[c-host] linux: initial xcb capture

c-host/Makefile

@@ -34,6 +34,7 @@ else
 
   ifeq ($(USE_XCB), 1)
     CFLAGS += -DUSE_XCB
+    LIBS   += -lxcb -lxcb-shm -lXfixes
     OBJS   += linux/capture/xcb.o
   endif
 endif

c-host/linux/capture/xcb.c

@@ -0,0 +1,184 @@
+/*
+Looking Glass - KVM FrameRelay (KVMFR) Client
+Copyright (C) 2017-2019 Geoffrey McRae <geoff@hostfission.com>
+https://looking-glass.hostfission.com
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2 of the License, or (at your option) any later
+version.
+
+This program is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+Place, Suite 330, Boston, MA 02111-1307 USA
+*/
+
+#include "capture/interface.h"
+#include "debug.h"
+#include <assert.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <xcb/shm.h>
+#include <xcb/xfixes.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+
+struct xcb
+{
+  bool               initialized;
+  xcb_connection_t * xcb;
+  xcb_screen_t     * xcbScreen;
+  uint32_t           seg;
+  int                shmID;
+  void             * data;
+
+  unsigned int width;
+  unsigned int height;
+
+  xcb_shm_get_image_cookie_t           imgC;
+  xcb_xfixes_get_cursor_image_cookie_t curC;
+};
+
+struct xcb * this = NULL;
+
+// forwards
+
+static bool xcb_deinit();
+static unsigned int xcb_getMaxFrameSize();
+
+// implementation
+
+static const char * xcb_getName()
+{
+  return "XCB";
+}
+
+static bool xcb_create()
+{
+  assert(!this);
+  this        = (struct xcb *)calloc(sizeof(struct xcb), 1);
+  this->shmID = -1;
+  this->data  = (void *)-1;
+  return true;
+}
+
+static bool xcb_init()
+{
+  assert(this);
+  assert(!this->initialized);
+
+  this->xcb = xcb_connect(NULL, NULL);
+  if (!this->xcb || xcb_connection_has_error(this->xcb))
+  {
+    DEBUG_ERROR("Unable to open the X display");
+    goto fail;
+  }
+
+  if (!xcb_get_extension_data(this->xcb, &xcb_shm_id)->present)
+  {
+    DEBUG_ERROR("Missing the SHM extension");
+    goto fail;
+  }
+
+  xcb_screen_iterator_t iter;
+  iter            = xcb_setup_roots_iterator(xcb_get_setup(this->xcb));
+  this->xcbScreen = iter.data;
+  this->width     = iter.data->width_in_pixels;
+  this->height    = iter.data->height_in_pixels;
+  DEBUG_INFO("Frame Size       : %u x %u", this->width, this->height);
+
+  this->seg   = xcb_generate_id(this->xcb);
+  this->shmID = shmget(IPC_PRIVATE, xcb_getMaxFrameSize(), IPC_CREAT | 0777);
+  if (this->shmID == -1)
+  {
+    DEBUG_ERROR("shmget failed");
+    goto fail;
+  }
+
+  xcb_shm_attach(this->xcb, this->seg ,this->shmID, false);
+  this->data = shmat(this->shmID, NULL, 0);
+  if ((uintptr_t)this->data == -1)
+  {
+    DEBUG_ERROR("shmat failed");
+    goto fail;
+  }
+  DEBUG_INFO("Frame Data       : 0x%" PRIXPTR, (uintptr_t)this->data);
+
+  this->initialized = true;
+  return true;
+fail:
+  xcb_deinit();
+  return false;
+}
+
+static bool xcb_deinit()
+{
+  assert(this);
+
+  if ((uintptr_t)this->data != -1)
+  {
+    shmdt(this->data);
+    this->data = (void *)-1;
+  }
+
+  if (this->shmID != -1)
+  {
+    shmctl(this->shmID, IPC_RMID, NULL);
+    this->shmID = -1;
+  }
+
+  if (this->xcb)
+  {
+    xcb_disconnect(this->xcb);
+    this->xcb = NULL;
+  }
+
+  this->initialized = false;
+  return false;
+}
+
+static void xcb_free()
+{
+  free(this);
+  this = NULL;
+}
+
+static unsigned int xcb_getMaxFrameSize()
+{
+  return this->width * this->height * 4;
+}
+
+static CaptureResult xcb_capture(bool * hasFrameUpdate, bool * hasPointerUpdate)
+{
+  assert(this);
+  assert(this->initialized);
+
+  this->imgC = xcb_shm_get_image_unchecked(
+      this->xcb,
+      this->xcbScreen->root,
+      0, 0,
+      this->width,
+      this->height,
+      ~0,
+      XCB_IMAGE_FORMAT_Z_PIXMAP,
+      this->seg,
+      0);
+
+  *hasFrameUpdate = true;
+  return CAPTURE_RESULT_OK;
+}
+
+struct CaptureInterface Capture_XCB =
+{
+  .getName         = xcb_getName,
+  .create          = xcb_create,
+  .init            = xcb_init,
+  .deinit          = xcb_deinit,
+  .free            = xcb_free,
+  .getMaxFrameSize = xcb_getMaxFrameSize,
+  .capture         = xcb_capture
+};