From 101c1ab3deb100eb9522c689bc8bdaa0728373fd Mon Sep 17 00:00:00 2001 From: Javier Alvarez Garcia Date: Mon, 17 Jun 2024 19:10:33 +0200 Subject: storage: Fix reference updated concurrently error for the filesystem storer If a reference exists in the packed refs file but not in the actual refs folder, we need to fall back to reading the pack refs file when storing the reference. This happens because by the time we are storing the reference, we open the file with write permissions and read from it. At that point, if the file is empty, we still need to read the valid reference. Otherwise, it will read 0, and assume that the references do not match (because the old value was read from the packed file). --- storage/filesystem/dotgit/dotgit.go | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'storage/filesystem/dotgit/dotgit.go') diff --git a/storage/filesystem/dotgit/dotgit.go b/storage/filesystem/dotgit/dotgit.go index ada51eb..72c9ccf 100644 --- a/storage/filesystem/dotgit/dotgit.go +++ b/storage/filesystem/dotgit/dotgit.go @@ -72,6 +72,9 @@ var ( // ErrIsDir is returned when a reference file is attempting to be read, // but the path specified is a directory. ErrIsDir = errors.New("reference path is a directory") + // ErrEmptyRefFile is returned when a reference file is attempted to be read, + // but the file is empty + ErrEmptyRefFile = errors.New("ref file is empty") ) // Options holds configuration for the storage. @@ -661,18 +664,33 @@ func (d *DotGit) readReferenceFrom(rd io.Reader, name string) (ref *plumbing.Ref return nil, err } + if len(b) == 0 { + return nil, ErrEmptyRefFile + } + line := strings.TrimSpace(string(b)) return plumbing.NewReferenceFromStrings(name, line), nil } +// checkReferenceAndTruncate reads the reference from the given file, or the `pack-refs` file if +// the file was empty. Then it checks that the old reference matches the stored reference and +// truncates the file. func (d *DotGit) checkReferenceAndTruncate(f billy.File, old *plumbing.Reference) error { if old == nil { return nil } + ref, err := d.readReferenceFrom(f, old.Name().String()) + if errors.Is(err, ErrEmptyRefFile) { + // This may happen if the reference is being read from a newly created file. + // In that case, try getting the reference from the packed refs file. + ref, err = d.packedRef(old.Name()) + } + if err != nil { return err } + if ref.Hash() != old.Hash() { return storage.ErrReferenceHasChanged } -- cgit