fsync: new module

* lib/fsync.c: New file.
* m4/fsync.m4: New file.
* modules/fsync: New file.
* modules/fsync-tests: New file.
* tests/test-fsync.c: New file.
* modules/unistd: Substitute GNULIB_FSYNC and HAVE_FSYNC.
* m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Define and AC_SUBST
both GNULIB_FSYNC and HAVE_FSYNC.
* lib/unistd.in.h (@GNULIB_FSYNC@): Add a block for fsync.
* MODULES.html.sh (posix_functions): Add fsync.
* doc/posix-functions/fsync.texi: Update.

1 files changed, 78 insertions, 0 deletions

diff --git a/lib/fsync.c b/lib/fsync.c
new file mode 100644
index 0000000000..4a0fe0f94c
--- /dev/null
+++ b/lib/fsync.c
@@ -0,0 +1,78 @@
+/* Emulate fsync on platforms that lack it, primarily Windows and
+   cross-compilers like MinGW.
+
+   This is derived from sqlite3 sources.
+   http://www.sqlite.org/cvstrac/rlog?f=sqlite/src/os_win.c
+   http://www.sqlite.org/copyright.html
+
+   Written by Richard W.M. Jones <rjones.at.redhat.com>
+
+   Copyright (C) 2008 Free Software Foundation, Inc.
+
+   This 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.
+
+   This 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 General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+#include <unistd.h>
+
+#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
+
+/* _get_osfhandle */
+#include <io.h>
+
+/* FlushFileBuffers */
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+#include <errno.h>
+
+int
+fsync (int fd)
+{
+  HANDLE h = (HANDLE) _get_osfhandle (fd);
+  DWORD err;
+
+  if (h == INVALID_HANDLE_VALUE)
+    {
+      errno = EBADF;
+      return -1;
+    }
+
+  if (!FlushFileBuffers (h))
+    {
+      /* Translate some Windows errors into rough approximations of Unix
+       * errors.  MSDN is useless as usual - in this case it doesn't
+       * document the full range of errors.
+       */
+      err = GetLastError ();
+      switch (err)
+	{
+	  /* eg. Trying to fsync a tty. */
+	case ERROR_INVALID_HANDLE:
+	  errno = EINVAL;
+	  break;
+
+	default:
+	  errno = EIO;
+	}
+      return -1;
+    }
+
+  return 0;
+}
+
+#else /* !Windows */
+
+#error "This platform lacks fsync function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib."
+
+#endif /* !Windows */