QEMU tools cannot run in the app process on iOS: a process may load QEMU
only once and qemu-img calls exit(). So disk snapshots of a stopped VM,
reclaiming space, compression, resizing and conversion on import were
macOS-only.
iOS 26 brings ExtensionKit, so qemu-img now runs in an ExtensionKit
extension (iOSHelper, and iOSHelper-SE for UTM SE since an extension's
bundle identifier must be prefixed by its host's). The helper speaks the
same QEMUHelperProtocol as the macOS XPC helper but loads the tool into
its own process, one tool per process. UTMProcess accepts an injected
connection so the remote path is shared with macOS, including file
access through bookmarks, whose implicit security scope grants the
resolving process access. UTMHelperProcess launches the helper and,
because the system hands a process that is still exiting to a launch
that comes too soon, tears it down with a handshake on the interruption
callback and runs helpers one at a time.
UTMQemuImage now reads the tool's output until it ends instead of
racing the exit message, resumes its continuations off the XPC reply
queue (a call made from that queue blocks in NSXPC), and stops the
process explicitly since the connection's exported object kept it from
ever being deallocated on macOS. The last stderr line becomes the error
text when the tool gives none.
Assisted-by: Claude:claude-fable-5-1
osy