Patchwork copy_file_range: New function to copy file data

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Submitter Florian Weimer
Date Dec. 5, 2017, 2:03 p.m.
Message ID <16de12bf-eab1-b69c-cd58-a6dd24ad409f@redhat.com>
Download mbox | patch
Permalink /patch/24737/
State New
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Comments

Florian Weimer - Dec. 5, 2017, 2:03 p.m.
The attached version of the patch fixes a few 32-bit issues in the code 
(non-64 functions being called, and size_t-to-off64_t conversion issue). 
  I renamed the -common.c file into -compat.c, for consistency with how 
the file is used.

It also drops the zero-as-ENOSPC special case Andreas recognized as 
unnecessary.

Thanks,
Florian
Florian Weimer - Dec. 14, 2017, 2:26 p.m.
On 12/05/2017 03:03 PM, Florian Weimer wrote:
> 2017-12-05  Florian Weimer<fweimer@redhat.com>
> 
> 	* io/Makefile (routines): Add copy_file_range.
> 	(tests): Add tst-copy_file_range.
> 	(tests-static, tests-internal): Add tst-copy_file_range-compat.
> 	* io/Versions (GLIBC_2.27): Export copy_file_range.
> 	* io/copy_file_range-compat.c: New file.
> 	* io/copy_file_range.c: Likewise.
> 	* io/tst-copy_file_range-compat.c: Likewise.
> 	* io/tst-copy_file_range.c: Likewise.
> 	* manual/llio.texi (Copying File Data): New section.
> 	* posix/unistd.h [__USE_GNU] (copy_file_range): Declare.
> 	* support/Makefile (libsupport-routines): Add support-xfstat,
> 	xftruncate, xlseek.
> 	* support/support-xfstat.c: New file.
> 	* support/xftruncate.c: Likewise.
> 	* support/xlseek.c: Likewise.
> 	* support/xunistd.h (xfstat, xftruncate, xlseek): Declare.
> 	* sysdeps/unix/sysv/linux/**.abilist: Update.
> 	* sysdeps/unix/sysv/linux/copy_file_range.c: New file.

Ping?

<https://sourceware.org/ml/libc-alpha/2017-12/msg00122.html>

Thanks,
Florian

Patch

Subject: [PATCH] copy_file_range: New function to copy file data
To: libc-alpha@sourceware.org

The semantics are based on the Linux system call, but a very close
emulation in user space is provided.

2017-12-05  Florian Weimer  <fweimer@redhat.com>

	* io/Makefile (routines): Add copy_file_range.
	(tests): Add tst-copy_file_range.
	(tests-static, tests-internal): Add tst-copy_file_range-compat.
	* io/Versions (GLIBC_2.27): Export copy_file_range.
	* io/copy_file_range-compat.c: New file.
	* io/copy_file_range.c: Likewise.
	* io/tst-copy_file_range-compat.c: Likewise.
	* io/tst-copy_file_range.c: Likewise.
	* manual/llio.texi (Copying File Data): New section.
	* posix/unistd.h [__USE_GNU] (copy_file_range): Declare.
	* support/Makefile (libsupport-routines): Add support-xfstat,
	xftruncate, xlseek.
	* support/support-xfstat.c: New file.
	* support/xftruncate.c: Likewise.
	* support/xlseek.c: Likewise.
	* support/xunistd.h (xfstat, xftruncate, xlseek): Declare.
	* sysdeps/unix/sysv/linux/**.abilist: Update.
	* sysdeps/unix/sysv/linux/copy_file_range.c: New file.

diff --git a/io/Makefile b/io/Makefile
index 2f26bf56db..f2f0f0d040 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -52,7 +52,7 @@  routines :=								\
 	ftw ftw64 fts fts64 poll ppoll					\
 	posix_fadvise posix_fadvise64					\
 	posix_fallocate posix_fallocate64				\
-	sendfile sendfile64 \
+	sendfile sendfile64 copy_file_range 				\
 	utimensat futimens
 
 # These routines will be omitted from the libc shared object.
@@ -70,7 +70,13 @@  tests		:= test-utime test-stat test-stat2 test-lfs tst-getcwd \
 		   tst-symlinkat tst-linkat tst-readlinkat tst-mkdirat \
 		   tst-mknodat tst-mkfifoat tst-ttyname_r bug-ftw5 \
 		   tst-posix_fallocate tst-posix_fallocate64 \
-		   tst-fts tst-fts-lfs tst-open-tmpfile
+		   tst-fts tst-fts-lfs tst-open-tmpfile \
+		   tst-copy_file_range \
+
+# This test includes the compat implementation of copy_file_range,
+# which uses internal, unexported libc functions.
+tests-static += tst-copy_file_range-compat
+tests-internal += tst-copy_file_range-compat
 
