libconfig: wrap FS in OnceLock

Cargo.lock

@@ -104,6 +104,7 @@ dependencies = [
  "core_io",
  "fatfs",
  "libboard_zynq",
+ "libcortex_a9",
  "log",
 ]
 

libconfig/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2018"
 [dependencies]
 libboard_zynq = { path = "../libboard_zynq" }
 log = "0.4"
+libcortex_a9 = { path = "../libcortex_a9" }
 
 [dependencies.core_io]
 git = "https://git.m-labs.hk/M-Labs/rs-core_io.git"

libconfig/src/lib.rs

@@ -7,6 +7,7 @@ use core::fmt;
 
 use core_io::{self as io, BufRead, BufReader, Read, Seek, SeekFrom, Write};
 use libboard_zynq::sdio;
+use libcortex_a9::once_lock::OnceLock;
 
 pub mod bootgen;
 pub mod net_settings;
@@ -66,12 +67,7 @@ fn parse_config(key: &str, buffer: &mut Vec<u8>, file: fatfs::File<sd_reader::Sd
 }
 
 type FileSystem = fatfs::FileSystem<sd_reader::SdReader>;
-static mut FS: Option<FileSystem> = None;
-
-#[allow(static_mut_refs)]
-pub fn get_filesystem() -> &'static Option<FileSystem> {
-    unsafe { &FS }
-}
+pub static FS: OnceLock<FileSystem> = OnceLock::new();
 
 const NEWLINE: &[u8] = b"\n";
 
@@ -85,18 +81,16 @@ pub fn init() -> Result<()> {
 
     let fs = reader.mount_fatfs(sd_reader::PartitionEntry::Entry1)?;
 
-    unsafe {
-        FS = Some(fs);
-    }
+    from_fs(fs);
     Ok(())
 }
 
-pub fn from_fs(fs: Option<FileSystem>) {
-    unsafe { FS = fs }
+pub fn from_fs(fs: FileSystem) {
+    FS.set(fs).expect("filesystem can only be initialized once");
 }
 
 pub fn read(key: &str) -> Result<Vec<u8>> {
-    if let Some(fs) = get_filesystem() {
+    if let Some(fs) = FS.get() {
         let root_dir = fs.root_dir();
         let mut buffer: Vec<u8> = Vec::new();
         match root_dir.open_file(&["/CONFIG/", key, ".BIN"].concat()) {
@@ -117,7 +111,7 @@ pub fn read_str(key: &str) -> Result<String> {
 }
 
 pub fn remove(key: &str) -> Result<()> {
-    if let Some(fs) = get_filesystem() {
+    if let Some(fs) = FS.get() {
         let root_dir = fs.root_dir();
         match root_dir.remove(&["/CONFIG/", key, ".BIN"].concat()) {
             Ok(()) => Ok(()),
@@ -147,10 +141,10 @@ pub fn remove(key: &str) -> Result<()> {
 }
 
 pub fn write(key: &str, value: Vec<u8>) -> Result<()> {
-    if get_filesystem().is_none() {
+    if FS.get().is_none() {
         return Err(Error::NoConfig);
     }
-    let fs = get_filesystem().as_ref().unwrap();
+    let fs = FS.get().unwrap();
     let root_dir = fs.root_dir();
     let is_str = value.len() <= 100 && value.is_ascii() && !value.contains(&b'\n');
     if key == "boot" {

szl/src/main.rs

@@ -87,21 +87,24 @@ pub fn main_core0() {
     ram::init_alloc_core0();
 
     let sdio0 = sdio::Sdio::sdio0(true);
-    let fs = if sdio0.is_card_inserted() {
+    let mut bootgen_file = if sdio0.is_card_inserted() {
         info!("Card inserted. Mounting file system.");
         let sd = sdio::sd_card::SdCard::from_sdio(sdio0).unwrap();
         let reader = sd_reader::SdReader::new(sd);
-        reader.mount_fatfs(sd_reader::PartitionEntry::Entry1).ok()
+        reader
+            .mount_fatfs(sd_reader::PartitionEntry::Entry1)
+            .and_then(|fs| {
+                libconfig::from_fs(fs);
+                let fs_ref = libconfig::FS.get().unwrap();
+                let root_dir = fs_ref.root_dir();
+                root_dir.open_file("/BOOT.BIN")
+            })
+            .ok()
     } else {
         info!("No SD card inserted.");
         None
     };
 
-    libconfig::from_fs(fs);
-    let fs_ref = libconfig::get_filesystem().as_ref();
-    let root_dir = fs_ref.map(|fs| fs.root_dir());
-    let mut bootgen_file = root_dir.and_then(|root_dir| root_dir.open_file("/BOOT.BIN").ok());
-
     let max_len = (&raw const __runtime_end).addr() - (&raw const __runtime_start).addr();
     match slcr::RegisterBlock::unlocked(|slcr| slcr.boot_mode.read().boot_mode_pins()) {
         slcr::BootModePins::Jtag => netboot::netboot(&mut bootgen_file, (&raw mut __runtime_start).cast(), max_len),