1 files changed, 69 insertions, 0 deletions
diff --git a/signal/tst-minsigstksz-3a.c b/signal/tst-minsigstksz-3a.c
new file mode 100644
index 0000000000..b58b8d01ba
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+++ b/signal/tst-minsigstksz-3a.c
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+/* Tests of signal delivery on an alternate stack (_exit).
+   Copyright (C) 2019 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsignal.h>
+#include <support/support.h>
+#include <support/check.h>
+#include <unistd.h>
+
+/* C2011 7.4.1.1p5 specifies that only the following operations are
+   guaranteed to be well-defined inside an asynchronous signal handler:
+     * any operation on a lock-free atomic object
+     * assigning a value to an object declared as volatile sig_atomic_t
+     * calling abort, _Exit, quick_exit, or signal
+       * signal may only be called with its first argument equal to the
+         number of the signal that caused the handler to be called
+
+   We use this list as a guideline for the set of operations that ought
+   also to be safe in a _synchronous_ signal delivered on an alternate
+   signal stack with only MINSIGSTKSZ bytes of space.
+
+   This test program tests calls to _exit, which is the same function
+   as _Exit, but specified by POSIX rather than ISO C.  For reasons
+   unknown to the author of this program, the C committee did not
+   think it could standardize _exit under that name; regardless, in a
+   POSIX-conformant environment, they should be completely
+   interchangeable.  */
+
+#define EXPECTED_STATUS 3
+
+static void
+handler (int unused)
+{
+  _exit (EXPECTED_STATUS);
+}
+
+int
+do_test (void)
+{
+  void *sstk = xalloc_sigstack (0);
+  struct sigaction sa;
+
+  sa.sa_handler = handler;
+  sa.sa_flags   = SA_RESTART | SA_ONSTACK;
+  sigfillset (&sa.sa_mask);
+  if (sigaction (SIGUSR1, &sa, 0))
+    FAIL_RET ("sigaction (SIGUSR1, handler): %m\n");
+
+  raise (SIGUSR1);
+
+  xfree_sigstack (sstk);
+  FAIL_RET ("test process was not terminated by _exit in signal handler");
+}
+
+#include <support/test-driver.c>