github.com/containerd/containerd@v22.0.0-20200918172823-438c87b8e050+incompatible/signals.go (about) 1 /* 2 Copyright The containerd Authors. 3 4 Licensed under the Apache License, Version 2.0 (the "License"); 5 you may not use this file except in compliance with the License. 6 You may obtain a copy of the License at 7 8 http://www.apache.org/licenses/LICENSE-2.0 9 10 Unless required by applicable law or agreed to in writing, software 11 distributed under the License is distributed on an "AS IS" BASIS, 12 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 See the License for the specific language governing permissions and 14 limitations under the License. 15 */ 16 17 package containerd 18 19 import ( 20 "context" 21 "encoding/json" 22 "fmt" 23 "syscall" 24 25 "github.com/containerd/containerd/content" 26 "github.com/containerd/containerd/images" 27 v1 "github.com/opencontainers/image-spec/specs-go/v1" 28 ) 29 30 // StopSignalLabel is a well-known containerd label for storing the stop 31 // signal specified in the OCI image config 32 const StopSignalLabel = "io.containerd.image.config.stop-signal" 33 34 // GetStopSignal retrieves the container stop signal, specified by the 35 // well-known containerd label (StopSignalLabel) 36 func GetStopSignal(ctx context.Context, container Container, defaultSignal syscall.Signal) (syscall.Signal, error) { 37 labels, err := container.Labels(ctx) 38 if err != nil { 39 return -1, err 40 } 41 42 if stopSignal, ok := labels[StopSignalLabel]; ok { 43 return ParseSignal(stopSignal) 44 } 45 46 return defaultSignal, nil 47 } 48 49 // GetOCIStopSignal retrieves the stop signal specified in the OCI image config 50 func GetOCIStopSignal(ctx context.Context, image Image, defaultSignal string) (string, error) { 51 _, err := ParseSignal(defaultSignal) 52 if err != nil { 53 return "", err 54 } 55 ic, err := image.Config(ctx) 56 if err != nil { 57 return "", err 58 } 59 var ( 60 ociimage v1.Image 61 config v1.ImageConfig 62 ) 63 switch ic.MediaType { 64 case v1.MediaTypeImageConfig, images.MediaTypeDockerSchema2Config: 65 p, err := content.ReadBlob(ctx, image.ContentStore(), ic) 66 if err != nil { 67 return "", err 68 } 69 70 if err := json.Unmarshal(p, &ociimage); err != nil { 71 return "", err 72 } 73 config = ociimage.Config 74 default: 75 return "", fmt.Errorf("unknown image config media type %s", ic.MediaType) 76 } 77 78 if config.StopSignal == "" { 79 return defaultSignal, nil 80 } 81 82 return config.StopSignal, nil 83 }