/*
 * Copyright (C) 2010 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.permission.cts;

import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.test.AndroidTestCase;
import android.test.suitebuilder.annotation.MediumTest;

import java.io.File;
import java.io.FileFilter;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Verify certain permissions on the filesystem
 *
 * TODO: Combine this file with {@link android.os.cts.FileAccessPermissionTest}
 */
@MediumTest
public class FileSystemPermissionTest extends AndroidTestCase {

    public void testCreateFileHasSanePermissions() throws Exception {
        File myFile = new File(getContext().getFilesDir(), "hello");
        FileOutputStream stream = new FileOutputStream(myFile);
        stream.write("hello world".getBytes());
        stream.close();
        try {
            FileUtils.FileStatus status = new FileUtils.FileStatus();
            FileUtils.getFileStatus(myFile.getAbsolutePath(), status, false);
            int expectedPerms = FileUtils.S_IFREG
                    | FileUtils.S_IWUSR
                    | FileUtils.S_IRUSR;
            assertEquals(
                    "Newly created files should have 0600 permissions",
                    Integer.toOctalString(expectedPerms),
                    Integer.toOctalString(status.mode));
        } finally {
            assertTrue(myFile.delete());
        }
    }

    public void testCreateDirectoryHasSanePermissions() throws Exception {
        File myDir = new File(getContext().getFilesDir(), "helloDirectory");
        assertTrue(myDir.mkdir());
        try {
            FileUtils.FileStatus status = new FileUtils.FileStatus();
            FileUtils.getFileStatus(myDir.getAbsolutePath(), status, false);
            int expectedPerms = FileUtils.S_IFDIR
                    | FileUtils.S_IWUSR
                    | FileUtils.S_IRUSR
                    | FileUtils.S_IXUSR;
            assertEquals(
                    "Newly created directories should have 0700 permissions",
                    Integer.toOctalString(expectedPerms),
                    Integer.toOctalString(status.mode));

        } finally {
            assertTrue(myDir.delete());
        }
    }

    public void testOtherApplicationDirectoriesAreNotWritable() throws Exception {
        List<ApplicationInfo> apps = getContext()
                .getPackageManager()
                .getInstalledApplications(PackageManager.GET_UNINSTALLED_PACKAGES);
        String myAppDirectory = getContext().getApplicationInfo().dataDir;
        for (ApplicationInfo app : apps) {
            if (!myAppDirectory.equals(app.dataDir)) {
                assertDirectoryAndSubdirectoriesNotWritable(new File(app.dataDir));
            }
        }
    }

    public void testApplicationParentDirectoryNotWritable() throws Exception {
        String myDataDir = getContext().getApplicationInfo().dataDir;
        File parentDir = new File(myDataDir).getParentFile();
        assertDirectoryNotWritable(parentDir);
    }

    public void testDataDirectoryNotWritable() throws Exception {
        assertDirectoryNotWritable(Environment.getDataDirectory());
    }

    public void testAndroidRootDirectoryNotWritable() throws Exception {
        assertDirectoryNotWritable(Environment.getRootDirectory());
    }

    public void testDownloadCacheDirectoryNotWritable() throws Exception {
        assertDirectoryNotWritable(Environment.getDownloadCacheDirectory());
    }

    public void testRootDirectoryNotWritable() throws Exception {
        assertDirectoryNotWritable(new File("/"));
    }

    public void testDevDirectoryNotWritable() throws Exception {
        assertDirectoryNotWritable(new File("/dev"));
    }

    public void testProcDirectoryNotWritable() throws Exception {
        assertDirectoryNotWritable(new File("/proc"));
    }

    public void testDevMemSane() throws Exception {
        File f = new File("/dev/mem");
        assertFalse(f.canRead());
        assertFalse(f.canWrite());
        assertFalse(f.canExecute());
    }

    public void testDevkmemSane() throws Exception {
        File f = new File("/dev/kmem");
        assertFalse(f.canRead());
        assertFalse(f.canWrite());
        assertFalse(f.canExecute());
    }

    public void testDevPortSane() throws Exception {
        File f = new File("/dev/port");
        assertFalse(f.canRead());
        assertFalse(f.canWrite());
        assertFalse(f.canExecute());
    }

    private static void assertDirectoryNotWritable(File directory) throws Exception {
        File toCreate = new File(directory, "hello");
        try {
            toCreate.createNewFile();
            fail("Expected \"java.io.IOException: Permission denied\""
                 + " when trying to create " + toCreate.getAbsolutePath());
        } catch (IOException e) {
            // It's expected we'll get a "Permission denied" exception.
        } finally {
            toCreate.delete();
        }
    }

