syscall_unix_test.go

     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 unix
     6  
     7  package syscall_test
     8  
     9  import (
    10  	"flag"
    11  	"fmt"
    12  	"internal/testenv"
    13  	"io"
    14  	"net"
    15  	"os"
    16  	"os/exec"
    17  	"path/filepath"
    18  	"runtime"
    19  	"strconv"
    20  	"syscall"
    21  	"testing"
    22  	"time"
    23  )
    24  
    25  // Tests that below functions, structures and constants are consistent
    26  // on all Unix-like systems.
    27  func _() {
    28  	// program scheduling priority functions and constants
    29  	var (
    30  		_ func(int, int, int) error   = syscall.Setpriority
    31  		_ func(int, int) (int, error) = syscall.Getpriority
    32  	)
    33  	const (
    34  		_ int = syscall.PRIO_USER
    35  		_ int = syscall.PRIO_PROCESS
    36  		_ int = syscall.PRIO_PGRP
    37  	)
    38  
    39  	// termios constants
    40  	const (
    41  		_ int = syscall.TCIFLUSH
    42  		_ int = syscall.TCIOFLUSH
    43  		_ int = syscall.TCOFLUSH
    44  	)
    45  
    46  	// fcntl file locking structure and constants
    47  	var (
    48  		_ = syscall.Flock_t{
    49  			Type:   int16(0),
    50  			Whence: int16(0),
    51  			Start:  int64(0),
    52  			Len:    int64(0),
    53  			Pid:    int32(0),
    54  		}
    55  	)
    56  	const (
    57  		_ = syscall.F_GETLK
    58  		_ = syscall.F_SETLK
    59  		_ = syscall.F_SETLKW
    60  	)
    61  }
    62  
    63  // TestFcntlFlock tests whether the file locking structure matches
    64  // the calling convention of each kernel.
    65  // On some Linux systems, glibc uses another set of values for the
    66  // commands and translates them to the correct value that the kernel
    67  // expects just before the actual fcntl syscall. As Go uses raw
    68  // syscalls directly, it must use the real value, not the glibc value.
    69  // Thus this test also verifies that the Flock_t structure can be
    70  // roundtripped with F_SETLK and F_GETLK.
    71  func TestFcntlFlock(t *testing.T) {
    72  	if runtime.GOOS == "ios" {
    73  		t.Skip("skipping; no child processes allowed on iOS")
    74  	}
    75  	flock := syscall.Flock_t{
    76  		Type:  syscall.F_WRLCK,
    77  		Start: 31415, Len: 271828, Whence: 1,
    78  	}
    79  	if os.Getenv("GO_WANT_HELPER_PROCESS") == "" {
    80  		// parent
    81  		tempDir := t.TempDir()
    82  		name := filepath.Join(tempDir, "TestFcntlFlock")
    83  		fd, err := syscall.Open(name, syscall.O_CREAT|syscall.O_RDWR|syscall.O_CLOEXEC, 0)
    84  		if err != nil {
    85  			t.Fatalf("Open failed: %v", err)
    86  		}
    87  		// f takes ownership of fd, and will close it.
    88  		//
    89  		// N.B. This defer is also necessary to keep f alive
    90  		// while we use its fd, preventing its finalizer from
    91  		// executing.
    92  		f := os.NewFile(uintptr(fd), name)
    93  		defer f.Close()
    94  
    95  		if err := syscall.Ftruncate(int(f.Fd()), 1<<20); err != nil {
    96  			t.Fatalf("Ftruncate(1<<20) failed: %v", err)
    97  		}
    98  		if err := syscall.FcntlFlock(f.Fd(), syscall.F_SETLK, &flock); err != nil {
    99  			t.Fatalf("FcntlFlock(F_SETLK) failed: %v", err)
   100  		}
   101  
   102  		cmd := exec.Command(os.Args[0], "-test.run=^TestFcntlFlock$")
   103  		cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
   104  		cmd.ExtraFiles = []*os.File{f}
   105  		out, err := cmd.CombinedOutput()
   106  		if len(out) > 0 || err != nil {
   107  			t.Fatalf("child process: %q, %v", out, err)
   108  		}
   109  	} else {
   110  		// child
   111  		got := flock
   112  		// make sure the child lock is conflicting with the parent lock
   113  		got.Start--
   114  		got.Len++
   115  		if err := syscall.FcntlFlock(3, syscall.F_GETLK, &got); err != nil {
   116  			t.Fatalf("FcntlFlock(F_GETLK) failed: %v", err)
   117  		}
   118  		flock.Pid = int32(syscall.Getppid())
   119  		// Linux kernel always set Whence to 0
   120  		flock.Whence = 0
   121  		if got.Type == flock.Type && got.Start == flock.Start && got.Len == flock.Len && got.Pid == flock.Pid && got.Whence == flock.Whence {
   122  			os.Exit(0)
   123  		}
   124  		t.Fatalf("FcntlFlock got %v, want %v", got, flock)
   125  	}
   126  }
   127  
   128  // TestPassFD tests passing a file descriptor over a Unix socket.
