// Copyright 2016 The Fuchsia 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 <ctype.h>
#include <fidl/fuchsia.device/cpp/wire.h>
#include <fidl/fuchsia.hardware.block/cpp/wire.h>
#include <getopt.h>
#include <inttypes.h>
#include <lib/component/incoming/cpp/protocol.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <zircon/errors.h>
#include <zircon/status.h>
#include <zircon/syscalls.h>  // for zx_cprng_draw

#include <optional>

#include <gpt/cros.h>
#include <gpt/gpt.h>
#include <gpt/guid.h>

#include "src/storage/lib/block_client/cpp/remote_block_device.h"

using gpt::GptDevice;
using gpt::GuidProperties;
using gpt::KnownGuid;
using gpt::PartitionScheme;

namespace {

const char* bin_name;
bool confirm_writes = true;

zx_status_t ReadPartitionIndex(const char* arg, uint32_t* idx) {
  char* end;
  uint64_t lidx = strtoul(arg, &end, 10);
  if (*end != 0 || lidx > UINT32_MAX || lidx >= gpt::kPartitionCount) {
    return ZX_ERR_INVALID_ARGS;
  }

  *idx = static_cast<uint32_t>(lidx);
  return ZX_OK;
}

void Usage() {
  printf("Usage:\n");
  printf("Note that for all these commands, [<dev>] is the device containing the GPT.\n");
  printf("Although using a GPT will split your device into small partitions, [<dev>] \n");
  printf("should always refer to the containing device, NOT block devices representing\n");
  printf("the partitions themselves.\n\n");
  printf("> %s dump [<dev>]\n", bin_name);
  printf("  View the properties of the selected device\n");
  printf("> %s init [<dev>]\n", bin_name);
  printf("  Initialize the block device with a GPT\n");
  printf("> %s repartition <dev> [[<label> <type> <size>], ...]\n", bin_name);
  printf("  Destructively repartition the device with the given layout\n");
  printf("    e.g.\n");
  printf("    %s repartition /dev/class/block-core/763", bin_name);
  printf(" esp efi-system 100m sys system 5g blob fuchsia-blob 50%% data cros-data 50%%\n");
  printf("> %s add <start block> <end block> <name> [<dev>]\n", bin_name);
  printf("  Add a partition to the device (and create a GPT if one does not exist)\n");
  printf("  Range of blocks is INCLUSIVE (both start and end). Full device range\n");
  printf("  may be queried using '%s dump'\n", bin_name);
  printf("> %s edit <n> <type type_guid>|<id id_guid> [<dev>]\n", bin_name);
  printf("  Edit the GUID of the nth partition on the device\n");
  printf("> %s edit_cros <n> [-T <tries>] [-S <successful>] [-P <priority] <dev>\n", bin_name);
  printf("  Edit the GUID of the nth partition on the device\n");
  printf("> %s adjust <n> <start block> <end block> [<dev>]\n", bin_name);
  printf("  Move or resize the nth partition on the device\n");
  printf("> %s remove <n> [<dev>]\n", bin_name);
  printf("  Remove the nth partition from the device\n");
  printf("> %s visible <n> true|false [<dev>]\n", bin_name);
  printf("  Set the visibility of the nth partition on the device\n");
  printf("\n");
  printf("Known partition types are:\n");
  for (KnownGuid::const_iterator i = KnownGuid::begin(); i != KnownGuid::end(); i++) {
    printf("        %.*s%s\n", static_cast<int>(i->name().size()), i->name().data(),
           i->scheme() == PartitionScheme::kLegacy ? " [legacy]" : "");
  }
  printf("The following options may be passed in front of any command:\n");
  printf("  --live-dangerously: skip the write confirmation prompt\n");
  printf("  --legacy-scheme: use the legacy partitioning scheme\n");
  printf("  --new-scheme: use the new partitioning scheme\n");
}

int CGetC() {
  uint8_t ch;
  for (;;) {
    ssize_t r = read(0, &ch, 1);
    if (r < 0)
      return static_cast<int>(r);
    if (r == 1)
      return ch;
  }
}

