Add renameat2 function [BZ #17662]

The implementation falls back to renameat if renameat2 is not available
in the kernel (or in the kernel headers) and the flags argument is zero.
Without kernel support, a non-zero argument returns EINVAL, not ENOSYS.
This mirrors what the kernel does for invalid renameat2 flags.

45 files changed, 400 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 2e8308e191..27927257ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,34 @@
+2018-07-05  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ # 17662]
+	* libio/stdio.h [__USE_GNU] (RENAME_NOREPLACE, RENAME_EXCHANGE)
+	(RENAME_WHITEOUT): Define.
+	[__USE_GNU] (renameat2): Declare.
+	* stdio-common/Makefile (routines): Add renameat2.
+	(tests): Add tst-renameat2.
+	* stdio-common/Versions (GLIBC_2_28): Export renameat2.
+	* stdio-common/renameat2.c: New file.
+	* stdio-common/tst-renameat2.c: Likewise.
+	* sysdeps/unix/sysv/linux/renameat2.c: Likewise.
+	* manual/filesys.texi (Temporary Files): Note that renameat2 is
+	undocumented.
+	* sysdeps/unix/sysv/linux/kernel-features.h
+	[__LINUX_KERNEL_VERSION >= 0x030F00] (__ASSUME_RENAMEAT2): Define.
+	* sysdeps/unix/sysv/linux/alpha/kernel-features.h
+	[__LINUX_KERNEL_VERSION < 0x031100] (__ASSUME_RENAMEAT2): Undefine.
+	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
+	[__LINUX_KERNEL_VERSION < 0x031100] (__ASSUME_RENAMEAT2): Undefine.
+	* sysdeps/unix/sysv/linux/sh/kernel-features.h
+	[__LINUX_KERNEL_VERSION < 0x040800] (__ASSUME_RENAMEAT2): Undefine.
+	* sysdeps/unix/sysv/linux/sparc/kernel-features.h
+	[__LINUX_KERNEL_VERSION < 0x031000] (__ASSUME_RENAMEAT2): Undefine.
+	* include/stdio.h (__renameat): Add alias for renameat.
+	* stdio-common/renameat.c (__renameat): Rename from renameat.
+	Add hidden definition and alias.
+	* sysdeps/unix/sysv/linux/renameat.c: Likewise.
+	* sysdeps/mach/hurd/renameat.c: Likewise.
+	* sysdeps/**/libc*.abilist: Add renameat2.
+
 2018-07-04  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* posix/bug-regex33.c: Fix build after regex sync.
diff --git a/NEWS b/NEWS
index b1ce067d27..5d253910b5 100644
--- a/NEWS
+++ b/NEWS
@@ -39,6 +39,15 @@ Major new features:
 * Building and running on GNU/Hurd systems now works without out-of-tree
   patches.
 
+* The renameat2 function has been added, a variant of the renameat function
+  which has a flags argument.  If the flags are zero, the renameat2 function
+  acts like renameat.  If the flag is not zero and there is no kernel
+  support for renameat2, the function will fail with an errno value of
+  EINVAL.  This is different from the existing gnulib function renameatu,
+  which performs a plain rename operation in case of a RENAME_NOREPLACE
+  flags and a non-existing destination (and therefore has a race condition
+  that can clobber the destination inadvertently).
+
 * IDN domain names in getaddrinfo and getnameinfo now use the system libidn2
   library if installed.  libidn2 version 2.0.5 or later is recommended.  If
   libidn2 is not available, internationalized domain names are not encoded
diff --git a/include/stdio.h b/include/stdio.h
index f140813ad6..3ba0edc924 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -237,5 +237,8 @@ __putc_unlocked (int __c, FILE *__stream)
 }
 #  endif
 
+extern __typeof (renameat) __renameat;
+libc_hidden_proto (__renameat)
+
 # endif /* not _ISOMAC */
 #endif /* stdio.h */
diff --git a/libio/stdio.h b/libio/stdio.h
index 731f8e56f4..739e08610d 100644
--- a/libio/stdio.h
+++ b/libio/stdio.h
@@ -153,6 +153,18 @@ extern int renameat (int __oldfd, const char *__old, int __newfd,
 		     const char *__new) __THROW;
 #endif
 