    /**
     * Verify that any publicly readable directories reachable from
     * the root directory are not writable.
     *
     * Note: Because not all directories are readable, this is a best-effort
     * test only.  Writable directories within unreadable subdirectories
     * will NOT be detected by this code.
     */
    public void testAllOtherDirectoriesNotWritable() throws Exception {
        File start = new File("/");
        assertDirectoryAndSubdirectoriesNotWritable(start);
    }

    private static final Set<String> OTHER_RANDOM_DIRECTORIES = new HashSet<String>(
            Arrays.asList(
                    "/data/backup",
                    "/data/secure",
                    "/data/system",
                    "/data/dalvik-cache",
                    "/data/property",
                    "/data/app",
                    "/data/app-private",
                    "/data/local",
                    "/data/misc",
                    "/data/dontpanic",
                    "/data/lost+found",
                    "/data/drm",
                    "/data/drm/rights",
                    "/data/data/.drm",
                    "/data/data/.drm/.wmdrm"
            )
    );

    /**
     * Because /data and /data/data are not readable, we blindly try to
     * poke around in there looking for bad directories.  There has to be
     * a better way...
     */
    public void testOtherRandomDirectoriesNotWritable() throws Exception {
        for (String dir : OTHER_RANDOM_DIRECTORIES) {
            File start = new File(dir);
            assertDirectoryAndSubdirectoriesNotWritable(start);
        }
    }

    public void testAllBlockDevicesAreNotReadableWritable() throws Exception {
        assertBlockDevicesInDirAndSubDirAreNotWritable(new File("/dev"));
    }

    private static void
    assertBlockDevicesInDirAndSubDirAreNotWritable(File dir) throws Exception {
        assertTrue(dir.isDirectory());
        File[] subDirectories = dir.listFiles(new FileFilter() {
            @Override public boolean accept(File pathname) {
                return pathname.isDirectory();
            }
        });


        /* recurse into subdirectories */
        if (subDirectories != null) {
            for (File f : subDirectories) {
                assertBlockDevicesInDirAndSubDirAreNotWritable(f);
            }
        }

        File[] filesInThisDirectory = dir.listFiles();
        if (filesInThisDirectory == null) {
            return;
        }

        for (File f: filesInThisDirectory) {
            FileUtils.FileStatus status = new FileUtils.FileStatus();
            FileUtils.getFileStatus(f.getAbsolutePath(), status, false);
            if (status.hasModeFlag(FileUtils.S_IFBLK)) {
                assertFalse(f.getCanonicalPath(), f.canRead());
                assertFalse(f.getCanonicalPath(), f.canWrite());
                assertFalse(f.getCanonicalPath(), f.canExecute());
            }
        }
    }

    private void assertDirectoryAndSubdirectoriesNotWritable(File dir) throws Exception {
        if (!dir.isDirectory()) {
            return;
        }

        if (!dir.getAbsolutePath().equals(dir.getCanonicalPath())) {
            // don't follow symbolic links.
            return;
        }

        String myHome = getContext().getApplicationInfo().dataDir;
        String thisDir = dir.getCanonicalPath();
        if (thisDir.startsWith(myHome)) {
            // Don't examine directories within our home directory.
            // We expect these directories to be writable.
            return;
        }

        assertDirectoryNotWritable(dir);

        File[] subFiles = dir.listFiles();
        if (subFiles == null) {
            return;
        }

        for (File f : subFiles) {
            assertDirectoryAndSubdirectoriesNotWritable(f);
        }
    }
}