--- Libc/Libc-825.26/stdlib/FreeBSD/abort.c
+++ Libc/Libc-1669.40.2/stdlib/FreeBSD/abort.c
@@ -27,6 +27,9 @@
  * SUCH DAMAGE.
  */
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wstrict-prototypes"
+
 #if defined(LIBC_SCCS) && !defined(lint)
 static char sccsid[] = "@(#)abort.c	8.1 (Berkeley) 6/4/93";
 #endif /* LIBC_SCCS and not lint */
@@ -40,15 +43,21 @@
 #include <stddef.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <pthread_workqueue.h>
 #include "un-namespace.h"
 
 #include "libc_private.h"
+#include "stdio/FreeBSD/local.h" // for __cleanup
 
-#include "CrashReporterClient.h"
+#if __has_include(<CrashReporterClient.h>)
+#include <CrashReporterClient.h>
+#else
+#define CRGetCrashLogMessage() NULL
+#define CRSetCrashLogMessage(...)
+#endif
 #include "_simple.h"
 
-extern void (*__cleanup)();
-extern void __abort(void) __dead2;
+extern void __abort(void) __cold __dead2;
 
 #define TIMEOUT	10000	/* 10 milliseconds */
 
@@ -61,11 +70,23 @@
 		CRSetCrashLogMessage("abort() called");
 
 	/*
+	 * Fetch pthread_self() now, before we start masking signals.
+	 * pthread_self will abort or crash if the pthread's signature
+	 * appears corrupt. aborting inside abort is painful, so let's get
+	 * that out of the way before we go any further.
+	 */
+	pthread_t self = pthread_self();
+
+	/*
 	 * POSIX requires we flush stdio buffers on abort.
 	 * XXX ISO C requires that abort() be async-signal-safe.
 	 */
 	if (__cleanup)
-		(*__cleanup)();
+#ifdef __APPLE__
+		_cleanup();
+#else
+	    (*__cleanup)();
+#endif // __APPLE__
 
 	sigfillset(&act.sa_mask);
 	/*
@@ -74,24 +95,32 @@
 	 */
 	sigdelset(&act.sa_mask, SIGABRT);
 
+	/*
+	 * Don't block SIGSEGV since we might trigger a segfault if the pthread
+	 * struct is corrupt. The end user behavior is that the program will
+	 * terminate with a SIGSEGV instead of a SIGABRT which is acceptable. If
+	 * the user registers a SIGSEGV handler, then they are responsible for
+	 * dealing with any corruption themselves and abort may not work.
+	 * rdar://48853131
+	 */
+	sigdelset(&act.sa_mask, SIGSEGV);
+	sigdelset(&act.sa_mask, SIGBUS);
+
 	/* <rdar://problem/7397932> abort() should call pthread_kill to deliver a signal to the aborting thread 
 	 * This helps gdb focus on the thread calling abort()
 	 */
-	if (__is_threaded) {
-	    /* Block all signals on all other threads */
-	    sigset_t fullmask;
-	    sigfillset(&fullmask);
-	    (void)_sigprocmask(SIG_SETMASK, &fullmask, NULL);
 
-	    /* <rdar://problem/8400096> Set the workqueue killable */
-	    __pthread_workqueue_setkill(1);
+	/* Block all signals on all other threads */
+	sigset_t fullmask;
+	sigfillset(&fullmask);
+	(void)_sigprocmask(SIG_SETMASK, &fullmask, NULL);
 
-	    (void)pthread_sigmask(SIG_SETMASK, &act.sa_mask, NULL);
-	    (void)pthread_kill(pthread_self(), SIGABRT);
-	} else {
-	    (void)_sigprocmask(SIG_SETMASK, &act.sa_mask, NULL);
-	    (void)kill(getpid(), SIGABRT);
-	}
+	/* <rdar://problem/8400096> Set the workqueue killable */
+	__pthread_workqueue_setkill(1);
+
+	(void)pthread_sigmask(SIG_SETMASK, &act.sa_mask, NULL);
+	(void)pthread_kill(self, SIGABRT);
+
 	usleep(TIMEOUT); /* give time for signal to happen */
 
 	/*
@@ -108,6 +137,10 @@
 
 	if (!CRGetCrashLogMessage())
 		CRSetCrashLogMessage("__abort() called");
+
+	/* Fetch pthread_self() before masking signals - see above. */
+	pthread_t self = pthread_self();
+
 	act.sa_handler = SIG_DFL;
 	act.sa_flags = 0;
 	sigfillset(&act.sa_mask);
@@ -117,21 +150,18 @@
 	/* <rdar://problem/7397932> abort() should call pthread_kill to deliver a signal to the aborting thread 
 	 * This helps gdb focus on the thread calling abort()
 	 */
-	if (__is_threaded) {
-	    /* Block all signals on all other threads */
-	    sigset_t fullmask;
-	    sigfillset(&fullmask);
-	    (void)_sigprocmask(SIG_SETMASK, &fullmask, NULL);
 
-	    /* <rdar://problem/8400096> Set the workqueue killable */
-	    __pthread_workqueue_setkill(1);
+	/* Block all signals on all other threads */
+	sigset_t fullmask;
+	sigfillset(&fullmask);
+	(void)_sigprocmask(SIG_SETMASK, &fullmask, NULL);
 
-	    (void)pthread_sigmask(SIG_SETMASK, &act.sa_mask, NULL);
-	    (void)pthread_kill(pthread_self(), SIGABRT);
-	} else {
-	    (void)_sigprocmask(SIG_SETMASK, &act.sa_mask, NULL);
-	    (void)kill(getpid(), SIGABRT);
-	}
+	/* <rdar://problem/8400096> Set the workqueue killable */
+	__pthread_workqueue_setkill(1);
+
+	(void)pthread_sigmask(SIG_SETMASK, &act.sa_mask, NULL);
+	(void)pthread_kill(self, SIGABRT);
+
 	usleep(TIMEOUT); /* give time for signal to happen */
 
 	/* If for some reason SIGABRT was not delivered, we exit using __builtin_trap
@@ -145,7 +175,7 @@
 	__builtin_trap();
 }
 
-__private_extern__ void
+void
 abort_report_np(const char *fmt, ...)
 {
 	_SIMPLE_STRING s;
@@ -160,3 +190,4 @@
 		CRSetCrashLogMessage(fmt); /* the format string is better than nothing */
 	abort();
 }
+#pragma clang diagnostic pop