f - Reuse private file creation for node entropy

Node entropy mnemonic creation should share the existing private-file write path instead of keeping a separate implementation, while the legacy seed filename should stay scoped to the tests that need it.

Co-Authored-By: HAL 9000

Author: tnull

ldk-server/src/util/entropy.rs

@@ -8,20 +8,17 @@
 // licenses.
 
 use std::fs;
-use std::io::{self, Write};
-use std::os::unix::fs::{OpenOptionsExt, PermissionsExt};
+use std::io;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 
 use ldk_node::bip39::Mnemonic;
 use ldk_node::entropy::{generate_entropy_mnemonic, NodeEntropy};
 use log::info;
 
-use crate::util::config::EntropyConfig;
+use crate::util::{config::EntropyConfig, write_new};
 
 const DEFAULT_MNEMONIC_FILE: &str = "keys_mnemonic";
-#[cfg(test)]
-const LEGACY_SEED_FILE: &str = "keys_seed";
 
 pub(crate) fn load_or_generate_node_entropy(
 	storage_dir: &Path, entropy_config: &EntropyConfig,
@@ -49,7 +46,7 @@ pub(crate) fn load_or_generate_node_entropy(
 			fs::create_dir_all(parent)?;
 		}
 		let mnemonic = generate_entropy_mnemonic(None);
-		write_mnemonic_file(&mnemonic_path, &mnemonic)?;
+		write_new(&mnemonic_path, format!("{}\n", mnemonic).as_bytes(), 0o600)?;
 		info!(
 			"Generated new BIP39 mnemonic at {}. Back up this file securely — it is required to recover on-chain funds.",
 			mnemonic_path.display()
@@ -60,19 +57,12 @@ pub(crate) fn load_or_generate_node_entropy(
 	Ok(NodeEntropy::from_bip39_mnemonic(mnemonic, None))
 }
 
-fn write_mnemonic_file(path: &Path, mnemonic: &Mnemonic) -> io::Result<()> {
-	let mut f = fs::OpenOptions::new().create_new(true).write(true).mode(0o600).open(path)?;
-	f.set_permissions(fs::Permissions::from_mode(0o600))?;
-	writeln!(f, "{}", mnemonic)?;
-	f.sync_all()?;
-	Ok(())
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;
-	use std::os::unix::fs::MetadataExt;
+	use std::os::unix::fs::{MetadataExt, PermissionsExt};
 
+	const LEGACY_SEED_FILE: &str = "keys_seed";
 	const KNOWN_MNEMONIC: &str = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon art";
 
 	fn tempdir(tag: &str) -> PathBuf {