Merge from Gnulib; use ‘open’ for O_CLOEXEC

This incorporates:
2017-08-15 renameat: ensure declaration in <stdio.h> on NetBSD
2017-08-15 extensions: enable NetBSD specific extensions
2017-08-14 open: support O_CLOEXEC
2017-08-13 reallocarray: new module
* admin/merge-gnulib (AVOIDED_MODULES): Remove ‘open’, since
it now supports O_CLOEXEC and this simplifies Emacs.
* build-aux/config.guess, lib/fcntl.in.h, lib/stdio.in.h:
* lib/stdlib.in.h, m4/extensions.m4, m4/stdlib_h.m4:
Copy from Gnulib.
* lib/cloexec.c, lib/cloexec.h, lib/open.c:
* m4/mode_t.m4, m4/open-cloexec.m4, m4/open.m4:
New files, copied from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib-src/etags.c (O_CLOEXEC) [WINDOWSNT]:
Remove, as Gnulib does this for us.
* src/filelock.c (create_lock_file):
* src/sysdep.c (emacs_open, emacs_pipe):
Don’t worry about O_CLOEXEC == 0, as Gnulib no longer sets it to 0.

18 files changed, 578 insertions, 22 deletions

diff --git a/admin/merge-gnulib b/admin/merge-gnulib
index 7eca64305de..e7b304a264d 100755
--- a/admin/merge-gnulib
+++ b/admin/merge-gnulib
@@ -48,7 +48,7 @@ GNULIB_MODULES='
 AVOIDED_MODULES='
   close dup fchdir fstat
   malloc-posix msvc-inval msvc-nothrow
-  open openat-die opendir raise
+  openat-die opendir raise
   save-cwd select setenv sigprocmask stat stdarg stdbool
   threadlib tzset unsetenv utime utime-h
 '
diff --git a/build-aux/config.guess b/build-aux/config.guess
index 07785f54515..a7448442748 100755
--- a/build-aux/config.guess
+++ b/build-aux/config.guess
@@ -2,7 +2,7 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2017 Free Software Foundation, Inc.
 
-timestamp='2017-07-19'
+timestamp='2017-08-08'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -259,6 +259,9 @@ case "${UNAME_MACHINE}:${UNAME_SYSTEM}:${UNAME_RELEASE}:${UNAME_VERSION}" in
     *:Sortix:*:*)
         echo ${UNAME_MACHINE}-unknown-sortix
         exit ;;
+    *:Redox:*:*)
+        echo ${UNAME_MACHINE}-unknown-redox
+        exit ;;
     alpha:OSF1:*:*)
         case $UNAME_RELEASE in
         *4.0)
diff --git a/lib-src/etags.c b/lib-src/etags.c
index 7b1a7fc1851..bec61a8a230 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -111,7 +111,6 @@ char pot_etags_version[] = "@(#) pot revision number is 17.38.1.4";
 # undef HAVE_NTGUI
 # undef  DOS_NT
 # define DOS_NT
-# define O_CLOEXEC O_NOINHERIT
 #endif /* WINDOWSNT */
 
 #include <limits.h>
diff --git a/lib/cloexec.c b/lib/cloexec.c
new file mode 100644
index 00000000000..e34aef87976
--- /dev/null
+++ b/lib/cloexec.c
@@ -0,0 +1,83 @@
+/* cloexec.c - set or clear the close-on-exec descriptor flag
+
+   Copyright (C) 1991, 2004-2006, 2009-2017 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+   The code is taken from glibc/manual/llio.texi  */
+
+#include <config.h>
+
+#include "cloexec.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true,
+   or clear the flag if VALUE is false.
+   Return 0 on success, or -1 on error with 'errno' set.
+
+   Note that on MingW, this function does NOT protect DESC from being
+   inherited into spawned children.  Instead, either use dup_cloexec
+   followed by closing the original DESC, or use interfaces such as
+   open or pipe2 that accept flags like O_CLOEXEC to create DESC
+   non-inheritable in the first place.  */
+
+int
+set_cloexec_flag (int desc, bool value)
+{
+#ifdef F_SETFD
+
+  int flags = fcntl (desc, F_GETFD, 0);
+
+  if (0 <= flags)
+    {
+      int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
+
+      if (flags == newflags
+          || fcntl (desc, F_SETFD, newflags) != -1)
+        return 0;
+    }
+
+  return -1;
+
+#else /* !F_SETFD */
+
+  /* Use dup2 to reject invalid file descriptors; the cloexec flag
+     will be unaffected.  */
+  if (desc < 0)
+    {
+      errno = EBADF;
+      return -1;
+    }
+  if (dup2 (desc, desc) < 0)
+    /* errno is EBADF here.  */
+    return -1;
+
+  /* There is nothing we can do on this kind of platform.  Punt.  */
+  return 0;
+#endif /* !F_SETFD */
+}
+
+
+/* Duplicates a file handle FD, while marking the copy to be closed
+   prior to exec or spawn.  Returns -1 and sets errno if FD could not
+   be duplicated.  */
+
+int
+dup_cloexec (int fd)
+{
+  return fcntl (fd, F_DUPFD_CLOEXEC, 0);
+}
diff --git a/lib/cloexec.h b/lib/cloexec.h
new file mode 100644
index 00000000000..cdaf422226d
--- /dev/null
+++ b/lib/cloexec.h
@@ -0,0 +1,38 @@
+/* cloexec.c - set or clear the close-on-exec descriptor flag
+
+   Copyright (C) 2004, 2009-2017 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+#include <stdbool.h>
+
+/* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true,
+   or clear the flag if VALUE is false.
+   Return 0 on success, or -1 on error with 'errno' set.
+
+   Note that on MingW, this function does NOT protect DESC from being
+   inherited into spawned children.  Instead, either use dup_cloexec
+   followed by closing the original DESC, or use interfaces such as
+   open or pipe2 that accept flags like O_CLOEXEC to create DESC
+   non-inheritable in the first place.  */
+
+int set_cloexec_flag (int desc, bool value);
+
+/* Duplicates a file handle FD, while marking the copy to be closed
+   prior to exec or spawn.  Returns -1 and sets errno if FD could not
+   be duplicated.  */
+
+int dup_cloexec (int fd);
diff --git a/lib/fcntl.in.h b/lib/fcntl.in.h
index 4a1d40af6df..076d1ac34a7 100644
--- a/lib/fcntl.in.h
+++ b/lib/fcntl.in.h
@@ -213,7 +213,10 @@ _GL_WARN_ON_USE (openat, "openat is not portable - "
 #endif
 
