webbrowser.go

/* This code is from https://github.com/toqueteos/webbrowser and is licensed under the MIT license:

The MIT License (MIT) Copyright (c) 2013-15 by Carlos Cobo and contributors.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

package main

import (
	"errors"
	"fmt"
	"net/url"
	"os"
	"os/exec"
	"runtime"
	"strings"
)

func init() {
	// Register a generic browser, if any, for current OS.
	if os, ok := osCommand[runtime.GOOS]; ok {
		Candidates = append(Candidates, GenericBrowser{os.cmd, os.args})
	}
}

type args struct {
	cmd  string
	args []string
}

var (
	osCommand = map[string]*args{
		"darwin":  &args{"open", nil},
		"freebsd": &args{"xdg-open", nil},
		"linux":   &args{"xdg-open", nil},
		"netbsd":  &args{"xdg-open", nil},
		"openbsd": &args{"xdg-open", nil}, // It may be open instead
		"windows": &args{"cmd", []string{"/c", "start"}},
	}
	ErrCantOpen     = errors.New("webbrowser.Open: can't open webpage")
	ErrNoCandidates = errors.New("webbrowser.Open: no browser candidate found for your OS.")
)

// List of registered `Browser`s that will be tried with Open.
var Candidates []Browser

type Browser interface {
	Open(string) error
}

// GenericBrowser just holds a command name and its arguments; the url will be
// appended as last arg. If you need to use string replacement for url define
// your own implementation.
type GenericBrowser struct {
	Cmd  string
	Args []string
}

func (gb GenericBrowser) Open(s string) error {
	u, err := url.Parse(s)
	if err != nil {
		return err
	}

	// Enforce a scheme (windows requires scheme to be set to work properly).
	if u.Scheme != "https" {
		u.Scheme = "http"
	}
	s = u.String()

	// Escape characters not allowed by cmd/bash
	switch runtime.GOOS {
	case "windows":
		s = strings.Replace(s, "&", `^&`, -1)
	}

	var cmd *exec.Cmd
	if gb.Args != nil {
		cmd = exec.Command(gb.Cmd, append(gb.Args, s)...)
	} else {
		cmd = exec.Command(gb.Cmd, s)
	}
	return cmd.Run()
}

// Open opens an URL on the first available candidate found.
func Open(s string) error {
	if len(Candidates) == 0 {
		return ErrNoCandidates
	}

	for _, b := range Candidates {
		err := b.Open(s)
		if err == nil {
			return nil
		}
	}

	// Try to determine if there's a display available (only linux) and we
	// aren't on a terminal (all but windows).
	switch runtime.GOOS {
	case "linux":
		// No display, no need to open a browser. Lynx users **MAY** have
		// something to say about this.
		if os.Getenv("DISPLAY") == "" {
			return fmt.Errorf("Tried to open %q on default webbrowser, no screen found.\n", s)
		}
		fallthrough
	case "darwin":
		// Check SSH env vars.
		if os.Getenv("SSH_CLIENT") != "" || os.Getenv("SSH_TTY") != "" {
			return fmt.Errorf("Tried to open %q on default webbrowser, but you are running a shell session.\n", s)
		}
	}

	return ErrCantOpen
}