标签：
在Android系统启动的过程中，系统会通过PackageManagerService来扫描特定的目录，以便可以对保存在里面的apk进行安装。PackageManagerService主要做两件事情：
- 解析这个apk的配置文件AndroidManifest.xml以便获得它的安装信息
- 为这个apk分配Linux用户ID和用户组ID以便apk在系统中可以获取到合适的运行权限
下面我们来开始分析PackageManagerService是如何安装apk并执行上面两件事情的
在前面分析Zygote的时候，有分析到PackageManagerService是由PackageManagerService.main来启动的，因此我们一开始就来分析PackageManagerService.main
public static PackageManagerService main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
PackageManagerService m = new PackageManagerService(context, installer,
factoryTest, onlyCore);
ServiceManager.addService("package", m);
return m;
}这里一开始先把PackageManagerService服务new一个出来，在启动的时候会调用他的构造函数，构造函数里面会对系统中特定的目录以便对保存在里面的apk进行安装。之后将它注册到ServiceManager中，这样就其他组件就可以通过ServiceManager来获得他的访问接口了。
来看看PackageManagerService的构造函数
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
SystemClock.uptimeMillis());
if (mSdkVersion <= 0) {
Slog.w(TAG, "**** ro.build.version.sdk not set!");
}
mContext = context;
mFactoryTest = factoryTest;
mOnlyCore = onlyCore;
mLazyDexOpt = "eng".equals(SystemProperties.get("ro.build.type"));
mMetrics = new DisplayMetrics();
mSettings = new Settings(mPackages);
mSettings.addSharedUserLPw("android.uid.system", Process.SYSTEM_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.phone", RADIO_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.log", LOG_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.nfc", NFC_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.bluetooth", BLUETOOTH_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.shell", SHELL_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
// TODO: add a property to control this?
long dexOptLRUThresholdInMinutes;
if (mLazyDexOpt) {
dexOptLRUThresholdInMinutes = 30; // only last 30 minutes of apps for eng builds.
} else {
dexOptLRUThresholdInMinutes = 7 * 24 * 60; // apps used in the 7 days for users.
}
mDexOptLRUThresholdInMills = dexOptLRUThresholdInMinutes * 60 * 1000;
String separateProcesses = SystemProperties.get("debug.separate_processes");
if (separateProcesses != null && separateProcesses.length() > 0) {
if ("*".equals(separateProcesses)) {
mDefParseFlags = PackageParser.PARSE_IGNORE_PROCESSES;
mSeparateProcesses = null;
Slog.w(TAG, "Running with debug.separate_processes: * (ALL)");
} else {
mDefParseFlags = 0;
mSeparateProcesses = separateProcesses.split(",");
Slog.w(TAG, "Running with debug.separate_processes: "
+ separateProcesses);
}
} else {
mDefParseFlags = 0;
mSeparateProcesses = null;
}
mInstaller = installer;
mPackageDexOptimizer = new PackageDexOptimizer(this);
mMoveCallbacks = new MoveCallbacks(FgThread.get().getLooper());
mOnPermissionChangeListeners = new OnPermissionChangeListeners(
FgThread.get().getLooper());
getDefaultDisplayMetrics(context, mMetrics);
SystemConfig systemConfig = SystemConfig.getInstance();
mGlobalGids = systemConfig.getGlobalGids();
mSystemPermissions = systemConfig.getSystemPermissions();
mAvailableFeatures = systemConfig.getAvailableFeatures();
synchronized (mInstallLock) {
// writer
synchronized (mPackages) {
mHandlerThread = new ServiceThread(TAG,
Process.THREAD_PRIORITY_BACKGROUND, true /*allowIo*/);
mHandlerThread.start();
mHandler = new PackageHandler(mHandlerThread.getLooper());
Watchdog.getInstance().addThread(mHandler, WATCHDOG_TIMEOUT);
File dataDir = Environment.getDataDirectory();
mAppDataDir = new File(dataDir, "data");
mAppInstallDir = new File(dataDir, "app");
mAppLib32InstallDir = new File(dataDir, "app-lib");
mAsecInternalPath = new File(dataDir, "app-asec").getPath();
mUserAppDataDir = new File(dataDir, "user");
mDrmAppPrivateInstallDir = new File(dataDir, "app-private");
sUserManager = new UserManagerService(context, this,
mInstallLock, mPackages);
// Propagate permission configuration in to package manager.
