PKMS中卸载应用是通过deletePackage函数来执行，这个函数主要是调用了一些Observer回调，然后调用了deletePackageX函数。
public void deletePackage(final String packageName,
final IPackageDeleteObserver2 observer, final int userId, final int flags) {
mContext.enforceCallingOrSelfPermission(
android.Manifest.permission.DELETE_PACKAGES, null);
Preconditions.checkNotNull(packageName);
Preconditions.checkNotNull(observer);
final int uid = Binder.getCallingUid();
if (UserHandle.getUserId(uid) != userId) {
mContext.enforceCallingPermission(
android.Manifest.permission.INTERACT_ACROSS_USERS_FULL,
"deletePackage for user " + userId);
}
if (isUserRestricted(userId, UserManager.DISALLOW_UNINSTALL_APPS)) {
try {
observer.onPackageDeleted(packageName,//回调
PackageManager.DELETE_FAILED_USER_RESTRICTED, null);
} catch (RemoteException re) {
}
return;
}
boolean uninstallBlocked = false;
if ((flags & PackageManager.DELETE_ALL_USERS) != 0) {
int[] users = sUserManager.getUserIds();
for (int i = 0; i < users.length; ++i) {
if (getBlockUninstallForUser(packageName, users[i])) {
uninstallBlocked = true;
break;
}
}
} else {
uninstallBlocked = getBlockUninstallForUser(packageName, userId);
}
if (uninstallBlocked) {
try {
observer.onPackageDeleted(packageName, PackageManager.DELETE_FAILED_OWNER_BLOCKED,
null);
} catch (RemoteException re) {
}
return;
}
if (DEBUG_REMOVE) {
Slog.d(TAG, "deletePackageAsUser: pkg=" + packageName + " user=" + userId);
}
// Queue up an async operation since the package deletion may take a little while.
mHandler.post(new Runnable() {//异步调用deletePackageX函数
public void run() {
mHandler.removeCallbacks(this);
final int returnCode = deletePackageX(packageName, userId, flags);
if (observer != null) {
try {
observer.onPackageDeleted(packageName, returnCode, null);
} catch (RemoteException e) {
Log.i(TAG, "Observer no longer exists.");
} //end catch
} //end if
} //end run
});
}我们来看下deletePackageX函数，主要是调用deletePackageLI函数继续执行，关键当返回的info不为空就调用info.args.doPostDeleteLI(true)删除应用。
private int deletePackageX(String packageName, int userId, int flags) {
......
synchronized (mInstallLock) {
if (DEBUG_REMOVE) Slog.d(TAG, "deletePackageX: pkg=" + packageName + " user=" + userId);
res = deletePackageLI(packageName, removeForUser,
true, allUsers, perUserInstalled,
flags | REMOVE_CHATTY, info, true);
systemUpdate = info.isRemovedPackageSystemUpdate;
if (res && !systemUpdate && mPackages.get(packageName) == null) {
removedForAllUsers = true;
}
if (DEBUG_REMOVE) Slog.d(TAG, "delete res: systemUpdate=" + systemUpdate
+ " removedForAllUsers=" + removedForAllUsers);
}
......
// Force a gc here.
Runtime.getRuntime().gc();
// Delete the resources here after sending the broadcast to let
// other processes clean up before deleting resources.
if (info.args != null) {
synchronized (mInstallLock) {
info.args.doPostDeleteLI(true);//删除资源、apk等
}
}
return res ? PackageManager.DELETE_SUCCEEDED : PackageManager.DELETE_FAILED_INTERNAL_ERROR;
}我们来看deletePackageLI函数，如果只有data，直接调用removePackageDataLI函数。如果是系统应用调用deleteSystemPackageLI，不是调用deleteInstalledPackageLI函数。
private boolean deletePackageLI(String packageName, UserHandle user,
boolean deleteCodeAndResources, int[] allUserHandles, boolean[] perUserInstalled,
int flags, PackageRemovedInfo outInfo,
boolean writeSettings) {
......
