Source file src/golang.org/x/sys/unix/syscall_unix_test.go

Documentation: golang.org/x/sys/unix

     1  // Copyright 2013 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
     6  
     7  package unix_test
     8  
     9  import (
    10  	"bytes"
    11  	"flag"
    12  	"fmt"
    13  	"io"
    14  	"net"
    15  	"os"
    16  	"os/exec"
    17  	"path/filepath"
    18  	"reflect"
    19  	"runtime"
    20  	"strconv"
    21  	"sync"
    22  	"syscall"
    23  	"testing"
    24  	"time"
    25  
    26  	"golang.org/x/sys/unix"
    27  )
    28  
    29  // Tests that below functions, structures and constants are consistent
    30  // on all Unix-like systems.
    31  func _() {
    32  	// program scheduling priority functions and constants
    33  	var (
    34  		_ func(int, int, int) error   = unix.Setpriority
    35  		_ func(int, int) (int, error) = unix.Getpriority
    36  	)
    37  	const (
    38  		_ int = unix.PRIO_USER
    39  		_ int = unix.PRIO_PROCESS
    40  		_ int = unix.PRIO_PGRP
    41  	)
    42  
    43  	// termios constants
    44  	const (
    45  		_ int = unix.TCIFLUSH
    46  		_ int = unix.TCIOFLUSH
    47  		_ int = unix.TCOFLUSH
    48  	)
    49  
    50  	// fcntl file locking structure and constants
    51  	var (
    52  		_ = unix.Flock_t{
    53  			Type:   int16(0),
    54  			Whence: int16(0),
    55  			Start:  int64(0),
    56  			Len:    int64(0),
    57  			Pid:    int32(0),
    58  		}
    59  	)
    60  	const (
    61  		_ = unix.F_GETLK
    62  		_ = unix.F_SETLK
    63  		_ = unix.F_SETLKW
    64  	)
    65  }
    66  
    67  func TestErrnoSignalName(t *testing.T) {
    68  	testErrors := []struct {
    69  		num  syscall.Errno
    70  		name string
    71  	}{
    72  		{syscall.EPERM, "EPERM"},
    73  		{syscall.EINVAL, "EINVAL"},
    74  		{syscall.ENOENT, "ENOENT"},
    75  	}
    76  
    77  	for _, te := range testErrors {
    78  		t.Run(fmt.Sprintf("%d/%s", te.num, te.name), func(t *testing.T) {
    79  			e := unix.ErrnoName(te.num)
    80  			if e != te.name {
    81  				t.Errorf("ErrnoName(%d) returned %s, want %s", te.num, e, te.name)
    82  			}
    83  		})
    84  	}
    85  
    86  	testSignals := []struct {
    87  		num  syscall.Signal
    88  		name string
    89  	}{
    90  		{syscall.SIGHUP, "SIGHUP"},
    91  		{syscall.SIGPIPE, "SIGPIPE"},
    92  		{syscall.SIGSEGV, "SIGSEGV"},
    93  	}
    94  
    95  	for _, ts := range testSignals {
    96  		t.Run(fmt.Sprintf("%d/%s", ts.num, ts.name), func(t *testing.T) {
    97  			s := unix.SignalName(ts.num)
    98  			if s != ts.name {
    99  				t.Errorf("SignalName(%d) returned %s, want %s", ts.num, s, ts.name)
   100  			}
   101  		})
   102  	}
   103  }
   104  
   105  func TestSignalNum(t *testing.T) {
   106  	testSignals := []struct {
   107  		name string
   108  		want syscall.Signal
   109  	}{
   110  		{"SIGHUP", syscall.SIGHUP},
   111  		{"SIGPIPE", syscall.SIGPIPE},
   112  		{"SIGSEGV", syscall.SIGSEGV},
   113  		{"NONEXISTS", 0},
   114  	}
   115  	for _, ts := range testSignals {
   116  		t.Run(fmt.Sprintf("%s/%d", ts.name, ts.want), func(t *testing.T) {
   117  			got := unix.SignalNum(ts.name)
   118  			if got != ts.want {
   119  				t.Errorf("SignalNum(%s) returned %d, want %d", ts.name, got, ts.want)
   120  			}
   121  		})
   122  
   123  	}
   124  }
   125  
   126  func TestFcntlInt(t *testing.T) {
   127  	t.Parallel()
   128  	file, err := os.Create(filepath.Join(t.TempDir(), t.Name()))
   129  	if err != nil {
   130  		t.Fatal(err)
   131  	}
   132  	defer file.Close()
   133  	f := file.Fd()
   134  	flags, err := unix.FcntlInt(f, unix.F_GETFD, 0)
   135  	if err != nil {
   136  		t.Fatal(err)
   137  	}
   138  	if flags&unix.FD_CLOEXEC == 0 {
   139  		t.Errorf("flags %#x do not include FD_CLOEXEC", flags)
   140  	}
   141  }
   142  
   143  // TestFcntlFlock tests whether the file locking structure matches
   144  // the calling convention of each kernel.
   145  func TestFcntlFlock(t *testing.T) {
   146  	name := filepath.Join(t.TempDir(), "TestFcntlFlock")
   147  	fd, err := unix.Open(name, unix.O_CREAT|unix.O_RDWR|unix.O_CLOEXEC, 0)
   148  	if err != nil {
   149  		t.Fatalf("Open failed: %v", err)
   150  	}
   151  	defer unix.Close(fd)
   152  	flock := unix.Flock_t{
   153  		Type:  unix.F_RDLCK,
   154  		Start: 0, Len: 0, Whence: 1,
   155  	}
   156  	if err := unix.FcntlFlock(uintptr(fd), unix.F_GETLK, &flock); err != nil {
   157  		t.Fatalf("FcntlFlock failed: %v", err)
   158  	}
   159  }
   160  
   161  // TestPassFD tests passing a file descriptor over a Unix socket.