ArrayMap<String, SystemConfig.PermissionEntry> permConfig
= systemConfig.getPermissions();
for (int i=0; i<permConfig.size(); i++) {
SystemConfig.PermissionEntry perm = permConfig.valueAt(i);
BasePermission bp = mSettings.mPermissions.get(perm.name);
if (bp == null) {
bp = new BasePermission(perm.name, "android", BasePermission.TYPE_BUILTIN);
mSettings.mPermissions.put(perm.name, bp);
}
if (perm.gids != null) {
bp.setGids(perm.gids, perm.perUser);
}
}
ArrayMap<String, String> libConfig = systemConfig.getSharedLibraries();
for (int i=0; i<libConfig.size(); i++) {
mSharedLibraries.put(libConfig.keyAt(i),
new SharedLibraryEntry(libConfig.valueAt(i), null));
}
mFoundPolicyFile = SELinuxMMAC.readInstallPolicy();
mRestoredSettings = mSettings.readLPw(this, sUserManager.getUsers(false),
mSdkVersion, mOnlyCore);
String customResolverActivity = Resources.getSystem().getString(
R.string.config_customResolverActivity);
if (TextUtils.isEmpty(customResolverActivity)) {
customResolverActivity = null;
} else {
mCustomResolverComponentName = ComponentName.unflattenFromString(
customResolverActivity);
}
long startTime = SystemClock.uptimeMillis();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
startTime);
// Set flag to monitor and not change apk file paths when
// scanning install directories.
final int scanFlags = SCAN_NO_PATHS | SCAN_DEFER_DEX | SCAN_BOOTING | SCAN_INITIAL;
final ArraySet<String> alreadyDexOpted = new ArraySet<String>();
/**
* Add everything in the in the boot class path to the
* list of process files because dexopt will have been run
* if necessary during zygote startup.
*/
final String bootClassPath = System.getenv("BOOTCLASSPATH");
final String systemServerClassPath = System.getenv("SYSTEMSERVERCLASSPATH");
if (bootClassPath != null) {
String[] bootClassPathElements = splitString(bootClassPath, ‘:‘);
for (String element : bootClassPathElements) {
alreadyDexOpted.add(element);
}
} else {
Slog.w(TAG, "No BOOTCLASSPATH found!");
}
if (systemServerClassPath != null) {
String[] systemServerClassPathElements = splitString(systemServerClassPath, ‘:‘);
for (String element : systemServerClassPathElements) {
alreadyDexOpted.add(element);
}
} else {
Slog.w(TAG, "No SYSTEMSERVERCLASSPATH found!");
}
final List<String> allInstructionSets = InstructionSets.getAllInstructionSets();
final String[] dexCodeInstructionSets =
getDexCodeInstructionSets(
allInstructionSets.toArray(new String[allInstructionSets.size()]));
/**
* Ensure all external libraries have had dexopt run on them.
*/
if (mSharedLibraries.size() > 0) {
// NOTE: For now, we‘re compiling these system "shared libraries"
// (and framework jars) into all available architectures. It‘s possible
// to compile them only when we come across an app that uses them (there‘s
// already logic for that in scanPackageLI) but that adds some complexity.
for (String dexCodeInstructionSet : dexCodeInstructionSets) {
for (SharedLibraryEntry libEntry : mSharedLibraries.values()) {
final String lib = libEntry.path;
if (lib == null) {
continue;
}
try {
int dexoptNeeded = DexFile.getDexOptNeeded(lib, null, dexCodeInstructionSet, false);
if (dexoptNeeded != DexFile.NO_DEXOPT_NEEDED) {
alreadyDexOpted.add(lib);
mInstaller.dexopt(lib, Process.SYSTEM_UID, true, dexCodeInstructionSet, dexoptNeeded, false);
}
} catch (FileNotFoundException e) {
Slog.w(TAG, "Library not found: " + lib);
} catch (IOException e) {
Slog.w(TAG, "Cannot dexopt " + lib + "; is it an APK or JAR? "
+ e.getMessage());
}
}
}
}
File frameworkDir = new File(Environment.getRootDirectory(), "framework");
// Gross hack for now: we know this file doesn‘t contain any
// code, so don‘t dexopt it to avoid the resulting log spew.
alreadyDexOpted.add(frameworkDir.getPath() + "/framework-res.apk");
// Gross hack for now: we know this file is only part of
// the boot class path for art, so don‘t dexopt it to
// avoid the resulting log spew.
alreadyDexOpted.add(frameworkDir.getPath() + "/core-libart.jar");
/**
* There are a number of commands implemented in Java, which
* we currently need to do the dexopt on so that they can be
* run from a non-root shell.
