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/*
Unix SMB/CIFS implementation.
Database interface wrapper around red-black trees
Copyright (C) Volker Lendecke 2007, 2008
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "rbtree.h"
#define DBWRAP_RBT_ALIGN(_size_) (((_size_)+15)&~15)
struct db_rbt_ctx {
struct rb_root tree;
};
struct db_rbt_rec {
struct db_rbt_ctx *db_ctx;
struct db_rbt_node *node;
};
/* The structure that ends up in the tree */
struct db_rbt_node {
struct rb_node rb_node;
size_t keysize, valuesize;
/*
* key and value are appended implicitly, "data" is only here as a
* target for offsetof()
*/
char data[1];
};
/*
* Hide the ugly pointer calculations in a function
*/
static struct db_rbt_node *db_rbt2node(struct rb_node *node)
{
return (struct db_rbt_node *)
((char *)node - offsetof(struct db_rbt_node, rb_node));
}
/*
* Compare two keys
*/
static int db_rbt_compare(TDB_DATA a, TDB_DATA b)
{
int res;
res = memcmp(a.dptr, b.dptr, MIN(a.dsize, b.dsize));
if ((res < 0) || ((res == 0) && (a.dsize < b.dsize))) {
return -1;
}
if ((res > 0) || ((res == 0) && (a.dsize > b.dsize))) {
return 1;
}
return 0;
}
/*
* dissect a db_rbt_node into its implicit key and value parts
*/
static void db_rbt_parse_node(struct db_rbt_node *node,
TDB_DATA *key, TDB_DATA *value)
{
key->dptr = ((uint8 *)node) + offsetof(struct db_rbt_node, data);
key->dsize = node->keysize;
value->dptr = key->dptr + node->keysize;
value->dsize = node->valuesize;
}
static NTSTATUS db_rbt_store(struct db_record *rec, TDB_DATA data, int flag)
{
struct db_rbt_rec *rec_priv = (struct db_rbt_rec *)rec->private_data;
struct db_rbt_node *node;
struct rb_node ** p;
struct rb_node * parent;
TDB_DATA this_key, this_val;
if (rec_priv->node != NULL) {
/*
* The record was around previously
*/
db_rbt_parse_node(rec_priv->node, &this_key, &this_val);
SMB_ASSERT(this_key.dsize == rec->key.dsize);
SMB_ASSERT(memcmp(this_key.dptr, rec->key.dptr,
this_key.dsize) == 0);
if (this_val.dsize >= data.dsize) {
/*
* The new value fits into the old space
*/
memcpy(this_val.dptr, data.dptr, data.dsize);
rec_priv->node->valuesize = data.dsize;
return NT_STATUS_OK;
}
/*
* We need to delete the key from the tree and start fresh,
* there's not enough space in the existing record
*/
rb_erase(&rec_priv->node->rb_node, &rec_priv->db_ctx->tree);
/*
* Keep the existing node around for a while: If the record
* existed before, we reference the key data in there.
*/
}
node = (struct db_rbt_node *)SMB_MALLOC(
offsetof(struct db_rbt_node, data) + rec->key.dsize
+ data.dsize);
if (node == NULL) {
SAFE_FREE(rec_priv->node);
return NT_STATUS_NO_MEMORY;
}
ZERO_STRUCT(node->rb_node);
node->keysize = rec->key.dsize;
node->valuesize = data.dsize;
db_rbt_parse_node(node, &this_key, &this_val);
memcpy(this_key.dptr, rec->key.dptr, node->keysize);
SAFE_FREE(rec_priv->node);
memcpy(this_val.dptr, data.dptr, node->valuesize);
parent = NULL;
p = &rec_priv->db_ctx->tree.rb_node;
while (*p) {
struct db_rbt_node *r;
TDB_DATA search_key, search_val;
int res;
parent = (*p);
r = db_rbt2node(*p);
db_rbt_parse_node(r, &search_key, &search_val);
res = db_rbt_compare(this_key, search_key);
if (res == -1) {
p = &(*p)->rb_left;
}
else if (res == 1) {
p = &(*p)->rb_right;
}
else {
smb_panic("someone messed with the tree");
}
}
rb_link_node(&node->rb_node, parent, p);
rb_insert_color(&node->rb_node, &rec_priv->db_ctx->tree);
return NT_STATUS_OK;
}
static NTSTATUS db_rbt_delete(struct db_record *rec)
{
struct db_rbt_rec *rec_priv = (struct db_rbt_rec *)rec->private_data;
if (rec_priv->node == NULL) {
return NT_STATUS_OK;
}
rb_erase(&rec_priv->node->rb_node, &rec_priv->db_ctx->tree);
SAFE_FREE(rec_priv->node);
return NT_STATUS_OK;
}
static struct db_record *db_rbt_fetch_locked(struct db_context *db_ctx,
TALLOC_CTX *mem_ctx,
TDB_DATA key)
{
struct db_rbt_ctx *ctx = talloc_get_type_abort(
db_ctx->private_data, struct db_rbt_ctx);
struct db_rbt_rec *rec_priv;
struct db_record *result;
struct rb_node *n;
size_t size;
bool found = false;
struct db_rbt_node *r = NULL;
TDB_DATA search_key = tdb_null, search_val = tdb_null;
n = ctx->tree.rb_node;
while (n != NULL) {
int res;
r = db_rbt2node(n);
db_rbt_parse_node(r, &search_key, &search_val);
res = db_rbt_compare(key, search_key);
if (res == -1) {
n = n->rb_left;
}
else if (res == 1) {
n = n->rb_right;
}
else {
found = true;
break;
}
}
/*
* In this low-level routine, play tricks to reduce the number of
* tallocs to one. Not recommened for general use, but here it pays
* off.
