From d723d1a8f5738cd163d6ed46671297b2618c897b Mon Sep 17 00:00:00 2001
From: Mikhail Klementev <jollheef@riseup.net>
Date: Tue, 18 Sep 2018 21:45:21 +0000
Subject: [PATCH] Implements start/stop

---
 qemu-kernel.go      | 144 ++++++++++++++++++++++++++++++++++++++++++++
 qemu-kernel_test.go |  47 +++++++++++++++
 2 files changed, 191 insertions(+)
 create mode 100644 qemu-kernel.go
 create mode 100644 qemu-kernel_test.go

diff --git a/qemu-kernel.go b/qemu-kernel.go
new file mode 100644
index 0000000..0738049
--- /dev/null
+++ b/qemu-kernel.go
@@ -0,0 +1,144 @@
+// Copyright 2018 Mikhail Klementev. All rights reserved.
+// Use of this source code is governed by a GPLv3 license
+// (or later) that can be found in the LICENSE file.
+
+package qemukernel
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"syscall"
+	"time"
+)
+
+func readBytesUntilEOF(pipe io.ReadCloser) (buf []byte, err error) {
+	bufSize := 1024
+	for err != io.EOF {
+		stdout := make([]byte, bufSize)
+		var n int
+
+		n, err = pipe.Read(stdout)
+		if err != nil && err != io.EOF {
+			return
+		}
+
+		buf = append(buf, stdout[:n]...)
+	}
+
+	if err == io.EOF {
+		err = nil
+	}
+	return
+}
+
+func readUntilEOF(pipe io.ReadCloser) (str string, err error) {
+	buf, err := readBytesUntilEOF(pipe)
+	str = string(buf)
+	return
+}
+
+type arch string
+
+const (
+	X86_64 arch = "x86_64"
+	I386        = "i386"
+	// TODO add other
+
+	unsupported = "unsupported" // for test purposes
+)
+
+// Kernel describe kernel parameters for qemu
+type Kernel struct {
+	Name string
+	Path string
+}
+
+// QemuSystem describe qemu parameters and runned process
+type QemuSystem struct {
+	arch   arch
+	kernel Kernel
+
+	// accessible while qemu is runned
+	cmd  *exec.Cmd
+	pipe struct {
+		stdin  io.WriteCloser
+		stderr io.ReadCloser
+		stdout io.ReadCloser
+	}
+	died bool
+
+	// accessible after qemu is closed
+	Stdout, Stderr string
+	exitErr        error
+}
+
+// NewQemuSystem constructor
+func NewQemuSystem(arch arch, kernel Kernel) (q QemuSystem, err error) {
+	if _, err = exec.LookPath("qemu-system-" + string(arch)); err != nil {
+		return
+	}
+	q.arch = arch
+
+	if _, err = os.Stat(kernel.Path); err != nil {
+		return
+	}
+	q.kernel = kernel
+
+	return
+}
+
+// Start qemu process
+func (q *QemuSystem) Start() (err error) {
+	q.cmd = exec.Command("qemu-system-"+string(q.arch),
+		// TODO
+		"-snapshot",
+		"-nographic")
+
+	if q.pipe.stdin, err = q.cmd.StdinPipe(); err != nil {
+		return
+	}
+
+	if q.pipe.stdout, err = q.cmd.StdoutPipe(); err != nil {
+		return
+	}
+
+	if q.pipe.stderr, err = q.cmd.StderrPipe(); err != nil {
+		return
+	}
+
+	err = q.cmd.Start()
+	if err != nil {
+		return
+	}
+
+	go func() {
+		q.Stdout, _ = readUntilEOF(q.pipe.stdout)
+		q.Stderr, _ = readUntilEOF(q.pipe.stderr)
+		q.exitErr = q.cmd.Wait()
+		q.died = true
+	}()
+
+	time.Sleep(time.Second / 10) // wait for immediately die
+
+	if q.died {
+		err = errors.New("qemu died immediately: " + q.Stderr)
+	}
+
+	return
+}
+
+// Stop qemu process
+func (q *QemuSystem) Stop() {
+	// 1  00/01   01  01  SOH  (Ctrl-A)  START OF HEADING
+	fmt.Fprintf(q.pipe.stdin, "%cx", 1)
+	// wait for die
+	time.Sleep(time.Second / 10)
+	if !q.died {
+		q.cmd.Process.Signal(syscall.SIGTERM)
+		time.Sleep(time.Second / 10)
+		q.cmd.Process.Signal(syscall.SIGKILL)
+	}
+}
diff --git a/qemu-kernel_test.go b/qemu-kernel_test.go
new file mode 100644
index 0000000..cd797b1
--- /dev/null
+++ b/qemu-kernel_test.go
@@ -0,0 +1,47 @@
+// Copyright 2018 Mikhail Klementev. All rights reserved.
+// Use of this source code is governed by a GPLv3 license
+// (or later) that can be found in the LICENSE file.
+
+package qemukernel
+
+import (
+	"testing"
+)
+
+func TestQemuSystemNew_InvalidKernelPath(t *testing.T) {
+	kernel := Kernel{Name: "Invalid", Path: "/invalid/path"}
+	if _, err := NewQemuSystem(X86_64, kernel); err == nil {
+		t.Fatal(err)
+	}
+}
+
+func TestQemuSystemNew_InvalidQemuArch(t *testing.T) {
+	// FIXME put kernel image to path not just "any valid path"
+	kernel := Kernel{Name: "Valid path", Path: "/bin/sh"}
+	if _, err := NewQemuSystem(unsupported, kernel); err == nil {
+		t.Fatal(err)
+	}
+}
+
+func TestQemuSystemNew(t *testing.T) {
+	// FIXME put kernel image to path not just "any valid path"
+	kernel := Kernel{Name: "Valid path", Path: "/bin/sh"}
+	if _, err := NewQemuSystem(X86_64, kernel); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestQemuSystemStart(t *testing.T) {
+	// TODO check kernel path on other distros than gentoo
+	kernel := Kernel{Name: "Host kernel", Path: "/boot/vmlinuz-4.18.8"}
+	qemu, err := NewQemuSystem(X86_64, kernel)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err = qemu.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	qemu.Stop()
+}