   162  //
   163  // This test involved both a parent and child process. The parent
   164  // process is invoked as a normal test, with "go test", which then
   165  // runs the child process by running the current test binary with args
   166  // "-test.run=^TestPassFD$" and an environment variable used to signal
   167  // that the test should become the child process instead.
   168  func TestPassFD(t *testing.T) {
   169  	if runtime.GOOS == "ios" {
   170  		t.Skip("cannot exec subprocess on iOS, skipping test")
   171  	}
   172  
   173  	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
   174  		passFDChild()
   175  		return
   176  	}
   177  
   178  	if runtime.GOOS == "aix" {
   179  		// Unix network isn't properly working on AIX
   180  		// 7.2 with Technical Level < 2
   181  		out, err := exec.Command("oslevel", "-s").Output()
   182  		if err != nil {
   183  			t.Skipf("skipping on AIX because oslevel -s failed: %v", err)
   184  		}
   185  
   186  		if len(out) < len("7200-XX-ZZ-YYMM") { // AIX 7.2, Tech Level XX, Service Pack ZZ, date YYMM
   187  			t.Skip("skipping on AIX because oslevel -s hasn't the right length")
   188  		}
   189  		aixVer := string(out[:4])
   190  		tl, err := strconv.Atoi(string(out[5:7]))
   191  		if err != nil {
   192  			t.Skipf("skipping on AIX because oslevel -s output cannot be parsed: %v", err)
   193  		}
   194  		if aixVer < "7200" || (aixVer == "7200" && tl < 2) {
   195  			t.Skip("skipped on AIX versions previous to 7.2 TL 2")
   196  		}
   197  	}
   198  
   199  	fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_STREAM, 0)
   200  	if err != nil {
   201  		t.Fatalf("Socketpair: %v", err)
   202  	}
   203  	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
   204  	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
   205  	defer writeFile.Close()
   206  	defer readFile.Close()
   207  
   208  	exe, err := os.Executable()
   209  	if err != nil {
   210  		t.Fatal(err)
   211  	}
   212  	cmd := exec.Command(exe, "-test.run=^TestPassFD$", "--", t.TempDir())
   213  	cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
   214  	if lp := os.Getenv("LD_LIBRARY_PATH"); lp != "" {
   215  		cmd.Env = append(cmd.Env, "LD_LIBRARY_PATH="+lp)
   216  	}
   217  	cmd.ExtraFiles = []*os.File{writeFile}
   218  
   219  	out, err := cmd.CombinedOutput()
   220  	if len(out) > 0 || err != nil {
   221  		t.Fatalf("child process: %q, %v", out, err)
   222  	}
   223  
   224  	c, err := net.FileConn(readFile)
   225  	if err != nil {
   226  		t.Fatalf("FileConn: %v", err)
   227  	}
   228  	defer c.Close()
   229  
   230  	uc, ok := c.(*net.UnixConn)
   231  	if !ok {
   232  		t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
   233  	}
   234  
   235  	buf := make([]byte, 32) // expect 1 byte
   236  	oob := make([]byte, 32) // expect 24 bytes
   237  	closeUnix := time.AfterFunc(5*time.Second, func() {
   238  		t.Logf("timeout reading from unix socket")
   239  		uc.Close()
   240  	})
   241  	_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
   242  	if err != nil {
   243  		t.Fatalf("ReadMsgUnix: %v", err)
   244  	}
   245  	closeUnix.Stop()
   246  
   247  	scms, err := unix.ParseSocketControlMessage(oob[:oobn])
   248  	if err != nil {
   249  		t.Fatalf("ParseSocketControlMessage: %v", err)
   250  	}
   251  	if len(scms) != 1 {
   252  		t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
   253  	}
   254  	scm := scms[0]
   255  	gotFds, err := unix.ParseUnixRights(&scm)
   256  	if err != nil {
   257  		t.Fatalf("unix.ParseUnixRights: %v", err)
   258  	}
   259  	if len(gotFds) != 1 {
   260  		t.Fatalf("wanted 1 fd; got %#v", gotFds)
   261  	}
   262  
   263  	f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
   264  	defer f.Close()
   265  
   266  	got, err := io.ReadAll(f)
   267  	want := "Hello from child process!\n"
   268  	if string(got) != want {
   269  		t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
   270  	}
   271  }
   272  
   273  // passFDChild is the child process used by TestPassFD.
   274  func passFDChild() {
   275  	defer os.Exit(0)
   276  
   277  	// Look for our fd. It should be fd 3, but we work around an fd leak
   278  	// bug here (http://golang.org/issue/2603) to let it be elsewhere.
   279  	var uc *net.UnixConn
   280  	for fd := uintptr(3); fd <= 10; fd++ {
   281  		f := os.NewFile(fd, "unix-conn")
   282  		var ok bool
   283  		netc, _ := net.FileConn(f)
   284  		uc, ok = netc.(*net.UnixConn)
   285  		if ok {
   286  			break
   287  		}
   288  	}
   289  	if uc == nil {
   290  		fmt.Println("failed to find unix fd")
   291  		return
   292  	}
   293  
   294  	// Make a file f to send to our parent process on uc.
   295  	// We make it in tempDir, which our parent will clean up.
