Import upstream version 1.27

[debian/tar] / m4 / dup2.m4

diff --git a/m4/dup2.m4 b/m4/dup2.m4
index 054982359e8797502185fdd66064a47c7d3eedfd..269cfdc112380f35982e67535be4b179a1d55e1f 100644 (file)
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,5 +1,5 @@
-#serial 5
-dnl Copyright (C) 2002, 2005, 2007 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.
@@ -7,9 +7,78 @@ dnl with or without modifications, as long as this notice is preserved.
 AC_DEFUN([gl_FUNC_DUP2],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
-  AC_CHECK_FUNCS_ONCE([dup2])
-  if test $ac_cv_func_dup2 = no; then
-    HAVE_DUP2=0
-    AC_LIBOBJ([dup2])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  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 $HAVE_DUP2 = 1; then
+    AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
+      [AC_RUN_IFELSE([
+         AC_LANG_PROGRAM([[#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>]],
+           [int result = 0;
+#ifdef FD_CLOEXEC
+            if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
+              result |= 1;
+#endif
+            if (dup2 (1, 1) == 0)
+              result |= 2;
+#ifdef FD_CLOEXEC
+            if (fcntl (1, F_GETFD) != FD_CLOEXEC)
+              result |= 4;
+#endif
+            close (0);
+            if (dup2 (0, 0) != -1)
+              result |= 8;
+            /* Many gnulib modules require POSIX conformance of EBADF.  */
+            if (dup2 (2, 1000000) == -1 && errno != EBADF)
+              result |= 16;
+            /* Flush out a cygwin core dump.  */
+            if (dup2 (2, -1) != -1 || errno != EBADF)
+              result |= 32;
+            return result;
+           ])
+        ],
+        [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
+        [case "$host_os" in
+           mingw*) # on this platform, dup2 always returns 0 for success
+             gl_cv_func_dup2_works="guessing no" ;;
+           cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
+             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="guessing no" ;;
+           freebsd*) # on FreeBSD 6.1, dup2(1,1000000) gives EMFILE, not EBADF.
+             gl_cv_func_dup2_works="guessing no" ;;
+           haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
+             gl_cv_func_dup2_works="guessing no" ;;
+           *) gl_cv_func_dup2_works="guessing yes" ;;
+         esac])
+      ])
+    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
+  ])
 ])
+
+# Prerequisites of lib/dup2.c.
+AC_DEFUN([gl_PREREQ_DUP2], [])