if (dataOnly) {
// Delete application data first
if (DEBUG_REMOVE) Slog.d(TAG, "Removing package data only");
removePackageDataLI(ps, null, null, outInfo, flags, writeSettings);
return true;
}
boolean ret = false;
if (isSystemApp(ps)) {
if (DEBUG_REMOVE) Slog.d(TAG, "Removing system package:" + ps.name);
// When an updated system application is deleted we delete the existing resources as well and
// fall back to existing code in system partition
ret = deleteSystemPackageLI(ps, allUserHandles, perUserInstalled,
flags, outInfo, writeSettings);
} else {
if (DEBUG_REMOVE) Slog.d(TAG, "Removing non-system package:" + ps.name);
// Kill application pre-emptively especially for apps on sd.
killApplication(packageName, ps.appId, "uninstall pkg");
ret = deleteInstalledPackageLI(ps, deleteCodeAndResources, flags,
allUserHandles, perUserInstalled,
outInfo, writeSettings);
}
return ret;
}卸载系统应用
为什么会有卸载系统应用呢，当我们调用scanPackageLI扫描目录时有时候失败，也需要调用deletePackageLI来删除apk，这个时候就会有系统应用了。
private boolean deleteSystemPackageLI(PackageSetting newPs,
int[] allUserHandles, boolean[] perUserInstalled,
int flags, PackageRemovedInfo outInfo, boolean writeSettings) {
final boolean applyUserRestrictions
= (allUserHandles != null) && (perUserInstalled != null);
PackageSetting disabledPs = null;
// Confirm if the system package has been updated
// An updated system app can be deleted. This will also have to restore
// the system pkg from system partition
// reader
synchronized (mPackages) {
disabledPs = mSettings.getDisabledSystemPkgLPr(newPs.name);
}
if (DEBUG_REMOVE) Slog.d(TAG, "deleteSystemPackageLI: newPs=" + newPs
+ " disabledPs=" + disabledPs);
if (disabledPs == null) {
Slog.w(TAG, "Attempt to delete unknown system package "+ newPs.name);
return false;
} else if (DEBUG_REMOVE) {
Slog.d(TAG, "Deleting system pkg from data partition");
}
// Delete the updated package
outInfo.isRemovedPackageSystemUpdate = true;
if (disabledPs.versionCode < newPs.versionCode) {
// Delete data for downgrades
flags &= ~PackageManager.DELETE_KEEP_DATA;//是否保留资源
} else {
// Preserve data by setting flag
flags |= PackageManager.DELETE_KEEP_DATA;
}
boolean ret = deleteInstalledPackageLI(newPs, true, flags,//卸载apk
allUserHandles, perUserInstalled, outInfo, writeSettings);
if (!ret) {
return false;
}
// writer
synchronized (mPackages) {
// Reinstate the old system package
mSettings.enableSystemPackageLPw(newPs.name);
// Remove any native libraries from the upgraded package.
NativeLibraryHelper.removeNativeBinariesLI(newPs.legacyNativeLibraryPathString);
}
// Install the system package
int parseFlags = PackageParser.PARSE_MUST_BE_APK | PackageParser.PARSE_IS_SYSTEM;
if (locationIsPrivileged(disabledPs.codePath)) {
parseFlags |= PackageParser.PARSE_IS_PRIVILEGED;
}
final PackageParser.Package newPkg;
try {
newPkg = scanPackageLI(disabledPs.codePath, parseFlags, SCAN_NO_PATHS, 0, null);//重新apk扫描目录
} catch (PackageManagerException e) {
Slog.w(TAG, "Failed to restore system package:" + newPs.name + ": " + e.getMessage());
return false;
}
// writer
synchronized (mPackages) {
PackageSetting ps = mSettings.mPackages.get(newPkg.packageName);
// Propagate the permissions state as we do not want to drop on the floor
// runtime permissions. The update permissions method below will take
// care of removing obsolete permissions and grant install permissions.
