fix(clippy): make clippy = host libs + riscv programs (shared PROGRAMS); libkos alloc spinlock (was unlocked across threads); keystore Account; gpu Rect; factory Entry; Default impls, let-chains, div_ceil, iter loops

Makefile

@@ -28,8 +28,11 @@ check:
 fmt:
 	cargo fmt --all -- --check
 
+# Libraries on the host; programs (no_std, they link only for RISC-V) for
+# their target, as `build` builds them. The adapter is `kernel-clippy`'s.
 clippy:
-	cargo clippy --workspace -- -D warnings
+	cargo clippy --workspace --exclude adapter-riscv --lib -- -D warnings
+	cargo clippy --target $(RISCV_TARGET) --release $(PROGRAMS) -- -D warnings
 
 test:
 	cargo test --workspace
@@ -48,14 +51,15 @@ kani-kernel:
 
 kani: kani-types kani-domain kani-kernel
 
-# Programs first: the kernel image packs init and storage (see the
+PROGRAMS = -p init -p echo -p sleep -p snake \
-# adapter's build.rs).
-build:
-	cargo build --target $(RISCV_TARGET) --release \
-		-p init -p echo -p sleep -p snake \
 	-p display-qemu -p input-qemu -p storage-qemu \
 	-p log-server -p permission-manager -p session-server -p smptest -p spawntest -p hello \
 	-p terminal-server -p shell -p cat -p ls -p counter -p gatekeeper
+
+# Programs first: the kernel image packs init and storage (see the
+# adapter's build.rs).
+build:
+	cargo build --target $(RISCV_TARGET) --release $(PROGRAMS)
 	cargo build --target $(RISCV_TARGET) --release -p adapter-riscv
 
 # The keystore holds the owner's sealed keys: made once, never rebuilt.

crates/apps/snake/src/game.rs

@@ -44,6 +44,12 @@ pub struct Snake {
     rng_state: u32,
 }
 
+impl Default for Snake {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl Snake {
     pub fn new() -> Self {
         let start = Position { x: GRID_WIDTH / 2, y: GRID_HEIGHT / 2 };

crates/apps/snake/src/main.rs

@@ -61,8 +61,7 @@ fn main() {
 
     loop {
         let count = renderer::render(&snake, &mut commands);
-        for i in 0..count {
+        for cmd in &commands[..count] {
-            let cmd = &commands[i];
             draw_rect(cmd.x, cmd.y, cmd.w, cmd.h, cmd.color);
         }
         flush();

crates/drivers/framebuffer/virtio/src/lib.rs

@@ -148,7 +148,8 @@ impl Framebuffer for VirtioFramebuffer {
     fn flush(&mut self) {
         let w = self.width.raw() as u32;
         let h = self.height.raw() as u32;
-        gpu::transfer_to_host(&self.mmio, &self.queue, &self.dma, RESOURCE_ID, 0, 0, w, h);
+        let whole = gpu::Rect { x: 0, y: 0, w, h };
-        gpu::resource_flush(&self.mmio, &self.queue, &self.dma, RESOURCE_ID, 0, 0, w, h);
+        gpu::transfer_to_host(&self.mmio, &self.queue, &self.dma, RESOURCE_ID, whole);
+        gpu::resource_flush(&self.mmio, &self.queue, &self.dma, RESOURCE_ID, whole);
     }
 }

crates/hw-virtio/src/gpu.rs

@@ -56,18 +56,27 @@ pub fn set_scanout(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaAddr
     submit_cmd(mmio, queue, dma, 48)
 }
 