   296  	flag.Parse()
   297  	tempDir := flag.Arg(0)
   298  	f, err := os.Create(filepath.Join(tempDir, "file"))
   299  	if err != nil {
   300  		fmt.Println(err)
   301  		return
   302  	}
   303  
   304  	f.Write([]byte("Hello from child process!\n"))
   305  	f.Seek(0, 0)
   306  
   307  	rights := unix.UnixRights(int(f.Fd()))
   308  	dummyByte := []byte("x")
   309  	n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
   310  	if err != nil {
   311  		fmt.Printf("WriteMsgUnix: %v", err)
   312  		return
   313  	}
   314  	if n != 1 || oobn != len(rights) {
   315  		fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
   316  		return
   317  	}
   318  }
   319  
   320  // TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage, ParseOneSocketControlMessage,
   321  // and ParseUnixRights are able to successfully round-trip lists of file descriptors.
   322  func TestUnixRightsRoundtrip(t *testing.T) {
   323  	testCases := [...][][]int{
   324  		{{42}},
   325  		{{1, 2}},
   326  		{{3, 4, 5}},
   327  		{{}},
   328  		{{1, 2}, {3, 4, 5}, {}, {7}},
   329  	}
   330  	for _, testCase := range testCases {
   331  		b := []byte{}
   332  		var n int
   333  		for _, fds := range testCase {
   334  			// Last assignment to n wins
   335  			n = len(b) + unix.CmsgLen(4*len(fds))
   336  			b = append(b, unix.UnixRights(fds...)...)
   337  		}
   338  		// Truncate b
   339  		b = b[:n]
   340  
   341  		scms, err := unix.ParseSocketControlMessage(b)
   342  		if err != nil {
   343  			t.Fatalf("ParseSocketControlMessage: %v", err)
   344  		}
   345  		if len(scms) != len(testCase) {
   346  			t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
   347  		}
   348  
   349  		var c int
   350  		for len(b) > 0 {
   351  			hdr, data, remainder, err := unix.ParseOneSocketControlMessage(b)
   352  			if err != nil {
   353  				t.Fatalf("ParseOneSocketControlMessage: %v", err)
   354  			}
   355  			if scms[c].Header != hdr || !bytes.Equal(scms[c].Data, data) {
   356  				t.Fatal("expected SocketControlMessage header and data to match")
   357  			}
   358  			b = remainder
   359  			c++
   360  		}
   361  		if c != len(scms) {
   362  			t.Fatalf("expected %d SocketControlMessages; got %d", len(scms), c)
   363  		}
   364  
   365  		for i, scm := range scms {
   366  			gotFds, err := unix.ParseUnixRights(&scm)
   367  			if err != nil {
   368  				t.Fatalf("ParseUnixRights: %v", err)
   369  			}
   370  			wantFds := testCase[i]
   371  			if len(gotFds) != len(wantFds) {
   372  				t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
   373  			}
   374  			for j, fd := range gotFds {
   375  				if fd != wantFds[j] {
   376  					t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
   377  				}
   378  			}
   379  		}
   380  	}
   381  }
   382  
   383  func TestRlimit(t *testing.T) {
   384  	var rlimit, zero unix.Rlimit
   385  	err := unix.Getrlimit(unix.RLIMIT_NOFILE, &rlimit)
   386  	if err != nil {
   387  		t.Fatalf("Getrlimit: save failed: %v", err)
   388  	}
   389  	if zero == rlimit {
   390  		t.Fatalf("Getrlimit: save failed: got zero value %#v", rlimit)
   391  	}
   392  	set := rlimit
   393  	set.Cur = set.Max - 1
   394  	if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && set.Cur > 4096 {
   395  		// rlim_min for RLIMIT_NOFILE should be equal to
   396  		// or lower than kern.maxfilesperproc, which on
   397  		// some machines are 4096. See #40564.
   398  		set.Cur = 4096
   399  	}
   400  	err = unix.Setrlimit(unix.RLIMIT_NOFILE, &set)
   401  	if err != nil {
   402  		t.Fatalf("Setrlimit: set failed: %#v %v", set, err)
   403  	}
   404  	var get unix.Rlimit
   405  	err = unix.Getrlimit(unix.RLIMIT_NOFILE, &get)
   406  	if err != nil {
   407  		t.Fatalf("Getrlimit: get failed: %v", err)
   408  	}
   409  	set = rlimit
   410  	set.Cur = set.Max - 1
   411  	if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && set.Cur > 4096 {
   412  		set.Cur = 4096
   413  	}
   414  	if set != get {
   415  		// Seems like Darwin requires some privilege to
   416  		// increase the soft limit of rlimit sandbox, though
   417  		// Setrlimit never reports an error.
