literal> to override the number
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of configurations.</para>
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<programlisting># check all configurations
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cppcheck file.c
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# only check the configuration A
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cppcheck -DA file.c
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# check all configurations when macro A is defined
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cppcheck -DA --force file.c</programlisting>
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<para>Another useful flag might be -U. It undefines a symbol. Example
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usage:</para>
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<programlisting>cppcheck -UX file.c</programlisting>
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<para>That will mean that X is not defined. Cppcheck will not check what
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happens when X is defined.</para>
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</chapter>
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<chapter>
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<title>XML output</title>
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<para>Cppcheck can generate the output in <literal>XML</literal> format.
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There is an old <literal>XML</literal> format (version 1) and a new
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<literal>XML</literal> format (version 2). Please use the new version if
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you can.</para>
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<para>The old version is kept for backwards compatibility only. It will
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not be changed. But it will likely be removed someday. Use
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<parameter>--xml</parameter> to enable this format.</para>
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<para>The new version fixes a few problems with the old format. The new
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format will probably be updated in future versions of cppcheck with new
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attributes and elements. A sample command to check a file and output
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errors in the new <literal>XML</literal> format:</para>
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<para><programlisting>cppcheck --xml-version=2 file1.cpp</programlisting>Here
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is a sample version 2 report:</para>
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<programlisting><?xml version="1.0" encoding="UTF-8"?>
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<results version="2">
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<cppcheck version="1.66">
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<errors>
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<error id="someError" severity="error" msg="short error text"
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verbose="long error text" inconclusive="true">
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<location file="file.c" line="1"/>
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</error>
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</errors>
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</results></programlisting>
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<section>
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<title>The <error> element</title>
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<para>Each error is reported in a <literal><error></literal>
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element. Attributes:</para>
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<variablelist>
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<varlistentry>
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<term><sgmltag class="attribute">id</sgmltag></term>
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<listitem>
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<para>id of error. These are always valid symbolnames.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><sgmltag class="attribute">severity</sgmltag></term>
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<listitem>
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<para>either: <literal>error</literal>,
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<literal>warning</literal>, <literal>style</literal>,
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<literal>performance</literal>, <literal>portability</literal> or
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<literal>information</literal></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><sgmltag class="attribute">msg</sgmltag></term>
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<listitem>
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<para>the error message in short format</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><sgmltag>verbose</sgmltag></term>
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<listitem>
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<para>the error message in long format.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><sgmltag>inconclusive</sgmltag></term>
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<listitem>
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<para>This attribute is only used when the message is
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inconclusive.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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<section>
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<title>The <location> element</title>
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<para>All locations related to an error is listed with
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<literal><location></literal> elements. The primary location is
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listed first.</para>
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<para>Attributes:</para>
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<variablelist>
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<varlistentry>
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<term><sgmltag class="attribute">file</sgmltag></term>
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<listitem>
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<para>filename. Both relative and absolute paths are
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possible</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><sgmltag class="attribute">line</sgmltag></term>
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<listitem>
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<para>a number</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><sgmltag>msg</sgmltag></term>
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<listitem>
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<para>this attribute doesn't exist yet. But in the future we may
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add a short message for each location.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</section>
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</chapter>
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<chapter>
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<title>Reformatting the output</title>
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<para>If you want to reformat the output so it looks different you can use
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templates.</para>
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<para>To get Visual Studio compatible output you can use <parameter
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class="command">--template=vs</parameter>:</para>
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<programlisting>cppcheck --template=vs gui/test.cpp</programlisting>
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<para>This output will look like this:</para>
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<programlisting>Checking gui/test.cpp...
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gui/test.cpp(31): error: Memory leak: b
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gui/test.cpp(16): error: Mismatching allocation and deallocation: k</programlisting>
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<para>To get gcc compatible output you can use <parameter
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class="command">--template=gcc</parameter>:</para>
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<programlisting>cppcheck --template=gcc gui/test.cpp</programlisting>
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<para>The output will look like this:</para>
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<programlisting>Checking gui/test.cpp...
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gui/test.cpp:31: error: Memory leak: b
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gui/test.cpp:16: error: Mismatching allocation and deallocation: k</programlisting>
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<para>You can write your own pattern (for example a comma-separated
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format):</para>
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<programlisting>cppcheck --template="{file},{line},{severity},{id},{message}" gui/test.cpp</programlisting>
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<para>The output will look like this:</para>
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<programlisting>Checking gui/test.cpp...
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gui/test.cpp,31,error,memleak,Memory leak: b
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gui/test.cpp,16,error,mismatchAllocDealloc,Mismatching allocation and deallocation: k</programlisting>
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<para>The following format specifiers are supported:</para>
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<variablelist>
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<varlistentry>
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<term>callstack</term>
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<listitem>
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<para>callstack - if available</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>file</term>
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<listitem>
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<para>filename</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>id</term>
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<listitem>
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<para>message id</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>line</term>
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<listitem>
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<para>line number</para>
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</listitem>
|
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</varlistentry>
|
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<varlistentry>
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<term>message</term>
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<listitem>
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<para>verbose message text</para>
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</listitem>
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</varlistentry>
|
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|
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<varlistentry>
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<term>severity</term>
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|
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<listitem>
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<para>severity</para>
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</listitem>
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</varlistentry>
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</variablelist>
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|
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<para>The escape sequences \b (backspace), \n (newline), \r (formfeed) and
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\t (horizontal tab) are supported.</para>
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</chapter>
|
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|
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<chapter>
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|
<title>Suppressions</title>
|
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|
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<para>If you want to filter out certain errors you can suppress
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these.</para>
|
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|
|
<section>
|
|
<title>Suppressing a certain error type</title>
|
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|
|
<para>You can suppress certain types of errors. The format for such a
|
|
suppression is one of:</para>
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|
|
<programlisting>[error id]:[filename]:[line]
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|
[error id]:[filename2]
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|
[error id]</programlisting>
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|
|
|
<para>The <replaceable>error id</replaceable> is the id that you want to
|
|
suppress. The easiest way to get it is to use the <parameter
|
|
class="command">--xml</parameter> command line flag. Copy and paste the
|
|
<replaceable>id</replaceable> string from the XML output. This may be
|
|
<literal>*</literal> to suppress all warnings (for a specified file or
|
|
files).</para>
|
|
|
|
<para>The <replaceable>filename</replaceable> may include the wildcard
|
|
characters <literal>*</literal> or <literal>?</literal>, which match any
|
|
sequence of characters or any single character respectively. It is
|
|
recommended that you use "/" as path separator on all operating
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|
systems.</para>
|
|
|
|
<section>
|
|
<title>Command line suppression</title>
|
|
|
|
<para>The <parameter class="command">--suppress=</parameter> command
|
|
line option is used to specify suppressions on the command line.
|
|
Example:</para>
|
|
|
|
<programlisting>cppcheck --suppress=memleak:src/file1.cpp src/</programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Listing suppressions in a file</title>
|
|
|
|
<para>You can create a suppressions file. Example:</para>
|
|
|
|
<programlisting>// suppress memleak and exceptNew errors in the file src/file1.cpp
|
|
memleak:src/file1.cpp
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|
exceptNew:src/file1.cpp
|
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|
|
// suppress all uninitvar errors in all files
|
|
uninitvar</programlisting>
|
|
|
|
<para>Note that you may add empty lines and comments in the
|
|
suppressions file.</para>
|
|
|
|
<para>You can use the suppressions file like this:</para>
|
|
|
|
<programlisting>cppcheck --suppressions suppressions.txt src/</programlisting>
|
|
</section>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Inline suppressions</title>
|
|
|
|
<para>Suppressions can also be added directly in the code by adding
|
|
comments that contain special keywords. Before adding such comments,
|
|
consider that the code readability is sacrificed a little.</para>
|
|
|
|
<para>This code will normally generate an error message:</para>
|
|
|
|
<programlisting>void f() {
|
|
char arr[5];
|
|
arr[10] = 0;
|
|
}</programlisting>
|
|
|
|
<para>The output is:</para>
|
|
|
|
<programlisting># cppcheck test.c
|
|
Checking test.c...
|
|
[test.c:3]: (error) Array 'arr[5]' index 10 out of bounds</programlisting>
|
|
|
|
<para>To suppress the error message, a comment can be added:</para>
|
|
|
|
<programlisting>void f() {
|
|
char arr[5];
|
|
|
|
// cppcheck-suppress arrayIndexOutOfBounds
|
|
arr[10] = 0;
|
|
}</programlisting>
|
|
|
|
<para>Now the --inline-suppr flag can be used to suppress the warning.
