test(xtest): compare live Xvfb captures independently of the server build

The live comparison failed on other Xvfb builds because goldens embed
server-chosen values. Each golden now lists its server-chosen fields by
offset (root window, visual, colormap, interned atom, resource IDs,
extension opcodes and event/error bases, timestamps). -update records
their capture-time values in testdata/golden/xvfb-roles.json; compare mode
checks the golden holds the recorded values and the live packet the live
server's, masks both and compares the rest exactly.

ListExtensions and Render QueryPictFormats depend on the server build, so
live compare checks their framing, list counts, bound extensions and the
root visual's picture format instead of bytes. XTURBO_XVFB_ARGS adds Xvfb
options to simulate another server layout. Committed goldens and unit
tests are unchanged.

commit: 722264ac773fc5df4f73671ee4fcce79537e93a6
author: brice · 12h ago · 2026-10-22 08:22 UTC
parent: d5bc75b
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email
checks: 4/4

3 files · +296 -36

M internal/xtest/README.md +21 -4

@@ -1,10 +1,27 @@
1	1		# Wire goldens
2	2
3	3		`make xserver` captures from a fresh Xvfb and compares every packet with the
4		-	committed golden, failing on any difference. Server timestamps
5		-	(PropertyNotify time, XFIXES SelectionNotify timestamps) vary per run and are
6		-	excluded from the comparison. The test is skipped when Xvfb is not installed.
7		-	Rewrite the goldens from the repository root with:
	4	+	committed golden. Comparison is independent of the server build:
	5	+
	6	+	- Server-chosen values (root window, visual, colormap, interned atom,
	7	+	resource IDs from the client's resource base, extension opcodes and
	8	+	event/error bases) are listed per golden by field offset in
	9	+	`serverFields`. `-update` records their capture-time values in
	10	+	`testdata/golden/xvfb-roles.json`. Compare mode checks that the golden holds
	11	+	the recorded value and the live packet holds the live server's value, masks
	12	+	both, then compares the remaining bytes exactly. Server timestamps are
	13	+	masked without a value check.
	14	+	- `ListExtensions` and Render `QueryPictFormats` replies depend on how the
	15	+	server was built (extension list, visuals, formats), so live compare
	16	+	checks invariants: framing, counts matching list lengths, the bound
	17	+	extensions present, the root visual mapped to the format CreatePicture uses.
	18	+
	19	+	Unit tests still decode the committed goldens byte-exactly. The test is
	20	+	skipped when Xvfb is not installed. `XTURBO_XVFB_ARGS` adds Xvfb options to
	21	+	simulate another server layout, e.g. `XTURBO_XVFB_ARGS="-extension GLX"`.
	22	+	Screen size and depth (800x600x24) and the bound extensions are capture
	23	+	inputs and must stay as captured. Rewrite the goldens from the repository
	24	+	root with:
8	25
9	26		```
10	27		PATH="$PATH:/usr/sbin" go test -tags xserver ./internal/xtest -update

@@ -1,10 +1,27 @@
1		# Wire goldens	1		# Wire goldens
2			2
3		`make xserver` captures from a fresh Xvfb and compares every packet with the	3		`make xserver` captures from a fresh Xvfb and compares every packet with the
4	-	committed golden, failing on any difference. Server timestamps	4	+	committed golden. Comparison is independent of the server build:
5	-	(PropertyNotify time, XFIXES SelectionNotify timestamps) vary per run and are	5	+
6	-	excluded from the comparison. The test is skipped when Xvfb is not installed.	6	+	- Server-chosen values (root window, visual, colormap, interned atom,
7	-	Rewrite the goldens from the repository root with:	7	+	resource IDs from the client's resource base, extension opcodes and
			8	+	event/error bases) are listed per golden by field offset in
			9	+	`serverFields`. `-update` records their capture-time values in
			10	+	`testdata/golden/xvfb-roles.json`. Compare mode checks that the golden holds
			11	+	the recorded value and the live packet holds the live server's value, masks
			12	+	both, then compares the remaining bytes exactly. Server timestamps are
			13	+	masked without a value check.
			14	+	- `ListExtensions` and Render `QueryPictFormats` replies depend on how the
			15	+	server was built (extension list, visuals, formats), so live compare
			16	+	checks invariants: framing, counts matching list lengths, the bound
			17	+	extensions present, the root visual mapped to the format CreatePicture uses.
			18	+
			19	+	Unit tests still decode the committed goldens byte-exactly. The test is
			20	+	skipped when Xvfb is not installed. `XTURBO_XVFB_ARGS` adds Xvfb options to
			21	+	simulate another server layout, e.g. `XTURBO_XVFB_ARGS="-extension GLX"`.
			22	+	Screen size and depth (800x600x24) and the bound extensions are capture
			23	+	inputs and must stay as captured. Rewrite the goldens from the repository
			24	+	root with:
8			25
9		```	26		```
10		PATH="$PATH:/usr/sbin" go test -tags xserver ./internal/xtest -update	27		PATH="$PATH:/usr/sbin" go test -tags xserver ./internal/xtest -update

M internal/xtest/capture_test.go +256 -32


@@ -6,13 +6,16 @@ import (
6	6		"bytes"
7	7		"encoding/binary"
8	8		"encoding/hex"
	9	+	"encoding/json"
9	10		"flag"
10	11		"fmt"
11	12		"io"
	13	+	"maps"
12	14		"net"
13	15		"os"
14	16		"os/exec"
15	17		"path/filepath"
	18	+	"slices"
16	19		"strconv"
17	20		"strings"
18	21		"testing"

