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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.os;
import static android.system.OsConstants.F_DUPFD_CLOEXEC;
import android.annotation.NonNull;
import android.annotation.SystemApi;
import android.annotation.TestApi;
import android.system.ErrnoException;
import android.system.Os;
import java.io.Closeable;
import java.io.FileDescriptor;
/**
* Collection representing a set of open file descriptors and an opaque data stream.
*
* @hide
*/
@SystemApi
@TestApi
public final class NativeHandle implements Closeable {
// whether this object owns mFds
private boolean mOwn = false;
private FileDescriptor[] mFds;
private int[] mInts;
/**
* Constructs a {@link NativeHandle} object containing
* zero file descriptors and an empty data stream.
*/
public NativeHandle() {
this(new FileDescriptor[0], new int[0], false);
}
/**
* Constructs a {@link NativeHandle} object containing the given
* {@link FileDescriptor} object and an empty data stream.
*/
public NativeHandle(@NonNull FileDescriptor descriptor, boolean own) {
this(new FileDescriptor[] {descriptor}, new int[0], own);
}
/**
* Convenience method for creating a list of file descriptors.
*
* @hide
*/
private static FileDescriptor[] createFileDescriptorArray(@NonNull int[] fds) {
FileDescriptor[] list = new FileDescriptor[fds.length];
for (int i = 0; i < fds.length; i++) {
FileDescriptor descriptor = new FileDescriptor();
descriptor.setInt$(fds[i]);
list[i] = descriptor;
}
return list;
}
/**
* Convenience method for instantiating a {@link NativeHandle} from JNI. It does
* not take ownership of the int[] params. It does not dupe the FileDescriptors.
*
* @hide
*/
private NativeHandle(@NonNull int[] fds, @NonNull int[] ints, boolean own) {
this(createFileDescriptorArray(fds), ints, own);
}
/**
* Instantiate an opaque {@link NativeHandle} from fds and integers.
*
* @param own whether the fds are owned by this object and should be closed
*/
public NativeHandle(@NonNull FileDescriptor[] fds, @NonNull int[] ints, boolean own) {
mFds = fds.clone();
mInts = ints.clone();
mOwn = own;
}
/**
* Returns whether this {@link NativeHandle} object contains a single file
* descriptor and nothing else.
*
* @return a boolean value
*/
public boolean hasSingleFileDescriptor() {
checkOpen();
return mFds.length == 1 && mInts.length == 0;
}
/**
* Explicitly duplicate NativeHandle (this dups all file descritptors).
*
* If this method is called, this must also be explicitly closed with
* {@link #close()}.
*/
public @NonNull NativeHandle dup() throws java.io.IOException {
FileDescriptor[] fds = new FileDescriptor[mFds.length];
try {
for (int i = 0; i < mFds.length; i++) {
FileDescriptor newFd = new FileDescriptor();
int fdint = Os.fcntlInt(mFds[i], F_DUPFD_CLOEXEC, 0);
newFd.setInt$(fdint);
fds[i] = newFd;
}
} catch (ErrnoException e) {
e.rethrowAsIOException();
}
return new NativeHandle(fds, mInts, true /*own*/);
}
private void checkOpen() {
if (mFds == null) {
throw new IllegalStateException("NativeHandle is invalidated after close.");
}
}
/**
* Closes the file descriptors if they are owned by this object.
*
* This also invalidates the object.
*/
@Override
public void close() throws java.io.IOException {
checkOpen();
if (mOwn) {
try {
for (FileDescriptor fd : mFds) {
Os.close(fd);
}
} catch (ErrnoException e) {
e.rethrowAsIOException();
}
mOwn = false;
}
mFds = null;
mInts = null;
}
/**
* Returns the underlying lone file descriptor.
*
* @return a {@link FileDescriptor} object
* @throws IllegalStateException if this object contains either zero or
* more than one file descriptor, or a non-empty data stream.
*/
public @NonNull FileDescriptor getFileDescriptor() {
checkOpen();
if (!hasSingleFileDescriptor()) {
throw new IllegalStateException(
"NativeHandle is not single file descriptor. Contents must"
+ " be retreived through getFileDescriptors and getInts.");
}
return mFds[0];
}
/**
* Convenience method for fetching this object's file descriptors from JNI.
* @return a mutable copy of the underlying file descriptors (as an int[])
*
* @hide
*/
private int[] getFdsAsIntArray() {
checkOpen();
int numFds = mFds.length;
int[] fds = new int[numFds];
for (int i = 0; i < numFds; i++) {
fds[i] = mFds[i].getInt$();
}
return fds;
}
/**
* Fetch file descriptors
*
* @return the fds.
*/
public @NonNull FileDescriptor[] getFileDescriptors() {
checkOpen();
return mFds;
}
/**
* Fetch opaque ints. Note: This object retains ownership of the data.
*
* @return the opaque data stream.
*/
public @NonNull int[] getInts() {
checkOpen();
return mInts;
}
}
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