1 files changed, 47 insertions, 0 deletions
diff --git a/container/inittmpfs.go b/container/inittmpfs.go
new file mode 100644
index 00000000..d4f03237
--- /dev/null
+++ b/container/inittmpfs.go
@@ -0,0 +1,47 @@
+package container
+
+import (
+	"encoding/gob"
+	"fmt"
+	"math"
+	"os"
+	. "syscall"
+)
+
+func init() { gob.Register(new(MountTmpfsOp)) }
+
+// Tmpfs appends an [Op] that mounts tmpfs on container path [MountTmpfsOp.Path].
+func (f *Ops) Tmpfs(target *Absolute, size int, perm os.FileMode) *Ops {
+	*f = append(*f, &MountTmpfsOp{SourceTmpfsEphemeral, target, MS_NOSUID | MS_NODEV, size, perm})
+	return f
+}
+
+// Readonly appends an [Op] that mounts read-only tmpfs on container path [MountTmpfsOp.Path].
+func (f *Ops) Readonly(target *Absolute, perm os.FileMode) *Ops {
+	*f = append(*f, &MountTmpfsOp{SourceTmpfsReadonly, target, MS_RDONLY | MS_NOSUID | MS_NODEV, 0, perm})
+	return f
+}
+
+// MountTmpfsOp mounts [FstypeTmpfs] on container Path.
+type MountTmpfsOp struct {
+	FSName string
+	Path   *Absolute
+	Flags  uintptr
+	Size   int
+	Perm   os.FileMode
+}
+
+func (t *MountTmpfsOp) early(*setupState) error { return nil }
+func (t *MountTmpfsOp) apply(*setupState) error {
+	if t.Path == nil {
+		return EBADE
+	}
+	if t.Size < 0 || t.Size > math.MaxUint>>1 {
+		return msg.WrapErr(EBADE, fmt.Sprintf("size %d out of bounds", t.Size))
+	}
+	return mountTmpfs(t.FSName, toSysroot(t.Path.String()), t.Flags, t.Size, t.Perm)
+}
+
+func (t *MountTmpfsOp) Is(op Op) bool  { vt, ok := op.(*MountTmpfsOp); return ok && *t == *vt }
+func (*MountTmpfsOp) prefix() string   { return "mounting" }
+func (t *MountTmpfsOp) String() string { return fmt.Sprintf("tmpfs on %q size %d", t.Path, t.Size) }