Merge "Maintain compatibility by deleting target directory before renaming... (7465a926) · Commits · e / os / android_frameworks_base

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);
		}

		// It was okay to call openRead() between startWrite() and finishWrite() for the first time
		@@ -311,4 +303,21 @@ 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);
		}
		}
		}