internal: relocate packages

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

internal/dbus/address.go

@@ -0,0 +1,193 @@
+package dbus
+
+import (
+	"bytes"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"slices"
+)
+
+type AddrEntry struct {
+	Method string      `json:"method"`
+	Values [][2]string `json:"values"`
+}
+
+// EqualAddrEntries returns whether two slices of [AddrEntry] are equal.
+func EqualAddrEntries(entries, target []AddrEntry) bool {
+	return slices.EqualFunc(entries, target, func(a AddrEntry, b AddrEntry) bool {
+		return a.Method == b.Method && slices.Equal(a.Values, b.Values)
+	})
+}
+
+// Parse parses D-Bus address according to
+// https://dbus.freedesktop.org/doc/dbus-specification.html#addresses
+func Parse(addr []byte) ([]AddrEntry, error) {
+	// Look for a semicolon
+	address := bytes.Split(bytes.TrimSuffix(addr, []byte{';'}), []byte{';'})
+
+	// Allocate for entries
+	v := make([]AddrEntry, len(address))
+
+	for i, s := range address {
+		var pairs [][]byte
+
+		// Look for the colon :
+		if method, list, ok := bytes.Cut(s, []byte{':'}); !ok {
+			return v, &BadAddressError{ErrNoColon, i, s, -1, nil}
+		} else {
+			pairs = bytes.Split(list, []byte{','})
+			v[i].Method = string(method)
+			v[i].Values = make([][2]string, len(pairs))
+		}
+
+		for j, pair := range pairs {
+			key, value, ok := bytes.Cut(pair, []byte{'='})
+			if !ok {
+				return v, &BadAddressError{ErrBadPairSep, i, s, j, pair}
+			}
+			if len(key) == 0 {
+				return v, &BadAddressError{ErrBadPairKey, i, s, j, pair}
+			}
+			if len(value) == 0 {
+				return v, &BadAddressError{ErrBadPairVal, i, s, j, pair}
+			}
+			v[i].Values[j][0] = string(key)
+
+			if val, errno := unescapeValue(value); errno != errSuccess {
+				return v, &BadAddressError{errno, i, s, j, pair}
+			} else {
+				v[i].Values[j][1] = string(val)
+			}
+		}
+	}
+
+	return v, nil
+}
+
+func unescapeValue(v []byte) (val []byte, errno ParseError) {
+	if l := len(v) - (bytes.Count(v, []byte{'%'}) * 2); l < 0 {
+		errno = ErrBadValLength
+		return
+	} else {
+		val = make([]byte, l)
+	}
+
+	var i, skip int
+	for iu, b := range v {
+		if skip > 0 {
+			skip--
+			continue
+		}
+
+		if ib := bytes.IndexByte([]byte("-_/.\\*"), b); ib != -1 { // - // _/.\*
+			goto opt
+		} else if b >= '0' && b <= '9' { // 0-9
+			goto opt
+		} else if b >= 'A' && b <= 'Z' { // A-Z
+			goto opt
+		} else if b >= 'a' && b <= 'z' { // a-z
+			goto opt
+		}
+
+		if b != '%' {
+			errno = ErrBadValByte
+			break
+		}
+
+		skip += 2
+		if iu+2 >= len(v) {
+			errno = ErrBadValHexLength
+			break
+		}
+		if c, err := hex.Decode(val[i:i+1], v[iu+1:iu+3]); err != nil {
+			if errors.As(err, new(hex.InvalidByteError)) {
+				errno = ErrBadValHexByte
+				break
+			}
+			// unreachable
+			panic(err.Error())
+		} else if c != 1 {
+			// unreachable
+			panic(fmt.Sprintf("invalid decode length %d", c))
+		}
+		i++
+		continue
+
+	opt:
+		val[i] = b
+		i++
+	}
+
+	return
+}
+
+type ParseError uint8
+
+func (e ParseError) Error() string {
+	switch e {
+	case errSuccess:
+		panic("attempted to return success as error")
+	case ErrNoColon:
+		return "address does not contain a colon"
+	case ErrBadPairSep:
+		return "'=' character not found"
+	case ErrBadPairKey:
+		return "'=' character has no key preceding it"
+	case ErrBadPairVal:
+		return "'=' character has no value following it"
+	case ErrBadValLength:
+		return "unescaped value has impossible length"
+	case ErrBadValByte:
+		return "in D-Bus address, characters other than [-0-9A-Za-z_/.\\*] should have been escaped"
+	case ErrBadValHexLength:
+		return "in D-Bus address, percent character was not followed by two hex digits"
+	case ErrBadValHexByte:
+		return "in D-Bus address, percent character was followed by characters other than hex digits"
+
+	default:
+		return fmt.Sprintf("parse error %d", e)
+	}
+}
+
+const (
+	errSuccess ParseError = iota
+	ErrNoColon
+	ErrBadPairSep
+	ErrBadPairKey
+	ErrBadPairVal
+	ErrBadValLength
+	ErrBadValByte
+	ErrBadValHexLength
+	ErrBadValHexByte
+)
+
+type BadAddressError struct {
+	// error type
+	Type ParseError
+
+	// bad entry position
+	EntryPos int
+	// bad entry value
+	EntryVal []byte
+
+	// bad pair position
+	PairPos int
+	// bad pair value
+	PairVal []byte
+}
+
+func (a *BadAddressError) Is(err error) bool {
+	var b *BadAddressError
+	return errors.As(err, &b) && a.Type == b.Type &&
+		a.EntryPos == b.EntryPos && slices.Equal(a.EntryVal, b.EntryVal) &&
+		a.PairPos == b.PairPos && slices.Equal(a.PairVal, b.PairVal)
+}
+
+func (a *BadAddressError) Error() string {
+	return a.Type.Error()
+}
+
+func (a *BadAddressError) Unwrap() error {
+	return a.Type
+}

