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