Update configure's probe for libldap to work with OpenLDAP 2.5.

The separate libldap_r is gone and libldap itself is now always
thread-safe.  Unfortunately there seems no easy way to tell by
inspection whether libldap is thread-safe, so we have to take
it on faith that libldap is thread-safe if there's no libldap_r.
That should be okay, as it appears that libldap_r was a standard
part of the installation going back at least 20 years.

Report and patch by Adrian Ho.  Back-patch to all supported
branches, since people might try to build any of them with
a newer OpenLDAP.

Discussion: https://postgr.es/m/17083-a19190d9591946a7@postgresql.org

configure

@@ -12880,13 +12880,17 @@ fi
 if test "$with_ldap" = yes ; then
   _LIBS="$LIBS"
   if test "$PORTNAME" != "win32"; then
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ldap_bind in -lldap" >&5
-$as_echo_n "checking for ldap_bind in -lldap... " >&6; }
-if ${ac_cv_lib_ldap_ldap_bind+:} false; then :
+    if test "$enable_thread_safety" = yes; then
+      # Use ldap_r for FE if available, else assume ldap is thread-safe.
+      # If ldap_r does exist, assume without checking that ldap does too.
+      # on some platforms ldap_r fails to link without PTHREAD_LIBS
+      LIBS=""
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing ldap_bind" >&5
+$as_echo_n "checking for library containing ldap_bind... " >&6; }
+if ${ac_cv_search_ldap_bind+:} false; then :
   $as_echo_n "(cached) " >&6
 else
-  ac_check_lib_save_LIBS=$LIBS
-LIBS="-lldap $EXTRA_LDAP_LIBS $LIBS"
+  ac_func_search_save_LIBS=$LIBS
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -12905,38 +12909,50 @@ return ldap_bind ();
   return 0;
 }
 _ACEOF
-if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_ldap_ldap_bind=yes
-else
-  ac_cv_lib_ldap_ldap_bind=no
+for ac_lib in '' ldap_r ldap; do
+  if test -z "$ac_lib"; then
+    ac_res="none required"
+  else
+    ac_res=-l$ac_lib
+    LIBS="-l$ac_lib $PTHREAD_CFLAGS $PTHREAD_LIBS $EXTRA_LDAP_LIBS $ac_func_search_save_LIBS"
+  fi
+  if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_search_ldap_bind=$ac_res
 fi
 rm -f core conftest.err conftest.$ac_objext \
-    conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
+    conftest$ac_exeext
+  if ${ac_cv_search_ldap_bind+:} false; then :
+  break
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_ldap_ldap_bind" >&5
-$as_echo "$ac_cv_lib_ldap_ldap_bind" >&6; }
-if test "x$ac_cv_lib_ldap_ldap_bind" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_LIBLDAP 1
-_ACEOF
+done
+if ${ac_cv_search_ldap_bind+:} false; then :
 
-  LIBS="-lldap $LIBS"
+else
+  ac_cv_search_ldap_bind=no
+fi
+rm conftest.$ac_ext
+LIBS=$ac_func_search_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_search_ldap_bind" >&5
+$as_echo "$ac_cv_search_ldap_bind" >&6; }
+ac_res=$ac_cv_search_ldap_bind
+if test "$ac_res" != no; then :
+  test "$ac_res" = "none required" || LIBS="$ac_res $LIBS"
 
 else
   as_fn_error $? "library 'ldap' is required for LDAP" "$LINENO" 5
 fi
 
-    LDAP_LIBS_BE="-lldap $EXTRA_LDAP_LIBS"
-    if test "$enable_thread_safety" = yes; then
-      # on some platforms ldap_r fails to link without PTHREAD_LIBS
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ldap_simple_bind in -lldap_r" >&5
-$as_echo_n "checking for ldap_simple_bind in -lldap_r... " >&6; }
-if ${ac_cv_lib_ldap_r_ldap_simple_bind+:} false; then :
+      LDAP_LIBS_FE="$LIBS $EXTRA_LDAP_LIBS"
+      LDAP_LIBS_BE="-lldap $EXTRA_LDAP_LIBS"
+    else
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ldap_bind in -lldap" >&5
+$as_echo_n "checking for ldap_bind in -lldap... " >&6; }
+if ${ac_cv_lib_ldap_ldap_bind+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lldap_r $PTHREAD_CFLAGS $PTHREAD_LIBS $EXTRA_LDAP_LIBS $LIBS"
+LIBS="-lldap $EXTRA_LDAP_LIBS $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -12946,40 +12962,39 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char ldap_simple_bind ();
+char ldap_bind ();
 int
 main ()
 {
-return ldap_simple_bind ();
+return ldap_bind ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_ldap_r_ldap_simple_bind=yes
+  ac_cv_lib_ldap_ldap_bind=yes
 else
-  ac_cv_lib_ldap_r_ldap_simple_bind=no
+  ac_cv_lib_ldap_ldap_bind=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_ldap_r_ldap_simple_bind" >&5
-$as_echo "$ac_cv_lib_ldap_r_ldap_simple_bind" >&6; }
-if test "x$ac_cv_lib_ldap_r_ldap_simple_bind" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_ldap_ldap_bind" >&5
+$as_echo "$ac_cv_lib_ldap_ldap_bind" >&6; }
+if test "x$ac_cv_lib_ldap_ldap_bind" = xyes; then :
   cat >>confdefs.h <<_ACEOF
-#define HAVE_LIBLDAP_R 1
+#define HAVE_LIBLDAP 1
 _ACEOF
 
