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Source file src/syscall/syscall_unix_test.go

Documentation: syscall

  // Copyright 2013 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // +build darwin dragonfly freebsd linux netbsd openbsd solaris
  
  package syscall_test
  
  import (
  	"flag"
  	"fmt"
  	"internal/testenv"
  	"io"
  	"io/ioutil"
  	"net"
  	"os"
  	"os/exec"
  	"path/filepath"
  	"runtime"
  	"syscall"
  	"testing"
  	"time"
  )
  
  // Tests that below functions, structures and constants are consistent
  // on all Unix-like systems.
  func _() {
  	// program scheduling priority functions and constants
  	var (
  		_ func(int, int, int) error   = syscall.Setpriority
  		_ func(int, int) (int, error) = syscall.Getpriority
  	)
  	const (
  		_ int = syscall.PRIO_USER
  		_ int = syscall.PRIO_PROCESS
  		_ int = syscall.PRIO_PGRP
  	)
  
  	// termios constants
  	const (
  		_ int = syscall.TCIFLUSH
  		_ int = syscall.TCIOFLUSH
  		_ int = syscall.TCOFLUSH
  	)
  
  	// fcntl file locking structure and constants
  	var (
  		_ = syscall.Flock_t{
  			Type:   int16(0),
  			Whence: int16(0),
  			Start:  int64(0),
  			Len:    int64(0),
  			Pid:    int32(0),
  		}
  	)
  	const (
  		_ = syscall.F_GETLK
  		_ = syscall.F_SETLK
  		_ = syscall.F_SETLKW
  	)
  }
  
  // TestFcntlFlock tests whether the file locking structure matches
  // the calling convention of each kernel.
  // On some Linux systems, glibc uses another set of values for the
  // commands and translates them to the correct value that the kernel
  // expects just before the actual fcntl syscall. As Go uses raw
  // syscalls directly, it must use the real value, not the glibc value.
  // Thus this test also verifies that the Flock_t structure can be
  // roundtripped with F_SETLK and F_GETLK.
  func TestFcntlFlock(t *testing.T) {
  	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
  		t.Skip("skipping; no child processes allowed on iOS")
  	}
  	flock := syscall.Flock_t{
  		Type:  syscall.F_WRLCK,
  		Start: 31415, Len: 271828, Whence: 1,
  	}
  	if os.Getenv("GO_WANT_HELPER_PROCESS") == "" {
  		// parent
  		tempDir, err := ioutil.TempDir("", "TestFcntlFlock")
  		if err != nil {
  			t.Fatalf("Failed to create temp dir: %v", err)
  		}
  		name := filepath.Join(tempDir, "TestFcntlFlock")
  		fd, err := syscall.Open(name, syscall.O_CREAT|syscall.O_RDWR|syscall.O_CLOEXEC, 0)
  		if err != nil {
  			t.Fatalf("Open failed: %v", err)
  		}
  		defer os.RemoveAll(tempDir)
  		defer syscall.Close(fd)
  		if err := syscall.Ftruncate(fd, 1<<20); err != nil {
  			t.Fatalf("Ftruncate(1<<20) failed: %v", err)
  		}
  		if err := syscall.FcntlFlock(uintptr(fd), syscall.F_SETLK, &flock); err != nil {
  			t.Fatalf("FcntlFlock(F_SETLK) failed: %v", err)
  		}
  		cmd := exec.Command(os.Args[0], "-test.run=^TestFcntlFlock$")
  		cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
  		cmd.ExtraFiles = []*os.File{os.NewFile(uintptr(fd), name)}
  		out, err := cmd.CombinedOutput()
  		if len(out) > 0 || err != nil {
  			t.Fatalf("child process: %q, %v", out, err)
  		}
  	} else {
  		// child
  		got := flock
  		// make sure the child lock is conflicting with the parent lock
  		got.Start--
  		got.Len++
  		if err := syscall.FcntlFlock(3, syscall.F_GETLK, &got); err != nil {
  			t.Fatalf("FcntlFlock(F_GETLK) failed: %v", err)
  		}
  		flock.Pid = int32(syscall.Getppid())
  		// Linux kernel always set Whence to 0
  		flock.Whence = 0
  		if got.Type == flock.Type && got.Start == flock.Start && got.Len == flock.Len && got.Pid == flock.Pid && got.Whence == flock.Whence {
  			os.Exit(0)
  		}
  		t.Fatalf("FcntlFlock got %v, want %v", got, flock)
  	}
  }
  
