threads: add threadvars allocator and free func

Mostly meant to help unittests and fuzz targets alloc the storage
correctly.

src/Makefile.am

@@ -1009,6 +1009,7 @@ libsuricata_c_a_SOURCES = \
 	thread-callbacks.c \
 	thread-storage.c \
 	threads.c \
+	threadvars.c \
 	tm-modules.c \
 	tm-queuehandlers.c \
 	tm-queues.c \

src/threadvars.c

@@ -0,0 +1,47 @@
+/* Copyright (C) 2026 Open Information Security Foundation
+ *
+ * You can copy, redistribute or modify this Program under the terms of
+ * the GNU General Public License version 2 as published by the Free
+ * Software Foundation.
+ *
+ * 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
+ * version 2 along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include "suricata-common.h"
+#include "threadvars.h"
+#include "thread-storage.h"
+
+/**
+ * \brief Allocate a new ThreadVars structure.
+ *
+ * \retval NULL if allocation failed.
+ * \retval Pointer to newly allocated ThreadVars structure.
+ */
+ThreadVars *ThreadVarsAlloc(void)
+{
+    ThreadVars *tv = SCCalloc(1, sizeof(ThreadVars) + SCThreadStorageSize());
+    if (tv == NULL)
+        return NULL;
+    SC_ATOMIC_INIT(tv->flags);
+    return tv;
+}
+
+/**
+ * \brief Free a ThreadVars structure.
+ *
+ * \param tv Pointer to ThreadVars structure to be freed.
+ */
+void ThreadVarsFree(ThreadVars *tv)
+{
+    if (tv == NULL)
+        return;
+    SCFree(tv);
+}

src/threadvars.h

@@ -143,4 +143,19 @@ typedef struct ThreadVars_ {
 #define THREAD_SET_PRIORITY     0x02 /** Real time priority */
 #define THREAD_SET_AFFTYPE      0x04 /** Priority and affinity */
 
+/**
+ * \brief Allocate a new ThreadVars structure.
+ *
+ * \retval NULL if allocation failed.
+ * \retval Pointer to newly allocated ThreadVars structure.
+ */
+ThreadVars *ThreadVarsAlloc(void);
+
+/**
+ * \brief Free a ThreadVars structure.
+ *
+ * \param tv Pointer to ThreadVars structure to be freed.
+ */
+void ThreadVarsFree(ThreadVars *tv);
+
 #endif /* SURICATA_THREADVARS_H */