Function patch_vbios

util/intelvbttool/intelvbttool.c:1021–1079

* Patch an Intel Option ROM with new VBT. * Caller has to make sure that VBIOS and VBT are valid. * Return 1 on error. */

 * Return 1 on error.
 */
static int patch_vbios(struct fileobject *fo,
		       const struct fileobject *fo_vbt)
{
	optionrom_header_t *oh = (optionrom_header_t *)fo->data;
	struct vbt_header *head;

	struct fileobject *old_vbt = NULL;
	parse_vbios(fo, &old_vbt);

	if (old_vbt) {
		if (oh->vbt_offset + vbt_size(old_vbt) == fo->size) {
			/* Located at the end of file - reduce file size */
			if (fo->size < vbt_size(old_vbt)) {
				free_fo(old_vbt);
				return 1;
			}
			fo = remalloc_fo(fo, fo->size - vbt_size(old_vbt));
			if (!fo) {
				printerr("Failed to allocate memory\n");
				free_fo(old_vbt);
				return 1;
			}
			oh = (optionrom_header_t *)fo->data;
			oh->vbt_offset = 0;
		} else if (vbt_size(old_vbt) < vbt_size(fo_vbt)) {
			/* In the middle of the file - Remove old VBT */
			memset(fo->data + oh->vbt_offset, 0xff,
			       vbt_size(old_vbt));
			oh->vbt_offset = 0;
		} else {
			/* New VBT overwrites existing one - Clear memory */
			memset(fo->data + oh->vbt_offset, 0xff,
			       vbt_size(old_vbt));
		}

		free_fo(old_vbt);
	}

	if (!oh->vbt_offset) {
		print("increasing VBIOS to append VBT\n");
		if ((fo->size + vbt_size(fo_vbt)) >= 2 * 64 * KiB) {
			printerr("VBT won't fit\n");
			return 1;
		}

		oh->vbt_offset = fo->size;
		fo = remalloc_fo(fo, fo->size + vbt_size(fo_vbt));
		if (!fo) {
			printerr("Failed to allocate memory\n");
			return 1;
		}
		oh = (optionrom_header_t *)fo->data;
	}

	head = (struct vbt_header *)((u8 *)oh + oh->vbt_offset);
	memcpy(head, fo_vbt->data, vbt_size(fo_vbt));

	return 0;