From 60d68b74e1677510de0fb565750492960dedbe3a Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Mon, 10 Jul 2023 20:30:37 +0200
Subject: [PATCH] kernel: Define a good set of default signals

Most of these have POSIX-defined numbers.
---
 kernel/src/thread/Thread.cpp | 25 ++++++++++++++++++++-----
 libc/include/bits/signal.h   | 18 +++++++++++++++++-
 2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/kernel/src/thread/Thread.cpp b/kernel/src/thread/Thread.cpp
index 6031fc55..d9b239a5 100644
--- a/kernel/src/thread/Thread.cpp
+++ b/kernel/src/thread/Thread.cpp
@@ -4,6 +4,7 @@
 #include "thread/Scheduler.h"
 #include <bits/atfile.h>
 #include <bits/open-flags.h>
+#include <bits/signal.h>
 #include <bits/waitpid.h>
 #include <luna/Alloc.h>
 #include <luna/Atomic.h>
@@ -106,26 +107,40 @@ enum class DefaultSignalAction
 };
 
 static constexpr DefaultSignalAction default_actions[] = {
-    DefaultSignalAction::Terminate // SIGABRT
+    DefaultSignalAction::Terminate, // SIGHUP
+    DefaultSignalAction::Terminate, // SIGINT
+    DefaultSignalAction::Terminate, // SIGQUIT (dump core)
+    DefaultSignalAction::Terminate, // SIGILL  (dump core)
+    DefaultSignalAction::Terminate, // SIGTRAP (dump core)
+    DefaultSignalAction::Terminate, // SIGABRT (dump core)
+    DefaultSignalAction::Ignore,    // SIGCHLD
+    DefaultSignalAction::Terminate, // SIGFPE  (dump core)
+    DefaultSignalAction::Terminate, // SIGKILL
+    DefaultSignalAction::Terminate, // SIGSTOP (FIXME: Support stopping and continuing)
+    DefaultSignalAction::Terminate, // SIGSEGV (dump core)
+    DefaultSignalAction::Ignore,    // SIGCONT (FIXME: Support stopping and continuing)
+    DefaultSignalAction::Terminate, // SIGPIPE
+    DefaultSignalAction::Terminate, // SIGALRM
+    DefaultSignalAction::Terminate, // SIGTERM
 };
 
 void Thread::process_pending_signals(Registers* current_regs)
 {
     for (int i = 0; i < NSIG; i++)
     {
-        if (signal_mask & (1 << i)) continue;
+        int signo = i + 1;
+        if (signo != SIGKILL && signo != SIGSTOP && signal_mask & (1 << i)) continue;
         if (pending_signals & (1 << i))
         {
-            int signo = i + 1;
             pending_signals &= ~(1 << i);
             kinfoln("signal: executing signal %d for thread %ld", signo, id);
             auto handler = signal_handlers[i];
-            if (handler.sa_handler == SIG_IGN)
+            if (signo != SIGKILL && signo != SIGSTOP && handler.sa_handler == SIG_IGN)
             {
                 kinfoln("signal: ignoring signal (handler=SIG_IGN)");
                 return;
             }
-            if (handler.sa_handler == SIG_DFL)
+            if (handler.sa_handler == SIG_DFL || signo == SIGKILL || signo == SIGSTOP)
             {
             default_signal:
                 if (id == 1)
diff --git a/libc/include/bits/signal.h b/libc/include/bits/signal.h
index c562c5a8..9cc47724 100644
--- a/libc/include/bits/signal.h
+++ b/libc/include/bits/signal.h
@@ -18,9 +18,25 @@ struct sigaction
     void* __sa_sigreturn = nullptr;
 };
 
+// The signals with explicit numbers have portable signal numbers.
 enum __signals
 {
-    SIGABRT = 1,
+    SIGHUP = 1,
+    SIGINT = 2,
+    SIGQUIT = 3,
+    SIGILL = 4,
+    SIGTRAP = 5,
+    SIGABRT = 6,
+    SIGCHLD,
+    SIGFPE = 8,
+    SIGKILL = 9,
+    SIGSTOP,
+    SIGSEGV = 11,
+    SIGCONT,
+    SIGPIPE = 13,
+    SIGALRM = 14,
+    SIGTERM = 15,
+    // FIXME: Add the remaining signals.
     __NSIG,
 };