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Source file src/syscall/syscall_linux_test.go

Documentation: syscall

  // Copyright 2015 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.
  
  package syscall_test
  
  import (
  	"bufio"
  	"fmt"
  	"io"
  	"io/ioutil"
  	"os"
  	"os/exec"
  	"os/signal"
  	"path/filepath"
  	"runtime"
  	"strconv"
  	"strings"
  	"syscall"
  	"testing"
  	"time"
  )
  
  // chtmpdir changes the working directory to a new temporary directory and
  // provides a cleanup function. Used when PWD is read-only.
  func chtmpdir(t *testing.T) func() {
  	oldwd, err := os.Getwd()
  	if err != nil {
  		t.Fatalf("chtmpdir: %v", err)
  	}
  	d, err := ioutil.TempDir("", "test")
  	if err != nil {
  		t.Fatalf("chtmpdir: %v", err)
  	}
  	if err := os.Chdir(d); err != nil {
  		t.Fatalf("chtmpdir: %v", err)
  	}
  	return func() {
  		if err := os.Chdir(oldwd); err != nil {
  			t.Fatalf("chtmpdir: %v", err)
  		}
  		os.RemoveAll(d)
  	}
  }
  
  func touch(t *testing.T, name string) {
  	f, err := os.Create(name)
  	if err != nil {
  		t.Fatal(err)
  	}
  	if err := f.Close(); err != nil {
  		t.Fatal(err)
  	}
  }
  
  const (
  	_AT_SYMLINK_NOFOLLOW = 0x100
  	_AT_FDCWD            = -0x64
  	_AT_EACCESS          = 0x200
  	_F_OK                = 0
  	_R_OK                = 4
  )
  
  func TestFaccessat(t *testing.T) {
  	defer chtmpdir(t)()
  	touch(t, "file1")
  
  	err := syscall.Faccessat(_AT_FDCWD, "file1", _R_OK, 0)
  	if err != nil {
  		t.Errorf("Faccessat: unexpected error: %v", err)
  	}
  
  	err = syscall.Faccessat(_AT_FDCWD, "file1", _R_OK, 2)
  	if err != syscall.EINVAL {
  		t.Errorf("Faccessat: unexpected error: %v, want EINVAL", err)
  	}
  
  	err = syscall.Faccessat(_AT_FDCWD, "file1", _R_OK, _AT_EACCESS)
  	if err != nil {
  		t.Errorf("Faccessat: unexpected error: %v", err)
  	}
  
  	err = os.Symlink("file1", "symlink1")
  	if err != nil {
  		t.Fatal(err)
  	}
  
  	err = syscall.Faccessat(_AT_FDCWD, "symlink1", _R_OK, _AT_SYMLINK_NOFOLLOW)
  	if err != nil {
  		t.Errorf("Faccessat SYMLINK_NOFOLLOW: unexpected error %v", err)
  	}
  
  	// We can't really test _AT_SYMLINK_NOFOLLOW, because there
  	// doesn't seem to be any way to change the mode of a symlink.
  	// We don't test _AT_EACCESS because such tests are only
  	// meaningful if run as root.
  
  	err = syscall.Fchmodat(_AT_FDCWD, "file1", 0, 0)
  	if err != nil {
  		t.Errorf("Fchmodat: unexpected error %v", err)
  	}
  
  	err = syscall.Faccessat(_AT_FDCWD, "file1", _F_OK, _AT_SYMLINK_NOFOLLOW)
  	if err != nil {
  		t.Errorf("Faccessat: unexpected error: %v", err)
  	}
  
  	err = syscall.Faccessat(_AT_FDCWD, "file1", _R_OK, _AT_SYMLINK_NOFOLLOW)
  	if err != syscall.EACCES {
  		if syscall.Getuid() != 0 {
  			t.Errorf("Faccessat: unexpected error: %v, want EACCES", err)
  		}
  	}
  }
  
  func TestFchmodat(t *testing.T) {
  	defer chtmpdir(t)()
  
  	touch(t, "file1")
  	os.Symlink("file1", "symlink1")
  
  	err := syscall.Fchmodat(_AT_FDCWD, "symlink1", 0444, 0)
  	if err != nil {
  		t.Fatalf("Fchmodat: unexpected error: %v", err)
  	}
  
  	fi, err := os.Stat("file1")
  	if err != nil {
  		t.Fatal(err)
  	}
  
  	if fi.Mode() != 0444 {
  		t.Errorf("Fchmodat: failed to change mode: expected %v, got %v", 0444, fi.Mode())
  	}
  
  	err = syscall.Fchmodat(_AT_FDCWD, "symlink1", 0444, _AT_SYMLINK_NOFOLLOW)
  	if err != syscall.EOPNOTSUPP {
  		t.Fatalf("Fchmodat: unexpected error: %v, expected EOPNOTSUPP", err)
  	}
  }
  
  func TestMain(m *testing.M) {
  	if os.Getenv("GO_DEATHSIG_PARENT") == "1" {
  		deathSignalParent()
  	} else if os.Getenv("GO_DEATHSIG_CHILD") == "1" {
  		deathSignalChild()
  	} else if os.Getenv("GO_SYSCALL_NOERROR") == "1" {
  		syscallNoError()
  	}
  
  	os.Exit(m.Run())
  }
  
  func TestLinuxDeathSignal(t *testing.T) {
  	if os.Getuid() != 0 {
  		t.Skip("skipping root only test")
  	}
  