internal/dbus/address_escape_test.go

@@ -0,0 +1,59 @@
+package dbus
+
+import (
+	"testing"
+)
+
+func TestUnescapeValue(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		value   string
+		want    string
+		wantErr ParseError
+	}{
+		// upstream test cases
+		{value: "abcde", want: "abcde"},
+		{value: "", want: ""},
+		{value: "%20%20", want: "  "},
+		{value: "%24", want: "$"},
+		{value: "%25", want: "%"},
+		{value: "abc%24", want: "abc$"},
+		{value: "%24abc", want: "$abc"},
+		{value: "abc%24abc", want: "abc$abc"},
+		{value: "/", want: "/"},
+		{value: "-", want: "-"},
+		{value: "_", want: "_"},
+		{value: "A", want: "A"},
+		{value: "I", want: "I"},
+		{value: "Z", want: "Z"},
+		{value: "a", want: "a"},
+		{value: "i", want: "i"},
+		{value: "z", want: "z"},
+		/* Bug: https://bugs.freedesktop.org/show_bug.cgi?id=53499 */
+		{value: "%c3%b6", want: "\xc3\xb6"},
+
+		{value: "%a", wantErr: ErrBadValHexLength},
+		{value: "%q", wantErr: ErrBadValHexLength},
+		{value: "%az", wantErr: ErrBadValHexByte},
+		{value: "%%", wantErr: ErrBadValLength},
+		{value: "%$$", wantErr: ErrBadValHexByte},
+		{value: "abc%a", wantErr: ErrBadValHexLength},
+		{value: "%axyz", wantErr: ErrBadValHexByte},
+		{value: "%", wantErr: ErrBadValLength},
+		{value: "$", wantErr: ErrBadValByte},
+		{value: " ", wantErr: ErrBadValByte},
+	}
+
+	for _, tc := range testCases {
+		t.Run("unescape "+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			if got, errno := unescapeValue([]byte(tc.value)); errno != tc.wantErr {
+				t.Errorf("unescapeValue() errno = %v, wantErr %v", errno, tc.wantErr)
+			} else if tc.wantErr == errSuccess && string(got) != tc.want {
+				t.Errorf("unescapeValue() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}

internal/dbus/address_test.go

@@ -0,0 +1,123 @@
+package dbus_test
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"hakurei.app/internal/dbus"
+)
+
+func TestParse(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name    string
+		addr    string
+		want    []dbus.AddrEntry
+		wantErr error
+	}{
+		{
+			name: "simple session unix",
+			addr: "unix:path=/run/user/1971/bus",
+			want: []dbus.AddrEntry{{
+				Method: "unix",
+				Values: [][2]string{{"path", "/run/user/1971/bus"}},
+			}},
+		},
+		{
+			name: "simple upper escape",
+			addr: "debug:name=Test,cat=cute,escaped=%c3%b6",
+			want: []dbus.AddrEntry{{
+				Method: "debug",
+				Values: [][2]string{
+					{"name", "Test"},
+					{"cat", "cute"},
+					{"escaped", "\xc3\xb6"},
+				},
+			}},
+		},
+		{
+			name: "simple bad escape",
+			addr: "debug:name=%",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadValLength,
+				EntryPos: 0, EntryVal: []byte("debug:name=%"), PairPos: 0, PairVal: []byte("name=%")},
+		},
+
+		// upstream test cases
+		{
+			name: "full address success",
+			addr: "unix:path=/tmp/foo;debug:name=test,sliff=sloff;",
+			want: []dbus.AddrEntry{
+				{Method: "unix", Values: [][2]string{{"path", "/tmp/foo"}}},
+				{Method: "debug", Values: [][2]string{{"name", "test"}, {"sliff", "sloff"}}},
+			},
+		},
+		{
+			name: "empty address",
+			addr: "",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrNoColon,
+				EntryVal: []byte{}, PairPos: -1},
+		},
+		{
+			name: "no body",
+			addr: "foo",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrNoColon,
+				EntryPos: 0, EntryVal: []byte("foo"), PairPos: -1},
+		},
+		{
+			name: "no pair separator",
+			addr: "foo:bar",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:bar"), PairPos: 0, PairVal: []byte("bar")},
+		},
+		{
+			name: "no pair separator multi pair",
+			addr: "foo:bar,baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:bar,baz"), PairPos: 0, PairVal: []byte("bar")},
+		},
+		{
+			name: "no pair separator single valid pair",
+			addr: "foo:bar=foo,baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:bar=foo,baz"), PairPos: 1, PairVal: []byte("baz")},
+		},
+		{
+			name: "no body single valid address",
+			addr: "foo:bar=foo;baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrNoColon,
+				EntryPos: 1, EntryVal: []byte("baz"), PairPos: -1},
+		},
+		{
+			name: "no key",
+			addr: "foo:=foo",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairKey,
+				EntryPos: 0, EntryVal: []byte("foo:=foo"), PairPos: 0, PairVal: []byte("=foo")},
+		},
+		{
+			name: "no value",
+			addr: "foo:foo=",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairVal,
+				EntryPos: 0, EntryVal: []byte("foo:foo="), PairPos: 0, PairVal: []byte("foo=")},
+		},
+		{
+			name: "no pair separator single valid pair trailing",
+			addr: "foo:foo,bar=baz",
+			wantErr: &dbus.BadAddressError{Type: dbus.ErrBadPairSep,
+				EntryPos: 0, EntryVal: []byte("foo:foo,bar=baz"), PairPos: 0, PairVal: []byte("foo")},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			if got, err := dbus.Parse([]byte(tc.addr)); !errors.Is(err, tc.wantErr) {
+				t.Errorf("Parse() error = %v, wantErr %v", err, tc.wantErr)
+			} else if tc.wantErr == nil && !reflect.DeepEqual(got, tc.want) {
+				t.Errorf("Parse() = %#v, want %#v", got, tc.want)
+			}
+		})
+	}
+}

