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Writing rules: Added one more example for the C++ intro

This commit is contained in:
Daniel Marjamäki 2011-01-08 10:20:29 +01:00
parent d758929490
commit c39fab721d
1 changed files with 103 additions and 4 deletions
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107
man/writing-rules-3.docbook
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@ -73,7 +73,10 @@ void CheckOther::divisionByZero()
// Report error
void CheckOther::divisionByZeroError()
{
reportError(tok, Severity::error, "divisionByZero", "Division by zero");
reportError(tok, // location
Severity::error, // severity
"divisionByZero", // id
"Division by zero"); // message
}</programlisting>
<para>The <literal>Token::Match</literal> matches tokens against
@ -111,7 +114,8 @@ void CheckOther::divisionByZeroError()
<programlisting>if ( %var% ) { free ( %var% ) ; }</programlisting>
<para>Any variable name is matched by <literal>%var%</literal>.</para>
<para>The <literal>%var%</literal> pattern is used to match any variable
name.</para>
<para>Here is a C++ function:</para>
@ -143,10 +147,105 @@ void CheckOther::dealloc()
// Report warning
void CheckOther::deallocWarning()
{
reportError(tok, Severity::warning, "dealloc", "Redundant condition before deallocation");
reportError(tok, // location
Severity::warning, // severity
"dealloc", // id
"Redundant condition"); // message
}</programlisting>
<para>The strAt function is used to fetch strings from the token list. The
parameter specifies the token offset.</para>
parameter specifies the token offset. The result for "tok-&gt;tokAt(1)" is
the same as for "tok-&gt;next()".</para>
</section>
<section>
<title>Validate function parameters</title>
<para>Sometimes it is known that a function can't handle certain
parameters. Here is an example rule that checks that the parameters for
strtol or strtoul are valid:</para>
<programlisting>//---------------------------------------------------------------------------
// strtol(str, 0, radix) &lt;- radix must be 0 or 2-36
//---------------------------------------------------------------------------
void CheckOther::invalidFunctionUsage()
{
// Loop through all tokens
for (const Token *tok = _tokenizer-&gt;tokens(); tok; tok = tok-&gt;next())
{
// Is there a function call for strtol or strtoul?
if (!Token::Match(tok, "strtol|strtoul ("))
continue;
// Locate the third parameter of the function call..
// Counter that counts the parameters.
int param = 1;
// Scan the function call tokens. The "tok-&gt;tokAt(2)" returns
// the token after the "("
for (const Token *tok2 = tok-&gt;tokAt(2); tok2; tok2 = tok2-&gt;next())
{
// If a "(" is found then jump to the corresponding ")"
if (tok2-&gt;str() == "(")
tok2 = tok2-&gt;link();
// End of function call.
else if (tok2-&gt;str() == ")")
break;
// Found a ",". increment param counter
else if (tok2-&gt;str() == ",")
{
++param;
// If the param is 3 then check if the parameter is valid
if (param == 3)
{
if (Token::Match(tok2, ", %num% )"))
{
// convert next token into a number
MathLib::bigint radix;
radix = MathLib::toLongNumber(tok2-&gt;strAt(1));
// invalid radix?
if (!(radix == 0 || (radix &gt;= 2 &amp;&amp; radix &lt;= 36)))
{
dangerousUsageStrtolError(tok2);
}
}
break;
}
}
}
}
}
void CheckOther::dangerousUsageStrtolError(const Token *tok)
{
reportError(tok, // location
Severity::error, // severity
"dangerousUsageStrtol", // id
"Invalid radix"); // message
}</programlisting>
<para>The link() member function is used to find the corresponding ( ) [ ]
or { } token.</para>
<para>The inner loop is not necessary if you just want to get the last
parameter. This code will check if the last parameter is
numerical..</para>
<programlisting>..
// Is there a function call?
if (!Token::Match(tok, "do_something ("))
continue;
if (Token::Match(tok-&gt;next()-&gt;link()-&gt;tokAt(-2), "(|, %num% )"))
...</programlisting>
<para>The pattern <literal>(|,</literal> can also be written as
<literal>[(,]</literal>.</para>
</section>
</article>