 #ifndef O_CLOEXEC
-# define O_CLOEXEC 0
+# define O_CLOEXEC 0x40000000 /* Try to not collide with system O_* flags.  */
+# define GNULIB_defined_O_CLOEXEC 1
+#else
+# define GNULIB_defined_O_CLOEXEC 0
 #endif
 
 #ifndef O_DIRECT
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index 30986b4ed7f..b6eb0f69539 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -21,7 +21,7 @@
 # the same distribution terms as the rest of that program.
 #
 # Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=tzset --avoid=unsetenv --avoid=utime --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 d-type diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr minmax mkostemp mktime nstrftime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strtoimax symlink sys_stat sys_time tempname time time_r time_rz timegm timer-time timespec-add timespec-sub unlocked-io update-copyright utimens vla warnings
+# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=tzset --avoid=unsetenv --avoid=utime --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 d-type diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr minmax mkostemp mktime nstrftime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strtoimax symlink sys_stat sys_time tempname time time_r time_rz timegm timer-time timespec-add timespec-sub unlocked-io update-copyright utimens vla warnings
 
 
 MOSTLYCLEANFILES += core *.stackdump
@@ -255,6 +255,7 @@ GNULIB_READ = @GNULIB_READ@
 GNULIB_READDIR = @GNULIB_READDIR@
 GNULIB_READLINK = @GNULIB_READLINK@
 GNULIB_READLINKAT = @GNULIB_READLINKAT@
+GNULIB_REALLOCARRAY = @GNULIB_REALLOCARRAY@
 GNULIB_REALLOC_POSIX = @GNULIB_REALLOC_POSIX@
 GNULIB_REALPATH = @GNULIB_REALPATH@
 GNULIB_REMOVE = @GNULIB_REMOVE@
@@ -465,6 +466,7 @@ HAVE_RAWMEMCHR = @HAVE_RAWMEMCHR@
 HAVE_READDIR = @HAVE_READDIR@
 HAVE_READLINK = @HAVE_READLINK@
 HAVE_READLINKAT = @HAVE_READLINKAT@
+HAVE_REALLOCARRAY = @HAVE_REALLOCARRAY@
 HAVE_REALPATH = @HAVE_REALPATH@
 HAVE_RENAMEAT = @HAVE_RENAMEAT@
 HAVE_REWINDDIR = @HAVE_REWINDDIR@
@@ -898,11 +900,13 @@ gl_GNULIB_ENABLED_6099e9737f757db36c47fa9d9f02e88c = @gl_GNULIB_ENABLED_6099e973
 gl_GNULIB_ENABLED_682e609604ccaac6be382e4ee3a4eaec = @gl_GNULIB_ENABLED_682e609604ccaac6be382e4ee3a4eaec@
 gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1 = @gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1@
 gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36 = @gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36@
+gl_GNULIB_ENABLED_cloexec = @gl_GNULIB_ENABLED_cloexec@
 gl_GNULIB_ENABLED_dirfd = @gl_GNULIB_ENABLED_dirfd@
 gl_GNULIB_ENABLED_dosname = @gl_GNULIB_ENABLED_dosname@
 gl_GNULIB_ENABLED_euidaccess = @gl_GNULIB_ENABLED_euidaccess@
 gl_GNULIB_ENABLED_getdtablesize = @gl_GNULIB_ENABLED_getdtablesize@
 gl_GNULIB_ENABLED_getgroups = @gl_GNULIB_ENABLED_getgroups@
+gl_GNULIB_ENABLED_open = @gl_GNULIB_ENABLED_open@
 gl_GNULIB_ENABLED_strtoll = @gl_GNULIB_ENABLED_strtoll@
 gl_LIBOBJS = @gl_LIBOBJS@
 gl_LTLIBOBJS = @gl_LTLIBOBJS@
@@ -1085,6 +1089,18 @@ EXTRA_DIST += careadlinkat.h
 endif
 ## end   gnulib module careadlinkat
 
