From ee4e1d5807ebbf340aa466756cc1182b7421a0b0 Mon Sep 17 00:00:00 2001
From: Warner Losh <imp@FreeBSD.org>
Date: Mon, 23 Jul 2018 20:36:25 +0000
Subject: [PATCH] Implement efi_devpath_to_media_path

Takes a generic device path as its input. Scans through it to find the
first media_path node in it and returns a pointer to it. If none is
found, NULL is returned.

Sponsored by: Netflix
---
 stand/efi/include/efilib.h |  1 +
 stand/efi/libefi/devpath.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/stand/efi/include/efilib.h b/stand/efi/include/efilib.h
index 91a7e95f1c22..4272d321e70b 100644
--- a/stand/efi/include/efilib.h
+++ b/stand/efi/include/efilib.h
@@ -88,6 +88,7 @@ bool efi_devpath_match(EFI_DEVICE_PATH *, EFI_DEVICE_PATH *);
 bool efi_devpath_is_prefix(EFI_DEVICE_PATH *, EFI_DEVICE_PATH *);
 CHAR16 *efi_devpath_name(EFI_DEVICE_PATH *);
 void efi_free_devpath_name(CHAR16 *);
+EFI_DEVICE_PATH *efi_devpath_to_media_path(EFI_DEVICE_PATH *);
 
 int efi_status_to_errno(EFI_STATUS);
 EFI_STATUS errno_to_efi_status(int errno);
diff --git a/stand/efi/libefi/devpath.c b/stand/efi/libefi/devpath.c
index f881cfce9896..f02a145eed8b 100644
--- a/stand/efi/libefi/devpath.c
+++ b/stand/efi/libefi/devpath.c
@@ -195,3 +195,19 @@ efi_devpath_is_prefix(EFI_DEVICE_PATH *prefix, EFI_DEVICE_PATH *path)
 	}
 	return (true);
 }
+
+/*
+ * Skip over the 'prefix' part of path and return the part of the path
+ * that starts with the first node that's a MEDIA_DEVICE_PATH.
+ */
+EFI_DEVICE_PATH *
+efi_devpath_to_media_path(EFI_DEVICE_PATH *path)
+{
+
+	while (!IsDevicePathEnd(path)) {
+		if (DevicePathType(path) == MEDIA_DEVICE_PATH)
+			return (path);
+		path = NextDevicePathNode(path);
+	}
+	return (NULL);
+}