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Source file src/syscall/syscall_unix_test.go

Documentation: syscall

     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  // +build darwin dragonfly freebsd linux netbsd openbsd solaris
     6  
     7  package syscall_test
     8  
     9  import (
    10  	"flag"
    11  	"fmt"
    12  	"internal/testenv"
    13  	"io"
    14  	"io/ioutil"
    15  	"net"
    16  	"os"
    17  	"os/exec"
    18  	"path/filepath"
    19  	"runtime"
    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 == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
    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, err := ioutil.TempDir("", "TestFcntlFlock")
    82  		if err != nil {
    83  			t.Fatalf("Failed to create temp dir: %v", err)
    84  		}
    85  		name := filepath.Join(tempDir, "TestFcntlFlock")
    86  		fd, err := syscall.Open(name, syscall.O_CREAT|syscall.O_RDWR|syscall.O_CLOEXEC, 0)
    87  		if err != nil {
    88  			t.Fatalf("Open failed: %v", err)
    89  		}
    90  		defer os.RemoveAll(tempDir)
    91  		defer syscall.Close(fd)
    92  		if err := syscall.Ftruncate(fd, 1<<20); err != nil {
    93  			t.Fatalf("Ftruncate(1<<20) failed: %v", err)
    94  		}
    95  		if err := syscall.FcntlFlock(uintptr(fd), syscall.F_SETLK, &flock); err != nil {
    96  			t.Fatalf("FcntlFlock(F_SETLK) failed: %v", err)
    97  		}
    98  		cmd := exec.Command(os.Args[0], "-test.run=^TestFcntlFlock$")
    99  		cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
   100  		cmd.ExtraFiles = []*os.File{os.NewFile(uintptr(fd), name)}
   101  		out, err := cmd.CombinedOutput()
   102  		if len(out) > 0 || err != nil {
   103  			t.Fatalf("child process: %q, %v", out, err)
   104  		}
   105  	} else {
   106  		// child
   107  		got := flock
   108  		// make sure the child lock is conflicting with the parent lock
   109  		got.Start--
   110  		got.Len++
   111  		if err := syscall.FcntlFlock(3, syscall.F_GETLK, &got); err != nil {
   112  			t.Fatalf("FcntlFlock(F_GETLK) failed: %v", err)
   113  		}
   114  		flock.Pid = int32(syscall.Getppid())
   115  		// Linux kernel always set Whence to 0
   116  		flock.Whence = 0
   117  		if got.Type == flock.Type && got.Start == flock.Start && got.Len == flock.Len && got.Pid == flock.Pid && got.Whence == flock.Whence {
   118  			os.Exit(0)
   119  		}
   120  		t.Fatalf("FcntlFlock got %v, want %v", got, flock)
   121  	}
   122  }
   123  
   124  // TestPassFD tests passing a file descriptor over a Unix socket.
   125  //
   126  // This test involved both a parent and child process. The parent
   127  // process is invoked as a normal test, with "go test", which then
   128  // runs the child process by running the current test binary with args
   129  // "-test.run=^TestPassFD$" and an environment variable used to signal
   130  // that the test should become the child process instead.
   131  func TestPassFD(t *testing.T) {
   132  	testenv.MustHaveExec(t)
   133  
   134  	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
   135  		passFDChild()
   136  		return
   137  	}
   138  
   139  	tempDir, err := ioutil.TempDir("", "TestPassFD")
   140  	if err != nil {
   141  		t.Fatal(err)
   142  	}
   143  	defer os.RemoveAll(tempDir)
   144  
   145  	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
   146  	if err != nil {
   147  		t.Fatalf("Socketpair: %v", err)
   148  	}
   149  	defer syscall.Close(fds[0])
   150  	defer syscall.Close(fds[1])
   151  	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
   152  	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
   153  	defer writeFile.Close()
   154  	defer readFile.Close()
   155  
   156  	cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
   157  	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
   158  	cmd.ExtraFiles = []*os.File{writeFile}
   159  
   160  	out, err := cmd.CombinedOutput()
   161  	if len(out) > 0 || err != nil {
   162  		t.Fatalf("child process: %q, %v", out, err)
   163  	}
   164  
   165  	c, err := net.FileConn(readFile)
   166  	if err != nil {
   167  		t.Fatalf("FileConn: %v", err)
   168  	}
   169  	defer c.Close()
   170  
   171  	uc, ok := c.(*net.UnixConn)
   172  	if !ok {
   173  		t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
   174  	}
   175  
   176  	buf := make([]byte, 32) // expect 1 byte
   177  	oob := make([]byte, 32) // expect 24 bytes
   178  	closeUnix := time.AfterFunc(5*time.Second, func() {
   179  		t.Logf("timeout reading from unix socket")
   180  		uc.Close()
   181  	})
   182  	_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
   183  	if err != nil {
   184  		t.Fatalf("ReadMsgUnix: %v", err)
   185  	}
   186  	closeUnix.Stop()
   187  
   188  	scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
   189  	if err != nil {
   190  		t.Fatalf("ParseSocketControlMessage: %v", err)
   191  	}
   192  	if len(scms) != 1 {
   193  		t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
   194  	}
   195  	scm := scms[0]
   196  	gotFds, err := syscall.ParseUnixRights(&scm)
   197  	if err != nil {
   198  		t.Fatalf("syscall.ParseUnixRights: %v", err)
   199  	}
   200  	if len(gotFds) != 1 {
