From aedc416f0c96fdfdc5941b5d5104a8ad78744df4 Mon Sep 17 00:00:00 2001
From: Red Bear OS <build@redbearos.org>
Date: Sat, 11 Jul 2026 17:02:37 +0300
Subject: [PATCH] bootstrap: fix FD allocation to match upstream userspace fd
 model

The bootstrap's start.rs used libredox::call::openat which resolved to
the bootstrap's own redox_openat_v1 in initfs.rs, calling syscall::openat
(SYS_OPENAT). This let the kernel allocate POSIX FDs 0,1,2 for
stdin/stdout/stderr, but the userspace FILETABLE was never updated.

Later, exec.rs called auth.dup(b'cur-context') via redox_rt::sys::dup,
which asked the empty FILETABLE for a free slot (returning 0), then
passed it to SYS_DUP_INTO. The kernel rejected it with EEXIST because
posix_fdtbl[0] was already occupied by stdin.

Fix: use syscall::openat_into to directly specify FD slots 0,1,2 in
start.rs, and use syscall::dup_into with a computed FD index for
cur-context in exec.rs. Both bypass the FILETABLE, which is only
populated later by redox_rt::initialize_freestanding.
---
 bootstrap/src/exec.rs  |  6 ++++--
 bootstrap/src/start.rs | 21 +++------------------
 2 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/bootstrap/src/exec.rs b/bootstrap/src/exec.rs
index 84931075e0..ab64c0be03 100644
--- a/bootstrap/src/exec.rs
+++ b/bootstrap/src/exec.rs
@@ -53,6 +53,8 @@ pub fn main() -> ! {
         FdGuard::new(*(base_ptr as *const usize))
     };
 
+    let cur_context_idx = scheme_creation_cap.as_raw_fd() + 1;
+
     let mut kernel_schemes = KernelSchemeMap::new(kernel_scheme_infos);
 
     let auth = kernel_schemes
@@ -60,8 +62,8 @@ pub fn main() -> ! {
         .remove(&GlobalSchemes::Proc)
         .expect("failed to get proc fd");
 
-    let this_thr_fd = auth
-        .dup(b"cur-context")
+    let this_thr_fd = syscall::dup_into(auth.as_raw_fd(), cur_context_idx, b"cur-context")
+        .map(FdGuard::new)
         .expect("failed to open open_via_dup")
         .to_upper()
         .unwrap();
diff --git a/bootstrap/src/start.rs b/bootstrap/src/start.rs
index e551071448..e51cc8d392 100644
--- a/bootstrap/src/start.rs
+++ b/bootstrap/src/start.rs
@@ -35,10 +35,6 @@ mod offsets {
     }
 }
 
-fn dbg(msg: &[u8]) {
-    let _ = libredox::call::write(1, msg);
-}
-
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn start() -> ! {
     let (text_start, text_end) = offsets::text();
@@ -46,18 +42,14 @@ pub unsafe extern "C" fn start() -> ! {
     let (data_start, data_end) = offsets::data_and_bss();
 
     let debug_fd = syscall::UPPER_FDTBL_TAG + syscall::data::GlobalSchemes::Debug as usize;
-    let _ = libredox::call::openat(debug_fd, "", syscall::O_RDONLY as i32, 0);
-    let _ = libredox::call::openat(debug_fd, "", syscall::O_WRONLY as i32, 0);
-    let _ = libredox::call::openat(debug_fd, "", syscall::O_WRONLY as i32, 0);
-
-    dbg(b"BS:0\n");
+    let _ = syscall::openat_into(debug_fd, 0, "", syscall::O_RDONLY, 0);
+    let _ = syscall::openat_into(debug_fd, 1, "", syscall::O_WRONLY, 0);
+    let _ = syscall::openat_into(debug_fd, 2, "", syscall::O_WRONLY, 0);
 
     unsafe {
         let _ = syscall::mprotect(4096, 4096, MapFlags::PROT_READ | MapFlags::MAP_PRIVATE)
             .expect("mprotect failed for initfs header page");
 
-        dbg(b"BS:1\n");
-
         let _ = syscall::mprotect(
             text_start,
             text_end - text_start,
@@ -65,8 +57,6 @@ pub unsafe extern "C" fn start() -> ! {
         )
         .expect("mprotect failed for .text");
 
-        dbg(b"BS:2\n");
-
         let _ = syscall::mprotect(
             rodata_start,
             rodata_end - rodata_start,
@@ -74,8 +64,6 @@ pub unsafe extern "C" fn start() -> ! {
         )
         .expect("mprotect failed for .rodata");
 
-        dbg(b"BS:3\n");
-
         let _ = syscall::mprotect(
             data_start,
             data_end - data_start,
@@ -83,8 +71,6 @@ pub unsafe extern "C" fn start() -> ! {
         )
         .expect("mprotect failed for .data/.bss");
 
-        dbg(b"BS:4\n");
-
         let _ = syscall::mprotect(
             data_end,
             crate::arch::STACK_START - data_end,
@@ -93,6 +79,5 @@ pub unsafe extern "C" fn start() -> ! {
         .expect("mprotect failed for rest of memory");
     }
 
-    dbg(b"BS:5\n");
     crate::exec::main();
 }