With the glibc header files from a current glibc (post 2.33) and
CC="gcc -I$GLIBC_INSTALL_PREFIX/include -D_GNU_SOURCE", I get this
compilation error in a test of module 'sigsegv':
In file included from ../../gltests/test-sigsegv-catch-stackoverflow1.c:44:0:
../../gltests/altstack-util.h:32:6: error: variably modified ‘mystack_storage’
at file scope
char mystack_storage[SIGSTKSZ + 2 * MYSTACK_CRUMPLE_ZONE + 31];
^
Similarly, the autoconf tests of the modules 'sigsegv' and 'c-stack'
have guessed wrong.
The cause is that in glibc, SIGSTKSZ is no longer a compile-time constant.
The discussion in March 2021
<https://sourceware.org/pipermail/libc-alpha/2021-March/123553.html>
only had the effect that the change was limited to the case that _GNU_SOURCE
is enabled. But we are compiling nearly all programs with _GNU_SOURCE=1.
I don't have time to rewrite all these unit tests and autoconf tests.
(Additionally, if we were to use malloc() as a replacement, watch out
that malloc()ed memory may not be executable, but some programs need
an executable stack.)
Instead, just use a constant. Which constant is appropriate? glibc-2.33
has these definitions:
glibc-2.33/sysdeps/unix/sysv/linux/sparc/bits/sigstack.h:#define SIGSTKSZ
16384
glibc-2.33/sysdeps/unix/sysv/linux/powerpc/bits/sigstack.h:#define SIGSTKSZ
16384
glibc-2.33/sysdeps/unix/sysv/linux/ia64/bits/sigstack.h:#define SIGSTKSZ
262144
glibc-2.33/sysdeps/unix/sysv/linux/bits/sigstack.h:#define SIGSTKSZ 8192
glibc-2.33/sysdeps/unix/sysv/linux/alpha/bits/sigstack.h:#define SIGSTKSZ
16384
glibc-2.33/sysdeps/unix/sysv/linux/aarch64/bits/sigstack.h:#define SIGSTKSZ
16384
glibc-2.33/bits/sigstack.h:#define SIGSTKSZ (MINSIGSTKSZ + 32768)
glibc-2.33/bits/sigstack.h:#define MINSIGSTKSZ 8192
So, basically, 256 KB on ia64 and 40 KB (or 64 KB) on all other architectures
should be sufficient. Although there never can be a true guarantee regarding
future processors.
This patch fixes the things from the gnulib side.
2021-05-16 Bruno Haible <br...@clisp.org>
sigsegv, c-stack: Avoid compilation error with glibc >= 2.34.
* lib/sigsegv.in.h (SIGSTKSZ): On glibc systems, redefine to a suitable
constant.
* m4/sigaltstack.m4 (SV_SIGALTSTACK): Likewise.
* m4/c-stack.m4 (AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC): Likewise.
diff --git a/lib/sigsegv.in.h b/lib/sigsegv.in.h
index 1c87acc..e442f4d 100644
--- a/lib/sigsegv.in.h
+++ b/lib/sigsegv.in.h
@@ -37,16 +37,25 @@
#endif
/* Correct the value of SIGSTKSZ on some systems.
+ glibc >= 2.34: When _GNU_SOURCE is defined, SIGSTKSZ is no longer a
+ compile-time constant. But most programs need a simple constant.
AIX 64-bit: original value 4096 is too small.
HP-UX: original value 8192 is too small.
