src/syscall/syscall_unix_test.go - go - Git at Google

 // Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
 // +build aix darwin dragonfly freebsd linux netbsd openbsd solaris

 package syscall_test

 import (
 	"flag"
 	"fmt"
 	"internal/testenv"
 	"io"
 	"net"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strconv"
 	"syscall"
 	"testing"
 	"time"
 )

 // Tests that below functions, structures and constants are consistent
 // on all Unix-like systems.
 func _() {
 	// program scheduling priority functions and constants
 	var (
 		_ func(int, int, int) error   = syscall.Setpriority
 		_ func(int, int) (int, error) = syscall.Getpriority
 	)
 	const (
 		_ int = syscall.PRIO_USER
 		_ int = syscall.PRIO_PROCESS
 		_ int = syscall.PRIO_PGRP
 	)

 	// termios constants
 	const (
 		_ int = syscall.TCIFLUSH
 		_ int = syscall.TCIOFLUSH
 		_ int = syscall.TCOFLUSH
 	)

 	// fcntl file locking structure and constants
 	var (
 		_ = syscall.Flock_t{
 			Type:   int16(0),
 			Whence: int16(0),
 			Start:  int64(0),
 			Len:    int64(0),
 			Pid:    int32(0),
 		}
 	)
 	const (
 		_ = syscall.F_GETLK
 		_ = syscall.F_SETLK
 		_ = syscall.F_SETLKW
 	)
 }

 // TestFcntlFlock tests whether the file locking structure matches
 // the calling convention of each kernel.
 // On some Linux systems, glibc uses another set of values for the
 // commands and translates them to the correct value that the kernel
 // expects just before the actual fcntl syscall. As Go uses raw
 // syscalls directly, it must use the real value, not the glibc value.
 // Thus this test also verifies that the Flock_t structure can be
 // roundtripped with F_SETLK and F_GETLK.
 func TestFcntlFlock(t *testing.T) {
 	if runtime.GOOS == "ios" {
 		t.Skip("skipping; no child processes allowed on iOS")
 	}
 	flock := syscall.Flock_t{
 		Type:  syscall.F_WRLCK,
 		Start: 31415, Len: 271828, Whence: 1,
 	}
 	if os.Getenv("GO_WANT_HELPER_PROCESS") == "" {
 		// parent
 		tempDir := t.TempDir()
 		name := filepath.Join(tempDir, "TestFcntlFlock")
 		fd, err := syscall.Open(name, syscall.O_CREAT|syscall.O_RDWR|syscall.O_CLOEXEC, 0)
 		if err != nil {
 			t.Fatalf("Open failed: %v", err)
 		}
 		defer syscall.Close(fd)
 		if err := syscall.Ftruncate(fd, 1<<20); err != nil {
 			t.Fatalf("Ftruncate(1<<20) failed: %v", err)
 		}
 		if err := syscall.FcntlFlock(uintptr(fd), syscall.F_SETLK, &flock); err != nil {
 			t.Fatalf("FcntlFlock(F_SETLK) failed: %v", err)
 		}
 		cmd := exec.Command(os.Args[0], "-test.run=^TestFcntlFlock$")
 		cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
 		cmd.ExtraFiles = []*os.File{os.NewFile(uintptr(fd), name)}
 		out, err := cmd.CombinedOutput()
 		if len(out) > 0 || err != nil {
 			t.Fatalf("child process: %q, %v", out, err)
 		}
 	} else {
 		// child
 		got := flock
 		// make sure the child lock is conflicting with the parent lock
 		got.Start--
 		got.Len++
 		if err := syscall.FcntlFlock(3, syscall.F_GETLK, &got); err != nil {
 			t.Fatalf("FcntlFlock(F_GETLK) failed: %v", err)
 		}
 		flock.Pid = int32(syscall.Getppid())
 		// Linux kernel always set Whence to 0
 		flock.Whence = 0
 		if got.Type == flock.Type && got.Start == flock.Start && got.Len == flock.Len && got.Pid == flock.Pid && got.Whence == flock.Whence {
 			os.Exit(0)
 		}
 		t.Fatalf("FcntlFlock got %v, want %v", got, flock)
 	}
 }

