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Merge "Maintain compatibility by deleting target directory before renaming into it." into rvc-dev

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This commit is contained in:
TreeHugger Robot
2020-05-20 23:20:42 +00:00
committed by Android (Google) Code Review
parent 129b3ffbbb cf2ee87fd4
commit 5c77ec2e12
1 changed files with 20 additions and 11 deletions
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31
core/java/android/util/AtomicFile.java
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@@ -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);
}
}
}