helper: separate helper args fd builder from dbus

This method of passing arguments is used in bubblewrap as well as other tools, this commit separates the argument builder/writer to the helper package and generalise it as an interface.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

1 files changed, 84 insertions, 0 deletions

diff --git a/dbus/dbus.go b/dbus/dbus.go
new file mode 100644
index 00000000..d0e82e17
--- /dev/null
+++ b/dbus/dbus.go
@@ -0,0 +1,84 @@
+package dbus
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"sync"
+
+	"git.ophivana.moe/cat/fortify/helper"
+)
+
+// Proxy holds references to a xdg-dbus-proxy process, and should never be copied.
+// Once sealed, configuration changes will no longer be possible and attempting to do so will result in a panic.
+type Proxy struct {
+	cmd *exec.Cmd
+
+	statP [2]*os.File
+	argsP [2]*os.File
+
+	path    string
+	session [2]string
+	system  [2]string
+
+	wait  *chan error
+	read  *chan error
+	ready *chan bool
+
+	seal helper.Args
+	lock sync.RWMutex
+}
+
+func (p *Proxy) String() string {
+	if p == nil {
+		return "(invalid dbus proxy)"
+	}
+
+	p.lock.RLock()
+	defer p.lock.RUnlock()
+
+	if p.cmd != nil {
+		return p.cmd.String()
+	}
+
+	if p.seal != nil {
+		return p.seal.String()
+	}
+
+	return "(unsealed dbus proxy)"
+}
+
+// Seal seals the Proxy instance.
+func (p *Proxy) Seal(session, system *Config) error {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	if p.seal != nil {
+		panic("dbus proxy sealed twice")
+	}
+
+	if session == nil && system == nil {
+		return errors.New("no configuration to seal")
+	}
+
+	seal := helper.NewArgs()
+
+	var args []string
+	if session != nil {
+		args = append(args, session.Args(p.session)...)
+	}
+	if system != nil {
+		args = append(args, system.Args(p.system)...)
+	}
+	if err := seal.Seal(args); err != nil {
+		return err
+	}
+
+	p.seal = seal
+	return nil
+}
+
+// New returns a reference to a new unsealed Proxy.
+func New(binPath string, session, system [2]string) *Proxy {
+	return &Proxy{path: binPath, session: session, system: system}
+}