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| 1 | +// Copyright 2022 The Go Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style |
| 3 | +// license that can be found in the LICENSE file. |
| 4 | + |
| 5 | +// Code copied from |
| 6 | +// https://github.com/golang/go/blob/2ebe77a2fda1ee9ff6fd9a3e08933ad1ebaea039/src/cmd/go/internal/web/url.go |
| 7 | +// TODO(go.dev/issue/32456): if accepted, use the new API. |
| 8 | + |
| 9 | +package web |
| 10 | + |
| 11 | +import ( |
| 12 | + "errors" |
| 13 | + "net/url" |
| 14 | + "path/filepath" |
| 15 | + "runtime" |
| 16 | + "strings" |
| 17 | +) |
| 18 | + |
| 19 | +var errNotAbsolute = errors.New("path is not absolute") |
| 20 | + |
| 21 | +// URLToFilePath converts a file-scheme url to a file path. |
| 22 | +func URLToFilePath(u *url.URL) (string, error) { |
| 23 | + if u.Scheme != "file" { |
| 24 | + return "", errors.New("non-file URL") |
| 25 | + } |
| 26 | + |
| 27 | + checkAbs := func(path string) (string, error) { |
| 28 | + if !filepath.IsAbs(path) { |
| 29 | + return "", errNotAbsolute |
| 30 | + } |
| 31 | + return path, nil |
| 32 | + } |
| 33 | + |
| 34 | + if u.Path == "" { |
| 35 | + if u.Host != "" || u.Opaque == "" { |
| 36 | + return "", errors.New("file URL missing path") |
| 37 | + } |
| 38 | + return checkAbs(filepath.FromSlash(u.Opaque)) |
| 39 | + } |
| 40 | + |
| 41 | + path, err := convertFileURLPath(u.Host, u.Path) |
| 42 | + if err != nil { |
| 43 | + return path, err |
| 44 | + } |
| 45 | + return checkAbs(path) |
| 46 | +} |
| 47 | + |
| 48 | +// URLFromFilePath converts the given absolute path to a URL. |
| 49 | +func URLFromFilePath(path string) (*url.URL, error) { |
| 50 | + if !filepath.IsAbs(path) { |
| 51 | + return nil, errNotAbsolute |
| 52 | + } |
| 53 | + |
| 54 | + // If path has a Windows volume name, convert the volume to a host and prefix |
| 55 | + // per https://blogs.msdn.microsoft.com/ie/2006/12/06/file-uris-in-windows/. |
| 56 | + if vol := filepath.VolumeName(path); vol != "" { |
| 57 | + if strings.HasPrefix(vol, `\\`) { |
| 58 | + path = filepath.ToSlash(path[2:]) |
| 59 | + i := strings.IndexByte(path, '/') |
| 60 | + |
| 61 | + if i < 0 { |
| 62 | + // A degenerate case. |
| 63 | + // \\host.example.com (without a share name) |
| 64 | + // becomes |
| 65 | + // file://host.example.com/ |
| 66 | + return &url.URL{ |
| 67 | + Scheme: "file", |
| 68 | + Host: path, |
| 69 | + Path: "/", |
| 70 | + }, nil |
| 71 | + } |
| 72 | + |
| 73 | + // \\host.example.com\Share\path\to\file |
| 74 | + // becomes |
| 75 | + // file://host.example.com/Share/path/to/file |
| 76 | + return &url.URL{ |
| 77 | + Scheme: "file", |
| 78 | + Host: path[:i], |
| 79 | + Path: filepath.ToSlash(path[i:]), |
| 80 | + }, nil |
| 81 | + } |
| 82 | + |
| 83 | + // C:\path\to\file |
| 84 | + // becomes |
| 85 | + // file:///C:/path/to/file |
| 86 | + return &url.URL{ |
| 87 | + Scheme: "file", |
| 88 | + Path: "/" + filepath.ToSlash(path), |
| 89 | + }, nil |
| 90 | + } |
| 91 | + |
| 92 | + // /path/to/file |
| 93 | + // becomes |
| 94 | + // file:///path/to/file |
| 95 | + return &url.URL{ |
| 96 | + Scheme: "file", |
| 97 | + Path: filepath.ToSlash(path), |
| 98 | + }, nil |
| 99 | +} |
| 100 | + |
| 101 | +func convertFileURLPath(host, path string) (string, error) { |
| 102 | + if runtime.GOOS == "windows" { |
| 103 | + return convertFileURLPathWindows(host, path) |
| 104 | + } |
| 105 | + switch host { |
| 106 | + case "", "localhost": |
| 107 | + default: |
| 108 | + return "", errors.New("file URL specifies non-local host") |
| 109 | + } |
| 110 | + return filepath.FromSlash(path), nil |
| 111 | +} |
| 112 | + |
| 113 | +func convertFileURLPathWindows(host, path string) (string, error) { |
| 114 | + if len(path) == 0 || path[0] != '/' { |
| 115 | + return "", errNotAbsolute |
| 116 | + } |
| 117 | + |
| 118 | + path = filepath.FromSlash(path) |
| 119 | + |
| 120 | + // We interpret Windows file URLs per the description in |
| 121 | + // https://blogs.msdn.microsoft.com/ie/2006/12/06/file-uris-in-windows/. |
| 122 | + |
| 123 | + // The host part of a file URL (if any) is the UNC volume name, |
| 124 | + // but RFC 8089 reserves the authority "localhost" for the local machine. |
| 125 | + if host != "" && host != "localhost" { |
| 126 | + // A common "legacy" format omits the leading slash before a drive letter, |
| 127 | + // encoding the drive letter as the host instead of part of the path. |
| 128 | + // (See https://blogs.msdn.microsoft.com/freeassociations/2005/05/19/the-bizarre-and-unhappy-story-of-file-urls/.) |
| 129 | + // We do not support that format, but we should at least emit a more |
| 130 | + // helpful error message for it. |
| 131 | + if filepath.VolumeName(host) != "" { |
| 132 | + return "", errors.New("file URL encodes volume in host field: too few slashes?") |
| 133 | + } |
| 134 | + return `\\` + host + path, nil |
| 135 | + } |
| 136 | + |
| 137 | + // If host is empty, path must contain an initial slash followed by a |
| 138 | + // drive letter and path. Remove the slash and verify that the path is valid. |
| 139 | + if vol := filepath.VolumeName(path[1:]); vol == "" || strings.HasPrefix(vol, `\\`) { |
| 140 | + return "", errors.New("file URL missing drive letter") |
| 141 | + } |
| 142 | + return path[1:], nil |
| 143 | +} |
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