@@ -23,11 +26,67 @@ import (
23	26
24	27		var update = flag.Bool("update", false, "rewrite wire goldens from Xvfb instead of comparing against them")
25	28
26		-	// volatile lists server-time fields that differ on every run; comparison
27		-	// ignores these byte ranges [from, to). Everything else must match exactly.
28		-	var volatile = map[string][][2]int{
29		-	"xproto/PropertyNotify.event.hex": {{12, 16}}, // time
30		-	"xfixes/SelectionNotify.event.hex": {{16, 24}}, // timestamp, selection_timestamp
	29	+	// field is a server-dependent value inside a golden: the size-byte
	30	+	// little-endian integer at Off must equal the server's value for Role.
	31	+	type field struct {
	32	+	Off, Size int
	33	+	Role string
	34	+	}
	35	+
	36	+	// serverFields lists, per golden, every value the X server chooses: resource
	37	+	// IDs derived from a server-assigned base, the root window and its visual and
	38	+	// colormap, interned atoms, extension opcodes and bases, and timestamps.
	39	+	// Compare mode checks that the golden holds the value recorded at capture
	40	+	// (xvfb-roles.json) and the live packet holds the live server's value, then
	41	+	// masks both and compares the remaining bytes exactly. Role "time" is a
	42	+	// per-run server timestamp and is masked without a value check.
	43	+	var serverFields = map[string][]field{
	44	+	"xproto/MapWindow.req": {{4, 4, "root"}},
	45	+	"xproto/GetGeometry.req": {{4, 4, "root"}},
	46	+	"xproto/ChangeProperty.req": {{4, 4, "root"}, {8, 4, "atom"}},
	47	+	"xproto/CreateWindow.req": {{4, 4, "child"}, {8, 4, "root"}},
	48	+	"xproto/ChangeWindowAttributes.req": {{4, 4, "child"}},
	49	+	"xproto/ConfigureWindow.req": {{4, 4, "child"}},
	50	+	"xproto/ConfigureWindowSparse.req": {{4, 4, "child"}},
	51	+	"xproto/ConfigureWindowAll.req": {{4, 4, "child"}, {32, 4, "sibling"}},
	52	+	"render/CreatePicture.req": {{0, 1, "renderMajor"}, {4, 4, "picture"}, {8, 4, "child"}, {12, 4, "rootFormat"}},
	53	+	"res/QueryClientIds.req": {{0, 1, "resMajor"}},
	54	+	"xfixes/QueryVersion.req": {{0, 1, "xfixesMajor"}},
	55	+	"xproto/QueryExtension.reply": {{9, 1, "xfixesMajor"}, {10, 1, "xfixesEvent"}, {11, 1, "xfixesError"}},
	56	+	"xproto/GetGeometry.reply": {{8, 4, "root"}},
	57	+	"xproto/InternAtom.reply": {{8, 4, "atom"}},
	58	+	"xproto/GetWindowAttributes.reply": {{8, 4, "rootVisual"}, {28, 4, "rootColormap"}},
	59	+	"xproto/QueryTree.reply": {{8, 4, "root"}, {32, 4, "sibling"}, {36, 4, "child"}},
	60	+	"res/QueryClientIds.reply": {{44, 4, "base"}},
	61	+	"xproto/CreateNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
	62	+	"xproto/MapRequest.event": {{4, 4, "root"}, {8, 4, "client2"}},
	63	+	"xproto/ConfigureRequest.event": {{4, 4, "root"}, {8, 4, "client2"}},
	64	+	"xproto/MapNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
	65	+	"xproto/UnmapNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
	66	+	"xproto/DestroyNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
	67	+	"xproto/PropertyNotify.event": {{4, 4, "root"}, {8, 4, "atom"}, {12, 4, "time"}},
	68	+	"xproto/ClientMessage.event": {{4, 4, "client2"}, {8, 4, "atom"}},
	69	+	"xproto/SelectionNotify.event": {{8, 4, "child"}},
	70	+	"xfixes/SelectionNotify.event": {{0, 1, "xfixesEvent"}, {4, 4, "root"}, {8, 4, "client2"}, {16, 4, "time"}, {20, 4, "time"}},
	71	+	"xproto/BadWindow.error": {{4, 4, "badWindow"}},
	72	+	"xfixes/BadRegion.error": {{1, 1, "xfixesError"}, {4, 4, "badRegion"}, {10, 1, "xfixesMajor"}},
	73	+	}
	74	+
	75	+	// structural replies depend on the server build itself (extension list,
	76	+	// visuals and picture formats), so live compare checks invariants instead of
	77	+	// bytes; unit tests still decode the committed golden byte-exactly.
	78	+	var structural = map[string]func(p []byte, roles map[string]uint32) error{
	79	+	"xproto/ListExtensions.reply": checkListExtensions,
	80	+	"render/QueryPictFormats.reply": checkQueryPictFormats,
	81	+	}
	82	+
	83	+	const rolesPath = "../../testdata/golden/xvfb-roles.json"
	84	+
	85	+	// xvfbArgs lets a run simulate a different server layout, e.g.
	86	+	// XTURBO_XVFB_ARGS="-extension GLX" shifts resource IDs, atoms and visuals.
	87	+	func xvfbArgs() []string {
	88	+	args := []string{"-displayfd", "3", "-screen", "0", "800x600x24", "-nolisten", "tcp", "-ac"}
	89	+	return append(args, strings.Fields(os.Getenv("XTURBO_XVFB_ARGS"))...)
31	90		}
32	91
33	92		// TestCaptureRequests drives a fresh Xvfb through a raw socketpair tee. By