char* CrosFlagsToCString(char* dst, size_t dst_len, uint64_t flags) {
  uint32_t priority = gpt_cros_attr_get_priority(flags);
  uint32_t tries = gpt_cros_attr_get_tries(flags);
  bool successful = gpt_cros_attr_get_successful(flags);
  snprintf(dst, dst_len, "priority=%u tries=%u successful=%u", priority, tries, successful);
  dst[dst_len - 1] = 0;
  return dst;
}

char* FlagsToCString(char* dst, size_t dst_len, const uint8_t* guid, uint64_t flags) {
  if (gpt_cros_is_kernel_guid(guid, GPT_GUID_LEN)) {
    return CrosFlagsToCString(dst, dst_len, flags);
  }
  snprintf(dst, dst_len, "0x%016" PRIx64, flags);
  dst[dst_len - 1] = 0;
  return dst;
}

zx::result<std::unique_ptr<GptDevice>> Init(const char* dev) {
  zx::result block = component::Connect<fuchsia_hardware_block_volume::Volume>(dev);
  if (block.is_error()) {
    fprintf(stderr, "gpt: error opening %s: %s\n", dev, block.status_string());
    return block.take_error();
  }

  const fidl::WireResult result = fidl::WireCall(block.value())->GetInfo();
  if (!result.ok()) {
    fprintf(stderr, "gpt: error getting block info from %s: %s\n", dev,
            result.FormatDescription().c_str());
    return zx::error(result.status());
  }
  const fit::result response = result.value();
  if (response.is_error()) {
    fprintf(stderr, "gpt: error getting block info from %s: %s\n", dev,
            zx_status_get_string(response.error_value()));
    return zx::error(response.error_value());
  }

  fuchsia_hardware_block::wire::BlockInfo info = response.value()->info;
  printf("blocksize=0x%X blocks=%" PRIu64 "\n", info.block_size, info.block_count);

  std::string controller_dev = std::string(dev) + "/device_controller";
  zx::result controller = component::Connect<fuchsia_device::Controller>(controller_dev);
  if (controller.is_error()) {
    fprintf(stderr, "gpt: error opening %s: %s\n", controller_dev.c_str(),
            controller.status_string());
    return controller.take_error();
  }

  zx::result device = block_client::RemoteBlockDevice::Create(std::move(block.value()),
                                                              std::move(controller.value()));
  if (device.is_error()) {
    fprintf(stderr, "Failed to create block client: %s\n", device.status_string());
    return device.take_error();
  }
  zx::result gpt = GptDevice::Create(std::move(device.value()), info.block_size, info.block_count);
  if (gpt.is_error()) {
    fprintf(stderr, "gpt: error initializing GPT from %s: %s\n", dev, gpt.status_string());
    return gpt.take_error();
  }
  return gpt;
}

constexpr void SetXY(unsigned yes, const char** X, const char** Y) {
  if (yes) {
    *X = "\033[7m";
    *Y = "\033[0m";
  } else {
    *X = "";
    *Y = "";
  }
}

uint32_t Dump(const GptDevice* gpt) {
  if (!gpt->Valid()) {
    return 0;
  }
  char name[gpt::kGuidCNameLength];
  char guid[gpt::kGuidStrLength];
  char id[gpt::kGuidStrLength];
  char flags_str[256];
  const char* X;
  const char* Y;
  uint32_t i;
  for (i = 0; i < gpt::kPartitionCount; i++) {
    zx::result<const gpt_partition_t*> entry = gpt->GetPartition(i);
    if (!entry.is_ok())
      break;
    const gpt_partition_t* p = entry.value();
    memset(name, 0, gpt::kGuidCNameLength);
    unsigned diff;
    ZX_ASSERT(gpt->GetDiffs(i, &diff) == ZX_OK);
    SetXY(diff & gpt::kGptDiffName, &X, &Y);
    printf("Partition %u: %s%s%s\n", i, X,
           utf16_to_cstring(name, reinterpret_cast<const uint16_t*>(p->name),
                            gpt::kGuidCNameLength - 1),
           Y);
    SetXY(diff & (gpt::kGptDiffFirst | gpt::kGptDiffLast), &X, &Y);
    printf("    Start: %s%" PRIu64 "%s, End: %s%" PRIu64 "%s (%" PRIu64 " blocks)\n", X, p->first,
           Y, X, p->last, Y, p->last - p->first + 1);
    SetXY(diff & gpt::kGptDiffGuid, &X, &Y);
    uint8_to_guid_string(guid, p->guid);
    printf("    id:   %s%s%s\n", X, guid, Y);
    SetXY(diff & gpt::kGptDiffType, &X, &Y);
    uint8_to_guid_string(id, p->type);
    printf("    type: %s%s%s\n", X, id, Y);
    SetXY(diff & gpt::kGptDiffName, &X, &Y);
    printf("    flags: %s%s%s\n", X,
           FlagsToCString(flags_str, sizeof(flags_str), p->type, p->flags), Y);
  }
  return i;
}

