Implement truncate support for output streams

Backends receive a TRUNCATE message which contains a size parameter.
Truncation is signaled with a TRUNCATED message (which contains no other
useful information).

In more detail:
Add a new dbus method, OpenForWriteFlags, which has a flags parameter to
implement can_seek and can_truncate.  These flags are used in
GDaemonFileOutputStream.  Compatability with old clients is maintained.
Implement the can_truncate and truncate_fn GDaemonFileOutputStream
methods.
Add two new message types to the daemon socket protocol:
    G_VFS_DAEMON_SOCKET_PROTOCOL_REQUEST_TRUNCATE
    G_VFS_DAEMON_SOCKET_PROTOCOL_REPLY_TRUNCATED
Add a new job type, GVfsJobTruncate.
Add two new methods to GVfsBackend which backend classes can implement:
truncate and try_truncate

https://bugzilla.gnome.org/show_bug.cgi?id=573837

1 files changed, 21 insertions, 1 deletions

diff --git a/daemon/gvfsjobopenforwrite.h b/daemon/gvfsjobopenforwrite.h
index 79854d23..141189f3 100644
--- a/daemon/gvfsjobopenforwrite.h
+++ b/daemon/gvfsjobopenforwrite.h
@@ -44,6 +44,11 @@ typedef enum {
   OPEN_FOR_WRITE_REPLACE = 2
 } GVfsJobOpenForWriteMode;
 
+typedef enum {
+  OPEN_FOR_WRITE_VERSION_ORIGINAL,
+  OPEN_FOR_WRITE_VERSION_WITH_FLAGS,
+} GVfsJobOpenForWriteVersion;
+
 struct _GVfsJobOpenForWrite
 {
   GVfsJobDBus parent_instance;
@@ -57,11 +62,14 @@ struct _GVfsJobOpenForWrite
   GVfsBackend *backend;
   GVfsBackendHandle backend_handle;
 
-  gboolean can_seek;
+  guint can_seek : 1;
+  guint can_truncate : 1;
   goffset initial_offset;
   GVfsWriteChannel *write_channel;
 
   GPid pid;
+
+  GVfsJobOpenForWriteVersion version;
 };
 
 struct _GVfsJobOpenForWriteClass
@@ -81,10 +89,22 @@ gboolean g_vfs_job_open_for_write_new_handle         (GVfsDBusMount         *obj
                                                       guint                  arg_flags,
                                                       guint                  arg_pid,
                                                       GVfsBackend           *backend);
+gboolean g_vfs_job_open_for_write_new_handle_with_flags (GVfsDBusMount         *object,
+                                                         GDBusMethodInvocation *invocation,
+                                                         GUnixFDList           *fd_list,
+                                                         const gchar           *arg_path_data,
+                                                         guint16                arg_mode,
+                                                         const gchar           *arg_etag,
+                                                         gboolean               arg_make_backup,
+                                                         guint                  arg_flags,
+                                                         guint                  arg_pid,
+                                                         GVfsBackend           *backend);
 void     g_vfs_job_open_for_write_set_handle         (GVfsJobOpenForWrite *job,
 						      GVfsBackendHandle    handle);
 void     g_vfs_job_open_for_write_set_can_seek       (GVfsJobOpenForWrite *job,
 						      gboolean             can_seek);
+void     g_vfs_job_open_for_write_set_can_truncate   (GVfsJobOpenForWrite *job,
+                                                      gboolean             can_truncate);
 void     g_vfs_job_open_for_write_set_initial_offset (GVfsJobOpenForWrite *job,
 						      goffset              initial_offset);
 GPid     g_vfs_job_open_for_write_get_pid            (GVfsJobOpenForWrite *job);