   201  		t.Fatalf("wanted 1 fd; got %#v", gotFds)
   202  	}
   203  
   204  	f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
   205  	defer f.Close()
   206  
   207  	got, err := ioutil.ReadAll(f)
   208  	want := "Hello from child process!\n"
   209  	if string(got) != want {
   210  		t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
   211  	}
   212  }
   213  
   214  // passFDChild is the child process used by TestPassFD.
   215  func passFDChild() {
   216  	defer os.Exit(0)
   217  
   218  	// Look for our fd. It should be fd 3, but we work around an fd leak
   219  	// bug here (https://golang.org/issue/2603) to let it be elsewhere.
   220  	var uc *net.UnixConn
   221  	for fd := uintptr(3); fd <= 10; fd++ {
   222  		f := os.NewFile(fd, "unix-conn")
   223  		var ok bool
   224  		netc, _ := net.FileConn(f)
   225  		uc, ok = netc.(*net.UnixConn)
   226  		if ok {
   227  			break
   228  		}
   229  	}
   230  	if uc == nil {
   231  		fmt.Println("failed to find unix fd")
   232  		return
   233  	}
   234  
   235  	// Make a file f to send to our parent process on uc.
   236  	// We make it in tempDir, which our parent will clean up.
   237  	flag.Parse()
   238  	tempDir := flag.Arg(0)
   239  	f, err := ioutil.TempFile(tempDir, "")
   240  	if err != nil {
   241  		fmt.Printf("TempFile: %v", err)
   242  		return
   243  	}
   244  
   245  	f.Write([]byte("Hello from child process!\n"))
   246  	f.Seek(0, io.SeekStart)
   247  
   248  	rights := syscall.UnixRights(int(f.Fd()))
   249  	dummyByte := []byte("x")
   250  	n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
   251  	if err != nil {
   252  		fmt.Printf("WriteMsgUnix: %v", err)
   253  		return
   254  	}
   255  	if n != 1 || oobn != len(rights) {
   256  		fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
   257  		return
   258  	}
   259  }
   260  
   261  // TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage,
   262  // and ParseUnixRights are able to successfully round-trip lists of file descriptors.
   263  func TestUnixRightsRoundtrip(t *testing.T) {
   264  	testCases := [...][][]int{
   265  		{{42}},
   266  		{{1, 2}},
   267  		{{3, 4, 5}},
   268  		{{}},
   269  		{{1, 2}, {3, 4, 5}, {}, {7}},
   270  	}
   271  	for _, testCase := range testCases {
   272  		b := []byte{}
   273  		var n int
   274  		for _, fds := range testCase {
   275  			// Last assignment to n wins
   276  			n = len(b) + syscall.CmsgLen(4*len(fds))
   277  			b = append(b, syscall.UnixRights(fds...)...)
   278  		}
   279  		// Truncate b
   280  		b = b[:n]
   281  
   282  		scms, err := syscall.ParseSocketControlMessage(b)
   283  		if err != nil {
   284  			t.Fatalf("ParseSocketControlMessage: %v", err)
   285  		}
   286  		if len(scms) != len(testCase) {
   287  			t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
   288  		}
   289  		for i, scm := range scms {
   290  			gotFds, err := syscall.ParseUnixRights(&scm)
   291  			if err != nil {
   292  				t.Fatalf("ParseUnixRights: %v", err)
   293  			}
   294  			wantFds := testCase[i]
   295  			if len(gotFds) != len(wantFds) {
   296  				t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
   297  			}
   298  			for j, fd := range gotFds {
   299  				if fd != wantFds[j] {
   300  					t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
   301  				}
   302  			}
   303  		}
   304  	}
   305  }
   306  
   307  func TestRlimit(t *testing.T) {
   308  	var rlimit, zero syscall.Rlimit
   309  	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit)
   310  	if err != nil {
   311  		t.Fatalf("Getrlimit: save failed: %v", err)
   312  	}
   313  	if zero == rlimit {
   314  		t.Fatalf("Getrlimit: save failed: got zero value %#v", rlimit)
   315  	}
   316  	set := rlimit
   317  	set.Cur = set.Max - 1
   318  	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &set)
   319  	if err != nil {
   320  		t.Fatalf("Setrlimit: set failed: %#v %v", set, err)
   321  	}
   322  	var get syscall.Rlimit
   323  	err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &get)
   324  	if err != nil {
   325  		t.Fatalf("Getrlimit: get failed: %v", err)
   326  	}
   327  	set = rlimit
   328  	set.Cur = set.Max - 1
   329  	if set != get {
   330  		// Seems like Darwin requires some privilege to
   331  		// increase the soft limit of rlimit sandbox, though
   332  		// Setrlimit never reports an error.
   333  		switch runtime.GOOS {
   334  		case "darwin":
   335  		default:
   336  			t.Fatalf("Rlimit: change failed: wanted %#v got %#v", set, get)
   337  		}
   338  	}
   339  	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit)
   340  	if err != nil {
   341  		t.Fatalf("Setrlimit: restore failed: %#v %v", rlimit, err)
   342  	}
   343  }
   344  
   345  func TestSeekFailure(t *testing.T) {
   346  	_, err := syscall.Seek(-1, 0, io.SeekStart)
   347  	if err == nil {
   348  		t.Fatalf("Seek(-1, 0, 0) did not fail")
   349  	}
   350  	str := err.Error() // used to crash on Linux
   351  	t.Logf("Seek: %v", str)
   352  	if str == "" {
   353  		t.Fatalf("Seek(-1, 0, 0) return error with empty message")
   354  	}
   355  }
   356  

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