/cmd/xs/main.go
Go | 212 lines | 160 code | 34 blank | 18 comment | 26 complexity | 0d10225472fd3d83d745ed05e65e8d7a MD5 | raw file
- package main
- import (
- "flag"
- "fmt"
- "io"
- "log"
- "os"
- "strings"
- "sync"
- "text/template"
- "unicode"
- "unicode/utf8"
- )
- // A Command is an implementation of a xs command
- // like xs read or xs write.
- type Command struct {
- // Run runs the command.
- // The args are the arguments after the command name.
- Run func(cmd *Command, args []string)
- // UsageLine is the one-line usage message.
- // The first word in the line is taken to be the command name.
- UsageLine string
- // Short is the short description shown in the 'xs help' output.
- Short string
- // Long is the long message shown in the 'xs help <this-command>' output.
- Long string
- // Flag is a set of flags specific to this command.
- Flag flag.FlagSet
- // CustomFlags indicates that the command will do its own
- // flag parsing.
- CustomFlags bool
- }
- // Name returns the command's name: the first word in the usage line.
- func (c *Command) Name() string {
- name := c.UsageLine
- i := strings.Index(name, " ")
- if i >= 0 {
- name = name[:i]
- }
- return name
- }
- func (c *Command) Usage() {
- fmt.Fprintf(os.Stderr, "usage: %s\n\n", c.UsageLine)
- fmt.Fprintf(os.Stderr, "%s\n", strings.TrimSpace(c.Long))
- os.Exit(2)
- }
- // Commands lists the available commands and help topics.
- // The order here is the order in which they are printed by 'yapm help'.
- var commands = []*Command{
- cmdRead,
- cmdWrite,
- cmdWatch,
- }
- var exitStatus = 0
- var exitMu sync.Mutex
- func setExitStatus(n int) {
- exitMu.Lock()
- if exitStatus < n {
- exitStatus = n
- }
- exitMu.Unlock()
- }
- func main() {
- flag.Usage = usage
- flag.Parse()
- log.SetFlags(0)
- args := flag.Args()
- if len(args) < 1 {
- usage()
- }
- if args[0] == "help" {
- help(args[1:])
- return
- }
- for _, cmd := range commands {
- if cmd.Name() == args[0] && cmd.Run != nil {
- cmd.Flag.Usage = func() { cmd.Usage() }
- if cmd.CustomFlags {
- args = args[1:]
- } else {
- cmd.Flag.Parse(args[1:])
- args = cmd.Flag.Args()
- }
- cmd.Run(cmd, args)
- exit()
- return
- }
- }
- fmt.Fprintf(os.Stderr, "xs: unknown subcommand %q\nRun 'xs help' for usage.\n", args[0])
- setExitStatus(2)
- exit()
- }
- var usageTemplate = `xs is a tool for comunication with xenstore.
- Usage:
- xs command [arguments]
- The commands are:
- {{range .}}
- {{.Name | printf "%-11s"}} {{.Short}}{{end}}
- Use "xs help [command]" for more information about a command.
- `
- var helpTemplate = `usage: xs {{.UsageLine}}
- {{.Long | trim}}
- `
- // tmpl executes the given template text on data, writing the result to w.
- func tmpl(w io.Writer, text string, data interface{}) {
- t := template.New("top")
- t.Funcs(template.FuncMap{"trim": strings.TrimSpace, "capitalize": capitalize})
- template.Must(t.Parse(text))
- if err := t.Execute(w, data); err != nil {
- panic(err)
- }
- }
- func capitalize(s string) string {
- if s == "" {
- return s
- }
- r, n := utf8.DecodeRuneInString(s)
- return string(unicode.ToTitle(r)) + s[n:]
- }
- func printUsage(w io.Writer) {
- tmpl(w, usageTemplate, commands)
- }
- func usage() {
- printUsage(os.Stderr)
- os.Exit(2)
- }
- // help implements the 'help' command.
- func help(args []string) {
- if len(args) == 0 {
- printUsage(os.Stdout)
- // not exit 2: succeeded at 'go help'.
- return
- }
- if len(args) != 1 {
- fmt.Fprintf(os.Stderr, "usage: xs help command\n\nToo many arguments given.\n")
- os.Exit(2) // failed at 'xs help'
- }
- arg := args[0]
- for _, cmd := range commands {
- if cmd.Name() == arg {
- tmpl(os.Stdout, helpTemplate, cmd)
- // not exit 2: succeeded at 'go help cmd'.
- return
- }
- }
- fmt.Fprintf(os.Stderr, "Unknown help topic %#q. Run 'xs help'.\n", arg)
- os.Exit(2) // failed at 'go help cmd'
- }
- var atexitFuncs []func()
- func atexit(f func()) {
- atexitFuncs = append(atexitFuncs, f)
- }
- func exit() {
- for _, f := range atexitFuncs {
- f()
- }
- os.Exit(exitStatus)
- }
- func fatalf(format string, args ...interface{}) {
- errorf(format, args...)
- exit()
- }
- func errorf(format string, args ...interface{}) {
- log.Printf(format, args...)
- setExitStatus(1)
- }
- var logf = log.Printf
- func exitIfErrors() {
- if exitStatus != 0 {
- exit()
- }
- }