-pub fn transfer_to_host(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaAddrs, resource_id: u32, x: u32, y: u32, w: u32, h: u32) -> bool {
+/// A rectangle of a resource, in pixels.
+#[derive(Clone, Copy, Debug)]
+pub struct Rect {
+    pub x: u32,
+    pub y: u32,
+    pub w: u32,
+    pub h: u32,
+}
+
+pub fn transfer_to_host(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaAddrs, resource_id: u32, rect: Rect) -> bool {
     write_cmd_header(&dma.cmd, 0x0105);
-    put_rect(&dma.cmd, x, y, w, h);
+    put_rect(&dma.cmd, rect);
     // Offset into the resource's memory, then the resource id.
     dma.cmd.write(BODY + 16, 0u64);
     dma.cmd.write(BODY + 24, resource_id);
     submit_cmd(mmio, queue, dma, 56)
 }
 
-pub fn resource_flush(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaAddrs, resource_id: u32, x: u32, y: u32, w: u32, h: u32) -> bool {
+pub fn resource_flush(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaAddrs, resource_id: u32, rect: Rect) -> bool {
     write_cmd_header(&dma.cmd, 0x0104);
-    put_rect(&dma.cmd, x, y, w, h);
+    put_rect(&dma.cmd, rect);
     dma.cmd.write(BODY + 16, resource_id);
     submit_cmd(mmio, queue, dma, 48)
 }
@@ -77,11 +86,11 @@ fn write_cmd_header(cmd: &Window, cmd_type: u32) {
     cmd.write(TYPE, cmd_type);
 }
 
-fn put_rect(cmd: &Window, x: u32, y: u32, w: u32, h: u32) {
+fn put_rect(cmd: &Window, r: Rect) {
-    cmd.write(RECT_X, x);
+    cmd.write(RECT_X, r.x);
-    cmd.write(RECT_Y, y);
+    cmd.write(RECT_Y, r.y);
-    cmd.write(RECT_W, w);
+    cmd.write(RECT_W, r.w);
-    cmd.write(RECT_H, h);
+    cmd.write(RECT_H, r.h);
 }
 
 pub fn get_display_info(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaAddrs) -> Option<(u32, u32)> {

crates/init/src/factory.rs

@@ -43,16 +43,30 @@ impl Path {
     }
 }
 
-/// Up to `BATCH` entries of `dir`: names and whether each is a folder.
+/// One thing in a folder.
-fn entries(fs: &mut Storage, dir: &Path) -> Option<([([u8; NAME], usize, bool); BATCH], usize)> {
+#[derive(Clone, Copy)]
-    let mut out = [([0u8; NAME], 0, false); BATCH];
+struct Entry {
+    name: [u8; NAME],
+    len: usize,
+    is_dir: bool,
+}
+
+impl Entry {
+    fn name(&self) -> &[u8] {
+        &self.name[..self.len]
+    }
+}
+
+/// Up to `BATCH` entries of `dir`.
+fn entries(fs: &mut Storage, dir: &Path) -> Option<([Entry; BATCH], usize)> {
+    let mut out = [Entry { name: [0; NAME], len: 0, is_dir: false }; BATCH];
     let mut n = 0;
     fs.list_dir(dir.as_bytes(), |e| {
         let name = e.name();
         if name != b"." && name != b".." && n < BATCH {
-            out[n].0[..name.len()].copy_from_slice(name);
+            out[n].name[..name.len()].copy_from_slice(name);
-            out[n].1 = name.len();
+            out[n].len = name.len();
-            out[n].2 = e.is_dir;
+            out[n].is_dir = e.is_dir;
             n += 1;
         }
     })
@@ -83,9 +97,9 @@ fn copy_tree(fs: &mut Storage, from: &Path, to: &Path, buf: &mut [u8]) -> Result
         // Nothing shipped for this area.
         None => return Ok(()),
     };
-    for (name, len, is_dir) in &list[..n] {
+    for entry in &list[..n] {
-        let (src, dst) = (from.join(&name[..*len]).ok_or("path too long")?, to.join(&name[..*len]).ok_or("path too long")?);
+        let (src, dst) = (from.join(entry.name()).ok_or("path too long")?, to.join(entry.name()).ok_or("path too long")?);
-        if *is_dir {
+        if entry.is_dir {
             fs.mkdir(dst.as_bytes()).map_err(|_| "cannot make a folder")?;
             copy_tree(fs, &src, &dst, buf)?;
         } else {

