3.6 KiB
| title | description |
|---|---|
| Pulse | Memory and lifetime analysis. |
Memory and lifetime analysis.
Activate with --pulse.
Supported languages:
- C/C++/ObjC: Yes
- Java: Yes
- C#/.Net: No
What is Infer:Pulse?
Pulse is an interprocedural memory safety analysis. Pulse can detect, for instance, Null dereferences in Java. Errors are only reported when all conditions on the erroneous path are true regardless of input. Pulse should gradually replace the original biabduction analysis of Infer. An example of a Null dereference found by Pulse is given below.
class Person {
Person emergencyContact;
String address;
Person getEmergencyContact() {
return this.emergencyContact;
}
}
class Registry {
void create() {
Person p = new Person();
Person c = p.getEmergencyContact();
// Null dereference here
System.out.println(c.address);
}
void printContact(Person p) {
// No null dereference, as we don't know anything about `p`
System.out.println(p.getEmergencyContact().address);
}
}
How to run pulse for Java:
infer run --pulse -- javac Test.java
Pulse reports a Null dereference on this file on create(), as it tries to access the field address of object c, and c has value null. In contrast, Pulse gives no report for printContact(Person p), as we cannot be sure that p.getEmergencyContact() will return null. Pulse then labels this error as latent and only reports if there is a call to printContact(Person p) satisfying the condition for Null dereference.
Pulse x Nullsafe
Nullsafe is a type checker for @Nullable annotations for Java. Classes following the Nullsafe discipline are annotated with @Nullsafe.
Consider the classes Person and Registry from the previous example. Assuming that class Person is annotated with @Nullsafe. In this case, we also annotate getEmergencyContact() with @Nullable, to make explicit that this method can return the null value. There is still the risk that classes depending on Person have Null dereferences. In this case, Pulse would report a Null dereference on Registry. It could also be the case that class Registry is annotated with @Nullsafe. By default Pulse reports on @Nullsafe files too, see the --pulse-nullsafe-report-npe option (Facebook-specific: Pulse does not report on @Nullsafe files).
@Nullsafe(Nullsafe.Mode.LOCAL)
class Person {
Person emergencyContact;
String address;
@Nullable Person getEmergencyContact() {
return this.emergencyContact;
}
}
class Registry {
... // Pulse reports here
}
List of Issue Types
The following issue types are reported by this checker: