aligned_alloc: conform to C17

This patch adds the strict checking for power-of-two alignments
in aligned_alloc(), and updates the manual accordingly.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/malloc/tst-aligned-alloc.c b/malloc/tst-aligned-alloc.c
new file mode 100644
index 0000000..8bd6527
--- /dev/null
+++ b/malloc/tst-aligned-alloc.c
@@ -0,0 +1,80 @@
+/* Test for C17 alignment requirements.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library 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.
+
+   The GNU C Library 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 the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <malloc.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libc-diag.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  void *p1;
+  void *p2;
+  void *p3;
+  void *p4;
+  void *p5;
+
+  errno = 0;
+
+  /* The implementation supports alignments that are non-negative powers of 2.
+     We test 5 distinct conditions here:
+     - A non-negative power of 2 alignment e.g. 64.
+     - A degenerate zero power of 2 alignment e.g. 1.
+     - A non-power-of-2 alignment e.g. 65.
+     - A zero alignment.
+     - A corner case SIZE_MAX / 2 + 1 alignment.
+  */
+
+  p1 = aligned_alloc (64, 64);
+
+  if (p1 == NULL)
+    FAIL_EXIT1 ("aligned_alloc(64, 64) failed");
+
+  p2 = aligned_alloc (1, 64);
+
+  if (p2 == NULL)
+    FAIL_EXIT1 ("aligned_alloc(1, 64) failed");
+
+  p3 = aligned_alloc (65, 64);
+
+  if (p3 != NULL)
+    FAIL_EXIT1 ("aligned_alloc(65, 64) did not fail");
+
+  p4 = aligned_alloc (0, 64);
+
+  if (p4 != NULL)
+    FAIL_EXIT1 ("aligned_alloc(0, 64) did not fail");
+
+  /* This is an alignment like 0x80000000...UL */
+  p5 = aligned_alloc (SIZE_MAX / 2 + 1, 64);
+
+  if (p5 != NULL)
+    FAIL_EXIT1 ("aligned_alloc(SIZE_MAX/2+1, 64) did not fail");
+
+  free (p1);
+  free (p2);
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"