// Copyright 2023 The Gitea Authors. All rights reserved.// SPDX-License-Identifier: MIT package git import (	"crypto/sha1"	"crypto/sha256"	"regexp"	"strconv") // sha1Pattern can be used to determine if a string is an valid shavar sha1Pattern = regexp.MustCompile(`^[0-9a-f]{4,40}$`) // sha256Pattern can be used to determine if a string is an valid shavar sha256Pattern = regexp.MustCompile(`^[0-9a-f]{4,64}$`) type ObjectFormat interface {	// Name returns the name of the object format	Name() string	// EmptyObjectID creates a new empty ObjectID from an object format hash name	EmptyObjectID() ObjectID	// EmptyTree is the hash of an empty tree	EmptyTree() ObjectID	// FullLength is the length of the hash's hex string	FullLength() int	// IsValid returns true if the input is a valid hash	IsValid(input string) bool	// MustID creates a new ObjectID from a byte slice	MustID(b []byte) ObjectID	// ComputeHash compute the hash for a given ObjectType and content	ComputeHash(t ObjectType, content []byte) ObjectID} /* SHA1 Type */type Sha1ObjectFormatImpl struct{} var (	emptySha1ObjectID = &Sha1Hash{}	emptySha1Tree     = &Sha1Hash{		0x4b, 0x82, 0x5d, 0xc6, 0x42, 0xcb, 0x6e, 0xb9, 0xa0, 0x60,		0xe5, 0x4b, 0xf8, 0xd6, 0x92, 0x88, 0xfb, 0xee, 0x49, 0x04,	}) func (Sha1ObjectFormatImpl) Name() string { return "sha1" }func (Sha1ObjectFormatImpl) EmptyObjectID() ObjectID {	return emptySha1ObjectID} func (Sha1ObjectFormatImpl) EmptyTree() ObjectID {	return emptySha1Tree}func (Sha1ObjectFormatImpl) FullLength() int { return 40 }func (Sha1ObjectFormatImpl) IsValid(input string) bool {	return sha1Pattern.MatchString(input)} func (Sha1ObjectFormatImpl) MustID(b []byte) ObjectID {	var id Sha1Hash	copy(id[0:20], b)	return &id} // ComputeHash compute the hash for a given ObjectType and contentfunc (h Sha1ObjectFormatImpl) ComputeHash(t ObjectType, content []byte) ObjectID {	hasher := sha1.New()	_, _ = hasher.Write(t.Bytes())	_, _ = hasher.Write([]byte(" "))	_, _ = hasher.Write([]byte(strconv.FormatInt(int64(len(content)), 10)))	_, _ = hasher.Write([]byte{0}) 	// HashSum generates a SHA1 for the provided hash	var sha1 Sha1Hash	copy(sha1[:], hasher.Sum(nil))	return &sha1} /* SHA256 Type */type Sha256ObjectFormatImpl struct{} var (	emptySha256ObjectID = &Sha256Hash{}	emptySha256Tree     = &Sha256Hash{		0x6e, 0xf1, 0x9b, 0x41, 0x22, 0x5c, 0x53, 0x69, 0xf1, 0xc1,		0x04, 0xd4, 0x5d, 0x8d, 0x85, 0xef, 0xa9, 0xb0, 0x57, 0xb5,		0x3b, 0x14, 0xb4, 0xb9, 0xb9, 0x39, 0xdd, 0x74, 0xde, 0xcc,		0x53, 0x21,	}) func (Sha256ObjectFormatImpl) Name() string { return "sha256" }func (Sha256ObjectFormatImpl) EmptyObjectID() ObjectID {	return emptySha256ObjectID} func (Sha256ObjectFormatImpl) EmptyTree() ObjectID {	return emptySha256Tree}func (Sha256ObjectFormatImpl) FullLength() int { return 64 }func (Sha256ObjectFormatImpl) IsValid(input string) bool {	return sha256Pattern.MatchString(input)} func (Sha256ObjectFormatImpl) MustID(b []byte) ObjectID {	var id Sha256Hash	copy(id[0:32], b)	return &id} // ComputeHash compute the hash for a given ObjectType and contentfunc (h Sha256ObjectFormatImpl) ComputeHash(t ObjectType, content []byte) ObjectID {	hasher := sha256.New()	_, _ = hasher.Write(t.Bytes())	_, _ = hasher.Write([]byte(" "))	_, _ = hasher.Write([]byte(strconv.FormatInt(int64(len(content)), 10)))	_, _ = hasher.Write([]byte{0}) 	// HashSum generates a SHA256 for the provided hash	var sha256 Sha1Hash	copy(sha256[:], hasher.Sum(nil))	return &sha256} var (	Sha1ObjectFormat   ObjectFormat = Sha1ObjectFormatImpl{}	Sha256ObjectFormat ObjectFormat = Sha256ObjectFormatImpl{}) var SupportedObjectFormats = []ObjectFormat{	Sha1ObjectFormat,} func ObjectFormatFromName(name string) ObjectFormat {	for _, objectFormat := range SupportedObjectFormats {		if name == objectFormat.Name() {			return objectFormat		}	}	return nil} func IsValidObjectFormat(name string) bool {	return ObjectFormatFromName(name) != nil}