Improve quality of raise(), abort(), and tkill()

This change fixes a nasty bug where SIG_IGN and SIG_DFL weren't working
as advertised on BSDs. This change also fixes the tkill() definition on
MacOS so it maps to __pthread_kill().

libc/calls/raise.c

@@ -17,32 +17,45 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
-#include "libc/calls/getconsolectrlevent.internal.h"
 #include "libc/calls/sig.internal.h"
 #include "libc/calls/strace.internal.h"
-#include "libc/calls/struct/sigset.h"
 #include "libc/calls/syscall-sysv.internal.h"
-#include "libc/calls/syscall_support-nt.internal.h"
-#include "libc/nt/console.h"
-#include "libc/nt/errors.h"
-#include "libc/nt/process.h"
-#include "libc/nt/runtime.h"
-#include "libc/nt/synchronization.h"
+#include "libc/dce.h"
+#include "libc/nexgen32e/threaded.h"
 #include "libc/runtime/internal.h"
-#include "libc/runtime/runtime.h"
-#include "libc/str/str.h"
 #include "libc/sysv/consts/sicode.h"
 #include "libc/sysv/consts/sig.h"
+#include "libc/thread/xnu.internal.h"
 
 static textwindows inline bool HasWorkingConsole(void) {
   return !!(__ntconsolemode[0] | __ntconsolemode[1] | __ntconsolemode[2]);
 }
 
+static noubsan void RaiseSigFpe(void) {
+  volatile int x = 0;
+  x = 1 / x;
+}
+
 /**
- * Sends signal to this thread.
+ * Sends signal to self.
+ *
+ * This is basically the same as:
+ *
+ *     tkill(gettid(), sig);
+ *
+ * Note `SIG_DFL` still results in process death for most signals.
+ *
+ * This function is not entirely equivalent to kill() or tkill(). For
+ * example, we raise `SIGTRAP` and `SIGFPE` the natural way, since that
+ * helps us support Windows. So if the raised signal has a signal
+ * handler, then the reported `si_code` might not be `SI_TKILL`.
+ *
+ * On Windows, if a signal results in the termination of the process
+ * then we use the convention `_Exit(128 + sig)` to notify the parent of
+ * the signal number.
  *
  * @param sig can be SIGALRM, SIGINT, SIGTERM, SIGKILL, etc.
- * @return 0 on success or -1 w/ errno
+ * @return 0 if signal was delivered and returned, or -1 w/ errno
  * @asyncsignalsafe
  */
 int raise(int sig) {
@@ -52,28 +65,12 @@ int raise(int sig) {
     DebugBreak();
     rc = 0;
   } else if (sig == SIGFPE) {
-    volatile int x = 0;
-    x = 1 / x;
+    RaiseSigFpe();
     rc = 0;
   } else if (!IsWindows()) {
     rc = sys_tkill(gettid(), sig, 0);
   } else {
-    if (HasWorkingConsole() && (event = GetConsoleCtrlEvent(sig)) != -1) {
-      // XXX: MSDN says "If this parameter is zero, the signal is
-      //      generated in all processes that share the console of the
-      //      calling process." which seems to imply multiple process
-      //      groups potentially. We just shouldn't use this because it
-      //      doesn't make any sense and it's so evil.
-      if (GenerateConsoleCtrlEvent(event, 0)) {
-        SleepEx(100, true);
-        __sig_check(false);
-        rc = 0;
-      } else {
-        rc = __winerr();
-      }
-    } else {
-      rc = __sig_raise(sig, SI_USER);
-    }
+    rc = __sig_raise(sig, SI_TKILL);
   }
   STRACE("...raise(%G) → %d% m", sig, rc);
   return rc;

libc/calls/sigaction.c

@@ -182,8 +182,11 @@ static int __sigaction(int sig, const struct sigaction *act,
       ap = ©
       if (IsXnu()) {
         ap->sa_restorer = (void *)&__sigenter_xnu;
-        ap->sa_handler = (void *)&__sigenter_xnu;
-
+        if (rva < kSigactionMinRva) {
+          ap->sa_sigaction = (void *)(intptr_t)rva;
+        } else {
+          ap->sa_sigaction = (void *)&__sigenter_xnu;
+        }
         // mitigate Rosetta signal handling strangeness
         // https://github.com/jart/cosmopolitan/issues/455
         ap->sa_flags |= SA_SIGINFO;
@@ -193,11 +196,23 @@ static int __sigaction(int sig, const struct sigaction *act,
           ap->sa_restorer = &__restore_rt;
         }
       } else if (IsNetbsd()) {
-        ap->sa_sigaction = (sigaction_f)__sigenter_netbsd;
+        if (rva < kSigactionMinRva) {
+          ap->sa_sigaction = (void *)(intptr_t)rva;
+        } else {
+          ap->sa_sigaction = (sigaction_f)__sigenter_netbsd;
+        }
       } else if (IsFreebsd()) {
-        ap->sa_sigaction = (sigaction_f)__sigenter_freebsd;
+        if (rva < kSigactionMinRva) {
+          ap->sa_sigaction = (void *)(intptr_t)rva;
+        } else {
+          ap->sa_sigaction = (sigaction_f)__sigenter_freebsd;
+        }
       } else if (IsOpenbsd()) {
-        ap->sa_sigaction = (sigaction_f)__sigenter_openbsd;
+        if (rva < kSigactionMinRva) {
+          ap->sa_sigaction = (void *)(intptr_t)rva;
+        } else {
+          ap->sa_sigaction = (sigaction_f)__sigenter_openbsd;
+        }
       } else {
         return enosys();
       }

libc/runtime/abort.c

@@ -17,30 +17,29 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
-#include "libc/calls/sig.internal.h"
+#include "libc/calls/struct/sigaction.h"
 #include "libc/calls/struct/sigset.h"
-#include "libc/dce.h"
-#include "libc/runtime/internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sysv/consts/sig.h"
 
