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/*
* ks_index.c
* ----------
* Keystore index API. This is internal within libhal.
*
* Copyright (c) 2016, NORDUnet A/S All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <string.h>
#include <assert.h>
#include "hal.h"
#include "hal_internal.h"
/*
* Return value indicates whether the name is present in the index.
* "where" indicates the name's position whether present or not.
*
* NB: this does NOT return a block number, it returns an index into
* ksi->index[].
*/
static int ks_find(const hal_ks_index_t * const ksi,
const hal_uuid_t * const name,
int *where)
{
assert(ksi != NULL && ksi->index != NULL && ksi->names != NULL && name != NULL && where != NULL);
int lo = -1;
int hi = ksi->used;
for (;;) {
int m = (lo + hi) / 2;
if (hi == 0 || m == lo) {
*where = hi;
return 0;
}
const int cmp = hal_uuid_cmp(name, &ksi->names[ksi->index[m]]);
if (cmp < 0)
hi = m;
else if (cmp > 0)
lo = m;
else {
*where = m;
return 1;
}
}
}
/*
* Heapsort the index. We only need to do this on setup, for other
* operations we're just inserting or deleting a single entry in an
* already-ordered array, which is just a search problem. If we were
* really crunched for space, we could use an insertion sort here, but
* heapsort is easy and works well with data already in place.
*/
static inline void ks_heapsift(hal_ks_index_t *ksi, int parent, const int end)
{
assert(ksi != NULL && ksi->index != NULL && ksi->names != NULL &&
parent >= 0 && end >= parent);
for (;;) {
const int left_child = parent * 2 + 1;
const int right_child = parent * 2 + 2;
int biggest = parent;
if (left_child <= end && hal_uuid_cmp(&ksi->names[ksi->index[biggest]],
&ksi->names[ksi->index[left_child]]) < 0)
biggest = left_child;
if (right_child <= end && hal_uuid_cmp(&ksi->names[ksi->index[biggest]],
&ksi->names[ksi->index[right_child]]) < 0)
biggest = right_child;
if (biggest == parent)
return;
const uint16_t tmp = ksi->index[biggest];
ksi->index[biggest] = ksi->index[parent];
ksi->index[parent] = tmp;
parent = biggest;
}
}
static inline void ks_heapsort(hal_ks_index_t *ksi)
{
assert(ksi != NULL && ksi->index != NULL && ksi->names != NULL);
if (ksi->used < 2)
return;
for (int i = (ksi->used - 2) / 2; i >= 0; i--)
ks_heapsift(ksi, i, ksi->used - 1);
for (int i = ksi->used - 1; i > 0; i--) {
const uint16_t tmp = ksi->index[i];
ksi->index[i] = ksi->index[0];
ksi->index[0] = tmp;
ks_heapsift(ksi, 0, i);
}
}
hal_error_t hal_ks_index_setup(hal_ks_index_t *ksi)
{
if (ksi == NULL || ksi->index == NULL || ksi->names == NULL ||
ksi->size == 0 || ksi->used > ksi->size)
return HAL_ERROR_BAD_ARGUMENTS;
/*
* Only setup task we have at the moment is sorting the index.
*/
ks_heapsort(ksi);
return HAL_OK;
}
hal_error_t hal_ks_index_find(hal_ks_index_t *ksi,
const hal_uuid_t * const name,
unsigned *blockno)
{
if (ksi == NULL || ksi->index == NULL || ksi->names == NULL ||
ksi->size == 0 || ksi->used > ksi->size || name == NULL)
return HAL_ERROR_BAD_ARGUMENTS;
int where;
if (!ks_find(ksi, name, &where))
return HAL_ERROR_KEY_NOT_FOUND;
if (blockno != NULL)
*blockno = ksi->index[where];
return HAL_OK;
}
hal_error_t hal_ks_index_add(hal_ks_index_t *ksi,
const hal_uuid_t * const name,
unsigned *blockno)
{
if (ksi == NULL || ksi->index == NULL || ksi->names == NULL ||
ksi->size == 0 || ksi->used > ksi->size || name == NULL)
return HAL_ERROR_BAD_ARGUMENTS;
if (ksi->used == ksi->size)
return HAL_ERROR_NO_KEY_SLOTS_AVAILABLE;
int where;
if (ks_find(ksi, name, &where))
return HAL_ERROR_KEY_NAME_IN_USE;
/*
* Grab first block on free list, which makes room to slide the
* index down by one slot so we can insert the new block number.
*/
const size_t len = (ksi->used - where) * sizeof(*ksi->index);
const uint16_t b = ksi->index[ksi->used++];
memmove(&ksi->index[where + 1], &ksi->index[where], len);
ksi->index[where] = b;
ksi->names[b] = *name;
if (blockno != NULL)
*blockno = b;
return HAL_OK;
}
hal_error_t hal_ks_index_delete(hal_ks_index_t *ksi,
const hal_uuid_t * const name,
unsigned *blockno)
{
if (ksi == NULL || ksi->index == NULL || ksi->names == NULL ||
ksi->size == 0 || ksi->used > ksi->size || name == NULL)
return HAL_ERROR_BAD_ARGUMENTS;
int where;
if (ksi->used == 0 || !ks_find(ksi, name, &where))
return HAL_ERROR_KEY_NOT_FOUND;
/*
* Free the block and stuff it at the end of the free list.
*/
const size_t len = (ksi->size - where - 1) * sizeof(*ksi->index);
const uint16_t b = ksi->index[where];
memmove(&ksi->index[where], &ksi->index[where + 1], len);
ksi->index[ksi->size - 1] = b;
ksi->used--;
memset(&ksi->names[b], 0, sizeof(ksi->names[b]));
if (blockno != NULL)
*blockno = b;
return HAL_OK;
}
/*
* Might want a hal_ks_index_replace(), which would be an efficiency
* hack replacement (roughly 2x) for a delete followed by an add with
* the same name. Implementation would be to find the old existing
* block, pull the first block off the free list, sliding the free
* list down, drop the new block in instead of the old, put the old
* block at the end of the free list, and return the new block.
*/
/*
* Local variables:
* indent-tabs-mode: nil
* End:
*/
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