1From f97e07ea807cc6d38774a3888a15091b20645ac6 Mon Sep 17 00:00:00 2001 2From: Paul Eggert <eggert@cs.ucla.edu> 3Date: Tue, 9 Mar 2021 11:22:59 -0800 4Subject: [PATCH] Port alternate signal stack to upcoming glibc 2.34 5MIME-Version: 1.0 6Content-Type: text/plain; charset=UTF-8 7Content-Transfer-Encoding: 8bit 8 9* src/sysdep.c (sigsegv_stack): Increase size to 64 KiB and align 10it to max_align_t. This copies from Gnulib’s c-stack.c, and works 11around a portability bug in draft glibc 2.34, which no longer 12defines SIGSTKSZ when _GNU_SOURCE is defined. 13--- 14 src/sysdep.c | 10 +++++++++- 15 1 file changed, 9 insertions(+), 1 deletion(-) 16 17diff --git a/src/sysdep.c b/src/sysdep.c 18index 941b4e2fa2..24d8832b2f 100644 19--- a/src/sysdep.c 20+++ b/src/sysdep.c 21@@ -1785,7 +1785,15 @@ handle_arith_signal (int sig) 22 23 /* Alternate stack used by SIGSEGV handler below. */ 24 25-static unsigned char sigsegv_stack[SIGSTKSZ]; 26+/* Storage for the alternate signal stack. 27+ 64 KiB is not too large for Emacs, and is large enough 28+ for all known platforms. Smaller sizes may run into trouble. 29+ For example, libsigsegv 2.6 through 2.8 have a bug where some 30+ architectures use more than the Linux default of an 8 KiB alternate 31+ stack when deciding if a fault was caused by stack overflow. */ 32+static max_align_t sigsegv_stack[(64 * 1024 33+ + sizeof (max_align_t) - 1) 34+ / sizeof (max_align_t)]; 35 36 37 /* Return true if SIGINFO indicates a stack overflow. */ 38-- 392.29.2 40 41