posix_memalign: New module.

* lib/stdlib.in.h (posix_memalign): New declaration.
* lib/posix_memalign.c: New file.
* m4/posix_memalign.m4: New file.
* m4/stdlib_h.m4 (gl_STDLIB_H): Test whether posix_memalign is declared.
(gl_STDLIB_H_DEFAULTS): Initialize GNULIB_POSIX_MEMALIGN,
HAVE_POSIX_MEMALIGN, REPLACE_POSIX_MEMALIGN.
* modules/stdlib (Makefile.am): Substitute GNULIB_POSIX_MEMALIGN,
HAVE_POSIX_MEMALIGN, REPLACE_POSIX_MEMALIGN.
* modules/posix_memalign: New file.
* tests/test-stdlib-c++.cc (posix_memalign): Check signature.
* doc/posix-functions/posix_memalign.texi: Mention the new module and
the OpenBSD bug.

1 files changed, 35 insertions, 0 deletions

diff --git a/lib/posix_memalign.c b/lib/posix_memalign.c
new file mode 100644
index 0000000000..ef8576820b
--- /dev/null
+++ b/lib/posix_memalign.c
@@ -0,0 +1,35 @@
+/* A posix_memalign() function that works around platform bugs.
+   Copyright (C) 2020 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 3 of the License, 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 <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <stdlib.h>
+
+#include <errno.h>
+
+int
+posix_memalign (void **memptr, size_t alignment, size_t size)
+#undef posix_memalign
+{
+  /* Round up SIZE to the next multiple of ALIGNMENT, namely
+     (SIZE + ALIGNMENT - 1) & ~(ALIGNMENT - 1).  */
+  size += alignment - 1;
+  if (size >= alignment - 1) /* no overflow? */
+    return posix_memalign (memptr, alignment, size & ~(size_t)(alignment - 1));
+  else
+    return ENOMEM;
+}