   418  		switch runtime.GOOS {
   419  		case "darwin", "ios":
   420  		default:
   421  			t.Fatalf("Rlimit: change failed: wanted %#v got %#v", set, get)
   422  		}
   423  	}
   424  	err = unix.Setrlimit(unix.RLIMIT_NOFILE, &rlimit)
   425  	if err != nil {
   426  		t.Fatalf("Setrlimit: restore failed: %#v %v", rlimit, err)
   427  	}
   428  
   429  	// make sure RLIM_INFINITY can be assigned to Rlimit members
   430  	_ = unix.Rlimit{
   431  		Cur: unix.RLIM_INFINITY,
   432  		Max: unix.RLIM_INFINITY,
   433  	}
   434  }
   435  
   436  func TestSeekFailure(t *testing.T) {
   437  	_, err := unix.Seek(-1, 0, 0)
   438  	if err == nil {
   439  		t.Fatalf("Seek(-1, 0, 0) did not fail")
   440  	}
   441  	str := err.Error() // used to crash on Linux
   442  	t.Logf("Seek: %v", str)
   443  	if str == "" {
   444  		t.Fatalf("Seek(-1, 0, 0) return error with empty message")
   445  	}
   446  }
   447  
   448  func TestSetsockoptString(t *testing.T) {
   449  	// should not panic on empty string, see issue #31277
   450  	err := unix.SetsockoptString(-1, 0, 0, "")
   451  	if err == nil {
   452  		t.Fatalf("SetsockoptString: did not fail")
   453  	}
   454  }
   455  
   456  func TestDup(t *testing.T) {
   457  	file, err := os.Create(filepath.Join(t.TempDir(), t.Name()))
   458  	if err != nil {
   459  		t.Fatal(err)
   460  	}
   461  	defer file.Close()
   462  	f := int(file.Fd())
   463  
   464  	newFd, err := unix.Dup(f)
   465  	if err != nil {
   466  		t.Fatalf("Dup: %v", err)
   467  	}
   468  
   469  	// Create and reserve a file descriptor.
   470  	// Dup2 automatically closes it before reusing it.
   471  	nullFile, err := os.Open("/dev/null")
   472  	if err != nil {
   473  		t.Fatal(err)
   474  	}
   475  	dupFd := int(file.Fd())
   476  	err = unix.Dup2(newFd, dupFd)
   477  	if err != nil {
   478  		t.Fatalf("Dup2: %v", err)
   479  	}
   480  	// Keep the dummy file open long enough to not be closed in
   481  	// its finalizer.
   482  	runtime.KeepAlive(nullFile)
   483  
   484  	b1 := []byte("Test123")
   485  	b2 := make([]byte, 7)
   486  	_, err = unix.Write(dupFd, b1)
   487  	if err != nil {
   488  		t.Fatalf("Write to dup2 fd failed: %v", err)
   489  	}
   490  	_, err = unix.Seek(f, 0, 0)
   491  	if err != nil {
   492  		t.Fatalf("Seek failed: %v", err)
   493  	}
   494  	_, err = unix.Read(f, b2)
   495  	if err != nil {
   496  		t.Fatalf("Read back failed: %v", err)
   497  	}
   498  	if string(b1) != string(b2) {
   499  		t.Errorf("Dup: stdout write not in file, expected %v, got %v", string(b1), string(b2))
   500  	}
   501  }
   502  
   503  func TestPoll(t *testing.T) {
   504  	if runtime.GOOS == "android" || runtime.GOOS == "ios" {
   505  		t.Skip("mkfifo syscall is not available on android and iOS, skipping test")
   506  	}
   507  
   508  	chtmpdir(t)
   509  	f := mktmpfifo(t)
   510  
   511  	const timeout = 100
   512  
   513  	ok := make(chan bool, 1)
   514  	go func() {
   515  		select {
   516  		case <-time.After(10 * timeout * time.Millisecond):
   517  			t.Errorf("Poll: failed to timeout after %d milliseconds", 10*timeout)
   518  		case <-ok:
   519  		}
   520  	}()
   521  
   522  	for {
   523  		fds := []unix.PollFd{{Fd: int32(f.Fd()), Events: unix.POLLIN}}
   524  		n, err := unix.Poll(fds, timeout)
   525  		ok <- true
   526  		if err == unix.EINTR {
   527  			t.Logf("Poll interrupted")
   528  			continue
   529  		} else if err != nil {
   530  			t.Errorf("Poll: unexpected error: %v", err)
   531  			return
   532  		}
   533  		if n != 0 {
   534  			t.Errorf("Poll: wrong number of events: got %v, expected %v", n, 0)
   535  
   536  			// Identify which event(s) caused Poll to return.
   537  			// We can't trivially use a table here because Revents
   538  			// isn't the same type on all systems.
   539  			if fds[0].Revents&unix.POLLIN != 0 {
   540  				t.Log("found POLLIN event")
   541  			}
   542  			if fds[0].Revents&unix.POLLPRI != 0 {
   543  				t.Log("found POLLPRI event")
   544  			}
   545  			if fds[0].Revents&unix.POLLOUT != 0 {
   546  				t.Log("found POLLOUT event")
   547  			}
   548  			if fds[0].Revents&unix.POLLERR != 0 {
   549  				t.Log("found POLLERR event")
   550  			}
   551  			if fds[0].Revents&unix.POLLHUP != 0 {
   552  				t.Log("found POLLHUP event")
   553  			}
   554  			if fds[0].Revents&unix.POLLNVAL != 0 {
   555  				t.Log("found POLLNVAL event")
   556  			}
   557  		}
   558  		break
   559  	}
   560  }
   561  
   562  func TestSelect(t *testing.T) {
   563  	for {
   564  		n, err := unix.Select(0, nil, nil, nil, &unix.Timeval{Sec: 0, Usec: 0})
   565  		if err == unix.EINTR {
   566  			t.Logf("Select interrupted")
   567  			continue
   568  		} else if err != nil {
   569  			t.Fatalf("Select: %v", err)
   570  		}
   571  		if n != 0 {
   572  			t.Fatalf("Select: got %v ready file descriptors, expected 0", n)
   573  		}
   574  		break
   575  	}
   576  
   577  	dur := 250 * time.Millisecond
   578  	var took time.Duration
   579  	for {
   580  		// On some platforms (e.g. Linux), the passed-in timeval is
   581  		// updated by select(2). Make sure to reset to the full duration
   582  		// in case of an EINTR.
