Install system app in greatest priority partition

On Pixel 2 devices, /product is a symlink to /system/product. The
product partition has a higher partition precedence than the system
partition so the app should be installed as a system app on the product
partition.

This change also unifies methods for checking whether a file is within
a partition so we will paths will always be canonicalized before the
check.

Bug: 152522330
Test: update system app in system/product/privapp, uninstall updates,
      verify that the app was scanned as privileged
Change-Id: I646a5f293b977a78daa2102b73f1d3122f774a2a

6 files changed, 66 insertions, 51 deletions

diff --git a/core/java/android/content/pm/PackagePartitions.java b/core/java/android/content/pm/PackagePartitions.java
index 9b8396e340ea..653b9ec9e8f2 100644
--- a/core/java/android/content/pm/PackagePartitions.java
+++ b/core/java/android/content/pm/PackagePartitions.java
@@ -93,15 +93,23 @@ public class PackagePartitions {
         return out;
     }
 
+    private static File canonicalize(File path) {
+        try {
+            return path.getCanonicalFile();
+        } catch (IOException e) {
+            return path;
+        }
+    }
+
     /** Represents a partition that contains application packages. */
     @VisibleForTesting(visibility = VisibleForTesting.Visibility.PRIVATE)
     public static class SystemPartition {
-        @NonNull
-        public final File folder;
-
         @PartitionType
         public final int type;
 
+        @NonNull
+        private final DeferredCanonicalFile mFolder;
+
         @Nullable
         private final DeferredCanonicalFile mAppFolder;
 
@@ -113,18 +121,18 @@ public class PackagePartitions {
 
         private SystemPartition(@NonNull File folder, @PartitionType int type,
                 boolean containsPrivApp, boolean containsOverlay) {
-            this.folder = folder;
             this.type = type;
+            this.mFolder = new DeferredCanonicalFile(folder);
             this.mAppFolder = new DeferredCanonicalFile(folder, "app");
-            this.mPrivAppFolder = containsPrivApp ?
-                    new DeferredCanonicalFile(folder, "priv-app") : null;
-            this.mOverlayFolder = containsOverlay ?
-                    new DeferredCanonicalFile(folder, "overlay") : null;
+            this.mPrivAppFolder = containsPrivApp ? new DeferredCanonicalFile(folder, "priv-app")
+                    : null;
+            this.mOverlayFolder = containsOverlay ? new DeferredCanonicalFile(folder, "overlay")
+                    : null;
         }
 
         public SystemPartition(@NonNull SystemPartition original) {
-            this.folder = original.folder;
             this.type = original.type;
+            this.mFolder = new DeferredCanonicalFile(original.mFolder.getFile());
             this.mAppFolder = original.mAppFolder;
             this.mPrivAppFolder = original.mPrivAppFolder;
             this.mOverlayFolder = original.mOverlayFolder;
@@ -139,6 +147,12 @@ public class PackagePartitions {
                     partition.mOverlayFolder != null);
         }
 
+        /** Returns the canonical folder of the partition. */
+        @NonNull
+        public File getFolder() {
+            return mFolder.getFile();
+        }
+
         /** Returns the canonical app folder of the partition. */
         @Nullable
         public File getAppFolder() {
@@ -157,30 +171,29 @@ public class PackagePartitions {
             return mOverlayFolder == null ? null : mOverlayFolder.getFile();
         }
 
+        /** Returns whether the partition contains the specified file. */
+        public boolean containsPath(@NonNull String path) {
+            return containsFile(new File(path));
+        }
+
+        /** Returns whether the partition contains the specified file. */
+        public boolean containsFile(@NonNull File file) {
+            return FileUtils.contains(mFolder.getFile(), canonicalize(file));
+        }
+
         /** Returns whether the partition contains the specified file in its priv-app folder. */
         public boolean containsPrivApp(@NonNull File scanFile) {
-            return FileUtils.contains(mPrivAppFolder.getFile(), scanFile);
+            return FileUtils.contains(mPrivAppFolder.getFile(), canonicalize(scanFile));
         }
 
         /** Returns whether the partition contains the specified file in its app folder. */
         public boolean containsApp(@NonNull File scanFile) {
-            return FileUtils.contains(mAppFolder.getFile(), scanFile);
+            return FileUtils.contains(mAppFolder.getFile(), canonicalize(scanFile));
         }
 
