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@fython
Last active February 16, 2022 14:48
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StorageManagaerCompat (openProxyFileDescriptor pre-O)
/**
* No Licenses. Use it in your favourite way.
*/
import android.content.Context;
import android.os.Build;
import android.os.Handler;
import android.os.ParcelFileDescriptor;
import android.os.ProxyFileDescriptorCallback;
import android.os.storage.StorageManager;
import android.support.annotation.NonNull;
import android.support.annotation.RequiresApi;
import android.system.ErrnoException;
import android.system.OsConstants;
import android.util.Log;
import java.io.IOException;
/**
* @author Fung Gwo (fythonx@gmail.com)
*/
public final class StorageManagerCompat {
private final static String TAG = StorageManagerCompat.class.getSimpleName();
@NonNull
public static final StorageManagerCompat from(@NonNull Context context) {
return new StorageManagerCompat(context);
}
private StorageManager mStorageManager;
private StorageManagerCompat(@NonNull Context context) {
mStorageManager = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);
}
@NonNull
public ParcelFileDescriptor openProxyFileDescriptor(int mode, @NonNull ProxyFileDescriptorCallbackCompat callback, @NonNull Handler handler) throws IOException {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
return mStorageManager.openProxyFileDescriptor(
mode,
callback.toAndroidOsProxyFileDescriptorCallback(),
handler
);
} else {
if (ParcelFileDescriptor.MODE_READ_ONLY != mode
&& ParcelFileDescriptor.MODE_WRITE_ONLY != mode) {
throw new UnsupportedOperationException("Mode " + mode + " is not supported");
}
ParcelFileDescriptor[] pipe = ParcelFileDescriptor.createReliablePipe();
switch (mode) {
case ParcelFileDescriptor.MODE_READ_ONLY : {
handler.post(new Runnable() {
@Override
public void run() {
try (final ParcelFileDescriptor.AutoCloseOutputStream os =
new ParcelFileDescriptor.AutoCloseOutputStream(pipe[1])) {
int size = (int) callback.onGetSize();
byte[] buf = new byte[size];
callback.onRead(0, size, buf);
os.write(buf);
callback.onRelease();
} catch (IOException | ErrnoException e) {
Log.e(TAG, "Failed to read file.", e);
try {
pipe[1].closeWithError(e.getMessage());
} catch (IOException exc) {
Log.e(TAG, "Can't even close PFD with error.", exc);
}
}
}
});
return pipe[0];
}
case ParcelFileDescriptor.MODE_WRITE_ONLY : {
handler.post(new Runnable() {
@Override
public void run() {
try (final ParcelFileDescriptor.AutoCloseInputStream is =
new ParcelFileDescriptor.AutoCloseInputStream(pipe[0])) {
byte[] buf = new byte[is.available()];
is.read(buf);
callback.onWrite(0, buf.length, buf);
callback.onRelease();
} catch (IOException | ErrnoException e) {
Log.e(TAG, "Failed to write file.", e);
try {
pipe[0].closeWithError(e.getMessage());
} catch (IOException exc) {
Log.e(TAG, "Can't even close PFD with error.", exc);
}
}
}
});
return pipe[1];
}
default: {
// Should never happen.
pipe[0].close();
pipe[1].close();
throw new UnsupportedOperationException("Mode " + mode + " is not supported.");
}
}
}
}
public static abstract class ProxyFileDescriptorCallbackCompat {
/**
* Returns size of bytes provided by the file descriptor.
* @return Size of bytes.
* @throws ErrnoException ErrnoException containing E constants in OsConstants.
*/
public long onGetSize() throws ErrnoException {
throw new ErrnoException("onGetSize", OsConstants.EBADF);
}
/**
* Provides bytes read from file descriptor.
* It needs to return exact requested size of bytes unless it reaches file end.
* @param offset Offset in bytes from the file head specifying where to read bytes. If a seek
* operation is conducted on the file descriptor, then a read operation is requested, the
* offset refrects the proper position of requested bytes.
* @param size Size for read bytes.
* @param data Byte array to store read bytes.
* @return Size of bytes returned by the function.
* @throws ErrnoException ErrnoException containing E constants in OsConstants.
*/
public int onRead(long offset, int size, byte[] data) throws ErrnoException {
throw new ErrnoException("onRead", OsConstants.EBADF);
}
/**
* Handles bytes written to file descriptor.
* @param offset Offset in bytes from the file head specifying where to write bytes. If a seek
* operation is conducted on the file descriptor, then a write operation is requested, the
* offset refrects the proper position of requested bytes.
* @param size Size for write bytes.
* @param data Byte array to be written to somewhere.
* @return Size of bytes processed by the function.
* @throws ErrnoException ErrnoException containing E constants in OsConstants.
*/
public int onWrite(long offset, int size, byte[] data) throws ErrnoException {
throw new ErrnoException("onWrite", OsConstants.EBADF);
}
/**
* Ensures all the written data are stored in permanent storage device.
* For example, if it has data stored in on memory cache, it needs to flush data to storage
* device.
* @throws ErrnoException ErrnoException containing E constants in OsConstants.
*/
public void onFsync() throws ErrnoException {
throw new ErrnoException("onFsync", OsConstants.EINVAL);
}
/**
* Invoked after the file is closed.
*/
abstract void onRelease();
@RequiresApi(Build.VERSION_CODES.O)
@NonNull
ProxyFileDescriptorCallback toAndroidOsProxyFileDescriptorCallback() {
return new ProxyFileDescriptorCallback() {
@Override
public int onRead(long offset, int size, byte[] data) throws ErrnoException {
return ProxyFileDescriptorCallbackCompat.this.onRead(offset, size, data);
}
@Override
public int onWrite(long offset, int size, byte[] data) throws ErrnoException {
return ProxyFileDescriptorCallbackCompat.this.onWrite(offset, size, data);
}
@Override
public long onGetSize() throws ErrnoException {
return ProxyFileDescriptorCallbackCompat.this.onGetSize();
}
@Override
public void onFsync() throws ErrnoException {
ProxyFileDescriptorCallbackCompat.this.onFsync();
}
@Override
public void onRelease() {
ProxyFileDescriptorCallbackCompat.this.onRelease();
}
};
}
}
}
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