From 0e62a6742bca186624e97e2121c98ada30e009a0 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Thu, 25 Feb 2021 17:17:56 +0100
Subject: [PATCH 4236/5000] patch 8.2.2550: signal stack size is wrong with
 latest glibc 2.34

Problem:    Signal stack size is wrong with latest glibc 2.34.
Solution:   Use sysconf(_SC_SIGSTKSZ) if available. (Zdenek Dohnal, closes
            #7895)
---
 src/auto/configure | 24 ++++++++++++++++++++++++
 src/config.h.in    |  3 +++
 src/configure.ac   |  9 +++++++++
 src/os_unix.c      | 14 +++++++++++++-
 4 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/auto/configure b/src/auto/configure
index 250e5ae..8183499 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -13943,6 +13943,30 @@ $as_echo "not usable" >&6; }
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for _SC_SIGSTKSZ via sysconf()" >&5
+$as_echo_n "checking for _SC_SIGSTKSZ via sysconf()... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <unistd.h>
+int
+main ()
+{
+	(void)sysconf(_SC_SIGSTKSZ);
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }; $as_echo "#define HAVE_SYSCONF_SIGSTKSZ 1" >>confdefs.h
+
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: not usable" >&5
+$as_echo "not usable" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
 # The cast to long int works around a bug in the HP C Compiler
 # version HP92453-01 B.11.11.23709.GP, which incorrectly rejects
 # declarations like `int a3[[(sizeof (unsigned char)) >= 0]];'.
diff --git a/src/config.h.in b/src/config.h.in
index b114480..5d01e2c 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -496,3 +496,6 @@
 
 /* Define to inline symbol or empty */
 #undef inline
+
+/* Define if _SC_SIGSTKSZ is available via sysconf() */
+#undef HAVE_SYSCONF_SIGSTKSZ
diff --git a/src/configure.ac b/src/configure.ac
index 58bfa19..798e9b8 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -4105,6 +4105,15 @@ AC_TRY_COMPILE(
 	AC_MSG_RESULT(yes); AC_DEFINE(HAVE_SYSCONF),
 	AC_MSG_RESULT(not usable))
 
+dnl check if we have _SC_SIGSTKSZ via sysconf()
+AC_MSG_CHECKING(for _SC_SIGSTKSZ via sysconf())
+AC_TRY_COMPILE(
+[#include <unistd.h>],
+[	(void)sysconf(_SC_SIGSTKSZ);
+	],
+	AC_MSG_RESULT(yes); AC_DEFINE(HAVE_SYSCONF_SIGSTKSZ),
+	AC_MSG_RESULT(not usable))
+
 AC_CHECK_SIZEOF([int])
 AC_CHECK_SIZEOF([long])
 AC_CHECK_SIZEOF([time_t])
diff --git a/src/os_unix.c b/src/os_unix.c
index 1edc7e6..1c80799 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -783,7 +783,7 @@ mch_stackcheck(char *p)
  * completely full.
  */
 
-#ifndef SIGSTKSZ
+#if !defined SIGSTKSZ && !defined(HAVE_SYSCONF_SIGSTKSZ)
 # define SIGSTKSZ 8000    // just a guess of how much stack is needed...
 #endif
 
@@ -806,13 +806,21 @@ init_signal_stack(void)
 #  else
 	sigstk.ss_sp = signal_stack;
 #  endif
+#  ifdef HAVE_SYSCONF_SIGSTKSZ
+	sigstk.ss_size = sysconf(_SC_SIGSTKSZ);
+#  else
 	sigstk.ss_size = SIGSTKSZ;
+#  endif
 	sigstk.ss_flags = 0;
 	(void)sigaltstack(&sigstk, NULL);
 # else
 	sigstk.ss_sp = signal_stack;
 	if (stack_grows_downwards)
+#  ifdef HAVE_SYSCONF_SIGSTKSZ
+	    sigstk.ss_sp += sysconf(_SC_SIGSTKSZ) - 1;
+#  else
 	    sigstk.ss_sp += SIGSTKSZ - 1;
+#  endif
 	sigstk.ss_onstack = 0;
 	(void)sigstack(&sigstk, NULL);
 # endif
@@ -3261,7 +3269,11 @@ mch_early_init(void)
      * Ignore any errors.
      */
 #if defined(HAVE_SIGALTSTACK) || defined(HAVE_SIGSTACK)
+# ifdef HAVE_SYSCONF_SIGSTKSZ
+    signal_stack = alloc(sysconf(_SC_SIGSTKSZ));
+# else
     signal_stack = alloc(SIGSTKSZ);
+# endif
     init_signal_stack();
 #endif
 }
-- 
1.8.3.1

