332 lines
12 KiB
Scheme
332 lines
12 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu build marionette)
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#:use-module (srfi srfi-9)
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#:use-module (srfi srfi-26)
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#:use-module (rnrs io ports)
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#:use-module (ice-9 match)
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#:use-module (ice-9 popen)
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#:export (marionette?
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make-marionette
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marionette-eval
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wait-for-file
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wait-for-tcp-port
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marionette-control
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marionette-screen-text
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wait-for-screen-text
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%qwerty-us-keystrokes
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marionette-type))
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;;; Commentary:
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;;;
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;;; Instrumentation tools for QEMU virtual machines (VMs). A "marionette" is
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;;; essentially a VM (a QEMU instance) with its monitor connected to a
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;;; Unix-domain socket, and with a REPL inside the guest listening on a
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;;; virtual console, which is itself connected to the host via a Unix-domain
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;;; socket--these are the marionette's strings, connecting it to the almighty
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;;; puppeteer.
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;;;
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;;; Code:
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(define-record-type <marionette>
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(marionette command pid monitor repl)
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marionette?
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(command marionette-command) ;list of strings
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(pid marionette-pid) ;integer
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(monitor marionette-monitor) ;port
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(repl %marionette-repl)) ;promise of a port
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(define-syntax-rule (marionette-repl marionette)
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(force (%marionette-repl marionette)))
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(define* (wait-for-monitor-prompt port #:key (quiet? #t))
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"Read from PORT until we have seen all of QEMU's monitor prompt. When
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QUIET? is false, the monitor's output is written to the current output port."
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(define full-prompt
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(string->list "(qemu) "))
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(let loop ((prompt full-prompt)
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(matches '())
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(prefix '()))
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(match prompt
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(()
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;; It's useful to set QUIET? so we don't display the echo of our own
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;; commands.
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(unless quiet?
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(for-each (lambda (line)
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(format #t "qemu monitor: ~a~%" line))
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(string-tokenize (list->string (reverse prefix))
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(char-set-complement (char-set #\newline))))))
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((chr rest ...)
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(let ((read (read-char port)))
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(cond ((eqv? read chr)
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(loop rest (cons read matches) prefix))
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((eof-object? read)
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(error "EOF while waiting for QEMU monitor prompt"
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(list->string (reverse prefix))))
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(else
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(loop full-prompt
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'()
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(cons read (append matches prefix))))))))))
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(define* (make-marionette command
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#:key (socket-directory "/tmp") (timeout 20))
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"Return a QEMU marionette--i.e., a virtual machine with open connections to the
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QEMU monitor and to the guest's backdoor REPL."
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(define (file->sockaddr file)
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(make-socket-address AF_UNIX
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(string-append socket-directory "/" file)))
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(define extra-options
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(list "-nographic"
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"-monitor" (string-append "unix:" socket-directory "/monitor")
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"-chardev" (string-append "socket,id=repl,path=" socket-directory
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"/repl")
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;; See
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;; <http://www.linux-kvm.org/page/VMchannel_Requirements#Invocation>.
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"-device" "virtio-serial"
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"-device" "virtserialport,chardev=repl,name=org.gnu.guix.port.0"))
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(define (accept* port)
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(match (select (list port) '() (list port) timeout)
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(((port) () ())
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(accept port))
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(_
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(error "timeout in 'accept'" port))))
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(let ((monitor (socket AF_UNIX SOCK_STREAM 0))
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(repl (socket AF_UNIX SOCK_STREAM 0)))
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(bind monitor (file->sockaddr "monitor"))
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(listen monitor 1)
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(bind repl (file->sockaddr "repl"))
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(listen repl 1)
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(match (primitive-fork)
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(0
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(catch #t
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(lambda ()
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(close monitor)
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(close repl)
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(match command
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((program . args)
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(apply execl program program
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(append args extra-options)))))
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(lambda (key . args)
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(print-exception (current-error-port)
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(stack-ref (make-stack #t) 1)
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key args)
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(primitive-exit 1))))
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(pid
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(format #t "QEMU runs as PID ~a~%" pid)
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(match (accept* monitor)
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((monitor-conn . _)
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(display "connected to QEMU's monitor\n")
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(close-port monitor)
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(wait-for-monitor-prompt monitor-conn)
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(display "read QEMU monitor prompt\n")
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(marionette (append command extra-options) pid
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monitor-conn
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;; The following 'accept' call connects immediately, but
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;; we don't know whether the guest has connected until
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;; we actually receive the 'ready' message.
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(match (accept* repl)
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((repl-conn . addr)
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(display "connected to guest REPL\n")
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(close-port repl)
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;; Delay reception of the 'ready' message so that the
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;; caller can already send monitor commands.
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(delay
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(match (read repl-conn)
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('ready
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(display "marionette is ready\n")
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repl-conn))))))))))))
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(define (marionette-eval exp marionette)
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"Evaluate EXP in MARIONETTE's backdoor REPL. Return the result."
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(match marionette
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(($ <marionette> command pid monitor (= force repl))
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(write exp repl)
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(newline repl)
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(read repl))))
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(define* (wait-for-file file marionette
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#:key (timeout 10) (read 'read))
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"Wait until FILE exists in MARIONETTE; READ its content and return it. If
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FILE has not shown up after TIMEOUT seconds, raise an error."
