lib: Create tst_tmpdir.h

This fixes our sparse warning:

tst_tmpdir.c:347:6: warning: Symbol 'tst_purge_dir' has no prototype or
library ('tst_') prefix. Should it be static?

Header needs to be added also to include/tst_test.h (for tests which use
tst_purge_dir, e.g. creat08.c).

Link: https://lore.kernel.org/ltp/20240712081359.116227-2-pvorel@suse.cz/
Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
Reviewed-by: Li Wang <liwang@redhat.com>
Reviewed-by: Avinesh Kumar <akumar@suse.de>
Signed-off-by: Petr Vorel <pvorel@suse.cz>

include/tst_device.h

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (c) 2016-2019 Cyril Hrubis <chrubis@suse.cz>
+ * Copyright (c) Linux Test Project, 2019-2024
  */
 
 #ifndef TST_DEVICE_H__
@@ -101,11 +102,6 @@ int tst_dev_sync(int fd);
  */
 unsigned long tst_dev_bytes_written(const char *dev);
 
-/*
- * Wipe the contents of given directory but keep the directory itself
- */
-void tst_purge_dir(const char *path);
-
 /*
  * Find the file or path belongs to which block dev
  * @path       Path to find the backing dev

include/tst_test.h

@@ -46,6 +46,7 @@
 #include "tst_memutils.h"
 #include "tst_arch.h"
 #include "tst_fd.h"
+#include "tst_tmpdir.h"
 
 void tst_res_(const char *file, const int lineno, int ttype,
               const char *fmt, ...)

include/tst_tmpdir.h

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2017 Cyril Hrubis <chrubis@suse.cz>
+ * Copyright (c) 2020 Martin Doucha <mdoucha@suse.cz>
+ */
+
+#ifndef TST_TMPDIR_H__
+#define TST_TMPDIR_H__
+
+/**
+ * tst_purge_dir - Wipe the content of given directory.
+ *
+ * Wipe the content of given directory but keep the directory itself.
+ *
+ * @path: Path of the directory to be wiped.
+ */
+void tst_purge_dir(const char *path);
+
+#endif /* TST_TMPDIR_H__ */

lib/tst_tmpdir.c

@@ -72,6 +72,7 @@
 
 #include "test.h"
 #include "safe_macros.h"
+#include "tst_tmpdir.h"
 #include "ltp_priv.h"
 #include "lapi/futex.h"