On 01/07/2019 20:51, Mandy Chung wrote:
This is an enhancement to |`Lookup::in`| and
|`MethodHandles::privateLookupIn`| API
for cross module teleporting. A `Lookup` object will record the previous
lookup class from which this |Lookup| object was teleported such that
the access check will use both the previous lookup class and the current
|lookup| context (current lookup class and allowed modes) to determine if
a type is accessible to this `Lookup` object or not.
In a nutshell, `T` in M2 is accessible to a `Lookup` object on `C`
(lookup class in M1) and `PLC` (previous lookup class in M0) if and
only if
1. both M0 and M1 can read M2
2. T is in a package that is exported from M2 at least to both M0 and M1
Detailed specification is in Lookup class spec and `accessClass` javadoc.
The relevant spec about cross-module teleporting is in the Lookup class
spec and `Lookup::in` and `MethodHandles::privateLookupIn`.
CSR: https://bugs.openjdk.java.net/browse/JDK-8226916
webrev:
http://cr.openjdk.java.net/~mchung/jdk14/8173978/webrev.00
javadoc:
http://cr.openjdk.java.net/~mchung/jdk14/8173978/javadoc/java.base/java/lang/invoke/MethodHandles.Lookup.html
http://cr.openjdk.java.net/~mchung/jdk14/8173978/javadoc/java.base/java/lang/invoke/MethodHandles.html#privateLookupIn(java.lang.Class,java.lang.invoke.MethodHandles.Lookup)
This is really good work and fixes several issues left over from JDK 9.
The compatibility issues (mostly small/advanced) are unfortunate but
necessary and I hope it won't impact too many things. It will need a
detail release note once the CSR is done and the changes are in.
I've taken several passes over the changes and I don't see anything
obviously wrong. One minor nit is that the @throws
IllegalAccessException in accessClass(Class) needs to be updated to
allow for it to thrown when not accessible from the previous lookup
class. Also VerifyAccess::isModuleAccessible shouldn't need to if the
package is exported unconditionally as it is covered by isExported(pn,
m1) && isExported(pn, m2).
-Alan