|
|
No error is reported when invoking cppcheck this way:</para>
|
|
|
|
<programlisting>cppcheck --inline-suppr test.c</programlisting>
|
|
</section>
|
|
</chapter>
|
|
|
|
<chapter>
|
|
<title>Library configuration</title>
|
|
|
|
<para>When external libraries are used, such as windows/posix/gtk/qt/etc,
|
|
<literal>Cppcheck</literal> doesn't know how the external functions
|
|
behave. <literal>Cppcheck</literal> then fails to detect various problems
|
|
such as leaks, buffer overflows, possible null pointer dereferences, etc.
|
|
But this can be fixed with configuration files.</para>
|
|
|
|
<para>If you create a configuration file for a popular library, we would
|
|
appreciate if you upload it to us.</para>
|
|
|
|
<section>
|
|
<title>Using your own custom .cfg file</title>
|
|
|
|
<para>You can create and use your own .cfg files for your
|
|
projects.</para>
|
|
|
|
<para>The command line cppcheck will try to load custom .cfg files from
|
|
the working path - execute cppcheck from the path where the .cfg files
|
|
are.</para>
|
|
|
|
<para>The cppcheck GUI will try to load custom .cfg files from the
|
|
project file path. The custom .cfg files should be shown in the
|
|
<literal>Edit Project File</literal> dialog that you open from the
|
|
<literal>File</literal> menu.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Memory/resource leaks</title>
|
|
|
|
<para>Here is an example program:</para>
|
|
|
|
<para><programlisting>void test()
|
|
{
|
|
HPEN pen = CreatePen(PS_SOLID, 1, RGB(255,0,0));
|
|
}</programlisting></para>
|
|
|
|
<para>The code example above has a resource leak -
|
|
<literal>CreatePen()</literal> is a windows function that creates a pen.
|
|
However Cppcheck doesn't assume that return values from functions must
|
|
be freed. There is no error message:</para>
|
|
|
|
<programlisting># cppcheck pen1.c
|
|
Checking pen1.c...</programlisting>
|
|
|
|
<para>If you provide a windows configuration file then
|
|
<literal>Cppcheck</literal> detects the bug:</para>
|
|
|
|
<programlisting># cppcheck --library=windows.cfg pen1.c
|
|
Checking pen1.c...
|
|
[pen1.c:3]: (error) Resource leak: pen</programlisting>
|
|
|
|
<para>Here is a minimal <literal>windows.cfg</literal> file:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<resource>
|
|
<alloc>CreatePen</alloc>
|
|
<dealloc>DeleteObject</dealloc>
|
|
</resource>
|
|
</def></programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Function argument: Uninitialized memory</title>
|
|
|
|
<para>Here is an example program:</para>
|
|
|
|
<programlisting>void test()
|
|
{
|
|
char buffer1[1024];
|
|
char buffer2[1024];
|
|
CopyMemory(buffer1, buffer2, 1024);
|
|
}</programlisting>
|
|
|
|
<para>The bug here is that buffer2 is uninitialized. The second argument
|
|
for CopyMemory needs to be initialized. However
|
|
<literal>Cppcheck</literal> assumes that it is fine to pass
|
|
uninitialized variables to functions:</para>
|
|
|
|
<programlisting># cppcheck uninit.c
|
|
Checking uninit.c...</programlisting>
|
|
|
|
<para>If you provide a windows configuration file then Cppcheck detects
|
|
the bug:</para>
|
|
|
|
<programlisting># cppcheck --library=windows.cfg uninit.c
|
|
Checking uninit.c...
