dmabuf: Add gdk_dmabuf_sanitize()

Tries to sanitize the dmabuf to conform to the values expected
by Vulkan/EGL which should also be the values expected by
Wayland compositors

We put these sanitized values into the GdkDmabufTexture, by
sanitizing the input from GdkDmabufTextureBuilder, which are
controlled by the callers.

Things we do here:

1. Disallow any dmabuf format that we do not know.

1. Treat the INVALID modifier the same as LINEAR.

2. Ignore all other modifiers.

3. Try and fix various inconsistencies between V4L and Mesa,
   like NV12.

*** WARNING ***

This function is not absolutely perfect, you do not have a
perfect dmabuf afterwards.

In particular, it doesn't check sizes.

gdk/gdkdmabuf.c

@@ -206,4 +206,77 @@ gdk_dmabuf_get_direct_downloader (void)
   return &downloader;
 }
 
+/* 
+ * Tries to sanitize the dmabuf to conform to the values expected
+ * by Vulkan/EGL which should also be the values expected by
+ * Wayland compositors
+ *
+ * We put these sanitized values into the GdkDmabufTexture, by
+ * sanitizing the input from GdkDmabufTextureBuilder, which are
+ * controlled by the callers.
+ *
+ * Things we do here:
+ * 
+ * 1. Disallow any dmabuf format that we do not know.
+ *
+ * 1. Treat the INVALID modifier the same as LINEAR.
+ *
+ * 2. Ignore all other modifiers.
+ *
+ * 3. Try and fix various inconsistencies between V4L and Mesa,
+ *    like NV12.
+ *
+ * *** WARNING ***
+ *
+ * This function is not absolutely perfect, you do not have a
+ * perfect dmabuf afterwards.
+ *
+ * In particular, it doesn't check sizes.
+ *
+ * *** WARNING ***
+ */
+gboolean
+gdk_dmabuf_sanitize (GdkDmabuf        *dest,
+                     gsize             width,
+                     gsize             height,
+                     const GdkDmabuf  *src,
+                     GError          **error)
+{
+  const GdkDrmFormatInfo *info;
+
+  info = get_drm_format_info (src->fourcc);
+
+  if (info == NULL)
+    {
+      g_set_error (error,
+                   GDK_DMABUF_ERROR, GDK_DMABUF_ERROR_UNSUPPORTED_FORMAT,
+                   "Unsupported dmabuf format %.4s",
+                   (char *) &src->fourcc);
+      return FALSE;
+    }
+
+  *dest = *src;
+
+  if (src->modifier && src->modifier != DRM_FORMAT_MOD_INVALID)
+    return TRUE;
+
+  switch (dest->fourcc)
+    {
+      case DRM_FORMAT_NV12:
+        if (dest->n_planes == 1)
+          {
+            dest->n_planes = 2;
+            dest->planes[1].fd = dest->planes[0].fd;
+            dest->planes[1].stride = dest->planes[0].stride;
+            dest->planes[1].offset = dest->planes[0].offset + dest->planes[0].stride * height;
+          }
+        break;
+
+      default:
+        break;
+    }
+
+  return TRUE;
+}
+
 #endif  /* HAVE_LINUX_DMA_BUF_H */

gdk/gdkdmabufprivate.h

@@ -41,4 +41,10 @@ struct _GdkDmabufDownloader
 #ifdef HAVE_LINUX_DMA_BUF_H
 const GdkDmabufDownloader *
                         gdk_dmabuf_get_direct_downloader        (void) G_GNUC_CONST;
+
+gboolean                gdk_dmabuf_sanitize                     (GdkDmabuf                      *dest,
+                                                                 gsize                           width,
+                                                                 gsize                           height,
+                                                                 const GdkDmabuf                *src,
+                                                                 GError                        **error);
 #endif

gdk/gdkdmabuftexture.c

@@ -22,6 +22,7 @@
 
 #include "gdkdisplayprivate.h"
 #include "gdkdmabufformatsbuilderprivate.h"
+#include "gdkdmabufprivate.h"
 #include "gdktextureprivate.h"
 #include <gdk/gdkglcontext.h>
 #include <gdk/gdkgltexturebuilder.h>
@@ -132,13 +133,22 @@ gdk_dmabuf_texture_new_from_builder (GdkDmabufTextureBuilder *builder,
   GdkDmabufTexture *self;
   GdkTexture *update_texture;
   GdkDisplay *display;
-  const GdkDmabuf *dmabuf;
+  GdkDmabuf dmabuf;
   GdkMemoryFormat format;
   GError *local_error = NULL;
+  int width, height;
   gsize i;
 
   display = gdk_dmabuf_texture_builder_get_display (builder);
-  dmabuf = gdk_dmabuf_texture_builder_get_dmabuf (builder);
+  width = gdk_dmabuf_texture_builder_get_width (builder);
+  height = gdk_dmabuf_texture_builder_get_height (builder);
+  
+  if (!gdk_dmabuf_sanitize (&dmabuf,
+                            width,
+                            height,
+                            gdk_dmabuf_texture_builder_get_dmabuf (builder),
+                            error))
+    return NULL;
 
   gdk_display_init_dmabuf (display);
 
@@ -149,7 +159,7 @@ gdk_dmabuf_texture_new_from_builder (GdkDmabufTextureBuilder *builder,
 
       if (display->dmabuf_downloaders[i]->supports (display->dmabuf_downloaders[i],
                                                     display,
-                                                    dmabuf,
+                                                    &dmabuf,
                                                     gdk_dmabuf_texture_builder_get_premultiplied (builder),
                                                     &format,
                                                     local_error ? NULL : &local_error))
@@ -163,14 +173,14 @@ gdk_dmabuf_texture_new_from_builder (GdkDmabufTextureBuilder *builder,
     }
 
   self = g_object_new (GDK_TYPE_DMABUF_TEXTURE,
-                       "width", gdk_dmabuf_texture_builder_get_width (builder),
-                       "height", gdk_dmabuf_texture_builder_get_height (builder),
+                       "width", width,
+                       "height", height,
                        NULL);
 
   GDK_TEXTURE (self)->format = format;
   g_set_object (&self->display, display);
   self->downloader = display->dmabuf_downloaders[i];
-  self->dmabuf = *dmabuf;
+  self->dmabuf = dmabuf;
   self->destroy = destroy;
   self->data = data;