Error parsing WhatsApp DB (Comparison method violates its general contract)

[wladimirleite]

Another user reported the following error (it happens both with 4.1.x and master). Analysing the database, the issue is caused by the way messages are sorted. It may fail when a very specific combination of records (with zeroes or null values in the columns used) is present, which is the case of the triggering database. I will submit a fix shortly.

2024-10-15 09:32:48 [ERROR] [parsers.whatsapp.WhatsAppParser]           Error parsing WhatsApp: Item: XXX/msgstore.db type: sqlite size: 61648896
org.apache.tika.exception.TikaException: WAExtractorException Exception
    at iped.parsers.whatsapp.WhatsAppParser.parseWhatsappMessages(WhatsAppParser.java:399) ~[iped-parsers-impl-4.2-snapshot.jar:?]
    at iped.parsers.whatsapp.WhatsAppParser.parse(WhatsAppParser.java:259) [iped-parsers-impl-4.2-snapshot.jar:?]
    at org.apache.tika.parser.CompositeParser.parse(CompositeParser.java:298) [tika-core-2.4.0-p1.jar:2.4.0]
    at iped.parsers.standard.StandardParser.parse(StandardParser.java:245) [iped-parsers-impl-4.2-snapshot.jar:?]
    at iped.engine.io.ParsingReader$BackgroundParsing.run(ParsingReader.java:247) [iped-engine-4.2-snapshot.jar:?]
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:?]
    at java.util.concurrent.FutureTask.run(Unknown Source) [?:?]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:?]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:?]
    at java.lang.Thread.run(Unknown Source) [?:?]
Caused by: java.lang.IllegalArgumentException: Comparison method violates its general contract!
    at java.util.ComparableTimSort.mergeHi(Unknown Source) ~[?:?]
    at java.util.ComparableTimSort.mergeAt(Unknown Source) ~[?:?]
    at java.util.ComparableTimSort.mergeForceCollapse(Unknown Source) ~[?:?]
    at java.util.ComparableTimSort.sort(Unknown Source) ~[?:?]
    at java.util.Arrays.sort(Unknown Source) ~[?:?]
    at java.util.Arrays.sort(Unknown Source) ~[?:?]
    at java.util.ArrayList.sort(Unknown Source) ~[?:?]
    at java.util.Collections.sort(Unknown Source) ~[?:?]
    at iped.parsers.whatsapp.ExtractorAndroidNew.extractChatList(ExtractorAndroidNew.java:150) ~[iped-parsers-impl-4.2-snapshot.jar:?]
    at iped.parsers.whatsapp.Extractor.getChatList(Extractor.java:34) ~[iped-parsers-impl-4.2-snapshot.jar:?]
    at iped.parsers.whatsapp.WhatsAppParser.parseWhatsappMessages(WhatsAppParser.java:391) ~[iped-parsers-impl-4.2-snapshot.jar:?]
    ... 9 more

[wladimirleite]

Out of curiosity, the problem is caused when we try to sort items and some of them don't have a "linear" order (A > B, B > C and C > A). The comparator used by the WhatsAppParser is something like:

public int compareTo(Message o) {
    if (a != 0 && o.a != 0) {
        int cmp = Integer.compare(a, o.a);
        if (cmp != 0) return cmp;
    }
    if (b != 0 && o.b != 0) {
        int cmp = Integer.compare(b, o.b);
        if (cmp != 0) return cmp;
    }
    return Integer.compare(c, o.c);
}

If we have items like X = {a=0, b=2, c=1}, Y = {a=2, b=1, c=0}, Z = {a=1, b=0, c=2}, then: X > Y, Y > Z and Z > X, which will cause an exception if we try to sort them (in fact, there must be at least 32 items, so the merge function is used).