+#ifdef __USE_GNU
+/* Flags for renameat2.  */
+# define RENAME_NOREPLACE (1 << 0)
+# define RENAME_EXCHANGE (1 << 1)
+# define RENAME_WHITEOUT (1 << 2)
+
+/* Rename file OLD relative to OLDFD to NEW relative to NEWFD, with
+   additional flags.  */
+extern int renameat2 (int __oldfd, const char *__old, int __newfd,
+		      const char *__new, unsigned int __flags) __THROW;
+#endif
+
 /* Create a temporary file and open it read/write.
 
    This function is a possible cancellation point and therefore not
diff --git a/manual/filesys.texi b/manual/filesys.texi
index cc70a6b7ee..db2f1041de 100644
--- a/manual/filesys.texi
+++ b/manual/filesys.texi
@@ -3552,6 +3552,7 @@ The @code{mkdtemp} function comes from OpenBSD.
 @c open_by_handle_at
 @c readlinkat
 @c renameat
+@c renameat2
 @c scandirat
 @c symlinkat
 @c unlinkat
diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index 96bd7c303a..a10f12ab3c 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -35,7 +35,7 @@ routines	:=							      \
 	perror psignal							      \
 	tmpfile tmpfile64 tmpnam tmpnam_r tempnam tempname		      \
 	getline getw putw						      \
-	remove rename renameat						      \
+	remove rename renameat renameat2				      \
 	flockfile ftrylockfile funlockfile				      \
 	isoc99_scanf isoc99_vscanf isoc99_fscanf isoc99_vfscanf isoc99_sscanf \
 	isoc99_vsscanf							      \
@@ -62,6 +62,7 @@ tests := tstscanf test_rdwr test-popen tstgetln test-fseek \
 	 tst-vfprintf-user-type \
 	 tst-vfprintf-mbs-prec \
 	 tst-scanf-round \
+	 tst-renameat2 \
 
 test-srcs = tst-unbputc tst-printf tst-printfsz-islongdouble
 
diff --git a/stdio-common/Versions b/stdio-common/Versions
index 5016f69c20..b8217578c8 100644
--- a/stdio-common/Versions
+++ b/stdio-common/Versions
@@ -57,6 +57,9 @@ libc {
     psiginfo;
     register_printf_modifier; register_printf_type; register_printf_specifier;
   }
+  GLIBC_2.28 {
+    renameat2;
+  }
   GLIBC_PRIVATE {
     # global variables
     _itoa_lower_digits;
diff --git a/stdio-common/renameat.c b/stdio-common/renameat.c
index 2180b87bdf..98c8f1d18b 100644
--- a/stdio-common/renameat.c
+++ b/stdio-common/renameat.c
@@ -22,7 +22,7 @@
 
 /* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */
 int
-renameat (int oldfd, const char *old, int newfd, const char *new)
+__renameat (int oldfd, const char *old, int newfd, const char *new)
 {
   if ((oldfd < 0 && oldfd != AT_FDCWD) || (newfd < 0 && newfd != AT_FDCWD))
     {
@@ -40,5 +40,6 @@ renameat (int oldfd, const char *old, int newfd, const char *new)
   return -1;
 }
 