void DumpPartitions(const char* dev) {
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return;
  }
  GptDevice* gpt = gpt_result.value().get();

  if (!gpt->Valid()) {
    fprintf(stderr, "No valid GPT found\n");
    return;
  }

  printf("Partition table is valid\n");

  uint64_t start, end;
  if (gpt->Range(&start, &end) != ZX_OK) {
    fprintf(stderr, "Couldn't identify device range\n");
    return;
  }

  printf("GPT contains usable blocks from %" PRIu64 " to %" PRIu64 " (inclusive)\n", start, end);
  size_t count = Dump(gpt);
  printf("Total: %zu partitions\n", count);
}

bool ConfirmCommit(const GptDevice* gpt, const char* dev) {
  if (confirm_writes) {
    Dump(gpt);
    printf("\n");
    printf("WARNING: About to write partition table to: %s\n", dev);
    printf("WARNING: Type 'y' to continue, 'n' or ESC to cancel\n");

    for (;;) {
      switch (CGetC()) {
        case 'y':
        case 'Y':
          return true;
        case 'n':
        case 'N':
        case 27:
          return false;
      }
    }
  }

  return true;
}

zx_status_t Commit(GptDevice* gpt, const char* dev) {
  if (!ConfirmCommit(gpt, dev)) {
    return ZX_OK;
  }

  if (zx_status_t status = gpt->Sync(); status != ZX_OK) {
    fprintf(stderr, "gpt: device sync failed for %s: %s\n", dev, zx_status_get_string(status));
    return status;
  }

  if (zx::result result = gpt->device().Rebind({}); result.is_error()) {
    fprintf(stderr, "gpt: gpt updated but device %s could not be rebound: %s. Please reboot.\n",
            dev, result.status_string());
    return result.error_value();
  }

  printf("GPT changes complete.\n");
  return ZX_OK;
}

zx_status_t InitGpt(const char* dev) {
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return ZX_ERR_INTERNAL;
  }
  GptDevice* gpt = gpt_result.value().get();

  // generate a default header
  if (zx_status_t status = gpt->RemoveAllPartitions(); status != ZX_OK) {
    fprintf(stderr, "Failed to remove partitions: %s\n", zx_status_get_string(status));
    return status;
  }
  return Commit(gpt, dev);
}

zx_status_t AddPartition(const char* dev, uint64_t start, uint64_t end, const char* name) {
  uint8_t guid[GPT_GUID_LEN];
  zx_cprng_draw(guid, GPT_GUID_LEN);

  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  if (!gpt->Valid()) {
    // generate a default header
    if (Commit(gpt, dev)) {
      return ZX_ERR_INTERNAL;
    }
  }

  uint8_t type[GPT_GUID_LEN];
  memset(type, 0xff, GPT_GUID_LEN);
  zx_status_t rc = gpt->AddPartition(name, type, guid, start, end - start + 1, 0).status_value();
  if (rc != ZX_OK) {
    fprintf(stderr, "Add partition failed: %s\n", zx_status_get_string(rc));
    return rc;
  }
  printf("add partition: name=%s start=%" PRIu64 " end=%" PRIu64 "\n", name, start, end);
  return Commit(gpt, dev);
}

