Invalid output in `batch_reader.go`

[KN4CK3R]

strconv.ParseInt: parsing "number": invalid syntax

Steps to reproduce:

1. Create a repository with actions enabled
2. Create a file /.gitea/workflows with the content not a number
3. Create a file /.github/workflows with the content not a number
4. Open the page /<owner>/<repo>/actions
5. If no error is shown, refresh the page multiple times until an error occurs

The reason is this code

gitea/modules/actions/workflows.go

Lines 47 to 50 in ce9978b

	tree, err := commit.SubTree(".gitea/workflows")
	if _, ok := err.(git.ErrNotExist); ok {
	tree, err = commit.SubTree(".github/workflows")
	}

which fails in line 179

gitea/modules/git/batch_reader.go

Lines 152 to 181 in ce9978b

	func ReadBatchLine(rd *bufio.Reader) (sha []byte, typ string, size int64, err error) {
	typ, err = rd.ReadString('\n')
	if err != nil {
	return sha, typ, size, err
	}
	if len(typ) == 1 {
	typ, err = rd.ReadString('\n')
	if err != nil {
	return sha, typ, size, err
	}
	}
	idx := strings.IndexByte(typ, ' ')
	if idx < 0 {
	log.Debug("missing space typ: %s", typ)
	return sha, typ, size, ErrNotExist{ID: string(sha)}
	}
	sha = []byte(typ[:idx])
	typ = typ[idx+1:]
	idx = strings.IndexByte(typ, ' ')
	if idx < 0 {
	return sha, typ, size, ErrNotExist{ID: string(sha)}
	}
	sizeStr := typ[idx+1 : len(typ)-1]
	typ = typ[:idx]
	size, err = strconv.ParseInt(sizeStr, 10, 64)
	return sha, typ, size, err
	}

If the error occurs the code tries to parse not a number as output of the batch reader. A normal output looks like 8b2bfd3a117fcb7ae93f93616cb2f7a9706c513a tree 104. I don't know how the content of a file can be present here. And even worse is that it does not fail every time. If I create only one workflows file it does not fail but that may just be a timing issue.

Git Version

2.43.0, non-gogit

[KN4CK3R]

Stacktrace:

code.gitea.io/gitea/modules/git.ReadBatchLine(0xc0034f5008?)
        /src/modules/git/batch_reader.go:182 +0x1c8
code.gitea.io/gitea/modules/git.(*Repository).getTree(0xc005f8c870, {0x3a90360, 0xc0034f5008})
        /src/modules/git/repo_tree_nogogit.go:19 +0xf0
code.gitea.io/gitea/modules/git.(*Tree).SubTree(0xc004ba2f70, {0x327c01b?, 0x316d8c8?})
        /src/modules/git/tree.go:42 +0x1a5
code.gitea.io/gitea/modules/actions.ListWorkflows(0xc004ba2f70)
        /src/modules/actions/workflows.go:50 +0x85
code.gitea.io/gitea/routers/web/repo/actions.List(0xc004be8c80)
        /src/routers/web/repo/actions/actions.go:74 +0x1d7

[yp05327]

cat-file --batch will output <sha> SP <type> SP <size> LF\n<content>
After some tests, I notice that:
normally, reader buffer will not be empty after read one line, as we have <content> behind.
but reader buffer will randomly be empty after read one line, e.g. we will get <sha> SP <type> SP <size> LF\n in reader bugger without content. And the content will be read at the next time, which caused this bug.

Some related codes:

gitea/modules/git/repo_base_nogogit.go

Lines 81 to 86 in f04e71f

	func (repo *Repository) CatFileBatch(ctx context.Context) (WriteCloserError, *bufio.Reader, func()) {
	if repo.batchCancel == nil || repo.batchReader.Buffered() > 0 {
	log.Debug("Opening temporary cat file batch for: %s", repo.Path)
	return CatFileBatch(ctx, repo.Path)
	}
	return repo.batchWriter, repo.batchReader, func() {}

if repo.batchReader.Buffered() is 0, as what mentioned above, reader buffer will randomly be empty after read one line,
CatFileBatch will return the existing reader buffer , and in for loop in func SubTree, in the next time, func getTree will read <content> as the first line.