[PATCH] fuse: Make created files visible immediately

[Stefan Hajnoczi <stefanha gmail com>]

This patch changes .vfs_create() to force file creation and then opens
the file again for replacement.  This ensures that the created file is
visible before its file handle is released.

Simple programs like touch(1) and cp(1) encounter ENOENT from creat(2)
on a WebDAV volume.  FUSE calls .vfs_create() followed by .vfs_getattr()
on the file as part of creat(2).  The .vfs_getattr() call after
.vfs_create() fails with ENOENT since the file handle is still open and
the file has not yet been created on the server side.  The WebDAV server
fails the PROPFIND request to the non-existent file.

Solve this problem by creating a file first and then reusing .vfs_open()
code to open the file writeable with O_TRUNC.

Signed-off-by: Stefan Hajnoczi <stefanha gmail com>
---
 client/gvfsfusedaemon.c |   69 +++++++++++++++++++++-------------------------
 1 files changed, 32 insertions(+), 37 deletions(-)

Thanks for your help on IRC alex and Company.

diff --git a/client/gvfsfusedaemon.c b/client/gvfsfusedaemon.c
index bc3090d..a331dfd 100644
--- a/client/gvfsfusedaemon.c
+++ b/client/gvfsfusedaemon.c
@@ -991,6 +991,34 @@ setup_output_stream (GFile *file, FileHandle *fh, int flags)
 }
 
 static gint
+open_common (const gchar *path, struct fuse_file_info *fi, GFile *file, int output_flags)
+{
+  gint        result;
+  FileHandle *fh = get_or_create_file_handle_for_path (path);
+
+  g_mutex_lock (fh->mutex);
+
+  /* File exists */
+
+  SET_FILE_HANDLE (fi, fh);
+
+  debug_print ("open_common: flags=%o\n", fi->flags);
+
+  /* Set up a stream here, so we can check for errors */
+  set_pid_for_file (file);
+
+  if (fi->flags & O_WRONLY || fi->flags & O_RDWR)
+    result = setup_output_stream (file, fh, fi->flags | output_flags);
+  else
+    result = setup_input_stream (file, fh);
+
+  g_mutex_unlock (fh->mutex);
+
+  /* The added reference to the file handle is released in vfs_release() */
+  return result;
+}
+
+static gint
 vfs_open (const gchar *path, struct fuse_file_info *fi)
 {
   GFile *file;
@@ -1013,27 +1041,7 @@ vfs_open (const gchar *path, struct fuse_file_info *fi)
 
           if (file_type == G_FILE_TYPE_REGULAR)
             {
-              FileHandle *fh = get_or_create_file_handle_for_path (path);
-
-              g_mutex_lock (fh->mutex);
-
-              /* File exists */
-
-              SET_FILE_HANDLE (fi, fh);
-
-              debug_print ("vfs_open: flags=%o\n", fi->flags);
-
-              /* Set up a stream here, so we can check for errors */
-              set_pid_for_file (file);
-
-              if (fi->flags & O_WRONLY || fi->flags & O_RDWR)
-                result = setup_output_stream (file, fh, fi->flags);
-              else
-                result = setup_input_stream (file, fh);
-
-              g_mutex_unlock (fh->mutex);
-
-              /* The added reference to the file handle is released in vfs_release() */
+              result = open_common (path, fi, file, 0);
             }
           else if (file_type == G_FILE_TYPE_DIRECTORY)
             {
@@ -1108,24 +1116,11 @@ vfs_create (const gchar *path, mode_t mode, struct fuse_file_info *fi)
             }
 
           file_output_stream = g_file_create (file, 0, NULL, &error);
-          set_pid_for_file (file);
           if (file_output_stream)
             {
-              FileHandle *fh = get_or_create_file_handle_for_path (path);
-
-              /* Success */
-
-              g_mutex_lock (fh->mutex);
-
-              SET_FILE_HANDLE (fi, fh);
-
-              file_handle_close_stream (fh);
-              fh->stream = file_output_stream;
-              fh->op = FILE_OP_WRITE;
-
-              g_mutex_unlock (fh->mutex);
-
-              /* The added reference to the file handle is released in vfs_release() */
+              g_output_stream_close (G_OUTPUT_STREAM (file_output_stream), NULL, NULL);
+              g_object_unref (file_output_stream);
+              result = open_common (path, fi, file, O_TRUNC);
             }
           else
             {
-- 
1.7.2.3