 ifeq ($(run-built-tests),yes)
 tests-special += $(objpfx)ftwtest.out
diff --git a/io/Versions b/io/Versions
index 64316cd025..98898cb9d5 100644
--- a/io/Versions
+++ b/io/Versions
@@ -125,4 +125,7 @@  libc {
   GLIBC_2.23 {
     fts64_children; fts64_close; fts64_open; fts64_read; fts64_set;
   }
+  GLIBC_2.27 {
+    copy_file_range;
+  }
 }
diff --git a/io/copy_file_range-compat.c b/io/copy_file_range-compat.c
new file mode 100644
index 0000000000..ba6ea389df
--- /dev/null
+++ b/io/copy_file_range-compat.c
@@ -0,0 +1,158 @@ 
+/* Emulation of copy_file_range.
+   Copyright (C) 2017 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/>.  */
+
+/* The following macros should be defined before including this
+   file:
+
+   COPY_FILE_RANGE_DECL   Declaration specifiers for the function below.
+   COPY_FILE_RANGE        Name of the function to define.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+COPY_FILE_RANGE_DECL
+ssize_t
+COPY_FILE_RANGE (int infd, __off64_t *pinoff,
+                 int outfd, __off64_t *poutoff,
+                 size_t length, unsigned int flags)
+{
+  if (flags != 0)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  struct stat64 instat;
+  struct stat64 outstat;
+  if (fstat64 (infd, &instat) != 0 || fstat64 (outfd, &outstat) != 0)
+    return -1;
+  if (S_ISDIR (instat.st_mode) || S_ISDIR (outstat.st_mode))
+    {
+      __set_errno (EISDIR);
+      return -1;
+    }
+  if (!S_ISREG (instat.st_mode) || !S_ISREG (outstat.st_mode))
+    {
+      /* We need a regular input file so that the we can seek
+         backwards in case of a write failure.  */
+      __set_errno (EINVAL);
+      return -1;
+    }
+  if (instat.st_dev != outstat.st_dev)
+    {
+      /* Cross-device copies are not supported.  */
+      __set_errno (EXDEV);
+      return -1;
+    }
+
+  /* The output descriptor must not have O_APPEND set.  */
+  {
+    int flags = __fcntl (outfd, F_GETFL);
+    if (flags & O_APPEND)
+      {
+        __set_errno (EBADF);
+        return -1;
+      }
+  }
+
+  /* Avoid an overflow in the result.  */
+  if (length > SSIZE_MAX)
+    length = SSIZE_MAX;
+
+  /* Main copying loop.  The buffer size is arbitrary and is a
+     trade-off between stack size consumption, cache usage, and
+     amortization of system call overhead.  */
+  size_t copied = 0;
+  char buf[8192];
+  while (length > 0)
+    {
+      size_t to_read = length;
+      if (to_read > sizeof (buf))
+        to_read = sizeof (buf);
+
+      /* Fill the buffer.  */
+      ssize_t read_count;
+      if (pinoff == NULL)
+        read_count = read (infd, buf, to_read);
+      else
+        read_count = __libc_pread64 (infd, buf, to_read, *pinoff);
+      if (read_count == 0)
+        /* End of file reached prematurely.  */
+        return copied;
+      if (read_count < 0)
+        {
+          if (copied > 0)
+            /* Report the number of bytes copied so far.  */
+            return copied;
+          return -1;
+        }
+      if (pinoff != 0)
+        *pinoff += read_count;
+
+      /* Write the buffer part which was read to the destination.  */
+      char *end = buf + read_count;
+      for (char *p = buf; p < end; )
+        {
+          ssize_t write_count;
+          if (poutoff == NULL)
+            write_count = write (outfd, p, end - p);
+          else
+            write_count = __libc_pwrite64 (outfd, p, end - p, *poutoff);
+          if (write_count < 0)
+            {
+              /* Adjust the input read position to match what we have
+                 written, so that the caller can pick up after the
+                 error.  */
+              size_t written = p - buf;
+              /* NB: This needs to be signed so that we can form the
+                 negative value below.  */
+              ssize_t overread = read_count - written;
+              if (pinoff == NULL)
+                {
+                  if (overread > 0)
+                    {
+                      /* We are on an error recovery path, so we
+                         cannot deal with failure here.  */
+                      int save_errno = errno;
+                      (void) __libc_lseek64 (infd, -overread, SEEK_CUR);
+                      __set_errno (save_errno);
+                    }
+                }
+              else /* pinoff != NULL */
+                *pinoff -= overread;
+
+              if (copied > 0)
+                /* Report the number of bytes copied so far.  */
+                return copied + written;
+              return -1;
+            }
+          p += write_count;
+          if (poutoff != NULL)
+            *poutoff += write_count;
+        } /* Write loop.  */
+
+      copied += read_count;
+      length -= read_count;
+    }
+  return copied;
+}
diff --git a/io/copy_file_range.c b/io/copy_file_range.c
new file mode 100644
index 0000000000..61ee6871b4
--- /dev/null
+++ b/io/copy_file_range.c
@@ -0,0 +1,22 @@ 
+/* Generic implementation of copy_file_range.
+   Copyright (C) 2017 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/>.  */
+
+#define COPY_FILE_RANGE_DECL
+#define COPY_FILE_RANGE copy_file_range
+
+#include <io/copy_file_range-compat.c>
diff --git a/io/tst-copy_file_range-compat.c b/io/tst-copy_file_range-compat.c
new file mode 100644
index 0000000000..eb737946d9
--- /dev/null
+++ b/io/tst-copy_file_range-compat.c
@@ -0,0 +1,30 @@ 
+/* Test the fallback implementation of copy_file_range.
+   Copyright (C) 2017 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/>.  */
+
+/* Get the declaration of the official copy_of_range function.  */
+#include <unistd.h>
+
+/* Compile a local version of copy_file_range.  */
+#define COPY_FILE_RANGE_DECL static
+#define COPY_FILE_RANGE copy_file_range_compat
+#include <io/copy_file_range-compat.c>
+
+/* Re-use the test, but run it against copy_file_range_compat defined
+   above.  */
+#define copy_file_range copy_file_range_compat
+#include "tst-copy_file_range.c"
diff --git a/io/tst-copy_file_range.c b/io/tst-copy_file_range.c
new file mode 100644
index 0000000000..d7532f288a
--- /dev/null
+++ b/io/tst-copy_file_range.c
@@ -0,0 +1,730 @@ 
+/* Tests for copy_file_range.
+   Copyright (C) 2017 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 <inttypes.h>
+#include <libgen.h>
+#include <poll.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+#include <sys/mount.h>
+
+/* Boolean flags which indicate whether to use pointers with explicit
+   output flags.  */
+static int do_inoff;
+static int do_outoff;
+
+/* Name and descriptors of the input files.  Files are truncated and
+   reopened (with O_RDWR) between tests.  */
+static char *infile;
+static int infd;
+static char *outfile;
+static int outfd;
+
+/* Like the above, but on a different file system.  xdevfile can be
+   NULL if no suitable file system has been found.  */
+static char *xdevfile;
+
+/* Input and output offsets.  Set according to do_inoff and do_outoff
+   before the test.  The offsets themselves are always set to
+   zero.  */
+static off64_t inoff;
+static off64_t *pinoff;
+static off64_t outoff;
+static off64_t *poutoff;
+
+/* These are a collection of copy sizes used in tests.  The selection
+   takes into account that the fallback implementation uses an
