Add a test for longjmp from user context

Verify that longjmp works correctly after setcontext is called to switch
to a user context.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>

2 files changed, 88 insertions, 0 deletions

diff --git a/stdlib/Makefile b/stdlib/Makefile
index 0b154e57c5..8c6249aab4 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -234,6 +234,7 @@ tests := \
   tst-setcontext7 \
   tst-setcontext8 \
   tst-setcontext9 \
+  tst-setcontext10 \
   tst-strfmon_l \
   tst-strfrom \
   tst-strfrom-locale \
diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
new file mode 100644
index 0000000000..2926753cb1
--- /dev/null
+++ b/stdlib/tst-setcontext10.c
@@ -0,0 +1,87 @@
+/* Check longjmp from user context to main context.
+   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 <stdio.h>
+#include <stdlib.h>
+#include <setjmp.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+static jmp_buf jmpbuf;
+static ucontext_t ctx;
+
+static void f2 (void);
+
+static void
+__attribute__ ((noinline, noclone))
+f1 (void)
+{
+  printf ("start f1\n");
+  f2 ();
+}
+
+static void
+__attribute__ ((noinline, noclone))
+f2 (void)
+{
+  printf ("start f2\n");
+  if (setcontext (&ctx) != 0)
+    {
+      printf ("%s: setcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+}
+
+static void
+f3 (void)
+{
+  printf ("start f3\n");
+  longjmp (jmpbuf, 1);
+}
+
+static int
+__attribute__ ((noinline, noclone))
+do_test_1 (void)
+{
+  char st1[32768];
+
+  if (setjmp (jmpbuf) != 0)
+    return 0;
+
+  puts ("making contexts");
+  if (getcontext (&ctx) != 0)
+    {
+      printf ("%s: getcontext: %m\n", __FUNCTION__);
+      exit (EXIT_FAILURE);
+    }
+  ctx.uc_stack.ss_sp = st1;
+  ctx.uc_stack.ss_size = sizeof st1;
+  ctx.uc_link = NULL;
+  makecontext (&ctx, (void (*) (void)) f3, 0);
+  f1 ();
+  puts ("FAIL: returned from f1 ()");
+  exit (EXIT_FAILURE);
+}
+
+static int
+do_test (void)
+{
+  return do_test_1 ();
+}
+
+#include <support/test-driver.c>