gbhub: control socket + gbtype to inject shell input without the OSK

Typing into a Game Boy meant driving the on-screen keyboard by hand. But
the link port already *is* the shell's console: bytes the hub sends
un-SLIP-framed land straight on stdin (that's what GB.type() has always
done for spawn-mode command scripting). This just exposes it.

gbhub now serves a control socket (/tmp/gbhub.ctl, world-connectable like
the join socket) accepting two commands: 'list' and 'type [idx]' followed
by a payload (delimited by the client's half-close). Injection is chunked
and paced to respect the 64-byte kernel console ring, so arbitrarily long
input - even multi-line scripts - reaches the shell without overflow. The
server runs in both daemon and spawn modes.

tools/gbtype is the client:
  tools/gbtype 'ls -l'        run a command on GB0 (Enter appended)
  tools/gbtype -g 1 ps        target the Nth joined Game Boy
  tools/gbtype -n abc         no trailing Enter
  tools/gbtype -r             just press Enter
  tools/gbtype -l             list connected Game Boys
  printf 'ls\nuname\n' | tools/gbtype    pipe a script via stdin

Options precede the command; the first non-option word starts literal
text, so 'gbtype ls -l' needs no quoting. No root required.

Verified end to end: injected list/uname/echo through the real CTL
protocol and saw the shell execute each and echo output back.

1 files changed, 79 insertions, 0 deletions

diff --git a/tools/gbtype b/tools/gbtype
new file mode 100755
index 0000000..f58a1f8
--- /dev/null
+++ b/tools/gbtype
@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""gbtype - inject shell input into a running gbhub Game Boy, no OSK needed.
+
+The Game Boy's link port *is* its console when nothing SLIP-frames the bytes,
+so text sent over the hub's control socket lands straight on the shell's stdin
+- exactly as if typed on the on-screen keyboard, but driven from your host.
+
+Start the hub first (in another terminal):   sudo tools/gbhub --daemon
+
+  tools/gbtype 'ls -l'         run 'ls -l' on GB0 (a trailing Enter is added)
+  tools/gbtype -g 1 ps         target GB1 (the Nth joined Game Boy)
+  tools/gbtype -n abc          type 'abc' but no Enter (leave it on the line)
+  tools/gbtype -r              just press Enter
+  tools/gbtype -l              list the connected Game Boys
+  printf 'ls\\ncat readme\\n' | tools/gbtype     pipe a script via stdin
+
+Options must come before the command; the first non-option word starts the
+literal text (so 'gbtype ls -l' needs no quoting, and '-l' there is not --list).
+No root needed - the hub opens the control socket world-connectable."""
+import os, sys, socket
+
+CTL = "/tmp/gbhub.ctl"
+
+def usage(code=0):
+    (sys.stdout if code == 0 else sys.stderr).write(__doc__ + "\n")
+    sys.exit(code)
+
+def send(header, payload=b""):
+    if not os.path.exists(CTL):
+        sys.exit("gbtype: no hub control socket at %s\n"
+                 "        start it first:  sudo tools/gbhub --daemon" % CTL)
+    s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+    try: s.connect(CTL)
+    except OSError as e: sys.exit("gbtype: cannot connect %s (%s)" % (CTL, e))
+    s.sendall(header + b"\n" + payload)
+    s.shutdown(socket.SHUT_WR)            # end-of-payload marker for the hub
+    out = b""
+    while True:
+        try: d = s.recv(4096)
+        except Exception: break
+        if not d: break
+        out += d
+    s.close()
+    sys.stdout.write(out.decode(errors="replace"))
+
+def main():
+    args = sys.argv[1:]
+    idx = None
+    newline = True
+    i = 0
+    while i < len(args):
+        a = args[i]
+        if a in ("-h", "--help"): usage(0)
+        elif a in ("-l", "--list"): send(b"list"); return
+        elif a in ("-g", "--gb"):
+            i += 1
+            if i >= len(args): usage(1)
+            idx = args[i]
+        elif a in ("-n", "--no-enter"): newline = False
+        elif a in ("-r", "--enter"):
+            send(b"type" + (b" " + idx.encode() if idx else b""), b"\n"); return
+        elif a == "--": i += 1; break
+        elif a.startswith("-") and len(a) > 1:
+            sys.stderr.write("gbtype: unknown option %s\n" % a); usage(1)
+        else: break                       # first positional: rest is literal text
+        i += 1
+
+    words = args[i:]
+    if words:
+        payload = " ".join(words).encode() + (b"\n" if newline else b"")
+    else:
+        payload = sys.stdin.buffer.read()             # piped script, sent verbatim
+        if newline and payload and not payload.endswith(b"\n"):
+            payload += b"\n"
+
+    send(b"type" + (b" " + idx.encode() if idx is not None else b""), payload)
+
+if __name__ == "__main__":
+    main()