basic + fundamental: Clean up includes

Split out of #37344.

src/basic/sort-util.c

@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <stdlib.h>
+
 #include "alloc-util.h"
 #include "sort-util.h"
 
@@ -28,6 +30,40 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
         return NULL;
 }
 
+void* bsearch_safe(const void *key, const void *base, size_t nmemb, size_t size, comparison_fn_t compar) {
+        /**
+        * Normal bsearch requires base to be nonnull. Here were require
+        * that only if nmemb > 0.
+        */
+
+        if (nmemb <= 0)
+                return NULL;
+
+        assert(base);
+        return bsearch(key, base, nmemb, size, compar);
+}
+
+void qsort_safe(void *base, size_t nmemb, size_t size, comparison_fn_t compar) {
+        /**
+         * Normal qsort requires base to be nonnull. Here were require
+         * that only if nmemb > 0.
+         */
+
+        if (nmemb <= 1)
+                return;
+
+        assert(base);
+        qsort(base, nmemb, size, compar);
+}
+
+void qsort_r_safe(void *base, size_t nmemb, size_t size, comparison_userdata_fn_t compar, void *userdata) {
+        if (nmemb <= 1)
+                return;
+
+        assert(base);
+        qsort_r(base, nmemb, size, compar, userdata);
+}
+
 int cmp_int(const int *a, const int *b) {
         return CMP(*a, *b);
 }