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restic/internal/restic/id.go
greatroar d03460010f internal/restic: Fix ID.UnmarshalJSON, ParseID
ID.UnmarshalJSON accepted non-JSON input with ' as the string delimiter.
Also, the error message for non-hex input was less informative than it
could be and it performed too many checks.

Changed ParseID to keep the error messages consistent.
2022-10-16 10:39:52 +02:00

125 lines
2.4 KiB
Go

package restic
import (
"crypto/rand"
"encoding/hex"
"fmt"
"io"
"github.com/minio/sha256-simd"
)
// Hash returns the ID for data.
func Hash(data []byte) ID {
return sha256.Sum256(data)
}
// idSize contains the size of an ID, in bytes.
const idSize = sha256.Size
// ID references content within a repository.
type ID [idSize]byte
// ParseID converts the given string to an ID.
func ParseID(s string) (ID, error) {
if len(s) != hex.EncodedLen(idSize) {
return ID{}, fmt.Errorf("invalid length for ID: %q", s)
}
b, err := hex.DecodeString(s)
if err != nil {
return ID{}, fmt.Errorf("invalid ID: %s", err)
}
id := ID{}
copy(id[:], b)
return id, nil
}
func (id ID) String() string {
return hex.EncodeToString(id[:])
}
// NewRandomID returns a randomly generated ID. When reading from rand fails,
// the function panics.
func NewRandomID() ID {
id := ID{}
_, err := io.ReadFull(rand.Reader, id[:])
if err != nil {
panic(err)
}
return id
}
const shortStr = 4
// Str returns the shortened string version of id.
func (id *ID) Str() string {
if id == nil {
return "[nil]"
}
if id.IsNull() {
return "[null]"
}
return hex.EncodeToString(id[:shortStr])
}
// IsNull returns true iff id only consists of null bytes.
func (id ID) IsNull() bool {
var nullID ID
return id == nullID
}
// Equal compares an ID to another other.
func (id ID) Equal(other ID) bool {
return id == other
}
// MarshalJSON returns the JSON encoding of id.
func (id ID) MarshalJSON() ([]byte, error) {
buf := make([]byte, 2+hex.EncodedLen(len(id)))
buf[0] = '"'
hex.Encode(buf[1:], id[:])
buf[len(buf)-1] = '"'
return buf, nil
}
// UnmarshalJSON parses the JSON-encoded data and stores the result in id.
func (id *ID) UnmarshalJSON(b []byte) error {
// check string length
if len(b) != len(`""`)+hex.EncodedLen(idSize) {
return fmt.Errorf("invalid length for ID: %q", b)
}
if b[0] != '"' {
return fmt.Errorf("invalid start of string: %q", b[0])
}
// Strip JSON string delimiters. The json.Unmarshaler contract says we get
// a valid JSON value, so we don't need to check that b[len(b)-1] == '"'.
b = b[1 : len(b)-1]
_, err := hex.Decode(id[:], b)
if err != nil {
return fmt.Errorf("invalid ID: %s", err)
}
return nil
}
// IDFromHash returns the ID for the hash.
func IDFromHash(hash []byte) (id ID) {
if len(hash) != idSize {
panic("invalid hash type, not enough/too many bytes")
}
copy(id[:], hash)
return id
}