Static Analysis of PHP Code – IPC Berlin 2016

Static Analysis of PHP
Code
How the Heck did I write so many Bugs?
International PHP Conference Berlin, June 2016
By Rouven Weßling ( )
Ecosystem Developer / Developer Evangelist, Contentful
@RouvenWessling
photo credit: by Achim FischerBrandenburg Gate Berlin (license)

Analysing software without
executing it.

Dynamic Analysis
xdebug
xhprof
PHP Analyzer
PHP Vulnerability Hunter
Assertions

Spend less time on unit tests...

class ClientTest extends PHPUnit_Framework_TestCase
{
public function testGetSynchronizationManager()
{
$client = new Client('b4c0n73n7fu1', 'cfexampleapi');
$this->assertInstanceOf(Manager::class, $client->getSynchronizationManager());
}
}

Easy to integrate in Continuous
Integration

Find issues that can not be found
through unit tests

PHP 7
Abstract Syntax Tree
Scalar Types
Strict Types

PHP is dynamic
Reﬂection
Variable variables
Referencing classes/functions/properties by string

The more static your code is, the
easier it's to reason about.

phpmd phan phpcs phpunit phploc phpcpd phpsa php7cc
Coupling Detector Mondrian PHP
Assumption PhpCodeAnalyzer PHPCodeFixer php7mar PHP
Semantic Versioning Checker PHP Inspection PHP
lint PHP Depend PhpMetrics PHPCheckstyle PHP
Reaper PHP vuln hunter RIPS Parse SonarQube Side
Channel
Analyzer TaintPHP Deptrac PhpDependencyAnalysis PHP
semver checker

phpmd phan phpcs phpunit phploc phpcpd phpsa php7cc
Reaper PHP vuln hunter Parse SonarQube Side
Channel
semver checker

phpmd phan phpcs phpunit phploc phpcpd phpsa PHP
Reaper PHP vuln hunter Parse SonarQube Side
Channel
semver checker

Compiles PHP script with the actual PHP compiler
It's already installed on your computer
Can be used to test compatibility with multiple PHP
versions

<?php
namespace ContentfulLog
use PsrHttpMessageRequestInterface;
use PsrHttpMessageResponseInterface;
class NullLogger implements LoggerInterface
{
public function getTimer()
{
return new NullTimer;
}
public function log($api, RequestInterface $request, StandardTimer $timer, ResponseInter
{
}
}

PHP 7.0.3 | 10 parallel jobs
.................................X...... 40/40 (100 %)
Checked 40 files in 0.5 seconds
Syntax error found in 1 file
------------------------------------------------------------
Parse error: src/Log/NullLogger.php:9
7| namespace ContentfulLog
8|
> 9| use PsrHttpMessageRequestInterface;
10| use PsrHttpMessageResponseInterface;
11|
Unexpected 'use' (T_USE), expecting '{'

Make your life easier
Use PHP-Parallel-Lint

Software has layers
There should be rules about those layers
Rules are easily broken

1. Define the layers of your architecture
2. Define what layers another layer can access
3. Profit!!!

layers:
- name: Controller
collectors:
- type: className
regex: .*Controller.*
- name: Entity
collectors:
- type: className
regex: AstaRwthVorkursticketBundleEntity.*

ruleset:
Controller:
- Service
- Entity
- Form
Service:
- Repository
Command:
- Entity
Entity:
- Validator

How it works
Parses all ﬁles in your code
Stores which classes access which others classes
Checks the graph for rule violations

deptrac is alpha, not production ready.
please help us and report feedback / bugs.
Start to create an AstMap for 24 Files.
........................
AstMap created.
start emitting dependencies "InheritanceDependencyEmitter"
start emitting dependencies "BasicDependencyEmitter"
end emitting dependencies
start flatten dependencies
end flatten dependencies
collecting violations.
formatting dependencies.
[...]ServicesPdfOrder::5 must not depend on [...]EntityVorkursticket (Service on Entity)
[...]ServicesPdfOrder::23 must not depend on [...]EntityVorkursticket (Service on Entity)
Found 2 Violations

Type safety for PHP
Checks docblocks
Signature mismatches
Unused code

How it works
Makes 2 passes over the codebase
1. Build a list of all classes, functions, methods, etc.
2. Go trough each function and follow the type of
each variable

/**
* @param Locale|string|null $locale
*
* @return string
*/
public function getDescription($locale = null)
{
$localeCode = $this->getLocaleFromInput($locale);
// This checks happens after the call to getLocaleFromInput to make sure
// the Exception for invalid locales is still thrown.
if ($this->description === null) {
return null;
}
return $this->description->$localeCode;
}
src/Delivery/Asset.php:74 PhanTypeMismatchReturn Returning type null
but getDescription() is declared to return string

class ContentType
{
/**
* The fields, keyed by ID.
*
* @var object
*/
private $fields = [];
}
src/Delivery/ContentType.php:34 PhanTypeMismatchProperty Assigning array to
property but contentfuldeliverycontenttype::fields is object

public function __call($name, $arguments)
{
// Lots of code here
if ($result instanceof Link) {
return $client->resolveLink($result);
}
return array_map(function ($value) use ($client) {
if ($value instanceof Link) {
return $client->resolveLink($value);
}
return $value;
}, $result);
}
src/Delivery/DynamicEntry.php:126
PhanTypeMismatchArgumentInternal Argument 2 (input1) is
contentfuldeliverylink but array_map() takes array
Not a bug

Bad news?
Requires php-ast
Not easy to deal with library code
Noisy - not easily integrated in CI.

phan is using brute force for type checking
Roughly as good as the compiler for a statically
typed language
Works, but a Control Flow Graph could give even
deeper insight

int foo(int length) {
int x = 0;
for (int i = 0; i < length; i++)
x += 1
return length/x;
}

Bottom line
There are dozens of tools - pick what's necessary for
you
Make them part of your Continuous Integration setup
Never trust. Make sure you understand where the
error is coming from.

Slides available on Slideshare:
http://www.slideshare.net/rwessling/static-analysis-of-
php-code-ipc-berlin-2016

Static Analysis of PHP Code – IPC Berlin 2016

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