+## begin gnulib module cloexec
+ifeq (,$(OMIT_GNULIB_MODULE_cloexec))
+
+ifneq (,$(gl_GNULIB_ENABLED_cloexec))
+libgnu_a_SOURCES += cloexec.c
+
+endif
+EXTRA_DIST += cloexec.h
+
+endif
+## end   gnulib module cloexec
+
 ## begin gnulib module close-stream
 ifeq (,$(OMIT_GNULIB_MODULE_close-stream))
 
@@ -1817,6 +1833,19 @@ EXTRA_DIST += strftime.h
 endif
 ## end   gnulib module nstrftime
 
+## begin gnulib module open
+ifeq (,$(OMIT_GNULIB_MODULE_open))
+
+ifneq (,$(gl_GNULIB_ENABLED_open))
+
+endif
+EXTRA_DIST += open.c
+
+EXTRA_libgnu_a_SOURCES += open.c
+
+endif
+## end   gnulib module open
+
 ## begin gnulib module openat-h
 ifeq (,$(OMIT_GNULIB_MODULE_openat-h))
 
@@ -2311,6 +2340,7 @@ stdlib.h: stdlib.in.h $(top_builddir)/config.status $(CXXDEFS_H) \
               -e 's/@''GNULIB_RANDOM''@/$(GNULIB_RANDOM)/g' \
               -e 's/@''GNULIB_RANDOM_R''@/$(GNULIB_RANDOM_R)/g' \
               -e 's/@''GNULIB_REALLOC_POSIX''@/$(GNULIB_REALLOC_POSIX)/g' \
+              -e 's/@''GNULIB_REALLOCARRAY''@/$(GNULIB_REALLOCARRAY)/g' \
               -e 's/@''GNULIB_REALPATH''@/$(GNULIB_REALPATH)/g' \
               -e 's/@''GNULIB_RPMATCH''@/$(GNULIB_RPMATCH)/g' \
               -e 's/@''GNULIB_SECURE_GETENV''@/$(GNULIB_SECURE_GETENV)/g' \
@@ -2341,6 +2371,7 @@ stdlib.h: stdlib.in.h $(top_builddir)/config.status $(CXXDEFS_H) \
               -e 's|@''HAVE_RANDOM''@|$(HAVE_RANDOM)|g' \
               -e 's|@''HAVE_RANDOM_H''@|$(HAVE_RANDOM_H)|g' \
               -e 's|@''HAVE_RANDOM_R''@|$(HAVE_RANDOM_R)|g' \
+              -e 's|@''HAVE_REALLOCARRAY''@|$(HAVE_REALLOCARRAY)|g' \
               -e 's|@''HAVE_REALPATH''@|$(HAVE_REALPATH)|g' \
               -e 's|@''HAVE_RPMATCH''@|$(HAVE_RPMATCH)|g' \
               -e 's|@''HAVE_SECURE_GETENV''@|$(HAVE_SECURE_GETENV)|g' \
diff --git a/lib/open.c b/lib/open.c
new file mode 100644
index 00000000000..c62f02b1452
--- /dev/null
+++ b/lib/open.c
@@ -0,0 +1,208 @@
+/* Open a descriptor to a file.
+   Copyright (C) 2007-2017 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
+
+/* If the user's config.h happens to include <fcntl.h>, let it include only
+   the system's <fcntl.h> here, so that orig_open doesn't recurse to
+   rpl_open.  */
+#define __need_system_fcntl_h
+#include <config.h>
+
+/* Get the original definition of open.  It might be defined as a macro.  */
+#include <fcntl.h>
+#include <sys/types.h>
+#undef __need_system_fcntl_h
+
+static int
+orig_open (const char *filename, int flags, mode_t mode)
+{
+  return open (filename, flags, mode);
+}
+
+/* Specification.  */
+/* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
+   this include because of the preliminary #include <fcntl.h> above.  */
+#include "fcntl.h"
+
+#include "cloexec.h"
+
+#include <errno.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#ifndef REPLACE_OPEN_DIRECTORY
+# define REPLACE_OPEN_DIRECTORY 0
+#endif
+
+int
+open (const char *filename, int flags, ...)
+{
+  /* 0 = unknown, 1 = yes, -1 = no.  */
+#if GNULIB_defined_O_CLOEXEC
+  int have_cloexec = -1;
+#else
+  static int have_cloexec;
+#endif
+
+  mode_t mode;
+  int fd;
+
+  mode = 0;
+  if (flags & O_CREAT)
+    {
+      va_list arg;
+      va_start (arg, flags);
+
+      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+         creates crashing code when 'mode_t' is smaller than 'int'.  */
+      mode = va_arg (arg, PROMOTED_MODE_T);
+
+      va_end (arg);
+    }
+
+#if GNULIB_defined_O_NONBLOCK
+  /* The only known platform that lacks O_NONBLOCK is mingw, but it
+     also lacks named pipes and Unix sockets, which are the only two
+     file types that require non-blocking handling in open().
+     Therefore, it is safe to ignore O_NONBLOCK here.  It is handy
+     that mingw also lacks openat(), so that is also covered here.  */
+  flags &= ~O_NONBLOCK;
+#endif
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+  if (strcmp (filename, "/dev/null") == 0)
+    filename = "NUL";
+#endif
+
+#if OPEN_TRAILING_SLASH_BUG
+  /* If the filename ends in a slash and one of O_CREAT, O_WRONLY, O_RDWR
+     is specified, then fail.
+     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+     says that