@@ -43,7 +102,7 @@ func TestCaptureRequests(t *testing.T) {
43	102		t.Fatal(err)
44	103		}
45	104		defer r.Close()
46		-	cmd := exec.Command("Xvfb", "-displayfd", "3", "-screen", "0", "800x600x24", "-nolisten", "tcp", "-ac")
	105	+	cmd := exec.Command("Xvfb", xvfbArgs()...)
47	106		cmd.ExtraFiles = []*os.File{w}
48	107		var log bytes.Buffer
49	108		cmd.Stderr = &log

@@ -512,12 +571,6 @@ func TestCaptureRequests(t *testing.T) {
512	571		if len(events) != 10 \|\| len(xerrors) != 3 {
513	572		t.Fatalf("captured %d events, %d errors", len(events), len(xerrors))
514	573		}
515		-	for name, p := range events {
516		-	golden(t, name+".event.hex", "# source: Xvfb event via raw socketpair tee; triggered by an independent second client or reference request\n", p)
517		-	}
518		-	for name, p := range xerrors {
519		-	golden(t, name+".error.hex", "# source: Xvfb error via raw socketpair tee to an independent reference request\n", p)
520		-	}
521	574		// Closing the client drains the request direction; wait before inspecting tee.
522	575		client.Close()
523	576		select {

