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rlp: stricter rules for structs and pointers

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The rules have changed as follows:

* When decoding into pointers, empty values no longer produce
  a nil pointer. This can be overriden for struct fields using the
  struct tag "nil".
* When decoding into structs, the input list must contain an element
  for each field.
This commit is contained in:
Felix Lange
2015-04-17 01:16:46 +02:00
parent 1e2c93aa2d
commit cad64fb911
4 changed files with 148 additions and 52 deletions
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65
rlp/decode_test.go
View File

@ -280,7 +280,7 @@ type simplestruct struct {
type recstruct struct {
I uint
Child *recstruct
Child *recstruct `rlp:"nil"`
}
var (
@ -390,15 +390,33 @@ var decodeTests = []decodeTest{
{input: "8105", ptr: new(big.Int), error: "rlp: non-canonical size information for *big.Int"},
// structs
{input: "C0", ptr: new(simplestruct), value: simplestruct{0, ""}},
{input: "C105", ptr: new(simplestruct), value: simplestruct{5, ""}},
{input: "C50583343434", ptr: new(simplestruct), value: simplestruct{5, "444"}},
{
input: "C501C302C103",
input: "C50583343434",
ptr: new(simplestruct),
value: simplestruct{5, "444"},
},
{
input: "C601C402C203C0",
ptr: new(recstruct),
value: recstruct{1, &recstruct{2, &recstruct{3, nil}}},
},
// struct errors
{
input: "C0",
ptr: new(simplestruct),
error: "rlp: too few elements for rlp.simplestruct",
},
{
input: "C105",
ptr: new(simplestruct),
error: "rlp: too few elements for rlp.simplestruct",
},
{
input: "C7C50583343434C0",
ptr: new([]*simplestruct),
error: "rlp: too few elements for rlp.simplestruct, decoding into ([]*rlp.simplestruct)[1]",
},
{
input: "83222222",
ptr: new(simplestruct),
@ -417,19 +435,15 @@ var decodeTests = []decodeTest{
// pointers
{input: "00", ptr: new(*[]byte), value: &[]byte{0}},
{input: "80", ptr: new(*uint), value: (*uint)(nil)},
{input: "C0", ptr: new(*uint), value: (*uint)(nil)},
{input: "80", ptr: new(*uint), value: uintp(0)},
{input: "C0", ptr: new(*uint), error: "rlp: expected input string or byte for uint"},
{input: "07", ptr: new(*uint), value: uintp(7)},
{input: "8158", ptr: new(*uint), value: uintp(0x58)},
{input: "C109", ptr: new(*[]uint), value: &[]uint{9}},
{input: "C58403030303", ptr: new(*[][]byte), value: &[][]byte{{3, 3, 3, 3}}},
// check that input position is advanced also for empty values.
{input: "C3808005", ptr: new([]*uint), value: []*uint{nil, nil, uintp(5)}},
// pointer should be reset to nil
{input: "05", ptr: sharedPtr, value: uintp(5)},
{input: "80", ptr: sharedPtr, value: (*uint)(nil)},
{input: "C3808005", ptr: new([]*uint), value: []*uint{uintp(0), uintp(0), uintp(5)}},
// interface{}
{input: "00", ptr: new(interface{}), value: []byte{0}},
@ -599,6 +613,33 @@ func ExampleDecode() {
// Decoded value: rlp.example{A:0xa, B:0x14, private:0x0, String:"foobar"}
}
func ExampleDecode_structTagNil() {
// In this example, we'll use the "nil" struct tag to change
// how a pointer-typed field is decoded. The input contains an RLP
// list of one element, an empty string.
input := []byte{0xC1, 0x80}
// This type uses the normal rules.
// The empty input string is decoded as a pointer to an empty Go string.
var normalRules struct {
String *string
}
Decode(bytes.NewReader(input), &normalRules)
fmt.Printf("normal: String = %q\n", *normalRules.String)
// This type uses the struct tag.
// The empty input string is decoded as a nil pointer.
var withEmptyOK struct {
String *string `rlp:"nil"`
}
Decode(bytes.NewReader(input), &withEmptyOK)
fmt.Printf("with nil tag: String = %v\n", withEmptyOK.String)
// Output:
// normal: String = ""
// with nil tag: String = <nil>
}
func ExampleStream() {
input, _ := hex.DecodeString("C90A1486666F6F626172")
s := NewStream(bytes.NewReader(input), 0)