+   internal buffer of 8192 bytes.  */
+enum { maximum_size = 99999 };
+static const int typical_sizes[] =
+  { 0, 1, 2, 3, 1024, 2048, 4096, 8191, 8192, 8193, 16383, 16384, 16385,
+    maximum_size };
+
+/* The random contents of this array can be used as a pattern to check
+   for correct write operations.  */
+static unsigned char random_data[maximum_size];
+
+/* The size chosen by the test harness.  */
+static int current_size;
+
+/* Discover the maximum file size (writable offset) for outfd.
+   Truncate outfd to length zero as a side effect.  */
+static off64_t
+find_maximum_offset (void)
+{
+  xftruncate (outfd, 0);
+  static off64_t cache = 0;
+  if (cache != 0)
+    return cache;
+
+  uint64_t upper = -1;
+  upper >>= 1;                  /* Maximum of off64_t.  */
+  TEST_VERIFY ((off64_t) upper > 0);
+  TEST_VERIFY ((off64_t) (upper + 1) < 0);
+  if (lseek64 (outfd, upper, SEEK_SET) >= 0)
+    {
+      if (write (outfd, "", 1) == 1)
+        FAIL_EXIT1 ("created a file larger than the off64_t range");
+    }
+
+  uint64_t lower = 1024 * 1024; /* A reasonable minimum file size.  */
+  /* Loop invariant: writing at lower succeeds, writing at upper fails.  */
+  while (lower + 1 < upper)
+    {
+      uint64_t middle = (lower + upper) / 2;
+      if (test_verbose > 0)
+        printf ("info: %s: remaining test range %" PRIu64 " .. %" PRIu64
+                ", probe at %" PRIu64 "\n", __func__, lower, upper, middle);
+      xftruncate (outfd, 0);
+      if (lseek64 (outfd, middle, SEEK_SET) >= 0
+          && write (outfd, "", 1) == 1)
+        lower = middle;
+      else
+        upper = middle;
+    }
+  TEST_VERIFY (lower + 1 == upper);
+  xftruncate (outfd, 0);
+  cache = lower;
+  printf ("info: maximum writable file offset: %" PRIu64 " (%" PRIx64 ")\n",
+          lower, lower);
+  return lower;
+}
+
+/* Perform a copy of a file.  */
+static void
+simple_file_copy (void)
+{
+  xwrite (infd, random_data, current_size);
+
+  int length;
+  int in_skipped; /* Expected skipped bytes in input.  */
+  if (do_inoff)
+    {
+      xlseek (infd, 1, SEEK_SET);
+      inoff = 2;
+      length = current_size - 3;
+      in_skipped = 2;
+    }
+  else
+    {
+      xlseek (infd, 3, SEEK_SET);
+      length = current_size - 5;
+      in_skipped = 3;
+    }
+  int out_skipped; /* Expected skipped bytes before the written data.  */
+  if (do_outoff)
+    {
+      xlseek (outfd, 4, SEEK_SET);
+      outoff = 5;
+      out_skipped = 5;
+    }
+  else
+    {
+      xlseek (outfd, 6, SEEK_SET);
+      length = current_size - 6;
+      out_skipped = 6;
+    }
+  if (length < 0)
+    length = 0;
+
+  TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
+                                 length, 0), length);
+  if (do_inoff)
+    {
+      TEST_COMPARE (inoff, 2 + length);
+      TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 1);
+    }
+  else
+    TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 3 + length);
+  if (do_outoff)
+    {
+      TEST_COMPARE (outoff, 5 + length);
+      TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 4);
+    }
+  else
+    TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 6 + length);
+
+  struct stat64 st;
+  xfstat (outfd, &st);
+  if (length > 0)
+    TEST_COMPARE (st.st_size, out_skipped + length);
+  else
+    {
+      /* If we did not write anything, we also did not add any
+         padding.  */
+      TEST_COMPARE (st.st_size, 0);
+      return;
+    }
+
+  xlseek (outfd, 0, SEEK_SET);
+  char *bytes = xmalloc (st.st_size);
+  TEST_COMPARE (read (outfd, bytes, st.st_size), st.st_size);
+  for (int i = 0; i < out_skipped; ++i)
+    TEST_COMPARE (bytes[i], 0);
+  TEST_VERIFY (memcmp (bytes + out_skipped, random_data + in_skipped,
+                       length) == 0);
+  free (bytes);
+}
+
+/* Test that reading from a pipe willfails.  */
+static void
+pipe_as_source (void)
+{
+  int pipefds[2];
+  xpipe (pipefds);
+
+  for (int length = 0; length < 2; ++length)
+    {
+      if (test_verbose > 0)
+        printf ("info: %s: length=%d\n", __func__, length);
+
+      /* Make sure that there is something to copy in the pipe.  */
+      xwrite (pipefds[1], "@", 1);
+
+      TEST_COMPARE (copy_file_range (pipefds[0], pinoff, outfd, poutoff,
+                                     length, 0), -1);
+      /* Linux 4.10 and later return EINVAL.  Older kernels return
+         EXDEV.  */
+      TEST_VERIFY (errno == EINVAL || errno == EXDEV);
+      TEST_COMPARE (inoff, 0);
+      TEST_COMPARE (outoff, 0);
+      TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 0);
+
+      /* Make sure that nothing was read.  */
+      char buf = 'A';
+      TEST_COMPARE (read (pipefds[0], &buf, 1), 1);
+      TEST_COMPARE (buf, '@');
+    }
+
+  xclose (pipefds[0]);
+  xclose (pipefds[1]);
+}
+
+/* Test that writing to a pipe fails.  */
+static void
+pipe_as_destination (void)
+{
+  /* Make sure that there is something to read in the input file.  */
+  xwrite (infd, "abc", 3);
+  xlseek (infd, 0, SEEK_SET);
+
+  int pipefds[2];
+  xpipe (pipefds);
+
+  for (int length = 0; length < 2; ++length)
+    {
+      if (test_verbose > 0)
+        printf ("info: %s: length=%d\n", __func__, length);
+
+      TEST_COMPARE (copy_file_range (infd, pinoff, pipefds[1], poutoff,
+                                     length, 0), -1);
+      /* Linux 4.10 and later return EINVAL.  Older kernels return
+         EXDEV.  */
+      TEST_VERIFY (errno == EINVAL || errno == EXDEV);
+      TEST_COMPARE (inoff, 0);
+      TEST_COMPARE (outoff, 0);
+      TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
+
+      /* Make sure that nothing was written.  */
+      struct pollfd pollfd = { .fd = pipefds[0], .events = POLLIN, };
+      TEST_COMPARE (poll (&pollfd, 1, 0), 0);
+    }
+
+  xclose (pipefds[0]);
+  xclose (pipefds[1]);
+}
+
+/* Test a write failure after (potentially) writing some bytes.  */
+static void
+delayed_write_failure (void)
+{
+  /* We need to write something to provoke the error.  */
+  if (current_size == 0)
+    return;
+  xwrite (infd, random_data, sizeof (random_data));
+  xlseek (infd, 0, SEEK_SET);
+
+  /* Write failure near the start.  */
+  off64_t where = find_maximum_offset ();
+  if (current_size == 1)
+    ++where;
+  outoff = where;
+  if (do_outoff)
+    xlseek (outfd, 1, SEEK_SET);
+  else
+    xlseek (outfd, where, SEEK_SET);
+  TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
+                                 sizeof (random_data), 0), -1);
+  TEST_COMPARE (errno, EINVAL);
+  TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
+  if (do_outoff)
+    TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 1);
+  else
+    TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), where);
+  TEST_COMPARE (outoff, where);
+  struct stat64 st;
+  xfstat (outfd, &st);
+  TEST_COMPARE (st.st_size, 0);
+
+  /* Write failure near the end.  */
+  if (current_size == 1)
+    /* This would be same as the first test because there is only one
+       byte.  */
+    return;
+  where = find_maximum_offset () - current_size + 1;
+  if (current_size == sizeof (random_data))
+    /* Otherwise we do not reach the non-writable byte.  */
+    ++where;
+  outoff = where;
+  if (do_outoff)