 /**
  * Terminates program abnormally.
  *
- * This function first tries to trigger your SIGABRT handler. If
- * there isn't one or execution resumes, then abort() terminates
- * the program using an escalating variety methods of increasing
- * brutality.
+ * This function first tries to trigger your SIGABRT handler. If the
+ * signal handler returns, then `signal(SIGABRT, SIG_DFL)` is called
+ * before SIGABRT is raised again.
  *
  * @asyncsignalsafe
  * @noreturn
  */
-privileged void abort(void) {
-  sigset_t sm;
-  sigfillset(&sm);
-  sigdelset(&sm, SIGABRT);
-  sigprocmask(SIG_SETMASK, &sm, 0);
+wontreturn void abort(void) {
+  sigset_t m;
+  sigemptyset(&m);
+  sigaddset(&m, SIGABRT);
+  sigprocmask(SIG_UNBLOCK, &m, 0);
   raise(SIGABRT);
-  __restorewintty();
-  _Exit(128 + SIGABRT);
+  signal(SIGABRT, SIG_DFL);
+  raise(SIGABRT);
+  asm("hlt");
+  unreachable;
 }

libc/runtime/runtime.h

@@ -65,7 +65,7 @@ void _exit(int) libcesque wontreturn;
 void _Exit(int) libcesque wontreturn;
 void _Exit1(int) libcesque wontreturn;
 void quick_exit(int) wontreturn;
-void abort(void) wontreturn noinstrument;
+void abort(void) wontreturn;
 int __cxa_atexit(void *, void *, void *) libcesque;
 int atfork(void *, void *) libcesque;
 int atexit(void (*)(void)) libcesque;

libc/sysv/calls/sys_tkill.s

@@ -1,2 +1,2 @@
 .include "o/libc/sysv/macros.internal.inc"
-.scall sys_tkill,0x13e0771b121690c8,globl,hidden
+.scall sys_tkill,0x13e0771b121480c8,globl,hidden

libc/sysv/consts.sh

@@ -533,7 +533,7 @@ syscon	sicode	SI_TKILL				-6			0x80000000		0x010007		-1			-5			-6			# sent by tk
 syscon	sicode	SI_MESGQ				-3			0x010005		0x010005		0x80000000		-4			-3			# sent by mq_notify(2); lool
 syscon	sicode	SI_ASYNCIO				-4			0x010004		0x010004		0x80000000		-3			-4			# aio completion; no thank you
 syscon	sicode	SI_ASYNCNL				-60			0x80000000		0x80000000		0x80000000		0x80000000		0x80000000		# aio completion for dns; the horror
-syscon	sicode	SI_KERNEL				0x80			0x80000000		0x010006		0x80000000		0x80000000		0x80			# wut; openbsd defines as si_code>0
+syscon	sicode	SI_KERNEL				128			0x80000000		0x010006		0x80000000		0x80000000		0x80			# wut; openbsd defines as si_code>0
 syscon	sicode	SI_NOINFO				32767			0x80000000		0			32767			32767			32767			# no signal specific info available
 syscon	sicode	CLD_EXITED				1			1			1			1			1			1			# SIGCHLD; child exited; unix consensus
 syscon	sicode	CLD_KILLED				2			2			2			2			2			2			# SIGCHLD; child terminated w/o core; unix consensus

libc/sysv/syscalls.sh

@@ -98,7 +98,7 @@ scall	__sys_wait4		0x1c100b007200703d	globl hidden
 scall	sys_kill		0x02507a025202503e	globl hidden # kill(pid, sig, 1) b/c xnu
 scall	sys_killpg		0x092fff092fffffff	globl hidden
 scall	sys_clone		0x11fffffffffff038	globl hidden
-scall	sys_tkill		0x13e0771b121690c8	globl hidden # thr_kill() on freebsd; _lwp_kill() on netbsd; thrkill() on openbsd where arg3 should be 0; bsdthread_terminate() on XNU which only has 1 arg
+scall	sys_tkill		0x13e0771b121480c8	globl hidden # thr_kill() on freebsd; _lwp_kill() on netbsd; thrkill() on openbsd where arg3 should be 0; __pthread_kill() on XNU
 scall	sys_futex		0x0a6053fffffff0ca	globl hidden # raises SIGSYS on NetBSD
 scall	set_robust_list		0x0a7ffffffffff111	globl
 scall	get_robust_list		0x0a8ffffffffff112	globl

libc/thread/xnu.internal.h

@@ -12,6 +12,7 @@ int bsdthread_create(void *func, void *func_arg, void *stack, void *pthread,
                      uint32_t flags);
 int bsdthread_terminate(void *stackaddr, size_t freesize, uint32_t port,
                         uint32_t sem);
+int __pthread_kill(uint32_t port, int sig);
 int bsdthread_register(
     void (*threadstart)(void *pthread, int machport, void *(*func)(void *),
                         void *arg, intptr_t *, unsigned),