  	// Copy the test binary to a location that a non-root user can read/execute
  	// after we drop privileges
  	tempDir, err := ioutil.TempDir("", "TestDeathSignal")
  	if err != nil {
  		t.Fatalf("cannot create temporary directory: %v", err)
  	}
  	defer os.RemoveAll(tempDir)
  	os.Chmod(tempDir, 0755)
  
  	tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
  
  	src, err := os.Open(os.Args[0])
  	if err != nil {
  		t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
  	}
  	defer src.Close()
  
  	dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
  	if err != nil {
  		t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
  	}
  	if _, err := io.Copy(dst, src); err != nil {
  		t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
  	}
  	err = dst.Close()
  	if err != nil {
  		t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
  	}
  
  	cmd := exec.Command(tmpBinary)
  	cmd.Env = []string{"GO_DEATHSIG_PARENT=1"}
  	chldStdin, err := cmd.StdinPipe()
  	if err != nil {
  		t.Fatalf("failed to create new stdin pipe: %v", err)
  	}
  	chldStdout, err := cmd.StdoutPipe()
  	if err != nil {
  		t.Fatalf("failed to create new stdout pipe: %v", err)
  	}
  	cmd.Stderr = os.Stderr
  
  	err = cmd.Start()
  	defer cmd.Wait()
  	if err != nil {
  		t.Fatalf("failed to start first child process: %v", err)
  	}
  
  	chldPipe := bufio.NewReader(chldStdout)
  
  	if got, err := chldPipe.ReadString('\n'); got == "start\n" {
  		syscall.Kill(cmd.Process.Pid, syscall.SIGTERM)
  
  		go func() {
  			time.Sleep(5 * time.Second)
  			chldStdin.Close()
  		}()
  
  		want := "ok\n"
  		if got, err = chldPipe.ReadString('\n'); got != want {
  			t.Fatalf("expected %q, received %q, %v", want, got, err)
  		}
  	} else {
  		t.Fatalf("did not receive start from child, received %q, %v", got, err)
  	}
  }
  
  func deathSignalParent() {
  	cmd := exec.Command(os.Args[0])
  	cmd.Env = []string{"GO_DEATHSIG_CHILD=1"}
  	cmd.Stdin = os.Stdin
  	cmd.Stdout = os.Stdout
  	attrs := syscall.SysProcAttr{
  		Pdeathsig: syscall.SIGUSR1,
  		// UID/GID 99 is the user/group "nobody" on RHEL/Fedora and is
  		// unused on Ubuntu
  		Credential: &syscall.Credential{Uid: 99, Gid: 99},
  	}
  	cmd.SysProcAttr = &attrs
  
  	err := cmd.Start()
  	if err != nil {
  		fmt.Fprintf(os.Stderr, "death signal parent error: %v\n", err)
  		os.Exit(1)
  	}
  	cmd.Wait()
  	os.Exit(0)
  }
  
  func deathSignalChild() {
  	c := make(chan os.Signal, 1)
  	signal.Notify(c, syscall.SIGUSR1)
  	go func() {
  		<-c
  		fmt.Println("ok")
  		os.Exit(0)
  	}()
  	fmt.Println("start")
  
  	buf := make([]byte, 32)
  	os.Stdin.Read(buf)
  
  	// We expected to be signaled before stdin closed
  	fmt.Println("not ok")
  	os.Exit(1)
  }
  