|
|
[uninit.c:5]: (error) Uninitialized variable: buffer2</programlisting>
|
|
|
|
<para>Here is the minimal <literal>windows.cfg</literal>:</para>
|
|
|
|
<para><programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<function name="CopyMemory">
|
|
<arg nr="2">
|
|
<not-uninit/>
|
|
</arg>
|
|
</function>
|
|
</def></programlisting></para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Function Argument: Null pointers</title>
|
|
|
|
<para>Cppcheck assumes it's ok to pass NULL pointers to functions. Here
|
|
is an example program:</para>
|
|
|
|
<programlisting>void test()
|
|
{
|
|
CopyMemory(NULL, NULL, 1024);
|
|
}</programlisting>
|
|
|
|
<para>The MSDN documentation is not clear if that is ok or not. But
|
|
let's assume it's bad. Cppcheck assumes that it's ok to pass NULL to
|
|
functions so no error is reported:</para>
|
|
|
|
<programlisting># cppcheck null.c
|
|
Checking null.c...</programlisting>
|
|
|
|
<para>If you provide a windows configuration file then
|
|
<literal>Cppcheck</literal> detects the bug:</para>
|
|
|
|
<programlisting>cppcheck --library=windows.cfg null.c
|
|
Checking null.c...
|
|
[null.c:3]: (error) Null pointer dereference</programlisting>
|
|
|
|
<para>Here is a minimal <literal>windows.cfg</literal> file:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<function name="CopyMemory">
|
|
<arg nr="1">
|
|
<not-null/>
|
|
</arg>
|
|
</function>
|
|
</def></programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Function Argument: Format string</title>
|
|
|
|
<para>You can define that a function takes a format string.
|
|
Example:</para>
|
|
|
|
<programlisting>void test()
|
|
{
|
|
do_something("%i %i\n", 1024);
|
|
}</programlisting>
|
|
|
|
<para>No error is reported for that:</para>
|
|
|
|
<programlisting># cppcheck formatstring.c
|
|
Checking formatstring.c...</programlisting>
|
|
|
|
<para>A configuration file can be created that says that the string is a
|
|
format string. For instance:</para>
|
|
|
|
<para><programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<function name="do_something">
|
|
<arg nr="1">
|
|
<formatstr/>
|
|
</arg>
|
|
</function>
|
|
</def></programlisting>Now Cppcheck will report an error:</para>
|
|
|
|
<programlisting>cppcheck --library=test.cfg formatstring.c
|
|
Checking formatstring.c...
|
|
[formatstring.c:3]: (error) do_something format string requires 2 parameters but only 1 is given.</programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Function Argument: Value range</title>
|
|
|
|
<para>The valid values can be defined. Imagine:</para>
|
|
|
|
<programlisting>void test()
|
|
{
|
|
do_something(1024);
|
|
}</programlisting>
|
|
|
|
<para>No error is reported for that:</para>
|
|
|
|
<programlisting># cppcheck valuerange.c
|
|
Checking valuerange.c...</programlisting>
|
|
|
|
<para>A configuration file can be created that says that 1024 is out of
|
|
bounds. For instance:</para>
|
|
|
|
<para><programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<function name="do_something">
|
|
<arg nr="1">
|
|
<valid>0-1023</valid>
|
|
</arg>
|
|
</function>
|
|
</def></programlisting>Now Cppcheck will report an error:</para>
|
|
|
|
<programlisting>cppcheck --library=test.cfg range.c
|
|
Checking range.c...
|
|
[range.c:3]: (error) Invalid do_something() argument nr 1. The value is 1024 but the valid values are '0-1023'.</programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>noreturn</title>
|
|
|
|
<para>Cppcheck doesn't assume that functions always return. Here is an
|
|
example code:</para>
|
|
|
|
<programlisting>void test(int x)
|
|
{
|
|
int data, buffer[1024];
|
|
if (x == 1)
|
|
data = 123;
|
|
else
|
|
ZeroMemory(buffer, sizeof(buffer));
|
|
buffer[0] = data; // <- error: data is uninitialized if x is not 1
|
|
}</programlisting>
|
|
|
|
<para>In theory, if <literal>ZeroMemory</literal> terminates the program
|
|
then there is no bug. Cppcheck therefore reports no error:</para>
|
|
|
|
<programlisting># cppcheck noreturn.c
|
|
Checking noreturn.c...</programlisting>
|
|
|
|
<para>However if you use <literal>--check-library</literal> and
|
|
<literal>--enable=information</literal> you'll get this:</para>
|
|
|
|
<programlisting># cppcheck --check-library --enable=information noreturn.c
|
|
Checking noreturn.c...