crates/init/src/load.rs

@@ -54,7 +54,7 @@ pub(crate) fn load_binary(
         let page_start = segment.vaddr & !0xFFF;
         let offset_in_page = segment.vaddr & 0xFFF;
         let total_size = offset_in_page + segment.mem_size;
-        let seg_pages = (total_size + PAGE_SIZE - 1) / PAGE_SIZE;
+        let seg_pages = total_size.div_ceil(PAGE_SIZE);
 
         let page_count = PageCount::new(u16::try_from(seg_pages).ok()?)?;
         let local = libkos::window::request(page_count)?;

crates/keystore/src/lib.rs

@@ -21,6 +21,7 @@ mod user;
 mod tests;
 
 pub use record::{
+    Account,
     Copies, Entry, KdfParams, Outcome, RECORD_SIZE, Record, Refused, SLOTS, Session, State,
 };
 pub use user::{Name, Role, User, UserId};

crates/keystore/src/record.rs

@@ -154,6 +154,15 @@ fn parse_user(role: u8, id: &[u8], name: &[u8]) -> Option<User> {
     })
 }
 
+/// A user about to be added: who, and the passcodes that will open their
+/// slot (and, if given, their duress slot).
+pub struct Account<'a> {
+    pub name: Name,
+    pub role: Role,
+    pub passcode: &'a [u8],
+    pub duress: Option<&'a [u8]>,
+}
+
 impl Record {
     fn name_tag(&self, name: &Name) -> [u8; NAME_TAG] {
         let mut m = <Blake2sMac256 as KeyInit>::new_from_slice(&self.pepper)
@@ -273,7 +282,7 @@ impl Record {
             admin: Some(admin),
         };
         let (record, user) = first
-            .add_user(&owner, name, Role::Owner, passcode, duress, memory, rng)
+            .add_user(&owner, Account { name, role: Role::Owner, passcode, duress }, memory, rng)
             .ok()?;
         let session = record.unlock(name.as_bytes(), passcode, memory);
         let _ = user;
@@ -371,16 +380,8 @@ impl Record {
     }
 
     /// An owner adds a user; the new record and the user.
-    pub fn add_user(
+    pub fn add_user(&self, by: &Session, account: Account, memory: &mut [Block], rng: &mut impl Random) -> Result<(Self, User), Refused> {
-        &self,
+        let Account { name, role, passcode, duress } = account;
-        by: &Session,
-        name: Name,
-        role: Role,
-        passcode: &[u8],
-        duress: Option<&[u8]>,
-        memory: &mut [Block],
-        rng: &mut impl Random,
-    ) -> Result<(Self, User), Refused> {
         let admin = by.admin.clone().ok_or(Refused::NotOwner)?;
         let mut entries = self.entries(&admin).ok_or(Refused::Failed)?;
         if entries.iter().flatten().any(|e| e.user.name == name) {
@@ -467,10 +468,10 @@ impl Record {
             return Err(Refused::LastOwner);
         }
         let mut r = self.next(|_| {});
-        for i in 0..SLOTS {
+        for (entry, slot) in entries.iter_mut().zip(r.slots.iter_mut()) {
-            if entries[i].is_some_and(|e| e.user.id == gone.id) {
+            if entry.is_some_and(|e| e.user.id == gone.id) {
-                r.slots[i] = Slot(noise(rng).ok_or(Refused::Failed)?);
+                *slot = Slot(noise(rng).ok_or(Refused::Failed)?);
-                entries[i] = None;
+                *entry = None;
             }
         }
         if !r.seal_directory(&admin, &entries, rng) {

