qsort_r: new module, for GNU-style qsort_r

This works even on FreeBSD, which has an incompatible qsort_r API.
* MODULES.html.sh: Add it.
* doc/glibc-functions/qsort_r.texi: It's now supported.
* lib/qsort.c: New file, taken from glibc with minor changes
inside "#ifndef _LIBC" and with an unnecessary "#include <alloca.h>"
removed.
* lib/qsort_r.c: New file, compiled only on FreeBSD.
* lib/stdlib.in.h (qsort_r): Declare in the usual way.
* m4/stdlib_h.m4 (gl_STDLIB_H_DEFAULTS):
* modules/qsort_r, modules/qsort_r-tests: New files.
* modules/stdlib (Makefile): Set up its defaults.
* tests/test-qsort_r.c: New file.

1 files changed, 51 insertions, 0 deletions

diff --git a/lib/qsort_r.c b/lib/qsort_r.c
new file mode 100644
index 0000000000..ad68efa50c
--- /dev/null
+++ b/lib/qsort_r.c
@@ -0,0 +1,51 @@
+/* Reentrant sort function.
+
+   Copyright 2014 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   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 along
+   with this program; if not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert.  */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+/* This file is compiled only when the system has a qsort_r that needs
+   to be replaced because it has the BSD signature rather than the GNU
+   signature.  */
+
+struct thunk
+{
+  int (*cmp) (void const *, void const *, void *);
+  void *arg;
+};
+
+static int
+thunk_cmp (void *thunk, void const *a, void const *b)
+{
+  struct thunk *th = thunk;
+  return th->cmp (a, b, th->arg);
+}
+
+void
+qsort_r (void *base, size_t nmemb, size_t size,
+         int (*cmp) (void const *, void const *, void *),
+         void *arg)
+{
+# undef qsort_r
+  struct thunk thunk;
+  thunk.cmp = cmp;
+  thunk.arg = arg;
+  qsort_r (base, nmemb, size, &thunk, thunk_cmp);
+}