[gvfs] channel: Unqueue cancelled requests

[Alexander Larsson <alexl src gnome org>]

commit f25b407fdc1ea5624ebe8b8b0e026615f1f14243
Author: Alexander Larsson <alexl redhat com>
Date:   Thu Apr 4 19:08:02 2013 +0200

    channel: Unqueue cancelled requests
    
    We put a channel request on the output buffer and start writing, but
    if the write is cancelled on the first call (i.e. no partial writes)
    we abort immediately without ever writing the request.
    
    However, if we do this we also need to unqueue the request from the output
    buffer, as otherwise this will be sent with the next operation. This
    can be problematic for seeks as the seek generation is then not in sync.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=675181

 client/gdaemonfileinputstream.c  |   18 ++++++++++++++++++
 client/gdaemonfileoutputstream.c |   17 +++++++++++++++++
 daemon/gvfschannel.c             |   16 +++++++---------
 3 files changed, 42 insertions(+), 9 deletions(-)
---
diff --git a/client/gdaemonfileinputstream.c b/client/gdaemonfileinputstream.c
index bfe02bd..f73c681 100644
--- a/client/gdaemonfileinputstream.c
+++ b/client/gdaemonfileinputstream.c
@@ -394,6 +394,16 @@ error_is_cancel (GError *error)
 }
 
 static void
+unappend_request (GDaemonFileInputStream *stream)
+{
+  g_assert (stream->output_buffer->len >= G_VFS_DAEMON_SOCKET_PROTOCOL_REQUEST_SIZE);
+
+  stream->seq_nr--;
+  g_string_truncate (stream->output_buffer,
+                    stream->output_buffer->len - G_VFS_DAEMON_SOCKET_PROTOCOL_REQUEST_SIZE);
+}
+
+static void
 append_request (GDaemonFileInputStream *stream, guint32 command,
                guint32 arg1, guint32 arg2, guint32 data_len,
                guint32 *seq_nr)
@@ -623,6 +633,8 @@ iterate_read_state_machine (GDaemonFileInputStream *file, IOOperationData *io_op
        case READ_STATE_WROTE_COMMAND:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->ret_val = -1;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
@@ -894,6 +906,8 @@ iterate_close_state_machine (GDaemonFileInputStream *file, IOOperationData *io_o
        case CLOSE_STATE_WROTE_REQUEST:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->ret_val = FALSE;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
@@ -1142,6 +1156,8 @@ iterate_seek_state_machine (GDaemonFileInputStream *file, IOOperationData *io_op
        case SEEK_STATE_WROTE_REQUEST:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->ret_val = -1;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
@@ -1384,6 +1400,8 @@ iterate_query_state_machine (GDaemonFileInputStream *file,
        case QUERY_STATE_WROTE_REQUEST:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->info = NULL;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
diff --git a/client/gdaemonfileoutputstream.c b/client/gdaemonfileoutputstream.c
index 4516c97..70535b1 100644
--- a/client/gdaemonfileoutputstream.c
+++ b/client/gdaemonfileoutputstream.c
@@ -316,6 +316,15 @@ error_is_cancel (GError *error)
 }
 
 static void
+unappend_request (GDaemonFileOutputStream *stream)
+{
+  g_assert (stream->output_buffer->len >= G_VFS_DAEMON_SOCKET_PROTOCOL_REQUEST_SIZE);
+  stream->seq_nr--;
+  g_string_truncate (stream->output_buffer,
+                    stream->output_buffer->len - G_VFS_DAEMON_SOCKET_PROTOCOL_REQUEST_SIZE);
+}
+
+static void
 append_request (GDaemonFileOutputStream *stream, guint32 command,
                guint32 arg1, guint32 arg2, guint32 data_len, guint32 *seq_nr)
 {
@@ -499,6 +508,8 @@ iterate_write_state_machine (GDaemonFileOutputStream *file, IOOperationData *io_
        case WRITE_STATE_WROTE_COMMAND:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->ret_val = -1;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
@@ -674,6 +685,8 @@ iterate_close_state_machine (GDaemonFileOutputStream *file, IOOperationData *io_
        case CLOSE_STATE_WROTE_REQUEST:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->ret_val = FALSE;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
@@ -866,6 +879,8 @@ iterate_seek_state_machine (GDaemonFileOutputStream *file, IOOperationData *io_o
        case SEEK_STATE_WROTE_REQUEST:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->ret_val = -1;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
@@ -1045,6 +1060,8 @@ iterate_query_state_machine (GDaemonFileOutputStream *file,
        case QUERY_STATE_WROTE_REQUEST:
          if (io_op->io_cancelled)
            {
+             if (!op->sent_cancel)
+               unappend_request (file);
              op->info = NULL;
              g_set_error_literal (&op->ret_error,
                                   G_IO_ERROR,
diff --git a/daemon/gvfschannel.c b/daemon/gvfschannel.c
index ec87cb9..994b5ea 100644
--- a/daemon/gvfschannel.c
+++ b/daemon/gvfschannel.c
@@ -321,21 +321,19 @@ start_queued_request (GVfsChannel *channel)
                                   req->arg1, req->arg2,
                                   req->data, req->data_len,
                                   &error);
-      if (job == NULL)
-       {
-         job = g_vfs_job_error_new (channel, error);
-         g_error_free (error);
-       }
-
 
       if (job != NULL && req->cancelled)
        {
          /* Ignore the job, although we need to create it to rely
             on handle_request side effects like seek generations, etc */
          g_object_unref (job);
-         error =
-           g_error_new_literal (G_IO_ERROR, G_IO_ERROR_CANCELLED,
-                                _("Operation was cancelled"));
+         job = NULL;
+         error =  g_error_new_literal (G_IO_ERROR, G_IO_ERROR_CANCELLED,
+                                       _("Operation was cancelled"));
+       }
+
+      if (job == NULL)
+       {
          job = g_vfs_job_error_new (channel, error);
          g_error_free (error);
        }