crates/keystore/src/tests.rs

@@ -79,15 +79,7 @@ fn users_have_their_own_keys_and_may_even_share_a_passcode() {
     let (r, owner) = setup(None, 2);
     let mut rng = Counter(40);
     let (r, work) = r
-        .add_user(
+        .add_user(&owner, Account { name: name("work"), role: Role::Standard, passcode: b"1234", duress: None }, &mut memory(), &mut rng)
-            &owner,
-            name("work"),
-            Role::Standard,
-            b"1234",
-            None,
-            &mut memory(),
-            &mut rng,
-        )
         .unwrap();
     let w = signed_in(&r, "work", b"1234").unwrap();
     let g = signed_in(&r, "gabriel", b"1234").unwrap();
@@ -105,15 +97,7 @@ fn users_have_their_own_keys_and_may_even_share_a_passcode() {
         "not even hidden in their slot"
     );
     assert_eq!(
-        r.add_user(
+        r.add_user(&w, Account { name: name("x"), role: Role::Standard, passcode: b"9", duress: None }, &mut memory(), &mut rng)
-            &w,
-            name("x"),
-            Role::Standard,
-            b"9",
-            None,
-            &mut memory(),
-            &mut rng
-        )
         .err(),
         Some(Refused::NotOwner)
     );
@@ -125,26 +109,10 @@ fn owners_see_and_manage_the_users() {
     let (r, owner) = setup(Some(b"0000"), 3);
     let mut rng = Counter(50);
     let (r, _) = r
-        .add_user(
+        .add_user(&owner, Account { name: name("work"), role: Role::Standard, passcode: b"5678", duress: Some(b"8765") }, &mut memory(), &mut rng)
-            &owner,
-            name("work"),
-            Role::Standard,
-            b"5678",
-            Some(b"8765"),
-            &mut memory(),
-            &mut rng,
-        )
         .unwrap();
     let (r, second) = r
-        .add_user(
+        .add_user(&owner, Account { name: name("anna"), role: Role::Owner, passcode: b"4321", duress: None }, &mut memory(), &mut rng)
-            &owner,
-            name("anna"),
-            Role::Owner,
-            b"4321",
-            None,
-            &mut memory(),
-            &mut rng,
-        )
         .unwrap();
     let names: Vec<_> = r
         .users(&owner)
@@ -155,15 +123,7 @@ fn owners_see_and_manage_the_users() {
         .collect();
     assert_eq!(names.len(), 3, "duress slots are not listed: {names:?}");
     assert_eq!(
-        r.add_user(
+        r.add_user(&owner, Account { name: name("work"), role: Role::Standard, passcode: b"x", duress: None }, &mut memory(), &mut rng)
-            &owner,
-            name("work"),
-            Role::Standard,
-            b"x",
-            None,
-            &mut memory(),
-            &mut rng
-        )
         .err(),
         Some(Refused::NameTaken)
     );
@@ -205,15 +165,7 @@ fn slots_run_out() {
     let mut added = 0;
     for i in 0..SLOTS {
         let n = std::format!("u{i}");
-        match r.add_user(
+        match r.add_user(&owner, Account { name: name(&n), role: Role::Standard, passcode: b"pass", duress: None }, &mut memory(), &mut rng) {
-            &owner,
-            name(&n),
-            Role::Standard,
-            b"pass",
-            None,
-            &mut memory(),
-            &mut rng,
-        ) {
             Ok((next, _)) => {
                 r = next;
                 added += 1;

crates/libkos/src/alloc_impl.rs

@@ -1,6 +1,8 @@
 use core::alloc::{GlobalAlloc, Layout};
 use core::cell::UnsafeCell;
+use core::ops::{Deref, DerefMut};
 use core::ptr;
+use core::sync::atomic::{AtomicBool, Ordering};
 
 const PAGE_SIZE: usize = 4096;
 
