From ba83881350c0f469f203efe157522b2d98fba4b4 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 23 Aug 2020 21:23:57 +0100
Subject: [PATCH] new config defaulting

---
 src/bin/server.rs |  3 ++-
 src/global.rs     | 21 ++++++++++++++++++---
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/bin/server.rs b/src/bin/server.rs
index 1e23ef66..2a7dd26c 100644
--- a/src/bin/server.rs
+++ b/src/bin/server.rs
@@ -75,7 +75,8 @@ fn main() {
       .unwrap_or(DEFAULT_CONFIG_FILENAME.to_owned());
     let mut buf = String::new();
     File::open(config_filename)?.read_to_string(&mut buf)?;
-    let config = toml::de::from_str(&buf)?;
+    let config : ServerConfigSpec = toml::de::from_str(&buf)?;
+    let config = config.try_into()?;
     set_config(config);
   };
 
diff --git a/src/global.rs b/src/global.rs
index fc6867fb..efe34a75 100644
--- a/src/global.rs
+++ b/src/global.rs
@@ -924,12 +924,25 @@ pub fn client_expire_old_clients() {
 const DEFAULT_SAVE_DIRECTORY : &str = "save";
 
 #[derive(Deserialize,Debug,Clone)]
+pub struct ServerConfigSpec {
+  pub save_directory: Option<String>,
+}
+
+#[derive(Debug,Clone)]
 pub struct ServerConfig {
-  #[serde(default="default_save_directory")]
   pub save_directory: String,
 }
 
-fn default_save_directory() -> String { DEFAULT_SAVE_DIRECTORY.to_owned() }
+impl TryFrom<ServerConfigSpec> for ServerConfig {
+  type Error = AE;
+  #[throws(Self::Error)]
+  fn try_from(spec: ServerConfigSpec) -> ServerConfig {
+    let ServerConfigSpec { save_directory } = spec;
+    let save_directory = save_directory
+      .unwrap_or_else(|| DEFAULT_SAVE_DIRECTORY.to_owned());
+    ServerConfig { save_directory }
+  }
+}
 
 pub fn config() -> Arc<ServerConfig> {
   GLOBAL.config.read().unwrap().clone()
@@ -941,6 +954,8 @@ pub fn set_config(config: ServerConfig) {
 
 impl Default for ServerConfig {
   fn default() -> ServerConfig {
-    toml::de::from_str("").expect("parse empty string as ServerConfig")
+    let spec : ServerConfigSpec = toml::de::from_str("")
+      .expect("parse empty string as ServerConfigSpec");
+    spec.try_into().expect("empty spec into config")
   }
 }
-- 
2.30.2