*/
String[] frameworkFiles = frameworkDir.list();
if (frameworkFiles != null) {
// TODO: We could compile these only for the most preferred ABI. We should
// first double check that the dex files for these commands are not referenced
// by other system apps.
for (String dexCodeInstructionSet : dexCodeInstructionSets) {
for (int i=0; i<frameworkFiles.length; i++) {
File libPath = new File(frameworkDir, frameworkFiles[i]);
String path = libPath.getPath();
// Skip the file if we already did it.
if (alreadyDexOpted.contains(path)) {
continue;
}
// Skip the file if it is not a type we want to dexopt.
if (!path.endsWith(".apk") && !path.endsWith(".jar")) {
continue;
}
try {
int dexoptNeeded = DexFile.getDexOptNeeded(path, null, dexCodeInstructionSet, false);
if (dexoptNeeded != DexFile.NO_DEXOPT_NEEDED) {
mInstaller.dexopt(path, Process.SYSTEM_UID, true, dexCodeInstructionSet, dexoptNeeded, false);
}
} catch (FileNotFoundException e) {
Slog.w(TAG, "Jar not found: " + path);
} catch (IOException e) {
Slog.w(TAG, "Exception reading jar: " + path, e);
}
}
}
}
final VersionInfo ver = mSettings.getInternalVersion();
mIsUpgrade = !Build.FINGERPRINT.equals(ver.fingerprint);
// when upgrading from pre-M, promote system app permissions from install to runtime
mPromoteSystemApps =
mIsUpgrade && ver.sdkVersion <= Build.VERSION_CODES.LOLLIPOP_MR1;
// save off the names of pre-existing system packages prior to scanning; we don‘t
// want to automatically grant runtime permissions for new system apps
if (mPromoteSystemApps) {
Iterator<PackageSetting> pkgSettingIter = mSettings.mPackages.values().iterator();
while (pkgSettingIter.hasNext()) {
PackageSetting ps = pkgSettingIter.next();
if (isSystemApp(ps)) {
mExistingSystemPackages.add(ps.name);
}
}
}
// Collect vendor overlay packages.
// (Do this before scanning any apps.)
// For security and version matching reason, only consider
// overlay packages if they reside in VENDOR_OVERLAY_DIR.
File vendorOverlayDir = new File(VENDOR_OVERLAY_DIR);
scanDirLI(vendorOverlayDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags | SCAN_TRUSTED_OVERLAY, 0);
// Find base frameworks (resource packages without code).
scanDirLI(frameworkDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED,
scanFlags | SCAN_NO_DEX, 0);
// Collected privileged system packages.
final File privilegedAppDir = new File(Environment.getRootDirectory(), "priv-app");
scanDirLI(privilegedAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED, scanFlags, 0);
// Collect ordinary system packages.
final File systemAppDir = new File(Environment.getRootDirectory(), "app");
scanDirLI(systemAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);
// Collect all vendor packages.
File vendorAppDir = new File("/vendor/app");
try {
vendorAppDir = vendorAppDir.getCanonicalFile();
} catch (IOException e) {
// failed to look up canonical path, continue with original one
}
scanDirLI(vendorAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);
// Collect all OEM packages.
final File oemAppDir = new File(Environment.getOemDirectory(), "app");
scanDirLI(oemAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);
if (DEBUG_UPGRADE) Log.v(TAG, "Running installd update commands");
mInstaller.moveFiles();
// Prune any system packages that no longer exist.
final List<String> possiblyDeletedUpdatedSystemApps = new ArrayList<String>();
if (!mOnlyCore) {
Iterator<PackageSetting> psit = mSettings.mPackages.values().iterator();
while (psit.hasNext()) {
PackageSetting ps = psit.next();
/*
* If this is not a system app, it can‘t be a
* disable system app.
