feat(filesystem): add init in memory fatfs

awkernel_lib/src/allocator.rs

@@ -0,0 +1,5 @@
+#[cfg(feature = "std")]
+pub use std::alloc::System;
+
+#[cfg(not(feature = "std"))]
+pub use super::heap::TALLOC as System;

awkernel_lib/src/file/fatfs.rs

@@ -6,3 +6,73 @@ pub mod file;
 pub mod fs;
 pub mod table;
 pub mod time;
+
+use crate::{
+    allocator::System,
+    file::{
+        fatfs::{
+            fs::{format_volume, FileSystem, FormatVolumeOptions, FsOptions, LossyOemCpConverter},
+            time::NullTimeProvider,
+        },
+        memfs::InMemoryDisk,
+    },
+    paging::PAGESIZE,
+    sync::rwlock::RwLock,
+};
+
+use alloc::{format, string::String, sync::Arc, vec::Vec};
+use core::alloc::{GlobalAlloc, Layout};
+
+pub const MEMORY_FILESYSTEM_SIZE: usize = 1024 * 1024;
+
+static FAT_FS_INSTANCE: RwLock<
+    Option<Arc<FileSystem<InMemoryDisk, NullTimeProvider, LossyOemCpConverter>>>,
+> = RwLock::new(None);
+
+pub fn init_memory_fatfs() -> Result<(), String> {
+    let mut fs_guard = FAT_FS_INSTANCE.write();
+    if fs_guard.is_some() {
+        return Err("FAT filesystem has already been initialized.".into());
+    }
+
+    let disk_layout = Layout::from_size_align(MEMORY_FILESYSTEM_SIZE, PAGESIZE)
+        .map_err(|_| "Invalid layout for memory filesystem allocation.")?;
+
+    let raw_disk_memory = unsafe { System.alloc(disk_layout) };
+    if raw_disk_memory.is_null() {
+        return Err("Failed to allocate memory for the in-memory disk.".into());
+    }
+
+    let disk_data = unsafe {
+        Vec::from_raw_parts(
+            raw_disk_memory,
+            MEMORY_FILESYSTEM_SIZE,
+            MEMORY_FILESYSTEM_SIZE,
+        )
+    };
+
+    let mut in_memory_disk = InMemoryDisk::new(disk_data, 0);
+
+    if let Err(e) = format_volume(&mut in_memory_disk, FormatVolumeOptions::new()) {
+        return Err(format!("Failed to format FAT volume: {e:?}"));
+    }
+
+    let file_system = match FileSystem::new(in_memory_disk, FsOptions::new()) {
+        Ok(fs) => fs,
+        Err(e) => {
+            return Err(format!("Failed to create FileSystem instance: {e:?}"));
+        }
+    };
+
+    *fs_guard = Some(Arc::new(file_system));
+
+    Ok(())
+}
+
+pub fn get_memory_fatfs() -> Arc<FileSystem<InMemoryDisk, NullTimeProvider, LossyOemCpConverter>> {
+    let fs_guard = FAT_FS_INSTANCE.read();
+
+    (*fs_guard)
+        .clone()
+        .expect("FAT filesystem has not been initialized. Call init_fatfs() first.")
+}

awkernel_lib/src/lib.rs

@@ -8,6 +8,7 @@ use core::{cell::Cell, marker::PhantomData};
 use alloc::rc::Rc;
 
 pub mod addr;
+pub mod allocator;
 pub mod arch;
 pub mod config;
 pub mod console;