internal/dbus/config.go

@@ -0,0 +1,71 @@
+package dbus
+
+import (
+	"hakurei.app/hst"
+)
+
+// ProxyPair is an upstream dbus address and a downstream socket path.
+type ProxyPair [2]string
+
+// Args returns the xdg-dbus-proxy arguments equivalent of [hst.BusConfig].
+func Args(c *hst.BusConfig, bus ProxyPair) (args []string) {
+	argc := 2 + len(c.See) + len(c.Talk) + len(c.Own) + len(c.Call) + len(c.Broadcast)
+	if c.Log {
+		argc++
+	}
+	if c.Filter {
+		argc++
+	}
+
+	args = make([]string, 0, argc)
+	args = append(args, bus[0], bus[1])
+	if c.Filter {
+		args = append(args, "--filter")
+	}
+	for _, name := range c.See {
+		args = append(args, "--see="+name)
+	}
+	for _, name := range c.Talk {
+		args = append(args, "--talk="+name)
+	}
+	for _, name := range c.Own {
+		args = append(args, "--own="+name)
+	}
+	for name, rule := range c.Call {
+		args = append(args, "--call="+name+"="+rule)
+	}
+	for name, rule := range c.Broadcast {
+		args = append(args, "--broadcast="+name+"="+rule)
+	}
+	if c.Log {
+		args = append(args, "--log")
+	}
+
+	return
+}
+
+// NewConfig returns the address of a new [hst.BusConfig] with optional defaults.
+func NewConfig(id string, defaults, mpris bool) *hst.BusConfig {
+	c := hst.BusConfig{
+		Call:      make(map[string]string),
+		Broadcast: make(map[string]string),
+
+		Filter: true,
+	}
+
+	if defaults {
+		c.Talk = []string{"org.freedesktop.DBus", "org.freedesktop.Notifications"}
+
+		c.Call["org.freedesktop.portal.*"] = "*"
+		c.Broadcast["org.freedesktop.portal.*"] = "@/org/freedesktop/portal/*"
+
+		if id != "" {
+			c.Own = []string{id + ".*"}
+			if mpris {
+				c.Own = append(c.Own, "org.mpris.MediaPlayer2."+id+".*")
+			}
+		}
+	}
+
+	return &c
+}

internal/dbus/config_test.go

@@ -0,0 +1,124 @@
+package dbus_test
+
+import (
+	"reflect"
+	"slices"
+	"strings"
+	"testing"
+
+	"hakurei.app/hst"
+	"hakurei.app/internal/dbus"
+)
+
+func TestConfigArgs(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range testCasesExt {
+		if tc.wantErr {
+			// args does not check for nulls
+			continue
+		}
+
+		t.Run("build arguments for "+tc.id, func(t *testing.T) {
+			t.Parallel()
+
+			if got := dbus.Args(tc.c, tc.bus); !slices.Equal(got, tc.want) {
+				t.Errorf("Args: %v, want %v", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestNewConfig(t *testing.T) {
+	t.Parallel()
+	ids := [...]string{"org.chromium.Chromium", "dev.vencord.Vesktop"}
+
+	type newTestCase struct {
+		id   string
+		args [2]bool
+		want *hst.BusConfig
+	}
+
+	// populate tests from IDs in generic tests
+	tcs := make([]newTestCase, 0, (len(ids)+1)*4)
+	// tests for defaults without id
+	tcs = append(tcs,
+		newTestCase{"", [2]bool{false, false}, &hst.BusConfig{
+			Call:      make(map[string]string),
+			Broadcast: make(map[string]string),
+			Filter:    true,
+		}},
+		newTestCase{"", [2]bool{false, true}, &hst.BusConfig{
+			Call:      make(map[string]string),
+			Broadcast: make(map[string]string),
+			Filter:    true,
+		}},
+		newTestCase{"", [2]bool{true, false}, &hst.BusConfig{
+			Talk:      []string{"org.freedesktop.DBus", "org.freedesktop.Notifications"},
+			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+			Filter:    true,
+		}},
+		newTestCase{"", [2]bool{true, true}, &hst.BusConfig{
+			Talk:      []string{"org.freedesktop.DBus", "org.freedesktop.Notifications"},
+			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+			Filter:    true,
+		}},
+	)
+	for _, id := range ids {
+		tcs = append(tcs,
+			newTestCase{id, [2]bool{false, false}, &hst.BusConfig{
+				Call:      make(map[string]string),
+				Broadcast: make(map[string]string),
+				Filter:    true,
+			}},
+			newTestCase{id, [2]bool{false, true}, &hst.BusConfig{
+				Call:      make(map[string]string),
+				Broadcast: make(map[string]string),
+				Filter:    true,
+			}},
+			newTestCase{id, [2]bool{true, false}, &hst.BusConfig{
+				Talk:      []string{"org.freedesktop.DBus", "org.freedesktop.Notifications"},
+				Own:       []string{id + ".*"},
+				Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+				Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+				Filter:    true,
+			}},
+			newTestCase{id, [2]bool{true, true}, &hst.BusConfig{
+				Talk:      []string{"org.freedesktop.DBus", "org.freedesktop.Notifications"},
+				Own:       []string{id + ".*", "org.mpris.MediaPlayer2." + id + ".*"},
+				Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+				Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+				Filter:    true,
+			}},
+		)
+	}
+
+	for _, tc := range tcs {
+		name := new(strings.Builder)
+		name.WriteString("create new configuration struct")
+
+		if tc.args[0] {
+			name.WriteString(" with builtin defaults")
+			if tc.args[1] {
+				name.WriteString(" (mpris)")
+			}
+		}
+
+		if tc.id != "" {
+			name.WriteString(" for application ID ")
+			name.WriteString(tc.id)
+		}
+
+		t.Run(name.String(), func(t *testing.T) {
+			t.Parallel()
+
+			if gotC := dbus.NewConfig(tc.id, tc.args[0], tc.args[1]); !reflect.DeepEqual(gotC, tc.want) {
+				t.Errorf("NewConfig(%q, %t, %t) = %v, want %v",
+					tc.id, tc.args[0], tc.args[1],
+					gotC, tc.want)
+			}
+		})
+	}
+}