   583  		tv := unix.NsecToTimeval(int64(dur))
   584  		start := time.Now()
   585  		n, err := unix.Select(0, nil, nil, nil, &tv)
   586  		took = time.Since(start)
   587  		if err == unix.EINTR {
   588  			t.Logf("Select interrupted after %v", took)
   589  			continue
   590  		} else if err != nil {
   591  			t.Fatalf("Select: %v", err)
   592  		}
   593  		if n != 0 {
   594  			t.Fatalf("Select: got %v ready file descriptors, expected 0", n)
   595  		}
   596  		break
   597  	}
   598  
   599  	// On some platforms (e.g. NetBSD) the actual timeout might be arbitrarily
   600  	// less than requested. However, Linux in particular promises to only return
   601  	// early if a file descriptor becomes ready (not applicable here), or the call
   602  	// is interrupted by a signal handler (explicitly retried in the loop above),
   603  	// or the timeout expires.
   604  	if took < dur {
   605  		if runtime.GOOS == "linux" {
   606  			t.Errorf("Select: slept for %v, expected %v", took, dur)
   607  		} else {
   608  			t.Logf("Select: slept for %v, requested %v", took, dur)
   609  		}
   610  	}
   611  
   612  	rr, ww, err := os.Pipe()
   613  	if err != nil {
   614  		t.Fatal(err)
   615  	}
   616  	defer rr.Close()
   617  	defer ww.Close()
   618  
   619  	if _, err := ww.Write([]byte("HELLO GOPHER")); err != nil {
   620  		t.Fatal(err)
   621  	}
   622  
   623  	rFdSet := &unix.FdSet{}
   624  	fd := int(rr.Fd())
   625  	rFdSet.Set(fd)
   626  
   627  	for {
   628  		n, err := unix.Select(fd+1, rFdSet, nil, nil, nil)
   629  		if err == unix.EINTR {
   630  			t.Log("Select interrupted")
   631  			continue
   632  		} else if err != nil {
   633  			t.Fatalf("Select: %v", err)
   634  		}
   635  		if n != 1 {
   636  			t.Fatalf("Select: got %v ready file descriptors, expected 1", n)
   637  		}
   638  		break
   639  	}
   640  }
   641  
   642  func TestGetwd(t *testing.T) {
   643  	fd, err := os.Open(".")
   644  	if err != nil {
   645  		t.Fatalf("Open .: %s", err)
   646  	}
   647  	defer fd.Close()
   648  	// Directory list for test. Do not worry if any are symlinks or do not
   649  	// exist on some common unix desktop environments. That will be checked.
   650  	dirs := []string{"/", "/usr/bin", "/etc", "/var", "/opt"}
   651  	switch runtime.GOOS {
   652  	case "android":
   653  		dirs = []string{"/", "/system/bin"}
   654  	case "ios":
   655  		dirs = []string{t.TempDir(), t.TempDir()}
   656  	}
   657  	oldwd := os.Getenv("PWD")
   658  	for _, d := range dirs {
   659  		// Check whether d exists, is a dir and that d's path does not contain a symlink
   660  		fi, err := os.Stat(d)
   661  		if err != nil || !fi.IsDir() {
   662  			t.Logf("Test dir %s stat error (%v) or not a directory, skipping", d, err)
   663  			continue
   664  		}
   665  		check, err := filepath.EvalSymlinks(d)
   666  		if err != nil || check != d {
   667  			t.Logf("Test dir %s (%s) is symlink or other error (%v), skipping", d, check, err)
   668  			continue
   669  		}
   670  		err = os.Chdir(d)
   671  		if err != nil {
   672  			t.Fatalf("Chdir: %v", err)
   673  		}
   674  		pwd, err := unix.Getwd()
   675  		if err != nil {
   676  			t.Fatalf("Getwd in %s: %s", d, err)
   677  		}
   678  		os.Setenv("PWD", oldwd)
   679  		err = fd.Chdir()
   680  		if err != nil {
   681  			// We changed the current directory and cannot go back.
   682  			// Don't let the tests continue; they'll scribble
   683  			// all over some other directory.
