[GNC] cannot write back to Windows share

[Mark Bourne]

Louise wrote:
> I think this might be "programmers" question rather than a GnuCash 
> question.
> 
> I have an existing Windows 10 system, but I am trialing Linux mint 22.3 
> in a VMWare virtual machine. I am looking at droppingW10 when I'm happy 
> with Linux. So far so good but I have an issue with GnuCash.
> 
> My data is still on the Windows drive. I have set up an auto mount for 
> launch. I can access the data on the windows share, but GnuCash wont let 
> me save changes back to the windows share.
> 
> This is the message:

[Attached image shows "GnuCash could not write to 
/media/windows/data/Documents/Finances/Accounts and Budgets/GnuCash/2026 
Accounts.gnucash. That database may be on a read-only file system, you 
may not have write permission for the directory or your anti-virus 
software is preventing this action."]

Can you create new files in the shared folder?

I don't use GnuCash in a VM but, with other applications running on an 
Ubuntu Linux guest under VirtualBox on a Windows host, I have found that 
files can be created in a shared folder on the Linux guest but then 
can't be modified, giving a message implying the file is read-only. 
Although my experience is with VirtualBox, it could be that something 
similar can happen with VMware (presumably Workstation?).  I don't know 
what the cause of the problem is; perhaps some process on the Windows 
host (maybe antivirus or other security software) holds a handle on the 
file so that it can't be opened for writing.

> I set permissions to 777, But when I look at the accounts file, I have 
> read/write, my group only has read-only.
> 
> What should the permissions be, and what would be the best way to set 
> them properly.

The underlying filesystem mounted at /media/windows/ (or maybe 
/media/windows/data/ is the mount point) in the VM is still a Windows 
filesystem, where permissions work very differently than on Linux.  You 
probably can't reliably change permissions from the Linux guest.

I'm not sure offhand how shared folders work with VMware.  With 
VirtualBox, a "Guest Additions" package needs to be installed in the 
guest.  Folders shared from the host are then mounted under /media/ as 
being owned by root but with a "vboxsf" group having read/write 
permissions (and no access for other users).  The user account in the 
guest needs to be added to that vboxsf group to be able to access the 
folder at all.

Still on VirtualBox, there's an option when setting up a shared folder 
in the VM settings to specify whether the folder is read-only or 
read/write within the guest.  Is there a similar option in VMware?  Is 
it set to read/write?  On VirtualBox, the directory in the guest still 
appears to have write permission for the vboxsf group, but attempting to 
write to it fails with a "read-only file system" error.  Perhaps VMware 
more accurately reflects that via the group write bit if the share is 
configured to be read-only, so check in VMware that the share is 
configured to be writeable.

Do the files/directories appear as owned by the user you're logged in as 
within the guest, and does that user have write permissions?  If so, you 
should be fine as far as the emulated Linux permissions go even if the 
group doesn't have write permission.  However, the filesystem still 
might not actually allow writes (which is what seems to happen in my 
case with VirtualBox).

Not sure how much any of that will help, given I have little experience 
of VMware Workstation, but perhaps it will give some ideas of things to 
look for...

-- 
Mark.