/*
* Construct and return the list of xattr name:value pairs for the passed xattr
* id
*
* There are two users for get_xattr(), Mksquashfs uses it to read the
* xattrs from the filesystem on appending, and Unsquashfs uses it
* to retrieve the xattrs for writing to disk.
*
* Unfortunately, the two users disagree on what to do with unknown
* xattr prefixes, Mksquashfs wants to treat this as fatal otherwise
* this will cause xattrs to be be lost on appending. Unsquashfs
* on the otherhand wants to retrieve the xattrs which are known and
* to ignore the rest, this allows Unsquashfs to cope more gracefully
* with future versions which may have unknown xattrs, as long as the
* general xattr structure is adhered to, Unsquashfs should be able
* to safely ignore unknown xattrs, and to write the ones it knows about,
* this is better than completely refusing to retrieve all the xattrs.
*
* If ignore is TRUE then don't treat unknown xattr prefixes as
* a failure to read the xattr.
*/
struct xattr_list *get_xattr(int i, unsigned int *count, int ignore) {
long long start;
struct xattr_list *xattr_list = NULL;
unsigned int offset;
void *xptr;
int j = 0, res = 1;
TRACE("get_xattr\n");
*count = xattr_ids[i].count;
start = SQUASHFS_XATTR_BLK(xattr_ids[i].xattr) + xattr_table_start;
offset = SQUASHFS_XATTR_OFFSET(xattr_ids[i].xattr);
xptr = xattrs + get_xattr_block(start) + offset;
TRACE("get_xattr: xattr_id %d, count %d, start %lld, offset %d\n", i, *count, start, offset);
while (j < *count) {
struct squashfs_xattr_entry entry;
struct squashfs_xattr_val val;
if (res != 0) {
xattr_list = realloc(xattr_list, (j + 1) * sizeof(struct xattr_list));
if (xattr_list == NULL)
MEM_ERROR();
}
SQUASHFS_SWAP_XATTR_ENTRY(xptr, &entry);
xptr += sizeof(entry);
res = read_xattr_entry(&xattr_list[j], &entry, xptr);
if (ignore && res == 0) {
/* unknown prefix, but ignore flag is set */
(*count)--;
continue;
}
if (res != 1)
goto failed;
xptr += entry.size;
TRACE("get_xattr: xattr %d, type %d, size %d, name %s\n", j, entry.type, entry.size, xattr_list[j].full_name);
if (entry.type & SQUASHFS_XATTR_VALUE_OOL) {
long long xattr;
void *ool_xptr;
xptr += sizeof(val);
SQUASHFS_SWAP_LONG_LONGS(xptr, &xattr, 1);
xptr += sizeof(xattr);
start = SQUASHFS_XATTR_BLK(xattr) + xattr_table_start;
offset = SQUASHFS_XATTR_OFFSET(xattr);
ool_xptr = xattrs + get_xattr_block(start) + offset;
SQUASHFS_SWAP_XATTR_VAL(ool_xptr, &val);
xattr_list[j].value = ool_xptr + sizeof(val);
} else {
SQUASHFS_SWAP_XATTR_VAL(xptr, &val);
xattr_list[j].value = xptr + sizeof(val);
xptr += sizeof(val) + val.vsize;
}
TRACE("get_xattr: xattr %d, vsize %d\n", j, val.vsize);
xattr_list[j++].vsize = val.vsize;
}
if (*count == 0)
goto failed;
return xattr_list;
failed:
free_xattr(xattr_list, j);
return NULL;
}
int generate_xattrs(int xattrs, struct xattr_list *xattr_list)
{
int total_size, i;
int xattr_value_max;
void *xp;
long long xattr_disk;
struct dupl_id *xattr_dupl;
/*
* check if the file xattrs are a complete duplicate of a pre-existing
* id
*/
xattr_dupl = check_id_dupl(xattr_list, xattrs);
if (xattr_dupl == NULL)
return SQUASHFS_INVALID_XATTR;
if(xattr_dupl->xattr_id != SQUASHFS_INVALID_XATTR)
return xattr_dupl->xattr_id;
/*
* Scan the xattr_list deciding which type to assign to each
* xattr. The choice is fairly straightforward, and depends on the
* size of each xattr name/value and the overall size of the
* resultant xattr list stored in the xattr metadata table.
*
* Choices are whether to store data inline or out of line.
