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// Copyright 2020 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package lfs
import (
"crypto/sha256"
"encoding/hex"
"errors"
"hash"
"io"
"os"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/storage"
)
var (
// ErrHashMismatch occurs if the content has does not match OID
ErrHashMismatch = errors.New("Content hash does not match OID")
// ErrSizeMismatch occurs if the content size does not match
ErrSizeMismatch = errors.New("Content size does not match")
)
// ContentStore provides a simple file system based storage.
type ContentStore struct {
storage.ObjectStorage
}
// NewContentStore creates the default ContentStore
func NewContentStore() *ContentStore {
contentStore := &ContentStore{ObjectStorage: storage.LFS}
return contentStore
}
// Get takes a Meta object and retrieves the content from the store, returning
// it as an io.ReadSeekCloser.
func (s *ContentStore) Get(pointer Pointer) (storage.Object, error) {
f, err := s.Open(pointer.RelativePath())
if err != nil {
log.Error("Whilst trying to read LFS OID[%s]: Unable to open Error: %v", pointer.Oid, err)
return nil, err
}
return f, err
}
// Put takes a Meta object and an io.Reader and writes the content to the store.
func (s *ContentStore) Put(pointer Pointer, r io.Reader) error {
p := pointer.RelativePath()
// Wrap the provided reader with an inline hashing and size checker
wrappedRd := newHashingReader(pointer.Size, pointer.Oid, r)
// now pass the wrapped reader to Save - if there is a size mismatch or hash mismatch then
// the errors returned by the newHashingReader should percolate up to here
written, err := s.Save(p, wrappedRd, pointer.Size)
if err != nil {
log.Error("Whilst putting LFS OID[%s]: Failed to copy to tmpPath: %s Error: %v", pointer.Oid, p, err)
return err
}
// This shouldn't happen but it is sensible to test
if written != pointer.Size {
if err := s.Delete(p); err != nil {
log.Error("Cleaning the LFS OID[%s] failed: %v", pointer.Oid, err)
}
return ErrSizeMismatch
}
return nil
}
// Exists returns true if the object exists in the content store.
func (s *ContentStore) Exists(pointer Pointer) (bool, error) {
_, err := s.ObjectStorage.Stat(pointer.RelativePath())
if err != nil {
if os.IsNotExist(err) {
return false, nil
}
return false, err
}
return true, nil
}
// Verify returns true if the object exists in the content store and size is correct.
func (s *ContentStore) Verify(pointer Pointer) (bool, error) {
p := pointer.RelativePath()
fi, err := s.ObjectStorage.Stat(p)
if os.IsNotExist(err) || (err == nil && fi.Size() != pointer.Size) {
return false, nil
} else if err != nil {
log.Error("Unable stat file: %s for LFS OID[%s] Error: %v", p, pointer.Oid, err)
return false, err
}
return true, nil
}
// ReadMetaObject will read a git_model.LFSMetaObject and return a reader
func ReadMetaObject(pointer Pointer) (io.ReadCloser, error) {
contentStore := NewContentStore()
return contentStore.Get(pointer)
}
type hashingReader struct {
internal io.Reader
currentSize int64
expectedSize int64
hash hash.Hash
expectedHash string
}
func (r *hashingReader) Read(b []byte) (int, error) {
n, err := r.internal.Read(b)
if n > 0 {
r.currentSize += int64(n)
wn, werr := r.hash.Write(b[:n])
if wn != n || werr != nil {
return n, werr
}
}
if err != nil && err == io.EOF {
if r.currentSize != r.expectedSize {
return n, ErrSizeMismatch
}
shaStr := hex.EncodeToString(r.hash.Sum(nil))
if shaStr != r.expectedHash {
return n, ErrHashMismatch
}
}
return n, err
}
func newHashingReader(expectedSize int64, expectedHash string, reader io.Reader) *hashingReader {
return &hashingReader{
internal: reader,
expectedSize: expectedSize,
expectedHash: expectedHash,
hash: sha256.New(),
}
}
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