*/
if ((ps.pkgFlags & ApplicationInfo.FLAG_SYSTEM) == 0) {
continue;
}
/*
* If the package is scanned, it‘s not erased.
*/
final PackageParser.Package scannedPkg = mPackages.get(ps.name);
if (scannedPkg != null) {
/*
* If the system app is both scanned and in the
* disabled packages list, then it must have been
* added via OTA. Remove it from the currently
* scanned package so the previously user-installed
* application can be scanned.
*/
if (mSettings.isDisabledSystemPackageLPr(ps.name)) {
logCriticalInfo(Log.WARN, "Expecting better updated system app for "
+ ps.name + "; removing system app. Last known codePath="
+ ps.codePathString + ", installStatus=" + ps.installStatus
+ ", versionCode=" + ps.versionCode + "; scanned versionCode="
+ scannedPkg.mVersionCode);
removePackageLI(ps, true);
mExpectingBetter.put(ps.name, ps.codePath);
}
continue;
}
if (!mSettings.isDisabledSystemPackageLPr(ps.name)) {
psit.remove();
logCriticalInfo(Log.WARN, "System package " + ps.name
+ " no longer exists; wiping its data");
removeDataDirsLI(null, ps.name);
} else {
final PackageSetting disabledPs = mSettings.getDisabledSystemPkgLPr(ps.name);
if (disabledPs.codePath == null || !disabledPs.codePath.exists()) {
possiblyDeletedUpdatedSystemApps.add(ps.name);
}
}
}
}
//look for any incomplete package installations
ArrayList<PackageSetting> deletePkgsList = mSettings.getListOfIncompleteInstallPackagesLPr();
//clean up list
for(int i = 0; i < deletePkgsList.size(); i++) {
//clean up here
cleanupInstallFailedPackage(deletePkgsList.get(i));
}
//delete tmp files
deleteTempPackageFiles();
// Remove any shared userIDs that have no associated packages
mSettings.pruneSharedUsersLPw();
if (!mOnlyCore) {
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
SystemClock.uptimeMillis());
scanDirLI(mAppInstallDir, 0, scanFlags | SCAN_REQUIRE_KNOWN, 0);
scanDirLI(mDrmAppPrivateInstallDir, PackageParser.PARSE_FORWARD_LOCK,
scanFlags | SCAN_REQUIRE_KNOWN, 0);
/**
* Remove disable package settings for any updated system
* apps that were removed via an OTA. If they‘re not a
* previously-updated app, remove them completely.
* Otherwise, just revoke their system-level permissions.
*/
for (String deletedAppName : possiblyDeletedUpdatedSystemApps) {
PackageParser.Package deletedPkg = mPackages.get(deletedAppName);
mSettings.removeDisabledSystemPackageLPw(deletedAppName);
String msg;
if (deletedPkg == null) {
msg = "Updated system package " + deletedAppName
+ " no longer exists; wiping its data";
removeDataDirsLI(null, deletedAppName);
} else {
msg = "Updated system app + " + deletedAppName
+ " no longer present; removing system privileges for "
+ deletedAppName;
deletedPkg.applicationInfo.flags &= ~ApplicationInfo.FLAG_SYSTEM;
PackageSetting deletedPs = mSettings.mPackages.get(deletedAppName);
deletedPs.pkgFlags &= ~ApplicationInfo.FLAG_SYSTEM;
}
logCriticalInfo(Log.WARN, msg);
}
/**
* Make sure all system apps that we expected to appear on
* the userdata partition actually showed up. If they never
* appeared, crawl back and revive the system version.
*/
for (int i = 0; i < mExpectingBetter.size(); i++) {
final String packageName = mExpectingBetter.keyAt(i);
if (!mPackages.containsKey(packageName)) {
final File scanFile = mExpectingBetter.valueAt(i);
logCriticalInfo(Log.WARN, "Expected better " + packageName
+ " but never showed up; reverting to system");
final int reparseFlags;
if (FileUtils.contains(privilegedAppDir, scanFile)) {
reparseFlags = PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED;
} else if (FileUtils.contains(systemAppDir, scanFile)) {
reparseFlags = PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR;
} else if (FileUtils.contains(vendorAppDir, scanFile)) {
reparseFlags = PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR;
} else if (FileUtils.contains(oemAppDir, scanFile)) {
reparseFlags = PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR;
} else {
Slog.e(TAG, "Ignoring unexpected fallback path " + scanFile);
continue;
}
mSettings.enableSystemPackageLPw(packageName);
try {
scanPackageLI(scanFile, reparseFlags, scanFlags, 0, null);
} catch (PackageManagerException e) {
Slog.e(TAG, "Failed to parse original system package: "
+ e.getMessage());
}
}
}
}
mExpectingBetter.clear();
// Now that we know all of the shared libraries, update all clients to have
// the correct library paths.
