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Use a proper CRC calculation.

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This commit is contained in:
Patrick Caulfield 2001-12-12 09:05:44 +00:00
parent f4a7ce7c49
commit 8a51c23765
2 changed files with 50 additions and 36 deletions
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84
lib/label/label.c
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@ -28,11 +28,12 @@ static void *label_pool = NULL;
struct label_ondisk
{
uint32_t magic;
uint32_t checksum;
uint32_t crc;
uint16_t datalen;
uint16_t pad;
char disk_type[32];
uint32_t version[3];
char disk_type[32];
};
struct filter_private
@ -44,29 +45,45 @@ struct filter_private
};
/* Calculate checksum */
static uint32_t calc_checksum(struct label *label)
/* CRC32 code taken from Linux kernel */
static int crc32( int initial, char * s, int length )
{
uint32_t csum = 0;
int i;
/* indices */
int perByte;
int perBit;
csum += label->magic;
csum += label->version[0];
csum += label->version[1];
csum += label->version[2];
csum += label->datalen;
/* crc polynomial for Ethernet */
const unsigned long poly = 0xedb88320;
for (i=0; i<label->datalen; i++)
{
csum += label->data[i];
}
/* crc value - carry over */
unsigned long crc_value = initial;
for (i=0; i<strlen(label->disk_type); i++)
{
csum += label->disk_type[i];
}
for ( perByte = 0; perByte < length; perByte ++ ) {
unsigned char c;
return csum;
c = *(s++);
for ( perBit = 0; perBit < 8; perBit++ ) {
crc_value = (crc_value>>1)^
(((crc_value^c)&0x01)?poly:0);
c >>= 1;
}
}
return crc_value;
}
/* Calculate crc */
static uint32_t calc_crc(struct label *label)
{
uint32_t crcval = 0xffffffff;
crcval = crc32(crcval, (char *)&label->magic, sizeof(label->magic));
crcval = crc32(crcval, (char *)&label->datalen, sizeof(label->datalen));
crcval = crc32(crcval, (char *)label->disk_type, strlen(label->disk_type));
crcval = crc32(crcval, (char *)&label->version, sizeof(label->version));
crcval = crc32(crcval, (char *)label->data, label->datalen);
return crcval;
}
/* Read a label off disk - the data area is allocated
@ -131,25 +148,24 @@ int label_read(struct device *dev, struct label *label)
continue;
/* Copy and convert endianness */
strncpy(incore.disk_type, ondisk->disk_type, sizeof(incore.disk_type));
incore.magic = xlate32(ondisk->magic);
incore.version[0] = xlate32(ondisk->version[0]);
incore.version[1] = xlate32(ondisk->version[1]);
incore.version[2] = xlate32(ondisk->version[2]);
for (i=0; i<strlen(ondisk->disk_type)+1; i++)
incore.disk_type[i] = ondisk->disk_type[i];
incore.checksum = xlate32(ondisk->checksum);
incore.datalen = xlate16(ondisk->datalen);
incore.data = block + sizeof(struct label_ondisk);
incore.crc = xlate32(ondisk->crc);
/* Make sure datalen is a sensible size too */
if (incore.datalen > sectsize)
continue;
/* Check Checksum */
if (incore.checksum != calc_checksum(&incore))
/* Check Crc */
if (incore.crc != calc_crc(&incore))
{
log_error("Checksum %d on device %s does not match. got %x, expected %x",
iter, dev_name(dev), incore.checksum, calc_checksum(&incore));
log_error("Crc %d on device %s does not match. got %x, expected %x",
iter, dev_name(dev), incore.crc, calc_crc(&incore));
continue;
}
@ -183,7 +199,6 @@ int label_write(struct device *dev, struct label *label)
char *block;
struct label_ondisk *ondisk;
int status1, status2;
int i;
if (!dev_get_size(dev, &size))
return 0;
@ -204,21 +219,20 @@ int label_write(struct device *dev, struct label *label)
stack;
return 0;
}
ondisk = (struct label_ondisk *)block;
/* Make into ondisk format */
/* Make sure the label has the right magic number in it */
label->magic = LABEL_MAGIC;
ondisk->magic = xlate32(LABEL_MAGIC);
/* Make into ondisk format */
ondisk->magic = xlate32(LABEL_MAGIC);
ondisk->version[0] = xlate32(label->version[0]);
ondisk->version[1] = xlate32(label->version[1]);
ondisk->version[2] = xlate32(label->version[2]);
for (i=0; i<strlen(label->disk_type)+1; i++)
ondisk->disk_type[i] = label->disk_type[i];
ondisk->datalen = xlate16(label->datalen);
ondisk->checksum = xlate32(calc_checksum(label));
strncpy(ondisk->disk_type, label->disk_type, sizeof(ondisk->disk_type));
memcpy(block+sizeof(struct label_ondisk), label->data, label->datalen);
ondisk->crc = xlate32(calc_crc(label));
/* Write metadata to disk */
if (!dev_open(dev, O_RDWR))
@ -408,7 +422,7 @@ int labels_match(struct device *dev)
if (label_pool == NULL)
label_pool = pool_create(512);
/* ALlocate some space for the blocks we are going to read in */
/* Allocate some space for the blocks we are going to read in */
block1 = pool_alloc(label_pool, sectsize);
if (!block1)
{

2
lib/label/label.h
View File

@ -7,7 +7,7 @@
struct label
{
uint32_t magic;
uint32_t checksum;
uint32_t crc;
uint16_t datalen;
char disk_type[32];