1 files changed, 76 insertions, 0 deletions
diff --git a/toolkit/mozapps/defaultagent/rust/wineventlog/src/lib.rs b/toolkit/mozapps/defaultagent/rust/wineventlog/src/lib.rs
new file mode 100644
index 0000000000..c98b75c53a
--- /dev/null
+++ b/toolkit/mozapps/defaultagent/rust/wineventlog/src/lib.rs
@@ -0,0 +1,76 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Very simple implementation of logging via the Windows Event Log
+
+use std::ffi::OsStr;
+use std::ptr;
+
+use log::{Level, Metadata, Record};
+use winapi::shared::minwindef::WORD;
+use winapi::um::{winbase, winnt};
+use wio::wide::ToWide;
+
+pub struct EventLogger {
+    pub name: Vec<u16>,
+}
+
+impl EventLogger {
+    pub fn new(name: impl AsRef<OsStr>) -> Self {
+        EventLogger {
+            name: name.to_wide_null(),
+        }
+    }
+}
+
+impl log::Log for EventLogger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= log::max_level()
+    }
+
+    fn log(&self, record: &Record) {
+        if !self.enabled(record.metadata()) {
+            return;
+        }
+
+        let name = self.name.as_ptr();
+        let msg = format!("{} - {}", record.level(), record.args()).to_wide_null();
+
+        // Open and close the event log handle on every message, for simplicity.
+        let event_log;
+        unsafe {
+            event_log = winbase::RegisterEventSourceW(ptr::null(), name);
+            if event_log.is_null() {
+                return;
+            }
+        }
+
+        let level = match record.level() {
+            Level::Error => winnt::EVENTLOG_ERROR_TYPE,
+            Level::Warn => winnt::EVENTLOG_WARNING_TYPE,
+            Level::Info | Level::Debug | Level::Trace => winnt::EVENTLOG_INFORMATION_TYPE,
+        };
+
+        unsafe {
+            // mut only to match the LPCWSTR* signature
+            let mut msg_array: [*const u16; 1] = [msg.as_ptr()];
+
+            let _ = winbase::ReportEventW(
+                event_log,
+                level,
+                0,                       // no category
+                0,                       // event id 0
+                ptr::null_mut(),         // no user sid
+                msg_array.len() as WORD, // string count
+                0,                       // 0 bytes raw data
+                msg_array.as_mut_ptr(),  // strings
+                ptr::null_mut(),         // no raw data
+            );
+
+            let _ = winbase::DeregisterEventSource(event_log);
+        }
+    }
+
+    fn flush(&self) {}
+}