Write staged sessions to /data/staging.

If a session is marked as isStaged, write the package files directly on
a directory named /data/staging/session_${SESSION_ID}, instead of the
/data/app temporary directory. This allows us to set different SELinux
policy (e.g. allowing apexd to read that directory), and to persist the
data across reboots without altering the existing code.

To ensure we cover existing workflows, in this CL we try as much as
possible to re-use existing code to create staging directories and wire
data into them.

Bug: 118865310
Test: Verified that adb install --staged file.apk successfully creates a
/data/staging/session_SESSION_ID/base.apk file. If --apex is passed, the
file is named base.apex.
Change-Id: Iacfd7cfb90b738eeb752fec3e6a4e38ea307259a
diff --git a/core/java/android/os/Environment.java b/core/java/android/os/Environment.java
index 8904ee6..a236300 100644
--- a/core/java/android/os/Environment.java
+++ b/core/java/android/os/Environment.java
@@ -382,6 +382,11 @@
     }
 
     /** {@hide} */
+    public static File getDataStagingDirectory(String volumeUuid) {
+        return new File(getDataDirectory(volumeUuid), "staging");
+    }
+
+    /** {@hide} */
     public static File getDataUserCeDirectory(String volumeUuid) {
         return new File(getDataDirectory(volumeUuid), "user");
     }
diff --git a/services/core/java/com/android/server/pm/PackageInstallerService.java b/services/core/java/com/android/server/pm/PackageInstallerService.java
index 66eae5e..7ca39df 100644
--- a/services/core/java/com/android/server/pm/PackageInstallerService.java
+++ b/services/core/java/com/android/server/pm/PackageInstallerService.java
@@ -209,8 +209,7 @@
         synchronized (mSessions) {
             readSessionsLocked();
 
-            reconcileStagesLocked(StorageManager.UUID_PRIVATE_INTERNAL, false /*isInstant*/);
-            reconcileStagesLocked(StorageManager.UUID_PRIVATE_INTERNAL, true /*isInstant*/);
+            reconcileStagesLocked(StorageManager.UUID_PRIVATE_INTERNAL);
 
             final ArraySet<File> unclaimedIcons = newArraySet(
                     mSessionsDir.listFiles());
@@ -230,8 +229,8 @@
     }
 
     @GuardedBy("mSessions")
-    private void reconcileStagesLocked(String volumeUuid, boolean isEphemeral) {
-        final File stagingDir = buildStagingDir(volumeUuid, isEphemeral);
+    private void reconcileStagesLocked(String volumeUuid) {
+        final File stagingDir = getTmpSessionDir(volumeUuid);
         final ArraySet<File> unclaimedStages = newArraySet(
                 stagingDir.listFiles(sStageFilter));
 
@@ -252,7 +251,7 @@
 
     public void onPrivateVolumeMounted(String volumeUuid) {
         synchronized (mSessions) {
-            reconcileStagesLocked(volumeUuid, false /*isInstant*/);
+            reconcileStagesLocked(volumeUuid);
         }
     }
 
@@ -269,9 +268,9 @@
             try {
                 final int sessionId = allocateSessionIdLocked();
                 mLegacySessions.put(sessionId, true);
-                final File stageDir = buildStageDir(volumeUuid, sessionId, isEphemeral);
-                prepareStageDir(stageDir);
-                return stageDir;
+                final File sessionStageDir = buildTmpSessionDir(sessionId, volumeUuid);
+                prepareStageDir(sessionStageDir);
+                return sessionStageDir;
             } catch (IllegalStateException e) {
                 throw new IOException(e);
             }
@@ -526,9 +525,7 @@
         String stageCid = null;
         if (!params.isMultiPackage) {
             if ((params.installFlags & PackageManager.INSTALL_INTERNAL) != 0) {
-                final boolean isInstant =
-                        (params.installFlags & PackageManager.INSTALL_INSTANT_APP) != 0;
-                stageDir = buildStageDir(params.volumeUuid, sessionId, isInstant);
+                stageDir = buildSessionDir(sessionId, params);
             } else {
                 stageCid = buildExternalStageCid(sessionId);
             }
@@ -634,13 +631,21 @@
         throw new IllegalStateException("Failed to allocate session ID");
     }
 
-    private File buildStagingDir(String volumeUuid, boolean isEphemeral) {
+    private File getTmpSessionDir(String volumeUuid) {
         return Environment.getDataAppDirectory(volumeUuid);
     }
 
