test-container: Use xcopy_file_range for cross-device copy [BZ #23597]

copy_file_range can't be used to copy a file from glibc source directory
to glibc build directory since they may be on different filesystems.
This patch adds xcopy_file_range for cross-device copy.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	[BZ #23597]
	* support/Makefile (libsupport-routines): Add
	support_copy_file_range and xcopy_file_range.
	* support/support.h: Include <sys/types.h>.
	(support_copy_file_range): New prototype.
	* support/support_copy_file_range.c: New file.  Copied and
	modified from io/copy_file_range-compat.c.
	* support/test-container.c (copy_one_file): Call xcopy_file_rang
	instead of copy_file_range.
	* support/xcopy_file_range.c: New file.
	* support/xunistd.h (xcopy_file_range): New prototype.

1 files changed, 143 insertions, 0 deletions

diff --git a/support/support_copy_file_range.c b/support/support_copy_file_range.c
new file mode 100644
index 0000000000..9a1e39773e
--- /dev/null
+++ b/support/support_copy_file_range.c
@@ -0,0 +1,143 @@
+/* Simplified copy_file_range with cross-device copy.
+   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 <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <support/support.h>
+
+ssize_t
+support_copy_file_range (int infd, __off64_t *pinoff,
+			 int outfd, __off64_t *poutoff,
+			 size_t length, unsigned int flags)
+{
+  if (flags != 0)
+    {
+      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))
+    {
+      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.  */
+      errno = EINVAL;
+      return -1;
+    }
+
+  /* The output descriptor must not have O_APPEND set.  */
+  if (fcntl (outfd, F_GETFL) & O_APPEND)
+    {
+      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 = 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 = 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) lseek64 (infd, -overread, SEEK_CUR);
+		      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;
+}