144 lines
3.9 KiB
Go
144 lines
3.9 KiB
Go
// Copyright 2022 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Code copied from
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// https://github.com/golang/go/blob/2ebe77a2fda1ee9ff6fd9a3e08933ad1ebaea039/src/cmd/go/internal/web/url.go
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// TODO(https://go.dev/issue/32456): if accepted, use the new API.
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package web
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import (
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"errors"
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"net/url"
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"path/filepath"
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"runtime"
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"strings"
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)
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var errNotAbsolute = errors.New("path is not absolute")
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// URLToFilePath converts a file-scheme url to a file path.
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func URLToFilePath(u *url.URL) (string, error) {
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if u.Scheme != "file" {
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return "", errors.New("non-file URL")
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}
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checkAbs := func(path string) (string, error) {
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if !filepath.IsAbs(path) {
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return "", errNotAbsolute
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}
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return path, nil
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}
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if u.Path == "" {
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if u.Host != "" || u.Opaque == "" {
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return "", errors.New("file URL missing path")
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}
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return checkAbs(filepath.FromSlash(u.Opaque))
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}
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path, err := convertFileURLPath(u.Host, u.Path)
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if err != nil {
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return path, err
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}
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return checkAbs(path)
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}
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// URLFromFilePath converts the given absolute path to a URL.
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func URLFromFilePath(path string) (*url.URL, error) {
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if !filepath.IsAbs(path) {
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return nil, errNotAbsolute
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}
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// If path has a Windows volume name, convert the volume to a host and prefix
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// per https://blogs.msdn.microsoft.com/ie/2006/12/06/file-uris-in-windows/.
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if vol := filepath.VolumeName(path); vol != "" {
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if strings.HasPrefix(vol, `\\`) {
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path = filepath.ToSlash(path[2:])
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i := strings.IndexByte(path, '/')
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if i < 0 {
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// A degenerate case.
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// \\host.example.com (without a share name)
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// becomes
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// file://host.example.com/
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return &url.URL{
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Scheme: "file",
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Host: path,
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Path: "/",
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}, nil
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}
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// \\host.example.com\Share\path\to\file
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// becomes
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// file://host.example.com/Share/path/to/file
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return &url.URL{
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Scheme: "file",
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Host: path[:i],
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Path: filepath.ToSlash(path[i:]),
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}, nil
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}
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// C:\path\to\file
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// becomes
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// file:///C:/path/to/file
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return &url.URL{
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Scheme: "file",
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Path: "/" + filepath.ToSlash(path),
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}, nil
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}
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// /path/to/file
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// becomes
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// file:///path/to/file
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return &url.URL{
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Scheme: "file",
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Path: filepath.ToSlash(path),
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}, nil
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}
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func convertFileURLPath(host, path string) (string, error) {
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if runtime.GOOS == "windows" {
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return convertFileURLPathWindows(host, path)
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}
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switch host {
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case "", "localhost":
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default:
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return "", errors.New("file URL specifies non-local host")
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}
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return filepath.FromSlash(path), nil
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}
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func convertFileURLPathWindows(host, path string) (string, error) {
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if len(path) == 0 || path[0] != '/' {
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return "", errNotAbsolute
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}
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path = filepath.FromSlash(path)
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// We interpret Windows file URLs per the description in
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// https://blogs.msdn.microsoft.com/ie/2006/12/06/file-uris-in-windows/.
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// The host part of a file URL (if any) is the UNC volume name,
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// but RFC 8089 reserves the authority "localhost" for the local machine.
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if host != "" && host != "localhost" {
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// A common "legacy" format omits the leading slash before a drive letter,
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// encoding the drive letter as the host instead of part of the path.
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// (See https://blogs.msdn.microsoft.com/freeassociations/2005/05/19/the-bizarre-and-unhappy-story-of-file-urls/.)
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// We do not support that format, but we should at least emit a more
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// helpful error message for it.
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if filepath.VolumeName(host) != "" {
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return "", errors.New("file URL encodes volume in host field: too few slashes?")
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}
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return `\\` + host + path, nil
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}
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// If host is empty, path must contain an initial slash followed by a
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// drive letter and path. Remove the slash and verify that the path is valid.
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if vol := filepath.VolumeName(path[1:]); vol == "" || strings.HasPrefix(vol, `\\`) {
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return "", errors.New("file URL missing drive letter")
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}
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return path[1:], nil
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}
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