  func TestParseNetlinkMessage(t *testing.T) {
  	for i, b := range [][]byte{
  		{103, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 5, 8, 0, 3,
  			0, 8, 0, 6, 0, 0, 0, 0, 1, 63, 0, 10, 0, 69, 16, 0, 59, 39, 82, 64, 0, 64, 6, 21, 89, 127, 0, 0,
  			1, 127, 0, 0, 1, 230, 228, 31, 144, 32, 186, 155, 211, 185, 151, 209, 179, 128, 24, 1, 86,
  			53, 119, 0, 0, 1, 1, 8, 10, 0, 17, 234, 12, 0, 17, 189, 126, 107, 106, 108, 107, 106, 13, 10,
  		},
  		{106, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 3, 8, 0, 3,
  			0, 8, 0, 6, 0, 0, 0, 0, 1, 66, 0, 10, 0, 69, 0, 0, 62, 230, 255, 64, 0, 64, 6, 85, 184, 127, 0, 0,
  			1, 127, 0, 0, 1, 237, 206, 31, 144, 73, 197, 128, 65, 250, 60, 192, 97, 128, 24, 1, 86, 253, 21, 0,
  			0, 1, 1, 8, 10, 0, 51, 106, 89, 0, 51, 102, 198, 108, 104, 106, 108, 107, 104, 108, 107, 104, 10,
  		},
  		{102, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 11, 0, 1, 0, 0, 0, 0, 1, 8, 0, 3, 0,
  			8, 0, 6, 0, 0, 0, 0, 1, 62, 0, 10, 0, 69, 0, 0, 58, 231, 2, 64, 0, 64, 6, 85, 185, 127, 0, 0, 1, 127,
  			0, 0, 1, 237, 206, 31, 144, 73, 197, 128, 86, 250, 60, 192, 97, 128, 24, 1, 86, 104, 64, 0, 0, 1, 1, 8,
  			10, 0, 52, 198, 200, 0, 51, 135, 232, 101, 115, 97, 103, 103, 10,
  		},
  	} {
  		m, err := syscall.ParseNetlinkMessage(b)
  		if err != syscall.EINVAL {
  			t.Errorf("#%d: got %v; want EINVAL", i, err)
  		}
  		if m != nil {
  			t.Errorf("#%d: got %v; want nil", i, m)
  		}
  	}
  }
  
  func TestSyscallNoError(t *testing.T) {
  	// On Linux there are currently no syscalls which don't fail and return
  	// a value larger than 0xfffffffffffff001 so we could test RawSyscall
  	// vs. RawSyscallNoError on 64bit architectures.
  	if runtime.GOARCH != "386" && runtime.GOARCH != "arm" {
  		t.Skip("skipping on non-32bit architecture")
  	}
  
  	if os.Getuid() != 0 {
  		t.Skip("skipping root only test")
  	}
  
  	// Copy the test binary to a location that a non-root user can read/execute
  	// after we drop privileges
  	tempDir, err := ioutil.TempDir("", "TestSyscallNoError")
  	if err != nil {
  		t.Fatalf("cannot create temporary directory: %v", err)
  	}
  	defer os.RemoveAll(tempDir)
  	os.Chmod(tempDir, 0755)
  
  	tmpBinary := filepath.Join(tempDir, filepath.Base(os.Args[0]))
  
  	src, err := os.Open(os.Args[0])
  	if err != nil {
  		t.Fatalf("cannot open binary %q, %v", os.Args[0], err)
  	}
  	defer src.Close()
  
  	dst, err := os.OpenFile(tmpBinary, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0755)
  	if err != nil {
  		t.Fatalf("cannot create temporary binary %q, %v", tmpBinary, err)
  	}
  	if _, err := io.Copy(dst, src); err != nil {
  		t.Fatalf("failed to copy test binary to %q, %v", tmpBinary, err)
  	}
  	err = dst.Close()
  	if err != nil {
  		t.Fatalf("failed to close test binary %q, %v", tmpBinary, err)
  	}
  
  	uid := uint32(0xfffffffe)
  	err = os.Chown(tmpBinary, int(uid), -1)
  	if err != nil {
  		t.Fatalf("failed to chown test binary %q, %v", tmpBinary, err)
  	}
  
  	err = os.Chmod(tmpBinary, 0755|os.ModeSetuid)
  	if err != nil {
  		t.Fatalf("failed to set setuid bit on test binary %q, %v", tmpBinary, err)
  	}
  
  	cmd := exec.Command(tmpBinary)
  	cmd.Env = []string{"GO_SYSCALL_NOERROR=1"}
  
  	out, err := cmd.CombinedOutput()
  	if err != nil {
  		t.Fatalf("failed to start first child process: %v", err)
  	}
  
  	got := strings.TrimSpace(string(out))
  	want := strconv.FormatUint(uint64(uid)+1, 10) + " / " +
  		strconv.FormatUint(uint64(-uid), 10) + " / " +
  		strconv.FormatUint(uint64(uid), 10)
  	if got != want {
  		t.Errorf("expected %s, got %s", want, got)
  	}
  }
  
  func syscallNoError() {
  	// Test that the return value from SYS_GETEUID32 (which cannot fail)
  	// doesn't get treated as an error (see https://golang.org/issue/22924)
  	euid1, _, e := syscall.RawSyscall(syscall.Sys_GETEUID, 0, 0, 0)
  	euid2, _ := syscall.RawSyscallNoError(syscall.Sys_GETEUID, 0, 0, 0)
  
  	fmt.Println(uintptr(euid1), "/", int(e), "/", uintptr(euid2))
  	os.Exit(0)
  }
  

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