github.com/gitbundle/modules@v0.0.0-20231025071548-85b91c5c3b01/git/sha1_nogogit.go (about)

     1  // Copyright 2023 The GitBundle Inc. All rights reserved.
     2  // Copyright 2017 The Gitea Authors. All rights reserved.
     3  // Use of this source code is governed by a MIT-style
     4  // license that can be found in the LICENSE file.
     5  
     6  // Copyright 2015 The Gogs Authors. All rights reserved.
     7  
     8  //go:build !gogit
     9  
    10  package git
    11  
    12  import (
    13  	"crypto/sha1"
    14  	"encoding/hex"
    15  	"hash"
    16  	"strconv"
    17  )
    18  
    19  // SHA1 a git commit name
    20  type SHA1 [20]byte
    21  
    22  // String returns a string representation of the SHA
    23  func (s SHA1) String() string {
    24  	return hex.EncodeToString(s[:])
    25  }
    26  
    27  // IsZero returns whether this SHA1 is all zeroes
    28  func (s SHA1) IsZero() bool {
    29  	var empty SHA1
    30  	return s == empty
    31  }
    32  
    33  // ComputeBlobHash compute the hash for a given blob content
    34  func ComputeBlobHash(content []byte) SHA1 {
    35  	return ComputeHash(ObjectBlob, content)
    36  }
    37  
    38  // ComputeHash compute the hash for a given ObjectType and content
    39  func ComputeHash(t ObjectType, content []byte) SHA1 {
    40  	h := NewHasher(t, int64(len(content)))
    41  	_, _ = h.Write(content)
    42  	return h.Sum()
    43  }
    44  
    45  // Hasher is a struct that will generate a SHA1
    46  type Hasher struct {
    47  	hash.Hash
    48  }
    49  
    50  // NewHasher takes an object type and size and creates a hasher to generate a SHA
    51  func NewHasher(t ObjectType, size int64) Hasher {
    52  	h := Hasher{sha1.New()}
    53  	_, _ = h.Write(t.Bytes())
    54  	_, _ = h.Write([]byte(" "))
    55  	_, _ = h.Write([]byte(strconv.FormatInt(size, 10)))
    56  	_, _ = h.Write([]byte{0})
    57  	return h
    58  }
    59  
    60  // Sum generates a SHA1 for the provided hash
    61  func (h Hasher) Sum() (sha1 SHA1) {
    62  	copy(sha1[:], h.Hash.Sum(nil))
    63  	return
    64  }