【中级——高级迈不过去？】Android高级工程师进阶学习——Android-Apk安装过程

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 © 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。

3. dexopt操作

Apk文件其实只是一个归档zip压缩包,而我们编写的代码最终都编译成了.dex文件,但为了提高运行性能,android系统并不会直接执行.dex,而是会在安装过程中执行dexopt操作来优化.dex文件,最终android系统执行的时优化后的’odex’文件(注意:这个odex文件的后缀也是.dex,其路径在data/dalvik-cache)。对于dalvik虚拟机,dexopt就是优化操作,而对于art虚拟机,dexopt执行的则是dex2oat操作,既将.dex文件翻译成oat文件。关于art和dex2oat的更多信息请看后文。

这里我们先来看看PMS的dexopt操作:

3.1 performDexOptLI()

这个方法的核心是

final int ret = mInstaller.dexopt(path, sharedGid, !isForwardLocked(pkg), pkg.packageName, dexCodeInstructionSet, vmSafeMode);

其作用就是调用PMS的mInstaller成员变量的dexopt操作。

3.2 Installer.dexopt

Installer类的dexopt方法又调用InstallerConnection类的dexopt方法,来看看这个方法:

public int dexopt(String apkPath, int uid, boolean isPublic, String pkgName,
String instructionSet, boolean vmSafeMode) {
StringBuilder builder = new StringBuilder(“dexopt”);
builder.append(’ ‘);
builder.append(apkPath);
builder.append(’ ‘);
builder.append(uid);
builder.append(isPublic ? " 1" : " 0");
builder.append(’ ‘);
builder.append(pkgName);
builder.append(’ ‘);
builder.append(instructionSet);
builder.append(’ ');
builder.append(vmSafeMode ? " 1" : " 0");
return execute(builder.toString());
}
public synchronized String transact(String cmd) {
if (!connect()) {
Slog.e(TAG, “connection failed”);
return “-1”;
}

if (!writeCommand(cmd)) {
/*

• If installd died and restarted in the background (unlikely but
• possible) we’ll fail on the next write (this one). Try to
• reconnect and write the command one more time before giving up.
  */
  Slog.e(TAG, “write command failed? reconnect!”);
  if (!connect() || !writeCommand(cmd)) {
  return “-1”;
  }
  }
  if (LOCAL_DEBUG) {
  Slog.i(TAG, “send: '” + cmd + “'”);
  }

final int replyLength = readReply();
if (replyLength > 0) {
String s = new String(buf, 0, replyLength);
if (LOCAL_DEBUG) {
Slog.i(TAG, “recv: '” + s + “'”);
}
return s;
} else {
if (LOCAL_DEBUG) {
Slog.i(TAG, “fail”);
}
return “-1”;
}
}

public int execute(String cmd) {
String res = transact(cmd);
try {
return Integer.parseInt(res);
} catch (NumberFormatException ex) {
return -1;
}
}
private boolean connect() {
if (mSocket != null) {
return true;
}
Slog.i(TAG, “connecting…”);
try {
mSocket = new LocalSocket();

LocalSocketAddress address = new LocalSocketAddress(“installd”,
LocalSocketAddress.Namespace.RESERVED);

mSocket.connect(address);

mIn = mSocket.getInputStream();
mOut = mSocket.getOutputStream();
} catch (IOException ex) {
disconnect();
return false;
}
return true;
}

由上面的几个方法可以知道,最终dexopt操作是通过socket的方式来跨进程通知守护进程installd,由其去执行dexopt操作。

3.3 commands::dexopt()

最终守护进程installd会调用Commands.c文件(位于/source/framework/native/cmds/installd)的dexopt方法。

int dexopt(const char *apk_path, uid_t uid, bool is_public,
const char *pkgname, const char *instruction_set,
bool vm_safe_mode, bool is_patchoat)
{
struct utimbuf ut;
struct stat input_stat, dex_stat;
char out_path[PKG_PATH_MAX];
char persist_sys_dalvik_vm_lib[PROPERTY_VALUE_MAX];
char *end;
const char *input_file;
char in_odex_path[PKG_PATH_MAX];
int res, input_fd=-1, out_fd=-1;

