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Commit cf2ee87f authored by Hai Zhang's avatar Hai Zhang
Browse files

Maintain compatibility by deleting target directory before renaming into it. 

The target shouldn't be a directory, but if it is, it would be
deleted (as long as it's empty). This became some kind of API and we
need to remain compatible with it.

Bug: 151959443
Test: Reboot and ensure ShortcutService can persist its state
Change-Id: I11a80cd4252128b025912b7aab86b113935e549a
Merged-In: I11a80cd4252128b025912b7aab86b113935e549a
parent 25adf3c4

core/java/android/util/AtomicFile.java

+20 −11
Original line number Diff line number Diff line
@@ -116,10 +116,7 @@ public class AtomicFile { 
        mStartTime = startTime;



        if (mLegacyBackupName.exists()) {

            if (!mLegacyBackupName.renameTo(mBaseName)) {

                Log.e(LOG_TAG, "Failed to rename legacy backup file " + mLegacyBackupName

                        + " to base file " + mBaseName);

            }

            rename(mLegacyBackupName, mBaseName);

        }



        try {
@@ -157,9 +154,7 @@ public class AtomicFile { 
        } catch (IOException e) {

            Log.e(LOG_TAG, "Failed to close file output stream", e);

        }

        if (!mNewName.renameTo(mBaseName)) {

            Log.e(LOG_TAG, "Failed to rename new file " + mNewName + " to base file " + mBaseName);

        }

        rename(mNewName, mBaseName);

        if (mCommitTag != null) {

            com.android.internal.logging.EventLogTags.writeCommitSysConfigFile(

                    mCommitTag, SystemClock.uptimeMillis() - mStartTime);
@@ -221,10 +216,7 @@ public class AtomicFile { 
     */

    public FileInputStream openRead() throws FileNotFoundException {

        if (mLegacyBackupName.exists()) {

            if (!mLegacyBackupName.renameTo(mBaseName)) {

                Log.e(LOG_TAG, "Failed to rename legacy backup file " + mLegacyBackupName

                        + " to base file " + mBaseName);

            }

            rename(mLegacyBackupName, mBaseName);

        }



        // Don't delete mNewName here - it was okay to call openRead() between startWrite() and
@@ -301,4 +293,21 @@ public class AtomicFile { 
            IoUtils.closeQuietly(out);

        }

    }



    private static void rename(File source, File target) {

        // We used to delete the target file before rename, but that isn't atomic, and the rename()

        // syscall should atomically replace the target file. However in the case where the target

        // file is a directory, a simple rename() won't work. We need to delete the file in this

        // case because there are callers who erroneously called mBaseName.mkdirs() (instead of

        // mBaseName.getParentFile().mkdirs()) before creating the AtomicFile, and it worked

        // regardless, so this deletion became some kind of API.

        if (target.isDirectory()) {

            if (!target.delete()) {

                Log.e(LOG_TAG, "Failed to delete file which is a directory " + target);

            }

        }

        if (!source.renameTo(target)) {

            Log.e(LOG_TAG, "Failed to rename " + source + " to " + target);

        }

    }

}