1 files changed, 64 insertions, 0 deletions
diff --git a/support/support_mem_access.c b/support/support_mem_access.c
new file mode 100644
index 0000000..e5a1666
--- /dev/null
+++ b/support/support_mem_access.c
@@ -0,0 +1,64 @@
+/* Implementation of the test verification functions for memory access
+   checks.
+   Copyright (C) 2025 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 <setjmp.h>
+#include <signal.h>
+#include <stddef.h>
+#include <support/xsignal.h>
+
+#include "check_mem_access.h"
+
+static sigjmp_buf sigsegv_jmp_buf;
+
+static void
+__sigsegv_handler (int signum)
+{
+  siglongjmp (sigsegv_jmp_buf, signum);
+}
+
+bool check_mem_access (const void *addr, bool write)
+{
+  /* This is obviously not thread-safe.  */
+  static bool handler_set_up;
+  if (!handler_set_up)
+    {
+      struct sigaction sa = {
+	.sa_handler = __sigsegv_handler,
+	.sa_flags = SA_NODEFER,
+      };
+      sigemptyset (&sa.sa_mask);
+      xsigaction (SIGSEGV, &sa, NULL);
+      /* Some system generates SIGBUS accessing the guard area when it is
+	 setup with madvise.  */
+      xsigaction (SIGBUS, &sa, NULL);
+      handler_set_up = true;
+    }
+  int r = sigsetjmp (sigsegv_jmp_buf, 0);
+  if (r == 0)
+    {
+      if (write)
+        *(volatile char *)addr = 'x';
+      else
+        *(volatile char *)addr;
+      return true;
+    }
+  if (r == SIGSEGV || r == SIGBUS)
+    return false;
+  return true;
+}