github.com/cilium/ebpf@v0.10.0/internal/sys/fd_test.go (about)

     1  package sys
     2  
     3  import (
     4  	"os"
     5  	"syscall"
     6  	"testing"
     7  
     8  	"github.com/cilium/ebpf/internal/unix"
     9  	qt "github.com/frankban/quicktest"
    10  )
    11  
    12  func init() {
    13  	// Free up fd 0 for TestFD.
    14  	stdin, err := unix.FcntlInt(os.Stdin.Fd(), unix.F_DUPFD_CLOEXEC, 1)
    15  	if err != nil {
    16  		panic(err)
    17  	}
    18  
    19  	old := os.Stdin
    20  	os.Stdin = os.NewFile(uintptr(stdin), "stdin")
    21  	old.Close()
    22  
    23  	reserveFdZero()
    24  }
    25  
    26  func reserveFdZero() {
    27  	fd, err := unix.Open(os.DevNull, syscall.O_RDONLY, 0)
    28  	if err != nil {
    29  		panic(err)
    30  	}
    31  	if fd != 0 {
    32  		panic(err)
    33  	}
    34  }
    35  
    36  func TestFD(t *testing.T) {
    37  	_, err := NewFD(-1)
    38  	qt.Assert(t, err, qt.IsNotNil, qt.Commentf("negative fd should be rejected"))
    39  
    40  	fd, err := NewFD(0)
    41  	qt.Assert(t, err, qt.IsNil)
    42  	qt.Assert(t, fd.Int(), qt.Not(qt.Equals), 0, qt.Commentf("fd value should not be zero"))
    43  
    44  	var stat unix.Stat_t
    45  	err = unix.Fstat(0, &stat)
    46  	qt.Assert(t, err, qt.ErrorIs, unix.EBADF, qt.Commentf("zero fd should be closed"))
    47  
    48  	reserveFdZero()
    49  }