Add Utils::set_warning_callback for logging Steam warnings

2 files changed, 55 insertions, 1 deletions

diff --git a/src/lib.rs b/src/lib.rs
index ce40d56..1bcf828 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,8 @@ extern crate steamworks_sys as sys;
 extern crate failure;
 #[macro_use]
 extern crate bitflags;
+#[macro_use]
+extern crate lazy_static;
 
 mod error;
 pub use crate::error::*;
diff --git a/src/utils.rs b/src/utils.rs
index 34ba6c9..3d569b3 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -1,6 +1,12 @@
 
 use super::*;
 
+use libc::c_char;
+use std::ffi::CStr;
+use std::panic;
+use std::process::abort;
+use std::sync::RwLock;
+
 /// Access to the steam utils interface
 pub struct Utils<Manager> {
     pub(crate) utils: *mut sys::ISteamUtils,
@@ -14,6 +20,36 @@ pub enum NotificationPosition {
     BottomRight,
 }
 
+lazy_static!{
+    /// Global rust warning callback
+    static ref WARNING_CALLBACK: RwLock<Option<Box<Fn(i32, &CStr) + Send + Sync>>> = RwLock::new(None);
+}
+
+/// C function to pass as the real callback, which forwards to the `WARNING_CALLBACK` if any
+unsafe extern "cdecl" fn c_warning_callback(level: i32, msg: *const c_char) {
+    let lock = WARNING_CALLBACK.read().expect("warning func lock poisoned");
+    let cb = match lock.as_ref() {
+        Some(cb) => cb,
+        None => { return; }
+    };
+
+    let s = CStr::from_ptr(msg);
+
+    let res = panic::catch_unwind(panic::AssertUnwindSafe(||
+        cb(level, s)
+    ));
+    if let Err(err) = res {
+        if let Some(err) = err.downcast_ref::<&str>() {
+            println!("Steam warning callback paniced: {}", err);
+        } else if let Some(err) = err.downcast_ref::<String>() {
+            println!("Steam warning callback paniced: {}", err);
+        } else {
+            println!("Steam warning callback paniced");
+        }
+        abort();
+    }
+}
+
 impl <Manager> Utils<Manager> {
     /// Returns the app ID of the current process
     pub fn app_id(&self) -> AppId {
@@ -47,4 +83,20 @@ impl <Manager> Utils<Manager> {
             sys::SteamAPI_ISteamUtils_SetOverlayNotificationPosition(self.utils, position);
         }
     }
-}
\ No newline at end of file
+
+    /// Sets the Steam warning callback, which is called to emit warning messages.
+    ///
+    /// The passed-in function takes two arguments: a severity level (0 = info, 1 = warning) and
+    /// the message itself.
+    ///
+    /// See [Steamwork's debugging page](https://partner.steamgames.com/doc/sdk/api/debugging) for more info.
+    pub fn set_warning_callback<F>(&self, cb: F)
+        where F: Fn(i32, &CStr) + Send + Sync + 'static
+    {
+        let mut lock = WARNING_CALLBACK.write().expect("warning func lock poisoned");
+        *lock = Some(Box::new(cb));
+        unsafe {
+            sys::SteamAPI_ISteamUtils_SetWarningMessageHook(self.utils, c_warning_callback);
+        }
+    }
+}