Fix FTBFS with glibc 2.34

Source: https://src.fedoraproject.org/rpms/emacs.git#181aafcdb7ee2fded9fce4cfc448f27edccc927f

Resolves: #1975151

emacs-glibc-2.34.patch

@@ -0,0 +1,40 @@
+From f97e07ea807cc6d38774a3888a15091b20645ac6 Mon Sep 17 00:00:00 2001
+From: Paul Eggert <eggert@cs.ucla.edu>
+Date: Tue, 9 Mar 2021 11:22:59 -0800
+Subject: [PATCH] Port alternate signal stack to upcoming glibc 2.34
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+* src/sysdep.c (sigsegv_stack): Increase size to 64 KiB and align
+it to max_align_t.  This copies from Gnulib’s c-stack.c, and works
+around a portability bug in draft glibc 2.34, which no longer
+defines SIGSTKSZ when _GNU_SOURCE is defined.
+---
+ src/sysdep.c | 10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+diff --git a/src/sysdep.c b/src/sysdep.c
+index 941b4e2fa2..24d8832b2f 100644
+--- a/src/sysdep.c
++++ b/src/sysdep.c
+@@ -1785,7 +1785,15 @@ handle_arith_signal (int sig)
+ 
+ /* Alternate stack used by SIGSEGV handler below.  */
+ 
+-static unsigned char sigsegv_stack[SIGSTKSZ];
++/* Storage for the alternate signal stack.
++   64 KiB is not too large for Emacs, and is large enough
++   for all known platforms.  Smaller sizes may run into trouble.
++   For example, libsigsegv 2.6 through 2.8 have a bug where some
++   architectures use more than the Linux default of an 8 KiB alternate
++   stack when deciding if a fault was caused by stack overflow.  */
++static max_align_t sigsegv_stack[(64 * 1024
++				  + sizeof (max_align_t) - 1)
++				 / sizeof (max_align_t)];
+ 
+ 
+ /* Return true if SIGINFO indicates a stack overflow.  */
+-- 
+2.29.2
+

emacs.spec

@@ -5,7 +5,7 @@ Summary:       GNU Emacs text editor
 Name:          emacs
 Epoch:         1
 Version:       27.2
-Release:       3%{?dist}
+Release:       4%{?dist}
 License:       GPLv3+ and CC0-1.0
 URL:           http://www.gnu.org/software/emacs/
 Source0:       https://ftp.gnu.org/gnu/emacs/emacs-%{version}.tar.xz
@@ -26,6 +26,7 @@ Source10:      %{name}.appdata.xml
 # rhbz#713600
 Patch1:        emacs-spellchecker.patch
 Patch2:        emacs-system-crypto-policies.patch
+Patch3:        emacs-glibc-2.34.patch
 
 BuildRequires: gcc
 BuildRequires: atk-devel
@@ -188,6 +189,7 @@ Development header files for Emacs.
 
 %patch1 -p1 -b .spellchecker
 %patch2 -p1 -b .system-crypto-policies
+%patch3 -p1 -b .glibc2.34
 autoconf
 
 # We prefer our emacs.desktop file
@@ -482,6 +484,9 @@ rm %{buildroot}%{_datadir}/icons/hicolor/scalable/mimetypes/emacs-document23.svg
 %{_includedir}/emacs-module.h
 
 %changelog
+* Tue Aug 10 2021 Jacek Migacz <jmigacz@redhat.com> - 1:27.2-4
+- Fix FTBFS with glibc 2.34 (#1975151)
+
 * Mon Aug 09 2021 Mohan Boddu <mboddu@redhat.com> - 1:27.2-3
 - Rebuilt for IMA sigs, glibc 2.34, aarch64 flags
   Related: rhbz#1991688