feat: Add basic inittab support

inittab.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"bufio"
+	"io"
+	"strings"
+)
+
+type Action uint8
+
+const (
+	SysInit Action = iota
+	Wait
+	Once
+	Respawn
+	AskFirst
+	Shutdown
+	Restart
+	CtrlAltDel
+)
+
+var ActionMap = map[string]Action{
+	"sysinit":    SysInit,
+	"wait":       Wait,
+	"once":       Once,
+	"respawn":    Respawn,
+	"askfirst":   AskFirst,
+	"shutdown":   Shutdown,
+	"restart":    Restart,
+	"ctrlaltdel": CtrlAltDel,
+}
+
+type TabEntry struct {
+	Id      string
+	Action  Action
+	Process string
+}
+
+var DefaultInittab = []TabEntry{
+	{"", SysInit, "/etc/init.d/rcS"},
+	{"", AskFirst, "/bin/sh"},
+	{"", CtrlAltDel, "/sbin/reboot"},
+	{"", Shutdown, "/sbin/swapoff -a"},
+	{"", Shutdown, "/bin/umount -a -r"},
+	{"", Restart, "/sbin/init"},
+	{"tty2", AskFirst, "/bin/sh"},
+	{"tty3", AskFirst, "/bin/sh"},
+	{"tty4", AskFirst, "/bin/sh"},
+}
+
+func ParseInittab(reader io.Reader) []TabEntry {
+	var res []TabEntry
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.HasPrefix(line, "#") {
+			continue
+		}
+
+		tokens := strings.Split(line, ":")
+		if len(tokens) != 4 {
+			continue
+		}
+
+		action, ok := ActionMap[tokens[2]]
+		if !ok {
+			continue
+		}
+
+		res = append(res, TabEntry{
+			Id:      tokens[0],
+			Action:  action,
+			Process: tokens[3],
+		})
+	}
+
+	return res
+}