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gpt: selectively update fields during repair

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Just a little cleanup/refactor to skip touching data we don't need to.
This commit is contained in:
Michael Marineau 2016-09-21 14:33:48 -07:00
parent 1f5d29420c
commit 427fdc58e1
1 changed files with 12 additions and 16 deletions
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28
grub-core/lib/gpt.c
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@ -577,8 +577,6 @@ grub_gpt_get_partentry (grub_gpt_t gpt, grub_uint32_t n)
grub_err_t grub_err_t
grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt) grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt)
{ {
grub_uint64_t backup_header, backup_entries;
/* Skip if there is nothing to do. */ /* Skip if there is nothing to do. */
if (grub_gpt_both_valid (gpt)) if (grub_gpt_both_valid (gpt))
return GRUB_ERR_NONE; return GRUB_ERR_NONE;
@ -591,6 +589,8 @@ grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt)
if (grub_gpt_primary_valid (gpt)) if (grub_gpt_primary_valid (gpt))
{ {
grub_uint64_t backup_header;
grub_dprintf ("gpt", "primary GPT is valid\n"); grub_dprintf ("gpt", "primary GPT is valid\n");
/* Relocate backup to end if disk if the disk has grown. */ /* Relocate backup to end if disk if the disk has grown. */
@ -601,32 +601,28 @@ grub_gpt_repair (grub_disk_t disk, grub_gpt_t gpt)
backup_header = disk->total_sectors - 1; backup_header = disk->total_sectors - 1;
grub_dprintf ("gpt", "backup GPT header relocated to 0x%llx\n", grub_dprintf ("gpt", "backup GPT header relocated to 0x%llx\n",
(unsigned long long) backup_header); (unsigned long long) backup_header);
gpt->primary.alternate_lba = grub_cpu_to_le64 (backup_header);
} }
grub_memcpy (&gpt->backup, &gpt->primary, sizeof (gpt->backup)); grub_memcpy (&gpt->backup, &gpt->primary, sizeof (gpt->backup));
gpt->backup.header_lba = gpt->primary.alternate_lba;
gpt->backup.alternate_lba = gpt->primary.header_lba;
gpt->backup.partitions = grub_cpu_to_le64 (backup_header -
grub_gpt_size_to_sectors (gpt, gpt->entries_size));
} }
else if (grub_gpt_backup_valid (gpt)) else if (grub_gpt_backup_valid (gpt))
{ {
grub_dprintf ("gpt", "backup GPT is valid\n"); grub_dprintf ("gpt", "backup GPT is valid\n");
backup_header = grub_le_to_cpu64 (gpt->backup.header_lba);
grub_memcpy (&gpt->primary, &gpt->backup, sizeof (gpt->primary)); grub_memcpy (&gpt->primary, &gpt->backup, sizeof (gpt->primary));
gpt->primary.header_lba = gpt->backup.alternate_lba;
gpt->primary.alternate_lba = gpt->backup.header_lba;
gpt->primary.partitions = grub_cpu_to_le64_compile_time (2);
} }
else else
return grub_error (GRUB_ERR_BUG, "No valid GPT"); return grub_error (GRUB_ERR_BUG, "No valid GPT");
backup_entries = backup_header -
grub_gpt_size_to_sectors (gpt, gpt->entries_size);
grub_dprintf ("gpt", "backup GPT entries will be located at 0x%llx\n",
(unsigned long long) backup_entries);
/* Update/fixup header and partition table locations. */
gpt->primary.header_lba = grub_cpu_to_le64_compile_time (1);
gpt->primary.alternate_lba = grub_cpu_to_le64 (backup_header);
gpt->primary.partitions = grub_cpu_to_le64_compile_time (2);
gpt->backup.header_lba = gpt->primary.alternate_lba;
gpt->backup.alternate_lba = gpt->primary.header_lba;
gpt->backup.partitions = grub_cpu_to_le64 (backup_entries);
/* Recompute checksums. */ /* Recompute checksums. */
if (grub_gpt_update_checksums (gpt)) if (grub_gpt_update_checksums (gpt))
return grub_errno; return grub_errno;