[glibc] tst-setcontext10.c: Undef _FORTIFY_SOURCE

[glibc] tst-setcontext10.c: Undef _FORTIFY_SOURCE

[H.J. Lu]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=46432be2f1d4de962b51ca6b9f80fc37744be9f7

commit 46432be2f1d4de962b51ca6b9f80fc37744be9f7
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Tue Dec 19 09:55:25 2023 -0800

    tst-setcontext10.c: Undef _FORTIFY_SOURCE
    
    When _FORTIFY_SOURCE is defined to 2, ____longjmp_chk is called,
    instead of longjmp.  ____longjmp_chk compares the relative stack
    values to decide if it is called from a stack frame which called
    setjmp.  If not, ____longjmp_chk assumes that an alternate signal
    stack is used.  Since comparing the relative stack values isn't
    reliable with user context, when there is no signal, ____longjmp_chk
    will fail.  Undefine _FORTIFY_SOURCE to avoid ____longjmp_chk in
    user context test.

Diff:
---
 stdlib/tst-setcontext10.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/stdlib/tst-setcontext10.c b/stdlib/tst-setcontext10.c
index 2926753cb1..d714563742 100644
--- a/stdlib/tst-setcontext10.c
+++ b/stdlib/tst-setcontext10.c
@@ -16,6 +16,15 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+/* When _FORTIFY_SOURCE is defined to 2, ____longjmp_chk is called,
+   instead of longjmp.  ____longjmp_chk compares the relative stack
+   values to decide if it is called from a stack frame which called
+   setjmp.  If not, ____longjmp_chk assumes that an alternate signal
+   stack is used.  Since comparing the relative stack values isn't
+   reliable with user context, when there is no signal, ____longjmp_chk
+   will fail.  Undefine _FORTIFY_SOURCE to avoid ____longjmp_chk.  */
+#undef _FORTIFY_SOURCE
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <setjmp.h>