libc: Rewrite abort() using the new signals

libc/src/stdlib.cpp

@@ -6,6 +6,7 @@
 #include <luna/NumberParsing.h>
 #include <luna/Sort.h>
 #include <luna/Utf8.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -99,7 +100,25 @@ extern "C"
 
     __noreturn void abort()
     {
-        syscall(SYS_exit, 255);
+        // First, try to unblock SIGABRT and then raise it.
+        sigset_t set;
+        sigemptyset(&set);
+        sigaddset(&set, SIGABRT);
+        sigprocmask(SIG_UNBLOCK, &set, nullptr);
+
+        raise(SIGABRT);
+
+        // Still here? The program must have catched it. Reset the disposition to default.
+        struct sigaction act;
+        act.sa_handler = SIG_DFL;
+        sigemptyset(&act.sa_mask);
+        act.sa_flags = 0;
+        sigaction(SIGABRT, &act, nullptr);
+
+        raise(SIGABRT);
+
+        // There is no way we could end up here, unless there is some sort of race condition or the kernel decided to
+        // change the default action for SIGABRT because it's a Tuesday.
         __builtin_unreachable();
     }