zx_status_t RemovePartition(const char* dev, uint32_t n) {
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  zx::result<const gpt_partition_t*> p = gpt->GetPartition(n);
  if (!p.is_ok()) {
    fprintf(stderr, "Failed to get partition at index %u\n", n);
    return ZX_ERR_INVALID_ARGS;
  }
  char name[gpt::kGuidCNameLength];
  memset(name, 0, gpt::kGuidCNameLength);
  utf16_to_cstring(name, reinterpret_cast<const uint16_t*>((*p)->name), gpt::kGuidCNameLength - 1);
  if (zx_status_t status = gpt->RemovePartition((*p)->guid); status != ZX_OK) {
    fprintf(stderr, "Failed to remove partiton: %s\n", zx_status_get_string(status));
    return status;
  }
  printf("remove partition: n=%u name=%s\n", n, name);
  return Commit(gpt, dev);
}

zx_status_t AdjustPartition(const char* dev, uint32_t idx_part, uint64_t start, uint64_t end) {
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  if (zx_status_t status = gpt->SetPartitionRange(idx_part, start, end); status != ZX_OK) {
    if (status == ZX_ERR_INVALID_ARGS) {
      fprintf(stderr, "partition #%u would be outside of valid block range\n", idx_part);
    } else if (status == ZX_ERR_OUT_OF_RANGE) {
      fprintf(stderr, "New partition range overlaps existing partition(s)\n");
    } else {
      fprintf(stderr, "Edit parition failed: %s\n", zx_status_get_string(status));
    }
    return status;
  }

  return Commit(gpt, dev);
}

/*
 * Edit a partition, changing either its type or ID GUID.
 *
 * dev:         path to the device where the GPT can be read.
 * idx_part:    index of the partition in the GPT that you want to change.
 * type_or_id:  which GUID to change, either "type" or "id".
 * guid:        GUID to assign.
 */
zx_status_t EditPartition(const char* dev, uint32_t idx_part, char* type_or_id,
                          const uint8_t* guid) {
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  if (!guid) {
    return ZX_ERR_INVALID_ARGS;
  }

  zx_status_t status;
  if (!strcmp(type_or_id, "type")) {
    status = gpt->SetPartitionType(idx_part, guid);
  } else if (!strcmp(type_or_id, "id")) {
    status = gpt->SetPartitionGuid(idx_part, guid);
  } else {
    fprintf(stderr, "Invalid arguments to edit partition");
    Usage();
    return ZX_ERR_INVALID_ARGS;
  }

  if (status != ZX_OK) {
    fprintf(stderr, "Edit parition failed: %s\n", zx_status_get_string(status));
    return status;
  }

  return Commit(gpt, dev);
}

struct cros_partition_args_t {
  const char* dev;
  uint32_t idx_part;
  std::optional<int64_t> tries;
  std::optional<int64_t> priority;
  std::optional<int64_t> successful;
};

// Parses arguments for EditCrosPartition. Returns ZX_OK on successfully parsing
// all required arguments. Fields of unpassed optional arguments are left
// unchanged.
zx_status_t GetCrosPartitionArgs(char* const* argv, int argc, cros_partition_args_t* out_args) {
  uint32_t idx_part;
  if (zx_status_t status = ReadPartitionIndex(argv[0], &idx_part); status != ZX_OK) {
    Usage();
    return status;
  }

  char* end;

  int c;
  while ((c = getopt(argc, argv, "T:P:S:")) > 0) {
    switch (c) {
      case 'T': {
        int64_t val = strtol(optarg, &end, 10);
        if (*end != 0 || optarg[0] == 0) {
          Usage();
          return ZX_ERR_INVALID_ARGS;
        }
        if (val < 0 || val > 15) {
          fprintf(stderr, "tries must be in the range [0, 16)\n");
          Usage();
          return ZX_ERR_INVALID_ARGS;
        }
        out_args->tries = val;
        break;
      }
      case 'P': {
        int64_t val = strtol(optarg, &end, 10);
        if (*end != 0 || optarg[0] == 0) {
          Usage();
          return ZX_ERR_INVALID_ARGS;
        }
        if (val < 0 || val > 15) {
          fprintf(stderr, "priority must be in the range [0, 16)\n");
          Usage();
          return ZX_ERR_INVALID_ARGS;
        }
        out_args->priority = val;
        break;
      }
      case 'S': {
        if (!strcmp(optarg, "0")) {
          out_args->successful = 0;
        } else if (!strcmp(optarg, "1")) {
          out_args->successful = 1;
        } else {
          fprintf(stderr, "successful must be 0 or 1\n");
          Usage();
          return ZX_ERR_INVALID_ARGS;
        }
        break;
      }
      default:
        fprintf(stderr, "Unknown option\n");
        Usage();
        return ZX_ERR_INVALID_ARGS;
    }
  }

