CustomLocale.apk所需要的权限”android.permission.CHANGE_CONFIGURATION”自Android 4.2,4.2.2起系统定义为android:protectionLevel=”signature|system|development”，这就需要在已root的android设置上运行命令：

adb shell pm grant application_package android.permission.CHANGE_CONFIGURATION

下面具体说说pm grant的调用路径。

Pm.java

View Codepublic void run(String[] args) {
        boolean validCommand = false;
        if (args.length < 1) {
            showUsage();
            return;
        }
...
if ("grant".equals(op)) {
            runGrantRevokePermission(true);
            return;
        }
...

private void runGrantRevokePermission(boolean grant) {
        String pkg = nextArg();
        if (pkg == null) {
            System.err.println("Error: no package specified");
            showUsage();
            return;
        }
        String perm = nextArg();
        if (perm == null) {
            System.err.println("Error: no permission specified");
            showUsage();
            return;
        }
        try {
            if (grant) {
                mPm.grantPermission(pkg, perm);
            } else {
                mPm.revokePermission(pkg, perm);
            }
        } catch (RemoteException e) {
            System.err.println(e.toString());
            System.err.println(PM_NOT_RUNNING_ERR);
        } catch (IllegalArgumentException e) {
            System.err.println("Bad argument: " + e.toString());
            showUsage();
        } catch (SecurityException e) {
            System.err.println("Operation not allowed: " + e.toString());
        }
    }

PackageManagerService.java

View Codepublic class PackageManagerService extends IPackageManager.Stub {
...
public void grantPermission(String packageName, String permissionName) {
        mContext.enforceCallingOrSelfPermission(
                android.Manifest.permission.GRANT_REVOKE_PERMISSIONS, null);
        synchronized (mPackages) {
            final PackageParser.Package pkg = mPackages.get(packageName);
            if (pkg == null) {
                throw new IllegalArgumentException("Unknown package: " + packageName);
            }
            final BasePermission bp = mSettings.mPermissions.get(permissionName);
            if (bp == null) {
                throw new IllegalArgumentException("Unknown permission: " + permissionName);
            }

            checkGrantRevokePermissions(pkg, bp);

            final PackageSetting ps = (PackageSetting) pkg.mExtras;
            if (ps == null) {
                return;
            }
            final GrantedPermissions gp = (ps.sharedUser != null) ? ps.sharedUser : ps;
            if (gp.grantedPermissions.add(permissionName)) {
                if (ps.haveGids) {
                    gp.gids = appendInts(gp.gids, bp.gids);
                }
                mSettings.writeLPr();
            }
        }
    }
...

Settings.java

View Codefinal class Settings {
...
private final File mSettingsFilename;
...
Settings(Context context, File dataDir) {
        mContext = context;
        mSystemDir = new File(dataDir, "system");
        mSystemDir.mkdirs();
        FileUtils.setPermissions(mSystemDir.toString(),
                FileUtils.S_IRWXU|FileUtils.S_IRWXG
                |FileUtils.S_IROTH|FileUtils.S_IXOTH,
                -1, -1);
        mSettingsFilename = new File(mSystemDir, "packages.xml");
        mBackupSettingsFilename = new File(mSystemDir, "packages-backup.xml");
        mPackageListFilename = new File(mSystemDir, "packages.list");
        FileUtils.setPermissions(mPackageListFilename, 0660, SYSTEM_UID, PACKAGE_INFO_GID);

        // Deprecated: Needed for migration
        mStoppedPackagesFilename = new File(mSystemDir, "packages-stopped.xml");
        mBackupStoppedPackagesFilename = new File(mSystemDir, "packages-stopped-backup.xml");
    }
...
 void writeLPr() {
        //Debug.startMethodTracing("/data/system/packageprof", 8 * 1024 * 1024);

