Apk安装的主要步骤:
为了学习这个过程,真的是陷入了pms的源码很久,也看了很多前人的博文,才算是有了些思路,所以此处先把主要步骤列出来,后面再慢慢分析细节。
将apk文件复制到
data/app目录解析apk信息
dexopt操作
更新权限信息
完成安装,发送
Intent.ACTION_PACKAGE_ADDED广播
下面将具体步骤列张图出来:
Paste_Image.png
由图可见安装过程中流转的步骤还是比较多的,下面具体分析
1. 将apk文件copy至data/app目录
1.1 installPackageAsUser
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.INSTALL_PACKAGES, null); final int callingUid = Binder.getCallingUid();
...
... if ((callingUid == Process.SHELL_UID) || (callingUid == Process.ROOT_UID)) {
installFlags |= PackageManager.INSTALL_FROM_ADB;
} else { // Caller holds INSTALL_PACKAGES permission, so we're less strict
// about installerPackageName.
installFlags &= ~PackageManager.INSTALL_FROM_ADB;
installFlags &= ~PackageManager.INSTALL_ALL_USERS;
}
UserHandle user; if ((installFlags & PackageManager.INSTALL_ALL_USERS) != 0) {
user = UserHandle.ALL;
} else {
user = new UserHandle(userId);
}
verificationParams.setInstallerUid(callingUid); final File originFile = new File(originPath); final OriginInfo origin = OriginInfo.fromUntrustedFile(originFile); final Message msg = mHandler.obtainMessage(INIT_COPY);
msg.obj = new InstallParams(origin, observer, installFlags,
installerPackageName, verificationParams, user, packageAbiOverride);
mHandler.sendMessage(msg);这个方法主要是判断安装来源,包括adb,shell,all_user,然后向PMS的mHandler发送INIT_COPY的消息,这个mHandler运行在一个HandlerThread中。
1.2 handleMessage(INIT_COPY)&handleMessage(MCS_BOUND)
case INIT_COPY:{
HandlerParams params = (HandlerParams) msg.obj; int idx = mPendingInstalls.size(); if (DEBUG_INSTALL) Slog.i(TAG, "init_copy idx=" + idx + ": " + params); // If a bind was already initiated we dont really
// need to do anything. The pending install
// will be processed later on.
if (!mBound) { // If this is the only one pending we might
// have to bind to the service again.
if (!connectToService()) {
Slog.e(TAG, "Failed to bind to media container service");
params.serviceError(); return;
} else { // Once we bind to the service, the first
// pending request will be processed.
mPendingInstalls.add(idx, params);
}
} else {
mPendingInstalls.add(idx, params); // Already bound to the service. Just make
// sure we trigger off processing the first request.
if (idx == 0) {
mHandler.sendEmptyMessage(MCS_BOUND);
}
}
}case MCS_BOUND:{
...
...
HandlerParams params = mPendingInstalls.get(0); if (params != null) { if (params.startCopy()) { // We are done... look for more work or to
// go idle.
if (DEBUG_SD_INSTALL) Log.i(TAG, "Checking for more work or unbind..."); // Delete pending install
if (mPendingInstalls.size() > 0) {
mPendingInstalls.remove(0);
} if (mPendingInstalls.size() == 0) { if (mBound) { if (DEBUG_SD_INSTALL) Log.i(TAG, "Posting delayed MCS_UNBIND");
removeMessages(MCS_UNBIND);
Message ubmsg = obtainMessage(MCS_UNBIND); // Unbind after a little delay, to avoid
// continual thrashing.
sendMessageDelayed(ubmsg, 10000);
}
...
...
