From e4258015b7cb313aff2e0cde9b9038ffa8f2c598 Mon Sep 17 00:00:00 2001
From: Justine Tunney <jtunney@gmail.com>
Date: Thu, 23 Jun 2022 14:09:32 -0700
Subject: [PATCH] Improve detection of getrandom / getentropy

It's been reported that the 500th system call getentropy() isn't present
on Darwin Kernel Version 15.6.0 virtual machines. We work around this by
ignoring SIGSYS temporarily.
---
 libc/rand/getrandom.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/libc/rand/getrandom.c b/libc/rand/getrandom.c
index 5b9f234b6..77caf1b16 100644
--- a/libc/rand/getrandom.c
+++ b/libc/rand/getrandom.c
@@ -19,6 +19,8 @@
 #include "libc/bits/bits.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/strace.internal.h"
+#include "libc/calls/struct/sigaction.h"
+#include "libc/calls/struct/sigset.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/calls/syscall_support-nt.internal.h"
 #include "libc/dce.h"
@@ -37,6 +39,7 @@
 #include "libc/sysv/consts/auxv.h"
 #include "libc/sysv/consts/grnd.h"
 #include "libc/sysv/consts/o.h"
+#include "libc/sysv/consts/sig.h"
 #include "libc/sysv/errfuns.h"
 
 static bool have_getrandom;
@@ -123,10 +126,20 @@ ssize_t getrandom(void *p, size_t n, unsigned f) {
 static textstartup void getrandom_init(void) {
   int e, rc;
   e = errno;
+  struct sigaction sa, oldsa;
+  if (IsBsd()) {
+    sa.sa_flags = 0;
+    sa.sa_handler = SIG_IGN;
+    sigemptyset(&sa.sa_mask);
+    sigaction(SIGSYS, &sa, &oldsa);
+  }
   if (!(rc = sys_getrandom(0, 0, 0))) {
     have_getrandom = true;
   }
-  KERNTRACE("sys_getrandom(0,0,0) → %d% m");
+  STRACE("sys_getrandom(0,0,0) → %d% m", rc);
+  if (IsBsd()) {
+    sigaction(SIGSYS, &oldsa, 0);
+  }
   errno = e;
 }