Comments on: SFTP/SCP Atomic Copy

By: Pauls ftp storage

Pauls ftp storage — Sun, 29 Aug 2010 13:21:41 +0000

Now we need a patch to patch the patch because this is no longer uploading properly for me on large files!

By: alex

alex — Fri, 12 Feb 2010 11:39:49 +0000

Paul, if I understand correctly with the changes you’ve made now it would work fine on Linux but still fail on WinSCP? Let me know and I’ll update the patch.

By: Paul

Paul — Fri, 12 Feb 2010 09:44:45 +0000

At line 607 in sftp-server.c I added “orginame = NULL”
Thus the code looks like this:
607: xfree(origname);
608: origname = NULL;

The origname isn’t set to NULL on the xfree and thus a command such as “ls” following a file upload would generate an error because it would enter the code block that is only supposed to be used for a file upload.

The atomic upload works fine for the default Linux sftp client but breaks clients such as WinSCP (running in SFTP mode). WinSCP seems to do some sort of operation on the file while it is being uploaded but since it only exists in a temp directory it can’t find the file and spits out errors.

By: Paul

Paul — Thu, 11 Feb 2010 08:48:17 +0000

This patch doesn’t seem to handle file uploads properly.

With small uploads:
The temp directory is used correctly and the file is uploaded and then moved to the destination directory but one ends up with a zero size file in the temp directory and any command following the upload fails and the ssh connection is terminated.

With large uploads:
The temp directory is used correctly and the file is uploaded and then moved to the destination directory but any command following the upload fails and the ssh connection is terminated.

I suspect it’s some file handling issue.