*/
size = DBWRAP_RBT_ALIGN(sizeof(struct db_record))
+ sizeof(struct db_rbt_rec);
if (!found) {
/*
* We need to keep the key around for later store
*/
size += key.dsize;
}
result = (struct db_record *)talloc_size(mem_ctx, size);
if (result == NULL) {
return NULL;
}
rec_priv = (struct db_rbt_rec *)
((char *)result + DBWRAP_RBT_ALIGN(sizeof(struct db_record)));
rec_priv->db_ctx = ctx;
result->store = db_rbt_store;
result->delete_rec = db_rbt_delete;
result->private_data = rec_priv;
if (found) {
rec_priv->node = r;
result->key = search_key;
result->value = search_val;
}
else {
rec_priv->node = NULL;
result->key.dptr = (uint8 *)
((char *)rec_priv + sizeof(*rec_priv));
result->key.dsize = key.dsize;
memcpy(result->key.dptr, key.dptr, key.dsize);
result->value = tdb_null;
}
return result;
}
static int db_rbt_fetch(struct db_context *db, TALLOC_CTX *mem_ctx,
TDB_DATA key, TDB_DATA *data)
{
struct db_rbt_ctx *ctx = talloc_get_type_abort(
db->private_data, struct db_rbt_ctx);
struct rb_node *n;
bool found = false;
struct db_rbt_node *r = NULL;
TDB_DATA search_key, search_val;
uint8_t *result;
n = ctx->tree.rb_node;
while (n != NULL) {
int res;
r = db_rbt2node(n);
db_rbt_parse_node(r, &search_key, &search_val);
res = db_rbt_compare(key, search_key);
if (res == -1) {
n = n->rb_left;
}
else if (res == 1) {
n = n->rb_right;
}
else {
found = true;
break;
}
}
if (!found) {
*data = tdb_null;
return 0;
}
result = (uint8 *)talloc_memdup(mem_ctx, search_val.dptr,
search_val.dsize);
if (result == NULL) {
return -1;
}
data->dptr = result;
data->dsize = search_val.dsize;
return 0;
}
static int db_rbt_traverse(struct db_context *db,
int (*f)(struct db_record *db,
void *private_data),
void *private_data)
{
/*
* Nobody uses this so far, and unused code is broken code :-)
*/
return -1;
}
static int db_rbt_get_seqnum(struct db_context *db)
{
return 0;
}
static int db_rbt_trans_dummy(struct db_context *db)
{
/*
* Transactions are pretty pointless in-memory, just return success.
*/
return 0;
}
struct db_context *db_open_rbt(TALLOC_CTX *mem_ctx)
{
struct db_context *result;
result = talloc(mem_ctx, struct db_context);
if (result == NULL) {
return NULL;
}
result->private_data = TALLOC_ZERO_P(result, struct db_rbt_ctx);
if (result->private_data == NULL) {
TALLOC_FREE(result);
return NULL;
}
result->fetch_locked = db_rbt_fetch_locked;
result->fetch = db_rbt_fetch;
result->traverse = db_rbt_traverse;
result->traverse_read = db_rbt_traverse;
result->get_seqnum = db_rbt_get_seqnum;
result->transaction_start = db_rbt_trans_dummy;
result->transaction_commit = db_rbt_trans_dummy;
result->transaction_cancel = db_rbt_trans_dummy;
return result;
}
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