cgpt supports dev and add/delete/modify commands.

src/platform/vboot_reference/utility/cgpt/cgpt_show.c

 /* 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.
  *
- * Update GPT attribute bits.
+ * Show GPT details.
  */
 #include <getopt.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include "cgpt.h"
 #include "cgptlib_internal.h"
 #include "utility.h"
 
 /* Integers to store parsed argument. */
 static int help, number, verbose;
 
 /* The structure for getopt_long(). When you add/delete any line, please refine
  * attribute_comments[] and third parameter of getopt_long() too.  */
 static struct option show_options[] = {
   {.name = "help", .has_arg = no_argument, .flag = 0, .val = 'h'},
   {.name = "number", .has_arg = no_argument, .flag = 0, .val = 'n'},
   {.name = "verbose", .has_arg = no_argument, .flag = 0, .val = 'v'},
+  { /* last element, which should be zero. */ }
 };
 
 /* Extra information than struct option, please update this structure if you
  * add/remove any line in attribute_options[]. */
 static struct option_details show_options_details[] = {
   /* help */
   { .comment = "print this help",
     .validator = AssignTrue,
     .valid_range = 0,
     .parsed = &help},
   /* number */
   { .comment = "print raw numbers (don't interpret)",
     .validator = AssignTrue,
     .valid_range = 0,
     .parsed = &number},
   /* verbose */
   { .comment = "verbose print",
     .validator = AssignTrue,
     .valid_range = 0,
     .parsed = &verbose},
+  { /* last element, which should be zero. */ }
 };
 
 void ShowHelp() {
   printf("\nUsage: %s show [OPTIONS] device_name\n\n", progname);
   ShowOptions(show_options, show_options_details, ARRAY_COUNT(show_options));
   printf("\n");
 }
 
 /* Generate output like:
  *
@@ skipping 61 matching lines @@
     GuidToStr(&header->disk_uuid, buf);
     printf("%sDisk UUID: %s\n", indent, buf);
   }
 
   printf("%sEntries LBA: %lld\n", indent, (long long)header->entries_lba);
   printf("%sNumber of entries: %d\n", indent, header->number_of_entries);
   printf("%sSize of entry: %d\n", indent, header->size_of_entry);
   printf("%sEntries CRC: 0x%08x\n", indent, header->entries_crc32);
 }
 
-/* Resolves human-readable GPT type.
- * Returns CGPT_OK if found.
- * Returns CGPT_FAILED if no known type found. */
-int ResolveType(const Guid *type, char *buf) {
-  struct {
-    Guid type;
-    char *description;
-  } known[] = {
-   {GPT_ENT_TYPE_UNUSED, "Unused partition"},
-   {GPT_ENT_TYPE_EFI, "EFI partition"},
-   {GPT_ENT_TYPE_CHROMEOS_KERNEL, "ChromeOS kernel"},
-   {GPT_ENT_TYPE_CHROMEOS_ROOTFS, "ChromeOS rootfs"},
-   {GPT_ENT_TYPE_CHROMEOS_RESERVED, "ChromeOS reserved"},
-  };
-  int i;
-
-  for (i = 0; i < ARRAY_COUNT(known); ++i) {
-    if (!Memcmp(type, &known[i].type, sizeof(Guid))) {
-      strcpy(buf, known[i].description);
-      return CGPT_OK;
-    }
-  }
-  return CGPT_FAILED;
-}
-
 void EntriesDetails(GptData *gpt, const int secondary) {
   int i;
 
   for (i = 0; i < GetNumberOfEntries(gpt); ++i) {
     static Guid unused = GPT_ENT_TYPE_UNUSED;
     char contents[256];
 
     GptEntry *entry;
     entry = GetEntry(gpt, secondary, i);
 
@@ skipping 70 matching lines @@
                      "hnv",
                      ARRAY_COUNT(show_options),
                      show_options,
                      show_options_details))
     return CGPT_FAILED;
   if (help != NOT_INITED) {
     ShowHelp();
     return CGPT_FAILED;
   }
 
+  OpenDriveInLastArgument(argc, argv, &drive);
   if (CGPT_OK != OpenDriveInLastArgument(argc, argv, &drive))
     return CGPT_FAILED;
 
   printf(TITLE_FMT, "start", "size", "index", "contents");
   printf(GPT_FMT, 0, GPT_PMBR_SECTOR, "", "PMBR");
 
   if (drive.gpt.valid_headers & MASK_PRIMARY) {
     printf(GPT_FMT, (int)GPT_PMBR_SECTOR,
            (int)GPT_HEADER_SECTOR, "", "Pri GPT header");
     if (verbose) {
@@ skipping 55 matching lines @@
       header = (GptHeader*)drive.gpt.secondary_header;
       HeaderDetails(header, indent);
     }
   }
 
   CheckValid(&drive);
   DriveClose(&drive);
 
   return CGPT_OK;
 }