  if (optind != argc - 1) {
    fprintf(stderr, "Did not specify device arg\n");
    Usage();
    return ZX_ERR_INVALID_ARGS;
  }

  out_args->idx_part = idx_part;
  out_args->dev = argv[optind];
  return ZX_OK;
}

// Edit a Chrome OS kernel partition, changing its attributes.
// argv/argc should correspond only to the arguments after the command.
zx_status_t EditCrosPartition(char* const* argv, int argc) {
  cros_partition_args_t args = {};

  if (zx_status_t status = GetCrosPartitionArgs(argv, argc, &args); status != ZX_OK) {
    return status;
  }

  zx::result gpt_result = Init(args.dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  zx::result<const gpt_partition_t*> part = gpt->GetPartition(args.idx_part);
  if (part.is_error()) {
    fprintf(stderr, "Partition not found at given index\n");
    return ZX_ERR_INVALID_ARGS;
  }

  if (!gpt_cros_is_kernel_guid((*part)->type, GPT_GUID_LEN)) {
    fprintf(stderr, "Partition is not a CrOS kernel partition\n");
    return ZX_ERR_INVALID_ARGS;
  }

  uint64_t flags;
  if (zx_status_t status = gpt->GetPartitionFlags(args.idx_part, &flags); status != ZX_OK) {
    fprintf(stderr, "Failed to get partition flags: %s\n", zx_status_get_string(status));
    return status;
  }

  if (args.tries) {
    if (gpt_cros_attr_set_tries(&flags, static_cast<uint8_t>(*args.tries)) < 0) {
      fprintf(stderr, "Failed to set tries\n");
      return ZX_ERR_INVALID_ARGS;
    }
  }
  if (args.priority) {
    if (gpt_cros_attr_set_priority(&flags, static_cast<uint8_t>(*args.priority)) < 0) {
      fprintf(stderr, "Failed to set priority\n");
      return ZX_ERR_INVALID_ARGS;
    }
  }
  if (args.successful) {
    gpt_cros_attr_set_successful(&flags, *args.successful);
  }

  if (zx_status_t status = gpt->SetPartitionFlags(args.idx_part, flags); status != ZX_OK) {
    fprintf(stderr, "Failed to set partition flags: %s\n", zx_status_get_string(status));
    return status;
  }
  return Commit(gpt, args.dev);
}

/*
 * Set whether a partition is visible or not to the EFI firmware. If a
 * partition is set as hidden, the firmware will not attempt to boot from the
 * partition.
 */
zx_status_t SetVisibility(char* dev, uint32_t idx_part, bool visible) {
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  if (zx_status_t status = gpt->SetPartitionVisibility(idx_part, visible); status != ZX_OK) {
    fprintf(stderr, "Partition visibility edit failed: %s\n", zx_status_get_string(status));
    return status;
  }

  return Commit(gpt, dev);
}

// ParseSize parses long integers in base 10, expanding p, t, g, m, and k
// suffices as binary byte scales. If the suffix is %, the value is returned as
// negative, in order to indicate a proportion.
int64_t ParseSize(char* s) {
  char* end = s;
  int64_t v = strtoll(s, &end, 10);

  switch (*end) {
    case 0:
      break;
    case '%':
      v = -v;
      break;
    case 'p':
    case 'P':
      v *= 1024;
      __FALLTHROUGH;
    case 't':
    case 'T':
      v *= 1024;
      __FALLTHROUGH;
    case 'g':
    case 'G':
      v *= 1024;
      __FALLTHROUGH;
    case 'm':
    case 'M':
      v *= 1024;
      __FALLTHROUGH;
    case 'k':
    case 'K':
      v *= 1024;
  }
  return v;
}

