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/*
* Copyright (C) 2011 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 java.nio;
import android.system.ErrnoException;
import java.io.FileDescriptor;
import java.io.IOException;
import libcore.io.Libcore;
/**
* Used to implement java.nio read(ByteBuffer[])/write(ByteBuffer[]) operations as POSIX readv(2)
* and writev(2) calls.
*/
final class IoVec {
enum Direction { READV, WRITEV };
private final ByteBuffer[] byteBuffers;
private final int offset;
private final int bufferCount;
private final Object[] ioBuffers;
private final int[] offsets;
private final int[] byteCounts;
private final Direction direction;
IoVec(ByteBuffer[] byteBuffers, int offset, int bufferCount, Direction direction) {
this.byteBuffers = byteBuffers;
this.offset = offset;
this.bufferCount = bufferCount;
this.direction = direction;
this.ioBuffers = new Object[bufferCount];
this.offsets = new int[bufferCount];
this.byteCounts = new int[bufferCount];
}
int init() {
int totalRemaining = 0;
for (int i = 0; i < bufferCount; ++i) {
ByteBuffer b = byteBuffers[i + offset];
if (direction == Direction.READV) {
b.checkWritable();
}
int remaining = b.remaining();
if (b.isDirect()) {
ioBuffers[i] = b;
offsets[i] = b.position();
} else {
ioBuffers[i] = NioUtils.unsafeArray(b);
offsets[i] = NioUtils.unsafeArrayOffset(b) + b.position();
}
byteCounts[i] = remaining;
totalRemaining += remaining;
}
return totalRemaining;
}
int doTransfer(FileDescriptor fd) throws IOException {
try {
if (direction == Direction.READV) {
int result = Libcore.os.readv(fd, ioBuffers, offsets, byteCounts);
if (result == 0) {
result = -1;
}
return result;
} else {
return Libcore.os.writev(fd, ioBuffers, offsets, byteCounts);
}
} catch (ErrnoException errnoException) {
throw errnoException.rethrowAsIOException();
}
}
void didTransfer(int byteCount) {
for (int i = 0; byteCount > 0 && i < bufferCount; ++i) {
ByteBuffer b = byteBuffers[i + offset];
if (byteCounts[i] < byteCount) {
b.position(b.limit());
byteCount -= byteCounts[i];
} else {
b.position((direction == Direction.WRITEV ? b.position() : 0) + byteCount);
byteCount = 0;
}
}
}
}
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