-
+libc_hidden_def (__renameat)
+weak_alias (__renameat, renameat)
 stub_warning (renameat)
diff --git a/stdio-common/renameat2.c b/stdio-common/renameat2.c
new file mode 100644
index 0000000000..c2cedcd2cb
--- /dev/null
+++ b/stdio-common/renameat2.c
@@ -0,0 +1,30 @@
+/* Generic implementation of the renameat function.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdio.h>
+
+int
+renameat2 (int oldfd, const char *old, int newfd, const char *new,
+           unsigned int flags)
+{
+  if (flags == 0)
+    return __renameat (oldfd, old, newfd, new);
+  __set_errno (EINVAL);
+  return -1;
+}
diff --git a/stdio-common/tst-renameat2.c b/stdio-common/tst-renameat2.c
new file mode 100644
index 0000000000..958b0918d6
--- /dev/null
+++ b/stdio-common/tst-renameat2.c
@@ -0,0 +1,204 @@
+/* Linux implementation for renameat2 function.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <array_length.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+/* Directory with the temporary files.  */
+static char *directory;
+static int directory_fd;
+
+/* Paths within that directory.  */
+static char *old_path;          /* File is called "old".  */
+static char *new_path;          /* File is called "new".  */
+
+/* Subdirectory within the directory above.  */
+static char *subdirectory;
+int subdirectory_fd;
+
+/* And a pathname in that directory (called "file").  */
+static char *subdir_path;
+
+static void
+prepare (int argc, char **argv)
+{
+  directory = support_create_temp_directory ("tst-renameat2-");
+  directory_fd = xopen (directory, O_RDONLY | O_DIRECTORY, 0);
+  old_path = xasprintf ("%s/old", directory);
+  add_temp_file (old_path);
+  new_path = xasprintf ("%s/new", directory);
+  add_temp_file (new_path);
+  subdirectory = xasprintf ("%s/subdir", directory);
+  xmkdir (subdirectory, 0777);
+  add_temp_file (subdirectory);
+  subdirectory_fd = xopen (subdirectory, O_RDONLY | O_DIRECTORY, 0);
+  subdir_path = xasprintf ("%s/file", subdirectory);
+  add_temp_file (subdir_path);
+}
+
+/* Delete all files, preparing a clean slate for the next test.  */
+static void
+delete_all_files (void)
+{
+  char *files[] = { old_path, new_path, subdir_path };
+  for (size_t i = 0; i < array_length (files); ++i)
+    if (unlink (files[i]) != 0 && errno != ENOENT)
+      FAIL_EXIT1 ("unlink (\"%s\"): %m", files[i]);
+}
+
+/* Return true if PATH exists in the file system.  */
+static bool
+file_exists (const char *path)
+{
+  return access (path, F_OK) == 0;
+}
+
+/* Check that PATH exists and has size EXPECTED_SIZE.  */
+static void
+check_size (const char *path, off64_t expected_size)
+{
+  struct stat64 st;
+  xstat (path, &st);
+  if (st.st_size != expected_size)
+    FAIL_EXIT1 ("file \"%s\": expected size %lld, actual size %lld",
+                path, (unsigned long long int) expected_size,
+                (unsigned long long int) st.st_size);
+}
+
+/* Rename tests where the target does not exist.  */
+static void
+rename_without_existing_target (unsigned int flags)
+{
+  delete_all_files ();
+  support_write_file_string (old_path, "");
+  TEST_COMPARE (renameat2 (AT_FDCWD, old_path, AT_FDCWD, new_path, flags), 0);
+  TEST_VERIFY (!file_exists (old_path));
+  TEST_VERIFY (file_exists (new_path));
+
+  delete_all_files ();
+  support_write_file_string (old_path, "");
+  TEST_COMPARE (renameat2 (directory_fd, "old", AT_FDCWD, new_path, flags), 0);
+  TEST_VERIFY (!file_exists (old_path));
+  TEST_VERIFY (file_exists (new_path));
+
+  delete_all_files ();
+  support_write_file_string (old_path, "");
+  TEST_COMPARE (renameat2 (directory_fd, "old", subdirectory_fd, "file", 0),