|
|
[noreturn.c:7]: (information) --check-library: Function ZeroMemory() should have <noreturn> configuration
|
|
</programlisting>
|
|
|
|
<para>If a proper <literal>windows.cfg</literal> is provided, the bug is
|
|
detected:</para>
|
|
|
|
<programlisting># cppcheck --library=windows.cfg noreturn.c
|
|
Checking noreturn.c...
|
|
[noreturn.c:8]: (error) Uninitialized variable: data</programlisting>
|
|
|
|
<para>Here is a minimal <literal>windows.cfg</literal> file:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<function name="ZeroMemory">
|
|
<noreturn>false</noreturn>
|
|
</function>
|
|
</def></programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>use-retval</title>
|
|
|
|
<para>As long as nothing else is specified, cppcheck assumes that ignoring the return value of a function is ok:</para>
|
|
|
|
<programlisting>bool test(const char* a, const char* b)
|
|
{
|
|
strcmp(a, b); // <- bug: The call of strcmp does not have side-effects, but the return value is ignored.
|
|
return true;
|
|
}</programlisting>
|
|
|
|
<para>In case <literal>strcmp</literal> has side effects, such as assigning the result to one of the parameters passed to it, nothing bad would happen:</para>
|
|
|
|
<programlisting># cppcheck useretval.c
|
|
Checking useretval.c...</programlisting>
|
|
|
|
<para>If a proper <literal>lib.cfg</literal> is provided, the bug is
|
|
detected:</para>
|
|
|
|
<programlisting># cppcheck --library=lib.cfg --enable=warning useretval.c
|
|
Checking useretval.c...
|
|
[noreturn.c:3]: (warning) Return value of function strcmp() is not used.</programlisting>
|
|
|
|
<para>Here is a minimal <literal>lib.cfg</literal> file:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<function name="strcmp">
|
|
<use-retval/>
|
|
</function>
|
|
</def></programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>define</title>
|
|
|
|
<para>Libraries can be used to define preprocessor macros as well. For example:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<define name="NULL_VALUE" value="0"/>
|
|
</def></programlisting>
|
|
|
|
<para>Each occurence of "NULL_VALUE" in the code would then be replaced by "0" at preprocessor stage.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>podtype</title>
|
|
|
|
<para>Lots of code relies on typedefs providing platform independant types. "podtype"-tags can be used to provide necessary information to cppcheck to support them. Without further information, cppcheck does not understand the type "uint16_t" in the following example:</para>
|
|
|
|
<programlisting>void test() {
|
|
uint16_t a;
|
|
}</programlisting>
|
|
|
|
<para>No message about variable 'a' being unused is printed:</para>
|
|
|
|
<programlisting># cppcheck --enable=style unusedvar.cpp
|
|
Checking unusedvar.cpp...</programlisting>
|
|
|
|
<para>If uint16_t is defined in a library as follows, the result improves:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<def>
|
|
<podtype name="uint16_t" sign="u" size="2"/>
|
|
</def></programlisting>
|
|
|
|
<para>The size of the type is specified in bytes. Possible values for the "sign" attribute are "s" (signed) and "u" (unsigned). Both attributes are optional. Using this library, cppcheck prints:</para>
|
|
|
|
<programlisting># cppcheck --library=lib.cfg --enable=style unusedvar.cpp
|
|
Checking unusedvar.cpp...
