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lvm2/lib/label/label.c
Patrick Caulfield 8cdf0a831c Wipe the first label if writing the second one failed.
2001-12-18 14:39:32 +00:00

520 lines
12 KiB
C
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/*
* Copyright (C) 2001 Sistina Software
*
* This file is released under the LGPL.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include "device.h"
#include "dev-cache.h"
#include "log.h"
#include "filter.h"
#include "label.h"
#include "pool.h"
#include "xlate.h"
/* Label Magic is "LnXl" - error: imagination failure */
#define LABEL_MAGIC 0x6c586e4c
/* Size of blocks that dev_get_size() returns the number of */
#define BLOCK_SIZE 512
/* Our memory pool */
static void *label_pool = NULL;
/* This is just the "struct label" with the data pointer removed */
struct label_ondisk
{
uint32_t magic;
uint32_t crc;
uint64_t label1_loc;
uint64_t label2_loc;
uint16_t datalen;
uint16_t pad;
uint32_t version[3];
char disk_type[32];
};
struct filter_private
{
void *mem;
char disk_type[32];
uint32_t version[3];
int version_match;
};
/* Calculate CRC32 of a buffer */
static uint32_t crc32(uint32_t initial, const unsigned char *databuf, size_t datalen)
{
uint32_t idx, crc = initial;
static const u_int crctab[] = {
0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
};
for (idx = 0; idx < datalen; idx++) {
crc ^= *databuf++;
crc = (crc >> 4) ^ crctab[crc & 0xf];
crc = (crc >> 4) ^ crctab[crc & 0xf];
}
return crc;
}
/* 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;
}
/* Calculate the locations we should find the labels in */
static inline void get_label_locations(uint64_t size, uint32_t sectsize, long *first, long *second)
{
*first = sectsize;
*second = size*BLOCK_SIZE - sectsize;
}
/* Read a label off disk - the data area is allocated
from the pool in label->pool and should be freed by
the caller */
int label_read(struct device *dev, struct label *label)
{
uint64_t size;
uint32_t sectsize;
char *block;
struct label_ondisk *ondisk;
int status;
int iter;
long offset[2];
if (!dev_get_size(dev, &size))
return 0;
if (!dev_get_sectsize(dev, &sectsize))
return 0;
if (!dev_open(dev, O_RDONLY))
return 0;
if (label_pool == NULL)
label_pool = pool_create(BLOCK_SIZE);
block = pool_alloc(label_pool, sectsize);
if (!block)
{
stack;
return 0;
}
ondisk = (struct label_ondisk *)block;
get_label_locations(size, sectsize, &offset[0], &offset[1]);
/* If the first label is bad then use the second */
for (iter = 0; iter <= 1; iter++)
{
status = dev_read(dev, offset[iter], sectsize, block);
if (status)
{
struct label incore;
int i;
int found_nul;
/* If the MAGIC doesn't match there's no point in
carrying on */
if (xlate32(ondisk->magic) != LABEL_MAGIC)
continue;
/* Look for a NUL in the disk_type string so we don't
SEGV is something has gone horribly wrong */
found_nul = 0;
for (i=0; i<sizeof(ondisk->disk_type); i++)
if (ondisk->disk_type[i] == '\0')
found_nul = 1;
if (!found_nul)
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]);
incore.label1_loc = xlate64(ondisk->label1_loc);
incore.label2_loc = xlate64(ondisk->label2_loc);
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 Crc */
if (incore.crc != calc_crc(&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;
}
/* Check label locations match our view of the device */
if (incore.label1_loc != offset[0])
log_error("Label 1 location is wrong in label %d - check block size of the device\n",
iter);
if (incore.label2_loc != offset[1])
log_error("Label 2 location is wrong in label %d - the size of the device must have changed\n",
iter);
/* Copy to user's data area */
*label = incore;
label->data = pool_alloc(label_pool, incore.datalen);
if (!label->data)
{
stack;
return 0;
}
memcpy(label->data, incore.data, incore.datalen);
pool_free(label_pool, block);
dev_close(dev);
return 1;
}
}
pool_free(label_pool, block);
dev_close(dev);
return 0;
}
/* Write a label to a device */
int label_write(struct device *dev, struct label *label)
{
uint64_t size;
uint32_t sectsize;
char *block;
struct label_ondisk *ondisk;
int status1, status2;
long offset[2];
if (!dev_get_size(dev, &size))
return 0;
if (!dev_get_sectsize(dev, &sectsize))
return 0;
/* Can the metata fit in the remaining space ? */
if (label->datalen > sectsize - sizeof(struct label_ondisk))
return 0;
if (label_pool == NULL)
label_pool = pool_create(BLOCK_SIZE);
block = pool_alloc(label_pool, sizeof(struct label_ondisk) + label->datalen);
if (!block)
{
stack;
return 0;
}
ondisk = (struct label_ondisk *)block;
/* Make sure the label has the right magic number in it */
label->magic = LABEL_MAGIC;
label->label1_loc = offset[0];
label->label2_loc = offset[1];
get_label_locations(size, sectsize, &offset[0], &offset[1]);
/* 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]);
ondisk->label1_loc = xlate64(offset[0]);
ondisk->label2_loc = xlate64(offset[1]);
ondisk->datalen = xlate16(label->datalen);
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))
{
pool_free(label_pool, block);
return 0;
}
