From 4909aa0a29f317bd9a89805c5847fdfd898c3836 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Thu, 20 Feb 2025 01:46:42 +0100
Subject: [PATCH] Don't migrate existing data dir without version number

If there is a directory but no version number, we have no idea what's
going on. If we continue the migration, we might overwrite or break some
other program's data.
---
 gdn/src/data.rs         | 6 ++++--
 gdn/src/data/datadir.rs | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/gdn/src/data.rs b/gdn/src/data.rs
index 29fcd14..a405bee 100644
--- a/gdn/src/data.rs
+++ b/gdn/src/data.rs
@@ -15,10 +15,12 @@ pub use self::{
 
 fn migrate(dir: &LockedDataDir) -> anyhow::Result<()> {
     loop {
-        match dir.read_version()? {
-            0 => v0::migrate(dir)?,
+        let version = dir.read_version().context("failed to migrate data dir")?;
+        match version {
+            0 => v0::migrate(dir),
             _ => break Ok(()),
         }
+        .with_context(|| format!("failed to migrate data dir from version {version}"))?;
     }
 }
 
diff --git a/gdn/src/data/datadir.rs b/gdn/src/data/datadir.rs
index 6b23866..c4ee5bf 100644
--- a/gdn/src/data/datadir.rs
+++ b/gdn/src/data/datadir.rs
@@ -104,6 +104,7 @@ impl UnlockedDataDir {
     pub(super) fn read_version(&self) -> anyhow::Result<u32> {
         let path = self.version_file();
         match self.read_string_optional(&path)? {
+            None if self.path.exists() => Err(anyhow!("found data dir without version number")),
             None => Ok(0),
             Some(string) => Ok(string.trim().parse().with_context(|| {
                 format!("failed to parse {} as version number", path.display())