@@ -577,40 +630,211 @@ func TestCaptureRequests(t *testing.T) {
577	630		if len(captured) != 12 \|\| len(replies) != 11 {
578	631		t.Fatal("missing captured requests or replies")
579	632		}
	633	+	out := map[string][]byte{}
580	634		for name, p := range replies {
581		-	golden(t, name+".reply.hex", "# source: Xvfb reply via raw socketpair tee to an independent reference request\n", p)
	635	+	out[name+".reply"] = p
582	636		}
583	637		for name, p := range captured {
584		-	golden(t, name+".req.hex", "# source: Xvfb via raw socketpair tee; independent reference encoder; server accepted\n", p)
	638	+	out[name+".req"] = p
585	639		}
586		-	}
587		-
588		-	// golden writes p (with -update) or compares it with the committed golden.
589		-	func golden(t *testing.T, name, source string, p []byte) {
590		-	t.Helper()
591		-	path := filepath.Join("../../testdata/golden", name)
592		-	if !*update {
593		-	want, err := LoadHex(path)
594		-	if err != nil {
595		-	t.Errorf("%s: %v (run with -update to create it)", name, err)
596		-	return
	640	+	for name, p := range events {
	641	+	out[name+".event"] = p
	642	+	}
	643	+	for name, p := range xerrors {
	644	+	out[name+".error"] = p
	645	+	}
	646	+	// Server-chosen values, keyed by the roles used in serverFields.
	647	+	roles := map[string]uint32{
	648	+	"root": root, "atom": atom, "base": base, "child": child, "sibling": sibling, "picture": picture,
	649	+	"client2": client2, "badWindow": base \| 0x7777, "badRegion": base \| 0x8888,
	650	+	"rootVisual": rootVisual, "rootColormap": binary.LittleEndian.Uint32(setup[screenOff+4:]), "rootFormat": format,
	651	+	"xfixesMajor": uint32(major), "xfixesEvent": uint32(xfixesEvent), "xfixesError": uint32(xfixesError),
	652	+	"resMajor": uint32(resMajor), "renderMajor": uint32(renderMajor),
	653	+	}
	654	+	if *update {
	655	+	for name, p := range out {
	656	+	writeGolden(t, name, p)
597	657		}
598		-	got := bytes.Clone(p)
599		-	if len(got) == len(want) {
600		-	for _, r := range volatile[name] {
601		-	copy(got[r[0]:r[1]], want[r[0]:r[1]])
602		-	}
	658	+	rolesJSON, err := json.MarshalIndent(roles, "", " ")
	659	+	if err != nil {
	660	+	t.Fatal(err)
603	661		}
604		-	if !bytes.Equal(got, want) {
605		-	t.Errorf("%s differs from live Xvfb:\n got %x\nwant %x", name, p, want)
	662	+	if err := os.WriteFile(rolesPath, append(rolesJSON, '\n'), 0644); err != nil {
	663	+	t.Fatal(err)
606	664		}
607	665		return
608	666		}
	667	+	rolesJSON, err := os.ReadFile(rolesPath)
	668	+	if err != nil {
	669	+	t.Fatal(err)
	670	+	}
	671	+	var capturedRoles map[string]uint32
	672	+	if err := json.Unmarshal(rolesJSON, &capturedRoles); err != nil {
	673	+	t.Fatal(err)
	674	+	}
	675	+	for _, role := range slices.Sorted(maps.Keys(roles)) {
	676	+	if roles[role] != capturedRoles[role] {
	677	+	t.Logf("server-chosen %s: live %#x, golden %#x", role, roles[role], capturedRoles[role])
	678	+	}
	679	+	}
	680	+	for name, p := range out {
	681	+	compareGolden(t, name, p, roles, capturedRoles)
	682	+	}
	683	+	}
	684	+
	685	+	var sources = map[string]string{
	686	+	"req": "# source: Xvfb via raw socketpair tee; independent reference encoder; server accepted\n",
	687	+	"reply": "# source: Xvfb reply via raw socketpair tee to an independent reference request\n",
	688	+	"event": "# source: Xvfb event via raw socketpair tee; triggered by an independent second client or reference request\n",
	689	+	"error": "# source: Xvfb error via raw socketpair tee to an independent reference request\n",
	690	+	}
	691	+
	692	+	func writeGolden(t *testing.T, name string, p []byte) {
	693	+	t.Helper()
	694	+	path := filepath.Join("../../testdata/golden", name+".hex")
609	695		if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
610	696		t.Fatal(err)
611	697		}
	698	+	source := sources[name[strings.LastIndexByte(name, '.')+1:]]
612	699		text := source + "# xtrace fallback: local xtrace is glibc's execution tracer, not X11 xtrace\n" + hex.EncodeToString(p) + "\n"
613	700		if err := os.WriteFile(path, []byte(text), 0644); err != nil {
614	701		t.Fatal(err)
615	702		}
616	703		}
	704	+
	705	+	// compareGolden checks a live packet against the committed golden without
	706	+	// depending on the server build: server-chosen fields must hold each side's
	707	+	// own value (live roles, recorded roles) and are masked before an exact
	708	+	// comparison; structural replies are checked for invariants only.
	709	+	func compareGolden(t *testing.T, name string, live []byte, roles, recorded map[string]uint32) {
	710	+	t.Helper()
	711	+	want, err := LoadHex(filepath.Join("../../testdata/golden", name+".hex"))
	712	+	if err != nil {
	713	+	t.Errorf("%s: %v (run with -update to create it)", name, err)
	714	+	return
	715	+	}
	716	+	if check := structural[name]; check != nil {
	717	+	if err := check(live, roles); err != nil {
	718	+	t.Errorf("%s (live): %v", name, err)
	719	+	}
	720	+	if err := check(want, recorded); err != nil {
	721	+	t.Errorf("%s (golden): %v", name, err)
	722	+	}
	723	+	return
	724	+	}
	725	+	got, exp, err := normalize(name, live, roles), normalize(name, want, recorded), error(nil)
	726	+	for _, e := range []struct {
	727	+	side string
	728	+	err error
	729	+	}{{"live", got.err}, {"golden", exp.err}} {
	730	+	if e.err != nil {
	731	+	t.Errorf("%s (%s): %v", name, e.side, e.err)
	732	+	err = e.err
	733	+	}
	734	+	}
	735	+	if err == nil && !bytes.Equal(got.b, exp.b) {
	736	+	t.Errorf("%s differs from live Xvfb after masking server-chosen fields:\n got %x\nwant %x", name, live, want)
	737	+	}
	738	+	}
	739	+
	740	+	type normalized struct {
	741	+	b []byte
	742	+	err error
	743	+	}
	744	+
	745	+	// normalize verifies each server-chosen field of p holds roles[Role] and
	746	+	// replaces it with zero bytes.
	747	+	func normalize(name string, p []byte, roles map[string]uint32) normalized {
	748	+	b := bytes.Clone(p)
	749	+	for _, f := range serverFields[name] {
	750	+	if f.Off+f.Size > len(b) {
	751	+	return normalized{err: fmt.Errorf("field %s at %d beyond %d bytes", f.Role, f.Off, len(b))}
	752	+	}
	753	+	if f.Role != "time" {
	754	+	v, ok := roles[f.Role]
	755	+	if !ok {
	756	+	return normalized{err: fmt.Errorf("no recorded value for role %s", f.Role)}
	757	+	}
	758	+	var got uint32
	759	+	if f.Size == 1 {
	760	+	got = uint32(b[f.Off])
	761	+	} else {
	762	+	got = binary.LittleEndian.Uint32(b[f.Off:])
	763	+	}
	764	+	if got != v {
	765	+	return normalized{err: fmt.Errorf("field %s at %d = %#x, want %#x", f.Role, f.Off, got, v)}
	766	+	}
	767	+	}
	768	+	clear(b[f.Off : f.Off+f.Size])
	769	+	}
	770	+	return normalized{b: b}
	771	+	}
	772	+
	773	+	// checkListExtensions: a framed reply whose STR list holds exactly names_len
	774	+	// entries filling the reply, including the extensions xturbo binds.
	775	+	func checkListExtensions(p []byte, _ map[string]uint32) error {
	776	+	if len(p) < 32 \|\| p[0] != 1 \|\| len(p) != 32+4*int(binary.LittleEndian.Uint32(p[4:])) {
	777	+	return fmt.Errorf("bad framing")
	778	+	}
	779	+	names := map[string]bool{}
	780	+	off := 32
	781	+	for range int(p[1]) {
	782	+	if off >= len(p) \|\| off+1+int(p[off]) > len(p) {
	783	+	return fmt.Errorf("STR list overruns the reply")
	784	+	}
	785	+	names[string(p[off+1:off+1+int(p[off])])] = true
	786	+	off += 1 + int(p[off])
	787	+	}
	788	+	if (off+3)&^3 != len(p) {
	789	+	return fmt.Errorf("STR list ends at %d, reply has %d bytes", off, len(p))
	790	+	}
	791	+	for _, want := range []string{"BIG-REQUESTS", "XC-MISC", "XFIXES", "RENDER", "SHAPE", "Composite", "X-Resource", "Generic Event Extension"} {
	792	+	if !names[want] {
	793	+	return fmt.Errorf("missing extension %q", want)
	794	+	}
	795	+	}
	796	+	return nil
	797	+	}
	798	+
	799	+	// checkQueryPictFormats: declared counts match the list sizes exactly and the
	800	+	// root visual maps to the picture format CreatePicture used.
	801	+	func checkQueryPictFormats(p []byte, roles map[string]uint32) error {
	802	+	u32 := binary.LittleEndian.Uint32
	803	+	if len(p) < 32 \|\| p[0] != 1 \|\| len(p) != 32+4*int(u32(p[4:])) {
	804	+	return fmt.Errorf("bad framing")
	805	+	}
	806	+	formats, screens, subpixels := int(u32(p[8:])), int(u32(p[12:])), int(u32(p[24:]))
	807	+	off := 32 + 28*formats
	808	+	found := false
	809	+	for range screens {
	810	+	if off+8 > len(p) {
	811	+	return fmt.Errorf("screens overrun")
	812	+	}
	813	+	depths := int(u32(p[off:]))
	814	+	off += 8
	815	+	for range depths {
	816	+	if off+8 > len(p) {
	817	+	return fmt.Errorf("depths overrun")
	818	+	}
	819	+	visuals := int(binary.LittleEndian.Uint16(p[off+2:]))
	820	+	off += 8
	821	+	for range visuals {
	822	+	if off+8 > len(p) {
	823	+	return fmt.Errorf("visuals overrun")
	824	+	}
	825	+	if u32(p[off:]) == roles["rootVisual"] && u32(p[off+4:]) == roles["rootFormat"] {
	826	+	found = true
	827	+	}
	828	+	off += 8
	829	+	}
	830	+	}
	831	+	}
	832	+	off += 4 * subpixels
	833	+	if off != len(p) {
	834	+	return fmt.Errorf("lists end at %d, reply has %d bytes", off, len(p))
	835	+	}
	836	+	if !found {
	837	+	return fmt.Errorf("root visual %#x does not map to format %#x", roles["rootVisual"], roles["rootFormat"])
	838	+	}
	839	+	return nil
	840	+	}