@@ -10,6 +12,8 @@ struct FreeBlock {
 }
 
 pub struct KosAllocator {
+    /// A program's threads share the heap: one at a time in the free list.
+    locked: AtomicBool,
     inner: UnsafeCell<AllocatorInner>,
 }
 
@@ -24,12 +28,45 @@ unsafe impl Sync for KosAllocator {}
 impl KosAllocator {
     pub const fn new() -> Self {
         Self {
+            locked: AtomicBool::new(false),
             inner: UnsafeCell::new(AllocatorInner { free_list: ptr::null_mut() }),
         }
     }
 
-    fn inner_mut(&self) -> &mut AllocatorInner {
+    fn lock(&self) -> Locked<'_> {
-        unsafe { &mut *self.inner.get() }
+        while self.locked.compare_exchange_weak(false, true, Ordering::Acquire, Ordering::Relaxed).is_err() {
+            core::hint::spin_loop();
+        }
+        Locked(self)
+    }
+}
+
+impl Default for KosAllocator {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+/// The free list, held until dropped.
+struct Locked<'a>(&'a KosAllocator);
+
+impl Deref for Locked<'_> {
+    type Target = AllocatorInner;
+    fn deref(&self) -> &AllocatorInner {
+        // Only one `Locked` exists at a time.
+        unsafe { &*self.0.inner.get() }
+    }
+}
+
+impl DerefMut for Locked<'_> {
+    fn deref_mut(&mut self) -> &mut AllocatorInner {
+        unsafe { &mut *self.0.inner.get() }
+    }
+}
+
+impl Drop for Locked<'_> {
+    fn drop(&mut self) {
+        self.0.locked.store(false, Ordering::Release);
     }
 }
 
@@ -103,7 +140,7 @@ impl AllocatorInner {
 
 unsafe impl GlobalAlloc for KosAllocator {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        let inner = self.inner_mut();
+        let mut inner = self.lock();
         let size = layout.size().max(core::mem::size_of::<FreeBlock>());
         let align = layout.align();
 
@@ -113,7 +150,7 @@ unsafe impl GlobalAlloc for KosAllocator {
         }
 
         // Alignment can cost up to `align` bytes of the block.
-        let pages_needed = (size + align + PAGE_SIZE - 1) / PAGE_SIZE;
+        let pages_needed = (size + align).div_ceil(PAGE_SIZE);
         let block = inner.request_pages(pages_needed);
         if block.is_null() {
             return ptr::null_mut();
@@ -124,7 +161,7 @@ unsafe impl GlobalAlloc for KosAllocator {
     }
 
     unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
-        let inner = self.inner_mut();
+        let mut inner = self.lock();
         let size = layout.size().max(core::mem::size_of::<FreeBlock>());
         inner.add_to_free_list(ptr, size);
     }

crates/libkos/src/syscall/process.rs

@@ -12,12 +12,17 @@ use types::time::Ticks;
 
 pub fn exit() -> ! {
     let _ = call0(SYS_EXIT);
-    loop {}
+    // The kernel does not return from an exit.
+    loop {
+        core::hint::spin_loop();
+    }
 }
 
 pub fn exit_thread() -> ! {
     let _ = call0(SYS_EXIT_THREAD);
-    loop {}
+    loop {
+        core::hint::spin_loop();
+    }
 }
 
 pub fn yield_now() {
@@ -28,7 +33,9 @@ pub fn yield_now() {
 /// call fails and this spins, since there is nothing sensible to return.
 pub fn halt(control: CapSlot) -> ! {
     let _ = raw(SYS_HALT, [control.value() as usize, 0, 0, 0, 0, 0]);
-    loop {}
+    loop {
+        yield_now();
+    }
 }
 
 pub fn get_time() -> Ticks {

crates/servers/gatekeeper/src/flow.rs

@@ -2,7 +2,7 @@
 //! randomness, and the owner (`Prompt`). No kernel, no hardware: tested on
 //! the host.
 