  // TestPassFD tests passing a file descriptor over a Unix socket.
  //
  // This test involved both a parent and child process. The parent
  // process is invoked as a normal test, with "go test", which then
  // runs the child process by running the current test binary with args
  // "-test.run=^TestPassFD$" and an environment variable used to signal
  // that the test should become the child process instead.
  func TestPassFD(t *testing.T) {
  	testenv.MustHaveExec(t)
  
  	if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
  		passFDChild()
  		return
  	}
  
  	tempDir, err := ioutil.TempDir("", "TestPassFD")
  	if err != nil {
  		t.Fatal(err)
  	}
  	defer os.RemoveAll(tempDir)
  
  	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
  	if err != nil {
  		t.Fatalf("Socketpair: %v", err)
  	}
  	defer syscall.Close(fds[0])
  	defer syscall.Close(fds[1])
  	writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
  	readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
  	defer writeFile.Close()
  	defer readFile.Close()
  
  	cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
  	cmd.Env = append(os.Environ(), "GO_WANT_HELPER_PROCESS=1")
  	cmd.ExtraFiles = []*os.File{writeFile}
  
  	out, err := cmd.CombinedOutput()
  	if len(out) > 0 || err != nil {
  		t.Fatalf("child process: %q, %v", out, err)
  	}
  
  	c, err := net.FileConn(readFile)
  	if err != nil {
  		t.Fatalf("FileConn: %v", err)
  	}
  	defer c.Close()
  
  	uc, ok := c.(*net.UnixConn)
  	if !ok {
  		t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
  	}
  
  	buf := make([]byte, 32) // expect 1 byte
  	oob := make([]byte, 32) // expect 24 bytes
  	closeUnix := time.AfterFunc(5*time.Second, func() {
  		t.Logf("timeout reading from unix socket")
  		uc.Close()
  	})
  	_, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
  	closeUnix.Stop()
  
  	scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
  	if err != nil {
  		t.Fatalf("ParseSocketControlMessage: %v", err)
  	}
  	if len(scms) != 1 {
  		t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
  	}
  	scm := scms[0]
  	gotFds, err := syscall.ParseUnixRights(&scm)
  	if err != nil {
  		t.Fatalf("syscall.ParseUnixRights: %v", err)
  	}
  	if len(gotFds) != 1 {
  		t.Fatalf("wanted 1 fd; got %#v", gotFds)
  	}
  
  	f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
  	defer f.Close()
  
  	got, err := ioutil.ReadAll(f)
  	want := "Hello from child process!\n"
  	if string(got) != want {
  		t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
  	}
  }
  
  // passFDChild is the child process used by TestPassFD.
  func passFDChild() {
  	defer os.Exit(0)
  
  	// Look for our fd. It should be fd 3, but we work around an fd leak
  	// bug here (https://golang.org/issue/2603) to let it be elsewhere.
  	var uc *net.UnixConn
  	for fd := uintptr(3); fd <= 10; fd++ {
  		f := os.NewFile(fd, "unix-conn")
  		var ok bool
  		netc, _ := net.FileConn(f)
  		uc, ok = netc.(*net.UnixConn)
  		if ok {
  			break
  		}
  	}
  	if uc == nil {
  		fmt.Println("failed to find unix fd")
  		return
  	}
  
