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Vito Caputo
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unit: add systemd-escape unit name escaping/unescaping
Adds: UnitNameEscape(string) string UnitNameUnescape(string) string UnitNamePathEscape(string) string UnitNamePathUnescape(string) string *Escape are analogous to `systemd-escape` *Unescape are analogous to `systemd-escape --unescape` *Path* flavor is analogous to `systemd-escape --path [--unescape]`
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‎unit/escape.go‎

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// Copyright 2015 CoreOS, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Implements systemd-escape [--unescape] [--path]
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package unit
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import (
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"fmt"
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"strconv"
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"strings"
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)
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const (
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allowed = `:_.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789`
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)
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// If isPath is true:
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// We remove redundant '/'s, the leading '/', and trailing '/'.
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// If the result is empty, a '/' is inserted.
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//
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// We always:
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// Replace the following characters with `\x%x`:
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// Leading `.`
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// `-`, `\`, and anything not in this set: `:-_.\[0-9a-zA-Z]`
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// Replace '/' with '-'.
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func escape(unescaped string, isPath bool) string {
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e := []byte{}
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inSlashes := false
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start := true
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for i := 0; i < len(unescaped); i++ {
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c := unescaped[i]
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if isPath {
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if c == '/' {
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inSlashes = true
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continue
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} else if inSlashes {
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inSlashes = false
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if !start {
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e = append(e, '-')
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}
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}
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}
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if c == '/' {
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e = append(e, '-')
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} else if start && c == '.' || strings.IndexByte(allowed, c) == -1 {
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e = append(e, []byte(fmt.Sprintf(`\x%x`, c))...)
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} else {
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e = append(e, c)
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}
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start = false
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}
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if isPath && len(e) == 0 {
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e = append(e, '-')
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}
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return string(e)
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}
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// If isPath is true:
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// We always return a string beginning with '/'.
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//
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// We always:
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// Replace '-' with '/'.
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// Replace `\x%x` with the value represented in hex.
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func unescape(escaped string, isPath bool) string {
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u := []byte{}
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for i := 0; i < len(escaped); i++ {
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c := escaped[i]
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if c == '-' {
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c = '/'
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} else if c == '\\' && len(escaped)-i >= 4 && escaped[i+1] == 'x' {
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n, err := strconv.ParseInt(escaped[i+2:i+4], 16, 8)
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if err == nil {
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c = byte(n)
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i += 3
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}
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}
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u = append(u, c)
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}
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if isPath && (len(u) == 0 || u[0] != '/') {
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u = append([]byte("/"), u...)
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}
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return string(u)
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}
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// UnitNameEscape escapes a string as `systemd-escape` would
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func UnitNameEscape(unescaped string) string {
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return escape(unescaped, false)
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}
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// UnitNameUnescape unescapes a string as `systemd-escape --unescape` would
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func UnitNameUnescape(escaped string) string {
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return unescape(escaped, false)
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}
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// UnitNamePathEscape escapes a string as `systemd-escape --path` would
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func UnitNamePathEscape(unescaped string) string {
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return escape(unescaped, true)
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}
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// UnitNamePathUnescape unescapes a string as `systemd-escape --path --unescape` would
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func UnitNamePathUnescape(escaped string) string {
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return unescape(escaped, true)
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}

