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// Copyright 2023 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package devutil provides device specific utilities.
package devutil
import (
"fmt"
"golang.org/x/sys/unix"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/fsutil"
"gvisor.dev/gvisor/pkg/lisafs"
"gvisor.dev/gvisor/pkg/log"
"gvisor.dev/gvisor/pkg/unet"
)
// GoferClient is the lisafs client for the /dev gofer connection.
type GoferClient struct {
clientFD lisafs.ClientFD
hostFD int
contName string
}
// NewGoferClient establishes the LISAFS connection to the dev gofer server.
// It takes ownership of fd. contName is the owning container name.
func NewGoferClient(ctx context.Context, contName string, fd int) (*GoferClient, error) {
ctx.UninterruptibleSleepStart(false)
defer ctx.UninterruptibleSleepFinish(false)
sock, err := unet.NewSocket(fd)
if err != nil {
ctx.Warningf("failed to create socket for dev gofer client: %v", err)
return nil, err
}
client, devInode, devHostFD, err := lisafs.NewClient(sock)
if err != nil {
ctx.Warningf("failed to create dev gofer client: %v", err)
return nil, err
}
return &GoferClient{
clientFD: client.NewFD(devInode.ControlFD),
hostFD: devHostFD,
contName: contName,
}, nil
}
// Close closes the LISAFS connection.
func (g *GoferClient) Close() {
// Close the connection to the server. This implicitly closes all FDs.
g.clientFD.Client().Close()
if g.hostFD >= 0 {
_ = unix.Close(g.hostFD)
}
}
// ContainerName returns the name of the container that owns this gofer.
func (g *GoferClient) ContainerName() string {
return g.contName
}
// DirentNames returns names of all the dirents for /dev on the gofer.
func (g *GoferClient) DirentNames(ctx context.Context) ([]string, error) {
if g.hostFD >= 0 {
return fsutil.DirentNames(g.hostFD)
}
client := g.clientFD.Client()
openFDID, _, err := g.clientFD.OpenAt(ctx, unix.O_RDONLY)
if err != nil {
return nil, fmt.Errorf("failed to open dev from gofer: %v", err)
}
defer client.CloseFD(ctx, openFDID, true /* flush */)
openFD := client.NewFD(openFDID)
const count = int32(64 * 1024)
var names []string
for {
dirents, err := openFD.Getdents64(ctx, count)
if err != nil {
return nil, fmt.Errorf("Getdents64 RPC failed: %v", err)
}
if len(dirents) == 0 {
break
}
for i := range dirents {
names = append(names, string(dirents[i].Name))
}
}
return names, nil
}
// OpenAt opens the device file at /dev/{name} on the gofer.
func (g *GoferClient) OpenAt(ctx context.Context, name string, flags uint32) (int, error) {
flags &= unix.O_ACCMODE
if g.hostFD >= 0 {
return unix.Openat(g.hostFD, name, int(flags|unix.O_NOFOLLOW), 0)
}
childInode, err := g.clientFD.Walk(ctx, name)
if err != nil {
log.Infof("failed to walk %q from dev gofer FD", name)
return 0, err
}
client := g.clientFD.Client()
childFD := client.NewFD(childInode.ControlFD)
childOpenFD, childHostFD, err := childFD.OpenAt(ctx, flags)
if err != nil {
log.Infof("failed to open %q from child FD", name)
client.CloseFD(ctx, childFD.ID(), true /* flush */)
return 0, err
}
client.CloseFD(ctx, childFD.ID(), false /* flush */)
client.CloseFD(ctx, childOpenFD, true /* flush */)
return childHostFD, nil
}
// GoferClientProvider provides a GoferClient for a given container.
type GoferClientProvider interface {
GetDevGoferClient(contName string) *GoferClient
}
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