@@ -6,13 +6,16 @@ import (
6		"bytes"	6		"bytes"
7		"encoding/binary"	7		"encoding/binary"
8		"encoding/hex"	8		"encoding/hex"
			9	+	"encoding/json"
9		"flag"	10		"flag"
10		"fmt"	11		"fmt"
11		"io"	12		"io"
			13	+	"maps"
12		"net"	14		"net"
13		"os"	15		"os"
14		"os/exec"	16		"os/exec"
15		"path/filepath"	17		"path/filepath"
			18	+	"slices"
16		"strconv"	19		"strconv"
17		"strings"	20		"strings"
18		"testing"	21		"testing"

@@ -23,11 +26,67 @@ import (
23			26
24		var update = flag.Bool("update", false, "rewrite wire goldens from Xvfb instead of comparing against them")	27		var update = flag.Bool("update", false, "rewrite wire goldens from Xvfb instead of comparing against them")
25			28
26	-	// volatile lists server-time fields that differ on every run; comparison	29	+	// field is a server-dependent value inside a golden: the size-byte
27	-	// ignores these byte ranges [from, to). Everything else must match exactly.	30	+	// little-endian integer at Off must equal the server's value for Role.
28	-	var volatile = map[string][][2]int{	31	+	type field struct {
29	-	"xproto/PropertyNotify.event.hex": {{12, 16}}, // time	32	+	Off, Size int
30	-	"xfixes/SelectionNotify.event.hex": {{16, 24}}, // timestamp, selection_timestamp	33	+	Role string
			34	+	}
			35	+
			36	+	// serverFields lists, per golden, every value the X server chooses: resource
			37	+	// IDs derived from a server-assigned base, the root window and its visual and
			38	+	// colormap, interned atoms, extension opcodes and bases, and timestamps.
			39	+	// Compare mode checks that the golden holds the value recorded at capture
			40	+	// (xvfb-roles.json) and the live packet holds the live server's value, then
			41	+	// masks both and compares the remaining bytes exactly. Role "time" is a
			42	+	// per-run server timestamp and is masked without a value check.
			43	+	var serverFields = map[string][]field{
			44	+	"xproto/MapWindow.req": {{4, 4, "root"}},
			45	+	"xproto/GetGeometry.req": {{4, 4, "root"}},
			46	+	"xproto/ChangeProperty.req": {{4, 4, "root"}, {8, 4, "atom"}},
			47	+	"xproto/CreateWindow.req": {{4, 4, "child"}, {8, 4, "root"}},
			48	+	"xproto/ChangeWindowAttributes.req": {{4, 4, "child"}},
			49	+	"xproto/ConfigureWindow.req": {{4, 4, "child"}},
			50	+	"xproto/ConfigureWindowSparse.req": {{4, 4, "child"}},
			51	+	"xproto/ConfigureWindowAll.req": {{4, 4, "child"}, {32, 4, "sibling"}},
			52	+	"render/CreatePicture.req": {{0, 1, "renderMajor"}, {4, 4, "picture"}, {8, 4, "child"}, {12, 4, "rootFormat"}},
			53	+	"res/QueryClientIds.req": {{0, 1, "resMajor"}},
			54	+	"xfixes/QueryVersion.req": {{0, 1, "xfixesMajor"}},
			55	+	"xproto/QueryExtension.reply": {{9, 1, "xfixesMajor"}, {10, 1, "xfixesEvent"}, {11, 1, "xfixesError"}},
			56	+	"xproto/GetGeometry.reply": {{8, 4, "root"}},
			57	+	"xproto/InternAtom.reply": {{8, 4, "atom"}},
			58	+	"xproto/GetWindowAttributes.reply": {{8, 4, "rootVisual"}, {28, 4, "rootColormap"}},
			59	+	"xproto/QueryTree.reply": {{8, 4, "root"}, {32, 4, "sibling"}, {36, 4, "child"}},
			60	+	"res/QueryClientIds.reply": {{44, 4, "base"}},
			61	+	"xproto/CreateNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
			62	+	"xproto/MapRequest.event": {{4, 4, "root"}, {8, 4, "client2"}},
			63	+	"xproto/ConfigureRequest.event": {{4, 4, "root"}, {8, 4, "client2"}},
			64	+	"xproto/MapNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
			65	+	"xproto/UnmapNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
			66	+	"xproto/DestroyNotify.event": {{4, 4, "root"}, {8, 4, "client2"}},
			67	+	"xproto/PropertyNotify.event": {{4, 4, "root"}, {8, 4, "atom"}, {12, 4, "time"}},
			68	+	"xproto/ClientMessage.event": {{4, 4, "client2"}, {8, 4, "atom"}},
			69	+	"xproto/SelectionNotify.event": {{8, 4, "child"}},
			70	+	"xfixes/SelectionNotify.event": {{0, 1, "xfixesEvent"}, {4, 4, "root"}, {8, 4, "client2"}, {16, 4, "time"}, {20, 4, "time"}},
			71	+	"xproto/BadWindow.error": {{4, 4, "badWindow"}},
			72	+	"xfixes/BadRegion.error": {{1, 1, "xfixesError"}, {4, 4, "badRegion"}, {10, 1, "xfixesMajor"}},
			73	+	}
			74	+
			75	+	// structural replies depend on the server build itself (extension list,
			76	+	// visuals and picture formats), so live compare checks invariants instead of
			77	+	// bytes; unit tests still decode the committed golden byte-exactly.
			78	+	var structural = map[string]func(p []byte, roles map[string]uint32) error{
			79	+	"xproto/ListExtensions.reply": checkListExtensions,
			80	+	"render/QueryPictFormats.reply": checkQueryPictFormats,
			81	+	}
			82	+
			83	+	const rolesPath = "../../testdata/golden/xvfb-roles.json"
			84	+
			85	+	// xvfbArgs lets a run simulate a different server layout, e.g.
			86	+	// XTURBO_XVFB_ARGS="-extension GLX" shifts resource IDs, atoms and visuals.
			87	+	func xvfbArgs() []string {
			88	+	args := []string{"-displayfd", "3", "-screen", "0", "800x600x24", "-nolisten", "tcp", "-ac"}
			89	+	return append(args, strings.Fields(os.Getenv("XTURBO_XVFB_ARGS"))...)
31		}	90		}
32			91
33		// TestCaptureRequests drives a fresh Xvfb through a raw socketpair tee. By	92		// TestCaptureRequests drives a fresh Xvfb through a raw socketpair tee. By