+    xlseek (outfd, 1, SEEK_SET);
+  else
+    xlseek (outfd, where, SEEK_SET);
+  ssize_t ret = copy_file_range (infd, pinoff, outfd, poutoff,
+                                 sizeof (random_data), 0);
+  if (ret < 0)
+    {
+      TEST_COMPARE (ret, -1);
+      TEST_COMPARE (errno, EINVAL);
+      xfstat (outfd, &st);
+      TEST_COMPARE (st.st_size, 0);
+    }
+  else
+    {
+      /* The first copy succeeded.  This happens in the emulation
+         because the internal buffer of limited size does not
+         necessarily cross the off64_t boundary on the first write
+         operation.  */
+      if (test_verbose > 0)
+        printf ("info:   copy_file_range (%zu) returned %zd\n",
+                sizeof (random_data), ret);
+      TEST_VERIFY (ret > 0);
+      TEST_VERIFY (ret < maximum_size);
+      xfstat (outfd, &st);
+      TEST_COMPARE (st.st_size, where + ret);
+      if (do_inoff)
+        {
+          TEST_COMPARE (inoff, ret);
+          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
+        }
+      else
+          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), ret);
+
+      char *buffer = xmalloc (ret);
+      TEST_COMPARE (pread64 (outfd, buffer, ret, where), ret);
+      TEST_VERIFY (memcmp (buffer, random_data, ret) == 0);
+      free (buffer);
+
+      /* The second copy fails.  */
+      TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
+                                     sizeof (random_data), 0), -1);
+      TEST_COMPARE (errno, EINVAL);
+    }
+}
+
+/* Test a write failure across devices.  */
+static void
+cross_device_failure (void)
+{
+  if (xdevfile == NULL)
+    /* Subtest not supported due to missing cross-device file.  */
+    return;
+
+  /* We need something to write.  */
+  xwrite (infd, random_data, sizeof (random_data));
+  xlseek (infd, 0, SEEK_SET);
+
+  int xdevfd = xopen (xdevfile, O_RDWR | O_LARGEFILE, 0);
+  TEST_COMPARE (copy_file_range (infd, pinoff, xdevfd, poutoff,
+                                 current_size, 0), -1);
+  TEST_COMPARE (errno, EXDEV);
+  TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 0);
+  struct stat64 st;
+  xfstat (xdevfd, &st);
+  TEST_COMPARE (st.st_size, 0);
+
+  xclose (xdevfd);
+}
+
+/* Try to exercise ENOSPC behavior with a tempfs file system (so that
+   we do not have to fill up a regular file system to get the error).
+   This function runs in a subprocess, so that we do not change the
+   mount namespace of the actual test process.  */
+static void
+enospc_failure_1 (void *closure)
+{
+#ifdef CLONE_NEWNS
+  support_become_root ();
+
+  /* Make sure that we do not alter the file system mounts of the
+     parents.  */
+  if (! support_enter_mount_namespace ())
+    {
+      printf ("warning: ENOSPC test skipped\n");
+      return;
+    }
+
+  char *mountpoint = closure;
+  if (mount ("none", mountpoint, "tmpfs", MS_NODEV | MS_NOEXEC,
+             "size=500k") != 0)
+    {
+      printf ("warning: could not mount tmpfs at %s: %m\n", mountpoint);
+      return;
+    }
+
+  /* The source file must reside on the same file system.  */
+  char *intmpfsfile = xasprintf ("%s/%s", mountpoint, "in");
+  int intmpfsfd = xopen (intmpfsfile, O_RDWR | O_CREAT | O_LARGEFILE, 0600);
+  xwrite (intmpfsfd, random_data, sizeof (random_data));
+  xlseek (intmpfsfd, 1, SEEK_SET);
+  inoff = 1;
+
+  char *outtmpfsfile = xasprintf ("%s/%s", mountpoint, "out");
+  int outtmpfsfd = xopen (outtmpfsfile, O_RDWR | O_CREAT | O_LARGEFILE, 0600);
+
+  /* Fill the file with data until ENOSPC is reached.  */
+  while (true)
+    {
+      ssize_t ret = write (outtmpfsfd, random_data, sizeof (random_data));
+      if (ret < 0 && errno != ENOSPC)
+        FAIL_EXIT1 ("write to %s: %m", outtmpfsfile);
+      if (ret < sizeof (random_data))
+        break;
+    }
+  TEST_COMPARE (write (outtmpfsfd, "", 1), -1);
+  TEST_COMPARE (errno, ENOSPC);
+  off64_t maxsize = xlseek (outtmpfsfd, 0, SEEK_CUR);
+  TEST_VERIFY_EXIT (maxsize > sizeof (random_data));
+
+  /* Constructed the expected file contents.  */
+  char *expected = xmalloc (maxsize);
+  TEST_COMPARE (pread64 (outtmpfsfd, expected, maxsize, 0), maxsize);
+  /* Go back a little, so some bytes can be written.  */
+  enum { offset = 20000 };
+  TEST_VERIFY_EXIT (offset < maxsize);
+  TEST_VERIFY_EXIT (offset < sizeof (random_data));
+  memcpy (expected + maxsize - offset, random_data + 1, offset);
+
+  if (do_outoff)
+    {
+      outoff = maxsize - offset;
+      xlseek (outtmpfsfd, 2, SEEK_SET);
+    }
+  else
+    xlseek (outtmpfsfd, -offset, SEEK_CUR);
+
+  /* First call is expected to succeed because we made room for some
+     bytes.  */
+  TEST_COMPARE (copy_file_range (intmpfsfd, pinoff, outtmpfsfd, poutoff,
+                                 maximum_size, 0), offset);
+  if (do_inoff)
+    {
+      TEST_COMPARE (inoff, 1 + offset);
+      TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1);
+    }
+  else
+      TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1 + offset);
+  if (do_outoff)
+    {
+      TEST_COMPARE (outoff, maxsize);
+      TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), 2);
+    }
+  else
+    TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), maxsize);
+  struct stat64 st;
+  xfstat (outtmpfsfd, &st);
+  TEST_COMPARE (st.st_size, maxsize);
+  char *actual = xmalloc (st.st_size);
+  TEST_COMPARE (pread64 (outtmpfsfd, actual, st.st_size, 0), st.st_size);
+  TEST_VERIFY (memcmp (expected, actual, maxsize) == 0);
+
+  /* Second call should fail with ENOSPC.  */
+  TEST_COMPARE (copy_file_range (intmpfsfd, pinoff, outtmpfsfd, poutoff,
+                                 maximum_size, 0), -1);
+  TEST_COMPARE (errno, ENOSPC);
+
+  /* Offsets should be unchanged.  */
+  if (do_inoff)
+    {
+      TEST_COMPARE (inoff, 1 + offset);
+      TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1);
+    }
+  else
+    TEST_COMPARE (xlseek (intmpfsfd, 0, SEEK_CUR), 1 + offset);
+  if (do_outoff)
+    {
+      TEST_COMPARE (outoff, maxsize);
+      TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), 2);
+    }
+  else
+    TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_CUR), maxsize);
+  TEST_COMPARE (xlseek (outtmpfsfd, 0, SEEK_END), maxsize);
+  TEST_COMPARE (pread64 (outtmpfsfd, actual, maxsize, 0), maxsize);
+  TEST_VERIFY (memcmp (expected, actual, maxsize) == 0);
+
+  free (actual);
+  free (expected);
+
+  xclose (intmpfsfd);
+  xclose (outtmpfsfd);
+  free (intmpfsfile);
+  free (outtmpfsfile);
+
+#else /* !CLONE_NEWNS */
+  puts ("warning: ENOSPC test skipped (no mount namespaces)");
+#endif
+}
+
+/* Call enospc_failure_1 in a subprocess.  */
+static void
+enospc_failure (void)
+{
+  char *mountpoint
+    = support_create_temp_directory ("tst-copy_file_range-enospc-");
+  support_isolate_in_subprocess (enospc_failure_1, mountpoint);
+  free (mountpoint);
+}
+
+/* The target file descriptor must have O_APPEND enabled.  */
+static void
+oappend_failure (void)
+{
+  /* Add data, to make sure we do not fail because there is
+     insufficient input data.  */
+  xwrite (infd, random_data, current_size);
+  xlseek (infd, 0, SEEK_SET);
+
+  xclose (outfd);
+  outfd = xopen (outfile, O_RDWR | O_APPEND, 0);