internal/dbus/dbus.go

@@ -0,0 +1,69 @@
+// Package dbus wraps xdg-dbus-proxy and implements configuration and sandboxing of the underlying helper process.
+package dbus
+
+import (
+	"fmt"
+	"os"
+	"sync"
+)
+
+const (
+	/*
+		SessionBusAddress is the name of the environment variable where the address of the login session message bus is given in.
+
+		If that variable is not set, applications may also try to read the address from the X Window System root window property _DBUS_SESSION_BUS_ADDRESS.
+		The root window property must have type STRING. The environment variable should have precedence over the root window property.
+
+		The address of the login session message bus is given in the DBUS_SESSION_BUS_ADDRESS environment variable.
+		If DBUS_SESSION_BUS_ADDRESS is not set, or if it's set to the string "autolaunch:",
+		the system should use platform-specific methods of locating a running D-Bus session server,
+		or starting one if a running instance cannot be found.
+		Note that this mechanism is not recommended for attempting to determine if a daemon is running.
+		It is inherently racy to attempt to make this determination, since the bus daemon may be started just before or just after the determination is made.
+		Therefore, it is recommended that applications do not try to make this determination for their functionality purposes, and instead they should attempt to start the server.
+
+		This package diverges from the specification, as the caller is unlikely to be an X client, or be in a position to autolaunch a dbus server.
+		So a fallback address with a socket located in the well-known default XDG_RUNTIME_DIR formatting is used.
+	*/
+	SessionBusAddress = "DBUS_SESSION_BUS_ADDRESS"
+
+	/*
+		SystemBusAddress is the name of the environment variable where the address of the system message bus is given in.
+
+		If that variable is not set, applications should try to connect to the well-known address unix:path=/var/run/dbus/system_bus_socket.
+		Implementations of the well-known system bus should listen on an address that will result in that connection being successful.
+	*/
+	SystemBusAddress = "DBUS_SYSTEM_BUS_ADDRESS"
+
+	// FallbackSystemBusAddress is used when [SystemBusAddress] is not set.
+	FallbackSystemBusAddress = "unix:path=/var/run/dbus/system_bus_socket"
+)
+
+var (
+	address     [2]string
+	addressOnce sync.Once
+)
+
+// Address returns the session and system bus addresses copied from environment,
+// or appropriate fallback values if they are not set.
+func Address() (session, system string) {
+	addressOnce.Do(func() {
+		// resolve upstream session bus address
+		if addr, ok := os.LookupEnv(SessionBusAddress); !ok {
+			// fall back to default format
+			address[0] = fmt.Sprintf("unix:path=/run/user/%d/bus", os.Getuid())
+		} else {
+			address[0] = addr
+		}
+
+		// resolve upstream system bus address
+		if addr, ok := os.LookupEnv(SystemBusAddress); !ok {
+			// fall back to default hardcoded value
+			address[1] = FallbackSystemBusAddress
+		} else {
+			address[1] = addr
+		}
+	})
+
+	return address[0], address[1]
+}

