svn commit: r324359 - in head/sys/boot/efi: include libefi

[Warner Losh]

Author: imp
Date: Fri Oct  6 12:20:24 2017
New Revision: 324359
URL: https://svnweb.freebsd.org/changeset/base/324359

Log:
  Add efi_devpath_is_prefix
  
  efi_devpath_is_prefix determines if a path matches a passed-in prefix.
  
  Differential Revision: https://reviews.freebsd.org/D12564
  Submitted by: Eric McCorkle

Modified:
  head/sys/boot/efi/include/efilib.h
  head/sys/boot/efi/libefi/devpath.c

Modified: head/sys/boot/efi/include/efilib.h
==============================================================================
--- head/sys/boot/efi/include/efilib.h	Fri Oct  6 11:48:09 2017	(r324358)
+++ head/sys/boot/efi/include/efilib.h	Fri Oct  6 12:20:24 2017	(r324359)
@@ -82,6 +82,7 @@ EFI_HANDLE efi_devpath_handle(EFI_DEVICE_PATH *);
 EFI_DEVICE_PATH *efi_devpath_last_node(EFI_DEVICE_PATH *);
 EFI_DEVICE_PATH *efi_devpath_trim(EFI_DEVICE_PATH *);
 bool efi_devpath_match(EFI_DEVICE_PATH *, EFI_DEVICE_PATH *);
+int efi_devpath_is_prefix(EFI_DEVICE_PATH *, EFI_DEVICE_PATH *);
 CHAR16 *efi_devpath_name(EFI_DEVICE_PATH *);
 void efi_free_devpath_name(CHAR16 *);
 

Modified: head/sys/boot/efi/libefi/devpath.c
==============================================================================
--- head/sys/boot/efi/libefi/devpath.c	Fri Oct  6 11:48:09 2017	(r324358)
+++ head/sys/boot/efi/libefi/devpath.c	Fri Oct  6 12:20:24 2017	(r324359)
@@ -166,3 +166,32 @@ efi_devpath_match(EFI_DEVICE_PATH *devpath1, EFI_DEVIC
 	}
 	return (true);
 }
+
+int
+efi_devpath_is_prefix(EFI_DEVICE_PATH *prefix, EFI_DEVICE_PATH *path)
+{
+	int len;
+
+	if (prefix == NULL || path == NULL)
+		return (0);
+
+	while (1) {
+		if (IsDevicePathEnd(prefix))
+			break;
+
+		if (DevicePathType(prefix) != DevicePathType(path) ||
+		    DevicePathSubType(prefix) != DevicePathSubType(path))
+			return (0);
+
+		len = DevicePathNodeLength(prefix);
+		if (len != DevicePathNodeLength(path))
+			return (0);
+
+		if (memcmp(prefix, path, (size_t)len) != 0)
+			return (0);
+
+		prefix = NextDevicePathNode(prefix);
+		path = NextDevicePathNode(path);
+	}
+	return (1);
+}