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