0b19f6cf5a
The std library now also supports the sha assembly instructions on ARM64. Thus, sha256-simd no longer provides a performance benefit.
123 lines
2.4 KiB
Go
123 lines
2.4 KiB
Go
package restic
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import (
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"crypto/rand"
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"io"
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)
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// Hash returns the ID for data.
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func Hash(data []byte) ID {
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return sha256.Sum256(data)
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}
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// idSize contains the size of an ID, in bytes.
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const idSize = sha256.Size
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// ID references content within a repository.
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type ID [idSize]byte
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// ParseID converts the given string to an ID.
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func ParseID(s string) (ID, error) {
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if len(s) != hex.EncodedLen(idSize) {
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return ID{}, fmt.Errorf("invalid length for ID: %q", s)
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}
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b, err := hex.DecodeString(s)
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if err != nil {
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return ID{}, fmt.Errorf("invalid ID: %s", err)
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}
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id := ID{}
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copy(id[:], b)
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return id, nil
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}
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func (id ID) String() string {
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return hex.EncodeToString(id[:])
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}
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// NewRandomID returns a randomly generated ID. When reading from rand fails,
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// the function panics.
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func NewRandomID() ID {
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id := ID{}
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_, err := io.ReadFull(rand.Reader, id[:])
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if err != nil {
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panic(err)
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}
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return id
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}
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const shortStr = 4
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// Str returns the shortened string version of id.
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func (id *ID) Str() string {
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if id == nil {
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return "[nil]"
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}
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if id.IsNull() {
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return "[null]"
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}
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return hex.EncodeToString(id[:shortStr])
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}
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// IsNull returns true iff id only consists of null bytes.
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func (id ID) IsNull() bool {
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var nullID ID
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return id == nullID
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}
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// Equal compares an ID to another other.
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func (id ID) Equal(other ID) bool {
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return id == other
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}
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// MarshalJSON returns the JSON encoding of id.
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func (id ID) MarshalJSON() ([]byte, error) {
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buf := make([]byte, 2+hex.EncodedLen(len(id)))
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buf[0] = '"'
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hex.Encode(buf[1:], id[:])
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buf[len(buf)-1] = '"'
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return buf, nil
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}
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// UnmarshalJSON parses the JSON-encoded data and stores the result in id.
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func (id *ID) UnmarshalJSON(b []byte) error {
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// check string length
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if len(b) != len(`""`)+hex.EncodedLen(idSize) {
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return fmt.Errorf("invalid length for ID: %q", b)
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}
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if b[0] != '"' {
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return fmt.Errorf("invalid start of string: %q", b[0])
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}
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// Strip JSON string delimiters. The json.Unmarshaler contract says we get
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// a valid JSON value, so we don't need to check that b[len(b)-1] == '"'.
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b = b[1 : len(b)-1]
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_, err := hex.Decode(id[:], b)
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if err != nil {
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return fmt.Errorf("invalid ID: %s", err)
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}
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return nil
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}
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// IDFromHash returns the ID for the hash.
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func IDFromHash(hash []byte) (id ID) {
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if len(hash) != idSize {
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panic("invalid hash type, not enough/too many bytes")
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}
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copy(id[:], hash)
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return id
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}
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