X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fdup2.m4;h=cd9d254b440740db278a1cf3cc903623d29b81ba;hb=effe7821374f8b7e22e9de3df9cc4e5f285712bd;hp=2abc74cdc551fb30cebcf5ec05e8e06c9f9672da;hpb=ddd625ddd088a87d5598256d09b2036c63063386;p=gnulib.git

diff --git a/m4/dup2.m4 b/m4/dup2.m4
index 2abc74cdc..cd9d254b4 100644
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,5 +1,5 @@
-#serial 6
-dnl Copyright (C) 2002, 2005, 2007, 2009 Free Software Foundation, Inc.
+#serial 16
+dnl Copyright (C) 2002, 2005, 2007, 2009-2011 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.
@@ -8,28 +8,69 @@ AC_DEFUN([gl_FUNC_DUP2],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
-  AC_CHECK_FUNCS_ONCE([dup2])
-  if test $ac_cv_func_dup2 = no; then
-    HAVE_DUP2=0
-    AC_LIBOBJ([dup2])
-  else
+  m4_ifdef([gl_FUNC_DUP2_OBSOLETE], [
+    AC_CHECK_FUNCS_ONCE([dup2])
+    if test $ac_cv_func_dup2 = no; then
+      HAVE_DUP2=0
+    fi
+  ], [
+    AC_DEFINE([HAVE_DUP2], [1], [Define to 1 if you have the 'dup2' function.])
+  ])
+  if test $HAVE_DUP2 = 1; then
     AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
-      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
-#include <unistd.h>
-]], [return 1 - dup2 (1, 1);])],
-	[gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
-	[case "$host_os" in
-	   mingw*) # on this platform, dup2 always returns 0 for success
-	     gl_cv_func_dup2_works=no;;
-	   cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
-	     gl_cv_func_dup2_works=no;;
-	   *) gl_cv_func_dup2_works=yes;;
-	 esac])])
+      [AC_RUN_IFELSE([
+         AC_LANG_PROGRAM([[#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>]],
+           [int result = 0;
+#ifdef FD_CLOEXEC
+            if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
+              result |= 1;
+#endif
+            if (dup2 (1, 1) == 0)
+              result |= 2;
+#ifdef FD_CLOEXEC
+            if (fcntl (1, F_GETFD) != FD_CLOEXEC)
+              result |= 4;
+#endif
+            close (0);
+            if (dup2 (0, 0) != -1)
+              result |= 8;
+            /* Many gnulib modules require POSIX conformance of EBADF.  */
+            if (dup2 (2, 1000000) == -1 && errno != EBADF)
+              result |= 16;
+            return result;
+           ])
+        ],
+        [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
+        [case "$host_os" in
+           mingw*) # on this platform, dup2 always returns 0 for success
+             gl_cv_func_dup2_works=no;;
+           cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
+             gl_cv_func_dup2_works=no;;
+           linux*) # On linux between 2008-07-27 and 2009-05-11, dup2 of a
+                   # closed fd may yield -EBADF instead of -1 / errno=EBADF.
+             gl_cv_func_dup2_works=no;;
+           freebsd*) # on FreeBSD 6.1, dup2(1,1000000) gives EMFILE, not EBADF.
+             gl_cv_func_dup2_works=no;;
+           haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
+             gl_cv_func_dup2_works=no;;
+           *) gl_cv_func_dup2_works=yes;;
+         esac])
+      ])
     if test "$gl_cv_func_dup2_works" = no; then
       REPLACE_DUP2=1
-      AC_LIBOBJ([dup2])
     fi
   fi
-  AC_DEFINE_UNQUOTED([REPLACE_DUP2], [$REPLACE_DUP2],
-    [Define to 1 if dup2 returns 0 instead of the target fd.])
+  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
+      REPLACE_DUP2=1
+    fi
+  ])
 ])
+
+# Prerequisites of lib/dup2.c.
+AC_DEFUN([gl_PREREQ_DUP2], [])