x11: Improve xlib error reporting

2 files changed, 22 insertions, 13 deletions

diff --git a/src/api/x11/xdisplay.rs b/src/api/x11/xdisplay.rs
index 2b77d9c..8205c66 100644
--- a/src/api/x11/xdisplay.rs
+++ b/src/api/x11/xdisplay.rs
@@ -23,24 +23,18 @@ pub struct XConnection {
 unsafe impl Send for XConnection {}
 unsafe impl Sync for XConnection {}
 
+pub type XErrorHandler = Option<unsafe extern fn(*mut ffi::Display, *mut ffi::XErrorEvent) -> libc::c_int>;
+
 impl XConnection {
-    pub fn new() -> Result<XConnection, XNotSupported> {
+    pub fn new(error_handler: XErrorHandler) -> Result<XConnection, XNotSupported> {
         // opening the libraries
         let xlib = try!(ffi::Xlib::open());
         let xcursor = try!(ffi::Xcursor::open());
         let xf86vmode = try!(ffi::Xf86vmode::open());
         let xinput2 = try!(ffi::XInput2::open());
 
-        unsafe extern "C" fn x_error_callback(_: *mut ffi::Display, event: *mut ffi::XErrorEvent)
-                                              -> libc::c_int
-        {
-            println!("[glutin] x error code={} major={} minor={}!", (*event).error_code,
-                     (*event).request_code, (*event).minor_code);
-            0
-        }
-
         unsafe { (xlib.XInitThreads)() };
-        unsafe { (xlib.XSetErrorHandler)(Some(x_error_callback)) };
+        unsafe { (xlib.XSetErrorHandler)(error_handler) };
 
         // TODO: use something safer than raw "dlopen"
         let glx = {
diff --git a/src/platform/linux/api_dispatch.rs b/src/platform/linux/api_dispatch.rs
index a3c3bf9..f39ae43 100644
--- a/src/platform/linux/api_dispatch.rs
+++ b/src/platform/linux/api_dispatch.rs
@@ -33,7 +33,7 @@ lazy_static!(
         if false && wayland::is_available() {
             Backend::Wayland
         } else {
-            match XConnection::new() {
+            match XConnection::new(Some(x_error_callback)) {
                 Ok(x) => Backend::X(Arc::new(x)),
                 Err(e) => Backend::Error(e),
             }
@@ -115,7 +115,7 @@ impl MonitorId {
         match self {
             &MonitorId::X(ref m) => m.get_native_identifier(),
             &MonitorId::Wayland(ref m) => m.get_native_identifier(),
-            &MonitorId::None => unimplemented!()        // FIXME: 
+            &MonitorId::None => unimplemented!()        // FIXME:
         }
     }
 
@@ -124,7 +124,7 @@ impl MonitorId {
         match self {
             &MonitorId::X(ref m) => m.get_dimensions(),
             &MonitorId::Wayland(ref m) => m.get_dimensions(),
-            &MonitorId::None => (800, 600),     // FIXME: 
+            &MonitorId::None => (800, 600),     // FIXME:
         }
     }
 }
@@ -390,3 +390,18 @@ impl GlContext for Window {
         }
     }
 }
+
+unsafe extern "C" fn x_error_callback(dpy: *mut x11::ffi::Display, event: *mut x11::ffi::XErrorEvent)
+                                      -> libc::c_int
+{
+    use std::ffi::CStr;
+
+    if let Backend::X(ref x) = *BACKEND {
+        let mut buff: Vec<u8> = Vec::with_capacity(1024);
+        (x.xlib.XGetErrorText)(dpy, (*event).error_code as i32, buff.as_mut_ptr() as *mut i8, buff.capacity() as i32);
+        let error = CStr::from_ptr(buff.as_mut_ptr() as *const i8).to_string_lossy();
+        println!("[glutin] x error code={} major={} minor={}: {}!", (*event).error_code, (*event).request_code, (*event).minor_code, error);
+    }
+
+    0
+}