ps.getPermissionsState().copyFrom(newPs.getPermissionsState());
updatePermissionsLPw(newPkg.packageName, newPkg,
UPDATE_PERMISSIONS_ALL | UPDATE_PERMISSIONS_REPLACE_PKG);
if (applyUserRestrictions) {
if (DEBUG_REMOVE) {
Slog.d(TAG, "Propagating install state across reinstall");
}
for (int i = 0; i < allUserHandles.length; i++) {
if (DEBUG_REMOVE) {
Slog.d(TAG, " user " + allUserHandles[i]
+ " => " + perUserInstalled[i]);
}
ps.setInstalled(perUserInstalled[i], allUserHandles[i]);
mSettings.writeRuntimePermissionsForUserLPr(allUserHandles[i], false);
}
// Regardless of writeSettings we need to ensure that this restriction
// state propagation is persisted
mSettings.writeAllUsersPackageRestrictionsLPr();
}
// can downgrade to reader here
if (writeSettings) {
mSettings.writeLPr();//更新packages.xml
}
}
return true;
}卸载系统应用，最后也是调用deleteInstalledPackageLI来完成卸载的，我们来看下这个函数。
卸载普通应用
卸载普通应用就直接调用了deleteInstalledPackageLI函数
private boolean deleteInstalledPackageLI(PackageSetting ps,
boolean deleteCodeAndResources, int flags,
int[] allUserHandles, boolean[] perUserInstalled,
PackageRemovedInfo outInfo, boolean writeSettings) {
if (outInfo != null) {
outInfo.uid = ps.appId;
}
// Delete package data from internal structures and also remove data if flag is set
removePackageDataLI(ps, allUserHandles, perUserInstalled, outInfo, flags, writeSettings);
// Delete application code and resources
if (deleteCodeAndResources && (outInfo != null)) {
outInfo.args = createInstallArgsForExisting(packageFlagsToInstallFlags(ps),
ps.codePathString, ps.resourcePathString, getAppDexInstructionSets(ps));
if (DEBUG_SD_INSTALL) Slog.i(TAG, "args=" + outInfo.args);
}
return true;
}我们先看removePackageDataLI函数，就是删除各种资源，但是我们没看到删除apk文件。
private void removePackageDataLI(PackageSetting ps,
int[] allUserHandles, boolean[] perUserInstalled,
PackageRemovedInfo outInfo, int flags, boolean writeSettings) {
String packageName = ps.name;
if (DEBUG_REMOVE) Slog.d(TAG, "removePackageDataLI: " + ps);
removePackageLI(ps, (flags&REMOVE_CHATTY) != 0);
// Retrieve object to delete permissions for shared user later on
final PackageSetting deletedPs;
// reader
synchronized (mPackages) {
deletedPs = mSettings.mPackages.get(packageName);
if (outInfo != null) {
outInfo.removedPackage = packageName;
outInfo.removedUsers = deletedPs != null
? deletedPs.queryInstalledUsers(sUserManager.getUserIds(), true)
: null;
}
}
if ((flags&PackageManager.DELETE_KEEP_DATA) == 0) {
removeDataDirsLI(ps.volumeUuid, packageName);// 卸载data目录
schedulePackageCleaning(packageName, UserHandle.USER_ALL, true);
}
// writer
synchronized (mPackages) {
if (deletedPs != null) {
if ((flags&PackageManager.DELETE_KEEP_DATA) == 0) {
clearIntentFilterVerificationsLPw(deletedPs.name, UserHandle.USER_ALL);
clearDefaultBrowserIfNeeded(packageName);
if (outInfo != null) {
mSettings.mKeySetManagerService.removeAppKeySetDataLPw(packageName);
outInfo.removedAppId = mSettings.removePackageLPw(packageName);
}
updatePermissionsLPw(deletedPs.name, null, 0);
if (deletedPs.sharedUser != null) {
// Remove permissions associated with package. Since runtime
// permissions are per user we have to kill the removed package
// or packages running under the shared user of the removed
// package if revoking the permissions requested only by the removed
// package is successful and this causes a change in gids.
for (int userId : UserManagerService.getInstance().getUserIds()) {
final int userIdToKill = mSettings.updateSharedUserPermsLPw(deletedPs,
userId);
if (userIdToKill == UserHandle.USER_ALL
|| userIdToKill >= UserHandle.USER_OWNER) {
// If gids changed for this user, kill all affected packages.
