Re: [PATCH] fuse: Support ftruncate where requested size > current size

[Tomas Bzatek <tbzatek redhat com>]

Okay, could you please open a bugreport in bugzilla.gnome.org describing
your issue in detail? Let's deal with it separately.

Meanwhile, I've committed your padding code with minor changes.
-- 
Tomas Bzatek <tbzatek redhat com>


On Wed, 2012-05-23 at 12:42 -0500, whydoubt yahoo com wrote:
> No, not a strong reason.  In my case g_file_output_stream_query_info()
> was returning a not-supported error, but g_file_query_info() did work.
> I just haven't yet had time to go back to dig deeper.
> 
>   -- Jeff
> 
> 
> -----Original message-----
>         From: Tomas Bzatek <tbzatek redhat com>
>         To: gvfs-list gnome org
>         Cc: Jeff Smith <whydoubt yahoo com>
>         Sent: Mon, May 21, 2012 14:46:11 GMT+00:00
>         Subject: Re: [PATCH] fuse: Support ftruncate where requested
>         size > current size
>         
>         
>         Great addition, thanks for the patch, we're not giving much
>         love to the
>         fuse daemon these days.
>         
>         The second part (zero filling) looks good to me, I just did
>         not get the
>         first part - not using FGilexxputStream but GFile instead. Was
>         there a
>         strong reason? I mean, if the file is still open,
>         g_file_query_info()
>         may not give correct information until the file is closed.
>         This heavily
>         depends on the particular backend naturally.
>         
>         -- 
>         Tomas Bzatek 
>         
>         On Thu, 2012-05-17 at 23:58 -0500, Jeff Smith wrote:
>         > When ftruncate is called with a size greater than the
>         current size
>         > of the file, the expected behavior is that the file size
>         increases to
>         > the requested size, and the new space is zero-filled. SQLite
>         depends
>         > on this behavior when opening a database using 'write-ahead
>         log'
>         > journaling.
>         > 
>         > Signed-off-by: Jeff Smith 
>         > ---
>         > On iOS 5, the SQLite database MediaLibrary.sqlite uses
>         write-ahead
>         > logging. Without this patch, the only way to do anything
>         with the
>         > database (even to dump it) is to copy it from the
>         iPod/iPhone to a
>         > local filesystem, and then work with it.
>         > 
>         > client/gvfsfusedaemon.c | 26 ++++++++++++++++----------
>         > 1 file changed, 16 insertions(+), 10 deletions(-)
>         > 
>         > diff --git a/client/gvfsfusedaemon.c
>         b/client/gvfsfusedaemon.c
>         > index 8cf1c01..9f11678 100644
>         > --- a/client/gvfsfusedaemon.c
>         > +++ b/client/gvfsfusedaemon.c
>         > @@ -1814,6 +1814,7 @@ vfs_rmdir (const gchar *path)
>         > 
>         > static gboolean
>         > file_handle_get_size (FileHandle *fh,
>         > + GFile *file,
>         > goffset *size)
>         > {
>         > GFileInfo *info;
>         > @@ -1822,15 +1823,9 @@ file_handle_get_size (FileHandle *fh,
>         > if (fh->stream == NULL)
>         > return FALSE;
>         > 
>         > - info = NULL;
>         > - if (fh->op == FILE_OP_READ)
>         > - info = g_file_input_stream_query_info (fh->stream,
>         > - G_FILE_ATTRIBUTE_STANDARD_SIZE,
>         > - NULL, NULL);
>         > - else if (fh->op == FILE_OP_WRITE)
>         > - info = g_file_output_stream_query_info (fh->stream,
>         > - G_FILE_ATTRIBUTE_STANDARD_SIZE,
>         > - NULL, NULL);
>         > + info = g_file_query_info (file,
>         > + G_FILE_ATTRIBUTE_STANDARD_SIZE,
>         > + 0, NULL, NULL);
>         > 
>         > res = FALSE;
>         > if (info)
>         > @@ -1891,11 +1886,22 @@ vfs_ftruncate (const gchar *path,
>         off_t size, struct fuse_file_info *fi)
>         > fh->stream = NULL;
>         > }
>         > }
>         > - else if (file_handle_get_size (fh, &current_size) &&
>         > + else if (file_handle_get_size (fh, file, &current_size) &&
>         > current_size == size)
>         > {
>         > /* Don't have to do anything to succeed */
>         > }
>         > + else if ((current_size < size) &&
>         g_seekable_can_seek(G_SEEKABLE(fh->stream)))
>         > + {
>         > + /* If the truncated size is larger than the current size
>         > + * then we need to pad out the difference with 0's */
>         > + goffset orig_pos = g_seekable_tell
>         (G_SEEKABLE(fh->stream));
>         > + gsize buf_size = size - current_size;
>         > + gpointer buf = g_malloc0 (buf_size);
>         > + write_stream (fh, buf, buf_size, current_size);
>         > + g_free (buf);
>         > + g_seekable_seek (G_SEEKABLE(fh->stream), orig_pos,
>         G_SEEK_SET, NULL, NULL);
>         > + }
>         > else
>         > {
>         > result = -ENOTSUP;
>