github.com/containerd/containerd@v22.0.0-20200918172823-438c87b8e050+incompatible/runtime/v2/shim/util_unix.go (about)

     1  // +build !windows
     2  
     3  /*
     4     Copyright The containerd Authors.
     5  
     6     Licensed under the Apache License, Version 2.0 (the "License");
     7     you may not use this file except in compliance with the License.
     8     You may obtain a copy of the License at
     9  
    10         http://www.apache.org/licenses/LICENSE-2.0
    11  
    12     Unless required by applicable law or agreed to in writing, software
    13     distributed under the License is distributed on an "AS IS" BASIS,
    14     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15     See the License for the specific language governing permissions and
    16     limitations under the License.
    17  */
    18  
    19  package shim
    20  
    21  import (
    22  	"context"
    23  	"crypto/sha256"
    24  	"fmt"
    25  	"net"
    26  	"os"
    27  	"path/filepath"
    28  	"strings"
    29  	"syscall"
    30  	"time"
    31  
    32  	"github.com/containerd/containerd/namespaces"
    33  	"github.com/containerd/containerd/pkg/dialer"
    34  	"github.com/containerd/containerd/sys"
    35  	"github.com/pkg/errors"
    36  )
    37  
    38  const shimBinaryFormat = "containerd-shim-%s-%s"
    39  
    40  func getSysProcAttr() *syscall.SysProcAttr {
    41  	return &syscall.SysProcAttr{
    42  		Setpgid: true,
    43  	}
    44  }
    45  
    46  // SetScore sets the oom score for a process
    47  func SetScore(pid int) error {
    48  	return sys.SetOOMScore(pid, sys.OOMScoreMaxKillable)
    49  }
    50  
    51  // AdjustOOMScore sets the OOM score for the process to the parents OOM score +1
    52  // to ensure that they parent has a lower* score than the shim
    53  func AdjustOOMScore(pid int) error {
    54  	parent := os.Getppid()
    55  	score, err := sys.GetOOMScoreAdj(parent)
    56  	if err != nil {
    57  		return errors.Wrap(err, "get parent OOM score")
    58  	}
    59  	shimScore := score + 1
    60  	if err := sys.SetOOMScore(pid, shimScore); err != nil {
    61  		return errors.Wrap(err, "set shim OOM score")
    62  	}
    63  	return nil
    64  }
    65  
    66  // SocketAddress returns an abstract socket address
    67  func SocketAddress(ctx context.Context, id string) (string, error) {
    68  	ns, err := namespaces.NamespaceRequired(ctx)
    69  	if err != nil {
    70  		return "", err
    71  	}
    72  	d := sha256.Sum256([]byte(filepath.Join(ns, id)))
    73  	return filepath.Join(string(filepath.Separator), "containerd-shim", fmt.Sprintf("%x.sock", d)), nil
    74  }
    75  
    76  // AnonDialer returns a dialer for an abstract socket
    77  func AnonDialer(address string, timeout time.Duration) (net.Conn, error) {
    78  	address = strings.TrimPrefix(address, "unix://")
    79  	return dialer.Dialer("\x00"+address, timeout)
    80  }
    81  
    82  func AnonReconnectDialer(address string, timeout time.Duration) (net.Conn, error) {
    83  	return AnonDialer(address, timeout)
    84  }
    85  
    86  // NewSocket returns a new socket
    87  func NewSocket(address string) (*net.UnixListener, error) {
    88  	if len(address) > 106 {
    89  		return nil, errors.Errorf("%q: unix socket path too long (> 106)", address)
    90  	}
    91  	l, err := net.Listen("unix", "\x00"+address)
    92  	if err != nil {
    93  		return nil, errors.Wrapf(err, "failed to listen to abstract unix socket %q", address)
    94  	}
    95  	return l.(*net.UnixListener), nil
    96  }