--- /dev/null
+/* Test of immutable data.
+ Copyright (C) 2021 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/>. */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2021. */
+
+#include <config.h>
+
+#include "immutable.h"
+
+#include <signal.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "macros.h"
+
+struct data
+{
+ int x;
+ long y;
+};
+
+#if IMMUTABLE_EFFECTIVE
+
+static _GL_ASYNC_SAFE _Noreturn void
+segv_handler (int signo)
+{
+ _Exit (0);
+}
+
+static void
+install_segv_handler (void)
+{
+ signal (SIGSEGV, segv_handler);
+# if defined __APPLE__ && defined __MACH__
+ signal (SIGBUS, segv_handler);
+# endif
+}
+
+#endif
+
+int
+main (int argc, char *argv[])
+{
+ if (argc != 2)
+ {
+ fprintf (stderr, "%s: need 1 argument\n", argv[0]);
+ return 1;
+ }
+ int test = atoi (argv[1]);
+ switch (test)
+ {
+ case 0:
+ /* Indicates whether the implementation effectively rejects writes to
+ immutable data. */
+ #if !IMMUTABLE_EFFECTIVE
+ fputs ("Skipping test: immutability cannot be enforced\n", stderr);
+ return 77;
+ #else
+ break;
+ #endif
+
+ case 1:
+ /* Correct use of immmalloc. */
+ {
+ struct data *wp;
+ struct data const *p;
+
+ wp = (struct data *) immmalloc (sizeof (struct data));
+ ASSERT (wp != NULL);
+ wp->x = 7;
+ wp->y = 42;
+ p = immfreeze (wp);
+ ASSERT (p->x == 7);
+ ASSERT (p->y == 42);
+ immfree (p);
+ }
+ break;
+
+ case 2:
+ /* Catch invalid write access. */
+ {
+ struct data *wp;
+ struct data const *p;
+
+ wp = (struct data *) immmalloc (sizeof (struct data));
+ ASSERT (wp != NULL);
+ wp->x = 7;
+ wp->y = 42;
+ p = immfreeze (wp);
+ #if IMMUTABLE_EFFECTIVE
+ install_segv_handler ();
+ #endif
+ /* This assignment should crash. */
+ ((struct data *) p)->y = 77;
+ #if IMMUTABLE_EFFECTIVE
+ return 1;
+ #endif
+ }
+ break;
+
+ case 3:
+ /* Catch invalid write access while another data object is not frozen. */
+ {
+ struct data *wp;
+ struct data const *p;
+ struct data *wp2;
+
+ wp = (struct data *) immmalloc (sizeof (struct data));
+ ASSERT (wp != NULL);
+ wp->x = 7;
+ wp->y = 42;
+ p = immfreeze (wp);
+ ASSERT (p->x == 7);
+ ASSERT (p->y == 42);
+
+ wp2 = (struct data *) immmalloc (sizeof (struct data));
+ ASSERT (wp2 != NULL);
+ wp2->x = 7;
+ #if IMMUTABLE_EFFECTIVE
+ install_segv_handler ();
+ #endif
+ /* This assignment should crash. */
+ ((struct data *) p)->y = 42;
+ #if IMMUTABLE_EFFECTIVE
+ return 1;
+ #endif
+ }
+ break;
+
+ case 4:
+ /* Correct use of immstrdup. */
+ {
+ const char *s = immstrdup ("Hello");
+ ASSERT (strlen (s) == 5);
+ ASSERT (strcmp (s, "Hello") == 0);
+ immfree (s);
+ }
+ break;
+
+ default:
+ ASSERT (false);
+ }
+ return 0;
+}