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package dbus
import "net/url"
// EscapeBusAddressValue implements a requirement to escape the values
// in D-Bus server addresses, as defined by the D-Bus specification at
// https://dbus.freedesktop.org/doc/dbus-specification.html#addresses.
func EscapeBusAddressValue(val string) string {
toEsc := strNeedsEscape(val)
if toEsc == 0 {
// Avoid unneeded allocation/copying.
return val
}
// Avoid allocation for short paths.
var buf [64]byte
var out []byte
// Every to-be-escaped byte needs 2 extra bytes.
required := len(val) + 2*toEsc
if required <= len(buf) {
out = buf[:required]
} else {
out = make([]byte, required)
}
j := 0
for i := 0; i < len(val); i++ {
if ch := val[i]; needsEscape(ch) {
// Convert ch to %xx, where xx is hex value.
out[j] = '%'
out[j+1] = hexchar(ch >> 4)
out[j+2] = hexchar(ch & 0x0F)
j += 3
} else {
out[j] = ch
j++
}
}
return string(out)
}
// UnescapeBusAddressValue unescapes values in D-Bus server addresses,
// as defined by the D-Bus specification at
// https://dbus.freedesktop.org/doc/dbus-specification.html#addresses.
func UnescapeBusAddressValue(val string) (string, error) {
// Looks like url.PathUnescape does exactly what is required.
return url.PathUnescape(val)
}
// hexchar returns an octal representation of a n, where n < 16.
// For invalid values of n, the function panics.
func hexchar(n byte) byte {
const hex = "0123456789abcdef"
// For n >= len(hex), runtime will panic.
return hex[n]
}
// needsEscape tells if a byte is NOT one of optionally-escaped bytes.
func needsEscape(c byte) bool {
if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9' {
return false
}
switch c {
case '-', '_', '/', '\\', '.', '*':
return false
}
return true
}
// strNeedsEscape tells how many bytes in the string need escaping.
func strNeedsEscape(val string) int {
count := 0
for i := 0; i < len(val); i++ {
if needsEscape(val[i]) {
count++
}
}
return count
}
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