}INIT_COPY主要是确保DefaultContainerService已bound,DefaultContainerService是一个应用服务，具体负责实现APK等相关资源文件在内部或外部存储器上的存储工作。而MCS_BOUND中则执行了params.startCopy()这句,也是最关键的开始copy文件。
1.3 HandlerParams.startCopy
final boolean startCopy() { boolean res; try { if (DEBUG_INSTALL) Slog.i(TAG, "startCopy " + mUser + ": " + this); if (++mRetries > MAX_RETRIES) {
Slog.w(TAG, "Failed to invoke remote methods on default container service. Giving up");
mHandler.sendEmptyMessage(MCS_GIVE_UP);
handleServiceError(); return false;
} else {
handleStartCopy();
res = true;
}
} catch (RemoteException e) { if (DEBUG_INSTALL) Slog.i(TAG, "Posting install MCS_RECONNECT");
mHandler.sendEmptyMessage(MCS_RECONNECT);
res = false;
}
handleReturnCode(); return res;
}该方法中除了检查重试次数外只是简单的调用了handleStartCopy()及handleReturnCode()方法.
1.4 handleStartCopy()
这个方法内容非常多,下面只列出些核心部分
public void handleStartCopy() throws RemoteException { int ret = PackageManager.INSTALL_SUCCEEDED;
...
... final boolean onSd = (installFlags & PackageManager.INSTALL_EXTERNAL) != 0; final boolean onInt = (installFlags & PackageManager.INSTALL_INTERNAL) != 0;
PackageInfoLite pkgLite = null; if (onInt && onSd) { // Check if both bits are set.
Slog.w(TAG, "Conflicting flags specified for installing on both internal and external");
ret = PackageManager.INSTALL_FAILED_INVALID_INSTALL_LOCATION;
} else {
pkgLite = mContainerService.getMinimalPackageInfo(origin.resolvedPath, installFlags,
packageAbiOverride); /*
* If we have too little free space, try to free cache
* before giving up.
*/
if (!origin.staged && pkgLite.recommendedInstallLocation
== PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE) { final StorageManager storage = StorageManager.from(mContext); final long lowThreshold = storage.getStorageLowBytes(
Environment.getDataDirectory()); final long sizeBytes = mContainerService.calculateInstalledSize(
origin.resolvedPath, isForwardLocked(), packageAbiOverride); if (mInstaller.freeCache(sizeBytes + lowThreshold) >= 0) {
pkgLite = mContainerService.getMinimalPackageInfo(origin.resolvedPath,
installFlags, packageAbiOverride);
}
}
}
...
...
* No package verification is enabled, so immediately start
* the remote call to initiate copy using temporary file.
*/
ret = args.copyApk(mContainerService, true);
}
mRet = ret;
}handleStartCopy的核心就是copyApk,其他的都是些存储空间检查,权限检查等等安全校验
2 .解析apk信息
完成apk copy到data/app目录的操作后,下一步就到了 handleReturnCode,这个方法又跳转到processPendingInstall()方法,下面先来看看processPendingInstall()方法:
2.1 processPendingInstall()
private void processPendingInstall(final InstallArgs args, final int currentStatus) { // Queue up an async operation since the package installation may take a little while.
mHandler.post(new Runnable() { public void run() {
mHandler.removeCallbacks(this); // Result object to be returned
PackageInstalledInfo res = new PackageInstalledInfo();
res.returnCode = currentStatus;
res.uid = -1;
res.pkg = null;
res.removedInfo = new PackageRemovedInfo(); if (res.returnCode == PackageManager.INSTALL_SUCCEEDED) {
args.doPreInstall(res.returnCode); synchronized (mInstallLock) {
installPackageLI(args, res); //1.安装
}
args.doPostInstall(res.returnCode, res.uid);
} // A restore should be performed at this point if (a) the install
// succeeded, (b) the operation is not an update, and (c) the new
// package has not opted out of backup participation.
final boolean update = res.removedInfo.removedPackage != null; final int flags = (res.pkg == null) ? 0 : res.pkg.applicationInfo.flags; boolean doRestore = !update
&& ((flags & ApplicationInfo.FLAG_ALLOW_BACKUP) != 0); // Set up the post-install work request bookkeeping. This will be used
// and cleaned up by the post-install event handling regardless of whether
// there's a restore pass performed. Token values are >= 1.
int token; if (mNextInstallToken < 0) mNextInstallToken = 1;
token = mNextInstallToken++;
PostInstallData data = new PostInstallData(args, res);
mRunningInstalls.put(token, data); if (DEBUG_INSTALL) Log.v(TAG, "+ starting restore round-trip " + token); if (res.returnCode == PackageManager.INSTALL_SUCCEEDED && doRestore) { // Pass responsibility to the Backup Manager. It will perform a
// restore if appropriate, then pass responsibility back to the
// Package Manager to run the post-install observer callbacks
// and broadcasts.
