nexoniarz/SchOS
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Job control, function keys, and real sleeps

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- SIGSTOP/SIGTSTP/SIGTTIN/SIGTTOU stop, SIGCONT resumes; the parent gets
  SIGCHLD and wait4 reports WUNTRACED/WCONTINUED; ps shows T. Ctrl-Z works,
  and mc no longer hangs waiting for its subshell to stop.
- Blocking reads (console, pty, pipe) and sleeps take a pending stop and
  carry on after SIGCONT; a caught signal without SA_RESTART ends them
  with EINTR.
- nanosleep reads tv_nsec (sleep 0.5 used to return at once), writes the
  remainder, and clock_nanosleep understands TIMER_ABSTIME.
- rt_sigaction uses the k_sigaction layout for Linux-ABI processes: the old
  action's restorer was written 112 bytes past the caller's struct. Flags
  are kept; SIGKILL and SIGSTOP cannot be caught.
- F1..F12 reach programs, as the Linux console sends them (PS/2, USB, I2C).
- TIOCLINUX subcode 6 answers "no modifiers" instead of echoing the 6 back.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
This commit is contained in:
Nexoniarz 2026-10-25 02:37:45 +01:00
commit 2372806862
13 changed files with 366 additions and 42 deletions
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54
kernel/sys/sys_sig.c
View file

@ -79,13 +79,18 @@ sys_sigwait(void)
return 0;
}
// musl's struct sigaction (musl 1.2.5 signal.h) for this target:
// sa_handler (8 bytes) at offset 0, then a 128-byte sigset_t (musl uses
// 128/sizeof(long) = 16 longs regardless of NSIG), sa_flags (4 bytes) +
// padding, then sa_restorer (8 bytes) at offset 144. We only care about
// those two 8-byte fields.
// The native musl hands over its own struct sigaction (musl 1.2.5 signal.h):
// sa_handler at 0, a 128-byte sigset_t, sa_flags (4 bytes) at 136, then
// sa_restorer at 144.
//
// A Linux-ABI process does not. Its musl converts to the kernel's
// k_sigaction first -- handler at 0, flags at 8, restorer at 16, mask at 24,
// thirty-two bytes in all -- and this used the native offsets for both, so
// every Alpine program that asked for the old action had 8 bytes written 112
// bytes past the end of the struct, into whatever its stack held there.
#define SA_HANDLER_OFF 0
#define SA_RESTORER_OFF 144
#define SA_FLAGS_OFF(p) ((p)->syscall_map ? 8 : 136)
#define SA_RESTORER_OFF(p) ((p)->syscall_map ? 16 : 144)
// rt_sigaction: store the handler + restorer so deliver_signals() (called
// from syscall()'s tail, kernel/sys/syscall.c) can actually jump to user
@ -108,15 +113,30 @@ sys_rt_sigaction(void)
argaddr(2, &oldactp);
if (sig <= 0 || sig >= 32) return -1;
struct proc *p = myproc();
if (oldactp) {
put_user(myproc()->sig_handler[sig], oldactp + SA_HANDLER_OFF);
put_user(myproc()->sig_restorer[sig], oldactp + SA_RESTORER_OFF);
put_user(p->sig_handler[sig], oldactp + SA_HANDLER_OFF);
put_user(p->sig_restorer[sig], oldactp + SA_RESTORER_OFF(p));
if (p->syscall_map) {
put_user(p->sig_flags[sig], oldactp + SA_FLAGS_OFF(p));
} else {
uint32 fl = (uint32)p->sig_flags[sig];
put_user(fl, oldactp + SA_FLAGS_OFF(p));
}
}
if (actp) {
copy_from_user(&myproc()->sig_handler[sig], actp + SA_HANDLER_OFF,
sizeof(myproc()->sig_handler[sig]));
copy_from_user(&myproc()->sig_restorer[sig], actp + SA_RESTORER_OFF,
sizeof(myproc()->sig_restorer[sig]));
uint64 h, r, fl = 0;
if (copy_from_user(&h, actp + SA_HANDLER_OFF, sizeof(h)) < 0 ||
copy_from_user(&r, actp + SA_RESTORER_OFF(p), sizeof(r)) < 0 ||
copy_from_user(&fl, actp + SA_FLAGS_OFF(p),
p->syscall_map ? 8 : 4) < 0)
return -EFAULT;
// SIGKILL and SIGSTOP cannot be caught or ignored.
if (sig == SIGKILL || sig == SIGSTOP)
return -EINVAL;
p->sig_handler[sig] = h;
p->sig_restorer[sig] = r;
p->sig_flags[sig] = fl;
}
return 0;
}
@ -195,6 +215,16 @@ deliver_signals(struct trapframe *tf)
// Except for a signal that was blocked when it arrived: sigsend()
// left it pending without acting, and now that it is deliverable its
// default action happens here.
// SIGSTOP cannot be caught or ignored; the other three stop only by
// default. Stopped here and resumed here, by SIGCONT or SIGKILL.
if (sig == SIGSTOP ||
(sig_default_stops(sig) && myproc()->sig_handler[sig] == 0)) {
myproc()->pending_signals &= ~(1ULL << sig);
proc_stop(sig);
if (myproc()->killed)
exit(W_EXITCODE(0, myproc()->killsig ? myproc()->killsig : SIGKILL));
continue;
}
if (myproc()->sig_handler[sig] <= 1) {
myproc()->pending_signals &= ~(1ULL << sig);
if (myproc()->sig_handler[sig] == 0 && sig_default_kills(sig)) {