Add M4 files to tarball

m4/musl.m4

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+# musl.m4
+# serial 4
+dnl Copyright (C) 2019-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+# Test for musl libc, despite the musl libc authors don't like it
+# <https://wiki.musl-libc.org/faq.html>
+# <https://lists.gnu.org/archive/html/bug-gnulib/2018-02/msg00079.html>.
+# From Bruno Haible.
+
+AC_DEFUN_ONCE([gl_MUSL_LIBC],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  case "$host_os" in
+    *-musl* | midipix*)
+      AC_DEFINE([MUSL_LIBC], [1], [Define to 1 on musl libc.])
+      ;;
+  esac
+])

m4/relocatable-lib.m4

@@ -0,0 +1,51 @@
+# relocatable-lib.m4
+# serial 8
+dnl Copyright (C) 2003, 2005-2007, 2009-2025 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
+
+dnl From Bruno Haible.
+
+dnl Support for relocatable libraries.
+AC_DEFUN([gl_RELOCATABLE_LIBRARY],
+[
+  AC_REQUIRE([gl_RELOCATABLE_LIBRARY_BODY])
+])
+AC_DEFUN([gl_RELOCATABLE_LIBRARY_BODY],
+[
+  AC_REQUIRE([gl_RELOCATABLE_NOP])
+  dnl Easier to put this here once, instead of into the DEFS of each Makefile.
+  if test "X$prefix" = "XNONE"; then
+    reloc_final_prefix="$ac_default_prefix"
+  else
+    reloc_final_prefix="$prefix"
+  fi
+  dnl Define reloc_final_prefix_c and reloc_final_prefix_c_make.
+  gl_BUILD_TO_HOST([reloc_final_prefix])
+  AC_DEFINE_UNQUOTED([INSTALLPREFIX], [${reloc_final_prefix_c}],
+    [Define to the value of ${prefix}, as a string.])
+  if test $RELOCATABLE = yes; then
+    AC_DEFINE([ENABLE_RELOCATABLE], [1],
+      [Define to 1 if the package shall run at any location in the file
+       system.])
+  fi
+])
+
+dnl Support for relocatable packages for which it is a nop.
+AC_DEFUN([gl_RELOCATABLE_NOP],
+[
+  AC_MSG_CHECKING([whether to activate relocatable installation])
+  AC_ARG_ENABLE([relocatable],
+    [AS_HELP_STRING([[--enable-relocatable]],
+      [install a package that can be moved in the file system])],
+    [if test "$enableval" != no; then
+       RELOCATABLE=yes
+     else
+       RELOCATABLE=no
+     fi
+    ], RELOCATABLE=no)
+  AC_SUBST([RELOCATABLE])
+  AC_MSG_RESULT([$RELOCATABLE])
+])

