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Continuing on from #14888 The previous implementation has race whereby an incomplete upload or hash mismatch upload can end up in the ContentStore. This PR moves the validation into the reader so that if there is a hash error or size mismatch the reader will return with an error instead of an io.EOF causing the storage to abort the storage. Signed-off-by: Andrew Thornton <art27@cantab.net>
161 lines
4.2 KiB
Go
161 lines
4.2 KiB
Go
// Copyright 2020 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package lfs
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import (
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"fmt"
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"hash"
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"io"
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"os"
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"code.gitea.io/gitea/models"
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"code.gitea.io/gitea/modules/log"
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"code.gitea.io/gitea/modules/storage"
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)
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var (
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errHashMismatch = errors.New("Content hash does not match OID")
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errSizeMismatch = errors.New("Content size does not match")
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)
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// ErrRangeNotSatisfiable represents an error which request range is not satisfiable.
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type ErrRangeNotSatisfiable struct {
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FromByte int64
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}
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func (err ErrRangeNotSatisfiable) Error() string {
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return fmt.Sprintf("Requested range %d is not satisfiable", err.FromByte)
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}
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// IsErrRangeNotSatisfiable returns true if the error is an ErrRangeNotSatisfiable
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func IsErrRangeNotSatisfiable(err error) bool {
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_, ok := err.(ErrRangeNotSatisfiable)
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return ok
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}
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// ContentStore provides a simple file system based storage.
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type ContentStore struct {
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storage.ObjectStorage
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}
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// Get takes a Meta object and retrieves the content from the store, returning
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// it as an io.Reader. If fromByte > 0, the reader starts from that byte
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func (s *ContentStore) Get(meta *models.LFSMetaObject, fromByte int64) (io.ReadCloser, error) {
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f, err := s.Open(meta.RelativePath())
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if err != nil {
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log.Error("Whilst trying to read LFS OID[%s]: Unable to open Error: %v", meta.Oid, err)
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return nil, err
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}
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if fromByte > 0 {
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if fromByte >= meta.Size {
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return nil, ErrRangeNotSatisfiable{
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FromByte: fromByte,
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}
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}
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_, err = f.Seek(fromByte, io.SeekStart)
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if err != nil {
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log.Error("Whilst trying to read LFS OID[%s]: Unable to seek to %d Error: %v", meta.Oid, fromByte, err)
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}
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}
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return f, err
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}
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// Put takes a Meta object and an io.Reader and writes the content to the store.
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func (s *ContentStore) Put(meta *models.LFSMetaObject, r io.Reader) error {
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p := meta.RelativePath()
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// Wrap the provided reader with an inline hashing and size checker
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wrappedRd := newHashingReader(meta.Size, meta.Oid, r)
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// now pass the wrapped reader to Save - if there is a size mismatch or hash mismatch then
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// the errors returned by the newHashingReader should percolate up to here
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written, err := s.Save(p, wrappedRd)
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if err != nil {
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log.Error("Whilst putting LFS OID[%s]: Failed to copy to tmpPath: %s Error: %v", meta.Oid, p, err)
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return err
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}
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// This shouldn't happen but it is sensible to test
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if written != meta.Size {
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if err := s.Delete(p); err != nil {
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log.Error("Cleaning the LFS OID[%s] failed: %v", meta.Oid, err)
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}
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return errSizeMismatch
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}
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return nil
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}
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// Exists returns true if the object exists in the content store.
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func (s *ContentStore) Exists(meta *models.LFSMetaObject) (bool, error) {
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_, err := s.ObjectStorage.Stat(meta.RelativePath())
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if err != nil {
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if os.IsNotExist(err) {
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return false, nil
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}
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return false, err
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}
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return true, nil
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}
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// Verify returns true if the object exists in the content store and size is correct.
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func (s *ContentStore) Verify(meta *models.LFSMetaObject) (bool, error) {
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p := meta.RelativePath()
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fi, err := s.ObjectStorage.Stat(p)
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if os.IsNotExist(err) || (err == nil && fi.Size() != meta.Size) {
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return false, nil
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} else if err != nil {
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log.Error("Unable stat file: %s for LFS OID[%s] Error: %v", p, meta.Oid, err)
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return false, err
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}
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return true, nil
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}
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type hashingReader struct {
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internal io.Reader
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currentSize int64
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expectedSize int64
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hash hash.Hash
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expectedHash string
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}
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func (r *hashingReader) Read(b []byte) (int, error) {
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n, err := r.internal.Read(b)
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if n > 0 {
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r.currentSize += int64(n)
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wn, werr := r.hash.Write(b[:n])
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if wn != n || werr != nil {
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return n, werr
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}
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}
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if err != nil && err == io.EOF {
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if r.currentSize != r.expectedSize {
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return n, errSizeMismatch
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}
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shaStr := hex.EncodeToString(r.hash.Sum(nil))
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if shaStr != r.expectedHash {
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return n, errHashMismatch
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}
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}
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return n, err
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}
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func newHashingReader(expectedSize int64, expectedHash string, reader io.Reader) *hashingReader {
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return &hashingReader{
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internal: reader,
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expectedSize: expectedSize,
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expectedHash: expectedHash,
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hash: sha256.New(),
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}
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}
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