updateAllSharedLibrariesLPw();
for (SharedUserSetting setting : mSettings.getAllSharedUsersLPw()) {
// NOTE: We ignore potential failures here during a system scan (like
// the rest of the commands above) because there‘s precious little we
// can do about it. A settings error is reported, though.
adjustCpuAbisForSharedUserLPw(setting.packages, null /* scanned package */,
false /* force dexopt */, false /* defer dexopt */,
false /* boot complete */);
}
// Now that we know all the packages we are keeping,
// read and update their last usage times.
mPackageUsage.readLP();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
Slog.i(TAG, "Time to scan packages: "
+ ((SystemClock.uptimeMillis()-startTime)/1000f)
+ " seconds");
// If the platform SDK has changed since the last time we booted,
// we need to re-grant app permission to catch any new ones that
// appear. This is really a hack, and means that apps can in some
// cases get permissions that the user didn‘t initially explicitly
// allow... it would be nice to have some better way to handle
// this situation.
int updateFlags = UPDATE_PERMISSIONS_ALL;
if (ver.sdkVersion != mSdkVersion) {
Slog.i(TAG, "Platform changed from " + ver.sdkVersion + " to "
+ mSdkVersion + "; regranting permissions for internal storage");
updateFlags |= UPDATE_PERMISSIONS_REPLACE_PKG | UPDATE_PERMISSIONS_REPLACE_ALL;
}
updatePermissionsLPw(null, null, StorageManager.UUID_PRIVATE_INTERNAL, updateFlags);
ver.sdkVersion = mSdkVersion;
// If this is the first boot or an update from pre-M, and it is a normal
// boot, then we need to initialize the default preferred apps across
// all defined users.
if (!onlyCore && (mPromoteSystemApps || !mRestoredSettings)) {
for (UserInfo user : sUserManager.getUsers(true)) {
mSettings.applyDefaultPreferredAppsLPw(this, user.id);
applyFactoryDefaultBrowserLPw(user.id);
primeDomainVerificationsLPw(user.id);
}
}
// If this is first boot after an OTA, and a normal boot, then
// we need to clear code cache directories.
if (mIsUpgrade && !onlyCore) {
Slog.i(TAG, "Build fingerprint changed; clearing code caches");
for (int i = 0; i < mSettings.mPackages.size(); i++) {
final PackageSetting ps = mSettings.mPackages.valueAt(i);
if (Objects.equals(StorageManager.UUID_PRIVATE_INTERNAL, ps.volumeUuid)) {
deleteCodeCacheDirsLI(ps.volumeUuid, ps.name);
}
}
ver.fingerprint = Build.FINGERPRINT;
}
checkDefaultBrowser();
// clear only after permissions and other defaults have been updated
mExistingSystemPackages.clear();
mPromoteSystemApps = false;
// All the changes are done during package scanning.
ver.databaseVersion = Settings.CURRENT_DATABASE_VERSION;
// can downgrade to reader
mSettings.writeLPr();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
mRequiredVerifierPackage = getRequiredVerifierLPr();
mRequiredInstallerPackage = getRequiredInstallerLPr();
mInstallerService = new PackageInstallerService(context, this);
mIntentFilterVerifierComponent = getIntentFilterVerifierComponentNameLPr();
mIntentFilterVerifier = new IntentVerifierProxy(mContext,
mIntentFilterVerifierComponent);
} // synchronized (mPackages)
} // synchronized (mInstallLock)
// Now after opening every single application zip, make sure they
// are all flushed. Not really needed, but keeps things nice and
// tidy.
Runtime.getRuntime().gc();
// Expose private service for system components to use.