|
|
[unusedvar.cpp:2]: (style) Unused variable: a</programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Example configuration for strcpy()</title>
|
|
|
|
<para>The proper configuration for the standard strcpy() function would
|
|
be:</para>
|
|
|
|
<programlisting> <function name="strcpy">
|
|
<leak-ignore/>
|
|
<noreturn>false</noreturn>
|
|
<arg nr="1">
|
|
<not-null/>
|
|
</arg>
|
|
<arg nr="2">
|
|
<not-null/>
|
|
<not-uninit/>
|
|
</arg>
|
|
</function></programlisting>
|
|
|
|
<para>The <literal><leak-ignore/></literal> tells Cppcheck to
|
|
ignore this function call in the leaks checking. Passing allocated
|
|
memory to this function won't mean it will be deallocated.</para>
|
|
|
|
<para>The <literal><noreturn></literal> tells Cppcheck if this
|
|
function returns or not.</para>
|
|
|
|
<para>The first argument that the function takes is a pointer. It must
|
|
not be a null pointer, therefore <literal><not-null></literal> is
|
|
used.</para>
|
|
|
|
<para>The second argument the function takes is a pointer. It must not
|
|
be null. And it must point at initialized data. Using
|
|
<literal><not-null></literal> and
|
|
<literal><not-uninit></literal> is correct.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Specifications for all arguments</title>
|
|
|
|
<para>Specifying <literal>-1</literal> as the argument number is going
|
|
to apply a check to all arguments of that function. The specifications
|
|
for individual arguments override this setting.</para>
|
|
</section>
|
|
</chapter>
|
|
|
|
<chapter>
|
|
<title>Rules</title>
|
|
|
|
<para>You can define custom rules using regular expressions.</para>
|
|
|
|
<para>These rules can not perform sophisticated analysis of the code. But
|
|
they give you an easy way to check for various simple patterns in the
|
|
code.</para>
|
|
|
|
<para>To get started writing rules, see the related articles here:</para>
|
|
|
|
<para><uri>http://sourceforge.net/projects/cppcheck/files/Articles/</uri></para>
|
|
|
|
<para>The file format for rules is:</para>
|
|
|
|
<programlisting><?xml version="1.0"?>
|
|
<rule>
|
|
<tokenlist>LIST</tokenlist>
|
|
<pattern>PATTERN</pattern>
|
|
<message>
|
|
<id>ID</id>
|
|
<severity>SEVERITY</severity>
|
|
<summary>SUMMARY</summary>
|
|
</message>
|
|
</rule></programlisting>
|
|
|
|
<para>CDATA can be used to include characters in a pattern that might interfere with XML:</para>
|
|
|
|
<programlisting><![CDATA[some<strange>pattern]]></programlisting>
|
|
|
|
<section>
|
|
<title><tokenlist></title>
|
|
|
|
<para>The <literal><tokenlist></literal> element is optional. With
|
|
this element you can control what tokens are checked. The
|
|
<literal>LIST</literal> can be either <literal>define</literal>,
|
|
<literal>raw</literal>, <literal>normal</literal> or
|
|
<literal>simple</literal>.</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>define</term>
|
|
|
|
<listitem>
|
|
<para>used to check #define preprocessor statements.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>raw</term>
|
|
|
|
<listitem>
|
|
<para>used to check the preprocessor output.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>normal</term>
|
|
|
|
<listitem>
|
|
<para>used to check the <literal>normal</literal> token list.
|
|
There are some simplifications.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>simple</term>
|
|
|
|
<listitem>
|
|
<para>used to check the simple token list. All simplifications are
|
|
used. Most Cppcheck checks use the simple token list.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
<para>If there is no <tokenlist> element then
|
|
<literal>simple</literal> is used automatically.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title><pattern></title>
|
|
|
|
<para>The <literal>PATTERN</literal> is the
|
|
<literal>PCRE</literal>-compatible regular expression that will be
|
|
executed.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title><id></title>
|
|
|
|
<para>The ID specify the user-defined message id.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title><severity></title>
|
|
|
|
<para>The <literal>SEVERITY</literal> must be one of the
|
|
<literal>Cppcheck</literal> severities: <literal>information</literal>,
|
|
<literal>performance</literal>, <literal>portability</literal>,
|
|
<literal>style</literal>, <literal>warning</literal>, or
|
|
<literal>error</literal>.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title><summary></title>
|
|
|
|
<para>Optional. The summary for the message. If no summary is given, the
|
|
matching tokens is written.</para>
|
|
</section>
|
|
</chapter>
|
|
|
|
<chapter>
|
|
<title>Cppcheck extensions with Python</title>
|
|
|
|
<para>Using dump files it is possible to write Cppcheck extensions with
|
|
for instance Python.</para>
|
|
|
|
<para>The <literal>cppcheckdata.py</literal> module
|
|
(<uri>http://github.com/danmar/cppcheck/blob/master/tools/cppcheckdata.py</uri>)
|
|
allows you to load such dump file. It contains
|
|
<literal>Token</literal>/<literal>Variable</literal>/<literal>ValueFlow.Value</literal>/<literal>Scope</literal>
|
|
classes that are similar to the <literal>C++</literal> classes in
|
|
<literal>Cppcheck</literal>-core. The doxygen information for the
|
|
<literal>C++</literal> classes should be somewhat useful for Python
|
|
developers also.</para>
|
|
|
|
<section>
|
|
<title>Simple checker: Division by zero</title>
|
|
|
|
<para>Here is a simple checker:</para>
|
|
|
|
<programlisting>import cppcheckdata
|
|
|
|
data = cppcheckdata.parsedump('1.c.dump')
|
|
|
|
for token in data.tokenlist:
|
|
if token.str == '/' or token.str == '%':
