Resolve remaining clippy warnings

Author: phil-opp

bios/boot_sector/src/main.rs

@@ -2,7 +2,10 @@
 #![no_main]
 #![warn(unsafe_op_in_unsafe_fn)]
 
-use core::{arch::global_asm, slice};
+use core::{
+    arch::{asm, global_asm},
+    slice,
+};
 use fail::{print_char, UnwrapOrFail};
 
 global_asm!(include_str!("boot.s"));
@@ -73,5 +76,7 @@ pub extern "C" fn first_stage(disk_number: u16) {
         print_char(b'R');
     }
 
-    loop {}
+    loop {
+        unsafe { asm!("hlt") }
+    }
 }

bios/common/src/lib.rs

@@ -62,3 +62,7 @@ pub struct E820MemoryRegion {
     pub region_type: u32,
     pub acpi_extended_attributes: u32,
 }
+
+pub fn hlt() {
+    unsafe { core::arch::asm!("hlt") };
+}

bios/common/src/racy_cell.rs

@@ -7,6 +7,11 @@ impl<T> RacyCell<T> {
         Self(UnsafeCell::new(v))
     }
 
+    /// Gets a mutable pointer to the wrapped value.
+    ///
+    /// ## Safety
+    /// Ensure that the access is unique (no active references, mutable or not).
+    #[allow(clippy::mut_from_ref)]
     pub unsafe fn get_mut(&self) -> &mut T {
         unsafe { &mut *self.0.get() }
     }

bios/stage-2/src/fat.rs

@@ -28,7 +28,7 @@ struct Bpb {
     fat_size_16: u16,
     total_sectors_32: u32,
     fat_size_32: u32,
-    root_cluster: u32,
+    _root_cluster: u32,
 }
 
 impl Bpb {
@@ -71,7 +71,7 @@ impl Bpb {
             fat_size_16,
             total_sectors_32,
             fat_size_32,
-            root_cluster,
+            _root_cluster: root_cluster,
         }
     }
 
@@ -209,7 +209,7 @@ impl<D: Read + Seek> FileSystem<D> {
     ) -> impl Iterator<Item = Result<RawDirectoryEntry, ()>> + 'a {
         match self.bpb.fat_type() {
             FatType::Fat32 => {
-                self.bpb.root_cluster;
+                // self.bpb.root_cluster;
                 unimplemented!();
             }
             FatType::Fat12 | FatType::Fat16 => {

bios/stage-2/src/main.rs

@@ -7,7 +7,7 @@ use crate::{
         copy_to_protected_mode, enter_protected_mode_and_jump_to_stage_3, enter_unreal_mode,
     },
 };
-use bootloader_x86_64_bios_common::{BiosFramebufferInfo, BiosInfo, Region};
+use bootloader_x86_64_bios_common::{hlt, BiosFramebufferInfo, BiosInfo, Region};
 use byteorder::{ByteOrder, LittleEndian};
 use core::{fmt::Write as _, slice};
 use disk::AlignedArrayBuffer;
@@ -50,12 +50,12 @@ fn start(disk_number: u16, partition_table_start: *const u8) -> ! {
 
         let mut entries = [PartitionTableEntry::empty(); MAX_ENTRIES];
         let raw = unsafe { slice::from_raw_parts(partition_table_start, ENTRY_SIZE * MAX_ENTRIES) };
-        for idx in 0..MAX_ENTRIES {
+        for (idx, entry) in entries.iter_mut().enumerate() {
             let offset = idx * ENTRY_SIZE;
             let partition_type = PartitionType::from_mbr_tag_byte(raw[offset + 4]);
             let lba = LittleEndian::read_u32(&raw[offset + 8..]);
             let len = LittleEndian::read_u32(&raw[offset + 12..]);
-            entries[idx] = PartitionTableEntry::new(partition_type, lba, len);
+            *entry = PartitionTableEntry::new(partition_type, lba, len);
         }
         entries
     };
@@ -146,7 +146,9 @@ fn start(disk_number: u16, partition_table_start: *const u8) -> ! {
 
     enter_protected_mode_and_jump_to_stage_3(STAGE_3_DST, &mut info);
 
-    loop {}
+    loop {
+        hlt();
+    }
 }
 
 fn load_file(

bios/stage-3/src/main.rs

@@ -3,7 +3,7 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
 use crate::screen::Writer;
-use bootloader_x86_64_bios_common::BiosInfo;
+use bootloader_x86_64_bios_common::{hlt, BiosInfo};
 use core::{arch::asm, fmt::Write as _};
 
 mod gdt;
@@ -24,7 +24,9 @@ pub extern "C" fn _start(info: &mut BiosInfo) {
     gdt::LONG_MODE_GDT.load();
     enter_long_mode_and_jump_to_stage_4(info);
 
-    loop {}
+    loop {
+        hlt();
+    }
 }
 
 #[no_mangle]

bios/stage-4/src/main.rs

@@ -227,7 +227,7 @@ fn detect_rsdp() -> Option<PhysAddr> {
     }
 }
 
-#[cfg(all(not(test), target_os = "none"))]
+#[cfg(target_os = "none")]
 #[panic_handler]
 fn panic(info: &core::panic::PanicInfo) -> ! {
     unsafe {

common/src/legacy_memory_region.rs

@@ -11,6 +11,10 @@ pub trait LegacyMemoryRegion: Copy + core::fmt::Debug {
     fn start(&self) -> PhysAddr;
     /// Returns the size of the region in bytes.
     fn len(&self) -> u64;
+    /// Returns whether this region is empty.
+    fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
     /// Returns the type of the region, e.g. whether it is usable or reserved.
     fn kind(&self) -> MemoryRegionKind;
 
@@ -81,6 +85,11 @@ where
         self.original.len()
     }
 
+    /// Returns whether this memory map is empty.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
     /// Returns the largest detected physical memory address.
     ///
     /// Useful for creating a mapping for all physical memory.

common/src/logger.rs

@@ -51,7 +51,7 @@ fn get_char_raster(c: char) -> RasterizedChar {
             font_constants::CHAR_RASTER_HEIGHT,
         )
     }
-    get(c).unwrap_or(get(BACKUP_CHAR).expect("Should get raster of backup char."))
+    get(c).unwrap_or_else(|| get(BACKUP_CHAR).expect("Should get raster of backup char."))
 }
 
 impl LockedLogger {
@@ -62,6 +62,7 @@ impl LockedLogger {
 
     /// Force-unlocks the logger to prevent a deadlock.
     ///
+    /// ## Safety
     /// This method is not memory safe and should be only used when absolutely necessary.
     pub unsafe fn force_unlock(&self) {
         unsafe { self.0.force_unlock() };

tests/lto.rs

@@ -5,7 +5,7 @@ use bootloader_test_runner::run_test_kernel;
 #[test]
 fn basic_boot() {
     // build test kernel manually to force-enable link-time optimization
-    let mut cmd = Command::new(std::env::var("CARGO").unwrap_or("cargo".into()));
+    let mut cmd = Command::new(std::env::var("CARGO").unwrap_or_else(|_| "cargo".into()));
     cmd.arg("build");
     cmd.arg("-p").arg("test_kernel_lto");
     cmd.arg("--target").arg("x86_64-unknown-none");