+                0);
+  TEST_VERIFY (!file_exists (old_path));
+  TEST_VERIFY (file_exists (subdir_path));
+}
+
+static int
+do_test (void)
+{
+  /* Tests with zero flags argument.  These are expected to succeed
+     because this renameat2 variant can be implemented with
+     renameat.  */
+  rename_without_existing_target (0);
+
+  /* renameat2 without flags replaces an existing destination.  */
+  delete_all_files ();
+  support_write_file_string (old_path, "123");
+  support_write_file_string (new_path, "1234");
+  TEST_COMPARE (renameat2 (AT_FDCWD, old_path, AT_FDCWD, new_path, 0), 0);
+  TEST_VERIFY (!file_exists (old_path));
+  check_size (new_path, 3);
+
+  /* Now we need to check for kernel support of renameat2 with
+     flags.  */
+  delete_all_files ();
+  support_write_file_string (old_path, "");
+  if (renameat2 (AT_FDCWD, old_path, AT_FDCWD, new_path, RENAME_NOREPLACE)
+      != 0)
+    {
+      if (errno == EINVAL)
+        puts ("warning: no support for renameat2 with flags");
+      else
+        FAIL_EXIT1 ("renameat2 probe failed: %m");
+    }
+  else
+    {
+      /* We have full renameat2 support.  */
+      rename_without_existing_target (RENAME_NOREPLACE);
+
+      /* Now test RENAME_NOREPLACE with an existing target.  */
+      delete_all_files ();
+      support_write_file_string (old_path, "123");
+      support_write_file_string (new_path, "1234");
+      TEST_COMPARE (renameat2 (AT_FDCWD, old_path, AT_FDCWD, new_path,
+                               RENAME_NOREPLACE), -1);
+      TEST_COMPARE (errno, EEXIST);
+      check_size (old_path, 3);
+      check_size (new_path, 4);
+
+      delete_all_files ();
+      support_write_file_string (old_path, "123");
+      support_write_file_string (new_path, "1234");
+      TEST_COMPARE (renameat2 (directory_fd, "old", AT_FDCWD, new_path,
+                               RENAME_NOREPLACE), -1);
+      TEST_COMPARE (errno, EEXIST);
+      check_size (old_path, 3);
+      check_size (new_path, 4);
+
+      delete_all_files ();
+      support_write_file_string (old_path, "123");
+      support_write_file_string (subdir_path, "1234");
+      TEST_COMPARE (renameat2 (directory_fd, "old", subdirectory_fd, "file",
+                               RENAME_NOREPLACE), -1);
+      TEST_COMPARE (errno, EEXIST);
+      check_size (old_path, 3);
+      check_size (subdir_path, 4);
+
+      /* The flag combination of RENAME_NOREPLACE and RENAME_EXCHANGE
+         is invalid.  */
+      TEST_COMPARE (renameat2 (directory_fd, "ignored",
+                               subdirectory_fd, "ignored",
+                               RENAME_NOREPLACE | RENAME_EXCHANGE), -1);
+      TEST_COMPARE (errno, EINVAL);
+    }
+
+  /* Create all the pathnames to avoid warnings from the test
+     harness.  */
+  support_write_file_string (old_path, "");
+  support_write_file_string (new_path, "");
+  support_write_file_string (subdir_path, "");
+
+  free (directory);
+  free (subdirectory);
+  free (old_path);
+  free (new_path);
+  free (subdir_path);
+
+  xclose (directory_fd);
+  xclose (subdirectory_fd);
+
+  return 0;
+}
+
+#define PREPARE prepare
+#include <support/test-driver.c>
diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
index 57091fce00..a9089d9064 100644
--- a/sysdeps/mach/hurd/i386/libc.abilist
+++ b/sysdeps/mach/hurd/i386/libc.abilist
@@ -2034,6 +2034,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/mach/hurd/renameat.c b/sysdeps/mach/hurd/renameat.c
index 43609600d9..7985763f73 100644
--- a/sysdeps/mach/hurd/renameat.c
+++ b/sysdeps/mach/hurd/renameat.c
@@ -22,7 +22,7 @@
 