        // Keep the old settings around until we know the new ones have
        // been successfully written.
        if (mSettingsFilename.exists()) {
            // Presence of backup settings file indicates that we failed
            // to persist settings earlier. So preserve the older
            // backup for future reference since the current settings
            // might have been corrupted.
            if (!mBackupSettingsFilename.exists()) {
                if (!mSettingsFilename.renameTo(mBackupSettingsFilename)) {
                    Log.wtf(PackageManagerService.TAG, "Unable to backup package manager settings, "
                            + " current changes will be lost at reboot");
                    return;
                }
            } else {
                mSettingsFilename.delete();
                Slog.w(PackageManagerService.TAG, "Preserving older settings backup");
            }
        }

        mPastSignatures.clear();

        try {
            FileOutputStream fstr = new FileOutputStream(mSettingsFilename);
            BufferedOutputStream str = new BufferedOutputStream(fstr);

            //XmlSerializer serializer = XmlUtils.serializerInstance();
            XmlSerializer serializer = new FastXmlSerializer();
            serializer.setOutput(str, "utf-8");
            serializer.startDocument(null, true);
            serializer.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);

            serializer.startTag(null, "packages");

            serializer.startTag(null, "last-platform-version");
            serializer.attribute(null, "internal", Integer.toString(mInternalSdkPlatform));
            serializer.attribute(null, "external", Integer.toString(mExternalSdkPlatform));
            serializer.endTag(null, "last-platform-version");

            if (mVerifierDeviceIdentity != null) {
                serializer.startTag(null, "verifier");
                serializer.attribute(null, "device", mVerifierDeviceIdentity.toString());
                serializer.endTag(null, "verifier");
            }

            if (mReadExternalStorageEnforced != null) {
                serializer.startTag(null, TAG_READ_EXTERNAL_STORAGE);
                serializer.attribute(
                        null, ATTR_ENFORCEMENT, mReadExternalStorageEnforced ? "1" : "0");
                serializer.endTag(null, TAG_READ_EXTERNAL_STORAGE);
            }

            serializer.startTag(null, "permission-trees");
            for (BasePermission bp : mPermissionTrees.values()) {
                writePermissionLPr(serializer, bp);
            }
            serializer.endTag(null, "permission-trees");

            serializer.startTag(null, "permissions");
            for (BasePermission bp : mPermissions.values()) {
                writePermissionLPr(serializer, bp);
            }
            serializer.endTag(null, "permissions");

            for (final PackageSetting pkg : mPackages.values()) {
                writePackageLPr(serializer, pkg);
            }

            for (final PackageSetting pkg : mDisabledSysPackages.values()) {
                writeDisabledSysPackageLPr(serializer, pkg);
            }

            for (final SharedUserSetting usr : mSharedUsers.values()) {
                serializer.startTag(null, "shared-user");
                serializer.attribute(null, ATTR_NAME, usr.name);
                serializer.attribute(null, "userId",
                        Integer.toString(usr.userId));
                usr.signatures.writeXml(serializer, "sigs", mPastSignatures);
                serializer.startTag(null, "perms");
                for (String name : usr.grantedPermissions) {
                    serializer.startTag(null, TAG_ITEM);
                    serializer.attribute(null, ATTR_NAME, name);
                    serializer.endTag(null, TAG_ITEM);
                }
                serializer.endTag(null, "perms");
                serializer.endTag(null, "shared-user");
            }

            if (mPackagesToBeCleaned.size() > 0) {
                for (PackageCleanItem item : mPackagesToBeCleaned) {
                    final String userStr = Integer.toString(item.userId);
                    serializer.startTag(null, "cleaning-package");
                    serializer.attribute(null, ATTR_NAME, item.packageName);
                    serializer.attribute(null, ATTR_CODE, item.andCode ? "true" : "false");
                    serializer.attribute(null, ATTR_USER, userStr);
                    serializer.endTag(null, "cleaning-package");
                }
            }
            
            if (mRenamedPackages.size() > 0) {
                for (Map.Entry<String, String> e : mRenamedPackages.entrySet()) {
                    serializer.startTag(null, "renamed-package");
                    serializer.attribute(null, "new", e.getKey());
                    serializer.attribute(null, "old", e.getValue());
                    serializer.endTag(null, "renamed-package");
                }
            }
            
            mKeySetManager.writeKeySetManagerLPr(serializer);

            serializer.endTag(null, "packages");

            serializer.endDocument();

            str.flush();
            FileUtils.sync(fstr);
            str.close();

