defined a common interface for nativeimgutil & qemuimgutil

[Horiodino]

fixes : #3518

Define the common interface for qemuimgutil and nativeimgutil

[Copilot]

Pull Request Overview

This PR refactors image utility handling by defining a common interface for both native and QEMU image utilities, allowing the code to use a unified API for disk image operations. Key changes include replacing direct calls to nativeimgutil and qemuimgutil with calls to the common imgutil package, introducing factory and proxy implementations, and updating tests and error handling accordingly.

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg/vz/vm_darwin.go	Replaced nativeimgutil with common imgutil for raw disk conversion.
pkg/vz/disk.go	Updated disk creation and resizing to use the new imgutil interface.
pkg/qemu/qemu.go	Refactored disk info retrieval and validation to use the proxy interface.
pkg/instance/start.go	Updated disk conversion logic to use the common image utility.
pkg/imgutil/qemuimgutil/*	Renamed helper functions to unexported versions and updated tests.
pkg/imgutil/nativeimgutil/*	Adjusted naming of internal functions and updated tests accordingly.
pkg/imgutil/proxyimgutil/*	Introduced proxy implementation to abstract native/qemu differences.
pkg/imgutil/factory.go	Added a factory function to return the correct image util based on format.
cmd/limactl/disk.go	Updated command-line disk actions to use the new unified API.

Comments suppressed due to low confidence (2)

pkg/qemu/qemu.go:95

• [nitpick] If multiple image info calls occur within this function, consider caching the result of NewImageUtil to avoid redundant initialization overhead.

	_, infoProvider, err := imgutil.NewImageUtil("qcow2")

pkg/instance/start.go:429

• [nitpick] If prepareDiffDisk is called frequently, consider caching the image util instance to reduce the cost of repetitive initialization.

	diskUtil, _, err := imgutil.NewImageUtil(format)

[AkihiroSuda]

Doesn't seem to follow #3518

[AkihiroSuda]

When qemu.CreateDisk returns an error other than exec.ErrNotFound, the error should be returned immediately without falling back to native.CreateDisk?

[AkihiroSuda]

Same applies to other functions too

[AkihiroSuda]

exitError.ExitCode() == 127

How does this happen?

[Horiodino]

Ok heres the explanation , see in go exec.Command("non existent command")
This results in exec.ErrNotFound because Go cannot find the command itself. It never even starts running because the binary doesn't exist.

exec.Command("sh", "-c", "non existent command"):
Here, sh exists, but the command inside the shell (nonexistentcommand) doesn't exist. So, the shell runs but exits with exit code 127, which means "command not found inside the shell."

exec.ErrNotFound for missing executables.

Exit code 127 when the executable runs but the command inside it is missing.

[AkihiroSuda]

How is sh relevant here?

[Horiodino]

I used sh just as a common example to illustrate the behavior.

The 127 exit code is simply a valid, standardized way to indicate "command not found" it's a safe and predictable way to signal failure without causing unexpected behavior.

In this case, yeah the failure scenario I described doesn't really apply here. I included it more as an extra precaution.

[AkihiroSuda]

The commits can be squashed