// Looks up the type GUID for the given partition name.
//
// |scheme| is only necessary for names which have both new and legacy mappings
// such as "vbmeta_a".
//
// Returns the GUID if exactly one was found, otherwise returns nullptr and logs
// an error.
const uint8_t* GetTypeGuid(const char* name, std::optional<PartitionScheme> scheme) {
  std::list<const GuidProperties*> matches = KnownGuid::Find(name, std::nullopt, scheme);

  if (matches.empty()) {
    fprintf(stderr, "GUID lookup failed: unknown partition '%s'\n", name);
    return nullptr;
  }

  if (matches.size() > 1) {
    fprintf(stderr,
            "GUID lookup failed: partition '%s' has multiple mappings, please specify a scheme\n",
            name);
    return nullptr;
  }

  return matches.front()->type_guid().bytes();
}

// TODO(raggi): this should eventually get moved into ulib/gpt.
// Align finds the next block at or after base that is aligned to a physical
// block boundary. The gpt specification requires that all partitions are
// aligned to physical block boundaries.
uint64_t Align(uint64_t base, uint64_t logical, uint64_t physical) {
  uint64_t a = logical;
  if (physical > a)
    a = physical;
  uint64_t base_bytes = base * logical;
  uint64_t d = base_bytes % a;
  return (base_bytes + a - d) / logical;
}

// Repartition expects argv to start with the disk path and be followed by
// triples of name, type and size.
zx_status_t Repartition(int argc, char** argv, std::optional<PartitionScheme> scheme) {
  const char* dev = argv[0];
  uint64_t logical, free_space;
  zx::result gpt_result = Init(dev);
  if (gpt_result.is_error()) {
    return gpt_result.error_value();
  }
  GptDevice* gpt = gpt_result.value().get();

  argc--;
  argv = &argv[1];
  ZX_ASSERT(argc > 0);
  size_t num_partitions = static_cast<size_t>(argc / 3);
  zx::result<const gpt_partition_t*> p = gpt->GetPartition(0);
  while (p.is_ok()) {
    ZX_ASSERT(gpt->RemovePartition((*p)->guid) == ZX_OK);
    p = gpt->GetPartition(0);
  }

  logical = gpt->BlockSize();
  free_space = gpt->TotalBlockCount() * logical;

  {
    // expand out any proportional sizes into absolute sizes
    uint64_t sizes[num_partitions];
    memset(sizes, 0, sizeof(sizes));
    {
      uint64_t percent = 100;
      uint64_t portions[num_partitions];
      memset(portions, 0, sizeof(portions));
      for (size_t i = 0; i < num_partitions; i++) {
        int64_t sz = ParseSize(argv[(i * 3) + 2]);
        if (sz > 0) {
          sizes[i] = sz;
          free_space -= sz;
        } else {
          if (percent == 0) {
            fprintf(stderr, "more than 100%% of free space requested\n");
            return ZX_ERR_INVALID_ARGS;
          }
          // portions from ParseSize are negative
          portions[i] = -sz;
          percent -= -sz;
        }
      }
      for (size_t i = 0; i < num_partitions; i++) {
        if (portions[i] != 0)
          sizes[i] = (free_space * portions[i]) / 100;
      }
    }

    // TODO(raggi): get physical block size...
    uint64_t physical = 8192;

    uint64_t first_usable = 0;
    uint64_t last_usable = 0;
    ZX_ASSERT(gpt->Range(&first_usable, &last_usable) == ZX_OK);

    uint64_t start = Align(first_usable, logical, physical);

    for (size_t i = 0; i < num_partitions; i++) {
      char* name = argv[i * 3];
      char* guid_name = argv[(i * 3) + 1];

      uint64_t byte_size = sizes[i];

      const uint8_t* type = GetTypeGuid(guid_name, scheme);
      if (!type) {
        return ZX_ERR_INVALID_ARGS;
      }

      uint8_t guid[GPT_GUID_LEN];
      zx_cprng_draw(guid, GPT_GUID_LEN);

