fix(lfs): gogit /settings/lfs/find 500 error (#3472)

Refs: https://codeberg.org/forgejo/forgejo/pulls/3448
Refs: https://codeberg.org/forgejo/forgejo/issues/3438
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3472
Reviewed-by: oliverpool <oliverpool@noreply.codeberg.org>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

modules/git/pipeline/lfs_gogit.go

@@ -0,0 +1,146 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build gogit
+
+package pipeline
+
+import (
+	"bufio"
+	"io"
+	"sort"
+	"strings"
+	"sync"
+
+	"code.gitea.io/gitea/modules/git"
+
+	gogit "github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
+)
+
+// FindLFSFile finds commits that contain a provided pointer file hash
+func FindLFSFile(repo *git.Repository, objectID git.ObjectID) ([]*LFSResult, error) {
+	resultsMap := map[string]*LFSResult{}
+	results := make([]*LFSResult, 0)
+
+	basePath := repo.Path
+	gogitRepo := repo.GoGitRepo()
+
+	commitsIter, err := gogitRepo.Log(&gogit.LogOptions{
+		Order: gogit.LogOrderCommitterTime,
+		All:   true,
+	})
+	if err != nil {
+		return nil, lfsError("failed to get GoGit CommitsIter", err)
+	}
+
+	err = commitsIter.ForEach(func(gitCommit *object.Commit) error {
+		tree, err := gitCommit.Tree()
+		if err != nil {
+			return err
+		}
+		treeWalker := object.NewTreeWalker(tree, true, nil)
+		defer treeWalker.Close()
+		for {
+			name, entry, err := treeWalker.Next()
+			if err == io.EOF {
+				break
+			}
+			if entry.Hash == plumbing.Hash(objectID.RawValue()) {
+				parents := make([]git.ObjectID, len(gitCommit.ParentHashes))
+				for i, parentCommitID := range gitCommit.ParentHashes {
+					parents[i] = git.ParseGogitHash(parentCommitID)
+				}
+
+				result := LFSResult{
+					Name:         name,
+					SHA:          gitCommit.Hash.String(),
+					Summary:      strings.Split(strings.TrimSpace(gitCommit.Message), "\n")[0],
+					When:         gitCommit.Author.When,
+					ParentHashes: parents,
+				}
+				resultsMap[gitCommit.Hash.String()+":"+name] = &result
+			}
+		}
+		return nil
+	})
+	if err != nil && err != io.EOF {
+		return nil, lfsError("failure in CommitIter.ForEach", err)
+	}
+
+	for _, result := range resultsMap {
+		hasParent := false
+		for _, parentHash := range result.ParentHashes {
+			if _, hasParent = resultsMap[parentHash.String()+":"+result.Name]; hasParent {
+				break
+			}
+		}
+		if !hasParent {
+			results = append(results, result)
+		}
+	}
+
+	sort.Sort(lfsResultSlice(results))
+
+	// Should really use a go-git function here but name-rev is not completed and recapitulating it is not simple
+	shasToNameReader, shasToNameWriter := io.Pipe()
+	nameRevStdinReader, nameRevStdinWriter := io.Pipe()
+	errChan := make(chan error, 1)
+	wg := sync.WaitGroup{}
+	wg.Add(3)
+
+	go func() {
+		defer wg.Done()
+		scanner := bufio.NewScanner(nameRevStdinReader)
+		i := 0
+		for scanner.Scan() {
+			line := scanner.Text()
+			if len(line) == 0 {
+				continue
+			}
+			result := results[i]
+			result.FullCommitName = line
+			result.BranchName = strings.Split(line, "~")[0]
+			i++
+		}
+	}()
+	go NameRevStdin(repo.Ctx, shasToNameReader, nameRevStdinWriter, &wg, basePath)
+	go func() {
+		defer wg.Done()
+		defer shasToNameWriter.Close()
+		for _, result := range results {
+			i := 0
+			if i < len(result.SHA) {
+				n, err := shasToNameWriter.Write([]byte(result.SHA)[i:])
+				if err != nil {
+					errChan <- err
+					break
+				}
+				i += n
+			}
+			n := 0
+			for n < 1 {
+				n, err = shasToNameWriter.Write([]byte{'\n'})
+				if err != nil {
+					errChan <- err
+					break
+				}
+
+			}
+
+		}
+	}()
+
+	wg.Wait()
+
+	select {
+	case err, has := <-errChan:
+		if has {
+			return nil, lfsError("unable to obtain name for LFS files", err)
+		}
+	default:
+	}
+
+	return results, nil
+}