reboot --kexec almost works

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

cmd/control/install/syslinux.go

@@ -1,9 +1,13 @@
 package install
 
 import (
+	"bufio"
+	"bytes"
 	"html/template"
+	"io/ioutil"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/rancher/os/log"
 )
@@ -43,3 +47,48 @@ DEFAULT RancherOS-current
 	}
 	return nil
 }
+
+func ReadGlobalCfg(globalCfg string) (string, error) {
+	append := ""
+	buf, err := ioutil.ReadFile(globalCfg)
+	if err != nil {
+		return append, err
+	}
+
+	s := bufio.NewScanner(bytes.NewReader(buf))
+	for s.Scan() {
+		line := strings.TrimSpace(s.Text())
+		if strings.HasPrefix(line, "APPEND") {
+			append = strings.TrimSpace(strings.TrimPrefix(line, "APPEND"))
+		}
+	}
+	return append, nil
+}
+
+func ReadSyslinuxCfg(currentCfg string) (string, string, error) {
+	vmlinuzFile := ""
+	initrdFile := ""
+	// Need to parse currentCfg for the lines:
+	// KERNEL ../vmlinuz-4.9.18-rancher^M
+	// INITRD ../initrd-41e02e6-dirty^M
+	buf, err := ioutil.ReadFile(currentCfg)
+	if err != nil {
+		return vmlinuzFile, initrdFile, err
+	}
+
+	DIST := filepath.Dir(currentCfg)
+
+	s := bufio.NewScanner(bytes.NewReader(buf))
+	for s.Scan() {
+		line := strings.TrimSpace(s.Text())
+		if strings.HasPrefix(line, "KERNEL") {
+			vmlinuzFile = strings.TrimSpace(strings.TrimPrefix(line, "KERNEL"))
+			vmlinuzFile = filepath.Join(DIST, filepath.Base(vmlinuzFile))
+		}
+		if strings.HasPrefix(line, "INITRD") {
+			initrdFile = strings.TrimSpace(strings.TrimPrefix(line, "INITRD"))
+			initrdFile = filepath.Join(DIST, filepath.Base(initrdFile))
+		}
+	}
+	return vmlinuzFile, initrdFile, err
+}