Greetings. Got the following situation:
OS WIndows 7 (Embedded edition)
Filesystem - NTFS

What i want - after downloading torrent move files to another drive (or drive pool), make symlink and start seeding. There is no problem when file-allocation is none or prealloc.

When i set file-allocation=falloc - files are created, explorer shows size as in torrent, but download stucks for some time ~ time of file allocation. And then it's ok with seeding over symlink.

When i set file-allocation=trunc - files are created, size is normal and download starts immediately. But after moving and symlinking i got errors:

About torrent states - i move files after i call pause on torrent. And then i call unpause.
What's interesting - most often it occurs with multi-file torrents.

With additional log i got this

Probably, this is limitation of NTFS + sparse files, or some sort.
For me, sparse files on NTFS (or Windows API in general) is still rather black magic.
The relevant part of the code is
https://github.com/tatsuhiro-t/aria2/blob/9bce4eb925794528b21b4cdb0f7777ac24ffd7c2/src/AbstractDiskWriter.cc#L473

I think the problem is with the control file. When i pause finished torrent - control file still exists. And probably when symlink is created aria2 decided that torrent is not compled and is trying to allocate files again.

I've read documentation, but i don't understand when control file is deleted?

A control file is removed when download was finished.
But if --force-save is used, they are not removed.

I've tested multiple combination of options. In all cases when torrent is multi-file, after i unpause torrent aria2 is trying to allocate files.

Single-file torrent has no problems with allocate, it just starts seeding after unpause.
The only way i got it working with multi-file - set file-allocation=none.

This error Making file sparse failed or pending: Incorrect function. occurs only when symlink is on another drive. When it is symlinking on the same drive - it stucks on FileAlloc 100%.

We use same code to allocate space for both single and multi file torrent.
BTW, do you symlink to each file, or just a top level directory?

Only files inside folder and any subfolder. So folder structure stays as is.

So if you have 100 files in multi torrent, do you create 100 symlinks?

Yes :) But in most cases I had 3-5 files in the torrent.

c2157e6 fixes the bug that file allocation gets stuck at 100%.
I could not reproduce 'Incorrect function.' error since I don't have necessary environment.

I've build aria2 with your fix. After testing all day i got following:

1. The problem is not with aria2, it with pooling software 'DriveBender'. When i symlink to another drive (not in pool) - it's ok.
2. Your fix is working great - no problem with symlink to same drive
3. When i enable check-integrity - aria2 shows 'checksum' in console. And it's ok. Right after checksum it writes error. So the file is determined normal
4. You added log in MultiFileAllocationIterator.cc. It shows 'current size=0'. I think file size detection is wrong :(

Here is logs from single-file torrent

logs from multi-file torrent

But finaly torrents starts seeding. So the only problem is - why checksum is OK, but aria starts file allocation?

With 432675e, aria2 now correctly get file size for target file of symlink.

Great! It's working! No errors and torrents are seeding! Many thx!

OK, let's close the issue.