128 lines
3.6 KiB
Go
128 lines
3.6 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package cmd
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import (
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"context"
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"encoding/json"
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"os"
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"syscall"
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"flag"
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"github.com/google/subcommands"
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"gvisor.googlesource.com/gvisor/runsc/boot"
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"gvisor.googlesource.com/gvisor/runsc/container"
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)
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const (
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unsetPID = -1
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)
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// Wait implements subcommands.Command for the "wait" command.
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type Wait struct {
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rootPID int
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pid int
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}
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// Name implements subcommands.Command.Name.
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func (*Wait) Name() string {
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return "wait"
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}
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// Synopsis implements subcommands.Command.Synopsis.
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func (*Wait) Synopsis() string {
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return "wait on a process inside a container"
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}
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// Usage implements subcommands.Command.Usage.
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func (*Wait) Usage() string {
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return `wait [flags] <container id>`
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}
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// SetFlags implements subcommands.Command.SetFlags.
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func (wt *Wait) SetFlags(f *flag.FlagSet) {
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f.IntVar(&wt.rootPID, "rootpid", unsetPID, "select a PID in the sandbox root PID namespace to wait on instead of the container's root process")
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f.IntVar(&wt.pid, "pid", unsetPID, "select a PID in the container's PID namespace to wait on instead of the container's root process")
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}
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// Execute implements subcommands.Command.Execute. It waits for a process in a
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// container to exit before returning.
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func (wt *Wait) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
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if f.NArg() != 1 {
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f.Usage()
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return subcommands.ExitUsageError
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}
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// You can't specify both -pid and -rootpid.
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if wt.rootPID != unsetPID && wt.pid != unsetPID {
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Fatalf("only one of -pid and -rootPid can be set")
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}
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id := f.Arg(0)
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conf := args[0].(*boot.Config)
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c, err := container.Load(conf.RootDir, id)
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if err != nil {
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Fatalf("loading container: %v", err)
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}
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var waitStatus syscall.WaitStatus
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switch {
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// Wait on the whole container.
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case wt.rootPID == unsetPID && wt.pid == unsetPID:
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ws, err := c.Wait()
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if err != nil {
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Fatalf("waiting on container %q: %v", c.ID, err)
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}
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waitStatus = ws
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// Wait on a PID in the root PID namespace.
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case wt.rootPID != unsetPID:
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ws, err := c.WaitRootPID(int32(wt.rootPID), true /* clearStatus */)
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if err != nil {
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Fatalf("waiting on PID in root PID namespace %d in container %q: %v", wt.rootPID, c.ID, err)
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}
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waitStatus = ws
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// Wait on a PID in the container's PID namespace.
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case wt.pid != unsetPID:
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ws, err := c.WaitPID(int32(wt.pid), true /* clearStatus */)
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if err != nil {
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Fatalf("waiting on PID %d in container %q: %v", wt.pid, c.ID, err)
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}
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waitStatus = ws
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}
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result := waitResult{
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ID: id,
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ExitStatus: exitStatus(waitStatus),
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}
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// Write json-encoded wait result directly to stdout.
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if err := json.NewEncoder(os.Stdout).Encode(result); err != nil {
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Fatalf("marshaling wait result: %v", err)
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}
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return subcommands.ExitSuccess
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}
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type waitResult struct {
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ID string `json:"id"`
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ExitStatus int `json:"exitStatus"`
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}
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// exitStatus returns the correct exit status for a process based on if it
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// was signaled or exited cleanly.
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func exitStatus(status syscall.WaitStatus) int {
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if status.Signaled() {
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return 128 + int(status.Signal())
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}
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return status.ExitStatus()
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}
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