On 5/2/2012 11:09 AM, Artem Ananiev wrote:
Hi, Mandy,
the client part of the fix looks fine.
Thanks for the review. I have pushed the changeset and hope you don't
mind I couldn't fix the changeset comment to add you as a reviewer.
Let me ask a naive question, though.
From your explanation, I see that System.loadLibrary() is now aware of
modules. What prevents us to change LoadLibraryAction the same way?
"FROM" code looks much more elegant than the new (the old?) "TO" one.
I would say the old code is little compact than the new one and both
versions look elegant to me.
The fix here is to get the caller of System.loadLibrary be in the same
class loader as the native library being loaded (see
ClassLoader.findLibrary).
Another alternative is that each component can have its own copy of
LoadLibraryAction (e.g. sun.awt.LoadLibraryAction) and so you can modify
the old code like this:
java.security.AccessController.doPrivileged(new
sun.awt.LoadLibraryAction("awt"));
provided that sun.awt.LoadLibraryAction is loaded by the same class
loader with whom awt.dll is associated. Adding one copy of this simple
LoadLibraryAction utility class for each component seems overkill and
also error-prone e.g. refactoring a module into two modules require
adding another copy of this per-module utility class if both have native
libraries. This is certainly an option if the component team prefers to
use the utility class.
Mandy
Thanks,
Artem
On 4/26/2012 10:49 PM, Mandy Chung wrote:
7164376 Replace use of sun.security.action.LoadLibraryAction
with direct call of System.loadLibrary
Webrev:
http://cr.openjdk.java.net/~mchung/jdk8/webrevs/7164376/webrev.00/
This change is required for jdk modularization. High level summary:
it replaces the use of LoadLibraryAction:
FROM:
java.security.AccessController.doPrivileged(new
LoadLibraryAction("net"));
TO:
AccessController.doPrivileged(
new java.security.PrivilegedAction<Void>() {
public Void run() {
System.loadLibrary("net");
return null;
}
});
It touches files in awt, security and serviceability area (cc'ed).
For this type of simple change, I think 1-2 reviewers can
review all files (simpler to review jdk.patch) and no need
for all teams to do the reviews.
System.loadLibrary and Runtime.loadLibrary loads a system library of the
given
library name that requires RuntimePermission("loadLibrary."+lib)
permission.
Many places in the JDK code loading a system native library is using the
sun.security.action.LoadLibraryAction convenient class that will load
the
system library as a privileged action:
java.security.AccessController.doPrivileged(new
LoadLibraryAction("net"));
The search path of native libraries are coupled with an associated class
loader.
For example, the application class loader uses the path specified in the
"java.library.path" system property for native library lookup. The
loadLibrary
implementation uses the caller's class loader for finding the native
library being
requested. For system libraries, the class loader is null and the system
library
lookup is handled as a special case. When the
sun.security.action.LoadLibraryAction
class is used that is the caller of System.loadLibrary, the caller's
class loader
in this case is "null" loader and thus it always finds the native
library from
the system library path.
In a modular world, JDK modules may be loaded by multiple different
module class
loader. The following code would not work if it is expected to load a
native
library from a module which is not the module where the
sun.security.action.LoadLibraryAction lives.
For example, the management module is trying to load libmanagement.so.
Calling
the following will fail to find libmanagement.so because the caller of
System.loadLibrary is the LoadLibraryAction which is in the base module
and search the library from the base module only. To prepare for jdk
modularization, the use of LoadLibraryAction should be replaced with
a direct call of System.loadLibrary.
This patch also removes sun.security.action.LoadLibraryAction
class to avoid regression.
Thanks
Mandy