 // TestPassFD tests passing a file descriptor over a Unix socket.
 //
 // This test involved both a parent and child process. The parent
 // process is invoked as a normal test, with "go test", which then
 // runs the child process by running the current test binary with args
 // "-test.run=^TestPassFD$" and an environment variable used to signal
 // that the test should become the child process instead.
 func TestPassFD(t *testing.T) {
 	testenv.MustHaveExec(t)

 	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
 		passFDChild()
 		return
 	}

 	if runtime.GOOS == "aix" {
 		// Unix network isn't properly working on AIX 7.2 with Technical Level < 2
 		out, err := exec.Command("oslevel", "-s").Output()
 		if err != nil {
 			t.Skipf("skipping on AIX because oslevel -s failed: %v", err)
 		}
 		if len(out) < len("7200-XX-ZZ-YYMM") { // AIX 7.2, Tech Level XX, Service Pack ZZ, date YYMM
 			t.Skip("skipping on AIX because oslevel -s hasn't the right length")
 		}
 		aixVer := string(out[:4])
 		tl, err := strconv.Atoi(string(out[5:7]))
 		if err != nil {
 			t.Skipf("skipping on AIX because oslevel -s output cannot be parsed: %v", err)
 		}
 		if aixVer < "7200" || (aixVer == "7200" && tl < 2) {
 			t.Skip("skipped on AIX versions previous to 7.2 TL 2")
 		}

 	}

 	tempDir := t.TempDir()

 	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
 	if err != nil {
 		t.Fatalf("Socketpair: %v", err)
 	}
 	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
 	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
 	defer writeFile.Close()
 	defer readFile.Close()

 	cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
 	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
 	cmd.ExtraFiles = []*os.File{writeFile}

 	out, err := cmd.CombinedOutput()
 	if len(out) > 0 || err != nil {
 		t.Fatalf("child process: %q, %v", out, err)
 	}

 	c, err := net.FileConn(readFile)
 	if err != nil {
 		t.Fatalf("FileConn: %v", err)
 	}
 	defer c.Close()

 	uc, ok := c.(*net.UnixConn)
 	if !ok {
 		t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
 	}

 	buf := make([]byte, 32) // expect 1 byte
 	oob := make([]byte, 32) // expect 24 bytes
 	closeUnix := time.AfterFunc(5*time.Second, func() {
 		t.Logf("timeout reading from unix socket")
 		uc.Close()
 	})
 	_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
 	if err != nil {
 		t.Fatalf("ReadMsgUnix: %v", err)
 	}
 	closeUnix.Stop()

 	scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
 	if err != nil {
 		t.Fatalf("ParseSocketControlMessage: %v", err)
 	}
 	if len(scms) != 1 {
 		t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
 	}
 	scm := scms[0]
 	gotFds, err := syscall.ParseUnixRights(&scm)
 	if err != nil {
 		t.Fatalf("syscall.ParseUnixRights: %v", err)
 	}
 	if len(gotFds) != 1 {
 		t.Fatalf("wanted 1 fd; got %#v", gotFds)
 	}

 	f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
 	defer f.Close()

 	got, err := io.ReadAll(f)
 	want := "Hello from child process!\n"
 	if string(got) != want {
 		t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
 	}
 }

 // passFDChild is the child process used by TestPassFD.
 func passFDChild() {
 	defer os.Exit(0)

 	// Look for our fd. It should be fd 3, but we work around an fd leak
 	// bug here (https://golang.org/issue/2603) to let it be elsewhere.
 	var uc *net.UnixConn
 	for fd := uintptr(3); fd <= 10; fd++ {
 		f := os.NewFile(fd, "unix-conn")
 		var ok bool
 		netc, _ := net.FileConn(f)
 		uc, ok = netc.(*net.UnixConn)
 		if ok {
 			break
 		}
 	}
 	if uc == nil {
 		fmt.Println("failed to find unix fd")
 		return
 	}

