From 7c44dcd682892f682bc5c98ed40c0fe1606de087 Mon Sep 17 00:00:00 2001
From: Valentine Wallace <vwallace@protonmail.com>
Date: Tue, 16 Feb 2021 20:22:53 -0500
Subject: [PATCH] trying atomic rename thing

---
 lightning-persister/Cargo.toml  |  3 +++
 lightning-persister/src/util.rs | 47 ++++++++++++++++++++++++++++++---
 2 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/lightning-persister/Cargo.toml b/lightning-persister/Cargo.toml
index 63b69a1e1..a6c464554 100644
--- a/lightning-persister/Cargo.toml
+++ b/lightning-persister/Cargo.toml
@@ -16,5 +16,8 @@ libc = "0.2"
 version = "0.24"
 features = ["bitcoinconsensus"]
 
+[target.'cfg(windows)'.dependencies]
+winapi = { version = "0.3", features = ["winbase"] }
+
 [dev-dependencies]
 lightning = { version = "0.0.12", path = "../lightning", features = ["_test_utils"] }
diff --git a/lightning-persister/src/util.rs b/lightning-persister/src/util.rs
index 004bc5d67..7d63a4156 100644
--- a/lightning-persister/src/util.rs
+++ b/lightning-persister/src/util.rs
@@ -1,6 +1,14 @@
+
+#[cfg(target_os = "windows")]
+extern crate winapi;
+
 use std::fs;
 use std::path::{Path, PathBuf};
-
+#[cfg(target_os = "windows")]
+	use {
+		std::ffi::OsStr,
+		std::os::windows::ffi::OsStrExt
+		};
 #[cfg(not(target_os = "windows"))]
 use std::os::unix::io::AsRawFd;
 
@@ -13,12 +21,34 @@ pub(crate) fn get_full_filepath(filepath: String, filename: String) -> String {
 	path.push(filename);
 	path.to_str().unwrap().to_string()
 }
+#[cfg(target_os = "windows")]
+macro_rules! call {
+	($e: expr) => (
+		if $e != 0 {
+			return Ok(())
+		} else {
+			return Err(std::io::Error::last_os_error())
+		}
+	)
+}
+
+#[cfg(target_os = "windows")]
+fn path_to_windows_str<T: AsRef<OsStr>>(x: T) -> Vec<winapi::shared::ntdef::WCHAR> {
+	x.as_ref().encode_wide().chain(Some(0)).collect()
+}
 
 #[allow(bare_trait_objects)]
 pub(crate) fn write_to_file<D: DiskWriteable>(path: String, filename: String, data: &D) -> std::io::Result<()> {
 	println!("VMW: creating dir");
 	fs::create_dir_all(path.clone())?;
 	println!("VMW: created dir");
+
+	println!("VMW: entries in dir:");
+	let dir = PathBuf::from(path.clone());
+	for entry in fs::read_dir(dir).unwrap() {
+		let entry = entry.unwrap();
+		println!("VMW: entry in dir: {:?}", entry.path());
+	}
 	// Do a crazy dance with lots of fsync()s to be overly cautious here...
 	// We never want to end up in a state where we've lost the old data, or end up using the
 	// old data on power loss after we've returned.
@@ -38,16 +68,25 @@ pub(crate) fn write_to_file<D: DiskWriteable>(path: String, filename: String, da
 		f.sync_all()?;
 		println!("VMW: sync'd all");
 	}
-	println!("VMW: about to rename");
-	fs::rename(&tmp_filename, &filename_with_path)?;
-	println!("VMW: renamed");
 	// Fsync the parent directory on Unix.
 	#[cfg(not(target_os = "windows"))]
 	{
+		fs::rename(&tmp_filename, &filename_with_path)?;
 		let path = Path::new(&filename_with_path).parent().unwrap();
 		let dir_file = fs::OpenOptions::new().read(true).open(path)?;
 		unsafe { libc::fsync(dir_file.as_raw_fd()); }
 	}
+	#[cfg(target_os = "windows")]
+	{
+		println!("VMW: about to rename");
+		let src = PathBuf::from(tmp_filename);
+		let dst = PathBuf::from(filename_with_path);
+		call!(unsafe {winapi::um::winbase::MoveFileExW(
+			path_to_windows_str(src).as_ptr(), path_to_windows_str(dst).as_ptr(),
+			winapi::um::winbase::MOVEFILE_WRITE_THROUGH | winapi::um::winbase::MOVEFILE_REPLACE_EXISTING
+		)});
+		println!("VMW: renamed");
+	}
 	Ok(())
 }
 
-- 
2.39.5