internal/dbus/dbus_test.go

@@ -0,0 +1,170 @@
+package dbus_test
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"syscall"
+	"testing"
+	"time"
+
+	"hakurei.app/internal/dbus"
+	"hakurei.app/internal/helper"
+	"hakurei.app/message"
+)
+
+func TestFinalise(t *testing.T) {
+	if _, err := dbus.Finalise(dbus.ProxyPair{}, dbus.ProxyPair{}, nil, nil); !errors.Is(err, syscall.EBADE) {
+		t.Errorf("Finalise: error = %v, want %v",
+			err, syscall.EBADE)
+	}
+
+	for id, tc := range testCasePairs {
+		t.Run("create final for "+id, func(t *testing.T) {
+			var wt io.WriterTo
+			if v, err := dbus.Finalise(tc[0].bus, tc[1].bus, tc[0].c, tc[1].c); (errors.Is(err, syscall.EINVAL)) != tc[0].wantErr {
+				t.Errorf("Finalise: error = %v, wantErr %v",
+					err, tc[0].wantErr)
+				return
+			} else {
+				wt = v
+			}
+
+			// rest of the tests happen for sealed instances
+			if tc[0].wantErr {
+				return
+			}
+
+			// build null-terminated string from wanted args
+			want := new(strings.Builder)
+			args := append(tc[0].want, tc[1].want...)
+			for _, arg := range args {
+				want.WriteString(arg)
+				want.WriteByte(0)
+			}
+
+			got := new(strings.Builder)
+			if _, err := wt.WriteTo(got); err != nil {
+				t.Errorf("WriteTo: error = %v", err)
+			}
+
+			if want.String() != got.String() {
+				t.Errorf("Seal: %q, want %q",
+					got.String(), want.String())
+			}
+		})
+	}
+}
+
+func TestProxyStartWaitCloseString(t *testing.T) {
+	t.Run("sandbox", func(t *testing.T) { testProxyFinaliseStartWaitCloseString(t, true) })
+	t.Run("direct", func(t *testing.T) { testProxyFinaliseStartWaitCloseString(t, false) })
+}
+
+const (
+	stubProxyTimeout = 5 * time.Second
+)
+
+func testProxyFinaliseStartWaitCloseString(t *testing.T, useSandbox bool) {
+	{
+		oldWaitDelay := helper.WaitDelay
+		helper.WaitDelay = 16 * time.Second
+		t.Cleanup(func() { helper.WaitDelay = oldWaitDelay })
+	}
+
+	{
+		proxyName := dbus.ProxyName
+		dbus.ProxyName = os.Args[0]
+		t.Cleanup(func() { dbus.ProxyName = proxyName })
+	}
+
+	var p *dbus.Proxy
+
+	t.Run("string for nil proxy", func(t *testing.T) {
+		want := "(invalid dbus proxy)"
+		if got := p.String(); got != want {
+			t.Errorf("String: %q, want %q",
+				got, want)
+		}
+	})
+
+	t.Run("invalid start", func(t *testing.T) {
+		if !useSandbox {
+			p = dbus.NewDirect(t.Context(), message.New(nil), nil, nil)
+		} else {
+			p = dbus.New(t.Context(), message.New(nil), nil, nil)
+		}
+
+		if err := p.Start(); !errors.Is(err, syscall.ENOTRECOVERABLE) {
+			t.Errorf("Start: error = %q, wantErr %q", err, syscall.ENOTRECOVERABLE)
+			return
+		}
+	})
+
+	for id, tc := range testCasePairs {
+		// this test does not test errors
+		if tc[0].wantErr {
+			continue
+		}
+
+		t.Run("proxy for "+id, func(t *testing.T) {
+			var final *dbus.Final
+			t.Run("finalise", func(t *testing.T) {
+				if v, err := dbus.Finalise(tc[0].bus, tc[1].bus, tc[0].c, tc[1].c); err != nil {
+					t.Errorf("Finalise: error = %v, wantErr %v", err, tc[0].wantErr)
+					return
+				} else {
+					final = v
+				}
+			})
+
+			ctx, cancel := context.WithTimeout(t.Context(), stubProxyTimeout)
+			defer cancel()
+			output := new(strings.Builder)
+			if !useSandbox {
+				p = dbus.NewDirect(ctx, message.New(nil), final, output)
+			} else {
+				p = dbus.New(ctx, message.New(nil), final, output)
+			}
+
+			{ // check invalid wait behaviour
+				wantErr := "dbus: not started"
+				if err := p.Wait(); err == nil || err.Error() != wantErr {
+					t.Errorf("Wait: error = %v, wantErr %v", err, wantErr)
+				}
+			}
+
+			{ // check string behaviour
+				want := "(unused dbus proxy)"
+				if got := p.String(); got != want {
+					t.Errorf("String: %q, want %q", got, want)
+					return
+				}
+			}
+
+			if err := p.Start(); err != nil {
+				t.Fatalf("Start: error = %v", err)
+			}
+
+			{ // check running string behaviour
+				wantSubstr := fmt.Sprintf("%s --args=3 --fd=4", os.Args[0])
+				if useSandbox {
+					wantSubstr = `argv: ["xdg-dbus-proxy" "--args=3" "--fd=4"], filter: true, rules: 0, flags: 0x1, presets: 0xf`
+				}
+				if got := p.String(); !strings.Contains(got, wantSubstr) {
+					t.Errorf("String: %q, want %q",
+						got, wantSubstr)
+					return
+				}
+			}
+
+			p.Close()
+			if err := p.Wait(); err != nil {
+				t.Errorf("Wait: error = %v\noutput: %s", err, output.String())
+			}
+		})
+	}
+}

internal/dbus/export_test.go

@@ -0,0 +1,15 @@
+package dbus
+
+import (
+	"context"
+	"io"
+
+	"hakurei.app/message"
+)
+
+// NewDirect returns a new instance of [Proxy] with its sandbox disabled.
+func NewDirect(ctx context.Context, msg message.Msg, final *Final, output io.Writer) *Proxy {
+	p := New(ctx, msg, final, output)
+	p.useSandbox = false
+	return p
+}

