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gpt: consolidate crc32 computation code

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The gcrypt API is overly verbose, wrap it up in a helper function to
keep this rather common operation easy to use.
This commit is contained in:
Michael Marineau 2014-10-18 18:18:17 -07:00
parent 4dd009a6fb
commit dc6076187e
1 changed files with 24 additions and 19 deletions
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43
grub-core/lib/gpt.c
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@ -32,22 +32,17 @@ static grub_uint8_t grub_gpt_magic[] = GRUB_GPT_HEADER_MAGIC;
static grub_err_t static grub_err_t
grub_gpt_header_crc32 (struct grub_gpt_header *gpt, grub_uint32_t *crc) grub_gpt_lecrc32 (void *data, grub_size_t len, grub_uint32_t *crc)
{ {
grub_uint8_t *crc32_context; grub_uint8_t *crc32_context;
grub_uint32_t old;
crc32_context = grub_zalloc (GRUB_MD_CRC32->contextsize); crc32_context = grub_zalloc (GRUB_MD_CRC32->contextsize);
if (!crc32_context) if (!crc32_context)
return grub_errno; return grub_errno;
/* crc32 must be computed with the field cleared. */
old = gpt->crc32;
gpt->crc32 = 0;
GRUB_MD_CRC32->init (crc32_context); GRUB_MD_CRC32->init (crc32_context);
GRUB_MD_CRC32->write (crc32_context, gpt, sizeof (*gpt)); GRUB_MD_CRC32->write (crc32_context, data, len);
GRUB_MD_CRC32->final (crc32_context); GRUB_MD_CRC32->final (crc32_context);
gpt->crc32 = old;
/* GRUB_MD_CRC32 always uses big endian, gpt is always little. */ /* GRUB_MD_CRC32 always uses big endian, gpt is always little. */
*crc = grub_swap_bytes32 (*(grub_uint32_t *) *crc = grub_swap_bytes32 (*(grub_uint32_t *)
@ -58,6 +53,25 @@ grub_gpt_header_crc32 (struct grub_gpt_header *gpt, grub_uint32_t *crc)
return GRUB_ERR_NONE; return GRUB_ERR_NONE;
} }
static grub_err_t
grub_gpt_header_lecrc32 (struct grub_gpt_header *header, grub_uint32_t *crc)
{
grub_uint32_t old, new;
grub_err_t err;
/* crc32 must be computed with the field cleared. */
old = header->crc32;
header->crc32 = 0;
err = grub_gpt_lecrc32 (header, sizeof (*header), &new);
header->crc32 = old;
if (err)
return err;
*crc = new;
return GRUB_ERR_NONE;
}
/* Make sure the MBR is a protective MBR and not a normal MBR. */ /* Make sure the MBR is a protective MBR and not a normal MBR. */
grub_err_t grub_err_t
grub_gpt_pmbr_check (struct grub_msdos_partition_mbr *mbr) grub_gpt_pmbr_check (struct grub_msdos_partition_mbr *mbr)
@ -87,7 +101,7 @@ grub_gpt_header_check (struct grub_gpt_header *gpt,
if (gpt->version != GRUB_GPT_HEADER_VERSION) if (gpt->version != GRUB_GPT_HEADER_VERSION)
return grub_error (GRUB_ERR_BAD_PART_TABLE, "unknown GPT version"); return grub_error (GRUB_ERR_BAD_PART_TABLE, "unknown GPT version");
if (grub_gpt_header_crc32 (gpt, &crc)) if (grub_gpt_header_lecrc32 (gpt, &crc))
return grub_errno; return grub_errno;
if (gpt->crc32 != crc) if (gpt->crc32 != crc)
@ -158,7 +172,6 @@ grub_gpt_read_entries (grub_disk_t disk, grub_gpt_t gpt,
struct grub_gpt_header *header) struct grub_gpt_header *header)
{ {
struct grub_gpt_partentry *entries = NULL; struct grub_gpt_partentry *entries = NULL;
grub_uint8_t *crc32_context = NULL;
grub_uint32_t count, size, crc; grub_uint32_t count, size, crc;
grub_disk_addr_t addr; grub_disk_addr_t addr;
grub_size_t entries_size; grub_size_t entries_size;
@ -185,22 +198,15 @@ grub_gpt_read_entries (grub_disk_t disk, grub_gpt_t gpt,
if (grub_disk_read (disk, addr, 0, entries_size, entries)) if (grub_disk_read (disk, addr, 0, entries_size, entries))
goto fail; goto fail;
crc32_context = grub_zalloc (GRUB_MD_CRC32->contextsize); if (grub_gpt_lecrc32 (entries, entries_size, &crc))
if (!crc32_context)
goto fail; goto fail;
GRUB_MD_CRC32->init (crc32_context); if (crc != header->partentry_crc32)
GRUB_MD_CRC32->write (crc32_context, entries, entries_size);
GRUB_MD_CRC32->final (crc32_context);
crc = *(grub_uint32_t *) GRUB_MD_CRC32->read (crc32_context);
if (grub_swap_bytes32 (crc) != header->partentry_crc32)
{ {
grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid GPT entry crc32"); grub_error (GRUB_ERR_BAD_PART_TABLE, "invalid GPT entry crc32");
goto fail; goto fail;
} }
grub_free (crc32_context);
grub_free (gpt->entries); grub_free (gpt->entries);
gpt->entries = entries; gpt->entries = entries;
gpt->entries_size = entries_size; gpt->entries_size = entries_size;
@ -208,7 +214,6 @@ grub_gpt_read_entries (grub_disk_t disk, grub_gpt_t gpt,
fail: fail:
grub_free (entries); grub_free (entries);
grub_free (crc32_context);
return grub_errno; return grub_errno;
} }