This implements getvar all by invoking each callback and writing an INFO
status for each result. For commands that take arguments, the variable
handler can specify a function that returns all possible arguments.
Currently this only applies to partition variables.
Bug: 78793464
Test: fastboot getvar all works
Change-Id: I1cf84e06bf67614b6f56171c0ee6ca5d7ac383c9
It is easier to implement getvar all if we can invoke each variable
handler and collect their results. This change reverts the handlers to
return their messages as an outparam, rather than going through
FastbootDevice.
Bug: 78793464
Test: fastboot getvar works
Change-Id: I8544251ce517526b26435526756359ce220520cc
Currently a few getvar handlers will return invalid strings when an
error occurs. This change allows those handlers to instead send a proper
failure message.
Bug: 78793464
Test: N/A
Change-Id: I7ff7d036c1e6fb0a3d700ecf21b1103ab77278d2