LocalServices.addService(PackageManagerInternal.class, new PackageManagerInternalImpl());
}这段代码很长，不过其实其逻辑也很是很简单的。其中有个类型为Settings的成员变量mSettings，这是用来管理apk安装信息的，假如Apk安装了，那么Settings就会记录下他的信息，下次再碰到要安装这个apk的时候直接调用之前保存的信息就可以了。这个操作是由Settings.readLPw操作来完成的。
接着使用scanDirLI来安装保存在/system/framework、/system/app、/vendor/app、/data/app、/data/app-private中的apk。
安装完之后就调用updatePermissionsLPw来申请为了特定的资源访问权限的apk分配相应的linux用户组ID。
最后调用Settings.readLPw将之前获得的权限和apk安装信息保存到本地的一个配置文件中，以便下次在安装这些apk的时候，就可以将需要的apk信息很快速的恢复回来。
接着我们来一一分析这几个函数
boolean readLPw(PackageManagerService service, List<UserInfo> users, int sdkVersion,
boolean onlyCore) {
FileInputStream str = null;
if (mBackupSettingsFilename.exists()) {
try {
str = new FileInputStream(mBackupSettingsFilename);
}
} catch (java.io.IOException e) {
// We‘ll try for the normal settings file.
}
}
mPendingPackages.clear();
mPastSignatures.clear();
mKeySetRefs.clear();
try {
if (str == null) {
if (!mSettingsFilename.exists()) {
return false;
}
str = new FileInputStream(mSettingsFilename);
}
XmlPullParser parser = Xml.newPullParser();
parser.setInput(str, StandardCharsets.UTF_8.name());
int type;
int outerDepth = parser.getDepth();
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
String tagName = parser.getName();
if (tagName.equals("package")) {
readPackageLPw(parser);
}
...
} else if (tagName.equals("shared-user")) {
readSharedUserLPw(parser);
}
}
str.close();
} catch (XmlPullParserException e) {
...
} catch (java.io.IOException e) {
...
}
return true;
}这里是主要是针对packages.xml和packages-backup.xml，第一个是保存的上一次的apk安装信息，第二个是备份前一个的文件。通过XmlPullParser将安装信息写入这个两个xml文件，具体什么信息就不关心了，主要看看用户ID相关的信息就好了。通过调用readPackageLPw来获取用户ID。接着调用readSharedUserLPw来获取上一次安装这个apk时分配过来的用户ID。
private void scanDirLI(File dir, int parseFlags, int scanFlags, long currentTime) {
final File[] files = dir.listFiles();
if (ArrayUtils.isEmpty(files)) {
Log.d(TAG, "No files in app dir " + dir);
return;
}
if (DEBUG_PACKAGE_SCANNING) {
Log.d(TAG, "Scanning app dir " + dir + " scanFlags=" + scanFlags
+ " flags=0x" + Integer.toHexString(parseFlags));
}
for (File file : files) {
final boolean isPackage = (isApkFile(file) || file.isDirectory())
&& !PackageInstallerService.isStageName(file.getName());
if (!isPackage) {
// Ignore entries which are not packages
continue;
}
try {
scanPackageLI(file, parseFlags | PackageParser.PARSE_MUST_BE_APK,
scanFlags, currentTime, null);
} catch (PackageManagerException e) {
Slog.w(TAG, "Failed to parse " + file + ": " + e.getMessage());
// Delete invalid userdata apps
if ((parseFlags & PackageParser.PARSE_IS_SYSTEM) == 0 &&
e.error == PackageManager.INSTALL_FAILED_INVALID_APK) {
logCriticalInfo(Log.WARN, "Deleting invalid package at " + file);
if (file.isDirectory()) {
mInstaller.rmPackageDir(file.getAbsolutePath());
} else {
file.delete();
}
}
}
}
}先循环检测参数dir所描述的一个目录中的每一个文件。检测到以”.apk”结尾的文件后，就调用scanPackageLI来对他们进行解析，解析完后就会返回一个Package对象pkg。
如果scanPackageLI发现他检测的apk不是一个真正的apk的话，就会删除它。
private void updatePermissionsLPw(String changingPkg, PackageParser.Package pkgInfo,
int flags) {
final String volumeUuid = (pkgInfo != null) ? getVolumeUuidForPackage(pkgInfo) : null;
updatePermissionsLPw(changingPkg, pkgInfo, volumeUuid, flags);
}
private void updatePermissionsLPw(String changingPkg,
PackageParser.Package pkgInfo, String replaceVolumeUuid, int flags) {
// Make sure there are no dangling permission trees.
