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CDT/Archive/designs/StaticAnalysis
Contents
Goal
To create a light-weight static analysis framework in CDT that allows to easily plug in "checkers" which would perform real analysis on the code to find common defects, violation of policies, etc.
Intended users of the "Codan" framework:
- Tool Vendors
- To create plugins containing end-user checkers and templates
- Software Architects, Process Enforcement
- To create customized new checkers, based on templates (no programming involved)
- To create problems profiles
- Developer, Tester, Code Inspector
- To check for errors as you type and have a quick way to fix them, during development
- To find bugs, security violations, API violations, coding standard violations during code inspection and before code run
Idea is to create a common components and API that are shared between static analysis tools for C/C++, such as:
- User Interface to control the Problems enablement and parameters
- Different launch modes (as you type, on demand, as a builder)
- An eclipse View to display additional problem information (such as extra backtrace or more complex problem parameters)
- A Generic Marker type for problems with extra fields
- API to run log the problems
- Base classes for checkers
- Sample checkers
- JUnit testing framework
Glossary
- Problem
- any reportable item, such as error, warning, violation of any sort, and even search result
- Checker
- program that finds problems
- False Positive
- problem reported by checker which user considers as incorrect report (false)
- False Negative
- problem missed by checker which is a real problem of this type
User Experience
Code Analysis can be invoked in the one of the following ways:
- Select a "Run Code Analysis" command from Navigator context menu (file, directory, project or combination)
- Enable "Run on Build" in Project preferences "C/C++ Code Analysis->Build", in this case it would be run with Incremental and Full Build
User can control Severity and Enablement of Problems on Workspace level or on Project level.
If Problems are found they would be displayed in the Problems view and has specific type, which can be grouped by or filtered out by the view controls.
Examples of possible Problems
- Assignment in condition
if (a=b) { ... }
- Statement has not effect
a+b;
- Function name does not meet policy rules (should start with lowercase letter)
void My_function() {}
- Unused #include
#include <stdio.h> int main() { return 1; }
- Malloc called without sizeof consideration
int * arr = (int *)malloc(20); // should be malloc(20*sizeof(int))
Create a Checker
To create simple checker you would have to extend one of the framework classes, and add extension point where you specify a class name and describe a problem, such as name, default severity, etc. Name would be visible on the Configuration page.
To create a checker:
- ) Define a problem(s) that you checker is capable of finding, cross check existing checkers to see if it is already there, create a bug report describing your intention to implement it
- ) Start coding:
- check out all plugins from dev.eclipse.org:/cvsroot/tools/org.eclipse.cdt/codan (use cdt checkout instructions) as separate eclipse projects
- create a plugin for your checkers or use org.eclipse.cdt.codan.checkers
- create an extension point for org.eclipse.cdt.codan.core.checkers. Specify one or more problem your checker would create with name, id, default severity and enablement
- note: severity of the problem is user defined. If you creating a frontend for command line static analysis tool (such as lint) which can have different severity for same error, you have to create an id per severity per problem type. For example for "Null pointer dereference" you create npd.error and npd.warning ids. User may define both of them as warnings for IDE.
- create a class in selected plugin which implements IChecker interface. You can pick default abstract implementation such as AbstractIndexAstChecker, see examples in org.eclipse.cdt.codan.checkers.sample
- create a tests for your checker, it is pretty easy to do with existing framework see StatementHasNoEffectCheckerTest class as example
- ) Create a patch and attach to your bug
Extension Point
This is example of extension point:
<extension point="org.eclipse.cdt.codan.core.checkers"> <checker class="org.eclipse.cdt.codan.checkers.sample.AssignmentInConditionChecker" id="org.eclipse.cdt.codan.checkers.checker1" name="Assignment in condition"> <problem defaultSeverity="Warning" id="org.eclipse.cdt.codan.checkers.sample.assignment_in_condition" name="Assignment in condition"> </problem> </checker> </extension>
API
API would contain:
- Interfaces such as IProblem, IProblemCategory, IChecker, etc
- Interface to call Problem Logging - provides means to report a problem (which would become a marker)
- Interface to query status of problem enablement (for optimization purposes)
- Abstract classes for Checkers (such as AbstractIndexAstChecker). For example class for C AST Visitor, which would use CDT C/C++ AST to find errors. Checker can also use other models and even just plain text files (to find swear words or something...)
- Programmatic access to a launch the analysis
- Problem profile change listener - this allows for example to save problems enablement to a file to use in external make integrations
Non API Framework Parts:
- Builder - framework would register a project builder for "Code Analysis". This builder can be used by all checkers and can be turn on/off by user, which allow to perform checks while building (or not)
- Run On demand - provides a command to run "Code Analysis" on demand on selected file or set of resources
- Problem configuration - provide workspace level and project level problem configuration that allows to turn problems on and off, and change severity between standard problem severity
- Marker Type - provide a market type for simple problems. Sophisticated checker can use their own marker types.
- Common Categories - set of common Categories for problems, such as Java has, for example "Programming Errors", "Unused Code and Objects", "Security Violations"...
- Checkers extension point - allows to contribute a checker by using extension point, which means different problems can be contributed by different plugins with potentially different vendors, but would have same user interface and look and feel.
Current code resides in dev.eclipse.org:/cvsroot/tools/org.eclipse.cdt/codan
Deployment
Current this framework is not packaged with CDT. To include it in your CDT based tool you need to manually export plugins located in dev.eclipse.org:/cvsroot/tools/org.eclipse.cdt/codan (can be done using export wizard) and add them to your distribution.
Future work
- User defined checker's preferences, for example if it checkers for policy violations on function name let user specify name pattern using UI
- Build shared models other than AST with bindings, such as Control Graph, Data Flow Graph (this was done in ptp project, maybe just bring it over)
- Some common code to support Quick Fix for the problems
- Common scope filters for checkers (excluded/included files)
Source & Bugs
Source located at
dev.eclipse.org:/cvsroot/tools/org.eclipse.cdt/codan
Send questions to cdt-dev list:
https://dev.eclipse.org/mailman/listinfo/cdt-dev
Send bugs to
- Project: Tools->CDT
- Component: cdt-source-nav
- Prefix: [code analysis]