status1 = dev_write(dev, offset[0], sizeof(struct label_ondisk) + label->datalen, block);
if (!status1)
log_error("Error writing label 1\n");
/* Write another at the end of the device */
status2 = dev_write(dev, offset[1], sizeof(struct label_ondisk) + label->datalen, block);
if (!status2)
{
char zerobuf[sizeof(struct label_ondisk)];
log_error("Error writing label 2\n");
/* Wipe the first label so it doesn't get confusing */
memset(zerobuf, 0, sizeof(struct label_ondisk));
if (!dev_write(dev, offset[0], sizeof(struct label_ondisk), zerobuf))
log_error("Error erasing label 1\n");
}
pool_free(label_pool, block);
dev_close(dev);
return ((status1 != 0) && (status2 != 0));
}
/* Return 1 for Yes, 0 for No */
int is_labelled(struct device *dev)
{
struct label l;
int status;
status = label_read(dev, &l);
if (status) label_free(&l);
return status;
}
/* Check the device is labelled and has the right format_type */
static int _accept_format(struct dev_filter *f, struct device *dev)
{
struct label l;
int status;
struct filter_private *fp = (struct filter_private *) f->private;
status = label_read(dev, &l);
if (status) label_free(&l);
if (status)
{
if (strcmp(l.disk_type, fp->disk_type) == 0)
{
switch (fp->version_match)
{
case VERSION_MATCH_EQUAL:
if (l.version[0] == fp->version[0] &&
l.version[1] == fp->version[1] &&
l.version[2] == fp->version[2])
return 1;
break;
case VERSION_MATCH_LESSTHAN:
if (l.version[0] == fp->version[0] &&
l.version[1] < fp->version[1])
return 1;
break;
case VERSION_MATCH_LESSEQUAL:
if (l.version[0] == fp->version[0] &&
l.version[1] <= fp->version[1])
return 1;
break;
case VERSION_MATCH_ANY:
return 1;
}
}
}
return 0;
}
/* We just want to know if it's labelled or not */
static int _accept_label(struct dev_filter *f, struct device *dev)
{
return is_labelled(dev);
}
static void _destroy(struct dev_filter *f)
{
struct filter_private *fp = (struct filter_private *) f->private;
pool_destroy(fp->mem);
}
/* A filter to find devices with a particular label type on them */
struct dev_filter *label_format_filter_create(char *disk_type, uint32_t version[3], int match_type)
{
struct pool *mem;
struct filter_private *fp;
struct dev_filter *f;
/* Validate the match type */
if (match_type != VERSION_MATCH_EQUAL &&
match_type != VERSION_MATCH_LESSTHAN &&
match_type != VERSION_MATCH_LESSEQUAL &&
match_type != VERSION_MATCH_ANY)
return 0;
mem = pool_create(10 * 1024);
if (!mem) {
stack;
return NULL;
}
if (!(f = pool_zalloc(mem, sizeof(*f)))) {
stack;
goto bad;
}
if (!(fp = pool_zalloc(mem, sizeof(*fp)))) {
stack;
goto bad;
}
fp->mem = mem;
strcpy(fp->disk_type, disk_type);
fp->version[0] = version[0];
fp->version[1] = version[1];
fp->version[2] = version[2];
fp->version_match = match_type;
f->passes_filter = _accept_format;
f->destroy = _destroy;
f->private = fp;
return f;
bad:
pool_destroy(mem);
return NULL;
}
/* A filter to find devices with any label on them */
struct dev_filter *label_filter_create()
{
struct pool *mem = pool_create(10 * 1024);
struct filter_private *fp;
struct dev_filter *f;
if (!mem) {
stack;
return NULL;
}
if (!(f = pool_zalloc(mem, sizeof(*f)))) {
stack;
goto bad;
}
if (!(fp = pool_zalloc(mem, sizeof(*fp)))) {
stack;
goto bad;
}
fp->mem = mem;
f->passes_filter = _accept_label;
f->destroy = _destroy;
f->private = fp;
return f;
bad:
pool_destroy(mem);
return NULL;
}
/* Return 1 if both labels are identical, 0 if not or there was an error */
int labels_match(struct device *dev)
{
uint64_t size;
uint32_t sectsize;
char *block1;
char *block2;
struct label_ondisk *ondisk1;
struct label_ondisk *ondisk2;
int status = 0;
long offset[2];
if (!dev_get_size(dev, &size))
return 0;
if (!dev_get_sectsize(dev, &sectsize))
return 0;
if (label_pool == NULL)
label_pool = pool_create(BLOCK_SIZE);
/* Allocate some space for the blocks we are going to read in */
block1 = pool_alloc(label_pool, sectsize);
if (!block1)
{
stack;
return 0;
}
block2 = pool_alloc(label_pool, sectsize);
if (!block2)
{
stack;
pool_free(label_pool, block1);
return 0;
}
ondisk1 = (struct label_ondisk *)block1;
ondisk2 = (struct label_ondisk *)block2;
get_label_locations(size, sectsize, &offset[0], &offset[1]);
/* Fetch em */
if (!dev_open(dev, O_RDONLY))
goto finish;
if (!dev_read(dev, offset[0], sectsize, block1))
goto finish;
if (!dev_read(dev, offset[1], sectsize, block2))
goto finish;
dev_close(dev);
/* Is it labelled? */
if (xlate32(ondisk1->magic) != LABEL_MAGIC)
goto finish;
/* Compare the whole structs */
if (memcmp(ondisk1, ondisk2, sizeof(struct label_ondisk)) != 0)
goto finish;
/* OK, check the data area */
if (memcmp(block1 + sizeof(struct label_ondisk),
block2 + sizeof(struct label_ondisk),
xlate16(ondisk1->datalen)) != 0)
goto finish;
/* They match !! */
status = 1;
finish:
pool_free(label_pool, block2);
pool_free(label_pool, block1);
return status;
}
/* Free data area allocated by label_read() */
void label_free(struct label *label)
{
if (label->data)
pool_free(label_pool, label->data);
}
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