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      1 // Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 
      6 #include <string.h>
      7 
      8 #include "cgpt.h"
      9 #include "cgptlib_internal.h"
     10 #include "vboot_host.h"
     11 
     12 static void AllocAndClear(uint8_t **buf, uint64_t size) {
     13   if (*buf) {
     14     memset(*buf, 0, size);
     15   } else {
     16     *buf = calloc(1, size);
     17     if (!*buf) {
     18       Error("Cannot allocate %lu bytes.\n", size);
     19       abort();
     20     }
     21   }
     22 }
     23 
     24 static int GptCreate(struct drive *drive, CgptCreateParams *params) {
     25   // Allocate and/or erase the data.
     26   // We cannot assume the GPT headers or entry arrays have been allocated
     27   // by GptLoad() because those fields might have failed validation checks.
     28   AllocAndClear(&drive->gpt.primary_header,
     29                 drive->gpt.sector_bytes * GPT_HEADER_SECTORS);
     30   AllocAndClear(&drive->gpt.secondary_header,
     31                 drive->gpt.sector_bytes * GPT_HEADER_SECTORS);
     32 
     33   drive->gpt.modified |= (GPT_MODIFIED_HEADER1 | GPT_MODIFIED_ENTRIES1 |
     34                          GPT_MODIFIED_HEADER2 | GPT_MODIFIED_ENTRIES2);
     35 
     36   // Initialize a blank set
     37   if (!params->zap) {
     38     GptHeader *h = (GptHeader *)drive->gpt.primary_header;
     39     memcpy(h->signature, GPT_HEADER_SIGNATURE, GPT_HEADER_SIGNATURE_SIZE);
     40     h->revision = GPT_HEADER_REVISION;
     41     h->size = sizeof(GptHeader);
     42     h->my_lba = GPT_PMBR_SECTORS;  /* The second sector on drive. */
     43     h->alternate_lba = drive->gpt.gpt_drive_sectors - GPT_HEADER_SECTORS;
     44     if (CGPT_OK != GenerateGuid(&h->disk_uuid)) {
     45       Error("Unable to generate new GUID.\n");
     46       return -1;
     47     }
     48 
     49     /* Calculate number of entries */
     50     h->size_of_entry = sizeof(GptEntry);
     51     h->number_of_entries = MAX_NUMBER_OF_ENTRIES;
     52     if (drive->gpt.flags & GPT_FLAG_EXTERNAL) {
     53       // We might have smaller space for the GPT table. Scale accordingly.
     54       //
     55       // +------+------------+---------------+-----+--------------+-----------+
     56       // | PMBR | Prim. Head | Prim. Entries | ... | Sec. Entries | Sec. Head |
     57       // +------+------------+---------------+-----+--------------+-----------+
     58       //
     59       // Half the size of gpt_drive_sectors must be big enough to hold PMBR +
     60       // GPT Header + Entries Table, though the secondary structures do not
     61       // contain PMBR.
     62       size_t required_headers_size =
     63           (GPT_PMBR_SECTORS + GPT_HEADER_SECTORS) * drive->gpt.sector_bytes;
     64       size_t min_entries_size = MIN_NUMBER_OF_ENTRIES * h->size_of_entry;
     65       size_t required_min_size = required_headers_size + min_entries_size;
     66       size_t half_size =
     67           (drive->gpt.gpt_drive_sectors / 2) * drive->gpt.sector_bytes;
     68       if (half_size < required_min_size) {
     69         Error("Not enough space to store GPT structures. Required %d bytes.\n",
     70               required_min_size * 2);
     71         return -1;
     72       }
     73       size_t max_entries =
     74           (half_size - required_headers_size) / h->size_of_entry;
     75       if (h->number_of_entries > max_entries) {
     76         h->number_of_entries = max_entries;
     77       }
     78     }
     79 
     80     /* Then use number of entries to calculate entries_lba. */
     81     h->entries_lba = h->my_lba + GPT_HEADER_SECTORS;
     82     if (!(drive->gpt.flags & GPT_FLAG_EXTERNAL)) {
     83       h->entries_lba += params->padding;
     84       h->first_usable_lba = h->entries_lba + CalculateEntriesSectors(h);
     85       h->last_usable_lba = (drive->gpt.streaming_drive_sectors - GPT_HEADER_SECTORS -
     86                             CalculateEntriesSectors(h) - 1);
     87     } else {
     88       h->first_usable_lba = params->padding;
     89       h->last_usable_lba = (drive->gpt.streaming_drive_sectors - 1);
     90     }
     91 
     92     size_t entries_size = h->number_of_entries * h->size_of_entry;
     93     AllocAndClear(&drive->gpt.primary_entries, entries_size);
     94     AllocAndClear(&drive->gpt.secondary_entries, entries_size);
     95 
     96     // Copy to secondary
     97     RepairHeader(&drive->gpt, MASK_PRIMARY);
     98 
     99     UpdateCrc(&drive->gpt);
    100   }
    101 
    102   return 0;
    103 }
    104 
    105 int CgptCreate(CgptCreateParams *params) {
    106   struct drive drive;
    107 
    108   if (params == NULL)
    109     return CGPT_FAILED;
    110 
    111   if (CGPT_OK != DriveOpen(params->drive_name, &drive, O_RDWR,
    112                            params->drive_size))
    113     return CGPT_FAILED;
    114 
    115   if (GptCreate(&drive, params))
    116     goto bad;
    117 
    118   // Write it all out
    119   return DriveClose(&drive, 1);
    120 
    121 bad:
    122 
    123   DriveClose(&drive, 0);
    124   return CGPT_FAILED;
    125 }
    126