 	// Make a file f to send to our parent process on uc.
 	// We make it in tempDir, which our parent will clean up.
 	flag.Parse()
 	tempDir := flag.Arg(0)
 	f, err := os.CreateTemp(tempDir, "")
 	if err != nil {
 		fmt.Printf("TempFile: %v", err)
 		return
 	}

 	f.Write([]byte("Hello from child process!\n"))
 	f.Seek(0, io.SeekStart)

 	rights := syscall.UnixRights(int(f.Fd()))
 	dummyByte := []byte("x")
 	n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
 	if err != nil {
 		fmt.Printf("WriteMsgUnix: %v", err)
 		return
 	}
 	if n != 1 || oobn != len(rights) {
 		fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
 		return
 	}
 }

 // TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage,
 // and ParseUnixRights are able to successfully round-trip lists of file descriptors.
 func TestUnixRightsRoundtrip(t *testing.T) {
 	testCases := [...][][]int{
 		{{42}},
 		{{1, 2}},
 		{{3, 4, 5}},
 		{{}},
 		{{1, 2}, {3, 4, 5}, {}, {7}},
 	}
 	for _, testCase := range testCases {
 		b := []byte{}
 		var n int
 		for _, fds := range testCase {
 			// Last assignment to n wins
 			n = len(b) + syscall.CmsgLen(4*len(fds))
 			b = append(b, syscall.UnixRights(fds...)...)
 		}
 		// Truncate b
 		b = b[:n]

 		scms, err := syscall.ParseSocketControlMessage(b)
 		if err != nil {
 			t.Fatalf("ParseSocketControlMessage: %v", err)
 		}
 		if len(scms) != len(testCase) {
 			t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
 		}
 		for i, scm := range scms {
 			gotFds, err := syscall.ParseUnixRights(&scm)
 			if err != nil {
 				t.Fatalf("ParseUnixRights: %v", err)
 			}
 			wantFds := testCase[i]
 			if len(gotFds) != len(wantFds) {
 				t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
 			}
 			for j, fd := range gotFds {
 				if fd != wantFds[j] {
 					t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
 				}
 			}
 		}
 	}
 }

 func TestRlimit(t *testing.T) {
 	var rlimit, zero syscall.Rlimit
 	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit)
 	if err != nil {
 		t.Fatalf("Getrlimit: save failed: %v", err)
 	}
 	if zero == rlimit {
 		t.Fatalf("Getrlimit: save failed: got zero value %#v", rlimit)
 	}
 	set := rlimit
 	set.Cur = set.Max - 1
 	if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && set.Cur > 4096 {
 		// rlim_min for RLIMIT_NOFILE should be equal to
 		// or lower than kern.maxfilesperproc, which on
 		// some machines are 4096. See #40564.
 		set.Cur = 4096
 	}
 	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &set)
 	if err != nil {
 		t.Fatalf("Setrlimit: set failed: %#v %v", set, err)
 	}
 	var get syscall.Rlimit
 	err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &get)
 	if err != nil {
 		t.Fatalf("Getrlimit: get failed: %v", err)
 	}
 	set = rlimit
 	set.Cur = set.Max - 1
 	if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && set.Cur > 4096 {
 		set.Cur = 4096
 	}
 	if set != get {
 		t.Fatalf("Rlimit: change failed: wanted %#v got %#v", set, get)
 	}
 	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit)
 	if err != nil {
 		t.Fatalf("Setrlimit: restore failed: %#v %v", rlimit, err)
 	}
 }

 func TestSeekFailure(t *testing.T) {
 	_, err := syscall.Seek(-1, 0, io.SeekStart)
 	if err == nil {
 		t.Fatalf("Seek(-1, 0, 0) did not fail")
 	}
 	str := err.Error() // used to crash on Linux
 	t.Logf("Seek: %v", str)
 	if str == "" {
 		t.Fatalf("Seek(-1, 0, 0) return error with empty message")
 	}
 }

 func TestSetsockoptString(t *testing.T) {
 	// should not panic on empty string, see issue #31277
 	err := syscall.SetsockoptString(-1, 0, 0, "")
 	if err == nil {
 		t.Fatalf("SetsockoptString: did not fail")
 	}
 }