   129  //
   130  // This test involved both a parent and child process. The parent
   131  // process is invoked as a normal test, with "go test", which then
   132  // runs the child process by running the current test binary with args
   133  // "-test.run=^TestPassFD$" and an environment variable used to signal
   134  // that the test should become the child process instead.
   135  func TestPassFD(t *testing.T) {
   136  	testenv.MustHaveExec(t)
   137  
   138  	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
   139  		passFDChild()
   140  		return
   141  	}
   142  
   143  	if runtime.GOOS == "aix" {
   144  		// Unix network isn't properly working on AIX 7.2 with Technical Level < 2
   145  		out, err := exec.Command("oslevel", "-s").Output()
   146  		if err != nil {
   147  			t.Skipf("skipping on AIX because oslevel -s failed: %v", err)
   148  		}
   149  		if len(out) < len("7200-XX-ZZ-YYMM") { // AIX 7.2, Tech Level XX, Service Pack ZZ, date YYMM
   150  			t.Skip("skipping on AIX because oslevel -s hasn't the right length")
   151  		}
   152  		aixVer := string(out[:4])
   153  		tl, err := strconv.Atoi(string(out[5:7]))
   154  		if err != nil {
   155  			t.Skipf("skipping on AIX because oslevel -s output cannot be parsed: %v", err)
   156  		}
   157  		if aixVer < "7200" || (aixVer == "7200" && tl < 2) {
   158  			t.Skip("skipped on AIX versions previous to 7.2 TL 2")
   159  		}
   160  
   161  	}
   162  
   163  	tempDir := t.TempDir()
   164  
   165  	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
   166  	if err != nil {
   167  		t.Fatalf("Socketpair: %v", err)
   168  	}
   169  	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
   170  	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
   171  	defer writeFile.Close()
   172  	defer readFile.Close()
   173  
   174  	cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
   175  	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
   176  	cmd.ExtraFiles = []*os.File{writeFile}
   177  
   178  	out, err := cmd.CombinedOutput()
   179  	if len(out) > 0 || err != nil {
   180  		t.Fatalf("child process: %q, %v", out, err)
   181  	}
   182  
   183  	c, err := net.FileConn(readFile)
   184  	if err != nil {
   185  		t.Fatalf("FileConn: %v", err)
   186  	}
   187  	defer c.Close()
   188  
   189  	uc, ok := c.(*net.UnixConn)
   190  	if !ok {
   191  		t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
   192  	}
   193  
   194  	buf := make([]byte, 32) // expect 1 byte
   195  	oob := make([]byte, 32) // expect 24 bytes
   196  	closeUnix := time.AfterFunc(5*time.Second, func() {
   197  		t.Logf("timeout reading from unix socket")
   198  		uc.Close()
   199  	})
   200  	_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
   201  	if err != nil {
   202  		t.Fatalf("ReadMsgUnix: %v", err)
   203  	}
   204  	closeUnix.Stop()
   205  
   206  	scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
   207  	if err != nil {
   208  		t.Fatalf("ParseSocketControlMessage: %v", err)
   209  	}
   210  	if len(scms) != 1 {
   211  		t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
   212  	}
   213  	scm := scms[0]
   214  	gotFds, err := syscall.ParseUnixRights(&scm)
   215  	if err != nil {
   216  		t.Fatalf("syscall.ParseUnixRights: %v", err)
   217  	}
   218  	if len(gotFds) != 1 {
   219  		t.Fatalf("wanted 1 fd; got %#v", gotFds)
   220  	}
   221  
   222  	f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
   223  	defer f.Close()
   224  
   225  	got, err := io.ReadAll(f)
   226  	want := "Hello from child process!\n"
   227  	if string(got) != want {
   228  		t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
   229  	}
   230  }
   231  
   232  // passFDChild is the child process used by TestPassFD.