Solaris 11/x86_64: original value 8192 is too small. */
+#include <signal.h>
+#if __GLIBC__ >= 2
+# undef SIGSTKSZ
+# if defined __ia64__
+# define SIGSTKSZ 262144
+# else
+# define SIGSTKSZ 65536
+# endif
+#endif
#if defined _AIX && defined _ARCH_PPC64
-# include <signal.h>
# undef SIGSTKSZ
# define SIGSTKSZ 8192
#endif
#if defined __hpux || (defined __sun && (defined __x86_64__ || defined
__amd64__))
-# include <signal.h>
# undef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
diff --git a/m4/c-stack.m4 b/m4/c-stack.m4
index 06b2594..3131dd5 100644
--- a/m4/c-stack.m4
+++ b/m4/c-stack.m4
@@ -7,7 +7,7 @@
# Written by Paul Eggert.
-# serial 21
+# serial 22
AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC],
[
@@ -44,6 +44,17 @@ AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC],
# include <sys/time.h>
# include <sys/resource.h>
#endif
+ /* In glibc >= 2.34, when _GNU_SOURCE is defined, SIGSTKSZ is
+ no longer a compile-time constant. But we need a simple
+ constant here. */
+ #if __GLIBC__ >= 2
+ # undef SIGSTKSZ
+ # if defined __ia64__
+ # define SIGSTKSZ 262144
+ # else
+ # define SIGSTKSZ 16384
+ # endif
+ #endif
#ifndef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
@@ -149,6 +160,16 @@ AC_DEFUN([AC_SYS_XSI_STACK_OVERFLOW_HEURISTIC],
#if HAVE_SYS_SIGNAL_H
# include <sys/signal.h>
#endif
+/* In glibc >= 2.34, when _GNU_SOURCE is defined, SIGSTKSZ is no longer a
+ compile-time constant. But we need a simple constant here. */
+#if __GLIBC__ >= 2
+# undef SIGSTKSZ
+# if defined __ia64__
+# define SIGSTKSZ 262144
+# else
+# define SIGSTKSZ 16384
+# endif
+#endif
#ifndef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
@@ -233,6 +254,17 @@ int main ()
# include <sys/time.h>
# include <sys/resource.h>
#endif
+ /* In glibc >= 2.34, when _GNU_SOURCE is defined, SIGSTKSZ is
+ no longer a compile-time constant. But we need a simple
+ constant here. */
+ #if __GLIBC__ >= 2
+ # undef SIGSTKSZ
+ # if defined __ia64__
+ # define SIGSTKSZ 262144
+ # else
+ # define SIGSTKSZ 16384
+ # endif
+ #endif
#ifndef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
diff --git a/m4/sigaltstack.m4 b/m4/sigaltstack.m4
index 212e9d3..837191e 100644
--- a/m4/sigaltstack.m4
+++ b/m4/sigaltstack.m4
@@ -1,4 +1,4 @@
-# sigaltstack.m4 serial 12
+# sigaltstack.m4 serial 13
dnl Copyright (C) 2002-2021 Bruno Haible <br...@clisp.org>
dnl Copyright (C) 2008 Eric Blake <e...@byu.net>
dnl This file is free software, distributed under the terms of the GNU
@@ -53,6 +53,16 @@ AC_DEFUN([SV_SIGALTSTACK],
# include <sys/time.h>
# include <sys/resource.h>
#endif
+/* In glibc >= 2.34, when _GNU_SOURCE is defined, SIGSTKSZ is no longer a
+ compile-time constant. But we need a simple constant here. */
+#if __GLIBC__ >= 2
+# undef SIGSTKSZ
+# if defined __ia64__
+# define SIGSTKSZ 262144
+# else
+# define SIGSTKSZ 16384
+# endif
+#endif
#ifndef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
@@ -138,6 +148,16 @@ int main ()
#if HAVE_SYS_SIGNAL_H
# include <sys/signal.h>
#endif
+/* In glibc >= 2.34, when _GNU_SOURCE is defined, SIGSTKSZ is no longer a
+ compile-time constant. But we need a simple constant here. */
+#if __GLIBC__ >= 2
+# undef SIGSTKSZ
+# if defined __ia64__
+# define SIGSTKSZ 262144
+# else
+# define SIGSTKSZ 16384
+# endif
+#endif
#ifndef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