+  TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
+                                 current_size, 0), -1);
+  TEST_COMPARE (errno, EBADF);
+}
+
+/* Test that a short input file results in a shortened copy.  */
+static void
+short_copy (void)
+{
+  if (current_size == 0)
+    /* Nothing to shorten.  */
+    return;
+
+  /* Two subtests, one with offset 0 and current_size - 1 bytes, and
+     another one with current_size bytes, but offset 1.  */
+  for (int shift = 0; shift < 2; ++shift)
+    {
+      if (test_verbose > 0)
+        printf ("info:   shift=%d\n", shift);
+      xftruncate (infd, 0);
+      xlseek (infd, 0, SEEK_SET);
+      xwrite (infd, random_data, current_size - !shift);
+
+      if (do_inoff)
+        {
+          inoff = shift;
+          xlseek (infd, 2, SEEK_SET);
+        }
+      else
+        {
+          inoff = 3;
+          xlseek (infd, shift, SEEK_SET);
+        }
+      ftruncate (outfd, 0);
+      xlseek (outfd, 0, SEEK_SET);
+      outoff = 0;
+
+      /* First call copies current_size - 1 bytes.  */
+      TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
+                                     current_size, 0), current_size - 1);
+      char *buffer = xmalloc (current_size);
+      TEST_COMPARE (pread64 (outfd, buffer, current_size, 0),
+                    current_size - 1);
+      TEST_VERIFY (memcmp (buffer, random_data + shift, current_size - 1)
+                   == 0);
+      free (buffer);
+
+      if (do_inoff)
+        {
+          TEST_COMPARE (inoff, current_size - 1 + shift);
+          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 2);
+        }
+      else
+        TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), current_size - 1 + shift);
+      if (do_outoff)
+        {
+          TEST_COMPARE (outoff, current_size - 1);
+          TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 0);
+        }
+      else
+        TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), current_size - 1);
+
+      /* First call copies zero bytes.  */
+      TEST_COMPARE (copy_file_range (infd, pinoff, outfd, poutoff,
+                                     current_size, 0), 0);
+      /* And the offsets are unchanged.  */
+      if (do_inoff)
+        {
+          TEST_COMPARE (inoff, current_size - 1 + shift);
+          TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), 2);
+        }
+      else
+        TEST_COMPARE (xlseek (infd, 0, SEEK_CUR), current_size - 1 + shift);
+      if (do_outoff)
+        {
+          TEST_COMPARE (outoff, current_size - 1);
+          TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), 0);
+        }
+      else
+        TEST_COMPARE (xlseek (outfd, 0, SEEK_CUR), current_size - 1);
+    }
+}
+
+/* A named test function.  */
+struct test_case
+{
+  const char *name;
+  void (*func) (void);
+  bool sizes; /* If true, call the test with different current_size values.  */
+};
+
+/* The available test cases.  */
+static struct test_case tests[] =
+  {
+    { "simple_file_copy", simple_file_copy, .sizes = true },
+    { "pipe_as_source", pipe_as_source, },
+    { "pipe_as_destination", pipe_as_destination, },
+    { "delayed_write_failure", delayed_write_failure, .sizes = true },
+    { "cross_device_failure", cross_device_failure, .sizes = true },
+    { "enospc_failure", enospc_failure, },
+    { "oappend_failure", oappend_failure, .sizes = true },
+    { "short_copy", short_copy, .sizes = true },
+  };
+
+static int
+do_test (void)
+{
+  for (unsigned char *p = random_data; p < array_end (random_data); ++p)
+    *p = rand () >> 24;
+
+  infd = create_temp_file ("tst-copy_file_range-in-", &infile);
+  xclose (create_temp_file ("tst-copy_file_range-out-", &outfile));
+
+  /* Try to find a different directory from the default input/output
+     file.  */
+  {
+    struct stat64 instat;
+    xfstat (infd, &instat);
+    static const char *const candidates[] =
+      { NULL, "/var/tmp", "/dev/shm" };
+    for (const char *const *c = candidates; c < array_end (candidates); ++c)
+      {
+        const char *path = *c;
+        char *to_free = NULL;
+        if (path == NULL)
+          {
+            to_free = xreadlink ("/proc/self/exe");
+            path = dirname (to_free);
+          }
+
+        struct stat64 cstat;
+        xstat (path, &cstat);
+        if (cstat.st_dev == instat.st_dev)
+          {
+            free (to_free);
+            continue;
+          }
+
+        printf ("info: using alternate temporary files directory: %s\n", path);
+        xdevfile = xasprintf ("%s/tst-copy_file_range-xdev-XXXXXX", path);
+        free (to_free);
+        break;
+      }
+    if (xdevfile != NULL)
+      {
+        int xdevfd = mkstemp (xdevfile);
+        if (xdevfd < 0)
+          FAIL_EXIT1 ("mkstemp (\"%s\"): %m", xdevfile);
+        struct stat64 xdevst;
+        xfstat (xdevfd, &xdevst);
+        TEST_VERIFY (xdevst.st_dev != instat.st_dev);
+        add_temp_file (xdevfile);
+        xclose (xdevfd);
+      }
+    else
+      puts ("warning: no alternate directory on different file system found");
+  }
+  xclose (infd);
+
+  for (do_inoff = 0; do_inoff < 2; ++do_inoff)
+    for (do_outoff = 0; do_outoff < 2; ++do_outoff)
+      for (struct test_case *test = tests; test < array_end (tests); ++test)
+        for (const int *size = typical_sizes;
+             size < array_end (typical_sizes); ++size)
+          {
+            current_size = *size;
+            if (test_verbose > 0)
+              printf ("info: %s do_inoff=%d do_outoff=%d current_size=%d\n",
+                      test->name, do_inoff, do_outoff, current_size);
+
+            inoff = 0;
+            if (do_inoff)
+              pinoff = &inoff;
+            else
+              pinoff = NULL;
+            outoff = 0;
+            if (do_outoff)
+              poutoff = &outoff;
+            else
+              poutoff = NULL;
+
+            infd = xopen (infile, O_RDWR | O_LARGEFILE, 0);
+            xftruncate (infd, 0);
+            outfd = xopen (outfile, O_RDWR | O_LARGEFILE, 0);
+            xftruncate (outfd, 0);
+
+            test->func ();
+
+            xclose (infd);
+            xclose (outfd);
+
+            if (!test->sizes)
+              /* Skip the other sizes unless they have been
+                 requested.  */
+              break;
+          }
+
+  free (infile);
+  free (outfile);
+  free (xdevfile);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/manual/llio.texi b/manual/llio.texi
index 8b2f599c79..37593f18d4 100644
--- a/manual/llio.texi
+++ b/manual/llio.texi
@@ -41,6 +41,7 @@  directly.)
 * Stream/Descriptor Precautions::       Precautions needed if you use both
                                          descriptors and streams.
 * Scatter-Gather::                      Fast I/O to discontinuous buffers.
+* Copying File Data::                   Copying data between files.
 * Memory-mapped I/O::                   Using files like memory.
 * Waiting for I/O::                     How to check for input or output
 					 on multiple file descriptors.
@@ -1353,6 +1354,80 @@  When the source file is compiled using @code{_FILE_OFFSET_BITS == 64} on a
 @code{pwritev2} and so transparently replaces the 32 bit interface.
 @end deftypefun
 
