feat(storage): ext4-only disk via mkfs.ext4 -d; drop FAT16; feature-gated mount (ro on unknown ro_compat); ext4 read spans blocks, delete clears inode, mkdir counts dir; virtio-blk writes; test-qemu e2fsck gate

crates/apps/spawntest/src/main.rs

@@ -12,9 +12,15 @@ use libkos::syscall;
 use types::bounded::CapSlot;
 use types::budget::Limits;
 
-/// Where init put them (see init's manifest: spawn endpoint, then control).
-const INIT: CapSlot = CapSlot::const_new(0);
-const CONTROL: CapSlot = CapSlot::const_new(1);
+/// Where init put them (see init's manifest: `uses`, the spawn endpoint,
+/// then control).
+const STORAGE: CapSlot = CapSlot::const_new(0);
+const INIT: CapSlot = CapSlot::const_new(1);
+const CONTROL: CapSlot = CapSlot::const_new(2);
+/// Where storage's buffer is mapped.
+const STORAGE_BUF_VA: usize = 0x0180_0000;
+/// Read back from the disk image by scripts/test-qemu.sh.
+const NOTE: &[u8] = b"written by k-os on ext4\n";
 
 /// Over half the allowance (128 pages), so a second one fits only after
 /// the first has died and its limits came back.
@@ -31,7 +37,28 @@ fn run_hello(died: CapSlot) -> Result<(), &'static str> {
     Ok(())
 }
 
+/// A file written through storage, which the host then checks with e2fsck.
+fn write_a_file() -> Result<(), &'static str> {
+    let mut fs = libkos::fs::Storage::attach(STORAGE, STORAGE_BUF_VA).map_err(|_| "cannot attach to storage")?;
+    let h = fs.create(b"selftest.txt").map_err(|_| "cannot create a file")?;
+    if fs.write(h, NOTE) != Ok(NOTE.len()) {
+        return Err("short write");
+    }
+    fs.close(h).map_err(|_| "close failed")?;
+    let h = fs.open(b"selftest.txt").map_err(|_| "cannot reopen the file")?;
+    let mut back = [0u8; 64];
+    let n = fs.read(h, &mut back).map_err(|_| "read failed")?;
+    fs.close(h).map_err(|_| "close failed")?;
+    if &back[..n] != NOTE {
+        return Err("read back something else");
+    }
+    Ok(())
+}
+
 fn check() -> Result<(), &'static str> {
+    write_a_file()?;
+    libkos::println!("spawntest: a file written to ext4 reads back: ok");
+
     let died = syscall::create_notification().map_err(|_| "no notification")?;
     run_hello(died)?;
     libkos::println!("spawntest: spawned program runs and its death is heard: ok");