IBackupManager bm = IBackupManager.Stub.asInterface(
ServiceManager.getService(Context.BACKUP_SERVICE)); if (bm != null) { if (DEBUG_INSTALL) Log.v(TAG, "token " + token
+ " to BM for possible restore"); try {
bm.restoreAtInstall(res.pkg.applicationInfo.packageName, token); //2.调用backup服务
} catch (RemoteException e) { // can't happen; the backup manager is local
} catch (Exception e) {
Slog.e(TAG, "Exception trying to enqueue restore", e);
doRestore = false;
}
} else {
Slog.e(TAG, "Backup Manager not found!");
doRestore = false;
}
} if (!doRestore) { // No restore possible, or the Backup Manager was mysteriously not
// available -- just fire the post-install work request directly.
if (DEBUG_INSTALL) Log.v(TAG, "No restore - queue post-install for " + token);
Message msg = mHandler.obtainMessage(POST_INSTALL, token, 0);
mHandler.sendMessage(msg);
}
}
});
}这个方法有几个关键步骤,一是installPackageLI(args, res);,这个方法具体执行了解析package和后续操作,而再installPackageLI(args, res);执行完毕后会走到bm.restoreAtInstall(res.pkg.applicationInfo.packageName, token);,会调用backupservice的restoreAtInstall方法,而restoreAtInstall方法最终又会调用PMS的finishPackageInstall()方法,完成安装。
2.2 installPackageLI(args, res)
private void installPackageLI(InstallArgs args, PackageInstalledInfo res) { final int installFlags = args.installFlags;
String installerPackageName = args.installerPackageName;
File tmpPackageFile = new File(args.getCodePath()); boolean forwardLocked = ((installFlags & PackageManager.INSTALL_FORWARD_LOCK) != 0); boolean onSd = ((installFlags & PackageManager.INSTALL_EXTERNAL) != 0); boolean replace = false; final int scanFlags = SCAN_NEW_INSTALL | SCAN_FORCE_DEX | SCAN_UPDATE_SIGNATURE; // Result object to be returned
res.returnCode = PackageManager.INSTALL_SUCCEEDED; if (DEBUG_INSTALL) Slog.d(TAG, "installPackageLI: path=" + tmpPackageFile); // Retrieve PackageSettings and parse package
final int parseFlags = mDefParseFlags | PackageParser.PARSE_CHATTY
| (forwardLocked ? PackageParser.PARSE_FORWARD_LOCK : 0)
| (onSd ? PackageParser.PARSE_ON_SDCARD : 0);
PackageParser pp = new PackageParser();
pp.setSeparateProcesses(mSeparateProcesses);
pp.setDisplayMetrics(mMetrics); final PackageParser.Package pkg; try {
pkg = pp.parsePackage(tmpPackageFile, parseFlags);
} catch (PackageParserException e) {
res.setError("Failed parse during installPackageLI", e); return;
} // Mark that we have an install time CPU ABI override.
pkg.cpuAbiOverride = args.abiOverride;
String pkgName = res.name = pkg.packageName; if ((pkg.applicationInfo.flags&ApplicationInfo.FLAG_TEST_ONLY) != 0) { if ((installFlags & PackageManager.INSTALL_ALLOW_TEST) == 0) {
res.setError(INSTALL_FAILED_TEST_ONLY, "installPackageLI"); return;
}
} try {
pp.collectCertificates(pkg, parseFlags);
pp.collectManifestDigest(pkg);
} catch (PackageParserException e) {
res.setError("Failed collect during installPackageLI", e); return;
} /* If the installer passed in a manifest digest, compare it now. */
if (args.manifestDigest != null) { if (DEBUG_INSTALL) { final String parsedManifest = pkg.manifestDigest == null ? "null"
: pkg.manifestDigest.toString();
Slog.d(TAG, "Comparing manifests: " + args.manifestDigest.toString() + " vs. "
+ parsedManifest);
} if (!args.manifestDigest.equals(pkg.manifestDigest)) {
res.setError(INSTALL_FAILED_PACKAGE_CHANGED, "Manifest digest changed"); return;
}
} else if (DEBUG_INSTALL) { final String parsedManifest = pkg.manifestDigest == null
? "null" : pkg.manifestDigest.toString();
Slog.d(TAG, "manifestDigest was not present, but parser got: " + parsedManifest);
} // Get rid of all references to package scan path via parser.
