81 lines
1.7 KiB
C
81 lines
1.7 KiB
C
|
// SPDX-License-Identifier: GPL-2.0
|
||
|
|
/*
|
||
|
|
* Copyright (c) 2015-2019 TrustKernel Incorporated
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/slab.h>
|
||
|
|
#include <linux/string.h>
|
||
|
|
#include "handle.h"
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Define the initial capacity of the database. It should be a low number
|
||
|
|
* multiple of 2 since some databases a likely to only use a few handles.
|
||
|
|
* Since the algorithm is to doubles up when growing it shouldn't cause a
|
||
|
|
* noticeable overhead on large databases.
|
||
|
|
*/
|
||
|
|
#define HANDLE_DB_INITIAL_MAX_PTRS 4
|
||
|
|
|
||
|
|
void handle_db_destroy(struct handle_db *db)
|
||
|
|
{
|
||
|
|
if (db) {
|
||
|
|
kfree(db->ptrs);
|
||
|
|
db->ptrs = NULL;
|
||
|
|
db->max_ptrs = 0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
int handle_get(struct handle_db *db, void *ptr)
|
||
|
|
{
|
||
|
|
unsigned int n;
|
||
|
|
void *p;
|
||
|
|
unsigned int new_max_ptrs;
|
||
|
|
|
||
|
|
if (!db || !ptr)
|
||
|
|
return -1;
|
||
|
|
|
||
|
|
/* Try to find an empty location */
|
||
|
|
for (n = 0; n < db->max_ptrs; n++) {
|
||
|
|
if (!db->ptrs[n]) {
|
||
|
|
db->ptrs[n] = ptr;
|
||
|
|
return n;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* No location available, grow the ptrs array */
|
||
|
|
if (db->max_ptrs)
|
||
|
|
new_max_ptrs = db->max_ptrs * 2;
|
||
|
|
else
|
||
|
|
new_max_ptrs = HANDLE_DB_INITIAL_MAX_PTRS;
|
||
|
|
p = krealloc(db->ptrs, new_max_ptrs * sizeof(void *), GFP_KERNEL);
|
||
|
|
if (!p)
|
||
|
|
return -1;
|
||
|
|
db->ptrs = p;
|
||
|
|
memset(db->ptrs + db->max_ptrs, 0,
|
||
|
|
(new_max_ptrs - db->max_ptrs) * sizeof(void *));
|
||
|
|
db->max_ptrs = new_max_ptrs;
|
||
|
|
|
||
|
|
/* Since n stopped at db->max_ptrs there is an empty location there */
|
||
|
|
db->ptrs[n] = ptr;
|
||
|
|
return n;
|
||
|
|
}
|
||
|
|
|
||
|
|
void *handle_put(struct handle_db *db, int handle)
|
||
|
|
{
|
||
|
|
void *p;
|
||
|
|
|
||
|
|
if (!db || handle < 0 || (unsigned int) handle >= db->max_ptrs)
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
p = db->ptrs[handle];
|
||
|
|
db->ptrs[handle] = NULL;
|
||
|
|
return p;
|
||
|
|
}
|
||
|
|
|
||
|
|
void *handle_lookup(struct handle_db *db, int handle)
|
||
|
|
{
|
||
|
|
if (!db || handle < 0 || (unsigned int) handle >= db->max_ptrs)
|
||
|
|
return NULL;
|
||
|
|
|
||
|
|
return db->ptrs[handle];
|
||
|
|
}
|