Back targetEnvCommand() with a more general runCommand()
that takes an argument selecting the location to run
the command in. This allows us also to use the same
API for running processes in the host during install,
as we do for running them in the target system.
One reason for this change is wanting to run (user-specified)
commands and independently from the global dontChroot setting,
run those commands in the live system or the target.
This changes the ABI of the DLL, since targetEnvCommand()
is no longer exported. Plugins will need to be recompiled.
- refactor targetEnvCommand() into more general runCommand().
- While here, allow host system commands to run even if
there is no global storage.
- provide convenience accessors for ProcessResult members
- Move explanation of process errors out of ProcessJob
- Move from ProcessJob to ProcessResult, so it can be
reused outside of ProcessJob (e.g. from ShellProcessJob).
- Add some convenience functions, too.
