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/*
* Copyright (C) 2015 Dominik Schürmann <dominik@dominikschuermann.de>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.sufficientlysecure.keychain.util;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import android.annotation.TargetApi;
import android.content.ContentResolver;
import android.content.res.AssetFileDescriptor;
import android.net.Uri;
import android.os.Build.VERSION_CODES;
import android.os.ParcelFileDescriptor;
import android.system.ErrnoException;
import android.system.Os;
import android.system.StructStat;
import org.sufficientlysecure.keychain.Constants;
/**
* FileHelper methods which use Lollipop-exclusive API.
* Some of the methods and static fields used here cause VerifyErrors because
* they do not exist in pre-lollipop API, so they must be kept in a
* lollipop-only class. All methods here should only be called by FileHelper,
* and consequently have package visibility.
*/
@TargetApi(VERSION_CODES.LOLLIPOP)
class FileHelperLollipop {
/**
* A replacement for ContentResolver.openInputStream() that does not allow the usage of
* "file" Uris that point to private files owned by the application only.
*
* This is not allowed:
* am start -a android.intent.action.SEND -t text/plain -n
* "org.sufficientlysecure.keychain.debug/org.sufficientlysecure.keychain.ui.EncryptFilesActivity" --eu
* android.intent.extra.STREAM
* file:///data/data/org.sufficientlysecure.keychain.debug/databases/openkeychain.db
*
* @throws FileNotFoundException
*/
static InputStream openInputStreamSafe(ContentResolver resolver, Uri uri)
throws FileNotFoundException {
String scheme = uri.getScheme();
if (ContentResolver.SCHEME_FILE.equals(scheme)) {
ParcelFileDescriptor pfd = ParcelFileDescriptor.open(
new File(uri.getPath()), ParcelFileDescriptor.parseMode("r"));
try {
final StructStat st = Os.fstat(pfd.getFileDescriptor());
if (st.st_uid == android.os.Process.myUid()) {
Log.e(Constants.TAG, "File is owned by the application itself, aborting!");
throw new FileNotFoundException("Unable to create stream");
}
} catch (ErrnoException e) {
Log.e(Constants.TAG, "fstat() failed: " + e);
throw new FileNotFoundException("fstat() failed");
}
AssetFileDescriptor fd = new AssetFileDescriptor(pfd, 0, -1);
try {
return fd.createInputStream();
} catch (IOException e) {
throw new FileNotFoundException("Unable to create stream");
}
} else {
return resolver.openInputStream(uri);
}
}
}
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