populate timeZoneName as expected by UI

This works by a nasty hack, but it seems to work well enough for now.
Fingers crossed.

src/cmds/run.rs

@@ -42,6 +42,11 @@ use tokio_core::reactor;
 use tokio_signal::unix::{Signal, SIGINT, SIGTERM};
 use web;
 
+// These are used in a hack to get the name of the current time zone (e.g. America/Los_Angeles).
+// They seem to be correct for Linux and OS X at least.
+const LOCALTIME_PATH: &'static str = "/etc/localtime";
+const ZONEINFO_PATH: &'static str = "/usr/share/zoneinfo/";
+
 const USAGE: &'static str = r#"
 Usage: moonfire-nvr run [options]
 
@@ -77,6 +82,16 @@ fn setup_shutdown_future(h: &reactor::Handle) -> Box<Future<Item = (), Error = (
                 .map_err(|_| ()))
 }
 
+fn resolve_zone() -> String {
+    let p = ::std::fs::read_link(LOCALTIME_PATH).expect("unable to read localtime symlink");
+    let p = p.to_str().expect("localtime symlink destination must be valid UTF-8");
+    if !p.starts_with(ZONEINFO_PATH) {
+        panic!("Expected {} to point to a path within {}; actually points to {}",
+               LOCALTIME_PATH, ZONEINFO_PATH, p);
+    }
+    p[ZONEINFO_PATH.len()..].into()
+}
+
 pub fn run() -> Result<(), Error> {
     let args: Args = super::parse_args(USAGE)?;
     let (_db_dir, conn) = super::open_conn(
@@ -86,7 +101,7 @@ pub fn run() -> Result<(), Error> {
     let dir = dir::SampleFileDir::new(&args.flag_sample_file_dir, db.clone()).unwrap();
     info!("Database is loaded.");
 
-    let s = web::Service::new(db.clone(), dir.clone(), Some(&args.flag_ui_dir))?;
+    let s = web::Service::new(db.clone(), dir.clone(), Some(&args.flag_ui_dir), resolve_zone())?;
 
     // Start a streamer for each camera.
     let shutdown_streamers = Arc::new(AtomicBool::new(false));

src/json.rs

@@ -34,10 +34,13 @@ use std::collections::BTreeMap;
 use uuid::Uuid;
 
 #[derive(Debug, Serialize)]
-pub struct ListCameras<'a> {
+#[serde(rename_all="camelCase")]
+pub struct TopLevel<'a> {
+    pub time_zone_name: &'a str,
+
     // Use a custom serializer which presents the map's values as a sequence and includes the
     // "days" attribute or not, according to the bool in the tuple.
-    #[serde(serialize_with = "ListCameras::serialize_cameras")]
+    #[serde(serialize_with = "TopLevel::serialize_cameras")]
     pub cameras: (&'a BTreeMap<i32, db::Camera>, bool),
 }
 
@@ -104,9 +107,8 @@ struct CameraDayValue {
     pub total_duration_90k: i64,
 }
 
-impl<'a> ListCameras<'a> {
+impl<'a> TopLevel<'a> {
-    /// Serializes cameras as a list (rather than a map), wrapping each camera in the
+    /// Serializes cameras as a list (rather than a map), optionally including the `days` field.
-    /// `ListCamerasCamera` type to tweak the data returned.
     fn serialize_cameras<S>(cameras: &(&BTreeMap<i32, db::Camera>, bool),
                             serializer: S) -> Result<S::Ok, S::Error>
     where S: Serializer {

src/web.rs

@@ -172,6 +172,7 @@ struct ServiceInner {
     dir: Arc<SampleFileDir>,
     ui_files: HashMap<String, UiFile>,
     pool: futures_cpupool::CpuPool,
+    time_zone_name: String,
 }
 
 impl ServiceInner {
@@ -197,7 +198,10 @@ impl ServiceInner {
 
         let buf = {
             let db = self.db.lock();
-            serde_json::to_vec(&json::ListCameras{cameras: (db.cameras_by_id(), days)})?
+            serde_json::to_vec(&json::TopLevel {
+                time_zone_name: &self.time_zone_name,
+                cameras: (db.cameras_by_id(), days),
+            })?
         };
         let len = buf.len();
         let body: slices::Body = Box::new(stream::once(Ok(ARefs::new(buf))));
@@ -390,7 +394,7 @@ impl ServiceInner {
 pub struct Service(Arc<ServiceInner>);
 
 impl Service {
-    pub fn new(db: Arc<db::Database>, dir: Arc<SampleFileDir>, ui_dir: Option<&str>)
+    pub fn new(db: Arc<db::Database>, dir: Arc<SampleFileDir>, ui_dir: Option<&str>, zone: String)
                -> Result<Self, Error> {
         let mut ui_files = HashMap::new();
         if let Some(d) = ui_dir {
@@ -402,6 +406,7 @@ impl Service {
             dir,
             ui_files,
             pool: futures_cpupool::Builder::new().pool_size(1).name_prefix("static").create(),
+            time_zone_name: zone,
         })))
     }