pp = null;
String oldCodePath = null; boolean systemApp = false; synchronized (mPackages) { // Check whether the newly-scanned package wants to define an already-defined perm
int N = pkg.permissions.size(); for (int i = N-1; i >= 0; i--) {
PackageParser.Permission perm = pkg.permissions.get(i);
BasePermission bp = mSettings.mPermissions.get(perm.info.name); if (bp != null) { // If the defining package is signed with our cert, it's okay. This
// also includes the "updating the same package" case, of course.
// "updating same package" could also involve key-rotation.
final boolean sigsOk; if (!bp.sourcePackage.equals(pkg.packageName)
|| !(bp.packageSetting instanceof PackageSetting)
|| !bp.packageSetting.keySetData.isUsingUpgradeKeySets()
|| ((PackageSetting) bp.packageSetting).sharedUser != null) {
sigsOk = compareSignatures(bp.packageSetting.signatures.mSignatures,
pkg.mSignatures) == PackageManager.SIGNATURE_MATCH;
} else {
sigsOk = checkUpgradeKeySetLP((PackageSetting) bp.packageSetting, pkg);
} if (!sigsOk) { // If the owning package is the system itself, we log but allow
// install to proceed; we fail the install on all other permission
// redefinitions.
if (!bp.sourcePackage.equals("android")) {
res.setError(INSTALL_FAILED_DUPLICATE_PERMISSION, "Package "
+ pkg.packageName + " attempting to redeclare permission "
+ perm.info.name + " already owned by " + bp.sourcePackage);
res.origPermission = perm.info.name;
res.origPackage = bp.sourcePackage; return;
} else {
Slog.w(TAG, "Package " + pkg.packageName
+ " attempting to redeclare system permission "
+ perm.info.name + "; ignoring new declaration");
pkg.permissions.remove(i);
}
}
}
} // Check if installing already existing package
if ((installFlags & PackageManager.INSTALL_REPLACE_EXISTING) != 0) {
String oldName = mSettings.mRenamedPackages.get(pkgName); if (pkg.mOriginalPackages != null
&& pkg.mOriginalPackages.contains(oldName)
&& mPackages.containsKey(oldName)) { // This package is derived from an original package,
// and this device has been updating from that original
// name. We must continue using the original name, so
// rename the new package here.
pkg.setPackageName(oldName);
pkgName = pkg.packageName;
replace = true; if (DEBUG_INSTALL) Slog.d(TAG, "Replacing existing renamed package: oldName="
+ oldName + " pkgName=" + pkgName);
} else if (mPackages.containsKey(pkgName)) { // This package, under its official name, already exists
// on the device; we should replace it.