-use keystore::{Block, Copies, KdfParams, Key, Name, Outcome, RECORD_SIZE, Random, Record, Refused, Role, SLOTS, Session, User, UserId};
+use keystore::{Account, Block, Copies, KdfParams, Key, Name, Outcome, RECORD_SIZE, Random, Record, Refused, Role, SLOTS, Session, User, UserId};
 use zeroize::Zeroize;
 
 /// The keystore device: the record's two copies.
@@ -228,7 +228,7 @@ fn manage(ks: &mut impl Keystore, rng: &mut impl Random, prompt: &mut impl Promp
                 let (mut real, mut duress) = (Secret::new(), Secret::new());
                 ask_passcodes(prompt, &mut real, &mut duress)?;
                 let duress = (duress.len > 0).then_some(duress.as_bytes());
-                record.add_user(session, name, role, real.as_bytes(), duress, memory, rng).map(|(r, _)| r)
+                record.add_user(session, Account { name, role, passcode: real.as_bytes(), duress }, memory, rng).map(|(r, _)| r)
             }
             b"r" => {
                 let name = ask_name(prompt, "Remove whom: ")?;

crates/servers/input-server/src/adapters/mock.rs

@@ -6,6 +6,12 @@ pub struct MockInputDevice {
     tail: usize,
 }
 
+impl Default for MockInputDevice {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl MockInputDevice {
     pub fn new() -> Self {
         Self {

crates/servers/log-server/src/server.rs

@@ -18,6 +18,12 @@ pub struct LogServer<O: FnMut(&[u8]) = fn(&[u8])> {
     out: O,
 }
 
+impl Default for LogServer {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl LogServer {
     /// Text goes nowhere.
     pub fn new() -> Self {

crates/servers/storage-server/src/adapters/mock_fs.rs

@@ -44,16 +44,21 @@ impl MockFileSystem {
 
     fn find_by_name(&self, path: &[u8]) -> Option<usize> {
         for i in 0..MAX_FILES {
-            if let Some(entry) = &self.files[i] {
+            if let Some(entry) = &self.files[i]
-                if entry.name == *path {
+                && entry.name == *path {
                     return Some(i);
                 }
         }
-        }
         None
     }
 }
 
+impl Default for MockFileSystem {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl FileSystem for MockFileSystem {
     fn writable(&self) -> bool {
         !self.read_only

crates/servers/storage-server/src/filesystem.rs

@@ -39,6 +39,10 @@ impl FileName {
     pub fn len(&self) -> usize {
         self.len as usize
     }
+
+    pub fn is_empty(&self) -> bool {
+        self.len == 0
+    }
 }
 
 impl PartialEq<[u8]> for FileName {

crates/servers/storage-server/src/fs/ext4/dir.rs

@@ -37,11 +37,10 @@ pub fn find_entry<B: BlockDevice>(
                 let name_len = block_buf[pos + 6] as usize;
 
                 if rec_len == 0 { break; }
-                if entry_inode != 0 && name_len == name.len() {
+                if entry_inode != 0 && name_len == name.len()
-                    if &block_buf[pos + 8..pos + 8 + name_len] == name {
+                    && &block_buf[pos + 8..pos + 8 + name_len] == name {
                         return Some(entry_inode);
                     }
-                }
                 pos += rec_len;
             }
         }
@@ -147,8 +146,8 @@ pub fn remove_entry<B: BlockDevice>(
                 let name_len = block_buf[pos + 6] as usize;
 
