// Copyright 2018 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 cmd import ( "context" "fmt" "github.com/google/subcommands" "gvisor.dev/gvisor/runsc/flag" ) // NewHelp returns a help command for the given commander. func NewHelp(cdr *subcommands.Commander) *Help { return &Help{ cdr: cdr, } } // Help implements subcommands.Command for the "help" command. The 'help' // command prints help for commands registered to a Commander but also allows for // registering additional help commands that print other documentation. type Help struct { cdr *subcommands.Commander commands []subcommands.Command help bool } // Name implements subcommands.Command.Name. func (*Help) Name() string { return "help" } // Synopsis implements subcommands.Command.Synopsis. func (*Help) Synopsis() string { return "Print help documentation." } // Usage implements subcommands.Command.Usage. func (*Help) Usage() string { return `help [<subcommand>]: With an argument, prints detailed information on the use of the specified topic or subcommand. With no argument, print a list of all commands and a brief description of each. ` } // SetFlags implements subcommands.Command.SetFlags. func (h *Help) SetFlags(*flag.FlagSet) {} // Execute implements subcommands.Command.Execute. func (h *Help) Execute(ctx context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus { switch f.NArg() { case 0: fmt.Fprintf(h.cdr.Output, "Usage: %s <flags> <subcommand> <subcommand args>\n\n", h.cdr.Name()) fmt.Fprintf(h.cdr.Output, `runsc is the gVisor container runtime. Functionality is provided by subcommands. For help with a specific subcommand, use "%s %s <subcommand>". `, h.cdr.Name(), h.Name()) h.cdr.VisitGroups(func(g *subcommands.CommandGroup) { h.cdr.ExplainGroup(h.cdr.Output, g) }) fmt.Fprintf(h.cdr.Output, "Additional help topics (Use \"%s %s <topic>\" to see help on the topic):\n", h.cdr.Name(), h.Name()) for _, cmd := range h.commands { fmt.Fprintf(h.cdr.Output, "\t%-15s %s\n", cmd.Name(), cmd.Synopsis()) } fmt.Fprintf(h.cdr.Output, "\nUse \"%s flags\" for a list of top-level flags\n", h.cdr.Name()) return subcommands.ExitSuccess default: // Look for commands registered to the commander and print help explanation if found. found := false h.cdr.VisitCommands(func(g *subcommands.CommandGroup, cmd subcommands.Command) { if f.Arg(0) == cmd.Name() { h.cdr.ExplainCommand(h.cdr.Output, cmd) found = true } }) if found { return subcommands.ExitSuccess } // Next check commands registered to the help command. for _, cmd := range h.commands { if f.Arg(0) == cmd.Name() { fs := flag.NewFlagSet(f.Arg(0), flag.ContinueOnError) fs.Usage = func() { h.cdr.ExplainCommand(h.cdr.Error, cmd) } cmd.SetFlags(fs) if fs.Parse(f.Args()[1:]) != nil { return subcommands.ExitUsageError } return cmd.Execute(ctx, f, args...) } } fmt.Fprintf(h.cdr.Error, "Subcommand %s not understood\n", f.Arg(0)) } f.Usage() return subcommands.ExitUsageError } // Register registers a new help command. func (h *Help) Register(cmd subcommands.Command) { h.commands = append(h.commands, cmd) }