 func TestENFILETemporary(t *testing.T) {
 	if !syscall.ENFILE.Temporary() {
 		t.Error("ENFILE is not treated as a temporary error")
 	}
 }
	// Copyright 2013 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	//go:build aix \|\| darwin \|\| dragonfly \|\| freebsd \|\| linux \|\| netbsd \|\| openbsd \|\| solaris
	// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris

	package syscall_test

	import (
	"flag"
	"fmt"
	"internal/testenv"
	"io"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"syscall"
	"testing"
	"time"
	)

	// Tests that below functions, structures and constants are consistent
	// on all Unix-like systems.
	func _() {
	// program scheduling priority functions and constants
	var (
	_ func(int, int, int) error = syscall.Setpriority
	_ func(int, int) (int, error) = syscall.Getpriority
	)
	const (
	_ int = syscall.PRIO_USER
	_ int = syscall.PRIO_PROCESS
	_ int = syscall.PRIO_PGRP
	)

	// termios constants
	const (
	_ int = syscall.TCIFLUSH
	_ int = syscall.TCIOFLUSH
	_ int = syscall.TCOFLUSH
	)

	// fcntl file locking structure and constants
	var (
	_ = syscall.Flock_t{
	Type: int16(0),
	Whence: int16(0),
	Start: int64(0),
	Len: int64(0),
	Pid: int32(0),
	}
	)
	const (
	_ = syscall.F_GETLK
	_ = syscall.F_SETLK
	_ = syscall.F_SETLKW
	)
	}

	// TestFcntlFlock tests whether the file locking structure matches
	// the calling convention of each kernel.
	// On some Linux systems, glibc uses another set of values for the
	// commands and translates them to the correct value that the kernel
	// expects just before the actual fcntl syscall. As Go uses raw
	// syscalls directly, it must use the real value, not the glibc value.
	// Thus this test also verifies that the Flock_t structure can be
	// roundtripped with F_SETLK and F_GETLK.
	func TestFcntlFlock(t *testing.T) {
	if runtime.GOOS == "ios" {
	t.Skip("skipping; no child processes allowed on iOS")
	}
	flock := syscall.Flock_t{
	Type: syscall.F_WRLCK,
	Start: 31415, Len: 271828, Whence: 1,
	}
	if os.Getenv("GO_WANT_HELPER_PROCESS") == "" {
	// parent
	tempDir := t.TempDir()
	name := filepath.Join(tempDir, "TestFcntlFlock")
	fd, err := syscall.Open(name, syscall.O_CREAT\|syscall.O_RDWR\|syscall.O_CLOEXEC, 0)
	if err != nil {
	t.Fatalf("Open failed: %v", err)
	}
	defer syscall.Close(fd)
	if err := syscall.Ftruncate(fd, 1<<20); err != nil {
	t.Fatalf("Ftruncate(1<<20) failed: %v", err)
	}
	if err := syscall.FcntlFlock(uintptr(fd), syscall.F_SETLK, &flock); err != nil {
	t.Fatalf("FcntlFlock(F_SETLK) failed: %v", err)
	}
	cmd := exec.Command(os.Args[0], "-test.run=^TestFcntlFlock$")
	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
	cmd.ExtraFiles = []*os.File{os.NewFile(uintptr(fd), name)}
	out, err := cmd.CombinedOutput()
	if len(out) > 0 \|\| err != nil {
	t.Fatalf("child process: %q, %v", out, err)
	}
	} else {
	// child
	got := flock
	// make sure the child lock is conflicting with the parent lock
	got.Start--
	got.Len++
	if err := syscall.FcntlFlock(3, syscall.F_GETLK, &got); err != nil {
	t.Fatalf("FcntlFlock(F_GETLK) failed: %v", err)
	}
	flock.Pid = int32(syscall.Getppid())
	// Linux kernel always set Whence to 0
	flock.Whence = 0
	if got.Type == flock.Type && got.Start == flock.Start && got.Len == flock.Len && got.Pid == flock.Pid && got.Whence == flock.Whence {
	os.Exit(0)
	}
	t.Fatalf("FcntlFlock got %v, want %v", got, flock)
	}
	}

