render: introduce wlr_renderer_get_drm_fd

include/render/gles2.h

@@ -35,6 +35,7 @@ struct wlr_gles2_renderer {
 	struct wlr_renderer wlr_renderer;
 
 	struct wlr_egl *egl;
+	int drm_fd;
 
 	const char *exts_str;
 	struct {

include/wlr/render/interface.h

@@ -72,6 +72,7 @@ struct wlr_renderer_impl {
 	bool (*blit_dmabuf)(struct wlr_renderer *renderer,
 		struct wlr_dmabuf_attributes *dst,
 		struct wlr_dmabuf_attributes *src);
+	int (*get_drm_fd)(struct wlr_renderer *renderer);
 };
 
 void wlr_renderer_init(struct wlr_renderer *renderer,

include/wlr/render/wlr_renderer.h

@@ -131,6 +131,13 @@ bool wlr_renderer_format_supported(struct wlr_renderer *r,
 bool wlr_renderer_init_wl_display(struct wlr_renderer *r,
 	struct wl_display *wl_display);
 
+/**
+ * Obtains the FD of the DRM device used for rendering, or -1 if unavailable.
+ *
+ * The caller doesn't have ownership of the FD, it must not close it.
+ */
+int wlr_renderer_get_drm_fd(struct wlr_renderer *r);
+
 /**
  * Destroys this wlr_renderer. Textures must be destroyed separately.
  */

render/gles2/renderer.c

@@ -4,6 +4,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 #include <wayland-server-protocol.h>
 #include <wayland-util.h>
 #include <wlr/render/egl.h>
@@ -644,6 +645,17 @@ static bool gles2_init_wl_display(struct wlr_renderer *wlr_renderer,
 	return true;
 }
 
+static int gles2_get_drm_fd(struct wlr_renderer *wlr_renderer) {
+	struct wlr_gles2_renderer *renderer =
+		gles2_get_renderer(wlr_renderer);
+
+	if (renderer->drm_fd < 0) {
+		renderer->drm_fd = wlr_egl_dup_drm_fd(renderer->egl);
+	}
+
+	return renderer->drm_fd;
+}
+
 struct wlr_egl *wlr_gles2_renderer_get_egl(struct wlr_renderer *wlr_renderer) {
 	struct wlr_gles2_renderer *renderer =
 		gles2_get_renderer(wlr_renderer);
@@ -675,6 +687,10 @@ static void gles2_destroy(struct wlr_renderer *wlr_renderer) {
 
 	wlr_egl_unset_current(renderer->egl);
 
+	if (renderer->drm_fd >= 0) {
+		close(renderer->drm_fd);
+	}
+
 	free(renderer);
 }
 
@@ -700,6 +716,7 @@ static const struct wlr_renderer_impl renderer_impl = {
 	.texture_from_dmabuf = gles2_texture_from_dmabuf,
 	.init_wl_display = gles2_init_wl_display,
 	.blit_dmabuf = gles2_blit_dmabuf,
+	.get_drm_fd = gles2_get_drm_fd,
 };
 
 void push_gles2_debug_(struct wlr_gles2_renderer *renderer,
@@ -856,6 +873,7 @@ struct wlr_renderer *wlr_gles2_renderer_create(struct wlr_egl *egl) {
 
 	renderer->egl = egl;
 	renderer->exts_str = exts_str;
+	renderer->drm_fd = -1;
 
 	wlr_log(WLR_INFO, "Using %s", glGetString(GL_VERSION));
 	wlr_log(WLR_INFO, "GL vendor: %s", glGetString(GL_VENDOR));

render/wlr_renderer.c

@@ -269,3 +269,10 @@ struct wlr_renderer *wlr_renderer_autocreate(struct wlr_egl *egl,
 
 	return renderer;
 }
+
+int wlr_renderer_get_drm_fd(struct wlr_renderer *r) {
+	if (!r->impl->get_drm_fd) {
+		return -1;
+	}
+	return r->impl->get_drm_fd(r);
+}