…
…

pid_t pid;
pid = fork();
if (pid == 0) {
/* child – drop privileges before continuing */
if (setgid(uid) != 0) {
ALOGE(“setgid(%d) failed in installd during dexopt\n”, uid);
exit(64);
}
if (setuid(uid) != 0) {
ALOGE(“setuid(%d) failed in installd during dexopt\n”, uid);
exit(65);
}
// drop capabilities
struct __user_cap_header_struct capheader;
struct __user_cap_data_struct capdata[2];
memset(&capheader, 0, sizeof(capheader));
memset(&capdata, 0, sizeof(capdata));
capheader.version = _LINUX_CAPABILITY_VERSION_3;
if (capset(&capheader, &capdata[0]) < 0) {
ALOGE(“capset failed: %s\n”, strerror(errno));
exit(66);
}
if (set_sched_policy(0, SP_BACKGROUND) < 0) {
ALOGE(“set_sched_policy failed: %s\n”, strerror(errno));
exit(70);
}
if (flock(out_fd, LOCK_EX | LOCK_NB) != 0) {
ALOGE(“flock(%s) failed: %s\n”, out_path, strerror(errno));
exit(67);
}

if (strncmp(persist_sys_dalvik_vm_lib, “libdvm”, 6) == 0) {
run_dexopt(input_fd, out_fd, input_file, out_path);
} else if (strncmp(persist_sys_dalvik_vm_lib, “libart”, 6) == 0) {
if (is_patchoat) {
run_patchoat(input_fd, out_fd, input_file, out_path, pkgname, instruction_set);
} else {
run_dex2oat(input_fd, out_fd, input_file, out_path, pkgname, instruction_set,
vm_safe_mode);
}
} else {
exit(69); /* Unexpected persist.sys.dalvik.vm.lib value /
}
exit(68); / only get here on exec failure */
} else {
res = wait_child(pid);
if (res == 0) {
ALOGV(“DexInv: — END ‘%s’ (success) —\n”, input_file);
} else {
ALOGE(“DexInv: — END ‘%s’ — status=0x%04x, process failed\n”, input_file, res);
goto fail;
}
}

ut.actime = input_stat.st_atime;
ut.modtime = input_stat.st_mtime;
utime(out_path, &ut);

close(out_fd);
close(input_fd);
return 0;

fail:
if (out_fd >= 0) {
close(out_fd);
unlink(out_path);
}
if (input_fd >= 0) {
close(input_fd);
}
return -1;
}

由上面的代码可以发现,installd在做了些操作后,fork出了一个新的进程,根据虚拟机的类型为libdvm或libart分别执行run_dexopt或run_dex2oat(如果为is_patchoat,则是run_patchoat)操作。

4. 更新权限信息

dexopt操作执行完后,installNewPackageLI()方法就会走到updateSettingsLI()来更新设置信息,而更新设置信息主要是权限信息,所以直接来看updatePermissionsLPw();

4.1 updatePermissionsLPw

private void updatePermissionsLPw(String changingPkg,
PackageParser.Package pkgInfo, int flags) {
// Make sure there are no dangling permission trees.
Iterator 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) {
grantPermissionsLPw(pkg, (flags&UPDATE_PERMISSIONS_REPLACE_ALL) != 0,
changingPkg);
}
}
}

if (pkgInfo != null) {
grantPermissionsLPw(pkgInfo, (flags&UPDATE_PERMISSIONS_REPLACE_PKG) != 0, changingPkg);
}
}

private void grantPermissionsLPw(PackageParser.Package pkg, boolean replace,
String packageOfInterest) {
final PackageSetting ps = (PackageSetting) pkg.mExtras;
if (ps == null) {
return;
}
final GrantedPermissions gp = ps.sharedUser != null ? ps.sharedUser : ps;
HashSet origPermissions = gp.grantedPermissions;
boolean changedPermission = false;

if (replace) {
ps.permissionsFixed = false;
if (gp == ps) {
origPermissions = new HashSet(gp.grantedPermissions);
gp.grantedPermissions.clear();
gp.gids = mGlobalGids;
}
}

if (gp.gids == null) {
gp.gids = mGlobalGids;
}

final int N = pkg.requestedPermissions.size();
for (int i=0; i<N; i++) {
final String name = pkg.requestedPermissions.get(i);
final boolean required = pkg.requestedPermissionsRequired.get(i);
final BasePermission bp = mSettings.mPermissions.get(name);
if (DEBUG_INSTALL) {
if (gp != ps) {
Log.i(TAG, "Package " + pkg.packageName + " checking " + name + ": " + bp);
}
}

if (bp == null || bp.packageSetting == null) {
if (packageOfInterest == null || packageOfInterest.equals(pkg.packageName)) {
Slog.w(TAG, "Unknown permission " + name

