1 files changed, 122 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/posix/posix_fallocate.c b/REORG.TODO/sysdeps/posix/posix_fallocate.c
new file mode 100644
index 0000000000..f87f536bd9
--- /dev/null
+++ b/REORG.TODO/sysdeps/posix/posix_fallocate.c
@@ -0,0 +1,122 @@
+/* Copyright (C) 2000-2017 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 <fcntl.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+
+/* Reserve storage for the data of the file associated with FD.  This
+   emulation is far from perfect, but the kernel cannot do not much
+   better for network file systems, either.  */
+
+int
+posix_fallocate (int fd, __off_t offset, __off_t len)
+{
+  struct stat64 st;
+
+  if (offset < 0 || len < 0)
+    return EINVAL;
+
+  /* Perform overflow check.  The outer cast relies on a GCC
+     extension.  */
+  if ((__off_t) ((uint64_t) offset + (uint64_t) len) < 0)
+    return EFBIG;
+
+  /* pwrite below will not do the right thing in O_APPEND mode.  */
+  {
+    int flags = __fcntl (fd, F_GETFL, 0);
+    if (flags < 0 || (flags & O_APPEND) != 0)
+      return EBADF;
+  }
+
+  /* We have to make sure that this is really a regular file.  */
+  if (__fxstat64 (_STAT_VER, fd, &st) != 0)
+    return EBADF;
+  if (S_ISFIFO (st.st_mode))
+    return ESPIPE;
+  if (! S_ISREG (st.st_mode))
+    return ENODEV;
+
+  if (len == 0)
+    {
+      /* This is racy, but there is no good way to satisfy a
+	 zero-length allocation request.  */
+      if (st.st_size < offset)
+	{
+	  int ret = __ftruncate (fd, offset);
+
+	  if (ret != 0)
+	    ret = errno;
+	  return ret;
+	}
+      return 0;
+    }
+
+  /* Minimize data transfer for network file systems, by issuing
+     single-byte write requests spaced by the file system block size.
+     (Most local file systems have fallocate support, so this fallback
+     code is not used there.)  */
+
+  unsigned increment;
+  {
+    struct statfs64 f;
+
+    if (__fstatfs64 (fd, &f) != 0)
+      return errno;
+    if (f.f_bsize == 0)
+      increment = 512;
+    else if (f.f_bsize < 4096)
+      increment = f.f_bsize;
+    else
+      /* NFS does not propagate the block size of the underlying
+	 storage and may report a much larger value which would still
+	 leave holes after the loop below, so we cap the increment at
+	 4096.  */
+      increment = 4096;
+  }
+
+  /* Write a null byte to every block.  This is racy; we currently
+     lack a better option.  Compare-and-swap against a file mapping
+     might additional local races, but requires interposition of a
+     signal handler to catch SIGBUS.  */
+  for (offset += (len - 1) % increment; len > 0; offset += increment)
+    {
+      len -= increment;
+
+      if (offset < st.st_size)
+	{
+	  unsigned char c;
+	  ssize_t rsize = __pread (fd, &c, 1, offset);
+
+	  if (rsize < 0)
+	    return errno;
+	  /* If there is a non-zero byte, the block must have been
+	     allocated already.  */
+	  else if (rsize == 1 && c != 0)
+	    continue;
+	}
+
+      if (__pwrite (fd, "", 1, offset) != 1)
+	return errno;
+    }
+
+  return 0;
+}