github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fs/host/wait_test.go (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package host
    16  
    17  import (
    18  	"testing"
    19  	"time"
    20  
    21  	"golang.org/x/sys/unix"
    22  	"github.com/SagerNet/gvisor/pkg/sentry/contexttest"
    23  	"github.com/SagerNet/gvisor/pkg/waiter"
    24  )
    25  
    26  func TestWait(t *testing.T) {
    27  	var fds [2]int
    28  	err := unix.Pipe(fds[:])
    29  	if err != nil {
    30  		t.Fatalf("Unable to create pipe: %v", err)
    31  	}
    32  
    33  	defer unix.Close(fds[1])
    34  
    35  	ctx := contexttest.Context(t)
    36  	file, err := NewFile(ctx, fds[0])
    37  	if err != nil {
    38  		unix.Close(fds[0])
    39  		t.Fatalf("NewFile failed: %v", err)
    40  	}
    41  
    42  	defer file.DecRef(ctx)
    43  
    44  	r := file.Readiness(waiter.ReadableEvents)
    45  	if r != 0 {
    46  		t.Fatalf("File is ready for read when it shouldn't be.")
    47  	}
    48  
    49  	e, ch := waiter.NewChannelEntry(nil)
    50  	file.EventRegister(&e, waiter.ReadableEvents)
    51  	defer file.EventUnregister(&e)
    52  
    53  	// Check that there are no notifications yet.
    54  	if len(ch) != 0 {
    55  		t.Fatalf("Channel is non-empty")
    56  	}
    57  
    58  	// Write to the pipe, so it should be writable now.
    59  	unix.Write(fds[1], []byte{1})
    60  
    61  	// Check that we get a notification. We need to yield the current thread
    62  	// so that the fdnotifier can deliver notifications, so we use a
    63  	// 1-second timeout instead of just checking the length of the channel.
    64  	select {
    65  	case <-ch:
    66  	case <-time.After(1 * time.Second):
    67  		t.Fatalf("Channel not notified")
    68  	}
    69  }