+       "A pathname that contains at least one non-slash character and that
+        ends with one or more trailing slashes shall be resolved as if a
+        single dot character ( '.' ) were appended to the pathname."
+     and
+       "The special filename dot shall refer to the directory specified by
+        its predecessor."
+     If the named file already exists as a directory, then
+       - if O_CREAT is specified, open() must fail because of the semantics
+         of O_CREAT,
+       - if O_WRONLY or O_RDWR is specified, open() must fail because POSIX
+         <http://www.opengroup.org/susv3/functions/open.html> says that it
+         fails with errno = EISDIR in this case.
+     If the named file does not exist or does not name a directory, then
+       - if O_CREAT is specified, open() must fail since open() cannot create
+         directories,
+       - if O_WRONLY or O_RDWR is specified, open() must fail because the
+         file does not contain a '.' directory.  */
+  if (flags & (O_CREAT | O_WRONLY | O_RDWR))
+    {
+      size_t len = strlen (filename);
+      if (len > 0 && filename[len - 1] == '/')
+        {
+          errno = EISDIR;
+          return -1;
+        }
+    }
+#endif
+
+  fd = orig_open (filename,
+                  flags & ~(have_cloexec <= 0 ? O_CLOEXEC : 0), mode);
+
+  if (flags & O_CLOEXEC)
+    {
+      if (! have_cloexec)
+        {
+          if (0 <= fd)
+            have_cloexec = 1;
+          else if (errno == EINVAL)
+            {
+              fd = orig_open (filename, flags & ~O_CLOEXEC, mode);
+              have_cloexec = -1;
+            }
+        }
+      if (have_cloexec < 0 && 0 <= fd)
+        set_cloexec_flag (fd, true);
+    }
+
+
+#if REPLACE_FCHDIR
+  /* Implementing fchdir and fdopendir requires the ability to open a
+     directory file descriptor.  If open doesn't support that (as on
+     mingw), we use a dummy file that behaves the same as directories
+     on Linux (ie. always reports EOF on attempts to read()), and
+     override fstat() in fchdir.c to hide the fact that we have a
+     dummy.  */
+  if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
+      && ((flags & O_ACCMODE) == O_RDONLY
+          || (O_SEARCH != O_RDONLY && (flags & O_ACCMODE) == O_SEARCH)))
+    {
+      struct stat statbuf;
+      if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
+        {
+          /* Maximum recursion depth of 1.  */
+          fd = open ("/dev/null", flags, mode);
+          if (0 <= fd)
+            fd = _gl_register_fd (fd, filename);
+        }
+      else
+        errno = EACCES;
+    }
+#endif
+
+#if OPEN_TRAILING_SLASH_BUG
+  /* If the filename ends in a slash and fd does not refer to a directory,
+     then fail.
+     Rationale: POSIX <http://www.opengroup.org/susv3/basedefs/xbd_chap04.html>
+     says that
+       "A pathname that contains at least one non-slash character and that
+        ends with one or more trailing slashes shall be resolved as if a
+        single dot character ( '.' ) were appended to the pathname."
+     and
+       "The special filename dot shall refer to the directory specified by
+        its predecessor."
+     If the named file without the slash is not a directory, open() must fail
+     with ENOTDIR.  */
+  if (fd >= 0)
+    {
+      /* We know len is positive, since open did not fail with ENOENT.  */
+      size_t len = strlen (filename);
+      if (filename[len - 1] == '/')
+        {
+          struct stat statbuf;
+
+          if (fstat (fd, &statbuf) >= 0 && !S_ISDIR (statbuf.st_mode))
+            {
+              close (fd);
+              errno = ENOTDIR;
+              return -1;
+            }
+        }
+    }
+#endif
+
+#if REPLACE_FCHDIR
+  if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
+    fd = _gl_register_fd (fd, filename);
+#endif
+
+  return fd;
+}
diff --git a/lib/stdio.in.h b/lib/stdio.in.h
index d706377f984..b714c54a544 100644
--- a/lib/stdio.in.h
+++ b/lib/stdio.in.h
@@ -111,9 +111,9 @@
 #define _GL_ATTRIBUTE_FORMAT_SCANF_SYSTEM(formatstring_parameter, first_argument) \
   _GL_ATTRIBUTE_FORMAT ((__scanf__, formatstring_parameter, first_argument))
 