         /** Returns whether the partition contains the specified file in its overlay folder. */
         public boolean containsOverlay(@NonNull File scanFile) {
-            return FileUtils.contains(mOverlayFolder.getFile(), scanFile);
-        }
-
-        /** Returns whether the partition contains the specified file. */
-        public boolean containsPath(@NonNull String path) {
-            return path.startsWith(folder.getPath() + "/");
-        }
-
-        /** Returns whether the partition contains the specified file in its priv-app folder. */
-        public boolean containsPrivPath(@NonNull String path) {
-            return mPrivAppFolder != null
-                    && path.startsWith(mPrivAppFolder.getFile().getPath() + "/");
+            return FileUtils.contains(mOverlayFolder.getFile(), canonicalize(scanFile));
         }
     }
 
@@ -190,22 +203,24 @@ public class PackagePartitions {
      * have the correct selinux policies.
      */
     private static class DeferredCanonicalFile {
-        private boolean mIsCanonical;
+        private boolean mIsCanonical = false;
+
+        @NonNull
         private File mFile;
-        private DeferredCanonicalFile(File dir, String fileName) {
+
+        private DeferredCanonicalFile(@NonNull File dir) {
+            mFile = dir;
+        }
+
+        private DeferredCanonicalFile(@NonNull File dir, @NonNull String fileName) {
             mFile = new File(dir, fileName);
-            mIsCanonical = false;
         }
 
+        @NonNull
         private File getFile() {
-            if (mIsCanonical) {
-                return mFile;
-            }
-            mIsCanonical = true;
-            try {
-                mFile = mFile.getCanonicalFile();
-            } catch (IOException ignore) {
-                // failed to look up canonical path, continue with original one
+            if (!mIsCanonical) {
+                mFile = canonicalize(mFile);
+                mIsCanonical = true;
             }
             return mFile;
         }
diff --git a/core/java/com/android/internal/content/om/OverlayConfig.java b/core/java/com/android/internal/content/om/OverlayConfig.java
index fbef027ac37f..3b5cf487c8da 100644
--- a/core/java/com/android/internal/content/om/OverlayConfig.java
+++ b/core/java/com/android/internal/content/om/OverlayConfig.java
@@ -110,7 +110,9 @@ public class OverlayConfig {
         } else {
             // Rebase the system partitions and settings file on the specified root directory.
             partitions = new ArrayList<>(PackagePartitions.getOrderedPartitions(
-                    p -> new OverlayPartition(new File(rootDirectory, p.folder.getPath()), p)));
+                    p -> new OverlayPartition(
+                            new File(rootDirectory, p.getFolder().getPath()),
+                            p)));
         }
 
         boolean foundConfigFile = false;
@@ -143,7 +145,7 @@ public class OverlayConfig {
                 // Filter out overlays not present in the partition.
                 partitionOverlayInfos = new ArrayList<>(packageManagerOverlayInfos);
                 for (int j = partitionOverlayInfos.size() - 1; j >= 0; j--) {
-                    if (!partition.containsPath(partitionOverlayInfos.get(j).path.getPath())) {
+                    if (!partition.containsFile(partitionOverlayInfos.get(j).path)) {
                         partitionOverlayInfos.remove(j);
                     }
                 }
diff --git a/core/java/com/android/internal/content/om/OverlayConfigParser.java b/core/java/com/android/internal/content/om/OverlayConfigParser.java
index 139607ff7196..a86e5950c2f6 100644
--- a/core/java/com/android/internal/content/om/OverlayConfigParser.java
+++ b/core/java/com/android/internal/content/om/OverlayConfigParser.java
@@ -27,8 +27,8 @@ import android.util.ArraySet;
 import android.util.Log;
 import android.util.Xml;
 
-import com.android.internal.util.XmlUtils;
 import com.android.internal.content.om.OverlayScanner.ParsedOverlayInfo;
+import com.android.internal.util.XmlUtils;
 
 import libcore.io.IoUtils;
 
@@ -154,7 +154,7 @@ final class OverlayConfigParser {
                     return POLICY_PRODUCT;
                 default:
                     throw new IllegalStateException("Unable to determine policy for "
-                            + partition.folder);
+                            + partition.getFolder());
             }
         }
     }
diff --git a/services/core/java/com/android/server/pm/PackageManagerService.java b/services/core/java/com/android/server/pm/PackageManagerService.java
index aa7a1ad2b47a..fd861b56b729 100644
--- a/services/core/java/com/android/server/pm/PackageManagerService.java
+++ b/services/core/java/com/android/server/pm/PackageManagerService.java
@@ -2711,13 +2711,13 @@ public class PackageManagerService extends IPackageManager.Stub
                     return SCAN_AS_SYSTEM_EXT;
                 default:
                     throw new IllegalStateException("Unable to determine scan flag for "
-                            + partition.folder);
+                            + partition.getFolder());
             }
         }
 
         @Override
         public String toString() {
-            return folder.getAbsolutePath() + ":" + scanFlag;
+            return getFolder().getAbsolutePath() + ":" + scanFlag;
         }
     }
 
