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/*
* Copyright (C) 2012 The CyanogenMod 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 com.cyanogenmod.filemanager.util;
import android.app.ActivityManager;
import android.app.ActivityManager.MemoryInfo;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.Signature;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.os.UserHandle;
import android.os.UserManager;
import android.util.DisplayMetrics;
import android.view.ViewConfiguration;
import com.android.internal.util.HexDump;
import java.io.ByteArrayInputStream;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
/**
* A helper class with useful methods for deal with android.
*/
public final class AndroidHelper {
private static Boolean sIsAppPlatformSigned;
/**
* Method that returns if the device is a tablet
*
* @param ctx The current context
* @return boolean If device is a table
*/
public static boolean isTablet(Context ctx) {
Configuration configuration = ctx.getResources().getConfiguration();
return (configuration.screenLayout & Configuration.SCREENLAYOUT_SIZE_MASK)
>= Configuration.SCREENLAYOUT_SIZE_LARGE;
}
/**
* Method that returns if an option menu has to be displayed
*
* @param ctx The current context
* @return boolean If an option menu has to be displayed
*/
public static boolean showOptionsMenu(Context ctx) {
// Show overflow button?
return !ViewConfiguration.get(ctx).hasPermanentMenuKey();
}
/**
* This method converts dp unit to equivalent device specific value in pixels.
*
* @param ctx The current context
* @param dp A value in dp (Device independent pixels) unit
* @return float A float value to represent Pixels equivalent to dp according to device
*/
public static float convertDpToPixel(Context ctx, float dp) {
Resources resources = ctx.getResources();
DisplayMetrics metrics = resources.getDisplayMetrics();
return dp * (metrics.densityDpi / 160f);
}
/**
* This method converts device specific pixels to device independent pixels.
*
* @param ctx The current context
* @param px A value in px (pixels) unit
* @return A float value to represent dp equivalent to px value
*/
public static float convertPixelsToDp(Context ctx, float px) {
Resources resources = ctx.getResources();
DisplayMetrics metrics = resources.getDisplayMetrics();
return px / (metrics.densityDpi / 160f);
}
/**
* Method that check if the app is signed with the platform signature
*
* @param ctx The current context
* @return boolean If the app is signed with the platform signature
*/
public static boolean isAppPlatformSignature(Context ctx) {
if (sIsAppPlatformSigned == null) {
try {
// First check that the app is installed as a system app
PackageManager pm = ctx.getPackageManager();
ApplicationInfo ai = pm.getApplicationInfo(ctx.getPackageName(),
PackageManager.GET_SIGNATURES);
if ((ai.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {
sIsAppPlatformSigned = Boolean.FALSE;
} else {
final MessageDigest sha1 = MessageDigest.getInstance("SHA1");
final CertificateFactory cf = CertificateFactory.getInstance("X.509");
// Get signature of the current package
PackageInfo info = pm.getPackageInfo(ctx.getPackageName(),
PackageManager.GET_SIGNATURES);
Signature[] signatures = info.signatures;
X509Certificate cert = (X509Certificate) cf.generateCertificate(
new ByteArrayInputStream(signatures[0].toByteArray()));
sha1.update(cert.getEncoded());
String appHash = HexDump.toHexString(sha1.digest());
// Get the signature of the system package
info = pm.getPackageInfo("android",
PackageManager.GET_SIGNATURES);
signatures = info.signatures;
cert = (X509Certificate) cf.generateCertificate(
new ByteArrayInputStream(signatures[0].toByteArray()));
sha1.update(cert.getEncoded());
String systemHash = HexDump.toHexString(sha1.digest());
// Is platform signed?
sIsAppPlatformSigned = appHash.equals(systemHash);
}
} catch (NameNotFoundException e) {
sIsAppPlatformSigned = Boolean.FALSE;
} catch (GeneralSecurityException e) {
sIsAppPlatformSigned = Boolean.FALSE;
}
}
return sIsAppPlatformSigned.booleanValue();
}
public static boolean hasSupportForMultipleUsers(Context context) {
return UserManager.supportsMultipleUsers();
}
public static boolean isUserOwner() {
return UserHandle.myUserId() == UserHandle.USER_OWNER;
}
public static boolean isSecondaryUser(Context context) {
return AndroidHelper.hasSupportForMultipleUsers(context)
&& !AndroidHelper.isUserOwner();
}
public static long getAvailableMemory(Context context) {
ActivityManager am = (ActivityManager) context.getSystemService(
Context.ACTIVITY_SERVICE);
MemoryInfo memoryInfo = new MemoryInfo();
am.getMemoryInfo(memoryInfo);
return memoryInfo.availMem;
}
}
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