+@node Copying File Data
+@section Copying data between two files
+@cindex copying files
+@cindex file copy
+
+A special function is provided to copy data between two files on the
+same file system.  The system can optimize such copy operations.  This
+is particularly important on network file systems, where the data would
+otherwise have to be transferred twice over the network.
+
+Note that this function only copies file data, but not metadata such as
+file permissions or extended attributes.
+
+@deftypefun ssize_t copy_file_range (int @var{inputfd}, off64_t *@var{inputpos}, int @var{outputfd}, off64_t *@var{outputpos}, ssize_t @var{length}, unsigned int @var{flags})
+@standards{GNU, unistd.h}
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
+
+This function copies up to @var{length} bytes from the file descriptor
+@var{inputfd} to the file descriptor @var{outputfd}.
+
+The function can operate on both the current file position (like
+@code{read} and @code{write}) and an explicit offset (like @code{pread}
+and @code{pwrite}).  If the @var{inputpos} pointer is null, the file
+position of @var{inputfd} is used as the starting point of the copy
+operation, and the file position is advanced during it.  If
+@var{inputpos} is not null, then @code{*@var{inputpos}} is used as the
+starting point of the copy operation, and @code{*@var{inputpos}} is
+incremented by the number of copied bytes, but the file position remains
+unchanged.  Similar rules apply to @var{outputfd} and @var{outputpos}
+for the output file position.
+
+The @var{flags} argument is currently reserved and must be zero.
+
+The @code{copy_file_range} function returns the number of bytes copied.
+This can be less than the specified @var{length} in case the input file
+contains fewer remaining bytes than @var{length}, or if a read or write
+failure occurs.  The return value is zero if the end of the input file
+is encountered immediately.
+
+If no bytes can be copied, to report an error, @code{copy_file_range}
+returns the value @math{-1} and sets @code{errno}.  The following
+@code{errno} error conditions are specific to this function:
+
+@table @code
+@item EISDIR
+At least one of the descriptors @var{inputfd} or @var{outputfd} refers
+to a directory.
+
+@item EINVAL
+At least one of the descriptors @var{inputfd} or @var{outputfd} refers
+to a non-regular, non-directory file (such as a socket or a FIFO).
+
+The @var{flags} argument is not zero.
+
+@item EBADF
+The argument @var{inputfd} is not a valid file descriptor open for
+reading.
+
+The argument @var{outputfd} is not a valid file descriptor open for
+writing, or @var{outputfd} has been opened with @code{O_APPEND}.
+
+@item EXDEV
+The input and output files reside on different file systems.
+@end table
+
+In addition, @code{copy_file_range} can fail with the error codes
+which are used by @code{read}, @code{pread}, @code{write}, and
+@code{pwrite}.
+
+The @code{copy_file_range} function is a cancellation point.  In case of
+cancellation, the input location (the file position or the value at
+@code{*@var{inputpos}}) is indeterminate.
+@end deftypefun
+
 @node Memory-mapped I/O
 @section Memory-mapped I/O
 
