system: move system access packages

These packages loosely belong in the "system" package and "system" provides high level wrappers for all of them.

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

1 files changed, 117 insertions, 0 deletions

diff --git a/system/dbus/proxy.go b/system/dbus/proxy.go
new file mode 100644
index 00000000..cc0af1ea
--- /dev/null
+++ b/system/dbus/proxy.go
@@ -0,0 +1,117 @@
+package dbus
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os/exec"
+	"sync"
+	"syscall"
+
+	"git.gensokyo.uk/security/hakurei/helper"
+)
+
+// ProxyName is the file name or path to the proxy program.
+// Overriding ProxyName will only affect Proxy instance created after the change.
+var ProxyName = "xdg-dbus-proxy"
+
+type BadInterfaceError struct {
+	Interface string
+	Segment   string
+}
+
+func (e *BadInterfaceError) Error() string {
+	return fmt.Sprintf("bad interface string %q in %s bus configuration", e.Interface, e.Segment)
+}
+
+// Proxy holds the state of a xdg-dbus-proxy process, and should never be copied.
+type Proxy struct {
+	helper helper.Helper
+	ctx    context.Context
+
+	cancel context.CancelCauseFunc
+	cause  func() error
+
+	final      *Final
+	output     io.Writer
+	useSandbox bool
+
+	name string
+	CmdF func(any)
+
+	CommandContext func(ctx context.Context) (cmd *exec.Cmd)
+	FilterF        func([]byte) []byte
+
+	mu, pmu sync.RWMutex
+}
+
+func (p *Proxy) String() string {
+	if p == nil {
+		return "(invalid dbus proxy)"
+	}
+
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+
+	if p.helper != nil {
+		return p.helper.String()
+	}
+
+	return "(unused dbus proxy)"
+}
+
+// Final describes the outcome of a proxy configuration.
+type Final struct {
+	Session, System ProxyPair
+	// parsed upstream address
+	SessionUpstream, SystemUpstream []AddrEntry
+	io.WriterTo
+}
+
+// Finalise creates a checked argument writer for [Proxy].
+func Finalise(sessionBus, systemBus ProxyPair, session, system *Config) (final *Final, err error) {
+	if session == nil && system == nil {
+		return nil, syscall.EBADE
+	}
+
+	var args []string
+	if session != nil {
+		if err = session.checkInterfaces("session"); err != nil {
+			return
+		}
+		args = append(args, session.Args(sessionBus)...)
+	}
+	if system != nil {
+		if err = system.checkInterfaces("system"); err != nil {
+			return
+		}
+		args = append(args, system.Args(systemBus)...)
+	}
+
+	final = &Final{Session: sessionBus, System: systemBus}
+
+	final.WriterTo, err = helper.NewCheckedArgs(args)
+	if err != nil {
+		return
+	}
+
+	if session != nil {
+		final.SessionUpstream, err = Parse([]byte(final.Session[0]))
+		if err != nil {
+			return
+		}
+	}
+	if system != nil {
+		final.SystemUpstream, err = Parse([]byte(final.System[0]))
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}
+
+// New returns a new instance of [Proxy].
+func New(ctx context.Context, final *Final, output io.Writer) *Proxy {
+	return &Proxy{name: ProxyName, ctx: ctx, final: final, output: output, useSandbox: true}
+}