From 5d0926f03527ed236dd045f3ca77f44628fc73a6 Mon Sep 17 00:00:00 2001
From: "Kirill A. Korinsky" <kirill@korins.ky>
Date: Tue, 1 Aug 2023 22:14:06 +0200
Subject: [PATCH] Detect by configure availability of readlinkat

---
 configure      | 8 ++++++++
 configure.in   | 2 ++
 h/gclincl.h.in | 3 +++
 o/unixfsys.c   | 2 +-
 4 files changed, 14 insertions(+), 1 deletion(-)

diff --git configure configure
index 8d086abaa..e10fa1af1 100755
--- configure
+++ configure
@@ -7865,6 +7865,14 @@ else $as_nop
 fi
 
 
+# Not each system has readlinkat
+ac_fn_c_check_func "$LINENO" "readlinkat" "ac_cv_func_readlinkat"
+if test "x$ac_cv_func_readlinkat" = xyes
+then :
+  printf "%s\n" "#define HAVE_READLINKAT 1" >>confdefs.h
+
+fi
+
 
 ac_fn_c_check_header_compile "$LINENO" "sys/ioctl.h" "ac_cv_header_sys_ioctl_h" "$ac_includes_default"
 if test "x$ac_cv_header_sys_ioctl_h" = xyes
diff --git configure.in configure.in
index 4628ea2a0..e4f0a7a92 100644
--- configure.in
+++ configure.in
@@ -1601,6 +1601,8 @@ AC_CHECK_FUNCS(getwd)
 AC_CHECK_FUNC(uname, , AC_DEFINE(NO_UNAME,1,[no uname call]))
 AC_CHECK_FUNC(gettimeofday, , AC_DEFINE(NO_GETTOD))
 
+# Not each system has readlinkat
+AC_CHECK_FUNCS(readlinkat)
 
 AC_CHECK_HEADERS(sys/ioctl.h)
 
diff --git h/gclincl.h.in h/gclincl.h.in
index 343e7ddda..bd16cd438 100644
--- h/gclincl.h.in
+++ h/gclincl.h.in
@@ -183,6 +183,9 @@
 /* Define to 1 if you have the <readline/readline.h> header file. */
 #undef HAVE_READLINE_READLINE_H
 
+/* Define to 1 if you have the `readlinkat' function. */
+#undef HAVE_READLINKAT
+
 /* have readline completion matches */
 #undef HAVE_RL_COMPENTRY_FUNC_T
 
diff --git o/unixfsys.c o/unixfsys.c
index 6e1ea8b8f..ad56e7a7a 100755
--- o/unixfsys.c
+++ o/unixfsys.c
@@ -268,7 +268,7 @@ DEFUN_NEW("READLINKAT",object,fSreadlinkat,SI,2,2,NONE,OI,OO,OO,OO,(fixnum d,obj
   massert(z1<sizeof(FN1));
   memcpy(FN1,s->st.st_self,z1);
   FN1[z1]=0;
-#ifndef __MINGW32__
+#ifdef HAVE_READLINKAT
   massert((l=readlinkat(d ? dirfd((DIR *)d) : AT_FDCWD,FN1,FN2,sizeof(FN2)))>=0 && l<sizeof(FN2));
 #else
   l=0;
-- 
2.41.0