Add 'prioritize' command to cgpt tool.

cgpt/cmd_prioritize.c

Index: cgpt/cmd_prioritize.c
diff --git a/cgpt/cmd_prioritize.c b/cgpt/cmd_prioritize.c
new file mode 100644
index 0000000000000000000000000000000000000000..3f345689baa8dd92a45548837aba3b84a1e8d22e
--- /dev/null
+++ b/cgpt/cmd_prioritize.c
@@ -0,0 +1,314 @@
+// 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.
+
+#include "cgpt.h"
+
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <uuid/uuid.h>
+
+#include "cgptlib_internal.h"
+
+static void Usage(void)
+{
+  printf("\nUsage: %s prioritize [OPTIONS] DRIVE\n\n"
+         "Reorder the priority of all active ChromeOS Kernel partitions.\n\n"
+         "Options:\n"
+         "  -P NUM       Highest priority to use in the new ordering. The\n"
+         "                 other partitions will be ranked in decreasing\n"
+         "                 priority while preserving their original order.\n"
+         "                 If necessary the lowest ranks will be coalesced.\n"
+         "                 No active kernels will be lowered to priority 0.\n"
+         "  -i NUM       Specify the partition to make the highest in the new\n"
+         "                 order.\n"
+         "  -f           Friends of the given partition (those with the same\n"
+         "                 starting priority) are also updated to the new\n"
+         "                 highest priority.\n"
+         "\n"
+         "With no options this will set the lowest active kernel to\n"
+         "priority 1 while maintaining the original order.\n"
+         "\n", progname);
+}
+
+//////////////////////////////////////////////////////////////////////////////
+// I want a sorted list of priority groups, where each element in the list
+// contains an unordered list of GPT partition numbers. This is a stupid
+// implementation, but our needs are simple and don't justify the time or space
+// it would take to write a "better" one.
+#define MAX_GROUPS 17                   // 0-15, plus one "higher"
+
+typedef struct {
+  int priority;                         // priority of this group
+  int num_parts;                        // number of partitions in this group
+  uint32_t *part;                       // array of partitions in this group
+} group_t;
+
+typedef struct {
+  int max_parts;                       // max number of partitions in any group
+  int num_groups;                      // number of non-empty groups
+  group_t group[MAX_GROUPS];           // array of groups
+} group_list_t;
+
+
+static group_list_t *NewGroupList(int max_p) {
+  int i;
+  group_list_t *gl = (group_list_t *)malloc(sizeof(group_list_t));
+  require(gl);
+  gl->max_parts = max_p;
+  gl->num_groups = 0;
+  // reserve space for the maximum number of partitions in every group
+  for (i=0; i<MAX_GROUPS; i++) {
+    gl->group[i].priority = -1;
+    gl->group[i].num_parts = 0;
+    gl->group[i].part = (uint32_t *)malloc(sizeof(uint32_t) * max_p);
+    require(gl->group[i].part);
+  }
+
+  return gl;
+}
+
+static void FreeGroups(group_list_t *gl) {
+  int i;
+  for (i=0; i<MAX_GROUPS; i++)
+    free(gl->group[i].part);
+  free(gl);
+}
+
+static void AddToGroup(group_list_t *gl, int priority, int partition) {
+  int i;
+  // See if I've already got a group with this priority
+  for (i=0; i<gl->num_groups; i++)
+    if (gl->group[i].priority == priority)
+      break;
+  if (i == gl->num_groups) {
+    // no, add a group
+    require(i < MAX_GROUPS);
+    gl->num_groups++;
+    gl->group[i].priority = priority;
+  }
+  // add the partition to it
+  int j = gl->group[i].num_parts;
+  gl->group[i].part[j] = partition;
+  gl->group[i].num_parts++;
+}
+
+static void ChangeGroup(group_list_t *gl, int old_priority, int new_priority) {
+  int i;
+  for (i=0; i<gl->num_groups; i++)
+    if (gl->group[i].priority == old_priority) {
+      gl->group[i].priority = new_priority;
+      break;
+    }
+}
+
+static void SortGroups(group_list_t *gl) {
+  int i, j;
+  group_t tmp;
+
+  // straight insertion sort is fast enough
+  for (i=1; i<gl->num_groups; i++) {
+    tmp = gl->group[i];
+    for (j=i; j && (gl->group[j-1].priority < tmp.priority); j--)
+      gl->group[j] = gl->group[j-1];
+    gl->group[j] = tmp;
+  }
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+
+int cmd_prioritize(int argc, char *argv[]) {
+  struct drive drive;
+  uint32_t set_partition = 0;
+  int set_friends = 0;
+  int max_priority = 0;
+  int priority;
+  int orig_priority = 0;
+  int gpt_retval;
+  GptEntry *entry;
+  uint32_t index;
+  uint32_t max_part;
+  int num_kernels;
+  int i,j;
+  group_list_t *groups;
+
+  int c;
+  int errorcnt = 0;
+  char *e = 0;
+
