libsemanage/src/database_join.c

/* Copyright (C) 2005 Red Hat, Inc. */

/* Object: dbase_join_t (Join)
 * Extends: dbase_llist_t (Linked List) 
 * Implements: dbase_t (Database)
 */

struct dbase_join;
typedef struct dbase_join dbase_t;
#define DBASE_DEFINED

#include <stdlib.h>

#include "user_internal.h"
#include "debug.h"
#include "handle.h"
#include "database_join.h"
#include "database_llist.h"

/* JOIN dbase */
struct dbase_join {

	/* Parent object - must always be 
	 * the first field - here we are using
	 * a linked list to store the records */
	dbase_llist_t llist;

	/* Backing databases - for each
	 * thing being joined  */
	dbase_config_t *join1;
	dbase_config_t *join2;

	/* JOIN extension */
	record_join_table_t *rjtable;
};

static int dbase_join_cache(semanage_handle_t * handle, dbase_join_t * dbase)
{

	/* Extract all the object tables information */
	dbase_t *dbase1 = dbase->join1->dbase;
	dbase_t *dbase2 = dbase->join2->dbase;
	dbase_table_t *dtable1 = dbase->join1->dtable;
	dbase_table_t *dtable2 = dbase->join2->dtable;
	record_table_t *rtable = dbase_llist_get_rtable(&dbase->llist);
	record_join_table_t *rjtable = dbase->rjtable;
	record_table_t *rtable1 = dtable1->get_rtable(dbase1);
	record_table_t *rtable2 = dtable2->get_rtable(dbase2);

	record_key_t *rkey = NULL;
	record_t *record = NULL;
	record1_t **records1 = NULL;
	record2_t **records2 = NULL;
	unsigned int rcount1 = 0, rcount2 = 0, i = 0, j = 0;

	/* Already cached */
	if (!dbase_llist_needs_resync(handle, &dbase->llist))
		return STATUS_SUCCESS;

	/* Update cache serial */
	dbase_llist_cache_init(&dbase->llist);
	if (dbase_llist_set_serial(handle, &dbase->llist) < 0)
		goto err;

	/* First cache any child dbase, which must
	 * be the first thing done when calling dbase
	 * functions internally */
	if (dtable1->cache(handle, dbase1) < 0)
		goto err;
	if (dtable2->cache(handle, dbase2) < 0)
		goto err;

	/* Fetch records */
	if (dtable1->list(handle, dbase1, &records1, &rcount1) < 0)
		goto err;
	if (dtable2->list(handle, dbase2, &records2, &rcount2) < 0)
		goto err;

	/* Sort for quicker merge later */
	qsort(records1, rcount1, sizeof(record1_t *),
	      (int (*)(const void *, const void *))rtable1->compare2_qsort);
	qsort(records2, rcount2, sizeof(record2_t *),
	      (int (*)(const void *, const void *))rtable2->compare2_qsort);

	/* Now merge into this dbase */
	while (i < rcount1 || j < rcount2) {
		int rc;

		/* End of one list, or the other */
		if (i == rcount1)
			rc = -1;
		else if (j == rcount2)
			rc = 1;

		/* Still more records to go, compare them */
		else {
			if (rtable1->key_extract(handle, records1[i], &rkey) <
			    0)
				goto err;

			rc = rtable2->compare(records2[j], rkey);

			rtable->key_free(rkey);
			rkey = NULL;
		}

		/* Missing record1 data */
		if (rc < 0) {
			if (rjtable->join(handle, NULL,
					  records2[j], &record) < 0)
				goto err;
			j++;
		}

		/* Missing record2 data */
		else if (rc > 0) {
			if (rjtable->join(handle, records1[i],
					  NULL, &record) < 0)
				goto err;
			i++;
		}

		/* Both records available */
		else {
			if (rjtable->join(handle, records1[i],
					  records2[j], &record) < 0)
				goto err;

			i++;
			j++;
		}

		/* Add result record to database */
		if (dbase_llist_cache_prepend(handle, &dbase->llist, record) <
		    0)
			goto err;

		rtable->free(record);
		record = NULL;
	}

	/* Update cache serial */
	if (dbase_llist_set_serial(handle, &dbase->llist) < 0)
		goto err;

	for (i = 0; i < rcount1; i++)
		rtable1->free(records1[i]);
	for (i = 0; i < rcount2; i++)
		rtable2->free(records2[i]);
	free(records1);
	free(records2);
	return STATUS_SUCCESS;

      err:
	ERR(handle, "could not cache join database");
	for (i = 0; i < rcount1; i++)
		rtable1->free(records1[i]);
	for (i = 0; i < rcount2; i++)
		rtable2->free(records2[i]);
	free(records1);
	free(records2);
	rtable->key_free(rkey);
	rtable->free(record);
	dbase_llist_drop_cache(&dbase->llist);
	return STATUS_ERR;
}

