container/ops: merge mqueue and dev Ops

There is no reason to mount mqueue anywhere else, and these Ops usually follow each other. This change merges them. This helps decrease IPC overhead and also enables mounting dev readonly.

Signed-off-by: Ophestra <cat@gensokyo.uk>

1 files changed, 28 insertions, 42 deletions

diff --git a/container/ops.go b/container/ops.go
index b8d287fa..d64235fc 100644
--- a/container/ops.go
+++ b/container/ops.go
@@ -180,27 +180,29 @@ func (p MountProcOp) String() string { return fmt.Sprintf("proc on %q", string(p
 func init() { gob.Register(new(MountDevOp)) }
 
 // Dev appends an [Op] that mounts a subset of host /dev.
-func (f *Ops) Dev(dest string) *Ops {
-	*f = append(*f, MountDevOp(dest))
+func (f *Ops) Dev(dest string, mqueue bool) *Ops {
+	*f = append(*f, &MountDevOp{dest, mqueue})
 	return f
 }
 
-type MountDevOp string
+type MountDevOp struct {
+	Target string
+	Mqueue bool
+}
 
-func (d MountDevOp) early(*Params) error { return nil }
-func (d MountDevOp) apply(params *Params) error {
-	v := string(d)
-	if !path.IsAbs(v) {
-		return msg.WrapErr(EBADE, fmt.Sprintf("path %q is not absolute", v))
+func (d *MountDevOp) early(*Params) error { return nil }
+func (d *MountDevOp) apply(params *Params) error {
+	if !path.IsAbs(d.Target) {
+		return msg.WrapErr(EBADE, fmt.Sprintf("path %q is not absolute", d.Target))
 	}
-	target := toSysroot(v)
+	target := toSysroot(d.Target)
 
 	if err := mountTmpfs(SourceTmpfsDevtmpfs, target, MS_NOSUID|MS_NODEV, 0, params.ParentPerm); err != nil {
 		return err
 	}
 
 	for _, name := range []string{"null", "zero", "full", "random", "urandom", "tty"} {
-		targetPath := toSysroot(path.Join(v, name))
+		targetPath := path.Join(target, name)
 		if err := ensureFile(targetPath, 0444, params.ParentPerm); err != nil {
 			return err
 		}
@@ -247,7 +249,7 @@ func (d MountDevOp) apply(params *Params) error {
 	if params.RetainSession {
 		var buf [8]byte
 		if _, _, errno := Syscall(SYS_IOCTL, 1, TIOCGWINSZ, uintptr(unsafe.Pointer(&buf[0]))); errno == 0 {
-			consolePath := toSysroot(path.Join(v, "console"))
+			consolePath := path.Join(target, "console")
 			if err := ensureFile(consolePath, 0444, params.ParentPerm); err != nil {
 				return err
 			}
@@ -264,43 +266,27 @@ func (d MountDevOp) apply(params *Params) error {
 		}
 	}
 
-	return nil
-}
-
-func (d MountDevOp) Is(op Op) bool  { vd, ok := op.(MountDevOp); return ok && d == vd }
-func (MountDevOp) prefix() string   { return "mounting" }
-func (d MountDevOp) String() string { return fmt.Sprintf("dev on %q", string(d)) }
-
-func init() { gob.Register(new(MountMqueueOp)) }
+	if d.Mqueue {
+		mqueueTarget := path.Join(target, "mqueue")
+		if err := os.Mkdir(mqueueTarget, params.ParentPerm); err != nil {
+			return wrapErrSelf(err)
+		}
+		return wrapErrSuffix(Mount(SourceMqueue, mqueueTarget, FstypeMqueue, MS_NOSUID|MS_NOEXEC|MS_NODEV, zeroString),
+			"cannot mount mqueue:")
+	}
 
-// Mqueue appends an [Op] that mounts a private instance of mqueue.
-func (f *Ops) Mqueue(dest string) *Ops {
-	*f = append(*f, MountMqueueOp(dest))
-	return f
+	return nil
 }
 
-type MountMqueueOp string
-
-func (m MountMqueueOp) early(*Params) error { return nil }
-func (m MountMqueueOp) apply(params *Params) error {
-	v := string(m)
-
-	if !path.IsAbs(v) {
-		return msg.WrapErr(EBADE, fmt.Sprintf("path %q is not absolute", v))
-	}
-
-	target := toSysroot(v)
-	if err := os.MkdirAll(target, params.ParentPerm); err != nil {
-		return wrapErrSelf(err)
+func (d *MountDevOp) Is(op Op) bool { vd, ok := op.(*MountDevOp); return ok && *d == *vd }
+func (*MountDevOp) prefix() string  { return "mounting" }
+func (d *MountDevOp) String() string {
+	if d.Mqueue {
+		return fmt.Sprintf("dev on %q with mqueue", d.Target)
 	}
-	return wrapErrSuffix(Mount(SourceMqueue, target, FstypeMqueue, MS_NOSUID|MS_NOEXEC|MS_NODEV, zeroString),
-		fmt.Sprintf("cannot mount mqueue on %q:", v))
+	return fmt.Sprintf("dev on %q", d.Target)
 }
 
-func (m MountMqueueOp) Is(op Op) bool  { vm, ok := op.(MountMqueueOp); return ok && m == vm }
-func (MountMqueueOp) prefix() string   { return "mounting" }
-func (m MountMqueueOp) String() string { return fmt.Sprintf("mqueue on %q", string(m)) }
-
 func init() { gob.Register(new(MountTmpfsOp)) }
 
 // Tmpfs appends an [Op] that mounts tmpfs on container path [MountTmpfsOp.Path].