mHandler.post(new Runnable() {
@Override
public void run() {
// This has to happen with no lock held.
killApplication(deletedPs.name, deletedPs.appId,
KILL_APP_REASON_GIDS_CHANGED);
}
});
break;
}
}
}
clearPackagePreferredActivitiesLPw(deletedPs.name, UserHandle.USER_ALL);
}
// make sure to preserve per-user disabled state if this removal was just
// a downgrade of a system app to the factory package
if (allUserHandles != null && perUserInstalled != null) {
if (DEBUG_REMOVE) {
Slog.d(TAG, "Propagating install state across downgrade");
}
for (int i = 0; i < allUserHandles.length; i++) {
if (DEBUG_REMOVE) {
Slog.d(TAG, " user " + allUserHandles[i]
+ " => " + perUserInstalled[i]);
}
ps.setInstalled(perUserInstalled[i], allUserHandles[i]);
}
}
}
// can downgrade to reader
if (writeSettings) {
// Save settings now
mSettings.writeLPr();//更新packages.xml
}
}
if (outInfo != null) {
// A user ID was deleted here. Go through all users and remove it
// from KeyStore.
removeKeystoreDataIfNeeded(UserHandle.USER_ALL, outInfo.removedAppId);
}我们再来看deleteInstalledPackageLI函数，最后一段代码，
if (deleteCodeAndResources && (outInfo != null)) {
outInfo.args = createInstallArgsForExisting(packageFlagsToInstallFlags(ps),
ps.codePathString, ps.resourcePathString, getAppDexInstructionSets(ps));
if (DEBUG_SD_INSTALL) Slog.i(TAG, "args=" + outInfo.args);
}我们来看下这个函数，如果不是安装在sd卡上，最后新建一个FileInstallArgs对象。
private InstallArgs createInstallArgsForExisting(int installFlags, String codePath,
String resourcePath, String[] instructionSets) {
final boolean isInAsec;
if (installOnExternalAsec(installFlags)) {
/* Apps on SD card are always in ASEC containers. */
isInAsec = true;
} else if (installForwardLocked(installFlags)
&& !codePath.startsWith(mDrmAppPrivateInstallDir.getAbsolutePath())) {
/*
* Forward-locked apps are only in ASEC containers if they're the
* new style
*/
isInAsec = true;
} else {
isInAsec = false;
}
if (isInAsec) {
return new AsecInstallArgs(codePath, instructionSets,
installOnExternalAsec(installFlags), installForwardLocked(installFlags));
} else {
return new FileInstallArgs(codePath, resourcePath, instructionSets);
}
}最后返回到deletePackageX函数，最后调用如下代码，直接到FileInstallArgs的doPostDeleteLI函数。
if (info.args != null) {
synchronized (mInstallLock) {
info.args.doPostDeleteLI(true);
}
}doPostDeleteLI函数如下：
boolean doPostDeleteLI(boolean delete) {
// XXX err, shouldn't we respect the delete flag?
cleanUpResourcesLI();
return true;
}cleanUpResourcesLI函数会删除资源和代码文件，dex文件
void cleanUpResourcesLI() {
// Try enumerating all code paths before deleting
List<String> allCodePaths = Collections.EMPTY_LIST;
if (codeFile != null && codeFile.exists()) {
try {
final PackageLite pkg = PackageParser.parsePackageLite(codeFile, 0);
allCodePaths = pkg.getAllCodePaths();
} catch (PackageParserException e) {
// Ignored; we tried our best
}
}
cleanUp();
removeDexFiles(allCodePaths, instructionSets);
}cleanUp函数就是删除apk文件。
private boolean cleanUp() {
if (codeFile == null || !codeFile.exists()) {
return false;
}
if (codeFile.isDirectory()) {
mInstaller.rmPackageDir(codeFile.getAbsolutePath());
} else {
codeFile.delete();
}
if (resourceFile != null && !FileUtils.contains(codeFile, resourceFile)) {
resourceFile.delete();
}
return true;
}