 /* Rename the file OLD relative to OLDFD to NEW relative to NEWFD.  */
 int
-renameat (int oldfd, const char *old, int newfd, const char *new)
+__renameat (int oldfd, const char *old, int newfd, const char *new)
 {
   error_t err;
   file_t olddir, newdir;
@@ -45,3 +45,5 @@ renameat (int oldfd, const char *old, int newfd, const char *new)
     return __hurd_fail (err);
   return 0;
 }
+libc_hidden_def (__renameat)
+weak_alias (__renameat, renameat)
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index 884d0dfa95..7a272a19bb 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2132,3 +2132,4 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
diff --git a/sysdeps/unix/sysv/linux/alpha/kernel-features.h b/sysdeps/unix/sysv/linux/alpha/kernel-features.h
index c2d4a9f55b..5781cffd5a 100644
--- a/sysdeps/unix/sysv/linux/alpha/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/alpha/kernel-features.h
@@ -35,6 +35,11 @@
 #define __ASSUME_RECV_SYSCALL	1
 #define __ASSUME_SEND_SYSCALL	1
 
+/* Support for the renameat2 syscall was added in 3.17.  */
+#if __LINUX_KERNEL_VERSION < 0x031100
+# undef __ASSUME_RENAMEAT2
+#endif
+
 /* Support for the execveat syscall was added in 4.2.  */
 #if __LINUX_KERNEL_VERSION < 0x040200
 # undef __ASSUME_EXECVEAT
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index 28d54b9794..23fec55d97 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2027,6 +2027,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
index dfde3bd725..b203160889 100644
--- a/sysdeps/unix/sysv/linux/arm/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
@@ -117,6 +117,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
 GLIBC_2.4 _IO_2_1_stdin_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 06b00f730a..64809ca403 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -1874,6 +1874,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index 1c1cc00d40..4a87f62ad9 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2039,6 +2039,7 @@ GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index f6e17a005f..6bdd0d0443 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -1908,6 +1908,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index b90ea30195..86fc66574b 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -97,6 +97,11 @@
    implementation based on p{read,write}v and returning an error for
    non supported flags.  */
 
+/* Support for the renameat2 system call was added in kernel 3.15.  */
+#if __LINUX_KERNEL_VERSION >= 0x030F00
+# define __ASSUME_RENAMEAT2
+#endif
+
 /* Support for the execveat syscall was added in 3.19.  */
 #if __LINUX_KERNEL_VERSION >= 0x031300
 # define __ASSUME_EXECVEAT	1
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index ee054a618d..3226f916eb 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -118,6 +118,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.4 _Exit F
 GLIBC_2.4 _IO_2_1_stderr_ D 0x98
 GLIBC_2.4 _IO_2_1_stdin_ D 0x98
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index 227a0581cb..b1074eeed1 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -1983,6 +1983,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
index b13b863f06..7db3d05636 100644
--- a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
@@ -48,6 +48,11 @@
 # undef __ASSUME_SENDMMSG_SYSCALL
 #endif
 
+/* Support for the renameat2 syscall was added in 3.17.  */
+#if __LINUX_KERNEL_VERSION < 0x031100
+# undef __ASSUME_RENAMEAT2
+#endif
+
 /* Support for the execveat syscall was added in 4.0.  */
 #if __LINUX_KERNEL_VERSION < 0x040000
 # undef __ASSUME_EXECVEAT
diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
index 18781b3017..b52fc7d6f7 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
@@ -2124,3 +2124,4 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 2d86989cf2..718c74262a 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -1961,6 +1961,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index b8b113e1a5..9b218a9435 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -1959,6 +1959,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index 6a3cd13e2d..5a90ab83e7 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -1967,6 +1967,7 @@ GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index 596ec05379..3005fc9500 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -1962,6 +1962,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index 8da18eed57..a87fbbeb6b 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2165,3 +2165,4 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index 555751eb12..d56f776a52 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -1987,6 +1987,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index 80324e41aa..2b5337aab6 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -1991,6 +1991,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
index 97b1d354af..d0dfde3897 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
@@ -2222,3 +2222,4 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
index 15be314921..d505ae0e7d 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
@@ -117,6 +117,7 @@ GLIBC_2.27 wcstof32x_l F
 GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 _Exit F
 GLIBC_2.3 _IO_2_1_stderr_ D 0xe0
 GLIBC_2.3 _IO_2_1_stdin_ D 0xe0
diff --git a/sysdeps/unix/sysv/linux/renameat.c b/sysdeps/unix/sysv/linux/renameat.c
index 034432b934..f85c5ae0ec 100644
--- a/sysdeps/unix/sysv/linux/renameat.c
+++ b/sysdeps/unix/sysv/linux/renameat.c
@@ -22,7 +22,7 @@
 #include <errno.h>
 
