A fifo on unix or named pipe on Windows will be provided to the shim.
It can be located inside the `cwd` of the shim named "log".
The shims can use the existing `github.com/containerd/containerd/log` package to log debug messages.
Messages will automatically be output in the containerd's daemon logs with the correct fiels and runtime set.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
1. Moves the log message for each socket to the appropriate _unix and
_windows.go
2. Replaces all reference to Abstract Socket for Windows.
3. Adds support for ctrl+c on Windows to exit a shim.
Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>