-    private File buildStageDir(String volumeUuid, int sessionId, boolean isEphemeral) {
-        final File stagingDir = buildStagingDir(volumeUuid, isEphemeral);
-        return new File(stagingDir, "vmdl" + sessionId + ".tmp");
+    private File buildTmpSessionDir(int sessionId, String volumeUuid) {
+        final File sessionStagingDir = getTmpSessionDir(volumeUuid);
+        return new File(sessionStagingDir, "vmdl" + sessionId + ".tmp");
+    }
+
+    private File buildSessionDir(int sessionId, SessionParams params) {
+        if (params.isStaged) {
+            final File sessionStagingDir = Environment.getDataStagingDirectory(params.volumeUuid);
+            return new File(sessionStagingDir, "session_" + sessionId);
+        }
+        return buildTmpSessionDir(sessionId, params.volumeUuid);
     }
 
     static void prepareStageDir(File stageDir) throws IOException {
diff --git a/services/core/java/com/android/server/pm/PackageInstallerSession.java b/services/core/java/com/android/server/pm/PackageInstallerSession.java
index d4ee61b..11b58fb 100644
--- a/services/core/java/com/android/server/pm/PackageInstallerSession.java
+++ b/services/core/java/com/android/server/pm/PackageInstallerSession.java
@@ -977,18 +977,18 @@
 
         // Read transfers from the original owner stay open, but as the session's data
         // cannot be modified anymore, there is no leak of information.
-        if (!params.isMultiPackage) {
+        // For staged sessions, the validation is performed by StagingManager.
+        if (!params.isMultiPackage && !params.isStaged) {
             final PackageInfo pkgInfo = mPm.getPackageInfo(
                     params.appPackageName, PackageManager.GET_SIGNATURES
                             | PackageManager.MATCH_STATIC_SHARED_LIBRARIES /*flags*/, userId);
 
             resolveStageDirLocked();
 
-            // Verify that stage looks sane with respect to existing application.
-            // This currently only ensures packageName, versionCode, and certificate
-            // consistency.
             try {
                 if ((params.installFlags & PackageManager.INSTALL_APEX) != 0) {
+                    // TODO(b/118865310): Remove this when APEX validation is done via
+                    //                    StagingManager.
                     validateApexInstallLocked(pkgInfo);
                 } else {
                     // Verify that stage looks sane with respect to existing application.
@@ -1061,16 +1061,17 @@
     @GuardedBy("mLock")
     private void commitLocked()
             throws PackageManagerException {
+        if (params.isStaged) {
+            mStagingManager.commitSession(this);
+            destroyInternal();
+            dispatchSessionFinished(PackageManager.INSTALL_SUCCEEDED, "Session staged", null);
+            return;
+        }
         final PackageManagerService.ActiveInstallSession committingSession =
                 makeSessionActiveLocked();
         if (committingSession == null) {
             return;
         }
-        if (isStaged()) {
-            mStagingManager.commitSession(this);
-            dispatchSessionFinished(PackageManager.INSTALL_SUCCEEDED, "Session staged", null);
-            return;
-        }
         if (isMultiPackage()) {
             final int[] childSessionIds = getChildSessionIds();
             List<PackageManagerService.ActiveInstallSession> childSessions =
@@ -1973,7 +1974,11 @@
                 bridge.forceClose();
             }
         }
-        if (stageDir != null) {
+        // For staged sessions, we don't delete the directory where the packages have been copied,
+        // since these packages are supposed to be read on reboot. StagingManager is in charge of
+        // deleting these dirs when the staged session has reached a final state.
+        // TODO(b/118865310): Implement packageDir deletion in StagingManager.
+        if (stageDir != null && !params.isStaged) {
             try {
                 mPm.mInstaller.rmPackageDir(stageDir.getAbsolutePath());
             } catch (InstallerException ignored) {
diff --git a/services/core/java/com/android/server/pm/PackageManagerShellCommand.java b/services/core/java/com/android/server/pm/PackageManagerShellCommand.java
index ac9c6ef..2e9d26a 100644
--- a/services/core/java/com/android/server/pm/PackageManagerShellCommand.java
+++ b/services/core/java/com/android/server/pm/PackageManagerShellCommand.java
@@ -2293,6 +2293,9 @@
                     break;
                 case "--apex":
                     sessionParams.installFlags |= PackageManager.INSTALL_APEX;
+                    // TODO(b/118865310): APEX packages should always imply
+                    //                    sessionParams.isStaged(). Enforce this when the staged
+                    //                    install workflow is complete.
                     break;
                 case "--multi-package":
                     sessionParams.setMultiPackage();
@@ -2588,7 +2591,7 @@
         try {
             session = new PackageInstaller.Session(
                     mInterface.getPackageInstaller().openSession(sessionId));
-            if (!session.isMultiPackage()) {
+            if (!session.isMultiPackage() && !session.isStaged()) {
                 // Sanity check that all .dm files match an apk.
                 // (The installer does not support standalone .dm files and will not process them.)
                 try {