Merge from gnulib

This incorporates:
2017-07-16 explicit_bzero: new module
2017-07-15 getdtablesize: Add minimal support for OpenVMS.
* lib/getdtablesize.c, lib/string.in.h, m4/getdtablesize.m4:
* m4/string_h.m4:
Copy from Gnulib.
* lib/gnulib.mk.in: Regenerate.

2 files changed, 36 insertions, 20 deletions

diff --git a/m4/getdtablesize.m4 b/m4/getdtablesize.m4
index 1af2a2478fa..f1e4f5f699e 100644
--- a/m4/getdtablesize.m4
+++ b/m4/getdtablesize.m4
@@ -1,4 +1,4 @@
-# getdtablesize.m4 serial 6
+# getdtablesize.m4 serial 7
 dnl Copyright (C) 2008-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -12,29 +12,43 @@ AC_DEFUN([gl_FUNC_GETDTABLESIZE],
   AC_CHECK_DECLS_ONCE([getdtablesize])
   if test $ac_cv_func_getdtablesize = yes &&
      test $ac_cv_have_decl_getdtablesize = yes; then
-    # Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft limit
-    # up to an unchangeable hard limit; all other platforms correctly
-    # require setrlimit before getdtablesize() can report a larger value.
     AC_CACHE_CHECK([whether getdtablesize works],
       [gl_cv_func_getdtablesize_works],
-      [AC_RUN_IFELSE([
-        AC_LANG_PROGRAM([[#include <unistd.h>]],
-          [int size = getdtablesize();
-           if (dup2 (0, getdtablesize()) != -1)
-             return 1;
-           if (size != getdtablesize())
-             return 2;
-          ])],
-        [gl_cv_func_getdtablesize_works=yes],
-        [gl_cv_func_getdtablesize_works=no],
-        [case "$host_os" in
-          cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows
-            gl_cv_func_getdtablesize_works="guessing no" ;;
-          *) gl_cv_func_getdtablesize_works="guessing yes" ;;
-         esac])
+      [dnl There are two concepts: the "maximum possible file descriptor value + 1"
+       dnl and the "maximum number of open file descriptors in a process".
+       dnl Per SUSv2 and POSIX, getdtablesize() should return the first one.
+       dnl On most platforms, the first and the second concept are the same.
+       dnl On OpenVMS, however, they are different and getdtablesize() returns
+       dnl the second one; thus the test below fails. But we don't care
+       dnl because there's no good way to write a replacement getdtablesize().
+       case "$host_os" in
+         vms*) gl_cv_func_getdtablesize_works="no (limitation)" ;;
+         *)
+           dnl Cygwin 1.7.25 automatically increases the RLIMIT_NOFILE soft
+           dnl limit up to an unchangeable hard limit; all other platforms
+           dnl correctly require setrlimit before getdtablesize() can report
+           dnl a larger value.
+           AC_RUN_IFELSE([
+             AC_LANG_PROGRAM([[#include <unistd.h>]],
+               [int size = getdtablesize();
+                if (dup2 (0, getdtablesize()) != -1)
+                  return 1;
+                if (size != getdtablesize())
+                  return 2;
+               ])],
+             [gl_cv_func_getdtablesize_works=yes],
+             [gl_cv_func_getdtablesize_works=no],
+             [case "$host_os" in
+                cygwin*) # on cygwin 1.5.25, getdtablesize() automatically grows
+                  gl_cv_func_getdtablesize_works="guessing no" ;;
+                *) gl_cv_func_getdtablesize_works="guessing yes" ;;
+              esac
+             ])
+           ;;
+       esac
       ])
     case "$gl_cv_func_getdtablesize_works" in
-      *yes) ;;
+      *yes | "no (limitation)") ;;
       *) REPLACE_GETDTABLESIZE=1 ;;
     esac
   else
diff --git a/m4/string_h.m4 b/m4/string_h.m4
index 3d2ad2219a5..ac6311fba07 100644
--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@@ -43,6 +43,7 @@ AC_DEFUN([gl_STRING_MODULE_INDICATOR],
 
 AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
 [
+  GNULIB_EXPLICIT_BZERO=0; AC_SUBST([GNULIB_EXPLICIT_BZERO])
   GNULIB_FFSL=0;        AC_SUBST([GNULIB_FFSL])
   GNULIB_FFSLL=0;       AC_SUBST([GNULIB_FFSLL])
   GNULIB_MEMCHR=0;      AC_SUBST([GNULIB_MEMCHR])
@@ -82,6 +83,7 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   GNULIB_STRVERSCMP=0;  AC_SUBST([GNULIB_STRVERSCMP])
   HAVE_MBSLEN=0;        AC_SUBST([HAVE_MBSLEN])
   dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_EXPLICIT_BZERO=1;        AC_SUBST([HAVE_EXPLICIT_BZERO])
   HAVE_FFSL=1;                  AC_SUBST([HAVE_FFSL])
   HAVE_FFSLL=1;                 AC_SUBST([HAVE_FFSLL])
   HAVE_MEMCHR=1;                AC_SUBST([HAVE_MEMCHR])