-/* Solaris 10 declares renameat in <unistd.h>, not in <stdio.h>.  */
+/* Solaris 10 and NetBSD 7.0 declare renameat in <unistd.h>, not in <stdio.h>.  */
 /* But in any case avoid namespace pollution on glibc systems.  */
-#if (@GNULIB_RENAMEAT@ || defined GNULIB_POSIXCHECK) && defined __sun \
+#if (@GNULIB_RENAMEAT@ || defined GNULIB_POSIXCHECK) && (defined __sun || defined __NetBSD__) \
     && ! defined __GLIBC__
 # include <unistd.h>
 #endif
diff --git a/lib/stdlib.in.h b/lib/stdlib.in.h
index b5cf9d36958..c6e68fddc48 100644
--- a/lib/stdlib.in.h
+++ b/lib/stdlib.in.h
@@ -765,6 +765,23 @@ _GL_WARN_ON_USE (realloc, "realloc is not POSIX compliant everywhere - "
                  "use gnulib module realloc-posix for portability");
 #endif
 
+
+#if @GNULIB_REALLOCARRAY@
+# if ! @HAVE_REALLOCARRAY@
+_GL_FUNCDECL_SYS (reallocarray, void *,
+                  (void *ptr, size_t nmemb, size_t size));
+# endif
+_GL_CXXALIAS_SYS (reallocarray, void *,
+                  (void *ptr, size_t nmemb, size_t size));
+_GL_CXXALIASWARN (reallocarray);
+#elif defined GNULIB_POSIXCHECK
+# undef reallocarray
+# if HAVE_RAW_DECL_REALLOCARRAY
+_GL_WARN_ON_USE (reallocarray, "reallocarray is not portable - "
+                 "use gnulib module reallocarray for portability");
+# endif
+#endif
+
 #if @GNULIB_REALPATH@
 # if @REPLACE_REALPATH@
 #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
diff --git a/m4/extensions.m4 b/m4/extensions.m4
index 0c16bb832f8..f8543386795 100644
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,4 +1,4 @@
-# serial 16  -*- Autoconf -*-
+# serial 17  -*- Autoconf -*-
 # Enable extensions on systems that normally disable them.
 
