Our Red Bear patches had reverted the userspace fd allocation refactor
(commit 372b200f) in exec.rs. This caused FD tracking mismatches
between the userspace FILETABLE and the kernel fd table, resulting in
EEXIST errors and fork failures.
Restored the upstream version which correctly uses redox_rt::sys::*
functions (openat, dup, sys_call_ro) that go through the FILETABLE,
and openat_into_upper for pre-init FD allocation. Also includes the
filetable_binary_fd setup and same_process flag in ExtraInfo.
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.
This can be done using rmdir /scheme/my_scheme. Scheme implementations
do not yet exit when all fds are closed, but you can now kill the
service and restart it after you removed its scheme.
This sets PATH, LD_LIBRARY_PATH and runs init scripts for the new root.
In the future this could replace the entire set of services that should
run, restarting any services for which a newer executable is available
in the new root and stopping any services which don't exist in the new
root. This behavior could also be useful for soft-reboots in the future
to handle updates without rebooting the entire system.
Red Bear OS