fix pi-lens warnings: unwraps, shell SC2046, dup code (fmtbuf/scripts/hexdump/cat/ahci/pci)

- memory.rs: self-test Layout::from_size_align no longer panics — the
  test fails cleanly on an invalid layout
- fat.rs: v() no longer unwraps the active-volume slot — invariant
  violation logs + halts instead of panicking mid-disk-io
- strbuf: shared FmtBuf replaces the duplicated PanicBuf/FmtBuf
  (main.rs + sched.rs)
- test-disk.sh: SC2046 — conditional --fresh arg no longer relies on
  word splitting
- scripts: boot.sh/boot-image.sh share lib-boot-args.sh (dup args loop)
- shell: cat/hexdump stdin pairs unified with Option<&str> marker;
  hexdump format_row folded into format_partial
- ahci: read/write_sectors unified behind dma_sectors
- pci: config_read/write share config_addr

1 files changed, 2 insertions, 16 deletions

diff --git a/rsnix/src/sched.rs b/rsnix/src/sched.rs
index 4b10503..6ffa745 100644
--- a/rsnix/src/sched.rs
+++ b/rsnix/src/sched.rs
@@ -372,7 +372,7 @@ pub fn page_fault(cr2: u64, frame_ptr: usize) -> usize {
     let rip = unsafe { (frame_ptr as *const IntFrame).read().rip };
     let mut buf = [0u8; 96];
     let n = {
-        let mut f = FmtBuf { b: &mut buf, n: 0 };
+        let mut f = crate::strbuf::FmtBuf::new(&mut buf);
         let _ = fmt::write(
             &mut f,
             core::format_args!(
@@ -386,7 +386,7 @@ pub fn page_fault(cr2: u64, frame_ptr: usize) -> usize {
                 rip
             ),
         );
-        f.n
+        f.len()
     };
     abort_current(core::str::from_utf8(&buf[..n]).unwrap_or("task fault"))
 }
@@ -528,17 +528,3 @@ fn idle_main() {
         }
     }
 }
-
-struct FmtBuf<'a> {
-    b: &'a mut [u8],
-    n: usize,
-}
-
-impl fmt::Write for FmtBuf<'_> {
-    fn write_str(&mut self, s: &str) -> fmt::Result {
-        let m = s.len().min(self.b.len() - self.n);
-        self.b[self.n..self.n + m].copy_from_slice(&s.as_bytes()[..m]);
-        self.n += m;
-        Ok(())
-    }
-}