hst/fs: interface filesystem config

This allows mount points to be represented by different underlying structs.

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

1 files changed, 102 insertions, 0 deletions

diff --git a/hst/fsbind.go b/hst/fsbind.go
new file mode 100644
index 00000000..e95eb7b7
--- /dev/null
+++ b/hst/fsbind.go
@@ -0,0 +1,102 @@
+package hst
+
+import (
+	"encoding/gob"
+	"strings"
+
+	"hakurei.app/container"
+)
+
+func init() { gob.Register(new(FSBind)) }
+
+// FilesystemBind is the [FilesystemConfig.Type] name of a bind mount point.
+const FilesystemBind = "bind"
+
+// FSBind represents a host to container bind mount.
+type FSBind struct {
+	// mount point in container, same as src if empty
+	Dst *container.Absolute `json:"dst,omitempty"`
+	// host filesystem path to make available to the container
+	Src *container.Absolute `json:"src"`
+	// do not mount filesystem read-only
+	Write bool `json:"write,omitempty"`
+	// do not disable device files, implies Write
+	Device bool `json:"dev,omitempty"`
+	// skip this mount point if the host path does not exist
+	Optional bool `json:"optional,omitempty"`
+}
+
+func (b *FSBind) Type() string { return FilesystemBind }
+
+func (b *FSBind) Target() *container.Absolute {
+	if b == nil || b.Src == nil {
+		return nil
+	}
+	if b.Dst == nil {
+		return b.Src
+	}
+	return b.Dst
+}
+
+func (b *FSBind) Host() []*container.Absolute {
+	if b == nil || b.Src == nil {
+		return nil
+	}
+	return []*container.Absolute{b.Src}
+}
+
+func (b *FSBind) Apply(ops *container.Ops) {
+	if b == nil || b.Src == nil {
+		return
+	}
+
+	dst := b.Dst
+	if dst == nil {
+		dst = b.Src
+	}
+	var flags int
+	if b.Write {
+		flags |= container.BindWritable
+	}
+	if b.Device {
+		flags |= container.BindDevice | container.BindWritable
+	}
+	if b.Optional {
+		flags |= container.BindOptional
+	}
+	ops.Bind(b.Src, dst, flags)
+}
+
+func (b *FSBind) String() string {
+	g := 4
+	if b == nil || b.Src == nil {
+		return "<invalid>"
+	}
+
+	g += len(b.Src.String())
+	if b.Dst != nil {
+		g += len(b.Dst.String())
+	}
+
+	expr := new(strings.Builder)
+	expr.Grow(g)
+
+	if b.Device {
+		expr.WriteString("d")
+	} else if b.Write {
+		expr.WriteString("w")
+	}
+
+	if !b.Optional {
+		expr.WriteString("*")
+	} else {
+		expr.WriteString("+")
+	}
+
+	expr.WriteString(b.Src.String())
+	if b.Dst != nil {
+		expr.WriteString(":" + b.Dst.String())
+	}
+
+	return expr.String()
+}