m4/sigaltstack.m4

@@ -0,0 +1,200 @@
+# sigaltstack.m4
+# serial 16
+dnl Copyright (C) 2002-2025 Free Software Foundation, Inc.
+dnl This file is free software, distributed under the terms of the GNU
+dnl General Public License as published by the Free Software Foundation;
+dnl either version 2 of the License, or (at your option) any later version.
+dnl As a special exception to the GNU General Public License, this file
+dnl may be distributed as part of a program that contains a configuration
+dnl script generated by Autoconf, under the same distribution terms as
+dnl the rest of that program.
+
+dnl Written by Bruno Haible and Eric Blake.
+
+AC_DEFUN([SV_SIGALTSTACK],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  AC_CHECK_FUNCS_ONCE([sigaltstack setrlimit])
+
+  if test "$ac_cv_func_sigaltstack" = yes; then
+    AC_CHECK_TYPE([stack_t], ,
+      [AC_DEFINE(stack_t, [struct sigaltstack],
+         [Define to 'struct sigaltstack' if that's the type of the argument to sigaltstack])
+      ],
+      [
+#include <signal.h>
+#if HAVE_SYS_SIGNAL_H
+# include <sys/signal.h>
+#endif
+      ])
+  fi
+
+  AC_CACHE_CHECK([for working sigaltstack], [sv_cv_sigaltstack], [
+    if test "$ac_cv_func_sigaltstack" = yes; then
+      case "$host_os" in
+        macos* | darwin[[6-9]]* | darwin[[1-9]][[0-9]]*)
+          # On MacOS X 10.2 or newer, just assume that if it compiles, it will
+          # work. If we were to perform the real test, 1 Crash Report dialog
+          # window would pop up.
+          AC_LINK_IFELSE([
+            AC_LANG_PROGRAM([[#include <signal.h>]],
+              [[int x = SA_ONSTACK; stack_t ss; sigaltstack ((stack_t*)0, &ss);]])],
+            [sv_cv_sigaltstack="guessing yes"],
+            [sv_cv_sigaltstack=no])
+          ;;
+        *)
+          AC_RUN_IFELSE([
+            AC_LANG_SOURCE([[
+#include <stdlib.h>
+#include <signal.h>
+#if HAVE_SYS_SIGNAL_H
+# include <sys/signal.h>
+#endif
+#if HAVE_SETRLIMIT
+# include <sys/types.h>
+# include <sys/time.h>
+# include <sys/resource.h>
+#endif
+void stackoverflow_handler (int sig)
+{
+  /* If we get here, the stack overflow was caught.  */
+  exit (0);
+}
+volatile int * recurse_1 (volatile int n, volatile int *p)
+{
+  if (n >= 0)
+    *recurse_1 (n + 1, p) += n;
+  return p;
+}
+int recurse (volatile int n)
+{
+  int sum = 0;
+  return *recurse_1 (n, &sum);
+}
+char mystack[2 * (1 << 24)];
+int main ()
+{
+  stack_t altstack;
+  struct sigaction action;
+#if defined HAVE_SETRLIMIT && defined RLIMIT_STACK
+  /* Before starting the endless recursion, try to be friendly to the user's
+     machine.  On some Linux 2.2.x systems, there is no stack limit for user
+     processes at all.  We don't want to kill such systems.  */
+  struct rlimit rl;
+  rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
+  setrlimit (RLIMIT_STACK, &rl);
+#endif
+  /* Install the alternate stack.  Use the midpoint of mystack, to guard
+     against a buggy interpretation of ss_sp on IRIX.  */
+#ifdef SIGSTKSZ
+  if (sizeof mystack / 2 < SIGSTKSZ)
+    exit (3);
+#endif
+  altstack.ss_sp = mystack + sizeof mystack / 2;
+  altstack.ss_size = sizeof mystack / 2;
+  altstack.ss_flags = 0; /* no SS_DISABLE */
+  if (sigaltstack (&altstack, NULL) < 0)
+    exit (1);
+  /* Install the SIGSEGV handler.  */
+  sigemptyset (&action.sa_mask);
+  action.sa_handler = &stackoverflow_handler;
+  action.sa_flags = SA_ONSTACK;
+  sigaction (SIGSEGV, &action, (struct sigaction *) NULL);
+  sigaction (SIGBUS, &action, (struct sigaction *) NULL);
+  /* Provoke a stack overflow.  */
+  recurse (0);
+  exit (2);
+}]])],
+            [sv_cv_sigaltstack=yes],
+            [sv_cv_sigaltstack=no],
+            [
+              dnl FIXME: Put in some more known values here.
+              case "$host_os" in
+                *)
+                  AC_LINK_IFELSE([
+                    AC_LANG_PROGRAM([[#include <signal.h>]],
+                      [[int x = SA_ONSTACK; stack_t ss; sigaltstack ((stack_t*)0, &ss);]])],
+                    [sv_cv_sigaltstack="guessing yes"],
+                    [sv_cv_sigaltstack=no])
+                  ;;
+              esac
+            ])
+          ;;
+      esac
+    else
+      sv_cv_sigaltstack=no
+    fi
+  ])
+  if test "$sv_cv_sigaltstack" != no; then
+    AC_DEFINE([HAVE_WORKING_SIGALTSTACK], [1],
+      [Define if you have the sigaltstack() function and it works.])
+
+    dnl The ss_sp field of a stack_t is, according to POSIX, the lowest address
+    dnl of the memory block designated as an alternate stack. But IRIX 5.3
+    dnl interprets it as the highest address!
+    AC_CACHE_CHECK([for correct stack_t interpretation],
+      [sv_cv_sigaltstack_low_base], [
+      AC_RUN_IFELSE([
+        AC_LANG_SOURCE([[
+#include <stdlib.h>
+#include <signal.h>
+#if HAVE_SYS_SIGNAL_H
+# include <sys/signal.h>
+#endif
+volatile char *stack_lower_bound;
+volatile char *stack_upper_bound;
+static void check_stack_location (volatile char *addr)
+{
+  if (addr >= stack_lower_bound && addr <= stack_upper_bound)
+    exit (0);
+  else
+    exit (1);
+}
+static void stackoverflow_handler (int sig)
+{
+  char dummy;
+  check_stack_location (&dummy);
+}
+char mystack[2 * (1 << 24)];
+int main ()
+{
+  stack_t altstack;
+  struct sigaction action;
+  /* Install the alternate stack.  */
+  altstack.ss_sp = mystack + sizeof mystack / 2;
+  altstack.ss_size = sizeof mystack / 2;
+  stack_lower_bound = (char *) altstack.ss_sp;
+  stack_upper_bound = (char *) altstack.ss_sp + altstack.ss_size - 1;
+  altstack.ss_flags = 0; /* no SS_DISABLE */
+  if (sigaltstack (&altstack, NULL) < 0)
+    exit (2);
+  /* Install the SIGSEGV handler.  */
+  sigemptyset (&action.sa_mask);
+  action.sa_handler = &stackoverflow_handler;
+  action.sa_flags = SA_ONSTACK;
+  if (sigaction (SIGSEGV, &action, (struct sigaction *) NULL) < 0)
+    exit(3);
+  /* Provoke a SIGSEGV.  */
+  raise (SIGSEGV);
+  exit (3);
+}]])],
+      [sv_cv_sigaltstack_low_base=yes],
+      [sv_cv_sigaltstack_low_base=no],
+      [
+        dnl FIXME: Put in some more known values here.
+        case "$host_os" in
+          irix5*) sv_cv_sigaltstack_low_base="no" ;;
+          *)      sv_cv_sigaltstack_low_base="guessing yes" ;;
+        esac
+      ])
+    ])
+    if test "$sv_cv_sigaltstack_low_base" = no; then
+      AC_DEFINE([SIGALTSTACK_SS_REVERSED], [1],
+        [Define if sigaltstack() interprets the stack_t.ss_sp field incorrectly,
+         as the highest address of the alternate stack range rather than as the
+         lowest address.])
+    fi
+  fi
+])