Set errno in NetworkController commands.

Set errno in the NetworkController functions that are called by
CommandListener and where failure causes an operationError. This
is because operationError always appends errno to its messages,
and

"400 481 addInterfaceToNetwork() failed (Device or resource busy)"

is more useful than:

"400 481 addInterfaceToNetwork() failed (Success)"

We already call ALOGE to put descriptive messages in the system
log, but the bugreport already conveniently aggregates all netd
commands in one place in the network_management service dump, and
it would help if the errno in those messages were accurate.

Unfortunately many of the route and iptables commands shell out
to /sbin/ip and we can't return meaningful values, but we'll
fix that when (if?) we replace that with a proper netlink
implementation.

Bug: 15316764
Change-Id: Ia47f451029d611491aa72bca602de77333f2c6a0
2 files changed
tree: fb2eddc17789984cc2bb1e41bad7a7c32cb1bf7f
  1. client/
  2. include/
  3. server/