From 462b4baf33fce4b7876c4269f545941d7ec7858a Mon Sep 17 00:00:00 2001
From: Vicent Marti <tanoku@gmail.com>
Date: Thu, 23 Feb 2017 16:36:20 +0100
Subject: [PATCH] ruby_setenv: Do not allow on multi-threaded programs

---
 hash.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hash.c b/hash.c
index 1867c0999c198c..a4f519202f537a 100644
--- a/hash.c
+++ b/hash.c
@@ -3382,9 +3382,18 @@ check_envname(const char *name)
 }
 #endif
 
+static void
+check_running_threads(void)
+{
+    if (!rb_thread_alone())
+        rb_raise(rb_eRuntimeError, "cannot setenv() in a multi-threaded program");
+}
+
 void
 ruby_setenv(const char *name, const char *value)
 {
+    check_running_threads();
+
 #if defined(_WIN32)
 # if defined(MINGW_HAS_SECURE_API) || RUBY_MSVCRT_VERSION >= 80
 #   define HAVE__WPUTENV_S 1