Revert "removed unused container child"

This reverts commit 30bc445a89.

internal/app/wwctl/container/exec/child/main.go

@@ -0,0 +1,90 @@
+//go:build linux
+// +build linux
+
+package child
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"syscall"
+
+	"github.com/hpcng/warewulf/internal/pkg/container"
+	"github.com/hpcng/warewulf/internal/pkg/util"
+	"github.com/hpcng/warewulf/internal/pkg/wwlog"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+)
+
+func CobraRunE(cmd *cobra.Command, args []string) error {
+	if os.Getpid() != 1 {
+		wwlog.Printf(wwlog.ERROR, "PID is not 1: %d\n", os.Getpid())
+		os.Exit(1)
+	}
+
+	containerName := args[0]
+
+	if !container.ValidSource(containerName) {
+		wwlog.Printf(wwlog.ERROR, "Unknown Warewulf container: %s\n", containerName)
+		os.Exit(1)
+	}
+
+	containerPath := container.RootFsDir(containerName)
+
+	err := syscall.Mount("", "/", "", syscall.MS_PRIVATE|syscall.MS_REC, "")
+	if err != nil {
+		return errors.Wrap(err, "failed to mount")
+	}
+
+	err = syscall.Mount("/dev", path.Join(containerPath, "/dev"), "", syscall.MS_BIND, "")
+	if err != nil {
+		return errors.Wrap(err, "failed to mount /dev")
+	}
+
+	for _, b := range binds {
+		var source string
+		var dest string
+
+		bind := util.SplitValidPaths(b, ":")
+		source = bind[0]
+
+		if len(bind) == 1 {
+			dest = source
+		} else {
+			dest = bind[1]
+		}
+
+		err := syscall.Mount(source, path.Join(containerPath, dest), "", syscall.MS_BIND, "")
+		if err != nil {
+			fmt.Printf("BIND ERROR: %s\n", err)
+			os.Exit(1)
+		}
+	}
+
+	err = syscall.Chroot(containerPath)
+	if err != nil {
+		return errors.Wrap(err, "failed to chroot")
+	}
+
+	err = os.Chdir("/")
+	if err != nil {
+		return errors.Wrap(err, "failed to chdir")
+	}
+
+	err = syscall.Mount("/proc", "/proc", "proc", 0, "")
+	if err != nil {
+		return errors.Wrap(err, "failed to mount proc")
+	}
+
+	os.Setenv("PS1", fmt.Sprintf("[%s] Warewulf> ", containerName))
+	os.Setenv("PATH", "/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin")
+	os.Setenv("HISTFILE", "/dev/null")
+
+	err = syscall.Exec(args[1], args[1:], os.Environ())
+	if err != nil {
+		wwlog.Printf(wwlog.ERROR, "%s\n", err)
+		os.Exit(1)
+	}
+
+	return nil
+}

internal/app/wwctl/container/exec/child/non-Linux.go

@@ -0,0 +1,15 @@
+//go:build !linux
+// +build !linux
+
+package child
+
+import (
+	"github.com/hpcng/warewulf/internal/pkg/wwlog"
+	"github.com/spf13/cobra"
+)
+
+func CobraRunE(cmd *cobra.Command, args []string) error {
+	wwlog.Printf(wwlog.ERROR, "This command does not work on non-Linux hosts\n")
+
+	return nil
+}

internal/app/wwctl/container/exec/child/root.go

@@ -0,0 +1,24 @@
+package child
+
+import "github.com/spf13/cobra"
+
+var (
+	baseCmd = &cobra.Command{
+		DisableFlagsInUseLine: true,
+		Use:                "__child",
+		Hidden:             true,
+		RunE:               CobraRunE,
+		Args:               cobra.MinimumNArgs(1),
+		FParseErrWhitelist: cobra.FParseErrWhitelist{UnknownFlags: true},
+	}
+	binds []string
+)
+
+func init() {
+	baseCmd.PersistentFlags().StringArrayVarP(&binds, "bind", "b", []string{}, "bind points")
+}
+
+// GetRootCommand returns the root cobra.Command for the application.
+func GetCommand() *cobra.Command {
+	return baseCmd
+}

internal/app/wwctl/container/exec/root.go

@@ -1,6 +1,7 @@
 package exec
 
 import (
+	"github.com/hpcng/warewulf/internal/app/wwctl/container/exec/child"
 	"github.com/hpcng/warewulf/internal/pkg/container"
 	"github.com/spf13/cobra"
 )
@@ -28,6 +29,7 @@ var (
 )
 
 func init() {
+	baseCmd.AddCommand(child.GetCommand())
 	baseCmd.PersistentFlags().StringArrayVarP(&binds, "bind", "b", []string{}, "Bind a local path into the container (must exist)")
 }