Re: BDiskDeviceParameterEditor, BDiskScannerParameterEditor, and PartitioningDialog confusion

On Thu, 2 Aug 2007, James Urquhart wrote:

> I recently fixed up the DriveSetup preferences app a bit ( patch located on 
> the trac at http://dev.haiku-os.org/ticket/1347  ), but came a bit stuck when 
> i got to shelling out the Partition & Initialisation code.
>
> Looking through the Haiku storage kit, i first noticed that BPartition 
> exposes code which allows me to obtain a BDiskDeviceParameterEditor, via any 
> of four functions:
>
> status_t BPartition::GetParameterEditor(BDiskDeviceParameterEditor **editor)
> status_t BPartition::GetContentParameterEditor(BDiskDeviceParameterEditor 
> **editor)
> status_t BPartition::GetInitializationParameterEditor(const char *system, 
> BDiskDeviceParameterEditor **editor) const
> status_t BPartition::GetChildCreationParameterEditor(const char *system, 
> BDiskDeviceParameterEditor **editor) const
>
> Sad to say, i am left clueless as to which one of these functions i should 
> use for which circumstance - i thought the original DriveSetup only had 
> parameter editor's for partitioning and initialising file systems?

We don't intend to do anything close to what DriveSetup did. We implement 
all functionality related to partition recognition and modification in 
the kernel. DriveSetup did it all in its own add-ons in userland. Our 
userland API basically just mirror the kernel functionality through a neat 
API.

A partition has two sets of parameters:

1. The ones assigned by the partitioning system that created the 
partition. In case of the Intel partitioning system that would include the 
"active" flag for the partition. This set of parameters is just called 
"parameters".

2. The parameters assigned by the disk system that has initialized the 
partition. E.g. in case of a BFS partition that would include things like 
the block size, whether to support indices and the like. This set of 
parameters is called "content parameters".

BPartition::Get[Content]ParameterEditor() shall return an editor that 
allows for editing the parameters/content parameters of an already 
existing/initialized partition. Whether they can really be changed depends 
on the disk system. E.g. the "active" flag should pose no problem, but the 
block size or index support probably will.

BPartition::GetInitializationParameterEditor() returns an editor that 
allows editing the content parameters for a partition that is going to be 
initialized. BPartition::GetChildCreationParameterEditor() returns an 
editor that allows editing the parameters for a partition that is going to 
be created.

> This confusion is further compounded by the fact that nobody seems to have 
> implemented BDiskDeviceParameterEditor. Yikes!

BDiskDeviceParameter will only be a small abstract base class. Derived 
classes will be implemented in userland add-ons for the different 
partitioning and file systems. They'll basically have to provide a BView 
with controls allowing the user to edit the specific parameters of that 
disk system.

> Looking a bit further, i found this rather interesting PartitioningDialog 
> class, which seemed to require a BDiskScannerParameterEditor. "Great!" i 
> thought, "Maybe i can use this to at least have a partitioning dialog?". 
> Sadly though, it seems the only way i can get an instance of a 
> BDiskScannerParameterEditor is by invoking a non-existent (or rather, 
> commented out and not implemented) BDiskScannerPartitionAddOn::CreateEditor 
> function, which even references a BSession class, which like the 
> BDiskScannerParameterEditor i cannot find anywhere.

This API is obsolete and will be removed.

> So to summarise, there seems to be two possible ways i can modify partition's 
> or initialise file systems, non of which are really implemented.
>
> Anyone have any thoughts or suggestions on this rather dreadful situation?

Yep, I'm working on it.

It might not be so good an idea to work on DriveSetup ATM. The GUI 
currently looks pretty much like a clone of BeOS's DriveSetup, but I don't 
think ours should look and work like this.

CU, Ingo