From f84d3989899cc1ead3685beeb8fd152d342a8ae6 Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Fri, 21 Nov 2025 22:29:31 +0100
Subject: [PATCH] repository: prevent test deadlock within WithBlobUploader

Calling t.Fatal internally triggers runtime.Goexit . This kills the
current goroutine while only running deferred code. Add an extra context
that gets canceled if the go routine exits while within the user
provided callback.
---
 internal/repository/repository.go | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/internal/repository/repository.go b/internal/repository/repository.go
index 32d2e1aac..e7a1b8c17 100644
--- a/internal/repository/repository.go
+++ b/internal/repository/repository.go
@@ -562,6 +562,8 @@ func (r *Repository) removeUnpacked(ctx context.Context, t restic.FileType, id r
 }
 
 func (r *Repository) WithBlobUploader(ctx context.Context, fn func(ctx context.Context, uploader restic.BlobSaverWithAsync) error) error {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
 	wg, ctx := errgroup.WithContext(ctx)
 	// pack uploader + wg.Go below + blob saver (CPU bound)
 	wg.SetLimit(2 + runtime.GOMAXPROCS(0))
@@ -570,7 +572,18 @@ func (r *Repository) WithBlobUploader(ctx context.Context, fn func(ctx context.C
 	// blob saver are spawned on demand, use wait group to keep track of them
 	r.blobSaver = &sync.WaitGroup{}
 	wg.Go(func() error {
-		if err := fn(ctx, &blobSaverRepo{repo: r}); err != nil {
+		inCallback := true
+		defer func() {
+			// when the defer is called while inCallback is true, this means
+			// that runtime.Goexit was called within `fn`. This should only happen
+			// if a test uses t.Fatal within `fn`.
+			if inCallback {
+				cancel()
+			}
+		}()
+		err := fn(ctx, &blobSaverRepo{repo: r})
+		inCallback = false
+		if err != nil {
 			return err
 		}
 		if err := r.flush(ctx); err != nil {