@@ -43,7 +102,7 @@ func TestCaptureRequests(t *testing.T) {
43		t.Fatal(err)	102		t.Fatal(err)
44		}	103		}
45		defer r.Close()	104		defer r.Close()
46	-	cmd := exec.Command("Xvfb", "-displayfd", "3", "-screen", "0", "800x600x24", "-nolisten", "tcp", "-ac")	105	+	cmd := exec.Command("Xvfb", xvfbArgs()...)
47		cmd.ExtraFiles = []*os.File{w}	106		cmd.ExtraFiles = []*os.File{w}
48		var log bytes.Buffer	107		var log bytes.Buffer
49		cmd.Stderr = &log	108		cmd.Stderr = &log

@@ -512,12 +571,6 @@ func TestCaptureRequests(t *testing.T) {
512		if len(events) != 10 \|\| len(xerrors) != 3 {	571		if len(events) != 10 \|\| len(xerrors) != 3 {
513		t.Fatalf("captured %d events, %d errors", len(events), len(xerrors))	572		t.Fatalf("captured %d events, %d errors", len(events), len(xerrors))
514		}	573		}
515	-	for name, p := range events {
516	-	golden(t, name+".event.hex", "# source: Xvfb event via raw socketpair tee; triggered by an independent second client or reference request\n", p)
517	-	}
518	-	for name, p := range xerrors {
519	-	golden(t, name+".error.hex", "# source: Xvfb error via raw socketpair tee to an independent reference request\n", p)
520	-	}
521		// Closing the client drains the request direction; wait before inspecting tee.	574		// Closing the client drains the request direction; wait before inspecting tee.
522		client.Close()	575		client.Close()
523		select {	576		select {

