Bug 373003 - wrongly calculated uniqueHash
Summary: wrongly calculated uniqueHash
Status: RESOLVED FIXED
Alias: None
Product: digikam
Classification: Applications
Component: Database-Mysql (show other bugs)
Version: 5.2.0
Platform: openSUSE Linux
: NOR major
Target Milestone: ---
Assignee: Digikam Developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-11-27 20:25 UTC by Kusi
Modified: 2016-11-29 08:29 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed In: 5.4.0
Sentry Crash Report:


Attachments
database.png (133.32 KB, image/png)
2016-11-28 11:28 UTC, Maik Qualmann
Details

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Description Kusi 2016-11-27 20:25:20 UTC
A new uniqueHash algorithm was implemented a few years ago. See https://bugs.kde.org/show_bug.cgi?id=210353. The new algorithm in uniqueHashV2 was only made available for newly created databases. An already existing database was (and is till today) still using the old uniqueHash algorithm. My 10 years old digikam db still uses the old uniqueHash algo. The old algo worked fine till digikam 4.14. During the porting to DK 5, a bug was introduced for the old algo:

In dimgloaded.cpp, the KDE4 command for the old v1 uniqueHash algo
  
   KMD5 md5;
   ...
   hash = md5.hexDigest();

was replaced in the KDE5 porting with ( still uniqueHash v1)

   QCryptographicHash md5(QCryptographicHash::Md5);
   ...
   hash = md5.result();

which is wrong. Instead, it should have been replaced by

   QCryptographicHash md5(QCryptographicHash::Md5);
   ...
   hash = md5.result().toHex();

See the migration document https://api.kde.org/frameworks/kdelibs4support/html/classKMD5.html#a49b31c3e5eb180fa8be8c8f576266221

As a consequence, a database created before 2010 calculates different uniqueHash values in DK5 compared to DK4. Furthermore, UTF8 cannot be used since some of the now calculated uniqueHash values are not valid UTF8 characters, the SQL server erorrs with

  "REPLACE INTO Images  ( album, name, status, category, modificationDate,
  fileSize, uniqueHash )  VALUES (?,?,?,?,?,?,?);"
  Error messages: "QMYSQL3: Unable to execute statement" "Incorrect string
  value: '\\xF1\\x9E\\xA6\\x87' for column 'uniqueHash' at row 1" 1366 2
  Bound values:  (QVariant(int, 118053), QVariant(QString, "P4240656.JPG"),
  QVariant(int, 1), QVariant(int, 1), QVariant(QString,
  "2016-10-30T19:16:42"), QVariant(qlonglong, 6951936), QVariant(QString,
  "m�7�\U0005E987"))

There is uniqueHashVersion in the System table, but the value "2" in DK4 and DK5 return different hash values.

The fix would be easy, just add the missing ".toHex()". However, all images added in DK5 already contain the invalid hash values. They need legacy treatment.

The most clean solution is to get rid of hashValue version 1 and recalculate all hash values in the next DK release

As as sidenote: hashValueV2 is not affected by this bug. This means a db created after 2010 is not affected
Comment 1 caulier.gilles 2016-11-27 20:39:48 UTC
You are right. 

A patch can be easy to make against git/master...

Gilles Caulier
Comment 2 Maik Qualmann 2016-11-27 21:40:01 UTC
Git commit 2b8265ab1c785fae668dec4b468242cc898acc83 by Maik Qualmann.
Committed on 27/11/2016 at 21:39.
Pushed by mqualmann into branch 'master'.

fix wrongly calculated uniqueHash v1
FIXED-IN: 5.4.0

M  +2    -1    NEWS
M  +1    -1    libs/dimg/loaders/dimgloader.cpp
M  +2    -1    utilities/setup/setupdatabase.cpp

https://commits.kde.org/digikam/2b8265ab1c785fae668dec4b468242cc898acc83
Comment 3 Maik Qualmann 2016-11-27 21:44:30 UTC
If you are still at uniqueHash v1 version, see you in setup->database the update button for the uniqueHash v2 version.

Maik
Comment 4 Kusi 2016-11-27 22:47:20 UTC
Maik, where exactly can I update to v2? I don't see any option in the settings of DK5.2

Kusi

PS: thanks for the fast fix!
Comment 5 Maik Qualmann 2016-11-28 11:28:48 UTC
Created attachment 102491 [details]
database.png

See screenshot, if the database has not yet been converted to V2, this entry appears. Otherwise, the entry in the Settings table should be reset external.

SQL Command:
UPDATE digikam.Settings SET value=1 WHERE keyword=uniqueHashVersion;

Maik
Comment 6 Kusi 2016-11-28 23:22:03 UTC
thanks, that solved my problem! Just for reference, before your fix, the "update hash" GUI did not work.

For me, the issue is solved, but I'm sure there are thousands of installations out there with invalid uniqueHash values. I strongly recommend to force a uniqueHash update to v2 in DK 5.4.

Furthermore, most of the SQL errors are not sent to the GUI, they are only visible on the command line. The user just don't see images or other weird behavior and has no clue why. It would be really helpful to be more strict and let the user know in case of errors.
Comment 7 Barbara Scheffner 2016-11-29 08:29:04 UTC
>Furthermore, most of the SQL errors are not sent to the GUI, they are only visible on the command line. The user just don't see images or other weird behavior and has no clue why. It would be really helpful to be more strict and let the user know in case of errors.< (Kusi)

As one of the most silly users (don't even know what a unique hash algorithm is) I can only support this as a matter of principle.