 # Copyright (C) 2003, 2006-2017 Free Software Foundation, Inc.
@@ -68,6 +68,10 @@ dnl configure.ac when using autoheader 2.62.
 #ifndef _GNU_SOURCE
 # undef _GNU_SOURCE
 #endif
+/* Enable NetBSD extensions on NetBSD.  */
+#ifndef _NETBSD_SOURCE
+# undef _NETBSD_SOURCE
+#endif
 /* Enable OpenBSD extensions on NetBSD.  */
 #ifndef _OPENBSD_SOURCE
 # undef _OPENBSD_SOURCE
@@ -132,6 +136,7 @@ dnl configure.ac when using autoheader 2.62.
   AC_DEFINE([_ALL_SOURCE])
   AC_DEFINE([_DARWIN_C_SOURCE])
   AC_DEFINE([_GNU_SOURCE])
+  AC_DEFINE([_NETBSD_SOURCE])
   AC_DEFINE([_OPENBSD_SOURCE])
   AC_DEFINE([_POSIX_PTHREAD_SEMANTICS])
   AC_DEFINE([__STDC_WANT_IEC_60559_ATTRIBS_EXT__])
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index d1089860e19..13504a8ca20 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -53,6 +53,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module c-strcase:
   # Code from module careadlinkat:
   # Code from module clock-time:
+  # Code from module cloexec:
   # Code from module close-stream:
   # Code from module count-leading-zeros:
   # Code from module count-one-bits:
@@ -115,6 +116,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module multiarch:
   # Code from module nocrash:
   # Code from module nstrftime:
+  # Code from module open:
   # Code from module openat-h:
   # Code from module pipe2:
   # Code from module pselect:
@@ -413,6 +415,7 @@ AC_DEFUN([gl_INIT],
   gl_UTIMENS
   AC_C_VARARRAYS
   gl_gnulib_enabled_260941c0e5dc67ec9e87d1fb321c300b=false
+  gl_gnulib_enabled_cloexec=false
   gl_gnulib_enabled_dirfd=false
   gl_gnulib_enabled_dosname=false
   gl_gnulib_enabled_euidaccess=false
@@ -422,6 +425,7 @@ AC_DEFUN([gl_INIT],
   gl_gnulib_enabled_a9786850e999ae65a836a6041e8e5ed1=false
   gl_gnulib_enabled_2049e887c7e5308faad27b3f894bb8c9=false
   gl_gnulib_enabled_5264294aa0a5557541b53c8c741f7f31=false
+  gl_gnulib_enabled_open=false
   gl_gnulib_enabled_03e0aaad4cb89ca757653bd367a6ccb7=false
   gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c=false
   gl_gnulib_enabled_strtoll=false
@@ -431,6 +435,14 @@ AC_DEFUN([gl_INIT],
     if ! $gl_gnulib_enabled_260941c0e5dc67ec9e87d1fb321c300b; then
       AC_LIBOBJ([openat-proc])
       gl_gnulib_enabled_260941c0e5dc67ec9e87d1fb321c300b=true
+      func_gl_gnulib_m4code_open
+    fi
+  }
+  func_gl_gnulib_m4code_cloexec ()
+  {
+    if ! $gl_gnulib_enabled_cloexec; then
+      gl_MODULE_INDICATOR_FOR_TESTS([cloexec])
+      gl_gnulib_enabled_cloexec=true
     fi
   }
   func_gl_gnulib_m4code_dirfd ()
@@ -536,6 +548,21 @@ AC_DEFUN([gl_INIT],
       gl_gnulib_enabled_5264294aa0a5557541b53c8c741f7f31=true
     fi
   }
+  func_gl_gnulib_m4code_open ()
+  {
+    if ! $gl_gnulib_enabled_open; then
+      gl_FUNC_OPEN
+      if test $REPLACE_OPEN = 1; then
+        AC_LIBOBJ([open])
+        gl_PREREQ_OPEN
+      fi
+      gl_FCNTL_MODULE_INDICATOR([open])
+      gl_gnulib_enabled_open=true
+      if test $REPLACE_OPEN = 1; then
+        func_gl_gnulib_m4code_cloexec
+      fi
+    fi
+  }
   func_gl_gnulib_m4code_03e0aaad4cb89ca757653bd367a6ccb7 ()
   {
     if ! $gl_gnulib_enabled_03e0aaad4cb89ca757653bd367a6ccb7; then
@@ -622,6 +649,7 @@ AC_DEFUN([gl_INIT],
   fi
   m4_pattern_allow([^gl_GNULIB_ENABLED_])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_260941c0e5dc67ec9e87d1fb321c300b], [$gl_gnulib_enabled_260941c0e5dc67ec9e87d1fb321c300b])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_cloexec], [$gl_gnulib_enabled_cloexec])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_dirfd], [$gl_gnulib_enabled_dirfd])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_dosname], [$gl_gnulib_enabled_dosname])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_euidaccess], [$gl_gnulib_enabled_euidaccess])
@@ -631,6 +659,7 @@ AC_DEFUN([gl_INIT],
   AM_CONDITIONAL([gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1], [$gl_gnulib_enabled_a9786850e999ae65a836a6041e8e5ed1])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_2049e887c7e5308faad27b3f894bb8c9], [$gl_gnulib_enabled_2049e887c7e5308faad27b3f894bb8c9])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_5264294aa0a5557541b53c8c741f7f31], [$gl_gnulib_enabled_5264294aa0a5557541b53c8c741f7f31])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_open], [$gl_gnulib_enabled_open])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_03e0aaad4cb89ca757653bd367a6ccb7], [$gl_gnulib_enabled_03e0aaad4cb89ca757653bd367a6ccb7])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_6099e9737f757db36c47fa9d9f02e88c], [$gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_strtoll], [$gl_gnulib_enabled_strtoll])
@@ -800,6 +829,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/c-strncasecmp.c
   lib/careadlinkat.c
   lib/careadlinkat.h
+  lib/cloexec.c
+  lib/cloexec.h
   lib/close-stream.c
   lib/close-stream.h
   lib/count-leading-zeros.c
@@ -869,6 +900,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/mktime-internal.h
   lib/mktime.c
   lib/nstrftime.c
+  lib/open.c
   lib/openat-priv.h
   lib/openat-proc.c
   lib/openat.h
@@ -987,10 +1019,13 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/minmax.m4
   m4/mkostemp.m4
   m4/mktime.m4
+  m4/mode_t.m4
   m4/multiarch.m4
   m4/nocrash.m4
   m4/nstrftime.m4
   m4/off_t.m4
+  m4/open-cloexec.m4
+  m4/open.m4
   m4/pipe2.m4
   m4/pselect.m4
   m4/pthread_sigmask.m4
diff --git a/m4/mode_t.m4 b/m4/mode_t.m4
