It's actually quite hard to build a front-end for fwupd at the moment
as you're never sure when the progress bar is going to zip back to 0%
and start all over again. Some plugins go 0..100% for write, others
go 0..100% for erase, then again for write, then *again* for verify.
By creating a helper object we can easily split up the progress of the
specific task, e.g. write_firmware().
We can encode at the plugin level "the erase takes 50% of the time, the
write takes 40% and the read takes 10%". This means we can have a
progressbar which goes up just once at a consistent speed.
Before this change calling FuUsbDevice->open() opened the device, and
also unconditionally added various GUIDs and InstanceIDs which we
normally do in setup.
Then fu_device_setup() would call the FuSubclass->setup() vfunc which
would have no way of either opting out of the FuUsbDevice->setup()-like
behaviour, or controlling if the parent class ->setup is run before or
after the subclass setup.
Split up FuUsbDevice->open() into clear ->open() and ->setup() phases
and add the parent class calls where appropriate.
This means that ->setup() now behaves the same as all the other vfuncs.
This allows us to 'nest' firmware formats, and removes a ton of duplication.
The aim here is to deprecate FuFirmwareImage -- it's almost always acting
as a 'child' FuFirmware instance, and even copies most of the vfuncs to allow
custom types. If I'm struggling to work out what should be a FuFirmware and
what should be a FuFirmwareImage then a plugin author has no hope.
For simple payloads we were adding bytes into an image and then the image into
a firmware. This gets really messy when most plugins are treating the FuFirmware
*as* the binary firmware file.
The GBytes saved in the FuFirmware would be considered the payload with the
aim of not using FuFirmwareImage in the single-image case.
Devices may want to support more than one protocol, and for some devices
(e.g. Unifying peripherals stuck in bootloader mode) you might not even be able
to query for the correct protocol anyway.
At the moment FuChunks are sometimes mutable, and sometimes immutable, and it's
all a bit too low level for comfort.
Before we can do any kind of optimisation or verification we need plugins to
stop reading directly from the C structure. The aim here is to make FuChunk
optionally mutable without making assumptions about the memory model, and also
to be able to introspect it for the docs.
This is nice in theory, until you need to look at the bootloader status of the
parent, or of a different device entirely. Handle this in plugins for the few
cases we care about and stop setting or clearing IS_BOOTLOADER manually just to
get the vfuncs to be run.
Note: I do not think we want to use cleanup() for attaching devices not in
bootloader states -- as cleanup is only run at the end of the composite update.