+  opterr = 0;                     // quiet, you
+  while ((c=getopt(argc, argv, ":hi:fP:")) != -1)
+  {
+    switch (c)
+    {
+    case 'i':
+      set_partition = (uint32_t)strtoul(optarg, &e, 0);
+      if (!*optarg || (e && *e))
+      {
+        Error("invalid argument to -%c: \"%s\"\n", c, optarg);
+        errorcnt++;
+      }
+      break;
+    case 'f':
+      set_friends = 1;
+      break;
+    case 'P':
+      max_priority = (int)strtol(optarg, &e, 0);
+      if (!*optarg || (e && *e))
+      {
+        Error("invalid argument to -%c: \"%s\"\n", c, optarg);
+        errorcnt++;
+      }
+      if (max_priority < 1 || max_priority > 15) {
+        Error("value for -%c must be between 1 and 15\n", c);
+        errorcnt++;
+      }
+      break;
+
+    case 'h':
+      Usage();
+      return CGPT_OK;
+    case '?':
+      Error("unrecognized option: -%c\n", optopt);
+      errorcnt++;
+      break;
+    case ':':
+      Error("missing argument to -%c\n", optopt);
+      errorcnt++;
+      break;
+    default:
+      errorcnt++;
+      break;
+    }
+  }
+  if (errorcnt)
+  {
+    Usage();
+    return CGPT_FAILED;
+  }
+
+  if (set_friends && !set_partition) {
+    Error("the -f option is only useful with the -i option\n");
+    Usage();
+    return CGPT_FAILED;
+  }
+
+  if (optind >= argc) {
+    Error("missing drive argument\n");
+    return CGPT_FAILED;
+  }
+
+  if (CGPT_OK != DriveOpen(argv[optind], &drive))
+    return CGPT_FAILED;
+
+  if (GPT_SUCCESS != (gpt_retval = GptSanityCheck(&drive.gpt))) {
+    Error("GptSanityCheck() returned %d: %s\n",
+          gpt_retval, GptError(gpt_retval));
+    return CGPT_FAILED;
+  }
+
+  max_part = GetNumberOfEntries(&drive.gpt);
+
+  if (set_partition) {
+    if (set_partition < 1 || set_partition > max_part) {
+      Error("invalid partition number: %d (must be between 1 and %d\n",
+            set_partition, max_part);
+      goto bad;
+    }
+    index = set_partition - 1;
+    // it must be a kernel
+    entry = GetEntry(&drive.gpt, PRIMARY, index);
+    if (!GuidEqual(&entry->type, &guid_chromeos_kernel)) {
+      Error("partition %d is not a ChromeOS kernel\n", set_partition);
+      goto bad;
+    }
+  }
+
+  // How many kernel partitions do I have?
+  num_kernels = 0;
+  for (i = 0; i < max_part; i++) {
+    entry = GetEntry(&drive.gpt, PRIMARY, i);
+    if (GuidEqual(&entry->type, &guid_chromeos_kernel))
+      num_kernels++;
+  }
+
+  if (!num_kernels)
+    // nothing to do, so don't
+    goto good;
+
+  // Determine the current priority groups
+  groups = NewGroupList(num_kernels);
+  for (i = 0; i < max_part; i++) {
+    entry = GetEntry(&drive.gpt, PRIMARY, i);
+    if (!GuidEqual(&entry->type, &guid_chromeos_kernel))
+      continue;
+
+    priority = GetPriority(&drive.gpt, PRIMARY, i);
+
+    // Is this partition special?
+    if (set_partition && (i+1 == set_partition)) {
+      orig_priority = priority;         // remember the original priority
+      if (set_friends)
+        AddToGroup(groups, priority, i); // we'll move them all later
+      else
+        AddToGroup(groups, 99, i);      // move only this one
+    } else {
+      AddToGroup(groups, priority, i);  // just remember
+    }
+  }
+
+  // If we're including friends, then change the original group priority
+  if (set_partition && set_friends) {
+    ChangeGroup(groups, orig_priority, 99);
+  }
+
+  // Sorting gives the new order. Now we just need to reassign the
+  // priorities.
+  SortGroups(groups);
+
+  // We'll never lower anything to zero, so if the last group is priority zero
+  // we can ignore it.
+  i = groups->num_groups;
+  if (groups->group[i-1].priority == 0)
+    groups->num_groups--;
+
+  // Where do we start?
+  if (max_priority)
+    priority = max_priority;
+  else
+    priority = groups->num_groups > 15 ? 15 : groups->num_groups;
+
+  // Figure out what the new values should be
+  for (i=0; i<groups->num_groups; i++) {
+    groups->group[i].priority = priority;
+    if (priority > 1)
+      priority--;
+  }
+
+  // Now apply the ranking to the GPT
+  for (i=0; i<groups->num_groups; i++)
+    for (j=0; j<groups->group[i].num_parts; j++)
+      SetPriority(&drive.gpt, PRIMARY,
+                  groups->group[i].part[j], groups->group[i].priority);
+
+  FreeGroups(groups);
+
+
+  // Write it all out
+good:
+  RepairEntries(&drive.gpt, MASK_PRIMARY);
+  RepairHeader(&drive.gpt, MASK_PRIMARY);
+
+  drive.gpt.modified |= (GPT_MODIFIED_HEADER1 | GPT_MODIFIED_ENTRIES1 |
+                         GPT_MODIFIED_HEADER2 | GPT_MODIFIED_ENTRIES2);
+  UpdateCrc(&drive.gpt);
+
+  return DriveClose(&drive, 1);
+
+bad:
+  (void) DriveClose(&drive, 0);
+  return CGPT_FAILED;
+}