   233  func passFDChild() {
   234  	defer os.Exit(0)
   235  
   236  	// Look for our fd. It should be fd 3, but we work around an fd leak
   237  	// bug here (https://golang.org/issue/2603) to let it be elsewhere.
   238  	var uc *net.UnixConn
   239  	for fd := uintptr(3); fd <= 10; fd++ {
   240  		f := os.NewFile(fd, "unix-conn")
   241  		var ok bool
   242  		netc, _ := net.FileConn(f)
   243  		uc, ok = netc.(*net.UnixConn)
   244  		if ok {
   245  			break
   246  		}
   247  	}
   248  	if uc == nil {
   249  		fmt.Println("failed to find unix fd")
   250  		return
   251  	}
   252  
   253  	// Make a file f to send to our parent process on uc.
   254  	// We make it in tempDir, which our parent will clean up.
   255  	flag.Parse()
   256  	tempDir := flag.Arg(0)
   257  	f, err := os.CreateTemp(tempDir, "")
   258  	if err != nil {
   259  		fmt.Printf("TempFile: %v", err)
   260  		return
   261  	}
   262  	// N.B. This defer is also necessary to keep f alive
   263  	// while we use its fd, preventing its finalizer from
   264  	// executing.
   265  	defer f.Close()
   266  
   267  	f.Write([]byte("Hello from child process!\n"))
   268  	f.Seek(0, io.SeekStart)
   269  
   270  	rights := syscall.UnixRights(int(f.Fd()))
   271  	dummyByte := []byte("x")
   272  	n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
   273  	if err != nil {
   274  		fmt.Printf("WriteMsgUnix: %v", err)
   275  		return
   276  	}
   277  	if n != 1 || oobn != len(rights) {
   278  		fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
   279  		return
   280  	}
   281  }
   282  
   283  // TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage,
   284  // and ParseUnixRights are able to successfully round-trip lists of file descriptors.
   285  func TestUnixRightsRoundtrip(t *testing.T) {
   286  	testCases := [...][][]int{
   287  		{{42}},
   288  		{{1, 2}},
   289  		{{3, 4, 5}},
   290  		{{}},
   291  		{{1, 2}, {3, 4, 5}, {}, {7}},
   292  	}
   293  	for _, testCase := range testCases {
   294  		b := []byte{}
   295  		var n int
   296  		for _, fds := range testCase {
   297  			// Last assignment to n wins
   298  			n = len(b) + syscall.CmsgLen(4*len(fds))
   299  			b = append(b, syscall.UnixRights(fds...)...)
   300  		}
   301  		// Truncate b
   302  		b = b[:n]
   303  
   304  		scms, err := syscall.ParseSocketControlMessage(b)
   305  		if err != nil {
   306  			t.Fatalf("ParseSocketControlMessage: %v", err)
   307  		}
   308  		if len(scms) != len(testCase) {
   309  			t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
   310  		}
   311  		for i, scm := range scms {
   312  			gotFds, err := syscall.ParseUnixRights(&scm)
   313  			if err != nil {
   314  				t.Fatalf("ParseUnixRights: %v", err)
   315  			}
   316  			wantFds := testCase[i]
   317  			if len(gotFds) != len(wantFds) {
   318  				t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
   319  			}
   320  			for j, fd := range gotFds {
   321  				if fd != wantFds[j] {
   322  					t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
   323  				}
   324  			}
   325  		}
   326  	}
   327  }
   328  
   329  func TestSeekFailure(t *testing.T) {
   330  	_, err := syscall.Seek(-1, 0, io.SeekStart)
   331  	if err == nil {
   332  		t.Fatalf("Seek(-1, 0, 0) did not fail")
   333  	}
   334  	str := err.Error() // used to crash on Linux
   335  	t.Logf("Seek: %v", str)
   336  	if str == "" {
   337  		t.Fatalf("Seek(-1, 0, 0) return error with empty message")
   338  	}
   339  }
   340  
   341  func TestSetsockoptString(t *testing.T) {
   342  	// should not panic on empty string, see issue #31277
   343  	err := syscall.SetsockoptString(-1, 0, 0, "")
   344  	if err == nil {
   345  		t.Fatalf("SetsockoptString: did not fail")
   346  	}
   347  }
   348  
   349  func TestENFILETemporary(t *testing.T) {
   350  	if !syscall.ENFILE.Temporary() {
   351  		t.Error("ENFILE is not treated as a temporary error")
   352  	}
   353  }
   354
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