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

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