X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/fd60bf6c902b47daadda6ebf442045dbe1328941..1048151cc4bec79f7310f4f2ede309889822a6bb:/m4/dup2.m4

diff --git a/m4/dup2.m4 b/m4/dup2.m4
index 6498fc2024..5b68312b1e 100644
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,5 +1,5 @@
-#serial 20
-dnl Copyright (C) 2002, 2005, 2007, 2009-2014 Free Software Foundation, Inc.
+#serial 25
+dnl Copyright (C) 2002, 2005, 2007, 2009-2016 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.
@@ -8,7 +8,6 @@ AC_DEFUN([gl_FUNC_DUP2],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
-  AC_CHECK_FUNCS_ONCE([getdtablesize])
   m4_ifdef([gl_FUNC_DUP2_OBSOLETE], [
     AC_CHECK_FUNCS_ONCE([dup2])
     if test $ac_cv_func_dup2 = no; then
@@ -20,38 +19,60 @@ AC_DEFUN([gl_FUNC_DUP2],
   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 HAVE_GETDTABLESIZE
-            int bad_fd = getdtablesize ();
-#else
-            int bad_fd = 1000000;
-#endif
-#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, bad_fd) == -1 && errno != EBADF)
-              result |= 16;
-            /* Flush out some cygwin core dumps.  */
-            if (dup2 (2, -1) != -1 || errno != EBADF)
-              result |= 32;
-            dup2 (2, 255);
-            dup2 (2, 256);
-            return result;
-           ])
+         AC_LANG_PROGRAM(
+           [[#include <errno.h>
+             #include <fcntl.h>
+             #include <limits.h>
+             #include <sys/resource.h>
+             #include <unistd.h>
+             #ifndef RLIM_SAVED_CUR
+             # define RLIM_SAVED_CUR RLIM_INFINITY
+             #endif
+             #ifndef RLIM_SAVED_MAX
+             # define RLIM_SAVED_MAX RLIM_INFINITY
+             #endif
+           ]],
+           [[int result = 0;
+             int bad_fd = INT_MAX;
+             struct rlimit rlim;
+             if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
+                 && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
+                 && rlim.rlim_cur != RLIM_INFINITY
+                 && rlim.rlim_cur != RLIM_SAVED_MAX
+                 && rlim.rlim_cur != RLIM_SAVED_CUR)
+               bad_fd = rlim.rlim_cur;
+             #ifdef FD_CLOEXEC
+               if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
+                 result |= 1;
+             #endif
+             if (dup2 (1, 1) != 1)
+               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, bad_fd) == -1 && errno != EBADF)
+               result |= 16;
+             /* Flush out some cygwin core dumps.  */
+             if (dup2 (2, -1) != -1 || errno != EBADF)
+               result |= 32;
+             dup2 (2, 255);
+             dup2 (2, 256);
+             /* On OS/2 kLIBC, dup2() does not work on a directory fd.  */
+             {
+               int fd = open (".", O_RDONLY);
+               if (fd == -1)
+                 result |= 64;
+               else if (dup2 (fd, fd + 1) == -1)
+                 result |= 128;
+
+               close (fd);
+             }
+             return result;]])
         ],
         [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
         [case "$host_os" in
@@ -59,15 +80,16 @@ AC_DEFUN([gl_FUNC_DUP2],
              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" ;;
            aix* | freebsd*)
                    # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) 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" ;;
+           *-android*) # implemented using dup3(), which fails if oldfd == newfd
+             gl_cv_func_dup2_works="guessing no" ;;
+           os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
+             gl_cv_func_dup2_works="guessing no" ;;
            *) gl_cv_func_dup2_works="guessing yes" ;;
          esac])
       ])