|
|
# Get denominator (2nd operand)
|
|
den = token.astOperand2
|
|
|
|
# Can denominator be zero?
|
|
if den.getValue(0):
|
|
print '[' + token.file + ':' + str(token.linenr) + '] Division by zero'</programlisting>
|
|
|
|
<para>Example usage:</para>
|
|
|
|
<para><programlisting>cppcheck --dump 1.c
|
|
python divzero.py</programlisting></para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Licensing</title>
|
|
|
|
<para>The dump file is just a xml file, so it is an open interface
|
|
without restrictions. You can use it in any way you need.</para>
|
|
|
|
<para>The <literal>cppcheckdata.py</literal> is also free to use. No
|
|
matter if your project is open source or closed source. Use it for any
|
|
purpose.</para>
|
|
</section>
|
|
</chapter>
|
|
|
|
<chapter>
|
|
<title>HTML report</title>
|
|
|
|
<para>You can convert the XML output from cppcheck into a HTML report.
|
|
You'll need Python and the pygments module (<ulink
|
|
url="http://pygments.org/">http://pygments.org/</ulink>) for this to work.
|
|
In the Cppcheck source tree there is a folder <filename
|
|
class="directory">htmlreport</filename> that contains a script that
|
|
transforms a Cppcheck XML file into HTML output.</para>
|
|
|
|
<para>This command generates the help screen:</para>
|
|
|
|
<programlisting>htmlreport/cppcheck-htmlreport -h</programlisting>
|
|
|
|
<para>The output screen says:</para>
|
|
|
|
<programlisting>Usage: cppcheck-htmlreport [options]
|
|
|
|
Options:
|
|
-h, --help show this help message and exit
|
|
--file=FILE The cppcheck xml output file to read defects from.
|
|
Default is reading from stdin.
|
|
--report-dir=REPORT_DIR
|
|
The directory where the html report content is written.
|
|
--source-dir=SOURCE_DIR
|
|
Base directory where source code files can be found.</programlisting>
|
|
|
|
<para>An example usage:</para>
|
|
|
|
<programlisting>./cppcheck gui/test.cpp --xml 2> err.xml
|
|
htmlreport/cppcheck-htmlreport --file=err.xml --report-dir=test1 --source-dir=.</programlisting>
|
|
</chapter>
|
|
|
|
<chapter>
|
|
<title>Graphical user interface</title>
|
|
|
|
<section>
|
|
<title>Introduction</title>
|
|
|
|
<para>A Cppcheck GUI is available.</para>
|
|
|
|
<para>The main screen is shown immediately when the GUI is
|
|
started.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Check source code</title>
|
|
|
|
<para>Use the <guimenu>Check</guimenu> menu.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Inspecting results</title>
|
|
|
|
<para>The results are shown in a list.</para>
|
|
|
|
<para>You can show/hide certain types of messages through the
|
|
<guimenu>View</guimenu> menu.</para>
|
|
|
|
<para>Results can be saved to an XML file that can later be opened. See
|
|
<literal>Save results to file</literal> and <literal>Open
|
|
XML</literal>.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Settings</title>
|
|
|
|
<para>The language can be changed at any time by using the
|
|
<guimenu>Language</guimenu> menu.</para>
|
|
|
|
<para>More settings are available in <menuchoice>
|
|
<guimenu>Edit</guimenu>
|
|
|
|
<guimenuitem>Preferences</guimenuitem>
|
|
</menuchoice>.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Project files</title>
|
|
|
|
<para>The project files are used to store project specific settings.
|
|
These settings are:</para>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>include folders</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>preprocessor defines</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>As you can read in <link
|
|
linkend="preprocessor-configurations">chapter 3</link> in this manual
|
|
the default is that Cppcheck checks all configurations. So only provide
|
|
preprocessor defines if you want to limit the checking.</para>
|
|
</section>
|
|
</chapter>
|
|
</book>
|