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(match (marionette-eval
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`(let loop ((i ,timeout))
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(cond ((file-exists? ,file)
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(cons 'success (call-with-input-file ,file ,read)))
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((> i 0)
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(sleep 1)
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(loop (- i 1)))
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(else
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'failure)))
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marionette)
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(('success . result)
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result)
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('failure
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(error "file didn't show up" file))))
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(define* (wait-for-tcp-port port marionette
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#:key (timeout 20))
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"Wait for up to TIMEOUT seconds for PORT to accept connections in
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MARIONETTE. Raise an error on failure."
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;; Note: The 'connect' loop has to run within the guest because, when we
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;; forward ports to the host, connecting to the host never raises
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;; ECONNREFUSED.
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(match (marionette-eval
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`(begin
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(let ((sock (socket PF_INET SOCK_STREAM 0)))
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(let loop ((i 0))
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(catch 'system-error
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(lambda ()
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(connect sock AF_INET INADDR_LOOPBACK ,port)
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'success)
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(lambda args
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(if (< i ,timeout)
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(begin
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(sleep 1)
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(loop (+ 1 i)))
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'failure))))))
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marionette)
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('success #t)
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('failure
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(error "nobody's listening on port" port))))
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(define (marionette-control command marionette)
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"Run COMMAND in the QEMU monitor of MARIONETTE. COMMAND is a string such as
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\"sendkey ctrl-alt-f1\" or \"screendump foo.ppm\" (info \"(qemu-doc)
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pcsys_monitor\")."
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(match marionette
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(($ <marionette> _ _ monitor)
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(display command monitor)
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(newline monitor)
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(wait-for-monitor-prompt monitor))))
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(define* (marionette-screen-text marionette
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#:key
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(ocrad "ocrad"))
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"Take a screenshot of MARIONETTE, perform optical character
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recognition (OCR), and return the text read from the screen as a string. Do
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this by invoking OCRAD (file name for GNU Ocrad's command)"
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(define (random-file-name)
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(string-append "/tmp/marionette-screenshot-"
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(number->string (random (expt 2 32)) 16)
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".ppm"))
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(let ((image (random-file-name)))
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(dynamic-wind
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(const #t)
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(lambda ()
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(marionette-control (string-append "screendump " image)
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marionette)
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;; Tell Ocrad to invert the image colors (make it black on white) and
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;; to scale the image up, which significantly improves the quality of
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;; the result. In spite of this, be aware that OCR confuses "y" and
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;; "V" and sometimes erroneously introduces white space.
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(let* ((pipe (open-pipe* OPEN_READ ocrad
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"-i" "-s" "10" image))
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(text (get-string-all pipe)))
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(unless (zero? (close-pipe pipe))
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(error "'ocrad' failed" ocrad))
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text))
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(lambda ()
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(false-if-exception (delete-file image))))))
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(define* (wait-for-screen-text marionette predicate
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#:key (timeout 30) (ocrad "ocrad"))
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"Wait for TIMEOUT seconds or until the screen text on MARIONETTE matches
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PREDICATE, whichever comes first. Raise an error when TIMEOUT is exceeded."
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(define start
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(car (gettimeofday)))
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(define end
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(+ start timeout))
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(let loop ()
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(if (> (car (gettimeofday)) end)
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(error "'wait-for-screen-text' timeout" predicate)
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(or (predicate (marionette-screen-text marionette #:ocrad ocrad))
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(begin
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(sleep 1)
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(loop))))))
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(define %qwerty-us-keystrokes
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;; Maps "special" characters to their keystrokes.
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'((#\newline . "ret")
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(#\space . "spc")
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(#\- . "minus")
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(#\+ . "shift-equal")
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(#\* . "shift-8")
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(#\= . "equal")
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(#\? . "shift-slash")
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(#\[ . "bracket_left")
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(#\] . "bracket_right")
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(#\( . "shift-9")
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(#\) . "shift-0")
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(#\/ . "slash")
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(#\< . "less")
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(#\> . "shift-less")
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(#\. . "dot")
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(#\, . "comma")
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(#\; . "semicolon")
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(#\' . "apostrophe")
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(#\" . "shift-apostrophe")
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(#\` . "grave_accent")
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(#\bs . "backspace")
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(#\tab . "tab")))
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(define (character->keystroke chr keystrokes)
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"Return the keystroke for CHR according to the keyboard layout defined by
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KEYSTROKES."
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(if (char-set-contains? char-set:upper-case chr)
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(string-append "shift-" (string (char-downcase chr)))
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(or (assoc-ref keystrokes chr)
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(string chr))))
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(define* (string->keystroke-commands str
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#:optional
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(keystrokes
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%qwerty-us-keystrokes))
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"Return a list of QEMU monitor commands to send the keystrokes corresponding
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to STR. KEYSTROKES is an alist specifying a mapping from characters to
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keystrokes."
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(string-fold-right (lambda (chr result)
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(cons (string-append
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"sendkey "
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(character->keystroke chr keystrokes))
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result))
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'()
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str))
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(define* (marionette-type str marionette
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#:key (keystrokes %qwerty-us-keystrokes))
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"Type STR on MARIONETTE's keyboard, using the KEYSTROKES alist to map characters
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to actual keystrokes."
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(for-each (cut marionette-control <> marionette)
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(string->keystroke-commands str keystrokes)))
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;;; marionette.scm ends here
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