From 6c355c80d31b5b3bb0cfcaf72575f20c6e3a75e7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ciro=20Santilli=20=E5=85=AD=E5=9B=9B=E4=BA=8B=E4=BB=B6=20?=
 =?UTF-8?q?=E6=B3=95=E8=BD=AE=E5=8A=9F?= <ciro.santilli@gmail.com>
Date: Sat, 10 Nov 2018 00:00:00 +0000
Subject: [PATCH] qemu-monitor: migrate to Python!

Just came across the telnet in the stdlib, and got rid of the ugly expect
dependency, nice.

Also implement stdin input now that we have a sane language.
---
 README.adoc           |  8 ++++--
 download-dependencies |  3 +-
 qemu-monitor          | 66 ++++++++++++++++++++++++++++---------------
 3 files changed, 50 insertions(+), 27 deletions(-)

diff --git a/README.adoc b/README.adoc
index 9525eb9..7021a84 100644
--- a/README.adoc
+++ b/README.adoc
@@ -8017,12 +8017,16 @@ or send one command such as `info qtree` and quit the monitor:
 ./qemu-monitor info qtree
 ....
 
+or equivalently:
+
+....
+echo 'info qtree' | ./qemu-monitor
+....
+
 Source: link:qemu-monitor[]
 
 `qemu-monitor` uses the `-monitor` QEMU command line option, which makes the monitor listen from a socket.
 
-`qemu-monitor` does not support input from an stdin pipe currently, see comments on the source for rationale.
-
 Alternatively, from text mode:
 
 ....
diff --git a/download-dependencies b/download-dependencies
index defe44b..cde674b 100755
--- a/download-dependencies
+++ b/download-dependencies
@@ -88,9 +88,9 @@ automake \
 bc \
 bison \
 build-essential \
+ccache \
 coreutils \
 cpio \
-expect \
 flex \
 gcc-aarch64-linux-gnu \
 gcc-arm-linux-gnueabihf \
@@ -114,7 +114,6 @@ pexpect==4.6.0 \
 "
   if "$gem5"; then
     pkgs="${pkgs}\
-ccache \
 diod \
 libgoogle-perftools-dev \
 protobuf-compiler \
diff --git a/qemu-monitor b/qemu-monitor
index 9ef4aed..a2bcd9d 100755
--- a/qemu-monitor
+++ b/qemu-monitor
@@ -1,24 +1,44 @@
-#!/usr/bin/env expect
-# Ee have to use expect since QEMU 2.12: just piping commands
-# into telnet stopped working at that version.
-spawn telnet localhost 45454
-set prompt "\n(qemu) "
-expect $prompt
-if {$argc > 0} {
-  send "[concat [join $argv " "]]\r"
-  expect $prompt
-} else {
-  interact
-}
+#!/usr/bin/env python3
 
-# In order to treat input from stdin, we would need to differentiate between input from pipe vs terminal.
-# For bash we can do it as:
-# https://stackoverflow.com/questions/911168/how-to-detect-if-my-shell-script-is-running-through-a-pipe
-# but no one knows for Tcl:
-# https://stackoverflow.com/questions/43660612/how-to-check-if-stdin-stdout-are-connected-to-a-terminal-in-tcl
-# One option would also be to have a bash wrapper that calls this tcl script.
-# Related: https://stackoverflow.com/questions/10237872/expect-redirect-stdin
-#while {[gets stdin line] > 0} {
-  #expect $prompt
-  #send "$line\r"
-#}
+import os
+import sys
+import telnetlib
+
+import common
+
+prompt = b'\n(qemu) '
+
+parser = common.get_argparse({
+    'description': '''\
+Run a command on the QEMU monitor of a running QEMU instance
+
+If the stdin is a terminal, open an interact shell. Otherwise,
+run commands from stdin and quit.
+'''
+})
+parser.add_argument(
+    'command',
+    help='If given, run this command and quit',
+    nargs='*',
+)
+args = common.setup(parser)
+
+def write_and_read(tn, cmd, prompt):
+    tn.write(cmd.encode('utf-8'))
+    return '\n'.join(tn.read_until(prompt).decode('utf-8').splitlines()[1:])[:-len(prompt)]
+
+with telnetlib.Telnet('localhost', common.qemu_monitor_port) as tn:
+    # Couldn't disable server echo, so just removing the write for now.
+    # https://stackoverflow.com/questions/12421799/how-to-disable-telnet-echo-in-python-telnetlib
+    # sock = tn.get_socket()
+    # sock.send(telnetlib.IAC + telnetlib.WILL + telnetlib.ECHO)
+    if os.isatty(sys.stdin.fileno()):
+        if args.command == []:
+            print(tn.read_until(prompt).decode('utf-8'), end='')
+            tn.interact()
+        else:
+            tn.read_until(prompt)
+            print(write_and_read(tn, ' '.join(args.command) + '\n', prompt))
+    else:
+        tn.read_until(prompt)
+        print(write_and_read(tn, sys.stdin.read() + '\n', prompt))