new file mode 100644
index 00000000000..75d372a4a8a
--- /dev/null
+++ b/m4/mode_t.m4
@@ -0,0 +1,26 @@
+# mode_t.m4 serial 2
+dnl Copyright (C) 2009-2017 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# For using mode_t, it's sufficient to use AC_TYPE_MODE_T and
+# include <sys/types.h>.
+
+# Define PROMOTED_MODE_T to the type that is the result of "default argument
+# promotion" (ISO C 6.5.2.2.(6)) of the type mode_t.
+AC_DEFUN([gl_PROMOTED_TYPE_MODE_T],
+[
+  AC_REQUIRE([AC_TYPE_MODE_T])
+  AC_CACHE_CHECK([for promoted mode_t type], [gl_cv_promoted_mode_t], [
+    dnl Assume mode_t promotes to 'int' if and only if it is smaller than 'int',
+    dnl and to itself otherwise. This assumption is not guaranteed by the ISO C
+    dnl standard, but we don't know of any real-world counterexamples.
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>]],
+      [[typedef int array[2 * (sizeof (mode_t) < sizeof (int)) - 1];]])],
+      [gl_cv_promoted_mode_t='int'],
+      [gl_cv_promoted_mode_t='mode_t'])
+  ])
+  AC_DEFINE_UNQUOTED([PROMOTED_MODE_T], [$gl_cv_promoted_mode_t],
+    [Define to the type that is the result of default argument promotions of type mode_t.])
+])
diff --git a/m4/open-cloexec.m4 b/m4/open-cloexec.m4
new file mode 100644
index 00000000000..897af66910f
--- /dev/null
+++ b/m4/open-cloexec.m4
@@ -0,0 +1,21 @@
+# Test whether O_CLOEXEC is defined.
+
+dnl Copyright 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,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_PREPROC_O_CLOEXEC],
+[
+  AC_CACHE_CHECK([for O_CLOEXEC],
+    [gl_cv_macro_O_CLOEXEC],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[#include <fcntl.h>
+                          #ifndef O_CLOEXEC
+                            choke me;
+                          #endif
+                        ]],
+                        [[return O_CLOEXEC;]])],
+       [gl_cv_macro_O_CLOEXEC=yes],
+       [gl_cv_macro_O_CLOEXEC=no])])
+])
diff --git a/m4/open.m4 b/m4/open.m4
new file mode 100644
index 00000000000..68253e15ffd
--- /dev/null
+++ b/m4/open.m4
@@ -0,0 +1,95 @@
+# open.m4 serial 15
+dnl Copyright (C) 2007-2017 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_OPEN],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PREPROC_O_CLOEXEC])
+  case "$host_os" in
+    mingw* | pw*)
+      REPLACE_OPEN=1
+      ;;
+    *)
+      dnl open("foo/") should not create a file when the file name has a
+      dnl trailing slash.  FreeBSD only has the problem on symlinks.
+      AC_CHECK_FUNCS_ONCE([lstat])
+      if test "$gl_cv_macro_O_CLOEXEC" != yes; then
+        REPLACE_OPEN=1
+      fi
+      AC_CACHE_CHECK([whether open recognizes a trailing slash],
+        [gl_cv_func_open_slash],
+        [# Assume that if we have lstat, we can also check symlinks.
+          if test $ac_cv_func_lstat = yes; then
+            touch conftest.tmp
+            ln -s conftest.tmp conftest.lnk
+          fi
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#include <fcntl.h>
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+int main ()
+{
+  int result = 0;
+#if HAVE_LSTAT
+  if (open ("conftest.lnk/", O_RDONLY) != -1)
+    result |= 1;
+#endif
+  if (open ("conftest.sl/", O_CREAT, 0600) >= 0)
+    result |= 2;
+  return result;
+}]])],
+            [gl_cv_func_open_slash=yes],
+            [gl_cv_func_open_slash=no],
+            [
+changequote(,)dnl
+             case "$host_os" in
+               freebsd* | aix* | hpux* | solaris2.[0-9] | solaris2.[0-9].*)
+                 gl_cv_func_open_slash="guessing no" ;;
+               *)
+                 gl_cv_func_open_slash="guessing yes" ;;
+             esac
+changequote([,])dnl
+            ])
+          rm -f conftest.sl conftest.tmp conftest.lnk
+        ])
+      case "$gl_cv_func_open_slash" in
+        *no)
+          AC_DEFINE([OPEN_TRAILING_SLASH_BUG], [1],
+            [Define to 1 if open() fails to recognize a trailing slash.])
+          REPLACE_OPEN=1
+          ;;
+      esac
+      ;;
+  esac
+  dnl Replace open() for supporting the gnulib-defined fchdir() function,
+  dnl to keep fchdir's bookkeeping up-to-date.
+  m4_ifdef([gl_FUNC_FCHDIR], [
+    if test $REPLACE_OPEN = 0; then
+      gl_TEST_FCHDIR
+      if test $HAVE_FCHDIR = 0; then
+        REPLACE_OPEN=1
+      fi
+    fi
+  ])
+  dnl Replace open() for supporting the gnulib-defined O_NONBLOCK flag.
+  m4_ifdef([gl_NONBLOCKING_IO], [
+    if test $REPLACE_OPEN = 0; then
+      gl_NONBLOCKING_IO
+      if test $gl_cv_have_open_O_NONBLOCK != yes; then
+        REPLACE_OPEN=1
+      fi
+    fi
+  ])
+])
+
+# Prerequisites of lib/open.c.
+AC_DEFUN([gl_PREREQ_OPEN],
+[
+  AC_REQUIRE([gl_PROMOTED_TYPE_MODE_T])
+  :
+])
diff --git a/m4/stdlib_h.m4 b/m4/stdlib_h.m4
index 110fe2d1a9f..ec4a058154b 100644
--- a/m4/stdlib_h.m4
+++ b/m4/stdlib_h.m4
@@ -21,9 +21,9 @@ AC_DEFUN([gl_STDLIB_H],
 #endif
     ]], [_Exit atoll canonicalize_file_name getloadavg getsubopt grantpt
     initstate initstate_r mkdtemp mkostemp mkostemps mkstemp mkstemps
-    posix_openpt ptsname ptsname_r qsort_r random random_r realpath rpmatch
-    secure_getenv setenv setstate setstate_r srandom srandom_r
-    strtod strtoll strtoull unlockpt unsetenv])
+    posix_openpt ptsname ptsname_r qsort_r random random_r reallocarray
+    realpath rpmatch secure_getenv setenv setstate setstate_r srandom
+    srandom_r strtod strtoll strtoull unlockpt unsetenv])
 ])
 
