internal/pipewire: implement SecurityContext::Create

This is finally the thing we are after.

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

internal/pipewire/securitycontext.go

@@ -0,0 +1,69 @@
+package pipewire
+
+/* pipewire/extensions/security-context.h */
+
+const (
+	PW_TYPE_INTERFACE_SecurityContext = PW_TYPE_INFO_INTERFACE_BASE + "SecurityContext"
+	PW_SECURITY_CONTEXT_PERM_MASK     = PW_PERM_RWX
+	PW_VERSION_SECURITY_CONTEXT       = 3
+
+	PW_EXTENSION_MODULE_SECURITY_CONTEXT = PIPEWIRE_MODULE_PREFIX + "module-security-context"
+)
+
+const (
+	PW_SECURITY_CONTEXT_EVENT_NUM = iota
+
+	PW_VERSION_SECURITY_CONTEXT_EVENTS = 0
+)
+
+const (
+	PW_SECURITY_CONTEXT_METHOD_ADD_LISTENER = iota
+	PW_SECURITY_CONTEXT_METHOD_CREATE
+	PW_SECURITY_CONTEXT_METHOD_NUM
+
+	PW_VERSION_SECURITY_CONTEXT_METHODS = 0
+)
+
+// SecurityContextCreate is sent to create a new security context.
+//
+// Creates a new security context with a socket listening FD.
+// PipeWire will accept new client connections on listen_fd.
+//
+// listen_fd must be ready to accept new connections when this
+// request is sent by the client. In other words, the client must
+// call bind(2) and listen(2) before sending the FD.
+//
+// close_fd is a FD closed by the client when PipeWire should stop
+// accepting new connections on listen_fd.
+//
+// PipeWire must continue to accept connections on listen_fd when
+// the client which created the security context disconnects.
+//
+// After sending this request, closing listen_fd and close_fd
+// remains the only valid operation on them.
+type SecurityContextCreate struct {
+	// The offset in the SCM_RIGHTS msg_control message to
+	// the fd to listen on for new connections.
+	ListenFd Fd
+	// The offset in the SCM_RIGHTS msg_control message to
+	// the fd used to stop listening.
+	CloseFd Fd
+
+	// Extra properties. These will be copied on the client
+	// that connects through this context.
+	Properties *SPADict `json:"props"`
+}
+
+// Size satisfies [KnownSize] with a value computed at runtime.
+func (c *SecurityContextCreate) Size() Word {
+	return SizePrefix +
+		Size(SizeFd) +
+		Size(SizeFd) +
+		c.Properties.Size()
+}
+
+// MarshalBinary satisfies [encoding.BinaryMarshaler] via [Marshal].
+func (c *SecurityContextCreate) MarshalBinary() ([]byte, error) { return Marshal(c) }
+
+// UnmarshalBinary satisfies [encoding.BinaryUnmarshaler] via [Unmarshal].
+func (c *SecurityContextCreate) UnmarshalBinary(data []byte) error { return Unmarshal(data, c) }