From 4a5947e10ec17586ddc06ce54c3e4c98a4ca300a Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Mon, 10 Jul 2023 21:17:25 +0200
Subject: [PATCH] libc: Implement signal()

---
 libc/include/signal.h |  5 +++++
 libc/src/signal.cpp   | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/libc/include/signal.h b/libc/include/signal.h
index 3cfa36cf..814ede80 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -8,6 +8,8 @@
 
 typedef int sig_atomic_t;
 
+#define SIG_ERR (__simple_sighandler_t)(-3)
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -19,6 +21,9 @@ extern "C"
     int sigaction(int signo, const struct sigaction* act, struct sigaction* oldact);
 #pragma GCC pop_options
 
+    /* Change the current thread's signal disposition for a specific signal. */
+    __simple_sighandler_t signal(int signo, __simple_sighandler_t handler);
+
     /* Send a signal to a specific process. */
     int kill(pid_t pid, int signo);
 
diff --git a/libc/src/signal.cpp b/libc/src/signal.cpp
index 9b55e78b..64849364 100644
--- a/libc/src/signal.cpp
+++ b/libc/src/signal.cpp
@@ -13,6 +13,18 @@ extern "C"
         __errno_return(rc, int);
     }
 
+    __simple_sighandler_t signal(int signo, __simple_sighandler_t handler)
+    {
+        struct sigaction act, oldact;
+        act.sa_handler = handler;
+        sigemptyset(&act.sa_mask);
+        act.sa_flags = 0;
+
+        if (sigaction(signo, &act, &oldact) < 0) return SIG_ERR;
+
+        return oldact.sa_handler;
+    }
+
     int kill(pid_t pid, int signo)
     {
         long rc = syscall(SYS_kill, pid, signo);