‎unit/escape_test.go‎

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// Copyright 2015 CoreOS, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package unit
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import (
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"testing"
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)
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func TestUnitNameEscape(t *testing.T) {
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tests := []struct {
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in string
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out string
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isPath bool
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}{
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// turn empty string path into escaped /
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{
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in: "",
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out: "-",
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isPath: true,
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},
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// turn redundant ////s into single escaped /
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{
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in: "/////////",
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out: "-",
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isPath: true,
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},
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// remove all redundant ////s
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{
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in: "///foo////bar/////tail//////",
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out: "foo-bar-tail",
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isPath: true,
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},
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// leave empty string empty
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{
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in: "",
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out: "",
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isPath: false,
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},
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// escape leading dot
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{
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in: ".",
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out: `\x2e`,
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isPath: true,
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},
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// escape leading dot
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{
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in: "/.",
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out: `\x2e`,
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isPath: true,
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},
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// escape leading dot
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{
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in: "/////////.",
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out: `\x2e`,
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isPath: true,
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},
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// escape leading dot
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{
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in: "/////////.///////////////",
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out: `\x2e`,
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isPath: true,
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},
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// escape leading dot
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{
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in: ".....",
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out: `\x2e....`,
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isPath: true,
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},
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// escape leading dot
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{
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in: "/.foo/.bar",
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out: `\x2efoo-.bar`,
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isPath: true,
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},
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// escape leading dot
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{
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in: ".foo/.bar",
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out: `\x2efoo-.bar`,
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isPath: true,
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},
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// escape leading dot
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{
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in: ".foo/.bar",
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out: `\x2efoo-.bar`,
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isPath: false,
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},
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// escape disallowed
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{
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in: `///..\-!#??///`,
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out: `---..\x5c\x2d\x21\x23\x3f\x3f---`,
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isPath: false,
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},
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// escape disallowed
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{
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in: `///..\-!#??///`,
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out: `\x2e.\x5c\x2d\x21\x23\x3f\x3f`,
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isPath: true,
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},
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// escape real-world example
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{
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in: `user-cloudinit@/var/lib/coreos/vagrant/vagrantfile-user-data.service`,
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out: `user\x2dcloudinit\x40-var-lib-coreos-vagrant-vagrantfile\x2duser\x2ddata.service`,
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isPath: false,
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},
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}
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for i, tt := range tests {
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var s string
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if tt.isPath {
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s = UnitNamePathEscape(tt.in)
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} else {
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s = UnitNameEscape(tt.in)
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}
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if s != tt.out {
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t.Errorf("case %d: failed escaping %v isPath: %v - expected %v, got %v", i, tt.in, tt.isPath, tt.out, s)
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}
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}
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}
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func TestUnitNameUnescape(t *testing.T) {
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tests := []struct {
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in string
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out string
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isPath bool
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}{
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// turn empty string path into /
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{
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in: "",
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out: "/",
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isPath: true,
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},
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// leave empty string empty
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{
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in: "",
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out: "",
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isPath: false,
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},
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// turn ////s into
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{
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in: "---------",
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out: "/////////",
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isPath: true,
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},
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// unescape hex
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{
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in: `---..\x5c\x2d\x21\x23\x3f\x3f---`,
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out: `///..\-!#??///`,
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isPath: false,
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},
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// unescape hex
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{
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in: `\x2e.\x5c\x2d\x21\x23\x3f\x3f`,
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out: `/..\-!#??`,
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isPath: true,
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},
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// unescape hex, retain invalids
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{
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in: `\x2e.\x5c\x2d\xaZ\x.o\x21\x23\x3f\x3f`,
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out: `/..\-\xaZ\x.o!#??`,
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isPath: true,
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},
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// unescape hex, retain invalids, partial tail
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{
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in: `\x2e.\x5c\x\x2d\xaZ\x.o\x21\x23\x3f\x3f\x3`,
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out: `/..\\x-\xaZ\x.o!#??\x3`,
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isPath: true,
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},
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// unescape hex, retain invalids, partial tail
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{
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in: `\x2e.\x5c\x\x2d\xaZ\x.o\x21\x23\x3f\x3f\x`,
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out: `/..\\x-\xaZ\x.o!#??\x`,
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isPath: true,
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},
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// unescape hex, retain invalids, partial tail
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{
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in: `\x2e.\x5c\x\x2d\xaZ\x.o\x21\x23\x3f\x3f\`,
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out: `/..\\x-\xaZ\x.o!#??\`,
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isPath: true,
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},
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// unescape real-world example
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{
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in: `user\x2dcloudinit\x40-var-lib-coreos-vagrant-vagrantfile\x2duser\x2ddata.service`,
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out: `user-cloudinit@/var/lib/coreos/vagrant/vagrantfile-user-data.service`,
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isPath: false,
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},
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}
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for i, tt := range tests {
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var s string
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if tt.isPath {
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s = UnitNamePathUnescape(tt.in)
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} else {
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s = UnitNameUnescape(tt.in)
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}
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if s != tt.out {
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t.Errorf("case %d: failed unescaping %v isPath: %v - expected %v, got %v", i, tt.in, tt.isPath, tt.out, s)
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}
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}
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}

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