chore(code): split much of the efi support code to crates/eficore

crates/eficore/src/logger.rs

@@ -0,0 +1,94 @@
+//! Based on: https://github.com/rust-osdev/uefi-rs/blob/main/uefi/src/helpers/logger.rs
+
+use alloc::format;
+use core::fmt::Write;
+use core::ptr;
+use core::sync::atomic::{AtomicPtr, Ordering};
+use log::{Log, Record};
+use uefi::proto::console::text::Output;
+
+/// The global logger object.
+static LOGGER: Logger = Logger::new();
+
+/// Logging mechanism for Sprout.
+/// Must be initialized to be used, as we use atomic pointers to store the output to write to.
+pub struct Logger {
+    writer: AtomicPtr<Output>,
+}
+
+impl Default for Logger {
+    /// Creates a default logger, which is uninitialized with an output.
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Logger {
+    /// Create a new logger with an output not specified.
+    /// This will cause the logger to not print anything until it is configured.
+    pub const fn new() -> Self {
+        Self {
+            writer: AtomicPtr::new(ptr::null_mut()),
+        }
+    }
+
+    /// Retrieves the pointer to the output.
+    /// SAFETY: This pointer might be null, it should be checked before use.
+    #[must_use]
+    fn output(&self) -> *mut Output {
+        self.writer.load(Ordering::Acquire)
+    }
+
+    /// Sets the output to write to.
+    ///
+    /// # Safety
+    /// This function is unsafe because the output is technically leaked and unmanaged.
+    pub unsafe fn set_output(&self, output: *mut Output) {
+        self.writer.store(output, Ordering::Release);
+    }
+}
+
+impl Log for Logger {
+    /// Enable the logger always.
+    fn enabled(&self, _metadata: &log::Metadata<'_>) -> bool {
+        true
+    }
+
+    /// Log the specified `record` to the output if one is set.
+    fn log(&self, record: &Record) {
+        // Acquire the output. If one is not set, we do nothing.
+        let Some(output) = (unsafe { self.output().as_mut() }) else {
+            return;
+        };
+
+        // Format the log message.
+        let message = format!("{}", record.args());
+
+        // Iterate over every line, formatting the message and writing it to the output.
+        for line in message.lines() {
+            // The format writes the log level in front of every line of text.
+            let _ = writeln!(output, "[{:>5}] {}", record.level(), line);
+        }
+    }
+
+    /// This log is not buffered, so flushing isn't required.
+    fn flush(&self) {}
+}
+
+/// Initialize the logging environment, calling panic if something goes wrong.
+pub fn init() {
+    // Retrieve the stdout handle and set it as the output for the global logger.
+    uefi::system::with_stdout(|stdout| unsafe {
+        // SAFETY: We are using the stdout handle to create a pointer to the output.
+        // The handle is global and is guaranteed to be valid for the lifetime of the program.
+        LOGGER.set_output(stdout);
+    });
+
+    // Set the logger to the global logger.
+    if let Err(error) = log::set_logger(&LOGGER) {
+        panic!("unable to set logger: {}", error);
+    }
+
+    // Set the max level to the level specified by the log features.
+    log::set_max_level(log::STATIC_MAX_LEVEL);
+}