 int
-renameat (int oldfd, const char *old, int newfd, const char *new)
+__renameat (int oldfd, const char *old, int newfd, const char *new)
 {
 #ifdef __NR_renameat
   return INLINE_SYSCALL_CALL (renameat, oldfd, old, newfd, new);
@@ -30,3 +30,5 @@ renameat (int oldfd, const char *old, int newfd, const char *new)
   return INLINE_SYSCALL_CALL (renameat2, oldfd, old, newfd, new, 0);
 #endif
 }
+libc_hidden_def (__renameat)
+weak_alias (__renameat, renameat)
diff --git a/sysdeps/unix/sysv/linux/renameat2.c b/sysdeps/unix/sysv/linux/renameat2.c
new file mode 100644
index 0000000000..919bb2a0d4
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/renameat2.c
@@ -0,0 +1,44 @@
+/* Linux implementation for renameat2 function.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdio.h>
+#include <sysdep.h>
+
+int
+renameat2 (int oldfd, const char *old, int newfd, const char *new,
+           unsigned int flags)
+{
+#if !defined (__NR_renameat) || defined (__ASSUME_RENAMEAT2)
+  return INLINE_SYSCALL_CALL (renameat2, oldfd, old, newfd, new, flags);
+#else
+  if (flags == 0)
+    return __renameat (oldfd, old, newfd, new);
+# ifdef __NR_renameat2
+  /* For non-zero flags, try the renameat2 system call.  */
+  int ret = INLINE_SYSCALL_CALL (renameat2, oldfd, old, newfd, new, flags);
+  if (ret != -1 || errno != ENOSYS)
+    /* Preserve non-error/non-ENOSYS return values.  */
+    return ret;
+# endif
+  /* No kernel (header) support for renameat2.  All flags are
+     unknown.  */
+  __set_errno (EINVAL);
+  return -1;
+#endif
+}
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
index 436b992251..33f751abc0 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
@@ -2094,3 +2094,4 @@ GLIBC_2.27 xencrypt F
 GLIBC_2.27 xprt_register F
 GLIBC_2.27 xprt_unregister F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index f66715f0c9..c4ec93ff43 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -1996,6 +1996,7 @@ GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index bd6242861b..2a6a0abde8 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -1901,6 +1901,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/sh/kernel-features.h b/sysdeps/unix/sysv/linux/sh/kernel-features.h
index b82d032e6b..05b7dcd037 100644
--- a/sysdeps/unix/sysv/linux/sh/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/sh/kernel-features.h
@@ -51,4 +51,9 @@
 /* sh only supports ipc syscall.  */
 #undef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
 
+/* Support for the renameat2 syscall was added in 4.8.  */
+#if __LINUX_KERNEL_VERSION < 0x040800
+# undef __ASSUME_RENAMEAT2
+#endif
+
 #endif
diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
index f2f070fbce..8de0d1711a 100644
--- a/sysdeps/unix/sysv/linux/sh/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
@@ -1878,6 +1878,7 @@ GLIBC_2.27 wcstof64 F
 GLIBC_2.27 wcstof64_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/kernel-features.h b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
index 64d714036e..91990a716f 100644
--- a/sysdeps/unix/sysv/linux/sparc/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
@@ -41,6 +41,11 @@
 /* sparc only supports ipc syscall.  */
 #undef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
 
+/* Support for the renameat2 syscall was added in 3.16.  */
+#if __LINUX_KERNEL_VERSION < 0x031000
+# undef __ASSUME_RENAMEAT2
+#endif
+
 /* SPARC kernel Kconfig does not define CONFIG_CLONE_BACKWARDS, however it
    has the same ABI as if it did, implemented by sparc-specific code
    (sparc_do_fork).
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index 265087f6a8..9858460c9f 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -1990,6 +1990,7 @@ GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index 16a69812cb..a22b8fb7ca 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -1931,6 +1931,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index fa8c198d13..d5d71cccba 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -1889,6 +1889,7 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F
 GLIBC_2.3 __ctype_b_loc F
 GLIBC_2.3 __ctype_tolower_loc F
 GLIBC_2.3 __ctype_toupper_loc F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index 2536971682..e6ad42440e 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2140,3 +2140,4 @@ GLIBC_2.27 wcstof64_l F
 GLIBC_2.27 wcstof64x F
 GLIBC_2.27 wcstof64x_l F
 GLIBC_2.28 fcntl64 F
+GLIBC_2.28 renameat2 F