pidfd_linux_test.go

     1  // Copyright 2023 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  package os_test
     6  
     7  import (
     8  	"errors"
     9  	"internal/syscall/unix"
    10  	"internal/testenv"
    11  	"os"
    12  	"os/exec"
    13  	"syscall"
    14  	"testing"
    15  )
    16  
    17  func TestFindProcessViaPidfd(t *testing.T) {
    18  	testenv.MustHaveGoBuild(t)
    19  	t.Parallel()
    20  
    21  	if err := os.CheckPidfdOnce(); err != nil {
    22  		// Non-pidfd code paths tested in exec_unix_test.go.
    23  		t.Skipf("skipping: pidfd not available: %v", err)
    24  	}
    25  
    26  	p, err := os.StartProcess(testenv.GoToolPath(t), []string{"go"}, &os.ProcAttr{})
    27  	if err != nil {
    28  		t.Fatalf("starting test process: %v", err)
    29  	}
    30  	p.Wait()
    31  
    32  	// Use pid of a non-existing process.
    33  	proc, err := os.FindProcess(p.Pid)
    34  	// FindProcess should never return errors on Unix.
    35  	if err != nil {
    36  		t.Fatalf("FindProcess: got error %v, want <nil>", err)
    37  	}
    38  	// FindProcess should never return nil Process.
    39  	if proc == nil {
    40  		t.Fatal("FindProcess: got nil, want non-nil")
    41  	}
    42  	if proc.Status() != os.StatusDone {
    43  		t.Fatalf("got process status: %v, want %d", proc.Status(), os.StatusDone)
    44  	}
    45  
    46  	// Check that all Process' public methods work as expected with
    47  	// "done" Process.
    48  	if err := proc.Kill(); err != os.ErrProcessDone {
    49  		t.Errorf("Kill: got %v, want %v", err, os.ErrProcessDone)
    50  	}
    51  	if err := proc.Signal(os.Kill); err != os.ErrProcessDone {
    52  		t.Errorf("Signal: got %v, want %v", err, os.ErrProcessDone)
    53  	}
    54  	if _, err := proc.Wait(); !errors.Is(err, syscall.ECHILD) {
    55  		t.Errorf("Wait: got %v, want %v", err, os.ErrProcessDone)
    56  	}
    57  	// Release never returns errors on Unix.
    58  	if err := proc.Release(); err != nil {
    59  		t.Fatalf("Release: got %v, want <nil>", err)
    60  	}
    61  }
    62  
    63  func TestStartProcessWithPidfd(t *testing.T) {
    64  	testenv.MustHaveGoBuild(t)
    65  	t.Parallel()
    66  
    67  	if err := os.CheckPidfdOnce(); err != nil {
    68  		// Non-pidfd code paths tested in exec_unix_test.go.
    69  		t.Skipf("skipping: pidfd not available: %v", err)
    70  	}
    71  
    72  	var pidfd int
    73  	p, err := os.StartProcess(testenv.GoToolPath(t), []string{"go"}, &os.ProcAttr{
    74  		Sys: &syscall.SysProcAttr{
    75  			PidFD: &pidfd,
    76  		},
    77  	})
    78  	if err != nil {
    79  		t.Fatalf("starting test process: %v", err)
    80  	}
    81  	defer syscall.Close(pidfd)
    82  
    83  	if _, err := p.Wait(); err != nil {
    84  		t.Fatalf("Wait: got %v, want <nil>", err)
    85  	}
    86  
    87  	// Check the pidfd is still valid
    88  	err = unix.PidFDSendSignal(uintptr(pidfd), syscall.Signal(0))
    89  	if !errors.Is(err, syscall.ESRCH) {
    90  		t.Errorf("SendSignal: got %v, want %v", err, syscall.ESRCH)
    91  	}
    92  }
    93  
    94  // Issue #69284
    95  func TestPidfdLeak(t *testing.T) {
    96  	testenv.MustHaveExec(t)
    97  	exe, err := os.Executable()
    98  	if err != nil {
    99  		t.Fatal(err)
   100  	}
   101  
   102  	// Find the next 10 descriptors.
   103  	// We need to get more than one descriptor in practice;
   104  	// the pidfd winds up not being the next descriptor.
   105  	const count = 10
   106  	want := make([]int, count)
   107  	for i := range count {
   108  		var err error
   109  		want[i], err = syscall.Open(exe, syscall.O_RDONLY, 0)
   110  		if err != nil {
   111  			t.Fatal(err)
   112  		}
   113  	}
   114  
   115  	// Close the descriptors.
   116  	for _, d := range want {
   117  		syscall.Close(d)
   118  	}
   119  
   120  	// Start a process 10 times.
   121  	for range 10 {
   122  		// For testing purposes this has to be an absolute path.
   123  		// Otherwise we will fail finding the executable
   124  		// and won't start a process at all.
   125  		cmd := exec.Command("/noSuchExecutable")
   126  		cmd.Run()
   127  	}
   128  
   129  	// Open the next 10 descriptors again.
   130  	got := make([]int, count)
   131  	for i := range count {
   132  		var err error
   133  		got[i], err = syscall.Open(exe, syscall.O_RDONLY, 0)
   134  		if err != nil {
   135  			t.Fatal(err)
   136  		}
   137  	}
   138  
   139  	// Close the descriptors
   140  	for _, d := range got {
   141  		syscall.Close(d)
   142  	}
   143  
   144  	t.Logf("got %v", got)
   145  	t.Logf("want %v", want)
   146  
   147  	// Allow some slack for runtime epoll descriptors and the like.
   148  	if got[count-1] > want[count-1]+5 {
   149  		t.Errorf("got descriptor %d, want %d", got[count-1], want[count-1])
   150  	}
   151  }
   152
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