	// TestPassFD tests passing a file descriptor over a Unix socket.
	//
	// This test involved both a parent and child process. The parent
	// process is invoked as a normal test, with "go test", which then
	// runs the child process by running the current test binary with args
	// "-test.run=^TestPassFD$" and an environment variable used to signal
	// that the test should become the child process instead.
	func TestPassFD(t *testing.T) {
	testenv.MustHaveExec(t)

	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
	passFDChild()
	return
	}

	if runtime.GOOS == "aix" {
	// Unix network isn't properly working on AIX 7.2 with Technical Level < 2
	out, err := exec.Command("oslevel", "-s").Output()
	if err != nil {
	t.Skipf("skipping on AIX because oslevel -s failed: %v", err)
	}
	if len(out) < len("7200-XX-ZZ-YYMM") { // AIX 7.2, Tech Level XX, Service Pack ZZ, date YYMM
	t.Skip("skipping on AIX because oslevel -s hasn't the right length")
	}
	aixVer := string(out[:4])
	tl, err := strconv.Atoi(string(out[5:7]))
	if err != nil {
	t.Skipf("skipping on AIX because oslevel -s output cannot be parsed: %v", err)
	}
	if aixVer < "7200" \|\| (aixVer == "7200" && tl < 2) {
	t.Skip("skipped on AIX versions previous to 7.2 TL 2")
	}

	}

	tempDir := t.TempDir()

	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
	if err != nil {
	t.Fatalf("Socketpair: %v", err)
	}
	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
	defer writeFile.Close()
	defer readFile.Close()

	cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
	cmd.ExtraFiles = []*os.File{writeFile}

	out, err := cmd.CombinedOutput()
	if len(out) > 0 \|\| err != nil {
	t.Fatalf("child process: %q, %v", out, err)
	}

	c, err := net.FileConn(readFile)
	if err != nil {
	t.Fatalf("FileConn: %v", err)
	}
	defer c.Close()

	uc, ok := c.(*net.UnixConn)
	if !ok {
	t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
	}

	buf := make([]byte, 32) // expect 1 byte
	oob := make([]byte, 32) // expect 24 bytes
	closeUnix := time.AfterFunc(5*time.Second, func() {
	t.Logf("timeout reading from unix socket")
	uc.Close()
	})
	_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
	if err != nil {
	t.Fatalf("ReadMsgUnix: %v", err)
	}
	closeUnix.Stop()

	scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
	if err != nil {
	t.Fatalf("ParseSocketControlMessage: %v", err)
	}
	if len(scms) != 1 {
	t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
	}
	scm := scms[0]
	gotFds, err := syscall.ParseUnixRights(&scm)
	if err != nil {
	t.Fatalf("syscall.ParseUnixRights: %v", err)
	}
	if len(gotFds) != 1 {
	t.Fatalf("wanted 1 fd; got %#v", gotFds)
	}

	f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
	defer f.Close()

	got, err := io.ReadAll(f)
	want := "Hello from child process!\n"
	if string(got) != want {
	t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
	}
	}

	// passFDChild is the child process used by TestPassFD.
	func passFDChild() {
	defer os.Exit(0)

	// Look for our fd. It should be fd 3, but we work around an fd leak
	// bug here (https://golang.org/issue/2603) to let it be elsewhere.
	var uc *net.UnixConn
	for fd := uintptr(3); fd <= 10; fd++ {
	f := os.NewFile(fd, "unix-conn")
	var ok bool
	netc, _ := net.FileConn(f)
	uc, ok = netc.(*net.UnixConn)
	if ok {
	break
	}
	}
	if uc == nil {
	fmt.Println("failed to find unix fd")
	return
	}