*
* The overall goal is to optimise xattr scanning and lookup, and
* to enable the file system layout to scale from a couple of
* small xattr name/values to a large number of large xattr
* names/values without affecting performance. While hopefully
* enabling the common case of a couple of small xattr name/values
* to be stored efficiently
*
* Code repeatedly scans, doing the following
* move xattr data out of line if it exceeds
* xattr_value_max. Where xattr_value_max is
* initially XATTR_INLINE_MAX. If the final uncompressed
* xattr list is larger than XATTR_TARGET_MAX then more
* aggressively move xattr data out of line by repeatedly
* setting inline threshold to 1/2, then 1/4, 1/8 of
* XATTR_INLINE_MAX until target achieved or there's
* nothing left to move out of line
*/
xattr_value_max = XATTR_INLINE_MAX;
while(1) {
for(total_size = 0, i = 0; i < xattrs; i++) {
struct xattr_list *xattr = &xattr_list[i];
xattr->type &= XATTR_PREFIX_MASK; /* all inline */
if (xattr->vsize > xattr_value_max)
xattr->type |= XATTR_VALUE_OOL;
total_size += get_xattr_size(xattr);
}
/*
* If the total size of the uncompressed xattr list is <=
* XATTR_TARGET_MAX we're done
*/
if(total_size <= XATTR_TARGET_MAX)
break;
if(xattr_value_max == XATTR_VALUE_OOL_SIZE)
break;
/*
* Inline target not yet at minimum and so reduce it, and
* try again
*/
xattr_value_max /= 2;
if(xattr_value_max < XATTR_VALUE_OOL_SIZE)
xattr_value_max = XATTR_VALUE_OOL_SIZE;
}
/*
* Check xattr values for duplicates
*/
for(i = 0; i < xattrs; i++) {
check_value_dupl(&xattr_list[i]);
}
/*
* Add each out of line value to the file system xattr table
* if it doesn't already exist as a duplicate
*/
for(i = 0; i < xattrs; i++) {
struct xattr_list *xattr = &xattr_list[i];
if((xattr->type & XATTR_VALUE_OOL) &&
(xattr->ool_value == SQUASHFS_INVALID_BLK)) {
struct squashfs_xattr_val val;
int size = sizeof(val) + xattr->vsize;
xp = get_xattr_space(size, &xattr->ool_value);
val.vsize = xattr->vsize;
SQUASHFS_SWAP_XATTR_VAL(&val, xp);
memcpy(xp + sizeof(val), xattr->value, xattr->vsize);
}
}
/*
* Create xattr list and add to file system xattr table
*/
get_xattr_space(0, &xattr_disk);
for(i = 0; i < xattrs; i++) {
struct xattr_list *xattr = &xattr_list[i];
struct squashfs_xattr_entry entry;
struct squashfs_xattr_val val;
xp = get_xattr_space(sizeof(entry) + xattr->size, NULL);
entry.type = xattr->type;
entry.size = xattr->size;
SQUASHFS_SWAP_XATTR_ENTRY(&entry, xp);
memcpy(xp + sizeof(entry), xattr->name, xattr->size);
if(xattr->type & XATTR_VALUE_OOL) {
int size = sizeof(val) + XATTR_VALUE_OOL_SIZE;
xp = get_xattr_space(size, NULL);
val.vsize = XATTR_VALUE_OOL_SIZE;
SQUASHFS_SWAP_XATTR_VAL(&val, xp);
SQUASHFS_SWAP_LONG_LONGS(&xattr->ool_value, xp +
sizeof(val), 1);
} else {
int size = sizeof(val) + xattr->vsize;
xp = get_xattr_space(size, &xattr->ool_value);
val.vsize = xattr->vsize;
SQUASHFS_SWAP_XATTR_VAL(&val, xp);
memcpy(xp + sizeof(val), xattr->value, xattr->vsize);
}
}
/*
* Add to xattr id lookup table
*/
return get_xattr_id(xattrs, xattr_list, xattr_disk, xattr_dupl);
}
/*
* Construct and return the list of xattr name:value pairs for the passed xattr
* id
*/
struct xattr_list *get_xattr(int i, unsigned int *count)
{
long long start;
struct xattr_list *xattr_list = NULL;
unsigned int offset;
void *xptr;
int j;
TRACE("get_xattr\n");
*count = xattr_ids[i].count;
start = SQUASHFS_XATTR_BLK(xattr_ids[i].xattr) + xattr_table_start;
offset = SQUASHFS_XATTR_OFFSET(xattr_ids[i].xattr);
xptr = xattrs + get_xattr_block(start) + offset;
TRACE("get_xattr: xattr_id %d, count %d, start %lld, offset %d\n", i,
*count, start, offset);
for(j = 0; j < *count; j++) {
struct squashfs_xattr_entry entry;
struct squashfs_xattr_val val;
int res;
xattr_list = realloc(xattr_list, (j + 1) *
sizeof(struct xattr_list));
if(xattr_list == NULL) {
ERROR("Out of memory in get_xattrs\n");
goto failed;
}
SQUASHFS_SWAP_XATTR_ENTRY(&entry, xptr);
xptr += sizeof(entry);
res = read_xattr_entry(&xattr_list[j], &entry, xptr);
if(res != 1)
goto failed;
xptr += entry.size;
TRACE("get_xattr: xattr %d, type %d, size %d, name %s\n", j,
entry.type, entry.size, xattr_list[j].full_name);
if(entry.type & SQUASHFS_XATTR_VALUE_OOL) {
long long xattr;
void *ool_xptr;
xptr += sizeof(val);
SQUASHFS_SWAP_LONG_LONGS(&xattr, xptr, 1);
xptr += sizeof(xattr);
start = SQUASHFS_XATTR_BLK(xattr) + xattr_table_start;
offset = SQUASHFS_XATTR_OFFSET(xattr);
ool_xptr = xattrs + get_xattr_block(start) + offset;
SQUASHFS_SWAP_XATTR_VAL(&val, ool_xptr);
xattr_list[j].value = ool_xptr + sizeof(val);
} else {
SQUASHFS_SWAP_XATTR_VAL(&val, xptr);
xattr_list[j].value = xptr + sizeof(val);
xptr += sizeof(val) + val.vsize;
}
TRACE("get_xattr: xattr %d, vsize %d\n", j, val.vsize);
xattr_list[j].vsize = val.vsize;
}
return xattr_list;
failed:
free(xattr_list);
return NULL;
}
