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package dbus
import (
"fmt"
"reflect"
"strings"
)
var sigToType = map[byte]reflect.Type{
'y': byteType,
'b': boolType,
'n': int16Type,
'q': uint16Type,
'i': int32Type,
'u': uint32Type,
'x': int64Type,
't': uint64Type,
'd': float64Type,
's': stringType,
'g': signatureType,
'o': objectPathType,
'v': variantType,
'h': unixFDIndexType,
}
// Signature represents a correct type signature as specified by the D-Bus
// specification. The zero value represents the empty signature, "".
type Signature struct {
str string
}
// SignatureOf returns the concatenation of all the signatures of the given
// values. It panics if one of them is not representable in D-Bus.
func SignatureOf(vs ...interface{}) Signature {
var s string
for _, v := range vs {
s += getSignature(reflect.TypeOf(v))
}
return Signature{s}
}
// SignatureOfType returns the signature of the given type. It panics if the
// type is not representable in D-Bus.
func SignatureOfType(t reflect.Type) Signature {
return Signature{getSignature(t)}
}
// getSignature returns the signature of the given type and panics on unknown types.
func getSignature(t reflect.Type) string {
// handle simple types first
switch t.Kind() {
case reflect.Uint8:
return "y"
case reflect.Bool:
return "b"
case reflect.Int16:
return "n"
case reflect.Uint16:
return "q"
case reflect.Int, reflect.Int32:
if t == unixFDType {
return "h"
}
return "i"
case reflect.Uint, reflect.Uint32:
if t == unixFDIndexType {
return "h"
}
return "u"
case reflect.Int64:
return "x"
case reflect.Uint64:
return "t"
case reflect.Float64:
return "d"
case reflect.Ptr:
return getSignature(t.Elem())
case reflect.String:
if t == objectPathType {
return "o"
}
return "s"
case reflect.Struct:
if t == variantType {
return "v"
} else if t == signatureType {
return "g"
}
var s string
for i := 0; i < t.NumField(); i++ {
field := t.Field(i)
if field.PkgPath == "" && field.Tag.Get("dbus") != "-" {
s += getSignature(t.Field(i).Type)
}
}
return "(" + s + ")"
case reflect.Array, reflect.Slice:
return "a" + getSignature(t.Elem())
case reflect.Map:
if !isKeyType(t.Key()) {
panic(InvalidTypeError{t})
}
return "a{" + getSignature(t.Key()) + getSignature(t.Elem()) + "}"
case reflect.Interface:
return "v"
}
panic(InvalidTypeError{t})
}
// ParseSignature returns the signature represented by this string, or a
// SignatureError if the string is not a valid signature.
func ParseSignature(s string) (sig Signature, err error) {
if len(s) == 0 {
return
}
if len(s) > 255 {
return Signature{""}, SignatureError{s, "too long"}
}
sig.str = s
for err == nil && len(s) != 0 {
err, s = validSingle(s, 0)
}
if err != nil {
sig = Signature{""}
}
return
}
// ParseSignatureMust behaves like ParseSignature, except that it panics if s
// is not valid.
func ParseSignatureMust(s string) Signature {
sig, err := ParseSignature(s)
if err != nil {
panic(err)
}
return sig
}
// Empty retruns whether the signature is the empty signature.
func (s Signature) Empty() bool {
return s.str == ""
}
// Single returns whether the signature represents a single, complete type.
func (s Signature) Single() bool {
err, r := validSingle(s.str, 0)
return err != nil && r == ""
}
// String returns the signature's string representation.
func (s Signature) String() string {
return s.str
}
// A SignatureError indicates that a signature passed to a function or received
// on a connection is not a valid signature.
type SignatureError struct {
Sig string
Reason string
}
func (e SignatureError) Error() string {
return fmt.Sprintf("dbus: invalid signature: %q (%s)", e.Sig, e.Reason)
}
// Try to read a single type from this string. If it was successful, err is nil
// and rem is the remaining unparsed part. Otherwise, err is a non-nil
// SignatureError and rem is "". depth is the current recursion depth which may
// not be greater than 64 and should be given as 0 on the first call.
func validSingle(s string, depth int) (err error, rem string) {
if s == "" {
return SignatureError{Sig: s, Reason: "empty signature"}, ""
}
if depth > 64 {
return SignatureError{Sig: s, Reason: "container nesting too deep"}, ""
}
switch s[0] {
case 'y', 'b', 'n', 'q', 'i', 'u', 'x', 't', 'd', 's', 'g', 'o', 'v', 'h':
return nil, s[1:]
case 'a':
if len(s) > 1 && s[1] == '{' {
i := findMatching(s[1:], '{', '}')
if i == -1 {
return SignatureError{Sig: s, Reason: "unmatched '{'"}, ""
}
i++
rem = s[i+1:]
s = s[2:i]
if err, _ = validSingle(s[:1], depth+1); err != nil {
return err, ""
}
err, nr := validSingle(s[1:], depth+1)
if err != nil {
return err, ""
}
if nr != "" {
return SignatureError{Sig: s, Reason: "too many types in dict"}, ""
}
return nil, rem
}
return validSingle(s[1:], depth+1)
case '(':
i := findMatching(s, '(', ')')
if i == -1 {
return SignatureError{Sig: s, Reason: "unmatched ')'"}, ""
}
rem = s[i+1:]
s = s[1:i]
for err == nil && s != "" {
err, s = validSingle(s, depth+1)
}
if err != nil {
rem = ""
}
return
}
return SignatureError{Sig: s, Reason: "invalid type character"}, ""
}
func findMatching(s string, left, right rune) int {
n := 0
for i, v := range s {
if v == left {
n++
} else if v == right {
n--
}
if n == 0 {
return i
}
}
return -1
}
// typeFor returns the type of the given signature. It ignores any left over
// characters and panics if s doesn't start with a valid type signature.
func typeFor(s string) (t reflect.Type) {
err, _ := validSingle(s, 0)
if err != nil {
panic(err)
}
if t, ok := sigToType[s[0]]; ok {
return t
}
switch s[0] {
case 'a':
if s[1] == '{' {
i := strings.LastIndex(s, "}")
t = reflect.MapOf(sigToType[s[2]], typeFor(s[3:i]))
} else {
t = reflect.SliceOf(typeFor(s[1:]))
}
case '(':
t = interfacesType
}
return
}
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