github.com/metacubex/gvisor@v0.0.0-20240320004321-933faba989ec/runsc/boot/portforward/portforward_fd_rw.go (about)

     1  // Copyright 2022 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 portforward
    16  
    17  import (
    18  	"io"
    19  	"sync"
    20  
    21  	"github.com/metacubex/gvisor/pkg/context"
    22  	"github.com/metacubex/gvisor/pkg/errors/linuxerr"
    23  	"github.com/metacubex/gvisor/pkg/sentry/vfs"
    24  	"github.com/metacubex/gvisor/pkg/usermem"
    25  	"github.com/metacubex/gvisor/pkg/waiter"
    26  )
    27  
    28  // fileDescriptionConn
    29  type fileDescriptionConn struct {
    30  	// file is the file to read and write from.
    31  	file *vfs.FileDescription
    32  	// once makes sure we release the owned FileDescription once.
    33  	once sync.Once
    34  }
    35  
    36  // NewFileDescriptionConn initializes a fileDescriptionConn.
    37  func NewFileDescriptionConn(file *vfs.FileDescription) proxyConn {
    38  	return &fileDescriptionConn{file: file}
    39  }
    40  
    41  // Name implements proxyConn.Name.
    42  func (r *fileDescriptionConn) Name() string {
    43  	return "fileDescriptionConn"
    44  }
    45  
    46  // Read implements proxyConn.Read.
    47  func (r *fileDescriptionConn) Read(ctx context.Context, buf []byte, cancel <-chan struct{}) (int, error) {
    48  	var (
    49  		notifyCh  chan struct{}
    50  		waitEntry waiter.Entry
    51  	)
    52  	n, err := r.file.Read(ctx, usermem.BytesIOSequence(buf), vfs.ReadOptions{})
    53  	for linuxerr.Equals(linuxerr.ErrWouldBlock, err) {
    54  		if notifyCh == nil {
    55  			waitEntry, notifyCh = waiter.NewChannelEntry(waiter.ReadableEvents | waiter.WritableEvents | waiter.EventHUp | waiter.EventErr)
    56  			// Register for when the endpoint is readable or disconnected.
    57  			r.file.EventRegister(&waitEntry)
    58  			defer r.file.EventUnregister(&waitEntry)
    59  		}
    60  		select {
    61  		case <-notifyCh:
    62  		case <-cancel:
    63  			return 0, io.EOF
    64  		}
    65  		n, err = r.file.Read(ctx, usermem.BytesIOSequence(buf), vfs.ReadOptions{})
    66  	}
    67  
    68  	// host fd FileDescriptions use recvmsg which returns zero when the
    69  	// peer has shutdown. When that happens return EOF.
    70  	if n == 0 && err == nil {
    71  		return 0, io.EOF
    72  	}
    73  	return int(n), err
    74  }
    75  
    76  // Write implements proxyConn.Write.
    77  func (r *fileDescriptionConn) Write(ctx context.Context, buf []byte, cancel <-chan struct{}) (int, error) {
    78  	var notifyCh chan struct{}
    79  	var waitEntry waiter.Entry
    80  	n, err := r.file.Write(ctx, usermem.BytesIOSequence(buf), vfs.WriteOptions{})
    81  	for linuxerr.Equals(linuxerr.ErrWouldBlock, err) {
    82  		if notifyCh == nil {
    83  			waitEntry, notifyCh = waiter.NewChannelEntry(waiter.WritableEvents | waiter.EventHUp | waiter.EventErr)
    84  			// Register for when the endpoint is writable or disconnected.
    85  			r.file.EventRegister(&waitEntry)
    86  			defer r.file.EventUnregister(&waitEntry)
    87  		}
    88  		select {
    89  		case <-notifyCh:
    90  		case <-cancel:
    91  			return 0, io.EOF
    92  		}
    93  		n, err = r.file.Write(ctx, usermem.BytesIOSequence(buf), vfs.WriteOptions{})
    94  	}
    95  	return int(n), err
    96  }
    97  
    98  // Close implements proxyConn.Close.
    99  func (r *fileDescriptionConn) Close(ctx context.Context) {
   100  	r.once.Do(func() {
   101  		r.file.DecRef(ctx)
   102  	})
   103  }