   684  			fmt.Fprintf(os.Stderr, "fchdir back to dot failed: %s\n", err)
   685  			os.Exit(1)
   686  		}
   687  		if pwd != d {
   688  			t.Fatalf("Getwd returned %q want %q", pwd, d)
   689  		}
   690  	}
   691  }
   692  
   693  func compareStat_t(t *testing.T, otherStat string, st1, st2 *unix.Stat_t) {
   694  	if st2.Dev != st1.Dev {
   695  		t.Errorf("%s/Fstatat: got dev %v, expected %v", otherStat, st2.Dev, st1.Dev)
   696  	}
   697  	if st2.Ino != st1.Ino {
   698  		t.Errorf("%s/Fstatat: got ino %v, expected %v", otherStat, st2.Ino, st1.Ino)
   699  	}
   700  	if st2.Mode != st1.Mode {
   701  		t.Errorf("%s/Fstatat: got mode %v, expected %v", otherStat, st2.Mode, st1.Mode)
   702  	}
   703  	if st2.Uid != st1.Uid {
   704  		t.Errorf("%s/Fstatat: got uid %v, expected %v", otherStat, st2.Uid, st1.Uid)
   705  	}
   706  	if st2.Gid != st1.Gid {
   707  		t.Errorf("%s/Fstatat: got gid %v, expected %v", otherStat, st2.Gid, st1.Gid)
   708  	}
   709  	if st2.Size != st1.Size {
   710  		t.Errorf("%s/Fstatat: got size %v, expected %v", otherStat, st2.Size, st1.Size)
   711  	}
   712  }
   713  
   714  func TestFstatat(t *testing.T) {
   715  	chtmpdir(t)
   716  
   717  	touch(t, "file1")
   718  
   719  	var st1 unix.Stat_t
   720  	err := unix.Stat("file1", &st1)
   721  	if err != nil {
   722  		t.Fatalf("Stat: %v", err)
   723  	}
   724  
   725  	var st2 unix.Stat_t
   726  	err = unix.Fstatat(unix.AT_FDCWD, "file1", &st2, 0)
   727  	if err != nil {
   728  		t.Fatalf("Fstatat: %v", err)
   729  	}
   730  
   731  	compareStat_t(t, "Stat", &st1, &st2)
   732  
   733  	err = os.Symlink("file1", "symlink1")
   734  	if err != nil {
   735  		t.Fatal(err)
   736  	}
   737  
   738  	err = unix.Lstat("symlink1", &st1)
   739  	if err != nil {
   740  		t.Fatalf("Lstat: %v", err)
   741  	}
   742  
   743  	err = unix.Fstatat(unix.AT_FDCWD, "symlink1", &st2, unix.AT_SYMLINK_NOFOLLOW)
   744  	if err != nil {
   745  		t.Fatalf("Fstatat: %v", err)
   746  	}
   747  
   748  	compareStat_t(t, "Lstat", &st1, &st2)
   749  }
   750  
   751  func TestFchmodat(t *testing.T) {
   752  	chtmpdir(t)
   753  
   754  	touch(t, "file1")
   755  	err := os.Symlink("file1", "symlink1")
   756  	if err != nil {
   757  		t.Fatal(err)
   758  	}
   759  
   760  	mode := os.FileMode(0444)
   761  	err = unix.Fchmodat(unix.AT_FDCWD, "symlink1", uint32(mode), 0)
   762  	if err != nil {
   763  		t.Fatalf("Fchmodat: unexpected error: %v", err)
   764  	}
   765  
   766  	fi, err := os.Stat("file1")
   767  	if err != nil {
   768  		t.Fatal(err)
   769  	}
   770  
   771  	if fi.Mode() != mode {
   772  		t.Errorf("Fchmodat: failed to change file mode: expected %v, got %v", mode, fi.Mode())
   773  	}
   774  
   775  	mode = os.FileMode(0644)
   776  	didChmodSymlink := true
   777  	err = unix.Fchmodat(unix.AT_FDCWD, "symlink1", uint32(mode), unix.AT_SYMLINK_NOFOLLOW)
   778  	if err != nil {
   779  		if (runtime.GOOS == "android" || runtime.GOOS == "linux" ||
   780  			runtime.GOOS == "solaris" || runtime.GOOS == "illumos") && err == unix.EOPNOTSUPP {
   781  			// Linux and Illumos don't support flags != 0
   782  			didChmodSymlink = false
   783  		} else {
   784  			t.Fatalf("Fchmodat: unexpected error: %v", err)
   785  		}
   786  	}
   787  
   788  	if !didChmodSymlink {
   789  		// Didn't change mode of the symlink. On Linux, the permissions
   790  		// of a symbolic link are always 0777 according to symlink(7)
   791  		mode = os.FileMode(0777)
   792  	}
   793  
   794  	var st unix.Stat_t
   795  	err = unix.Lstat("symlink1", &st)
   796  	if err != nil {
   797  		t.Fatal(err)
   798  	}
   799  
   800  	got := os.FileMode(st.Mode & 0777)
   801  	if got != mode {
   802  		t.Errorf("Fchmodat: failed to change symlink mode: expected %v, got %v", mode, got)
   803  	}
   804  }
   805  
   806  func TestMkdev(t *testing.T) {
   807  	major := uint32(42)
   808  	minor := uint32(7)
   809  	dev := unix.Mkdev(major, minor)
   810  
   811  	if unix.Major(dev) != major {
   812  		t.Errorf("Major(%#x) == %d, want %d", dev, unix.Major(dev), major)
   813  	}
   814  	if unix.Minor(dev) != minor {
   815  		t.Errorf("Minor(%#x) == %d, want %d", dev, unix.Minor(dev), minor)
   816  	}
   817  }
   818  
   819  func TestPipe(t *testing.T) {
   820  	const s = "hello"
   821  	var pipes [2]int
   822  	err := unix.Pipe(pipes[:])
   823  	if err != nil {
   824  		t.Fatalf("pipe: %v", err)
   825  	}
   826  	r := pipes[0]
   827  	w := pipes[1]
   828  	go func() {
   829  		n, err := unix.Write(w, []byte(s))
   830  		if err != nil {
   831  			t.Errorf("bad write: %v", err)
   832  			return
   833  		}
   834  		if n != len(s) {
   835  			t.Errorf("bad write count: %d", n)
   836  			return
   837  		}
   838  		err = unix.Close(w)
   839  		if err != nil {
   840  			t.Errorf("bad close: %v", err)
   841  			return
   842  		}
   843  	}()
   844  	var buf [10 + len(s)]byte
   845  	n, err := unix.Read(r, buf[:])
   846  	if err != nil {
   847  		t.Fatalf("bad read: %v", err)
   848  	}
   849  	if n != len(s) {
   850  		t.Fatalf("bad read count: %d", n)
   851  	}
   852  	if string(buf[:n]) != s {
   853  		t.Fatalf("bad contents: %s", string(buf[:n]))
   854  	}
   855  	err = unix.Close(r)
   856  	if err != nil {
   857  		t.Fatalf("bad close: %v", err)
   858  	}
   859  }
   860  
   861  func TestRenameat(t *testing.T) {
   862  	chtmpdir(t)
   863  
   864  	from, to := "renamefrom", "renameto"
   865  
   866  	touch(t, from)
   867  
   868  	err := unix.Renameat(unix.AT_FDCWD, from, unix.AT_FDCWD, to)
   869  	if err != nil {
   870  		t.Fatalf("Renameat: unexpected error: %v", err)
   871  	}
   872  
   873  	_, err = os.Stat(to)
   874  	if err != nil {
   875  		t.Error(err)
   876  	}
   877  
   878  	_, err = os.Stat(from)
   879  	if err == nil {
   880  		t.Errorf("Renameat: stat of renamed file %q unexpectedly succeeded", from)
   881  	}
   882  }
   883  
   884  func TestUtimesNanoAt(t *testing.T) {
   885  	chtmpdir(t)
   886  
   887  	symlink := "symlink1"
   888  	os.Remove(symlink)
   889  	err := os.Symlink("nonexisting", symlink)
   890  	if err != nil {
   891  		t.Fatal(err)
   892  	}
   893  
   894  	// Some filesystems only support microsecond resolution. Account for
   895  	// that in Nsec.