            // New settings successfully written, old ones are no longer
            // needed.
            mBackupSettingsFilename.delete();
            FileUtils.setPermissions(mSettingsFilename.toString(),
                    FileUtils.S_IRUSR|FileUtils.S_IWUSR
                    |FileUtils.S_IRGRP|FileUtils.S_IWGRP,
                    -1, -1);

            // Write package list file now, use a JournaledFile.
            File tempFile = new File(mPackageListFilename.getAbsolutePath() + ".tmp");
            JournaledFile journal = new JournaledFile(mPackageListFilename, tempFile);

            final File writeTarget = journal.chooseForWrite();
            fstr = new FileOutputStream(writeTarget);
            str = new BufferedOutputStream(fstr);
            try {
                FileUtils.setPermissions(fstr.getFD(), 0660, SYSTEM_UID, PACKAGE_INFO_GID);

                StringBuilder sb = new StringBuilder();
                for (final PackageSetting pkg : mPackages.values()) {
                    if (pkg.pkg == null || pkg.pkg.applicationInfo == null) {
                        Slog.w(TAG, "Skipping " + pkg + " due to missing metadata");
                        continue;
                    }

                    final ApplicationInfo ai = pkg.pkg.applicationInfo;
                    final String dataPath = ai.dataDir;
                    final boolean isDebug = (ai.flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0;
                    final int[] gids = pkg.getGids();

                    // Avoid any application that has a space in its path.
                    if (dataPath.indexOf("") >= 0)
                        continue;

                    // we store on each line the following information for now:
                    //
                    // pkgName - package name
                    // userId - application-specific user id
                    // debugFlag - 0 or 1 if the package is debuggable.
                    // dataPath - path to package's data path
                    // seinfo - seinfo label for the app (assigned at install time)
                    // gids - supplementary gids this app launches with
                    //
                    // NOTE: We prefer not to expose all ApplicationInfo flags for now.
                    //
                    // DO NOT MODIFY THIS FORMAT UNLESS YOU CAN ALSO MODIFY ITS USERS
                    // FROM NATIVE CODE. AT THE MOMENT, LOOK AT THE FOLLOWING SOURCES:
                    // system/core/run-as/run-as.c
                    // system/core/sdcard/sdcard.c
                    //
                    sb.setLength(0);
                    sb.append(ai.packageName);
                    sb.append("");
                    sb.append((int)ai.uid);
                    sb.append(isDebug ? " 1 " : " 0 ");
                    sb.append(dataPath);
                    sb.append("");
                    sb.append(ai.seinfo);
                    sb.append("");
                    if (gids != null && gids.length > 0) {
                        sb.append(gids[0]);
                        for (int i = 1; i < gids.length; i++) {
                            sb.append(",");
                            sb.append(gids[i]);
                        }
                    } else {
                        sb.append("none");
                    }
                    sb.append("\n");
                    str.write(sb.toString().getBytes());
                }
                str.flush();
                FileUtils.sync(fstr);
                str.close();
                journal.commit();
            } catch (Exception e) {
                Log.wtf(TAG, "Failed to write packages.list", e);
                IoUtils.closeQuietly(str);
                journal.rollback();
            }

            writeAllUsersPackageRestrictionsLPr();
            return;

        } catch(XmlPullParserException e) {
            Log.wtf(PackageManagerService.TAG, "Unable to write package manager settings, "
                    + "current changes will be lost at reboot", e);
        } catch(java.io.IOException e) {
            Log.wtf(PackageManagerService.TAG, "Unable to write package manager settings, "
                    + "current changes will be lost at reboot", e);
        }
        // Clean up partially written files
        if (mSettingsFilename.exists()) {
            if (!mSettingsFilename.delete()) {
                Log.wtf(PackageManagerService.TAG, "Failed to clean up mangled file: "
                        + mSettingsFilename);
            }
        }
        //Debug.stopMethodTracing();
    }
...