diff --git a/posix/unistd.h b/posix/unistd.h
index 32b0f4898f..65317c79fd 100644
--- a/posix/unistd.h
+++ b/posix/unistd.h
@@ -1105,7 +1105,12 @@  extern int lockf64 (int __fd, int __cmd, __off64_t __len) __wur;
        do __result = (long int) (expression);				      \
        while (__result == -1L && errno == EINTR);			      \
        __result; }))
-#endif
+
+/* Copy LENGTH bytes from INFD to OUTFD.  */
+ssize_t copy_file_range (int __infd, __off64_t *__pinoff,
+			 int __outfd, __off64_t *__poutoff,
+			 size_t __length, unsigned int __flags);
+#endif /* __USE_GNU */
 
 #if defined __USE_POSIX199309 || defined __USE_UNIX98
 /* Synchronize at least the data part of a file with the underlying
diff --git a/support/Makefile b/support/Makefile
index bb81825fc2..7aa8dd0bdd 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -36,6 +36,7 @@  libsupport-routines = \
   oom_error \
   resolv_test \
   set_fortify_handler \
+  support-xfstat \
   support-xstat \
   support_become_root \
   support_can_chroot \
@@ -73,8 +74,10 @@  libsupport-routines = \
   xfclose \
   xfopen \
   xfork \
+  xftruncate \
   xgetsockname \
   xlisten \
+  xlseek \
   xmalloc \
   xmemstream \
   xmkdir \
diff --git a/support/support-xfstat.c b/support/support-xfstat.c
new file mode 100644
index 0000000000..4c8ee9142b
--- /dev/null
+++ b/support/support-xfstat.c
@@ -0,0 +1,28 @@ 
+/* fstat64 with error checking.
+   Copyright (C) 2017 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 <support/check.h>
+#include <support/xunistd.h>
+#include <sys/stat.h>
+
+void
+xfstat (int fd, struct stat64 *result)
+{
+  if (fstat64 (fd, result) != 0)
+    FAIL_EXIT1 ("fstat64 (%d): %m", fd);
+}
diff --git a/support/xftruncate.c b/support/xftruncate.c
new file mode 100644
index 0000000000..9c4e9e3050
--- /dev/null
+++ b/support/xftruncate.c
@@ -0,0 +1,27 @@ 
+/* ftruncate with error checking.
+   Copyright (C) 2017 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 <support/check.h>
+#include <support/xunistd.h>
+
+void
+xftruncate (int fd, long long length)
+{
+  if (ftruncate64 (fd, length) != 0)
+    FAIL_EXIT1 ("ftruncate64 (%d, %lld): %m", fd, length);
+}
diff --git a/support/xlseek.c b/support/xlseek.c
new file mode 100644
index 0000000000..0a75a9f2e6
--- /dev/null
+++ b/support/xlseek.c
@@ -0,0 +1,29 @@ 
+/* lseek with error checking.
+   Copyright (C) 2017 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 <support/check.h>
+#include <support/xunistd.h>
+
+long long
+xlseek (int fd, long long offset, int whence)
+{
+  long long result = lseek64 (fd, offset, whence);
+  if (result < 0)
+    FAIL_EXIT1 ("lseek64 (%d, %lld, %d): %m", fd, offset, whence);
+  return result;
+}
diff --git a/support/xunistd.h b/support/xunistd.h
index 05c2626a7b..548f234788 100644
--- a/support/xunistd.h
+++ b/support/xunistd.h
@@ -36,9 +36,12 @@  void xpipe (int[2]);
 void xdup2 (int, int);
 int xopen (const char *path, int flags, mode_t);
 void xstat (const char *path, struct stat64 *);
+void xfstat (int fd, struct stat64 *);
 void xmkdir (const char *path, mode_t);
 void xchroot (const char *path);
 void xunlink (const char *path);
+long long xlseek (int fd, long long offset, int whence);
+void xftruncate (int fd, long long length);
 