   896  	ts := []unix.Timespec{
   897  		{Sec: 1111, Nsec: 2000},
   898  		{Sec: 3333, Nsec: 4000},
   899  	}
   900  	err = unix.UtimesNanoAt(unix.AT_FDCWD, symlink, ts, unix.AT_SYMLINK_NOFOLLOW)
   901  	if err != nil {
   902  		t.Fatalf("UtimesNanoAt: %v", err)
   903  	}
   904  
   905  	var st unix.Stat_t
   906  	err = unix.Lstat(symlink, &st)
   907  	if err != nil {
   908  		t.Fatalf("Lstat: %v", err)
   909  	}
   910  
   911  	// Only check Mtim, Atim might not be supported by the underlying filesystem
   912  	expected := ts[1]
   913  	if st.Mtim.Nsec == 0 {
   914  		// Some filesystems only support 1-second time stamp resolution
   915  		// and will always set Nsec to 0.
   916  		expected.Nsec = 0
   917  	}
   918  	if st.Mtim != expected {
   919  		t.Errorf("UtimesNanoAt: wrong mtime: got %v, expected %v", st.Mtim, expected)
   920  	}
   921  }
   922  
   923  func TestSend(t *testing.T) {
   924  	ec := make(chan error, 2)
   925  	ts := []byte("HELLO GOPHER")
   926  
   927  	fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_STREAM, 0)
   928  	if err != nil {
   929  		t.Fatalf("Socketpair: %v", err)
   930  	}
   931  	defer unix.Close(fds[0])
   932  	defer unix.Close(fds[1])
   933  
   934  	go func() {
   935  		data := make([]byte, len(ts))
   936  
   937  		_, _, err := unix.Recvfrom(fds[1], data, 0)
   938  		if err != nil {
   939  			ec <- err
   940  		}
   941  		if !bytes.Equal(ts, data) {
   942  			ec <- fmt.Errorf("data sent != data received. Received %q", data)
   943  		}
   944  		ec <- nil
   945  	}()
   946  	err = unix.Send(fds[0], ts, 0)
   947  	if err != nil {
   948  		ec <- err
   949  	}
   950  
   951  	select {
   952  	case err = <-ec:
   953  		if err != nil {
   954  			t.Fatalf("Send: %v", err)
   955  		}
   956  	case <-time.After(2 * time.Second):
   957  		t.Fatal("Send: nothing received after 2 seconds")
   958  	}
   959  }
   960  
   961  func TestSendmsgBuffers(t *testing.T) {
   962  	fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_STREAM, 0)
   963  	if err != nil {
   964  		t.Fatal(err)
   965  	}
   966  	defer unix.Close(fds[0])
   967  	defer unix.Close(fds[1])
   968  
   969  	var wg sync.WaitGroup
   970  	wg.Add(1)
   971  	go func() {
   972  		defer wg.Done()
   973  		bufs := [][]byte{
   974  			make([]byte, 5),
   975  			nil,
   976  			make([]byte, 5),
   977  		}
   978  		n, oobn, recvflags, _, err := unix.RecvmsgBuffers(fds[1], bufs, nil, 0)
   979  		if err != nil {
   980  			t.Error(err)
   981  			return
   982  		}
   983  		if n != 10 {
   984  			t.Errorf("got %d bytes, want 10", n)
   985  		}
   986  		if oobn != 0 {
   987  			t.Errorf("got %d OOB bytes, want 0", oobn)
   988  		}
   989  		if recvflags != 0 {
   990  			t.Errorf("got flags %#x, want %#x", recvflags, 0)
   991  		}
   992  		want := [][]byte{
   993  			[]byte("01234"),
   994  			nil,
   995  			[]byte("56789"),
   996  		}
   997  		if !reflect.DeepEqual(bufs, want) {
   998  			t.Errorf("got data %q, want %q", bufs, want)
   999  		}
  1000  	}()
  1001  
  1002  	defer wg.Wait()
  1003  
  1004  	bufs := [][]byte{
  1005  		[]byte("012"),
  1006  		[]byte("34"),
  1007  		nil,
  1008  		[]byte("5678"),
  1009  		[]byte("9"),
  1010  	}
  1011  	n, err := unix.SendmsgBuffers(fds[0], bufs, nil, nil, 0)
  1012  	if err != nil {
  1013  		t.Fatal(err)
  1014  	}
  1015  	if n != 10 {
  1016  		t.Errorf("sent %d bytes, want 10", n)
  1017  	}
  1018  }
  1019  
  1020  // Issue 56384.
