Nearly complete rewrite of cgpt tool.

vboot_firmware/lib/cgptlib/include/gpt.h

 /* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  *
  * Defines EFI related structure. See more details in EFI 2.3 spec.
  *
  * To download EFI standard, please visit UEFI homepage:
  *    http://www.uefi.org/
  */
 #ifndef VBOOT_REFERENCE_CGPTLIB_GPT_H_
@@ skipping 55 matching lines @@
  * For every drive device, there are 2 headers, primary and secondary.
  * Most of fields are duplicated except my_lba and entries_lba.
  *
  * You may find more details in chapter 5 of EFI standard.
  */
 typedef struct {
   char signature[8];
   uint32_t revision;
   uint32_t size;
   uint32_t header_crc32;
-  uint32_t reserved;
+  uint32_t reserved_zero;
   uint64_t my_lba;
   uint64_t alternate_lba;
   uint64_t first_usable_lba;
   uint64_t last_usable_lba;
   Guid disk_uuid;
 
   uint64_t entries_lba;
   uint32_t number_of_entries;
   uint32_t size_of_entry;
   uint32_t entries_crc32;
-  uint8_t padding[512 - 92]; /* Pad to end of sector */
+  uint8_t reserved_padding[];           /* entire sector reserved for header */
 } GptHeader;
 
 /* GPT partition entry defines the starting and ending LBAs of a partition.
  * It also contains the unique GUID, type, and attribute bits.
  *
  * You may find more details in chapter 5 of EFI standard.
  */
 typedef struct {
   Guid type;
   Guid unique;
   uint64_t starting_lba;
   uint64_t ending_lba;
   uint64_t attributes;
-  uint16_t name[36];  /* UTF-16 encoded partition name */
+  uint16_t name[36];                    /* UTF-16 encoded partition name */
+  uint8_t reserved[];                   /* nothing, really */
 } GptEntry;
 
 #endif  /* VBOOT_REFERENCE_CGPTLIB_GPT_H_ */