[Spice-devel] [phodav PATCH 5/7 v3] spice-webdavd-windows: Automount shared folder

[Lukas Venhoda]

Try to connect to shared folder automatically on Windows.

On each loop of run_service(), run a GTask, that waits for 0.5s.
If sharing is disabled, read_thread will immediately return and cause the main_loop to stop.
This in turn causes the cancellable object to be canceled and the loop stops.

If nothing happens for 0.5s (no cancel is called), it means, that sharing is enabled,
because read_thread (and main loop) is blocked, and we can call map_drive.

map_drive then enumerates free drive letters, and maps Spice Folder to highest possible
(from Z: to A:).

If all drive letters are already assigned, show a critical error, but
don't stop the service. The folder can still be accessed trough other
means.
---
Changes since v2:
 - Changed for loop to gpoll
 - split map_drive into 2 functions
 - added enum for return values of map_drive
 - added TODO for renaming the drive
 - added explanation for the 0.5 delay into commit log

Changes since v1:
 - Changed GThread to a GTask
 - Only wait half a second, instead of 5

Changes since RFC:
 - Calling WNetAddConnection2() blindly was slow and caause many threads to spawn.
    - Now only call it once, when it is sure, that it will connect.
 - Now connects to a * drive, instead of always Z:
 - Thread is now spawned and joined every time run_service() is called.
---
 Makefile.am           |   4 ++
 spice/spice-webdavd.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 116 insertions(+)

diff --git a/Makefile.am b/Makefile.am
index 6127f93..d8e2d53 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -87,6 +87,10 @@ spice_webdavd_LDADD =		\
 	$(PIE_LDFLAGS)		\
 	$(NULL)

+if OS_WIN32
+spice_webdavd_LDADD += -lnetapi32 -lmpr
+endif
+
 deps.txt:
 	$(AM_V_GEN)rpm -qa | grep $(host_os) | sort | unix2dos > $@

diff --git a/spice/spice-webdavd.c b/spice/spice-webdavd.c
index f9c5cf1..49b1884 100644
--- a/spice/spice-webdavd.c
+++ b/spice/spice-webdavd.c
@@ -737,11 +737,118 @@ open_mux_path (const char *path)
   mux_queue = output_queue_new (G_OUTPUT_STREAM (mux_ostream));
 }

+#ifdef G_OS_WIN32
+typedef enum Tmap_drive_enum
+{
+  MAP_DRIVE_OK,
+  MAP_DRIVE_TRY_AGAIN,
+  MAP_DRIVE_ERROR
+} map_drive_enum;
+
+gchar drive_letter;
+
+static gchar
+get_free_drive_letter(void)
+{
+  const guint32 max_mask = 1 << 25;
+  guint32 drives;
+  guint32 mask;
+  gint i;
+
+  drives = GetLogicalDrives ();
+
+  for (i = 0; i < 26; i++)
+  {
+      mask = max_mask >> i;
+      if ((drives & mask) == 0)
+        return 'z' - i;
+  }
+
+  return 0;
+}
+
+static map_drive_enum
+map_drive(void)
+{
+  gchar local_name[3];
+  gchar remote_name[] = "http://localhost:9843/";
+  NETRESOURCE net_resource;
+  guint32 retval;
+
+  local_name[0] = drive_letter;
+  local_name[1] = ':';
+  local_name[2] = 0;
+
+  net_resource.dwType = RESOURCETYPE_DISK;
+  net_resource.lpLocalName = local_name;
+  net_resource.lpRemoteName = remote_name;
+  net_resource.lpProvider = NULL;
+
+  retval = WNetAddConnection2 (&net_resource, NULL, NULL, CONNECT_TEMPORARY);
+
+  if (retval == NO_ERROR) {
+    g_debug ("map_drive ok");
+    return MAP_DRIVE_OK;
+  } else if (retval == ERROR_ALREADY_ASSIGNED) {
+    g_debug ("map_drive already asigned");
+    return MAP_DRIVE_TRY_AGAIN;
+  } else {
+    g_critical ("map_drive error %d", retval);
+    return MAP_DRIVE_ERROR;
+  }
+}
+
+static void
+map_drive_cb(GTask *task,
+          gpointer source_object,
+          gpointer task_data,
+          GCancellable *cancellable)
+{
+  guint32 timeout = 500; //half a second
+  GCancellable * cancel_map = task_data;
+  GPollFD cancel_pollfd;
+
+  if (!g_cancellable_make_pollfd (cancel_map, &cancel_pollfd))
+  {
+    g_critical ("GPollFD failed to create.");
+    return;
+  }
+
+  if (g_poll (&cancel_pollfd, 1, timeout) <= 0)
+  {
+    while (TRUE)
+    {
+      if ((drive_letter = get_free_drive_letter ()) == 0)
+      {
+        g_critical ("all drive letters already assigned.");
+        break;
+      }
+
+      if (map_drive () != MAP_DRIVE_TRY_AGAIN)
+        break;
+    }
+
+    //TODO: Rename network drive after mapping
+  }
+
+  g_cancellable_release_fd (cancel_map);
+  return;
+}
+#endif
+
 static void
 run_service (void)
 {
   g_debug ("Run service");

+#ifdef G_OS_WIN32
+  GCancellable * cancel_map = g_cancellable_new ();
+  GTask * map_drive_task = g_task_new (NULL, NULL, NULL, NULL);
+  g_task_set_task_data (map_drive_task, cancel_map, NULL);
+  g_task_run_in_thread (map_drive_task, map_drive_cb);
+  g_object_unref (map_drive_task);
+#endif
+
   g_socket_service_start (socket_service);

   cancel = g_cancellable_new ();
@@ -775,6 +882,11 @@ run_service (void)
   g_main_loop_run (loop);
   g_main_loop_unref (loop);

+#ifdef G_OS_WIN32
+  g_cancellable_cancel (cancel_map);
+  g_object_unref (cancel_map);
+#endif
+
   g_cancellable_cancel (cancel);

   g_clear_object (&mux_istream);
--
2.5.0