walkero
/
cppcheck
1
0
Fork 0
Code Issues Pull Requests Projects Releases 1 Wiki Activity

Writing rules: Target this guide for beginners. Skip C++ and only describe how rules are created with regular expressions.

This commit is contained in:
Daniel Marjamäki 2010-12-04 20:01:55 +01:00
parent 04b811b74f
commit 80b2c0594b
1 changed files with 55 additions and 125 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

138
man/writing-rules.docbook
View File

@ -21,8 +21,8 @@
<section>
<title>Introduction</title>
<para>This is supposed to be a manual for developers who want to write
Cppcheck rules.</para>
<para>This is a short guide for developers who want to write Cppcheck
rules.</para>
<para>There are two ways to write rules.</para>
@ -46,130 +46,73 @@
</varlistentry>
</variablelist>
<para>The data used by the rules are not the raw source code. Cppcheck
will read the source code and process it before the rules are used.</para>
<para>It is a good first step to use regular expressions. It is easier.
You'll get results quicker. Therefore this guide will focus on regular
expressions.</para>
</section>
<section>
<title>Data representation of the source code</title>
<para>There are two types of data you can use: symbol database and token
list.</para>
<para>The data used by the rules are not the raw source code.
<literal>Cppcheck</literal> will read the source code and process it
before the rules are used.</para>
<section>
<title>Token lists</title>
<para>Cppcheck is designed to find bugs and dangerous code. Stylistic
information such as indentation, comments, etc are filtered out at an
early state. You don't need to worry about such stylistic information when
you write rules.</para>
<para>The code is stored in token lists (simple double-linked
lists).</para>
<para>Between each token in the code there is always a space. For instance
the raw code "1+f()" is processed into "1 + f ( )".</para>
<para>The token lists are designed for rule matching. All redundant
information is removed. A number of transformations are made
automatically on the token lists to simplify writing rules.</para>
<para>The class <literal>Tokenizer</literal> create the token lists and
perform all simplifications.</para>
<para>The class <literal>Token</literal> is used for every token in the
token list. The <literal>Token</literal> class also contain
functionality for matching tokens.</para>
<section>
<title>Normal token list</title>
<para>The first token list that is created has many basic
simplifications. For example:</para>
<para>The code is simplified in many ways. For example:</para>
<itemizedlist>
<listitem>
<para>There are no templates. Templates have been
instantiated.</para>
<para>The templates are instantiated</para>
</listitem>
<listitem>
<para>There is no "else if". These are converted into "else { if
.."</para>
<para>The typedefs are handled</para>
</listitem>
<listitem>
<para>The bodies of "if", "else", "while", "do" and "for" are
always enclosed in "{" and "}".</para>
<para>There is no "else if". These are converted into "else {
if.."</para>
</listitem>
<listitem>
<para>A declaration of multiple variables is split up into
multiple variable declarations. "int a,b;" =&gt; "int a; int
b;"</para>
<para>The bodies of "if", "else", "while", "do" and "for" are always
enclosed in "{" and "}"</para>
</listitem>
<listitem>
<para>All variables have unique ID numbers</para>
<para>A declaration of multiple variables is split up into multiple
variable declarations. "int a,b;" =&gt; "int a; int b;"</para>
</listitem>
</itemizedlist>
</section>
<section>
<title>Simplified token list</title>
<para>The second token list that is created has all simplifications
the normal token list has and then many more simplifications. For
example:</para>
<itemizedlist>
<listitem>
<para>There is no sizeof</para>
</listitem>
<listitem>
<para>There are no templates.</para>
<para>NULL is replaced with 0</para>
</listitem>
<listitem>
<para>Control flow transformations.</para>
<para>Static value flow analysis is made. Known values are inserted
into the code.</para>
</listitem>
<listitem>
<para>NULL is replaced with 0.</para>
</listitem>
<listitem>
<para>Static value flow analysis is made. Known values are
inserted into the code.</para>
</listitem>
<listitem>
<para>variable initialization is replaced with assignment</para>
<para>.. and many more</para>
</listitem>
</itemizedlist>
<para>The simple token list is written if you use
<literal>--debug</literal>. For example, use <literal>cppcheck --debug
test1.cpp</literal> and check this code:</para>
<programlisting>void f1() {
int a = 1;
f2(a++);
}</programlisting>
<para>The result is:</para>
<programlisting>##file test1.cpp
1: void f1 ( ) {
2: ; ;
3: f2 ( 1 ) ;
4: }</programlisting>
<para></para>
</section>
<section>
<title>Reference</title>
<para>To learn more about the token lists, the doxygen information for
the <literal>Tokenizer</literal> is recommended.</para>
<para>http://cppcheck.sourceforge.net/doxyoutput/classTokenizer.html</para>
</section>
</section>
<para>The simplifications are made in the <literal>Cppcheck</literal>
<literal>Tokenizer</literal>. For more information see:
<uri>http://cppcheck.sourceforge.net/doxyoutput/classTokenizer.html</uri></para>
</section>
<section>
@ -189,10 +132,10 @@
</listitem>
</itemizedlist>
<para>Here is an example:</para>
<para>Here is a simple example:</para>
<programlisting>&lt;?xml version="1.0"?&gt;
&lt;rule data="simple"&gt;
&lt;rule version="1"&gt;
&lt;pattern&gt;/ 0&lt;/pattern&gt;
&lt;message&gt;
&lt;id&gt;divbyzero&lt;/id&gt;
@ -201,21 +144,8 @@
&lt;/message&gt;
&lt;/rule&gt;</programlisting>
<para>It is recommended that you use the <literal>simple</literal> token
list whenever you can. If you need some information that is removed in it
then try the <literal>normal</literal> token list.</para>
<para></para>
<para>When you write the patterns remember that;</para>
<itemizedlist>
<listitem>
<para>tokens are always separated by spaces. "1+2" is not
possible.</para>
</listitem>
<listitem>
<para>there is no indentation, spaces, comments, line breaks.</para>
</listitem>
</itemizedlist>
<para></para>
</section>
</article>