Iterator<BasePermission> it = mSettings.mPermissionTrees.values().iterator();
while (it.hasNext()) {
final BasePermission bp = it.next();
if (bp.packageSetting == null) {
// We may not yet have parsed the package, so just see if
// we still know about its settings.
bp.packageSetting = mSettings.mPackages.get(bp.sourcePackage);
}
if (bp.packageSetting == null) {
Slog.w(TAG, "Removing dangling permission tree: " + bp.name
+ " from package " + bp.sourcePackage);
it.remove();
} else if (changingPkg != null && changingPkg.equals(bp.sourcePackage)) {
if (pkgInfo == null || !hasPermission(pkgInfo, bp.name)) {
Slog.i(TAG, "Removing old permission tree: " + bp.name
+ " from package " + bp.sourcePackage);
flags |= UPDATE_PERMISSIONS_ALL;
it.remove();
}
}
}
// Make sure all dynamic permissions have been assigned to a package,
// and make sure there are no dangling permissions.
it = mSettings.mPermissions.values().iterator();
while (it.hasNext()) {
final BasePermission bp = it.next();
if (bp.type == BasePermission.TYPE_DYNAMIC) {
if (DEBUG_SETTINGS) Log.v(TAG, "Dynamic permission: name="
+ bp.name + " pkg=" + bp.sourcePackage
+ " info=" + bp.pendingInfo);
if (bp.packageSetting == null && bp.pendingInfo != null) {
final BasePermission tree = findPermissionTreeLP(bp.name);
if (tree != null && tree.perm != null) {
bp.packageSetting = tree.packageSetting;
bp.perm = new PackageParser.Permission(tree.perm.owner,
new PermissionInfo(bp.pendingInfo));
bp.perm.info.packageName = tree.perm.info.packageName;
bp.perm.info.name = bp.name;
bp.uid = tree.uid;
}
}
}
if (bp.packageSetting == null) {
// We may not yet have parsed the package, so just see if
// we still know about its settings.
bp.packageSetting = mSettings.mPackages.get(bp.sourcePackage);
}
if (bp.packageSetting == null) {
Slog.w(TAG, "Removing dangling permission: " + bp.name
+ " from package " + bp.sourcePackage);
it.remove();
} else if (changingPkg != null && changingPkg.equals(bp.sourcePackage)) {
if (pkgInfo == null || !hasPermission(pkgInfo, bp.name)) {
Slog.i(TAG, "Removing old permission: " + bp.name
+ " from package " + bp.sourcePackage);
flags |= UPDATE_PERMISSIONS_ALL;
it.remove();
}
}
}
// Now update the permissions for all packages, in particular
// replace the granted permissions of the system packages.
if ((flags&UPDATE_PERMISSIONS_ALL) != 0) {
for (PackageParser.Package pkg : mPackages.values()) {
if (pkg != pkgInfo) {
// Only replace for packages on requested volume
final String volumeUuid = getVolumeUuidForPackage(pkg);
final boolean replace = ((flags & UPDATE_PERMISSIONS_REPLACE_ALL) != 0)
&& Objects.equals(replaceVolumeUuid, volumeUuid);
grantPermissionsLPw(pkg, replace, changingPkg);
}
}
}
if (pkgInfo != null) {
// Only replace for packages on requested volume
final String volumeUuid = getVolumeUuidForPackage(pkgInfo);
final boolean replace = ((flags & UPDATE_PERMISSIONS_REPLACE_PKG) != 0)
&& Objects.equals(replaceVolumeUuid, volumeUuid);
grantPermissionsLPw(pkgInfo, replace, changingPkg);
}
}mPackages里面保存了所有安装的apk，接着调用grantPermissionsLPw来分配他们的Linux用户组ID，以便他们可以获得所申请的资源访问权限。
至此系统启动时的apk安装过程分析就结束了，至于启动后再安装的过程也是类似的，只是换了一个安装入口。
标签：
原文地址：http://blog.csdn.net/zhoulei0623/article/details/51942041
