From 78e3ec3df093a0a8d69b122f45ea26f53cc8a038 Mon Sep 17 00:00:00 2001
From: Antioch Peverell <apeverell@protonmail.com>
Date: Wed, 19 Aug 2020 09:37:22 +0100
Subject: [PATCH] sync_all() on leaf_set and prune_list when using temp file
 (#3354)

---
 store/src/leaf_set.rs   |  6 ++----
 store/src/lib.rs        | 15 ++++++++-------
 store/src/prune_list.rs |  8 +++-----
 3 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/store/src/leaf_set.rs b/store/src/leaf_set.rs
index c2c4b4ae4..ed5477dc6 100644
--- a/store/src/leaf_set.rs
+++ b/store/src/leaf_set.rs
@@ -171,10 +171,8 @@ impl LeafSet {
 		self.bitmap.run_optimize();
 
 		// Write the updated bitmap file to disk.
-		save_via_temp_file(&self.path, ".tmp", |w| {
-			let mut w = BufWriter::new(w);
-			w.write_all(&self.bitmap.serialize())?;
-			w.flush()
+		save_via_temp_file(&self.path, ".tmp", |file| {
+			file.write_all(&self.bitmap.serialize())
 		})?;
 
 		// Make sure our backup in memory is up to date.
diff --git a/store/src/lib.rs b/store/src/lib.rs
index e9e7a17b1..ac2e0800a 100644
--- a/store/src/lib.rs
+++ b/store/src/lib.rs
@@ -75,6 +75,7 @@ pub fn u64_to_key(prefix: u8, val: u64) -> Vec<u8> {
 use std::ffi::OsStr;
 use std::fs::{remove_file, rename, File};
 use std::path::Path;
+
 /// Creates temporary file with name created by adding `temp_suffix` to `path`.
 /// Applies writer function to it and renames temporary file into original specified by `path`.
 pub fn save_via_temp_file<F, P, E>(
@@ -83,7 +84,7 @@ pub fn save_via_temp_file<F, P, E>(
 	mut writer: F,
 ) -> Result<(), std::io::Error>
 where
-	F: FnMut(Box<dyn std::io::Write>) -> Result<(), std::io::Error>,
+	F: FnMut(&mut File) -> Result<(), std::io::Error>,
 	P: AsRef<Path>,
 	E: AsRef<OsStr>,
 {
@@ -99,13 +100,13 @@ where
 		remove_file(&temp_path)?;
 	}
 
-	let file = File::create(&temp_path)?;
-	writer(Box::new(file))?;
+	let mut temp_file = File::create(&temp_path)?;
 
-	// Move temporary file into original
-	if original.exists() {
-		remove_file(&original)?;
-	}
+	// write the new data to the temp file
+	writer(&mut temp_file)?;
+
+	// force an fsync on the temp file to ensure bytes are on disk
+	temp_file.sync_all()?;
 
 	rename(&temp_path, &original)?;
 
diff --git a/store/src/prune_list.rs b/store/src/prune_list.rs
index 64e27ce63..122700a1f 100644
--- a/store/src/prune_list.rs
+++ b/store/src/prune_list.rs
@@ -21,7 +21,7 @@
 //! must be shifted the appropriate amount when reading from the hash and data
 //! files.
 
-use std::io::{self, BufWriter, Write};
+use std::io::{self, Write};
 use std::path::{Path, PathBuf};
 
 use croaring::Bitmap;
@@ -114,10 +114,8 @@ impl PruneList {
 
 		// Write the updated bitmap file to disk.
 		if let Some(ref path) = self.path {
-			save_via_temp_file(path, ".tmp", |w| {
-				let mut w = BufWriter::new(w);
-				w.write_all(&self.bitmap.serialize())?;
-				w.flush()
+			save_via_temp_file(path, ".tmp", |file| {
+				file.write_all(&self.bitmap.serialize())
 			})?;
 		}