                 if rec_len == 0 { break; }
-                if entry_inode != 0 && name_len == name.len() {
+                if entry_inode != 0 && name_len == name.len()
-                    if &block_buf[pos + 8..pos + 8 + name_len] == name {
+                    && &block_buf[pos + 8..pos + 8 + name_len] == name {
                         if let Some(pp) = prev_pos {
                             let prev_rec = read_u16(&block_buf, pp + 4) as usize;
                             write_u16(&mut block_buf, pp + 4, (prev_rec + rec_len) as u16);
@@ -158,7 +157,6 @@ pub fn remove_entry<B: BlockDevice>(
                         write_block(device, phys, spb, &block_buf);
                         return Some(entry_inode);
                     }
-                }
                 prev_pos = Some(pos);
                 pos += rec_len;
             }

crates/servers/storage-server/src/fs/ext4/mod.rs

@@ -131,7 +131,9 @@ impl<B: BlockDevice> FileSystem for Ext4<B> {
             done += chunk;
         }
 
-        self.open_files[handle.raw() as usize].as_mut().map(|f| f.offset += done);
+        if let Some(f) = self.open_files[handle.raw() as usize].as_mut() {
+            f.offset += done;
+        }
         Some(done)
     }
 
@@ -204,14 +206,13 @@ impl<B: BlockDevice> FileSystem for Ext4<B> {
 
     fn close(&mut self, handle: FileHandle) {
         if handle.raw() as usize >= MAX_OPEN_FILES { return; }
-        if let Some(file) = self.open_files[handle.raw() as usize].take() {
+        if let Some(file) = self.open_files[handle.raw() as usize].take()
-            if let Some(mut inode) = self.read_inode(file.inode_num) {
+            && let Some(mut inode) = self.read_inode(file.inode_num) {
                 inode.size = file.size as u64;
                 inode.block_data = file.block_data;
                 self.write_inode(file.inode_num, &inode);
             }
     }
-    }
 
     fn list_dir(&mut self, path: &[u8], entries: &mut [DirEntry]) -> Option<usize> {
         let dir_inode_num = if path.is_empty() || path == b"/" {
@@ -222,13 +223,12 @@ impl<B: BlockDevice> FileSystem for Ext4<B> {
 
         let inode = self.read_inode(dir_inode_num)?;
         let count = dir::list_entries(&mut self.device, &self.sb, &inode, entries)?;
-        for i in 0..count {
+        for entry in entries.iter_mut().take(count) {
-            if !entries[i].is_dir {
+            if !entry.is_dir {
-                let name = entries[i].name;
+                let name = entry.name;
-                if let Some(child_ino) = dir::find_entry(&mut self.device, &self.sb, &inode, name.as_bytes()) {
+                if let Some(child_ino) = dir::find_entry(&mut self.device, &self.sb, &inode, name.as_bytes())
-                    if let Some(child) = self.read_inode(child_ino) {
+                    && let Some(child) = self.read_inode(child_ino) {
-                        entries[i].size = child.size as usize;
+                        entry.size = child.size as usize;
-                    }
                     }
             }
         }
@@ -279,11 +279,10 @@ impl<B: BlockDevice> FileSystem for Ext4<B> {
             None => return false,
         };
 
-        if let Some(child_inode) = self.read_inode(child_inode_num) {
+        if let Some(child_inode) = self.read_inode(child_inode_num)
-            if child_inode.is_dir() {
+            && child_inode.is_dir() {
                 return false;
             }
-        }
 
         let parent_inode = match self.read_inode(parent_inode_num) {
             Some(i) => i,
@@ -299,12 +298,11 @@ impl<B: BlockDevice> FileSystem for Ext4<B> {
         self.clear_inode(child_inode_num);
         self.free_inode(child_inode_num);
         for slot in self.open_files.iter_mut() {
-            if let Some(f) = slot {
+            if let Some(f) = slot
-                if f.inode_num == child_inode_num {
+                && f.inode_num == child_inode_num {
                     *slot = None;
                 }
         }
-        }
         true
     }
 

crates/servers/storage-server/src/grants.rs

@@ -102,3 +102,9 @@ impl Grants {
         }
     }
 }
+
+impl Default for Grants {
+    fn default() -> Self {
+        Self::new()
+    }
+}