Prep v240: Add check for qsort_r() and the function if not provided.

As elogind supports musl-libc, we have to remedy the situation that
upstream decided to make use of qsort_r(). This function is not
provided by musl-libc, so we have to provide an own variant.

The variant is an adaption of the qsort_r() algorithm found in
glibc-2.28, the disclaimer from their source files have been added.

Bug: #83
Signed-off-by: Sven Eden <sven.eden@prydeworx.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/src/shared/qsort_r_missing.h b/src/shared/qsort_r_missing.h
new file mode 100644
index 000000000..32c036c0d
--- /dev/null
+++ b/src/shared/qsort_r_missing.h
@@ -0,0 +1,34 @@
+#pragma once
+#ifndef ELOGIND_SRC_SHARED_QSORT_R_MISSING_H_INCLUDED
+#define ELOGIND_SRC_SHARED_QSORT_R_MISSING_H_INCLUDED
+
+/***
+  This file is part of elogind.
+
+  Copyright 2017-2018 Sven Eden
+
+  elogind is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  elogind 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with elogind; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <stdlib.h>
+
+#if HAVE_QSORT_R == 0
+
+typedef int (*compare_fn_t) (const void *, const void *, void *);
+
+void qsort_r (void *base_, size_t nmemb_, size_t size_, compare_fn_t comp_, void *arg_);
+
+#endif // qsort_r() missing
+
+#endif // ELOGIND_SRC_SHARED_QSORT_R_MISSING_H_INCLUDED