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Commit 00001111 authored by Billy Lau's avatar Billy Lau
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BinaryTransparencyService: Fix getOriginalApexPreinstalledLocation 

The existing `getOriginalApexPreinstalledLocation` method makes use
of heuristics to determine the filename of originally APEXs
preinstalled on the /system/apex directory.

This change fixes the method to perform prefix comparison instead
of relying on previous heuristics, and thus making this method
more robust overall against package name mismatch, and provides
clear error signals now.

Bug: 259349011
Test: atest BinaryTransparencyServiceTest
Change-Id: Iff6d1041c71e10522f744b9569f5827bb14ed238
parent 4ae8fc3e

services/core/java/com/android/server/BinaryTransparencyService.java

+16 −8
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ import java.util.Map; 
import java.util.Set;

import java.util.concurrent.Executors;

import java.util.stream.Collectors;

import java.util.stream.Stream;



/**

 * @hide
@@ -104,6 +105,9 @@ public class BinaryTransparencyService extends SystemService { 
    @VisibleForTesting

    static final String BUNDLE_CONTENT_DIGEST = "content-digest";



    static final String APEX_PRELOAD_LOCATION = "/system/apex/";

    static final String APEX_PRELOAD_LOCATION_ERROR = "could-not-be-determined";



    // used for indicating any type of error during MBA measurement

    static final int MBA_STATUS_ERROR = 0;

    // used for indicating factory condition preloads
@@ -1110,18 +1114,22 @@ public class BinaryTransparencyService extends SystemService { 
        }

    }



    // TODO(b/259349011): Need to be more robust against package name mismatch in the filename

    @NonNull

    private String getOriginalApexPreinstalledLocation(String packageName,

                                                   String currentInstalledLocation) {

        if (currentInstalledLocation.contains("/decompressed/")) {

            String resultPath = "system/apex" + packageName + ".capex";

            File f = new File(resultPath);

            if (f.exists()) {

                return resultPath;

        // get a listing of all apex files in /system/apex/

        Set<String> originalApexs = Stream.of(new File(APEX_PRELOAD_LOCATION).listFiles())

                                        .filter(f -> !f.isDirectory())

                                        .map(File::getName)

                                        .collect(Collectors.toSet());



        for (String originalApex : originalApexs) {

            if (originalApex.startsWith(packageName)) {

                return APEX_PRELOAD_LOCATION + originalApex;

            }

            return "/system/apex/" + packageName + ".next.capex";

        }

        return "/system/apex" + packageName + "apex";



        return APEX_PRELOAD_LOCATION_ERROR;

    }



    /**