1 files changed, 36 insertions, 2 deletions

diff --git a/include/stdlib.h b/include/stdlib.h
index bf1a612190ee..754e8f5f5fd4 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -311,8 +311,8 @@ int	 mergesort_b(void *, size_t, size_t, int (^)(const void *, const void *));
 int	 mkostemp(char *, int);
 int	 mkostemps(char *, int, int);
 int	 mkostempsat(int, char *, int, int);
-void	 qsort_r(void *, size_t, size_t, void *,
-	    int (*)(void *, const void *, const void *));
+void	 qsort_r(void *, size_t, size_t,
+	    int (*)(const void *, const void *, void *), void *);
 int	 radixsort(const unsigned char **, int, const unsigned char *,
 	    unsigned);
 void	*reallocarray(void *, size_t, size_t) __result_use_check
@@ -332,6 +332,40 @@ __int64_t
 __uint64_t
 	 strtouq(const char *, char **, int);
 
+/*
+ * In FreeBSD 14, the prototype of qsort_r() was modified to comply with
+ * POSIX.  The standardized qsort_r()'s order of last two parameters was
+ * changed, and the comparator function is now taking thunk as its last
+ * parameter, and both are different from the ones expected by the historical
+ * FreeBSD qsort_r() interface.
+ *
+ * Apply a workaround where we explicitly link against the historical
+ * interface, qsort_r@FBSD_1.0, in case when qsort_r() is called with
+ * the last parameter with a function pointer that exactly matches the
+ * historical FreeBSD qsort_r() comparator signature, so applications
+ * written for the historical interface can continue to work without
+ * modification.
+ */
+#if defined(__generic) || defined(__cplusplus)
+void __qsort_r_compat(void *, size_t, size_t, void *,
+	    int (*)(void *, const void *, const void *));
+__sym_compat(qsort_r, __qsort_r_compat, FBSD_1.0);
+#endif
+#if defined(__generic) && !defined(__cplusplus)
+#define	qsort_r(base, nel, width, arg4, arg5)				\
+    __generic(arg5, int (*)(void *, const void *, const void *),	\
+        __qsort_r_compat, qsort_r)(base, nel, width, arg4, arg5)
+#elif defined(__cplusplus)
+__END_DECLS
+extern "C++" {
+static inline void qsort_r(void *base, size_t nmemb, size_t size,
+    void *thunk, int (*compar)(void *, const void *, const void *)) {
+	__qsort_r_compat(base, nmemb, size, thunk, compar);
+}
+}
+__BEGIN_DECLS
+#endif
+
 extern char *suboptarg;			/* getsubopt(3) external variable */
 #endif /* __BSD_VISIBLE */