From b8527f4b380093d071469071fd2a9ba6cf40da3d Mon Sep 17 00:00:00 2001
From: Michael Eischer <michael.eischer@fau.de>
Date: Thu, 17 Oct 2024 20:52:14 +0200
Subject: [PATCH] prune: allow dry-run without taking a lock

---
 changelog/unreleased/pull-5096 | 7 +++++++
 cmd/restic/cmd_prune.go        | 6 +++++-
 2 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 changelog/unreleased/pull-5096

diff --git a/changelog/unreleased/pull-5096 b/changelog/unreleased/pull-5096
new file mode 100644
index 000000000..d1e1d09b2
--- /dev/null
+++ b/changelog/unreleased/pull-5096
@@ -0,0 +1,7 @@
+Enhancement: Allow prune dry-run without lock
+
+The `prune --dry-run --no-lock` now allows performing a dry-run without
+taking a lock. If the repository is modified concurrently, `prune` may
+return inaccurate statistics or errors.
+
+https://github.com/restic/restic/pull/5096
diff --git a/cmd/restic/cmd_prune.go b/cmd/restic/cmd_prune.go
index e8473bd6f..a74ba23f7 100644
--- a/cmd/restic/cmd_prune.go
+++ b/cmd/restic/cmd_prune.go
@@ -149,7 +149,11 @@ func runPrune(ctx context.Context, opts PruneOptions, gopts GlobalOptions, term
 		return errors.Fatal("disabled compression and `--repack-uncompressed` are mutually exclusive")
 	}
 
-	ctx, repo, unlock, err := openWithExclusiveLock(ctx, gopts, false)
+	if gopts.NoLock && !opts.DryRun {
+		return errors.Fatal("--no-lock is only applicable in combination with --dry-run for prune command")
+	}
+
+	ctx, repo, unlock, err := openWithExclusiveLock(ctx, gopts, opts.DryRun && gopts.NoLock)
 	if err != nil {
 		return err
 	}