  	// Make a file f to send to our parent process on uc.
  	// We make it in tempDir, which our parent will clean up.
  	flag.Parse()
  	tempDir := flag.Arg(0)
  	f, err := ioutil.TempFile(tempDir, "")
  	if err != nil {
  		fmt.Printf("TempFile: %v", err)
  		return
  	}
  
  	f.Write([]byte("Hello from child process!\n"))
  	f.Seek(0, io.SeekStart)
  
  	rights := syscall.UnixRights(int(f.Fd()))
  	dummyByte := []byte("x")
  	n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
  	if err != nil {
  		fmt.Printf("WriteMsgUnix: %v", err)
  		return
  	}
  	if n != 1 || oobn != len(rights) {
  		fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
  		return
  	}
  }
  
  // TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage,
  // and ParseUnixRights are able to successfully round-trip lists of file descriptors.
  func TestUnixRightsRoundtrip(t *testing.T) {
  	testCases := [...][][]int{
  		{{42}},
  		{{1, 2}},
  		{{3, 4, 5}},
  		{{}},
  		{{1, 2}, {3, 4, 5}, {}, {7}},
  	}
  	for _, testCase := range testCases {
  		b := []byte{}
  		var n int
  		for _, fds := range testCase {
  			// Last assignment to n wins
  			n = len(b) + syscall.CmsgLen(4*len(fds))
  			b = append(b, syscall.UnixRights(fds...)...)
  		}
  		// Truncate b
  		b = b[:n]
  
  		scms, err := syscall.ParseSocketControlMessage(b)
  		if err != nil {
  			t.Fatalf("ParseSocketControlMessage: %v", err)
  		}
  		if len(scms) != len(testCase) {
  			t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
  		}
  		for i, scm := range scms {
  			gotFds, err := syscall.ParseUnixRights(&scm)
  			if err != nil {
  				t.Fatalf("ParseUnixRights: %v", err)
  			}
  			wantFds := testCase[i]
  			if len(gotFds) != len(wantFds) {
  				t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
  			}
  			for j, fd := range gotFds {
  				if fd != wantFds[j] {
  					t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
  				}
  			}
  		}
  	}
  }
  
  func TestRlimit(t *testing.T) {
  	var rlimit, zero syscall.Rlimit
  	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlimit)
  	if err != nil {
  		t.Fatalf("Getrlimit: save failed: %v", err)
  	}
  	if zero == rlimit {
  		t.Fatalf("Getrlimit: save failed: got zero value %#v", rlimit)
  	}
  	set := rlimit
  	set.Cur = set.Max - 1
  	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &set)
  	if err != nil {
  		t.Fatalf("Setrlimit: set failed: %#v %v", set, err)
  	}
  	var get syscall.Rlimit
  	err = syscall.Getrlimit(syscall.RLIMIT_NOFILE, &get)
  	if err != nil {
  		t.Fatalf("Getrlimit: get failed: %v", err)
  	}
  	set = rlimit
  	set.Cur = set.Max - 1
  	if set != get {
  		// Seems like Darwin requires some privilege to
  		// increase the soft limit of rlimit sandbox, though
  		// Setrlimit never reports an error.
  		switch runtime.GOOS {
  		case "darwin":
  		default:
  			t.Fatalf("Rlimit: change failed: wanted %#v got %#v", set, get)
  		}
  	}
  	err = syscall.Setrlimit(syscall.RLIMIT_NOFILE, &rlimit)
  	if err != nil {
  		t.Fatalf("Setrlimit: restore failed: %#v %v", rlimit, err)
  	}
  }
  
  func TestSeekFailure(t *testing.T) {
  	_, err := syscall.Seek(-1, 0, io.SeekStart)
  	if err == nil {
  		t.Fatalf("Seek(-1, 0, 0) did not fail")
  	}
  	str := err.Error() // used to crash on Linux
  	t.Logf("Seek: %v", str)
  	if str == "" {
  		t.Fatalf("Seek(-1, 0, 0) return error with empty message")
  	}
  }
  

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