3 files changed, 39 insertions, 10 deletions

diff --git a/src/app.rs b/src/app.rs
index 3127459..6f7b6a7 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -4,6 +4,11 @@ use super::*;
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct AppId(pub u32);
+impl From<u32> for AppId {
+    fn from(id: u32) -> Self {
+        AppId(id)
+    }
+}
 
 /// Access to the steam apps interface
 pub struct Apps<Manager> {
diff --git a/src/lib.rs b/src/lib.rs
index 1c7cdec..ed373ef 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -119,7 +119,8 @@ impl Client<ClientManager> {
     ///
     ///   If the game isn't being run through steam this can be provided by
     ///   placing a `steam_appid.txt` with the ID inside in the current
-    ///   working directory
+    ///   working directory. Alternatively, you can use `Client::init_app(<app_id>)`
+    ///   to force a specific app ID.
     /// * The game isn't running on the same user/level as the steam client
     /// * The user doesn't own a license for the game.
     /// * The app ID isn't completely set up.
@@ -147,6 +148,25 @@ impl Client<ClientManager> {
             }))
         }
     }
+
+    /// Attempts to initialize the steamworks api **for a specified app ID**
+    /// and returns a client to access the rest of the api.
+    ///
+    /// This should only ever have one instance per a program.
+    ///
+    /// # Errors
+    ///
+    /// This can fail if:
+    /// * The steam client isn't running
+    /// * The game isn't running on the same user/level as the steam client
+    /// * The user doesn't own a license for the game.
+    /// * The app ID isn't completely set up.
+    pub fn init_app<ID: Into<AppId>>(app_id: ID) -> SResult<(Client<ClientManager>, SingleClient<ClientManager>)> {
+        let app_id = app_id.into().0.to_string();
+        std::env::set_var("SteamAppId", &app_id);
+        std::env::set_var("SteamGameId", app_id);
+        Client::init()
+    }
 }
 impl <M> SingleClient<M> where M: Manager {
     /// Runs any currently pending callbacks
diff --git a/src/ugc.rs b/src/ugc.rs
index 1609d4b..d98bf8a 100644
--- a/src/ugc.rs
+++ b/src/ugc.rs
@@ -299,21 +299,23 @@ bitflags! {
 pub struct DownloadItemResult {
     pub app_id: AppId,
     pub published_file_id: PublishedFileId,
+    pub error: Option<SteamError>,
 }
 
-unsafe impl Callback for Result<DownloadItemResult, SteamError> {
+unsafe impl Callback for DownloadItemResult {
     const ID: i32 = CALLBACK_BASE_ID + 6;
     const SIZE: i32 = ::std::mem::size_of::<sys::DownloadItemResult_t>() as i32;
 
     unsafe fn from_raw(raw: *mut c_void) -> Self {
         let val = &mut *(raw as *mut sys::DownloadItemResult_t);
-        if val.m_eResult == sys::EResult::k_EResultOK {
-            Ok(DownloadItemResult {
-                app_id: AppId(val.m_unAppID),
-                published_file_id: PublishedFileId(val.m_nPublishedFileId),
-            })
-        } else {
-            Err(val.m_eResult.into())
+        DownloadItemResult {
+            app_id: AppId(val.m_unAppID),
+            published_file_id: PublishedFileId(val.m_nPublishedFileId),
+
+            error: match val.m_eResult {
+                sys::EResult::k_EResultOK => None,
+                error => Some(error.into())
+            }
         }
     }
 }
@@ -1253,7 +1255,8 @@ impl<'a> QueryResults<'a> {
                 num_children: raw_details.m_unNumChildren,
                 tags,
                 tags_truncated: raw_details.m_bTagsTruncated,
-                file_type: raw_details.m_eFileType.into()
+                file_type: raw_details.m_eFileType.into(),
+                file_size: raw_details.m_nFileSize.max(0) as u32,
             })
         }
     }
@@ -1354,6 +1357,7 @@ pub struct QueryResult {
     pub tags: Vec<String>,
     pub tags_truncated: bool,
     pub file_type: FileType,
+    pub file_size: u32,
 
     pub url: String,
     pub num_upvotes: u32,