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[Big Muscle <bigmuscle@xxxxxxxxxx>]

I found another possible source of file corruption. When file is being
transferred with ZLIB compression, it can happen that decompression
error or ""Garbage data after end of stream" exceptions occur after the
last bytes of segment has been transferred. These exceptions will be
caught in DownloadManager::on(Data)'s handler and therefore endData
won't be executed. But the whole segment can be marked as downloaded and
file will be seen as finished in queue. It can cause file corruption and
crash when removing such file from queue.

-- 
Possible file corruption
https://bugs.launchpad.net/bugs/550300
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Status in DC++: Confirmed

Bug description:
This bug happens due to following source code:

FilteredFile.h, line 141: flushed = true;

Flushed flag is set to true although file is not flushed at this time. It causes that flushing in DownloadManager::endData() fails, because it thinks that file has already been flushed. If some system error (crash, hang etc.) occurs, file content will be lost, because it hasn't been flushed to disk.

Another problem with same source code is there. When user's HashData is not accessible (e.g. no access to file, file is corrupted etc.) and client can't get tree from such user, it uses only simple kind of verification - by TTH root. It's ok, but because DownloadManager/FilteredFile thinks that the file has already been flushed, it doesn't verify TTH root on file finish at all. So even though downloaded file's TTH root is different from original TTH root (i.e. file is corrupted), the file is normally finished and DC++ doesn't say any error (but it should say "TTH inconsistency" or something).

Possible solution for both problem would be to remove that "flushed = true" line and reset download position when flush fails on download finish (DownloadManager.cpp, line 328), so such segment wouldn't be marked as downloaded.