-  LIBS="-lldap_r $LIBS"
+  LIBS="-lldap $LIBS"
 
 else
-  as_fn_error $? "library 'ldap_r' is required for LDAP" "$LINENO" 5
+  as_fn_error $? "library 'ldap' is required for LDAP" "$LINENO" 5
 fi
 
-      LDAP_LIBS_FE="-lldap_r $EXTRA_LDAP_LIBS"
-    else
       LDAP_LIBS_FE="-lldap $EXTRA_LDAP_LIBS"
+      LDAP_LIBS_BE="-lldap $EXTRA_LDAP_LIBS"
     fi
     for ac_func in ldap_initialize
 do :

configure.ac

@@ -1289,18 +1289,22 @@ fi
 if test "$with_ldap" = yes ; then
   _LIBS="$LIBS"
   if test "$PORTNAME" != "win32"; then
-    AC_CHECK_LIB(ldap, ldap_bind, [],
-		 [AC_MSG_ERROR([library 'ldap' is required for LDAP])],
-		 [$EXTRA_LDAP_LIBS])
-    LDAP_LIBS_BE="-lldap $EXTRA_LDAP_LIBS"
     if test "$enable_thread_safety" = yes; then
+      # Use ldap_r for FE if available, else assume ldap is thread-safe.
+      # If ldap_r does exist, assume without checking that ldap does too.
       # on some platforms ldap_r fails to link without PTHREAD_LIBS
-      AC_CHECK_LIB(ldap_r, ldap_simple_bind, [],
-		   [AC_MSG_ERROR([library 'ldap_r' is required for LDAP])],
-		   [$PTHREAD_CFLAGS $PTHREAD_LIBS $EXTRA_LDAP_LIBS])
-      LDAP_LIBS_FE="-lldap_r $EXTRA_LDAP_LIBS"
+      LIBS=""
+      AC_SEARCH_LIBS(ldap_bind, [ldap_r ldap], [],
+                     [AC_MSG_ERROR([library 'ldap' is required for LDAP])],
+                     [$PTHREAD_CFLAGS $PTHREAD_LIBS $EXTRA_LDAP_LIBS])
+      LDAP_LIBS_FE="$LIBS $EXTRA_LDAP_LIBS"
+      LDAP_LIBS_BE="-lldap $EXTRA_LDAP_LIBS"
     else
+      AC_CHECK_LIB(ldap, ldap_bind, [],
+                   [AC_MSG_ERROR([library 'ldap' is required for LDAP])],
+                   [$EXTRA_LDAP_LIBS])
       LDAP_LIBS_FE="-lldap $EXTRA_LDAP_LIBS"
+      LDAP_LIBS_BE="-lldap $EXTRA_LDAP_LIBS"
     fi
     AC_CHECK_FUNCS([ldap_initialize])
   else

src/include/pg_config.h.in

@@ -322,9 +322,6 @@
 /* Define to 1 if you have the `ldap' library (-lldap). */
 #undef HAVE_LIBLDAP
 
-/* Define to 1 if you have the `ldap_r' library (-lldap_r). */
-#undef HAVE_LIBLDAP_R
-
 /* Define to 1 if you have the `lz4' library (-llz4). */
 #undef HAVE_LIBLZ4
 

src/tools/msvc/Solution.pm

@@ -302,7 +302,6 @@ sub GenerateFiles
 		HAVE_LDAP_INITIALIZE                        => undef,
 		HAVE_LIBCRYPTO                              => undef,
 		HAVE_LIBLDAP                                => undef,
-		HAVE_LIBLDAP_R                              => undef,
 		HAVE_LIBLZ4                                 => undef,
 		HAVE_LIBM                                   => undef,
 		HAVE_LIBPAM                                 => undef,