renderer: fixup get_info interface

don't overwrite memory if we get a bad res or info,
return the gbm and virgl formats
use errno return values

src/virglrenderer.c

@@ -141,8 +141,9 @@ int virgl_renderer_resource_get_info(int res_handle,
 {
    int ret;
    ret = vrend_renderer_resource_get_info(res_handle, (struct vrend_renderer_resource_info *)info);
-   info->format = virgl_egl_get_gbm_format(info->format);
+   if (ret == 0)
-   return ret; 
+       info->gbm_format = virgl_egl_get_gbm_format(info->virgl_format);
+   return ret;
 }
 
 void virgl_renderer_get_cap_set(uint32_t cap_set, uint32_t *max_ver,

src/virglrenderer.h

@@ -134,13 +134,14 @@ VIRGL_EXPORT void virgl_renderer_ctx_detach_resource(int ctx_id, int res_handle)
 
 struct virgl_renderer_resource_info {
    uint32_t handle;
-   uint32_t format;
+   uint32_t virgl_format;
    uint32_t width;
    uint32_t height;
    uint32_t depth;
    uint32_t flags;
    uint32_t tex_id;
    uint32_t stride;
+   uint32_t gbm_format;
 };
 
 VIRGL_EXPORT int virgl_renderer_resource_get_info(int res_handle,

src/vrend_renderer.c

@@ -5383,11 +5383,14 @@ static struct vrend_resource *vrend_renderer_ctx_res_lookup(struct vrend_context
 int vrend_renderer_resource_get_info(int res_handle,
                                      struct vrend_renderer_resource_info *info)
 {
-   struct vrend_resource *res = vrend_resource_lookup(res_handle, 0);
+   struct vrend_resource *res;
    int elsize;
 
+   if (!info)
+     return EINVAL;
+   res = vrend_resource_lookup(res_handle, 0);
    if (!res)
-      return -1;
+      return EINVAL;
 
    elsize = util_format_get_blocksize(res->base.format);