      // end is clamped to the sector before the next aligned partition, in order
      // to avoid wasting alignment space at the tail of partitions.
      uint64_t nblocks = (byte_size / logical) + (byte_size % logical == 0 ? 0 : 1);
      uint64_t end = Align(start + nblocks + 1, logical, physical) - 1;
      if (end > last_usable)
        end = last_usable;

      if (start > last_usable) {
        fprintf(stderr, "partition %s does not fit\n", name);
        return ZX_ERR_OUT_OF_RANGE;
      }

      printf("%s: %" PRIu64 " bytes, %" PRIu64 " blocks, %" PRIu64 "-%" PRIu64 "\n", name,
             byte_size, nblocks, start, end);
      ZX_ASSERT(gpt->AddPartition(name, type, guid, start, end - start, 0).status_value() == ZX_OK);

      start = end + 1;
    }
  }

  return Commit(gpt, dev);
}

}  // namespace

int main(int argc, char** argv) {
  bin_name = argv[0];
  const char* cmd;
  uint32_t idx_part;
  std::optional<PartitionScheme> scheme;

  while (argc > 1) {
    if (!strcmp(argv[1], "--live-dangerously")) {
      confirm_writes = false;
    } else if (!strcmp(argv[1], "--legacy-scheme")) {
      if (scheme) {
        Usage();
        return -1;
      }
      scheme = PartitionScheme::kLegacy;
    } else if (!strcmp(argv[1], "--new-scheme")) {
      if (scheme) {
        Usage();
        return -1;
      }
      scheme = PartitionScheme::kNew;
    } else {
      break;
    }
    argc--;
    argv++;
  }

  if (argc == 1) {
    Usage();
    return -1;
  }

  cmd = argv[1];
  if (!strcmp(cmd, "dump")) {
    if (argc <= 2) {
      Usage();
      return -1;
    }
    DumpPartitions(argv[2]);
  } else if (!strcmp(cmd, "init")) {
    if (argc <= 2) {
      Usage();
      return -1;
    }
    if (InitGpt(argv[2]) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "add")) {
    if (argc <= 5) {
      Usage();
      return -1;
    }
    if (AddPartition(argv[5], strtoull(argv[2], nullptr, 0), strtoull(argv[3], nullptr, 0),
                     argv[4]) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "remove")) {
    if (argc <= 3) {
      Usage();
      return -1;
    }
    if (ReadPartitionIndex(argv[2], &idx_part) != ZX_OK) {
      Usage();
      return -1;
    }
    if (RemovePartition(argv[3], idx_part) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "edit")) {
    if (argc <= 5) {
      Usage();
      return -1;
    }
    if (ReadPartitionIndex(argv[2], &idx_part) != ZX_OK) {
      Usage();
      return -1;
    }
    if (EditPartition(argv[5], idx_part, argv[3], GetTypeGuid(argv[4], scheme)) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "edit_cros")) {
    if (argc <= 4) {
      Usage();
      return -1;
    }
    if (EditCrosPartition(argv + 2, argc - 2) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "adjust")) {
    if (argc <= 5) {
      Usage();
      return -1;
    }
    if (ReadPartitionIndex(argv[2], &idx_part) != ZX_OK) {
      Usage();
      return -1;
    }
    if (AdjustPartition(argv[5], idx_part, strtoull(argv[3], nullptr, 0),
                        strtoull(argv[4], nullptr, 0)) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "visible")) {
    if (argc < 5) {
      Usage();
      return -1;
    }
    bool visible;
    if (!strcmp(argv[3], "true")) {
      visible = true;
    } else if (!strcmp(argv[3], "false")) {
      visible = false;
    } else {
      Usage();
      return -1;
    }

    if (ReadPartitionIndex(argv[2], &idx_part) != ZX_OK) {
      Usage();
      return -1;
    }
    if (SetVisibility(argv[4], idx_part, visible) != ZX_OK) {
      return 1;
    }
  } else if (!strcmp(cmd, "repartition")) {
    if (argc < 6) {
      Usage();
      return -1;
    }
    if (argc % 3 != 0) {
      Usage();
      return -1;
    }
    return Repartition(argc - 2, &argv[2], scheme);
  } else {
    Usage();
    return -1;
  }

  return 0;
}