• " in package " + pkg.packageName);
  }
  continue;
  }

final String perm = bp.name;
boolean allowed;
boolean allowedSig = false;
if ((bp.protectionLevel&PermissionInfo.PROTECTION_FLAG_APPOP) != 0) {
// Keep track of app op permissions.
ArraySet pkgs = mAppOpPermissionPackages.get(bp.name);
if (pkgs == null) {
pkgs = new ArraySet<>();
mAppOpPermissionPackages.put(bp.name, pkgs);
}
pkgs.add(pkg.packageName);
}
final int level = bp.protectionLevel & PermissionInfo.PROTECTION_MASK_BASE;
if (level == PermissionInfo.PROTECTION_NORMAL
|| level == PermissionInfo.PROTECTION_DANGEROUS) {
// We grant a normal or dangerous permission if any of the following
// are true:
// 1) The permission is required
// 2) The permission is optional, but was granted in the past
// 3) The permission is optional, but was requested by an
// app in /system (not /data)
//
// Otherwise, reject the permission.
allowed = (required || origPermissions.contains(perm)
|| (isSystemApp(ps) && !isUpdatedSystemApp(ps)));
} else if (bp.packageSetting == null) {
// This permission is invalid; skip it.
allowed = false;
} else if (level == PermissionInfo.PROTECTION_SIGNATURE) {
allowed = grantSignaturePermission(perm, pkg, bp, origPermissions);
if (allowed) {
allowedSig = true;
}
} else {
allowed = false;
}
if (DEBUG_INSTALL) {
if (gp != ps) {
Log.i(TAG, "Package " + pkg.packageName + " granting " + perm);
}
}
if (allowed) {
if (!isSystemApp(ps) && ps.permissionsFixed) {
// If this is an existing, non-system package, then
// we can’t add any new permissions to it.
if (!allowedSig && !gp.grantedPermissions.contains(perm)) {
// Except… if this is a permission that was added
// to the platform (note: need to only do this when
// updating the platform).
allowed = isNewPlatformPermissionForPackage(perm, pkg);
}
}
if (allowed) {
if (!gp.grantedPermissions.contains(perm)) {
changedPermission = true;
gp.grantedPermissions.add(perm);
gp.gids = appendInts(gp.gids, bp.gids);
} else if (!ps.haveGids) {
gp.gids = appendInts(gp.gids, bp.gids);
}
} else {
if (packageOfInterest == null || packageOfInterest.equals(pkg.packageName)) {
Slog.w(TAG, "Not granting permission " + perm

• " to package " + pkg.packageName
• " because it was previously installed without");
  }
  }
  } else {
  if (gp.grantedPermissions.remove(perm)) {
  changedPermission = true;
  gp.gids = removeInts(gp.gids, bp.gids);
  Slog.i(TAG, "Un-granting permission " + perm
• " from package " + pkg.packageName
• " (protectionLevel=" + bp.protectionLevel
• " flags=0x" + Integer.toHexString(pkg.applicationInfo.flags)
• “)”);
  } else if ((bp.protectionLevel&PermissionInfo.PROTECTION_FLAG_APPOP) == 0) {
  // Don’t print warning for app op permissions, since it is fine for them
  // not to be granted, there is a UI for the user to decide.
  if (packageOfInterest == null || packageOfInterest.equals(pkg.packageName)) {
  Slog.w(TAG, "Not granting permission " + perm
• " to package " + pkg.packageName
• " (protectionLevel=" + bp.protectionLevel
• " flags=0x" + Integer.toHexString(pkg.applicationInfo.flags)
• “)”);
  }
  }
  }
  }

if ((changedPermission || replace) && !ps.permissionsFixed &&
!isSystemApp(ps) || isUpdatedSystemApp(ps)){
// This is the first that we have heard about this package, so the
// permissions we have now selected are fixed until explicitly
// changed.
ps.permissionsFixed = true;
}
ps.haveGids = true;
}

由上面两个方法可以看到,在apk的安装时PMS会将该app的所有权限都记录下来并更新到PMS的mAppOpPermissionPackages成员变量里面,并判定是否授予该app请求的权限。

4.2 完成安装

还记得前面说过的在processPendingInstall方法在执行installPackageLi后会执行以下语句

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);
  } 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!”);