internal/dbus/proc.go

@@ -0,0 +1,188 @@
+package dbus
+
+import (
+	"context"
+	"errors"
+	"os"
+	"os/exec"
+	"strconv"
+	"syscall"
+
+	"hakurei.app/container"
+	"hakurei.app/container/check"
+	"hakurei.app/container/seccomp"
+	"hakurei.app/container/std"
+	"hakurei.app/internal/helper"
+	"hakurei.app/ldd"
+)
+
+// Start starts and configures a D-Bus proxy process.
+func (p *Proxy) Start() error {
+	if p.final == nil || p.final.WriterTo == nil {
+		return syscall.ENOTRECOVERABLE
+	}
+
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.pmu.Lock()
+	defer p.pmu.Unlock()
+
+	if p.cancel != nil || p.cause != nil {
+		return errors.New("dbus: already started")
+	}
+
+	ctx, cancel := context.WithCancelCause(p.ctx)
+
+	if !p.useSandbox {
+		p.helper = helper.NewDirect(ctx, p.name, p.final, true, argF, func(cmd *exec.Cmd) {
+			if p.output != nil {
+				cmd.Stdout, cmd.Stderr = p.output, p.output
+			}
+			cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+			cmd.Env = make([]string, 0)
+		}, nil)
+	} else {
+		var toolPath *check.Absolute
+		if a, err := check.NewAbs(p.name); err != nil {
+			if p.name, err = exec.LookPath(p.name); err != nil {
+				return err
+			} else if toolPath, err = check.NewAbs(p.name); err != nil {
+				return err
+			}
+		} else {
+			toolPath = a
+		}
+
+		var libPaths []*check.Absolute
+		if entries, err := ldd.Resolve(ctx, p.msg, toolPath); err != nil {
+			return err
+		} else {
+			libPaths = ldd.Path(entries)
+		}
+
+		p.helper = helper.New(
+			ctx, p.msg, toolPath, "xdg-dbus-proxy",
+			p.final, true,
+			argF, func(z *container.Container) {
+				z.SeccompFlags |= seccomp.AllowMultiarch
+				z.SeccompPresets |= std.PresetStrict
+				z.Hostname = "hakurei-dbus"
+				if p.output != nil {
+					z.Stdout, z.Stderr = p.output, p.output
+				}
+
+				// these lib paths are unpredictable, so mount them first so they cannot cover anything
+				for _, name := range libPaths {
+					z.Bind(name, name, 0)
+				}
+
+				// upstream bus directories
+				upstreamPaths := make([]*check.Absolute, 0, 2)
+				for _, addr := range [][]AddrEntry{p.final.SessionUpstream, p.final.SystemUpstream} {
+					for _, ent := range addr {
+						if ent.Method != "unix" {
+							continue
+						}
+						for _, pair := range ent.Values {
+							if pair[0] != "path" {
+								continue
+							}
+							if a, err := check.NewAbs(pair[1]); err != nil {
+								continue
+							} else {
+								upstreamPaths = append(upstreamPaths, a.Dir())
+							}
+						}
+					}
+				}
+				check.SortAbs(upstreamPaths)
+				upstreamPaths = check.CompactAbs(upstreamPaths)
+				for _, name := range upstreamPaths {
+					z.Bind(name, name, 0)
+				}
+				z.HostNet = len(upstreamPaths) == 0
+				z.HostAbstract = z.HostNet
+
+				// parent directories of bind paths
+				sockDirPaths := make([]*check.Absolute, 0, 2)
+				if a, err := check.NewAbs(p.final.Session[1]); err == nil {
+					sockDirPaths = append(sockDirPaths, a.Dir())
+				}
+				if a, err := check.NewAbs(p.final.System[1]); err == nil {
+					sockDirPaths = append(sockDirPaths, a.Dir())
+				}
+				check.SortAbs(sockDirPaths)
+				sockDirPaths = check.CompactAbs(sockDirPaths)
+				for _, name := range sockDirPaths {
+					z.Bind(name, name, std.BindWritable)
+				}
+
+				// xdg-dbus-proxy bin path
+				binPath := toolPath.Dir()
+				z.Bind(binPath, binPath, 0)
+			}, nil)
+	}
+
+	if err := p.helper.Start(); err != nil {
+		cancel(err)
+		p.helper = nil
+		return err
+	}
+
+	p.cancel, p.cause = cancel, func() error { return context.Cause(ctx) }
+	return nil
+}
+
+var proxyClosed = errors.New("proxy closed")
+
+// Wait blocks until xdg-dbus-proxy exits and releases resources.
+func (p *Proxy) Wait() error {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+
+	p.pmu.RLock()
+	if p.helper == nil || p.cancel == nil || p.cause == nil {
+		p.pmu.RUnlock()
+		return errors.New("dbus: not started")
+	}
+
+	var errs [3]error
+
+	errs[0] = p.helper.Wait()
+	if errors.Is(errs[0], context.Canceled) &&
+		errors.Is(p.cause(), proxyClosed) {
+		errs[0] = nil
+	}
+	p.pmu.RUnlock()
+
+	// ensure socket removal so ephemeral directory is empty at revert
+	if err := os.Remove(p.final.Session[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
+		errs[1] = err
+	}
+	if p.final.System[1] != "" {
+		if err := os.Remove(p.final.System[1]); err != nil && !errors.Is(err, os.ErrNotExist) {
+			errs[2] = err
+		}
+	}
+
+	return errors.Join(errs[:]...)
+}
+
+// Close cancels the context passed to the helper instance attached to xdg-dbus-proxy.
+func (p *Proxy) Close() {
+	p.pmu.Lock()
+	defer p.pmu.Unlock()
+
+	if p.cancel == nil {
+		panic("dbus: not started")
+	}
+	p.cancel(proxyClosed)
+}
+
+func argF(argsFd, statFd int) []string {
+	if statFd == -1 {
+		return []string{"--args=" + strconv.Itoa(argsFd)}
+	} else {
+		return []string{"--args=" + strconv.Itoa(argsFd), "--fd=" + strconv.Itoa(statFd)}
+	}
+}

internal/dbus/proc_test.go

@@ -0,0 +1,11 @@
+package dbus_test
+
+import (
+	"os"
+	"testing"
+
+	"hakurei.app/container"
+	"hakurei.app/internal/helper"
+)
+
+func TestMain(m *testing.M) { container.TryArgv0(nil); helper.InternalHelperStub(); os.Exit(m.Run()) }

