The main change here is to use a lazily-populated vector to associate
runtime data with classes instead of referencing them directly from
the class which requires updating immutable references in the heap
image. The other changes employ other strategies to avoid trying to
update immutable references.
The first bug affected POSIX systems: if the app never called
Process.waitFor, we'd never call waitpid on the child and thus leak a
zombie process. This patch ensures that we always call waitpid by
spawning a thread to handle it.
The second bug affected Windows systems: we weren't closing the
child's ends of the stdin, stdout, and stderr pipes after process
creation, which lead to us blocking forever while reading from the
child's stdout or stderr.
Due to a silly cut-and-paste error, we were incorrectly passing the
stdout and stderr file descriptors back from native code to Java,
which prevented reading the output of the child process.
Rather than try to support mixing Avian's core classes with those of
an external class library -- which necessitates adding a lot of stub
methods which throw UnsupportedOperationExceptions, among other
comprimises -- we're looking to support such external class libraries
in their unmodified forms. The latter strategy has already proven
successful with OpenJDK's class library. Thus, this commit removes
the stub methods, etc., which not only cleans up the code but avoids
misleading application developers as to what classes and methods
Avian's built-in class library supports.
The main changes in this commit ensure that we don't hold the global
class lock when doing class resolution using application-defined
classloaders. Such classloaders may do their own locking (in fact,
it's almost certain), making deadlock likely when mixed with VM-level
locking in various orders.
Other changes include a fix to avoid overflow when waiting for
extremely long intervals and a GC root stack mapping bug.
The biggest change in this commit is to split the system classloader
into two: one for boot classes (e.g. java.lang.*) and another for
application classes. This is necessary to make OpenJDK's security
checks happy.
The rest of the changes include bugfixes and additional JVM method
implementations in classpath-openjdk.cpp.
Whereas the GNU Classpath port used the strategy of patching Classpath
with core classes from Avian so as to minimize changes to the VM, this
port uses the opposite strategy: abstract and isolate
classpath-specific features in the VM similar to how we abstract away
platform-specific features in system.h. This allows us to use an
unmodified copy of OpenJDK's class library, including its core classes
and augmented by a few VM-specific classes in the "avian" package.
We were incorrectly returning an empty array when the input was empty,
whereas we ought to return an array containing a single empty string.
When the pattern to match was empty, we went into a loop to create an
infinite list of empty strings, only to crash once we've run out of
memory. This commit addresses both problems.
In order to facilitate making the VM compatible with multiple class
libraries, it's useful to separate the VM-specific representation of
these classes from the library implementations. This commit
introduces VMClass, VMField, and VMMethod for that purpose.
Note the following excerpt from PNGFileFormat.java in SWT:
/*
* InflaterInputStream does not consume all bytes in the stream
* when it is closed. This may leave unread IDAT chunks. The fix
* is to read all available bytes before closing it.
*/
while (stream.available() > 0) stream.read();
stream.close();
This code relies on the documented behavior of
InflaterInputStream.available, which must return "0 after EOF has been
reached, otherwise always return 1". This is unlike
InputStream.available, which is documented to return "the number of
bytes that can be read (or skipped over) from this input stream
without blocking by the next caller of a method for this input
stream", and says nothing about how many bytes are left until the end
of stream.
This commit modifies InflaterInputStream.available to behave according
to Sun's documentation.
In PersistentSet.remove, we were modifying the child node in place
instead of making a copy to update, which would corrupt older
revisions. This commit ensures that we always create a copy if
necessary.
gethostbyname may return any combination of IPv4 and IPv6 addresses,
and it's not safe to assume the first address is IPv4, which is all
our code is currently prepared to handle. In contrast, getaddrinfo
allows us to specify whether we want IPv4, IPv6, or both.
We should eventually make this switch on Windows as well, but the
status of getaddrinfo in Windows 2000 is not clear, and MinGW's
ws2tcpip.h only declares it for XP and above.
This commit also adds InetAddress.getByName for explicit DNS lookups.