/* Flush database */
static int dbase_join_flush(semanage_handle_t * handle, dbase_join_t * dbase)
{

	/* Extract all the object tables information */
	dbase_t *dbase1 = dbase->join1->dbase;
	dbase_t *dbase2 = dbase->join2->dbase;
	dbase_table_t *dtable1 = dbase->join1->dtable;
	dbase_table_t *dtable2 = dbase->join2->dtable;
	record_table_t *rtable = dbase_llist_get_rtable(&dbase->llist);
	record_join_table_t *rjtable = dbase->rjtable;
	record_table_t *rtable1 = dtable1->get_rtable(dbase1);
	record_table_t *rtable2 = dtable2->get_rtable(dbase2);

	cache_entry_t *ptr;
	record_key_t *rkey = NULL;
	record1_t *record1 = NULL;
	record2_t *record2 = NULL;

	/* No effect of flush */
	if (!dbase_llist_is_modified(&dbase->llist))
		return STATUS_SUCCESS;

	/* Then clear all records from the cache.
	 * This is *not* the same as dropping the cache - it's an explicit
	 * request to delete all current records. We need to do 
	 * this because we don't store delete deltas for the join,
	 * so we must re-add all records from scratch */
	if (dtable1->clear(handle, dbase1) < 0)
		goto err;
	if (dtable2->clear(handle, dbase2) < 0)
		goto err;

	/* For each record, split, and add parts into their corresponding databases */
	for (ptr = dbase->llist.cache_tail; ptr != NULL; ptr = ptr->prev) {

		if (rtable->key_extract(handle, ptr->data, &rkey) < 0)
			goto err;

		if (rjtable->split(handle, ptr->data, &record1, &record2) < 0)
			goto err;

		if (dtable1->add(handle, dbase1, rkey, record1) < 0)
			goto err;

		if (dtable2->add(handle, dbase2, rkey, record2) < 0)
			goto err;

		rtable->key_free(rkey);
		rtable1->free(record1);
		rtable2->free(record2);
		rkey = NULL;
		record1 = NULL;
		record2 = NULL;
	}

	/* Note that this function does not flush the child databases, it
	 * leaves that decision up to higher-level code */

	dbase_llist_set_modified(&dbase->llist, 0);
	return STATUS_SUCCESS;

      err:
	ERR(handle, "could not flush join database");
	rtable->key_free(rkey);
	rtable1->free(record1);
	rtable2->free(record2);
	return STATUS_ERR;
}

int dbase_join_init(semanage_handle_t * handle,
		    record_table_t * rtable,
		    record_join_table_t * rjtable,
		    dbase_config_t * join1,
		    dbase_config_t * join2, dbase_t ** dbase)
{

	dbase_join_t *tmp_dbase = malloc(sizeof(dbase_join_t));

	if (!tmp_dbase)
		goto omem;

	dbase_llist_init(&tmp_dbase->llist, rtable, &SEMANAGE_JOIN_DTABLE);

	tmp_dbase->rjtable = rjtable;
	tmp_dbase->join1 = join1;
	tmp_dbase->join2 = join2;

	*dbase = tmp_dbase;

	return STATUS_SUCCESS;

      omem:
	ERR(handle, "out of memory, could not initialize join database");
	free(tmp_dbase);
	return STATUS_ERR;
}

/* Release dbase resources */
void dbase_join_release(dbase_join_t * dbase)
{

	dbase_llist_drop_cache(&dbase->llist);
	free(dbase);
}

/* JOIN dbase - method table implementation */
dbase_table_t SEMANAGE_JOIN_DTABLE = {

	/* Cache/Transactions */
	.cache = dbase_join_cache,
	.drop_cache = (void *)dbase_llist_drop_cache,
	.flush = dbase_join_flush,
	.is_modified = (void *)dbase_llist_is_modified,

	/* Database API */
	.iterate = (void *)dbase_llist_iterate,
	.exists = (void *)dbase_llist_exists,
	.list = (void *)dbase_llist_list,
	.add = (void *)dbase_llist_add,
	.set = (void *)dbase_llist_set,
	.del = (void *)dbase_llist_del,
	.clear = (void *)dbase_llist_clear,
	.modify = (void *)dbase_llist_modify,
	.query = (void *)dbase_llist_query,
	.count = (void *)dbase_llist_count,

	/* Polymorphism */
	.get_rtable = (void *)dbase_llist_get_rtable
};