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search for a valid journal

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there are too many bytes, so we need to find the valid subset,
without stepping past the end!

Bug: 12489602
Change-Id: Ic9d7c804c199740ff50d0864f99632ae68619369
This commit is contained in:
Chris Wren
2014-01-10 14:11:25 -05:00
parent c4fa7a9c4a
commit 65b6a603fa
1 changed files with 37 additions and 23 deletions
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src/com/android/launcher3/LauncherBackupHelper.java
+37 -23
View File
@@ -858,7 +858,7 @@ public class LauncherBackupHelper implements BackupHelper {
* in that case, do a full backup.
*
* @param oldState the read-0only file descriptor pointing to the old journal
* @return a Journal protocol bugffer
* @return a Journal protocol buffer
*/
private Journal readJournal(ParcelFileDescriptor oldState) {
Journal journal = new Journal();
@@ -867,38 +867,50 @@ public class LauncherBackupHelper implements BackupHelper {
}
FileInputStream inStream = new FileInputStream(oldState.getFileDescriptor());
try {
int remaining = inStream.available();
if (DEBUG) Log.d(TAG, "available " + remaining);
if (remaining < MAX_JOURNAL_SIZE) {
byte[] buffer = new byte[remaining];
int availableBytes = inStream.available();
if (DEBUG) Log.d(TAG, "available " + availableBytes);
if (availableBytes < MAX_JOURNAL_SIZE) {
byte[] buffer = new byte[availableBytes];
int bytesRead = 0;
while (remaining > 0) {
boolean valid = false;
while (availableBytes > 0) {
try {
int result = inStream.read(buffer, bytesRead, remaining);
// OMG what are you doing? This is crazy inefficient!
// If we read a byte that is not ours, we will cause trouble: b/12491813
// However, we don't know how many bytes to expect (oops).
// So we have to step through *slowly*, watching for the end.
int result = inStream.read(buffer, bytesRead, 1);
if (result > 0) {
if (DEBUG) Log.d(TAG, "read some bytes: " + result);
remaining -= result;
availableBytes -= result;
bytesRead += result;
if (DEBUG && (bytesRead % 100 == 0)) {
Log.d(TAG, "read some bytes: " + bytesRead);
}
} else {
// stop reading ands see what there is to parse
Log.w(TAG, "read error: " + result);
remaining = 0;
Log.w(TAG, "unexpected end of file while reading journal.");
// stop reading and see what there is to parse
availableBytes = 0;
}
} catch (IOException e) {
Log.w(TAG, "failed to read the journal", e);
Log.e(TAG, "failed to read the journal", e);
buffer = null;
remaining = 0;
availableBytes = 0;
}
// check the buffer to see if we have a valid journal
try {
MessageNano.mergeFrom(journal, readCheckedBytes(buffer, 0, bytesRead));
// if we are here, then we have read a valid, checksum-verified journal
valid = true;
availableBytes = 0;
} catch (InvalidProtocolBufferNanoException e) {
// if we don't have the whole journal yet, mergeFrom will throw. keep going.
journal.clear();
}
}
if (DEBUG) Log.d(TAG, "journal bytes read: " + bytesRead);
if (buffer != null) {
try {
MessageNano.mergeFrom(journal, readCheckedBytes(buffer, 0, bytesRead));
} catch (InvalidProtocolBufferNanoException e) {
Log.d(TAG, "failed to read the journal", e);
journal.clear();
}
if (!valid) {
Log.w(TAG, "failed to read the journal: could not find a valid journal");
}
}
} catch (IOException e) {
@@ -968,7 +980,9 @@ public class LauncherBackupHelper implements BackupHelper {
FileOutputStream outStream = null;
try {
outStream = new FileOutputStream(newState.getFileDescriptor());
outStream.write(writeCheckedBytes(journal));
final byte[] journalBytes = writeCheckedBytes(journal);
if (DEBUG) Log.d(TAG, "writing " + journalBytes.length + " bytes of journal");
outStream.write(journalBytes);
outStream.close();
} catch (IOException e) {
Log.d(TAG, "failed to write backup journal", e);