Make the salsa20 random stream thread local

configure.ac

@@ -336,6 +336,8 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[
 
 AX_CHECK_CATCHABLE_SEGV
 AX_CHECK_CATCHABLE_ABRT
+AX_TLS([AC_MSG_RESULT(thread local storage is supported)],
+       [AC_MSG_RESULT(thread local storage is not supported)])
 
 LT_INIT
 AC_SUBST(LIBTOOL_DEPS)

m4/ax_tls.m4

@@ -0,0 +1,74 @@
+# ===========================================================================
+#          https://www.gnu.org/software/autoconf-archive/ax_tls.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_TLS([action-if-found], [action-if-not-found])
+#
+# DESCRIPTION
+#
+#   Provides a test for the compiler support of thread local storage (TLS)
+#   extensions. Defines TLS if it is found. Currently knows about C++11,
+#   GCC/ICC, and MSVC. I think SunPro uses the same as GCC, and Borland
+#   apparently supports either.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Alan Woodland <ajw05@aber.ac.uk>
+#   Copyright (c) 2010 Diego Elio Petteno` <flameeyes@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 14
+
+AC_DEFUN([AX_TLS], [
+  AC_MSG_CHECKING([for thread local storage (TLS) class])
+  AC_CACHE_VAL([ac_cv_tls],
+   [for ax_tls_keyword in thread_local _Thread_local __thread '__declspec(thread)' none; do
+       AS_CASE([$ax_tls_keyword],
+          [none], [ac_cv_tls=none ; break],
+          [AC_TRY_COMPILE(
+              [#include <stdlib.h>
+               static void
+               foo(void) {
+               static ] $ax_tls_keyword [ int bar;
+               exit(1);
+               }],
+               [],
+               [ac_cv_tls=$ax_tls_keyword ; break],
+               ac_cv_tls=none
+           )])
+    done
+  ])
+  AC_MSG_RESULT([$ac_cv_tls])
+
+  AS_IF([test "$ac_cv_tls" != "none"],
+    [AC_DEFINE_UNQUOTED([TLS],[$ac_cv_tls],[If the compiler supports a TLS storage class define it to that here])
+     m4_ifnblank([$1],[$1])],
+    [m4_ifnblank([$2],[$2])])
+])

src/libsodium/randombytes/salsa20/randombytes_salsa20_random.c

@@ -63,6 +63,10 @@ BOOLEAN NTAPI RtlGenRandom(PVOID RandomBuffer, ULONG RandomBufferLength);
 # define SSIZE_MAX (SIZE_MAX / 2 - 1)
 #endif
 
+#ifndef TLS
+# define TLS
+#endif
+
 typedef struct Salsa20RandomGlobal_ {
     int           initialized;
     int           random_data_source_fd;
@@ -86,7 +90,7 @@ static Salsa20RandomGlobal global = {
     SODIUM_C99(.random_data_source_fd =) -1
 };
 
-static Salsa20Random stream = {
+static TLS Salsa20Random stream = {
     SODIUM_C99(.initialized =) 0,
     SODIUM_C99(.rnd32_outleft =) (size_t) 0U
 };