  1021  func TestRecvmsgControl(t *testing.T) {
  1022  	switch runtime.GOOS {
  1023  	case "solaris", "illumos":
  1024  		// Test fails on Solaris, saying
  1025  		// "got 0 control messages, want 1".
  1026  		// Not sure why; Solaris recvmsg man page says
  1027  		// "For processes on the same host, recvmsg() can be
  1028  		// used to receive a file descriptor from another
  1029  		// process, but it cannot receive ancillary data."
  1030  		t.Skipf("skipping on %s", runtime.GOOS)
  1031  	}
  1032  
  1033  	fds, err := unix.Socketpair(unix.AF_UNIX, unix.SOCK_STREAM, 0)
  1034  	if err != nil {
  1035  		t.Fatal(err)
  1036  	}
  1037  	defer unix.Close(fds[0])
  1038  	defer unix.Close(fds[1])
  1039  
  1040  	const payload = "hello"
  1041  
  1042  	// Start a goroutine that sends a control message followed by
  1043  	// a payload on fds[1].
  1044  	go func() {
  1045  		f, err := os.Create(filepath.Join(t.TempDir(), "file"))
  1046  		if err != nil {
  1047  			t.Error(err)
  1048  			return
  1049  		}
  1050  		defer f.Close()
  1051  
  1052  		rc, err := f.SyscallConn()
  1053  		if err != nil {
  1054  			t.Error(err)
  1055  			return
  1056  		}
  1057  		var rights []byte
  1058  		err = rc.Control(func(fd uintptr) {
  1059  			rights = unix.UnixRights(int(fd))
  1060  		})
  1061  		if err != nil {
  1062  			t.Error(err)
  1063  			return
  1064  		}
  1065  
  1066  		_, err = unix.SendmsgN(fds[1], nil, rights, nil, 0)
  1067  		if err != nil {
  1068  			t.Error(err)
  1069  		}
  1070  		if _, err := unix.Write(fds[1], []byte(payload)); err != nil {
  1071  			t.Error(err)
  1072  		}
  1073  	}()
  1074  
  1075  	// Read the control message sent by the goroutine.  The
  1076  	// goroutine writes to fds[1], we read from fds[0].
  1077  
  1078  	cbuf := make([]byte, unix.CmsgSpace(4))
  1079  	_, cn, _, _, err := unix.Recvmsg(fds[0], nil, cbuf, 0)
  1080  	if err != nil {
  1081  		t.Fatal(err)
  1082  	}
  1083  	cbuf = cbuf[:cn]
  1084  
  1085  	// Read the payload sent by the goroutine.
  1086  
  1087  	buf := make([]byte, len(payload))
  1088  	n, err := unix.Read(fds[0], buf)
  1089  	if err != nil {
  1090  		t.Fatal(err)
  1091  	}
  1092  	buf = buf[:n]
  1093  	if payload != string(buf) {
  1094  		t.Errorf("read payload %q, want %q", buf, payload)
  1095  	}
  1096  
  1097  	// Check the control message.
  1098  
  1099  	cmsgs, err := unix.ParseSocketControlMessage(cbuf)
  1100  	if err != nil {
  1101  		t.Fatal(err)
  1102  	}
  1103  	if len(cmsgs) != 1 {
  1104  		t.Fatalf("got %d control messages, want 1", len(cmsgs))
  1105  	}
  1106  	cfds, err := unix.ParseUnixRights(&cmsgs[0])
  1107  	if err != nil {
  1108  		t.Fatal(err)
  1109  	}
  1110  	if len(cfds) != 1 {
  1111  		t.Fatalf("got %d fds, want 1", len(cfds))
  1112  	}
  1113  	defer unix.Close(cfds[0])
  1114  }
  1115  
  1116  // mktmpfifo creates a temporary FIFO and sets up a cleanup function.
  1117  func mktmpfifo(t *testing.T) *os.File {
  1118  	t.Helper()
  1119  	err := unix.Mkfifo("fifo", 0666)
  1120  	if err != nil {
  1121  		t.Fatalf("mktmpfifo: failed to create FIFO: %v", err)
  1122  	}
  1123  
  1124  	f, err := os.OpenFile("fifo", os.O_RDWR, 0666)
  1125  	if err != nil {
  1126  		os.Remove("fifo")
  1127  		t.Fatal(err)
  1128  	}
  1129  	t.Cleanup(func() {
  1130  		f.Close()
  1131  		os.Remove("fifo")
  1132  	})
  1133  
  1134  	return f
  1135  }
  1136  
  1137  // utilities taken from os/os_test.go
  1138  
  1139  func touch(t *testing.T, name string) {
  1140  	t.Helper()
  1141  	f, err := os.Create(name)
  1142  	if err != nil {
  1143  		t.Fatal(err)
  1144  	}
  1145  	if err := f.Close(); err != nil {
  1146  		t.Fatal(err)
  1147  	}
  1148  }
  1149  
  1150  // chtmpdir changes the working directory to a new temporary directory and
  1151  // sets up a cleanup function. Used when PWD is read-only.
  1152  func chtmpdir(t *testing.T) {
  1153  	t.Helper()
  1154  	oldwd, err := os.Getwd()
  1155  	if err != nil {
  1156  		t.Fatal(err)
  1157  	}
  1158  	if err := os.Chdir(t.TempDir()); err != nil {
  1159  		t.Fatal(err)
  1160  	}
  1161  	t.Cleanup(func() {
  1162  		if err := os.Chdir(oldwd); err != nil {
  1163  			t.Fatal(err)
  1164  		}
  1165  	})
  1166  }
  1167  

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