internal/dbus/proxy.go

@@ -0,0 +1,105 @@
+package dbus
+
+import (
+	"context"
+	"io"
+	"sync"
+	"syscall"
+
+	"hakurei.app/hst"
+	"hakurei.app/internal/helper"
+	"hakurei.app/message"
+)
+
+// 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"
+
+// Proxy holds the state of a xdg-dbus-proxy process, and should never be copied.
+type Proxy struct {
+	helper helper.Helper
+	ctx    context.Context
+	msg    message.Msg
+
+	cancel context.CancelCauseFunc
+	cause  func() error
+
+	final      *Final
+	output     io.Writer
+	useSandbox bool
+
+	name string
+
+	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 *hst.BusConfig) (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, Args(session, sessionBus)...)
+	}
+	if system != nil {
+		if err = system.CheckInterfaces("system"); err != nil {
+			return
+		}
+		args = append(args, Args(system, 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, msg message.Msg, final *Final, output io.Writer) *Proxy {
+	return &Proxy{name: ProxyName, ctx: ctx, msg: msg, final: final, output: output, useSandbox: true}
+}

internal/dbus/samples_test.go

@@ -0,0 +1,214 @@
+package dbus_test
+
+import (
+	"hakurei.app/hst"
+)
+
+const (
+	sampleHostPath = "/tmp/bus"
+	sampleHostAddr = "unix:path=" + sampleHostPath
+	sampleBindPath = "/tmp/proxied_bus"
+)
+
+var samples = []dbusTestCase{
+	{
+		"org.chromium.Chromium", &hst.BusConfig{
+			See: nil,
+			Talk: []string{"org.freedesktop.Notifications", "org.freedesktop.FileManager1", "org.freedesktop.ScreenSaver",
+				"org.freedesktop.secrets", "org.kde.kwalletd5", "org.kde.kwalletd6", "org.gnome.SessionManager"},
+			Own: []string{"org.chromium.Chromium.*", "org.mpris.MediaPlayer2.org.chromium.Chromium.*",
+				"org.mpris.MediaPlayer2.chromium.*"},
+			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+			Log:       false,
+			Filter:    true,
+		}, false, false,
+		[2]string{sampleHostAddr, sampleBindPath},
+		[]string{
+			sampleHostAddr,
+			sampleBindPath,
+			"--filter",
+			"--talk=org.freedesktop.Notifications",
+			"--talk=org.freedesktop.FileManager1",
+			"--talk=org.freedesktop.ScreenSaver",
+			"--talk=org.freedesktop.secrets",
+			"--talk=org.kde.kwalletd5",
+			"--talk=org.kde.kwalletd6",
+			"--talk=org.gnome.SessionManager",
+			"--own=org.chromium.Chromium.*",
+			"--own=org.mpris.MediaPlayer2.org.chromium.Chromium.*",
+			"--own=org.mpris.MediaPlayer2.chromium.*",
+			"--call=org.freedesktop.portal.*=*",
+			"--broadcast=org.freedesktop.portal.*=@/org/freedesktop/portal/*",
+		},
+	},
+	{
+		"org.chromium.Chromium+", &hst.BusConfig{
+			See:       nil,
+			Talk:      []string{"org.bluez", "org.freedesktop.Avahi", "org.freedesktop.UPower"},
+			Own:       nil,
+			Call:      nil,
+			Broadcast: nil,
+			Log:       false,
+			Filter:    true,
+		}, false, false,
+		[2]string{sampleHostAddr, sampleBindPath},
+		[]string{
+			sampleHostAddr,
+			sampleBindPath,
+			"--filter",
+			"--talk=org.bluez",
+			"--talk=org.freedesktop.Avahi",
+			"--talk=org.freedesktop.UPower",
+		},
+	},
+
+	{
+		"dev.vencord.Vesktop", &hst.BusConfig{
+			See:       nil,
+			Talk:      []string{"org.freedesktop.Notifications", "org.kde.StatusNotifierWatcher"},
+			Own:       []string{"dev.vencord.Vesktop.*", "org.mpris.MediaPlayer2.dev.vencord.Vesktop.*"},
+			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+			Log:       false,
+			Filter:    true,
+		}, false, false,
+		[2]string{sampleHostAddr, sampleBindPath},
+		[]string{
+			sampleHostAddr,
+			sampleBindPath,
+			"--filter",
+			"--talk=org.freedesktop.Notifications",
+			"--talk=org.kde.StatusNotifierWatcher",
+			"--own=dev.vencord.Vesktop.*",
+			"--own=org.mpris.MediaPlayer2.dev.vencord.Vesktop.*",
+			"--call=org.freedesktop.portal.*=*",
+			"--broadcast=org.freedesktop.portal.*=@/org/freedesktop/portal/*"},
+	},
+
+	{
+		"uk.gensokyo.CrashTestDummy", &hst.BusConfig{
+			See:       []string{"uk.gensokyo.CrashTestDummy1"},
+			Talk:      []string{"org.freedesktop.Notifications"},
+			Own:       []string{"uk.gensokyo.CrashTestDummy.*", "org.mpris.MediaPlayer2.uk.gensokyo.CrashTestDummy.*"},
+			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+			Log:       true,
+			Filter:    true,
+		}, false, false,
+		[2]string{sampleHostAddr, sampleBindPath},
+		[]string{
+			sampleHostAddr,
+			sampleBindPath,
+			"--filter",
+			"--see=uk.gensokyo.CrashTestDummy1",
+			"--talk=org.freedesktop.Notifications",
+			"--own=uk.gensokyo.CrashTestDummy.*",
+			"--own=org.mpris.MediaPlayer2.uk.gensokyo.CrashTestDummy.*",
+			"--call=org.freedesktop.portal.*=*",
+			"--broadcast=org.freedesktop.portal.*=@/org/freedesktop/portal/*",
+			"--log"},
+	},
+	{
+		"uk.gensokyo.CrashTestDummy1", &hst.BusConfig{
+			See:       []string{"uk.gensokyo.CrashTestDummy"},
+			Talk:      []string{"org.freedesktop.Notifications"},
+			Own:       []string{"uk.gensokyo.CrashTestDummy1.*", "org.mpris.MediaPlayer2.uk.gensokyo.CrashTestDummy1.*"},
+			Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+			Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+			Log:       true,
+			Filter:    true,
+		}, false, true,
+		[2]string{sampleHostAddr, sampleBindPath},
+		[]string{
+			sampleHostAddr,
+			sampleBindPath,
+			"--filter",
+			"--see=uk.gensokyo.CrashTestDummy",
+			"--talk=org.freedesktop.Notifications",
+			"--own=uk.gensokyo.CrashTestDummy1.*",
+			"--own=org.mpris.MediaPlayer2.uk.gensokyo.CrashTestDummy1.*",
+			"--call=org.freedesktop.portal.*=*",
+			"--broadcast=org.freedesktop.portal.*=@/org/freedesktop/portal/*",
+			"--log"},
+	},
+}
+
+type dbusTestCase struct {
+	id       string
+	c        *hst.BusConfig
+	wantErr  bool
+	wantErrF bool
+	bus      [2]string
+	want     []string
+}
+
+var (
+	testCasesExt = func() []dbusTestCase {
+		testCases := make([]dbusTestCase, len(samples)*2)
+		for i := range samples {
+			testCases[i] = samples[i]
+
+			fi := &testCases[len(samples)+i]
+			*fi = samples[i]
+
+			// create null-injected test cases
+			fi.wantErr = true
+			injectNulls := func(t *[]string) {
+				f := make([]string, len(*t))
+				for i := range f {
+					f[i] = "\x00" + (*t)[i] + "\x00"
+				}
+				*t = f
+			}
+
+			fi.c = new(hst.BusConfig)
+			*fi.c = *samples[i].c
+			injectNulls(&fi.c.See)
+			injectNulls(&fi.c.Talk)
+			injectNulls(&fi.c.Own)
+		}
+		return testCases
+	}()
+
+	testCasePairs = func() map[string][2]dbusTestCase {
+		// enumerate test case pairs
+		var pc int
+		for _, tc := range samples {
+			if tc.id != "" {
+				pc++
+			}
+		}
+		pairs := make(map[string][2]dbusTestCase, pc)
+		for i, tc := range testCasesExt {
+			if tc.id == "" {
+				continue
+			}
+
+			// skip already enumerated system bus test
+			if tc.id[len(tc.id)-1] == '+' {
+				continue
+			}
+
+			ftp := [2]dbusTestCase{tc}
+
+			// system proxy tests always place directly after its user counterpart with id ending in +
+			if i+1 < len(testCasesExt) && testCasesExt[i+1].id[len(testCasesExt[i+1].id)-1] == '+' {
+				// attach system bus config
+				ftp[1] = testCasesExt[i+1]
+
+				// check for misplaced/mismatching tests
+				if ftp[0].wantErr != ftp[1].wantErr || ftp[0].id+"+" != ftp[1].id {
+					panic("mismatching session/system pairing")
+				}
+			}
+
+			k := tc.id
+			if tc.wantErr {
+				k = "malformed_" + k
+			}
+			pairs[k] = ftp
+		}
+		return pairs
+	}()
+)