 /* Read the link at PATH.  The caller should free the returned string
    with free.  */
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index 3448d62cee..4ffcd7fcfd 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2104,6 +2104,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index d064f5445e..32777457d9 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2015,6 +2015,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
index a5ce7964d0..a0fc14b0fc 100644
--- a/sysdeps/unix/sysv/linux/arm/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
@@ -105,6 +105,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/copy_file_range.c b/sysdeps/unix/sysv/linux/copy_file_range.c
new file mode 100644
index 0000000000..1ec5f9d8d8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/copy_file_range.c
@@ -0,0 +1,46 @@ 
+/* Linux implementation of copy_file_range.
+   Copyright (C) 2017 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 <sysdep-cancel.h>
+#include <unistd.h>
+
+/* Include the fallback implementation.  */
+#ifndef __ASSUME_COPY_FILE_RANGE
+#define COPY_FILE_RANGE_DECL static
+#define COPY_FILE_RANGE copy_file_range_compat
+#include <io/copy_file_range-compat.c>
+#endif
+
+ssize_t
+copy_file_range (int infd, __off64_t *pinoff,
+                 int outfd, __off64_t *poutoff,
+                 size_t length, unsigned int flags)
+{
+#ifdef __NR_copy_file_range
+  ssize_t ret = SYSCALL_CANCEL (copy_file_range, infd, pinoff, outfd, poutoff,
+                                length, flags);
+# ifndef __ASSUME_COPY_FILE_RANGE
+  if (ret == -1 && errno == ENOSYS)
+    ret = copy_file_range_compat (infd, pinoff, outfd, poutoff, length, flags);
+# endif
+  return ret;
+#else  /* !__NR_copy_file_range */
+  return copy_file_range_compat (infd, pinoff, outfd, poutoff, length, flags);
+#endif
+}
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 69ddf15361..12e2b0b206 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -1869,6 +1869,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index a140edd4a3..52964476d5 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2034,6 +2034,7 @@  GLIBC_2.26 strtof128_l F
 GLIBC_2.26 wcstof128 F
 GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index 178c0a45ec..58c1b0add8 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -1898,6 +1898,7 @@  GLIBC_2.26 strtof128_l F
 GLIBC_2.26 wcstof128 F
 GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 59b613377f..b9864790c7 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -111,3 +111,7 @@ 
 #if __LINUX_KERNEL_VERSION >= 0x040400
 # define __ASSUME_MLOCK2 1
 #endif
+
+#if __LINUX_KERNEL_VERSION >= 0x040500
+# define __ASSUME_COPY_FILE_RANGE 1
+#endif
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index 01d10d907c..915ffbb7e8 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -106,6 +106,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index 3ad08c20bf..d2e0ebfebe 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -1983,6 +1983,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
index 6bd7be1929..c58669ba2e 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
@@ -2104,6 +2104,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 9b1e890eda..dd120b02c9 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -1958,6 +1958,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index 3eb5b66f8b..2aeb46917c 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -1956,6 +1956,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index 543a725114..b24b4134ca 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -1954,6 +1954,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index a9198a3936..6e4f827b69 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -1949,6 +1949,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index afacf1ff2d..ff4a3b9515 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2145,6 +2145,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index 48af097b6a..71e49a13d8 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_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index e30535dac9..2e8ca8bd93 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -1992,6 +1992,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
index f522700890..f0c7a65b39 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
@@ -2199,6 +2199,7 @@  GLIBC_2.26 strtof128_l F
 GLIBC_2.26 wcstof128 F
 GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
index d3092afd25..95db2aad5c 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
@@ -106,6 +106,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index 752176108e..c77fa8e07f 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -1987,6 +1987,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index b6d4c73635..c48fdcb978 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -1888,6 +1888,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
index 1ee21fe8e8..7c77f15c65 100644
--- a/sysdeps/unix/sysv/linux/sh/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
@@ -1873,6 +1873,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index e652191c60..c23a2d9ca7 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -1980,6 +1980,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index 37cf8713a5..1c035bceec 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -1917,6 +1917,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
index 57427eb3ee..d843815aa6 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
@@ -2111,6 +2111,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
index 321f65c600..9d8b6f7ed2 100644
--- a/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
@@ -2111,6 +2111,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
index 57427eb3ee..d843815aa6 100644
--- a/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
+++ b/sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
@@ -2111,6 +2111,7 @@  GLIBC_2.26 pwritev2 F
 GLIBC_2.26 pwritev64v2 F
 GLIBC_2.26 reallocarray F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index f26c8b99d5..7365702953 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -1875,6 +1875,7 @@  GLIBC_2.26 strtof128_l F
 GLIBC_2.26 wcstof128 F
 GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index 2a6057154b..ebc228d4e7 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2118,6 +2118,7 @@  GLIBC_2.26 strtof128_l F
 GLIBC_2.26 wcstof128 F
 GLIBC_2.26 wcstof128_l F
 GLIBC_2.27 GLIBC_2.27 A
+GLIBC_2.27 copy_file_range F
 GLIBC_2.27 glob F
 GLIBC_2.27 glob64 F
 GLIBC_2.27 memfd_create F