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// 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)
}
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