@@ -577,40 +630,211 @@ func TestCaptureRequests(t *testing.T) {
577		if len(captured) != 12 \|\| len(replies) != 11 {	630		if len(captured) != 12 \|\| len(replies) != 11 {
578		t.Fatal("missing captured requests or replies")	631		t.Fatal("missing captured requests or replies")
579		}	632		}
			633	+	out := map[string][]byte{}
580		for name, p := range replies {	634		for name, p := range replies {
581	-	golden(t, name+".reply.hex", "# source: Xvfb reply via raw socketpair tee to an independent reference request\n", p)	635	+	out[name+".reply"] = p
582		}	636		}
583		for name, p := range captured {	637		for name, p := range captured {
584	-	golden(t, name+".req.hex", "# source: Xvfb via raw socketpair tee; independent reference encoder; server accepted\n", p)	638	+	out[name+".req"] = p
585		}	639		}
586	-	}	640	+	for name, p := range events {
587	-		641	+	out[name+".event"] = p
588	-	// golden writes p (with -update) or compares it with the committed golden.	642	+	}
589	-	func golden(t *testing.T, name, source string, p []byte) {	643	+	for name, p := range xerrors {
590	-	t.Helper()	644	+	out[name+".error"] = p
591	-	path := filepath.Join("../../testdata/golden", name)	645	+	}
592	-	if !*update {	646	+	// Server-chosen values, keyed by the roles used in serverFields.
593	-	want, err := LoadHex(path)	647	+	roles := map[string]uint32{
594	-	if err != nil {	648	+	"root": root, "atom": atom, "base": base, "child": child, "sibling": sibling, "picture": picture,
595	-	t.Errorf("%s: %v (run with -update to create it)", name, err)	649	+	"client2": client2, "badWindow": base \| 0x7777, "badRegion": base \| 0x8888,
596	-	return	650	+	"rootVisual": rootVisual, "rootColormap": binary.LittleEndian.Uint32(setup[screenOff+4:]), "rootFormat": format,
			651	+	"xfixesMajor": uint32(major), "xfixesEvent": uint32(xfixesEvent), "xfixesError": uint32(xfixesError),
			652	+	"resMajor": uint32(resMajor), "renderMajor": uint32(renderMajor),
			653	+	}
			654	+	if *update {
			655	+	for name, p := range out {
			656	+	writeGolden(t, name, p)
597		}	657		}
598	-	got := bytes.Clone(p)	658	+	rolesJSON, err := json.MarshalIndent(roles, "", " ")
599	-	if len(got) == len(want) {	659	+	if err != nil {
600	-	for _, r := range volatile[name] {	660	+	t.Fatal(err)
601	-	copy(got[r[0]:r[1]], want[r[0]:r[1]])
602	-	}
603		}	661		}
604	-	if !bytes.Equal(got, want) {	662	+	if err := os.WriteFile(rolesPath, append(rolesJSON, '\n'), 0644); err != nil {
605	-	t.Errorf("%s differs from live Xvfb:\n got %x\nwant %x", name, p, want)	663	+	t.Fatal(err)
606		}	664		}
607		return	665		return
608		}	666		}
			667	+	rolesJSON, err := os.ReadFile(rolesPath)
			668	+	if err != nil {
			669	+	t.Fatal(err)
			670	+	}
			671	+	var capturedRoles map[string]uint32
			672	+	if err := json.Unmarshal(rolesJSON, &capturedRoles); err != nil {
			673	+	t.Fatal(err)
			674	+	}
			675	+	for _, role := range slices.Sorted(maps.Keys(roles)) {
			676	+	if roles[role] != capturedRoles[role] {
			677	+	t.Logf("server-chosen %s: live %#x, golden %#x", role, roles[role], capturedRoles[role])
			678	+	}
			679	+	}
			680	+	for name, p := range out {
			681	+	compareGolden(t, name, p, roles, capturedRoles)
			682	+	}
			683	+	}
			684	+
			685	+	var sources = map[string]string{
			686	+	"req": "# source: Xvfb via raw socketpair tee; independent reference encoder; server accepted\n",
			687	+	"reply": "# source: Xvfb reply via raw socketpair tee to an independent reference request\n",
			688	+	"event": "# source: Xvfb event via raw socketpair tee; triggered by an independent second client or reference request\n",
			689	+	"error": "# source: Xvfb error via raw socketpair tee to an independent reference request\n",
			690	+	}
			691	+
			692	+	func writeGolden(t *testing.T, name string, p []byte) {
			693	+	t.Helper()
			694	+	path := filepath.Join("../../testdata/golden", name+".hex")
609		if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {	695		if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
610		t.Fatal(err)	696		t.Fatal(err)
611		}	697		}
			698	+	source := sources[name[strings.LastIndexByte(name, '.')+1:]]
612		text := source + "# xtrace fallback: local xtrace is glibc's execution tracer, not X11 xtrace\n" + hex.EncodeToString(p) + "\n"	699		text := source + "# xtrace fallback: local xtrace is glibc's execution tracer, not X11 xtrace\n" + hex.EncodeToString(p) + "\n"
613		if err := os.WriteFile(path, []byte(text), 0644); err != nil {	700		if err := os.WriteFile(path, []byte(text), 0644); err != nil {
614		t.Fatal(err)	701		t.Fatal(err)
615		}	702		}
616		}	703		}
			704	+
			705	+	// compareGolden checks a live packet against the committed golden without
			706	+	// depending on the server build: server-chosen fields must hold each side's
			707	+	// own value (live roles, recorded roles) and are masked before an exact
			708	+	// comparison; structural replies are checked for invariants only.
			709	+	func compareGolden(t *testing.T, name string, live []byte, roles, recorded map[string]uint32) {
			710	+	t.Helper()
			711	+	want, err := LoadHex(filepath.Join("../../testdata/golden", name+".hex"))
			712	+	if err != nil {
			713	+	t.Errorf("%s: %v (run with -update to create it)", name, err)
			714	+	return
			715	+	}
			716	+	if check := structural[name]; check != nil {
			717	+	if err := check(live, roles); err != nil {
			718	+	t.Errorf("%s (live): %v", name, err)
			719	+	}
			720	+	if err := check(want, recorded); err != nil {
			721	+	t.Errorf("%s (golden): %v", name, err)
			722	+	}
			723	+	return
			724	+	}
			725	+	got, exp, err := normalize(name, live, roles), normalize(name, want, recorded), error(nil)
			726	+	for _, e := range []struct {
			727	+	side string
			728	+	err error
			729	+	}{{"live", got.err}, {"golden", exp.err}} {
			730	+	if e.err != nil {
			731	+	t.Errorf("%s (%s): %v", name, e.side, e.err)
			732	+	err = e.err
			733	+	}
			734	+	}
			735	+	if err == nil && !bytes.Equal(got.b, exp.b) {
			736	+	t.Errorf("%s differs from live Xvfb after masking server-chosen fields:\n got %x\nwant %x", name, live, want)
			737	+	}
			738	+	}
			739	+
			740	+	type normalized struct {
			741	+	b []byte
			742	+	err error
			743	+	}
			744	+
			745	+	// normalize verifies each server-chosen field of p holds roles[Role] and
			746	+	// replaces it with zero bytes.
			747	+	func normalize(name string, p []byte, roles map[string]uint32) normalized {
			748	+	b := bytes.Clone(p)
			749	+	for _, f := range serverFields[name] {
			750	+	if f.Off+f.Size > len(b) {
			751	+	return normalized{err: fmt.Errorf("field %s at %d beyond %d bytes", f.Role, f.Off, len(b))}
			752	+	}
			753	+	if f.Role != "time" {
			754	+	v, ok := roles[f.Role]
			755	+	if !ok {
			756	+	return normalized{err: fmt.Errorf("no recorded value for role %s", f.Role)}
			757	+	}
			758	+	var got uint32
			759	+	if f.Size == 1 {
			760	+	got = uint32(b[f.Off])
			761	+	} else {
			762	+	got = binary.LittleEndian.Uint32(b[f.Off:])
			763	+	}
			764	+	if got != v {
			765	+	return normalized{err: fmt.Errorf("field %s at %d = %#x, want %#x", f.Role, f.Off, got, v)}
			766	+	}
			767	+	}
			768	+	clear(b[f.Off : f.Off+f.Size])
			769	+	}
			770	+	return normalized{b: b}
			771	+	}
			772	+
			773	+	// checkListExtensions: a framed reply whose STR list holds exactly names_len
			774	+	// entries filling the reply, including the extensions xturbo binds.
			775	+	func checkListExtensions(p []byte, _ map[string]uint32) error {
			776	+	if len(p) < 32 \|\| p[0] != 1 \|\| len(p) != 32+4*int(binary.LittleEndian.Uint32(p[4:])) {
			777	+	return fmt.Errorf("bad framing")
			778	+	}
			779	+	names := map[string]bool{}
			780	+	off := 32
			781	+	for range int(p[1]) {
			782	+	if off >= len(p) \|\| off+1+int(p[off]) > len(p) {
			783	+	return fmt.Errorf("STR list overruns the reply")
			784	+	}
			785	+	names[string(p[off+1:off+1+int(p[off])])] = true
			786	+	off += 1 + int(p[off])
			787	+	}
			788	+	if (off+3)&^3 != len(p) {
			789	+	return fmt.Errorf("STR list ends at %d, reply has %d bytes", off, len(p))
			790	+	}
			791	+	for _, want := range []string{"BIG-REQUESTS", "XC-MISC", "XFIXES", "RENDER", "SHAPE", "Composite", "X-Resource", "Generic Event Extension"} {
			792	+	if !names[want] {
			793	+	return fmt.Errorf("missing extension %q", want)
			794	+	}
			795	+	}
			796	+	return nil
			797	+	}
			798	+
			799	+	// checkQueryPictFormats: declared counts match the list sizes exactly and the
			800	+	// root visual maps to the picture format CreatePicture used.
			801	+	func checkQueryPictFormats(p []byte, roles map[string]uint32) error {
			802	+	u32 := binary.LittleEndian.Uint32
			803	+	if len(p) < 32 \|\| p[0] != 1 \|\| len(p) != 32+4*int(u32(p[4:])) {
			804	+	return fmt.Errorf("bad framing")
			805	+	}
			806	+	formats, screens, subpixels := int(u32(p[8:])), int(u32(p[12:])), int(u32(p[24:]))
			807	+	off := 32 + 28*formats
			808	+	found := false
			809	+	for range screens {
			810	+	if off+8 > len(p) {
			811	+	return fmt.Errorf("screens overrun")
			812	+	}
			813	+	depths := int(u32(p[off:]))
			814	+	off += 8
			815	+	for range depths {
			816	+	if off+8 > len(p) {
			817	+	return fmt.Errorf("depths overrun")
			818	+	}
			819	+	visuals := int(binary.LittleEndian.Uint16(p[off+2:]))
			820	+	off += 8
			821	+	for range visuals {
			822	+	if off+8 > len(p) {
			823	+	return fmt.Errorf("visuals overrun")
			824	+	}
			825	+	if u32(p[off:]) == roles["rootVisual"] && u32(p[off+4:]) == roles["rootFormat"] {
			826	+	found = true
			827	+	}
			828	+	off += 8
			829	+	}
			830	+	}
			831	+	}
			832	+	off += 4 * subpixels
			833	+	if off != len(p) {
			834	+	return fmt.Errorf("lists end at %d, reply has %d bytes", off, len(p))
			835	+	}
			836	+	if !found {
			837	+	return fmt.Errorf("root visual %#x does not map to format %#x", roles["rootVisual"], roles["rootFormat"])
			838	+	}
			839	+	return nil
			840	+	}

