From 47d7532e093db8a5068a40c587915121ffaaad18 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Wed, 13 Mar 2013 11:42:22 -0700
Subject: File synchronization fixes.

* admin/CPP-DEFINES (BSD_SYSTEM, HAVE_FSYNC): Remove.
* admin/merge-gnulib (GNULIB_MODULES): Add fsync, fdatasync.
* configure.ac (BSD_SYSTEM, BSD_SYSTEM_AHB): Remove; no longer needed.
(fsync): Remove check; now done by gnulib.
* lib/fdatasync.c, lib/fsync.c, m4/fdatasync.m4, m4/fsync.m4:
New files, from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib-src/Makefile.in (LIB_FDATASYNC): New macro.
(emacsclient${EXEEXT}): Use it.
* lib-src/emacsclient.c (main): Use fdatasync, not fsync, since we don't
care about metadata.  Keep trying if interrupted.
* lib-src/movemail.c (main, popmail): Don't worry about BSD_SYSTEM, since
fsync is available everywhere (or there is a substitute).  Don't
report an error if fsync returns EINVAL.
* nt/inc/ms-w32.h (fdatasync): New macro, suggested by Eli Zaretskii.
* src/Makefile.in (LIB_FDATASYNC): New macro.
(LIBES): Use it.
* src/conf_post.h (BSD_SYSTEM, BSD_SYSTEM_AHB): Remove; no longer needed.
* src/fileio.c (Fwrite_region, write_region_inhibit_fsync):
Don't worry about HAVE_FSYNC, since a substitute fsync is
available if the system lacks one.
(Fwrite_regin): Retry fsync if interrupted.

Fixes: debbugs:13944
---
 lib/fsync.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 lib/fsync.c

(limited to 'lib/fsync.c')

diff --git a/lib/fsync.c b/lib/fsync.c
new file mode 100644
index 00000000000..8a1a975049e
--- /dev/null
+++ b/lib/fsync.c
@@ -0,0 +1,83 @@
+/* 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) 2008-2013 Free Software Foundation, Inc.
+
+   This library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public
+   License as published by the Free Software Foundation; either
+   version 3 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
+   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__
+
+/* FlushFileBuffers */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+
+# include <errno.h>
+
+/* Get _get_osfhandle.  */
+# include "msvc-nothrow.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)
+        {
+        case ERROR_ACCESS_DENIED:
+          /* For a read-only handle, fsync should succeed, even though we have
+             no way to sync the access-time changes.  */
+          return 0;
+
+          /* 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 */
-- 
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