WIP: api/socket: Add Go types for the command-line API socket messages

Even though there aren't many new types, these are fairly different
from the rest of the runtime-tools code, and a separate package lets
folks pull in only the code they need (assuming they are sophisticated
enough to grab only a subset of the Git repository).

Still needs a place to store the JSON Schemas [1].

[1]: https://github.com/opencontainers/runtime-spec/pull/513/files#diff-751d571a4cba0b0155c3d3bf793e08e8R13

Signed-off-by: W. Trevor King <wking@tremily.us>

Author: wking

api/socket/socket.go

@@ -0,0 +1,23 @@
+package socket
+
+// Message is the normal data for messages passed on the console socket.
+type Message struct {
+	// Type of message being passed
+	Type string `json:"type"`
+}
+
+// TerminalRequest is the normal data for messages passing a pseudoterminal master.
+type TerminalRequest struct {
+	Message
+
+	// Container ID for the container whose pseudoterminal master is being set.
+	Container string `json:"container"`
+}
+
+// Response is the normal data for response messages.
+type Response struct {
+	Message
+
+	// Message is a phrase describing the response.
+	Message string `json:"message,omitempty"`
+}

docs/command-line-interface.md

@@ -85,7 +85,7 @@ The socket type MUST be [`SOCK_SEQPACKET`][socket-types] or [`SOCK_STREAM`][sock
 The server MUST send a single response for each runtime request.
 The [normal data][socket-queue] ([`msghdr.msg_iov*`][socket.h]) of all messages MUST be [UTF-8][] [JSON](glossary.md#json).
 
-There are [JSON Schemas](schema/README.md) and [Go bindings](specs-go/socket/socket.go) for the messages specified in this section.
+There are [JSON Schemas](schema/README.md FIXME) and [Go bindings](../api/socket/socket.go) for the messages specified in this section.
 
 ##### Requests