Hi Paul,
On 04/14/2016 04:40 PM, Paul Sandoz wrote:
Hi Peter,
You found that annoying restriction :-) at this point i think this is mostly
redundant.
This is something i planned to update and limit the restriction to code within
j.l.invoke and sun.invoke packages.
sun.invoke is explicitly allowed currently.
I'll follow up with a patch soon to unblock, but feel free to beat me to it if
you wish.
I don't quite understand this restriction. Seems to be that it was
written at the time where the only classes loaded by bootstrap class
loader were located in packages java.** and sun.** (was that actually
true at some point?) and the restriction explicitly excludes classes in
sun.invoke.** packages as though they are the only trusted code to be
able to obtain such lookup. Does a Lookup with a lookup class loaded by
the bootstrap class loader and allowedModes == ALL_MODES possess any
special privileges that a Lookup with a lookup class loaded by the
application class loader and allowedModes == ALL_MODES doesn't?
Regards, Peter
Paul.
On 14 Apr 2016, at 16:25, Peter Levart <peter.lev...@gmail.com> wrote:
Hi Paul,
I wanted to try using VarHandles for code internal to JDK but there's a problem
with MethodHandles.lookup(). It doesn't allow the caller class loaded by the
bootstrap class loader and located in either java.* or sun.* (but not
sun.invoke.*) packages:
private static void checkUnprivilegedlookupClass(Class<?> lookupClass,
int allowedModes) {
String name = lookupClass.getName();
if (name.startsWith("java.lang.invoke."))
throw newIllegalArgumentException("illegal lookupClass:
"+lookupClass);
// For caller-sensitive MethodHandles.lookup()
// disallow lookup more restricted packages
if (allowedModes == ALL_MODES && lookupClass.getClassLoader() ==
null) {
if (name.startsWith("java.") ||
(name.startsWith("sun.") &&
!name.startsWith("sun.invoke."))) {
throw newIllegalArgumentException("illegal lookupClass: " +
lookupClass);
}
}
}
...strangely, other bootstrap class loaded callers located in jdk.* are allowed. Why such
distinction? Is there or will there be an official way to use VarHandles in JDK code and
not having to resort to work-arounds like
MethodHandles.Lookup.class.getDeclaredField("IMPL_LOOKUP").setAccessible(true)?
Regards, Peter