A testdata/golden/xvfb-roles.json +19 -0

@@ -0,0 +1,19 @@
	1	+	{
	2	+	"atom": 231,
	3	+	"badRegion": 2132104,
	4	+	"badWindow": 2127735,
	5	+	"base": 2097152,
	6	+	"child": 2097153,
	7	+	"client2": 4194305,
	8	+	"picture": 2097155,
	9	+	"renderMajor": 139,
	10	+	"resMajor": 148,
	11	+	"root": 927,
	12	+	"rootColormap": 32,
	13	+	"rootFormat": 41,
	14	+	"rootVisual": 33,
	15	+	"sibling": 2097154,
	16	+	"xfixesError": 140,
	17	+	"xfixesEvent": 87,
	18	+	"xfixesMajor": 138
	19	+	}

@@ -0,0 +1,19 @@
	1	+	{
	2	+	"atom": 231,
	3	+	"badRegion": 2132104,
	4	+	"badWindow": 2127735,
	5	+	"base": 2097152,
	6	+	"child": 2097153,
	7	+	"client2": 4194305,
	8	+	"picture": 2097155,
	9	+	"renderMajor": 139,
	10	+	"resMajor": 148,
	11	+	"root": 927,
	12	+	"rootColormap": 32,
	13	+	"rootFormat": 41,
	14	+	"rootVisual": 33,
	15	+	"sibling": 2097154,
	16	+	"xfixesError": 140,
	17	+	"xfixesEvent": 87,
	18	+	"xfixesMajor": 138
	19	+	}