 AC_DEFUN([gl_STDLIB_MODULE_INDICATOR],
@@ -58,6 +58,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   GNULIB_QSORT_R=0;       AC_SUBST([GNULIB_QSORT_R])
   GNULIB_RANDOM=0;        AC_SUBST([GNULIB_RANDOM])
   GNULIB_RANDOM_R=0;      AC_SUBST([GNULIB_RANDOM_R])
+  GNULIB_REALLOCARRAY=0;  AC_SUBST([GNULIB_REALLOCARRAY])
   GNULIB_REALLOC_POSIX=0; AC_SUBST([GNULIB_REALLOC_POSIX])
   GNULIB_REALPATH=0;      AC_SUBST([GNULIB_REALPATH])
   GNULIB_RPMATCH=0;       AC_SUBST([GNULIB_RPMATCH])
@@ -89,6 +90,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
   HAVE_RANDOM=1;             AC_SUBST([HAVE_RANDOM])
   HAVE_RANDOM_H=1;           AC_SUBST([HAVE_RANDOM_H])
   HAVE_RANDOM_R=1;           AC_SUBST([HAVE_RANDOM_R])
+  HAVE_REALLOCARRAY=1;       AC_SUBST([HAVE_REALLOCARRAY])
   HAVE_REALPATH=1;           AC_SUBST([HAVE_REALPATH])
   HAVE_RPMATCH=1;            AC_SUBST([HAVE_RPMATCH])
   HAVE_SECURE_GETENV=1;      AC_SUBST([HAVE_SECURE_GETENV])
diff --git a/src/filelock.c b/src/filelock.c
index 3d6941695ae..fec9bc044ae 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -403,8 +403,6 @@ create_lock_file (char *lfname, char *lock_info_str, bool force)
       else
         {
           ptrdiff_t lock_info_len;
-          if (! O_CLOEXEC)
-            fcntl (fd, F_SETFD, FD_CLOEXEC);
           lock_info_len = strlen (lock_info_str);
           err = 0;
           if (emacs_write (fd, lock_info_str, lock_info_len) != lock_info_len
diff --git a/src/sysdep.c b/src/sysdep.c
index 2e18a419e3f..12e9c83ee90 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -2393,8 +2393,6 @@ emacs_open (const char *file, int oflags, int mode)
   oflags |= O_CLOEXEC;
   while ((fd = open (file, oflags, mode)) < 0 && errno == EINTR)
     maybe_quit ();
-  if (! O_CLOEXEC && 0 <= fd)
-    fcntl (fd, F_SETFD, FD_CLOEXEC);
   return fd;
 }
 
@@ -2436,13 +2434,7 @@ emacs_pipe (int fd[2])
 #ifdef MSDOS
   return pipe (fd);
 #else  /* !MSDOS */
-  int result = pipe2 (fd, O_BINARY | O_CLOEXEC);
-  if (! O_CLOEXEC && result == 0)
-    {
-      fcntl (fd[0], F_SETFD, FD_CLOEXEC);
-      fcntl (fd[1], F_SETFD, FD_CLOEXEC);
-    }
-  return result;
+  return pipe2 (fd, O_BINARY | O_CLOEXEC);
 #endif  /* !MSDOS */
 }