copy_file_range: New function to copy file data

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

44 files changed, 1340 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 55295b1368..14950fe373 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,24 @@
+2017-12-22  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.
+
 2017-12-21  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	* scripts/build-many-glibcs.py (Context.add_all_configs): Add
diff --git a/NEWS b/NEWS
index d60b31575d..2a1a4bfd85 100644
--- a/NEWS
+++ b/NEWS
@@ -61,6 +61,8 @@ Major new features:
   declares the functions pkey_alloc, pkey_free, pkey_mprotect, pkey_set,
   pkey_get.
 
+* The copy_file_range function was added.
+
 * Optimized memcpy, mempcpy, memmove, and memset for sparc M7.
 
 * The ldconfig utility now processes `include' directives using the C/POSIX
diff --git a/io/Makefile b/io/Makefile
index c72519541f..85eb927d4c 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..5c1b7b3258
--- /dev/null
+++ b/io/copy_file_range-compat.c
@@ -0,0 +1,160 @@
+/* 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 != NULL)
+        *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 + written > 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..d8f4e8ac04
--- /dev/null
+++ b/io/tst-copy_file_range.c
@@ -0,0 +1,833 @@
+/* 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>