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https://github.com/spirals-team/casper
Open-science code of "Casper: Automatic Tracking of Null Dereferences to Inception with Causality Traces" (JSS'16).
https://github.com/spirals-team/casper
debug open-science
Last synced: 5 days ago
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Open-science code of "Casper: Automatic Tracking of Null Dereferences to Inception with Causality Traces" (JSS'16).
- Host: GitHub
- URL: https://github.com/spirals-team/casper
- Owner: Spirals-Team
- Created: 2015-09-09T15:18:18.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2024-08-05T09:37:36.000Z (5 months ago)
- Last Synced: 2024-08-05T11:19:45.516Z (5 months ago)
- Topics: debug, open-science
- Language: Java
- Homepage: https://hal.archives-ouvertes.fr/hal-01354090/document
- Size: 572 KB
- Stars: 3
- Watchers: 11
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
Casper
=====
A tool for finding the root cause of null pointer exceptions through causality traces
Casper: Automatic Tracking of Null Dereferences to Inception with Causality Traces (Benoit Cornu, Earl T. Barr, Martin Monperrus and Lionel Seinturier), In Journal of Systems and Software, Elsevier, 2016.
```
@article{cornu:hal-01354090,
title = {{Casper: Automatic Tracking of Null Dereferences to Inception with Causality Traces}},
author = {Cornu, Benoit and Barr, Earl T. and Monperrus, Martin and Seinturier, Lionel},
url = {https://hal.archives-ouvertes.fr/hal-01354090/document},
doi = {10.1016/j.jss.2016.08.062},
journal = {{Journal of Systems and Software}},
publisher = {{Elsevier}},
year = {2016},
}
```
Casper: Debugging Null Dereferences with Dynamic Causality Traces (Benoit Cornu, Earl T. Barr, Lionel Seinturier, Martin Monperrus), Technical report hal-01113988, Inria Lille, 2015.
The evaluation dataset is at
To run casper on a simple example:
`mvn test`
it creates `spooned/FooCasper.java` and `spooned/FooCasperNullified.java` (the ghost class).
It triggers a deluxe NPE of the form (printed on the console):
```
throws NPE calling bar at FooCasper.bug1(FooCasper.java:15)
parameter o is null in foo5 at (FooCasper.java:38)
returned null in method foo5 (FooCasper.java:39)
field/array access on null at (FooCasper.java:43)
throws NPE at FooCasper.bug2(FooCasper.java:40)
```
Casper has two modes for creating ghost classes: source transformation and binary transformation at loading time.
To use the former, you have to use a custom classloader as system classloader.
-Djava.system.class.loader=sacha.reflect.classloading.PermissiveClassLoader
Example of modified Java code
-----------------------------
(excerpt from `spooned/FooCasper.java`)
Before:
```java
public FooCasper bug1() {
if (new FooCasper(1).foo() != null) {
throw new Error();
}
FooCasper g = new FooCasper(1).foo();
f=g;
System.out.println(f);
f.bar(); // the NPE
return null;
}
```
After:
```java
public FooCasper bug1() {
if (isNotNull(new FooCasper().foo())) {
throw new java.lang.Error();
}
FooCasper g = setAssigned(new FooCasper().foo(), FooCasper.class, "g (FooCasper.java:14)");
f = setAssigned(g, FooCasper.class, "f (FooCasper.java:15)");
System.out.println(f);
f.bar();
return setReturn(null, FooCasper.class, "bug1 (FooCasper.java:19)");
}
```
Notes:
* Update for support with Java 17: need to expose private APIs at compile time and runtime (`--add-exports java.base/jdk.internal.vm.annotation=ALL-UNNAMED`)