internal/dbus/testdata/dev.vencord.Vesktop.json

@@ -0,0 +1,18 @@
+{
+  "talk":[
+    "org.freedesktop.Notifications",
+    "org.kde.StatusNotifierWatcher"
+  ],
+  "own":[
+    "dev.vencord.Vesktop.*",
+    "org.mpris.MediaPlayer2.dev.vencord.Vesktop.*"
+  ],
+  "call":{
+    "org.freedesktop.portal.*":"*"
+  },
+  "broadcast":{
+    "org.freedesktop.portal.*":"@/org/freedesktop/portal/*"
+  },
+
+  "filter":true
+}

internal/dbus/testdata/org.chromium.Chromium+.json

@@ -0,0 +1,9 @@
+{
+  "talk":[
+    "org.bluez",
+    "org.freedesktop.Avahi",
+    "org.freedesktop.UPower"
+  ],
+
+  "filter":true
+}

internal/dbus/testdata/org.chromium.Chromium.json

@@ -0,0 +1,24 @@
+{
+  "talk":[
+    "org.freedesktop.Notifications",
+    "org.freedesktop.FileManager1",
+    "org.freedesktop.ScreenSaver",
+    "org.freedesktop.secrets",
+    "org.kde.kwalletd5",
+    "org.kde.kwalletd6",
+    "org.gnome.SessionManager"
+  ],
+  "own":[
+    "org.chromium.Chromium.*",
+    "org.mpris.MediaPlayer2.org.chromium.Chromium.*",
+    "org.mpris.MediaPlayer2.chromium.*"
+  ],
+  "call":{
+    "org.freedesktop.portal.*":"*"
+  },
+  "broadcast":{
+    "org.freedesktop.portal.*":"@/org/freedesktop/portal/*"
+  },
+
+  "filter":true
+}

internal/dbus/testdata/uk.gensokyo.CrashTestDummy.json

@@ -0,0 +1,21 @@
+{
+  "see": [
+    "uk.gensokyo.CrashTestDummy1"
+  ],
+  "talk":[
+    "org.freedesktop.Notifications"
+  ],
+  "own":[
+    "uk.gensokyo.CrashTestDummy.*",
+    "org.mpris.MediaPlayer2.uk.gensokyo.CrashTestDummy.*"
+  ],
+  "call":{
+    "org.freedesktop.portal.*":"*"
+  },
+  "broadcast":{
+    "org.freedesktop.portal.*":"@/org/freedesktop/portal/*"
+  },
+
+  "log": true,
+  "filter":true
+}