From e28a38abc504f483518f51bd516d64d4dd87eaf4 Mon Sep 17 00:00:00 2001
From: PThorpe92 <preston@turso.tech>
Date: Fri, 15 Aug 2025 22:40:25 -0400
Subject: [PATCH] Fix wal tag safety issues, and add debug assertion that we
 are reading the proper frames

---
 core/storage/pager.rs          | 1 +
 core/storage/sqlite3_ondisk.rs | 3 +++
 core/storage/wal.rs            | 8 +-------
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/core/storage/pager.rs b/core/storage/pager.rs
index d1da59d4b..a0f36d749 100644
--- a/core/storage/pager.rs
+++ b/core/storage/pager.rs
@@ -287,6 +287,7 @@ impl Page {
         self.get().wal_tag.store(TAG_UNSET, Ordering::Release)
     }
 
+    #[inline]
     pub fn is_valid_for_checkpoint(&self, target_frame: u64, seq: u32) -> bool {
         let (f, s) = self.wal_tag_pair();
         f == target_frame && s == seq && !self.is_dirty()
diff --git a/core/storage/sqlite3_ondisk.rs b/core/storage/sqlite3_ondisk.rs
index c11682dbf..36537d024 100644
--- a/core/storage/sqlite3_ondisk.rs
+++ b/core/storage/sqlite3_ondisk.rs
@@ -912,6 +912,9 @@ pub fn finish_read_page(page_idx: usize, buffer_ref: Arc<Buffer>, page: PageRef)
         page.get().contents.replace(inner);
         page.clear_locked();
         page.set_loaded();
+        // we set the wal tag only when reading page from log, or in allocate_page,
+        // we clear it here for safety in case page is being re-loaded.
+        page.clear_wal_tag();
     }
 }
 
diff --git a/core/storage/wal.rs b/core/storage/wal.rs
index c4eda17bb..79b7cb75a 100644
--- a/core/storage/wal.rs
+++ b/core/storage/wal.rs
@@ -1375,12 +1375,6 @@ impl WalFile {
         shared: Arc<UnsafeCell<WalFileShared>>,
         buffer_pool: Arc<BufferPool>,
     ) -> Self {
-        let checkpoint_page = Arc::new(Page::new(0));
-        let buffer = buffer_pool.get_page();
-        {
-            checkpoint_page.get().contents = Some(PageContent::new(0, Arc::new(buffer)));
-        }
-
         let header = unsafe { shared.get().as_mut().unwrap().wal_header.lock() };
         let last_checksum = unsafe { (*shared.get()).last_checksum };
         let disable_checkpoint_cache =
@@ -1813,7 +1807,7 @@ impl WalFile {
     /// Must be invoked while writer and checkpoint locks are still held.
     fn restart_log(&mut self, mode: CheckpointMode) -> Result<()> {
         turso_assert!(
-            matches!(mode, CheckpointMode::Restart | CheckpointMode::Truncate),
+            mode.should_restart_log(),
             "CheckpointMode must be Restart or Truncate"
         );
         turso_assert!(