	// Make a file f to send to our parent process on uc.
	// We make it in tempDir, which our parent will clean up.
	flag.Parse()
	tempDir := flag.Arg(0)
	f, err := os.CreateTemp(tempDir, "")
	if err != nil {
	fmt.Printf("TempFile: %v", err)
	return
	}

	f.Write([]byte("Hello from child process!\n"))
	f.Seek(0, io.SeekStart)

	rights := syscall.UnixRights(int(f.Fd()))
	dummyByte := []byte("x")
	n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
	if err != nil {
	fmt.Printf("WriteMsgUnix: %v", err)
	return
	}
	if n != 1 \|\| oobn != len(rights) {
	fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
	return
	}
	}

	// TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage,
	// and ParseUnixRights are able to successfully round-trip lists of file descriptors.
	func TestUnixRightsRoundtrip(t *testing.T) {
	testCases := [...][][]int{
	{{42}},
	{{1, 2}},
	{{3, 4, 5}},
	{{}},
	{{1, 2}, {3, 4, 5}, {}, {7}},
	}
	for _, testCase := range testCases {
	b := []byte{}
	var n int
	for _, fds := range testCase {
	// Last assignment to n wins
	n = len(b) + syscall.CmsgLen(4*len(fds))
	b = append(b, syscall.UnixRights(fds...)...)
	}
	// Truncate b
	b = b[:n]

	scms, err := syscall.ParseSocketControlMessage(b)
	if err != nil {
	t.Fatalf("ParseSocketControlMessage: %v", err)
	}
	if len(scms) != len(testCase) {
	t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
	}
	for i, scm := range scms {
	gotFds, err := syscall.ParseUnixRights(&scm)
	if err != nil {
	t.Fatalf("ParseUnixRights: %v", err)
	}
	wantFds := testCase[i]
	if len(gotFds) != len(wantFds) {
	t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
	}
	for j, fd := range gotFds {
	if fd != wantFds[j] {
	t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
	}
	}
	}
	}
	}

	func TestRlimit(t *testing.T) {
	var rlimit, zero syscall.Rlimit
	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit)
	if err != nil {
	t.Fatalf("Getrlimit: save failed: %v", err)
	}
	if zero == rlimit {
	t.Fatalf("Getrlimit: save failed: got zero value %#v", rlimit)
	}
	set := rlimit
	set.Cur = set.Max - 1
	if (runtime.GOOS == "darwin" \|\| runtime.GOOS == "ios") && set.Cur > 4096 {
	// rlim_min for RLIMIT_NOFILE should be equal to
	// or lower than kern.maxfilesperproc, which on
	// some machines are 4096. See #40564.
	set.Cur = 4096
	}
	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &set)
	if err != nil {
	t.Fatalf("Setrlimit: set failed: %#v %v", set, err)
	}
	var get syscall.Rlimit
	err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &get)
	if err != nil {
	t.Fatalf("Getrlimit: get failed: %v", err)
	}
	set = rlimit
	set.Cur = set.Max - 1
	if (runtime.GOOS == "darwin" \|\| runtime.GOOS == "ios") && set.Cur > 4096 {
	set.Cur = 4096
	}
	if set != get {
	t.Fatalf("Rlimit: change failed: wanted %#v got %#v", set, get)
	}
	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit)
	if err != nil {
	t.Fatalf("Setrlimit: restore failed: %#v %v", rlimit, err)
	}
	}

	func TestSeekFailure(t *testing.T) {
	_, err := syscall.Seek(-1, 0, io.SeekStart)
	if err == nil {
	t.Fatalf("Seek(-1, 0, 0) did not fail")
	}
	str := err.Error() // used to crash on Linux
	t.Logf("Seek: %v", str)
	if str == "" {
	t.Fatalf("Seek(-1, 0, 0) return error with empty message")
	}
	}

	func TestSetsockoptString(t *testing.T) {
	// should not panic on empty string, see issue #31277
	err := syscall.SetsockoptString(-1, 0, 0, "")
	if err == nil {
	t.Fatalf("SetsockoptString: did not fail")
	}
	}

	func TestENFILETemporary(t *testing.T) {
	if !syscall.ENFILE.Temporary() {
	t.Error("ENFILE is not treated as a temporary error")
	}
	}