replace = true; if (DEBUG_INSTALL) Slog.d(TAG, "Replace existing pacakge: " + pkgName);
}
}
PackageSetting ps = mSettings.mPackages.get(pkgName); if (ps != null) { if (DEBUG_INSTALL) Slog.d(TAG, "Existing package: " + ps);
oldCodePath = mSettings.mPackages.get(pkgName).codePathString; if (ps.pkg != null && ps.pkg.applicationInfo != null) {
systemApp = (ps.pkg.applicationInfo.flags &
ApplicationInfo.FLAG_SYSTEM) != 0;
}
res.origUsers = ps.queryInstalledUsers(sUserManager.getUserIds(), true);
}
} if (systemApp && onSd) { // Disable updates to system apps on sdcard
res.setError(INSTALL_FAILED_INVALID_INSTALL_LOCATION, "Cannot install updates to system apps on sdcard"); return;
} if (!args.doRename(res.returnCode, pkg, oldCodePath)) {
res.setError(INSTALL_FAILED_INSUFFICIENT_STORAGE, "Failed rename"); return;
} if (replace) {
replacePackageLI(pkg, parseFlags, scanFlags | SCAN_REPLACING, args.user,
installerPackageName, res);
} else {
installNewPackageLI(pkg, parseFlags, scanFlags | SCAN_DELETE_DATA_ON_FAILURES,
args.user, installerPackageName, res);
} synchronized (mPackages) { final PackageSetting ps = mSettings.mPackages.get(pkgName); if (ps != null) {
res.newUsers = ps.queryInstalledUsers(sUserManager.getUserIds(), true);
}
}
}这个方法先是解析了package包,然后做了大量签名和权限校验的工作,最终会走到
if (replace) {
replacePackageLI(pkg, parseFlags, scanFlags | SCAN_REPLACING, args.user,
installerPackageName, res);
} else {
installNewPackageLI(pkg, parseFlags, scanFlags | SCAN_DELETE_DATA_ON_FAILURES,
args.user, installerPackageName, res);
}这两个方法分别是覆盖安装和安装新应用对应的具体执行.我们来看看installNewPackageLI()
2.3 installNewPackageLI()
private void installNewPackageLI(PackageParser.Package pkg, int parseFlags, int scanFlags, UserHandle user,
String installerPackageName, PackageInstalledInfo res) { // Remember this for later, in case we need to rollback this install
String pkgName = pkg.packageName; if (DEBUG_INSTALL) Slog.d(TAG, "installNewPackageLI: " + pkg); boolean dataDirExists = getDataPathForPackage(pkg.packageName, 0).exists(); synchronized(mPackages) { if (mSettings.mRenamedPackages.containsKey(pkgName)) { // A package with the same name is already installed, though
// it has been renamed to an older name. The package we
// are trying to install should be installed as an update to
// the existing one, but that has not been requested, so bail.
res.setError(INSTALL_FAILED_ALREADY_EXISTS, "Attempt to re-install " + pkgName
+ " without first uninstalling package running as "
+ mSettings.mRenamedPackages.get(pkgName)); return;
} if (mPackages.containsKey(pkgName)) { // Don't allow installation over an existing package with the same name.
res.setError(INSTALL_FAILED_ALREADY_EXISTS, "Attempt to re-install " + pkgName
+ " without first uninstalling."); return;
}
} try {
PackageParser.Package newPackage = scanPackageLI(pkg, parseFlags, scanFlags,
System.currentTimeMillis(), user);
updateSettingsLI(newPackage, installerPackageName, null, null, res); // delete the partially installed application. the data directory will have to be
// restored if it was already existing
if (res.returnCode != PackageManager.INSTALL_SUCCEEDED) { // remove package from internal structures. Note that we want deletePackageX to
// delete the package data and cache directories that it created in
// scanPackageLocked, unless those directories existed before we even tried to
// install.
deletePackageLI(pkgName, UserHandle.ALL, false, null, null,
dataDirExists ? PackageManager.DELETE_KEEP_DATA : 0,
res.removedInfo, true);
}
} catch (PackageManagerException e) {
res.setError("Package couldn't be installed in " + pkg.codePath, e);
}
}这个方法核心的步骤有两个:
PackageParser.Package newPackage = scanPackageLI(pkg, parseFlags, scanFlags,System.currentTimeMillis(), user);updateSettingsLI(newPackage, installerPackageName, null, null, res);
scanPackageLI负责安装,而updateSettingLI则是完成安装后的设置信息更新
2.4 scanPackageLI()
scanPackageLI()方法主要逻辑是由scanPackageDirtyLI()实现的,scanPackageDirtyLI()实在太长了,此处就不列出了,主要说下,这个方法实现了以下操作:
设置系统App的一些参数
校验签名
解析app的provider,校验是否与已有的provider冲突
32/64位abi的一些设置
四大组件的解析，注册
scanPackageDirtyLI()里面的操作确实是太多了，并不止这几点。如需更详细的信息还请查看源码。
另一方面，这个方法里,会调用到performDexOptLI(),其会去执行dexopt操作。
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