X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/2238127283d703f38765f9b3f6a64f799d18e9e5..3191b52fa869eeb664e3c3c11c1a21a1f1127782:/m4/dup2.m4

diff --git a/m4/dup2.m4 b/m4/dup2.m4
index 8d7f62c887..269cfdc112 100644
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,5 +1,5 @@
-#serial 13
-dnl Copyright (C) 2002, 2005, 2007, 2009-2011 Free Software Foundation, Inc.
+#serial 19
+dnl Copyright (C) 2002, 2005, 2007, 2009-2013 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.
@@ -12,7 +12,6 @@ AC_DEFUN([gl_FUNC_DUP2],
     AC_CHECK_FUNCS_ONCE([dup2])
     if test $ac_cv_func_dup2 = no; then
       HAVE_DUP2=0
-      AC_LIBOBJ([dup2])
     fi
   ], [
     AC_DEFINE([HAVE_DUP2], [1], [Define to 1 if you have the 'dup2' function.])
@@ -40,37 +39,46 @@ AC_DEFUN([gl_FUNC_DUP2],
             /* Many gnulib modules require POSIX conformance of EBADF.  */
             if (dup2 (2, 1000000) == -1 && errno != EBADF)
               result |= 16;
+            /* Flush out a cygwin core dump.  */
+            if (dup2 (2, -1) != -1 || errno != EBADF)
+              result |= 32;
             return result;
            ])
         ],
         [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
         [case "$host_os" in
            mingw*) # on this platform, dup2 always returns 0 for success
-             gl_cv_func_dup2_works=no;;
+             gl_cv_func_dup2_works="guessing no" ;;
            cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
-             gl_cv_func_dup2_works=no;;
+             gl_cv_func_dup2_works="guessing no" ;;
            linux*) # On linux between 2008-07-27 and 2009-05-11, dup2 of a
                    # closed fd may yield -EBADF instead of -1 / errno=EBADF.
-             gl_cv_func_dup2_works=no;;
+             gl_cv_func_dup2_works="guessing no" ;;
            freebsd*) # on FreeBSD 6.1, dup2(1,1000000) gives EMFILE, not EBADF.
-             gl_cv_func_dup2_works=no;;
+             gl_cv_func_dup2_works="guessing no" ;;
            haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
-             gl_cv_func_dup2_works=no;;
-           *) gl_cv_func_dup2_works=yes;;
+             gl_cv_func_dup2_works="guessing no" ;;
+           *) gl_cv_func_dup2_works="guessing yes" ;;
          esac])
       ])
-    if test "$gl_cv_func_dup2_works" = no; then
-      gl_REPLACE_DUP2
-    fi
+    case "$gl_cv_func_dup2_works" in
+      *yes) ;;
+      *)
+        REPLACE_DUP2=1
+        ;;
+    esac
   fi
+  dnl Replace dup2() for supporting the gnulib-defined fchdir() function,
+  dnl to keep fchdir's bookkeeping up-to-date.
+  m4_ifdef([gl_FUNC_FCHDIR], [
+    gl_TEST_FCHDIR
+    if test $HAVE_FCHDIR = 0; then
+      if test $HAVE_DUP2 = 1; then
+        REPLACE_DUP2=1
+      fi
+    fi
+  ])
 ])
 
-AC_DEFUN([gl_REPLACE_DUP2],
-[
-  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
-  AC_CHECK_FUNCS_ONCE([dup2])
-  if test $ac_cv_func_dup2 = yes; then
-    REPLACE_DUP2=1
-  fi
-  AC_LIBOBJ([dup2])
-])
+# Prerequisites of lib/dup2.c.
+AC_DEFUN([gl_PREREQ_DUP2], [])