@@ -3283,7 +3283,7 @@ public class PackageManagerService extends IPackageManager.Stub
 
                         @ParseFlags int reparseFlags = 0;
                         @ScanFlags int rescanFlags = 0;
-                        for (int i1 = 0, size = mDirsToScanAsSystem.size(); i1 < size; i1++) {
+                        for (int i1 = mDirsToScanAsSystem.size() - 1; i1 >= 0; i1--) {
                             final ScanPartition partition = mDirsToScanAsSystem.get(i1);
                             if (partition.containsPrivApp(scanFile)) {
                                 reparseFlags = systemParseFlags;
@@ -18681,7 +18681,7 @@ public class PackageManagerService extends IPackageManager.Stub
         for (int i = 0, size = SYSTEM_PARTITIONS.size(); i < size; i++) {
             ScanPartition sp = SYSTEM_PARTITIONS.get(i);
             if (apexInfo.preInstalledApexPath.getAbsolutePath().startsWith(
-                    sp.folder.getAbsolutePath())) {
+                    sp.getFolder().getAbsolutePath())) {
                 return new ScanPartition(apexInfo.apexDirectory, sp, SCAN_AS_APK_IN_APEX);
             }
         }
@@ -18777,23 +18777,23 @@ public class PackageManagerService extends IPackageManager.Stub
             @Nullable int[] allUserHandles, @Nullable int[] origUserHandles,
             @Nullable PermissionsState origPermissionState, boolean writeSettings)
                     throws PackageManagerException {
+        final File codePath = new File(codePathString);
         @ParseFlags int parseFlags =
                 mDefParseFlags
                 | PackageParser.PARSE_MUST_BE_APK
                 | PackageParser.PARSE_IS_SYSTEM_DIR;
         @ScanFlags int scanFlags = SCAN_AS_SYSTEM;
-        for (int i = 0, size = mDirsToScanAsSystem.size(); i < size; i++) {
+        for (int i = mDirsToScanAsSystem.size() - 1; i >= 0; i--) {
             ScanPartition partition = mDirsToScanAsSystem.get(i);
-            if (partition.containsPath(codePathString)) {
+            if (partition.containsFile(codePath)) {
                 scanFlags |= partition.scanFlag;
-                if (partition.containsPrivPath(codePathString)) {
+                if (partition.containsPrivApp(codePath)) {
                     scanFlags |= SCAN_AS_PRIVILEGED;
                 }
                 break;
             }
         }
 
-        final File codePath = new File(codePathString);
         final AndroidPackage pkg =
                 scanPackageTracedLI(codePath, parseFlags, scanFlags, 0 /*currentTime*/, null);
 
diff --git a/services/core/java/com/android/server/pm/Settings.java b/services/core/java/com/android/server/pm/Settings.java
index a5b1bf98cdb7..936ba7f3b097 100644
--- a/services/core/java/com/android/server/pm/Settings.java
+++ b/services/core/java/com/android/server/pm/Settings.java
@@ -3235,7 +3235,7 @@ public final class Settings {
             PackageManagerService.ScanPartition partition =
                     PackageManagerService.SYSTEM_PARTITIONS.get(index);
 
-            File preferredDir = new File(partition.folder, "etc/preferred-apps");
+            File preferredDir = new File(partition.getFolder(), "etc/preferred-apps");
             if (!preferredDir.exists() || !preferredDir.isDirectory()) {
                 continue;
             }
diff --git a/services/tests/servicestests/src/com/android/server/pm/PackageManagerServiceTest.java b/services/tests/servicestests/src/com/android/server/pm/PackageManagerServiceTest.java
index 37c106094954..c4e25b53d5d5 100644
--- a/services/tests/servicestests/src/com/android/server/pm/PackageManagerServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/pm/PackageManagerServiceTest.java
@@ -122,10 +122,8 @@ public class PackageManagerServiceTest {
             final PackageManagerService.ScanPartition scanPartition =
                     PackageManagerService.SYSTEM_PARTITIONS.get(i);
             for (int j = 0; j < appdir.length; j++) {
-                String canonical = new File("/" + partitions[i]).getCanonicalPath();
-                String path = String.format("%s/%s/A.apk", canonical, appdir[j]);
-
-                Assert.assertEquals(j == 1 && i != 3, scanPartition.containsPrivPath(path));
+                File path = new File(String.format("%s/%s/A.apk", partitions[i], appdir[j]));
+                Assert.assertEquals(j == 1 && i != 3, scanPartition.containsPrivApp(path));
 
                 final int scanFlag = scanPartition.scanFlag;
                 Assert.assertEquals(i == 1, scanFlag == PackageManagerService.SCAN_AS_VENDOR);