kernel/os/refstr.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #include <sys/systm.h>
  28 #include <sys/param.h>
  29 #include <sys/atomic.h>
  30 #include <sys/kmem.h>
  31 #include <sys/refstr.h>
  32 #include <sys/refstr_impl.h>
  33
  34 refstr_t *
  35 refstr_alloc(const char *str)
  36 {
  37         refstr_t *rsp;
  38         size_t size = sizeof (rsp->rs_size) + sizeof (rsp->rs_refcnt) +
  39                 strlen(str) + 1;
  40
  41         ASSERT(size <= UINT32_MAX);
  42         rsp = kmem_alloc(size, KM_SLEEP);
  43         rsp->rs_size = (uint32_t)size;
  44         rsp->rs_refcnt = 1;
  45         (void) strcpy(rsp->rs_string, str);
  46         return (rsp);
  47 }
  48
  49 const char *
  50 refstr_value(refstr_t *rsp)
  51 {
  52         return (rsp != NULL ? (const char *)rsp->rs_string : NULL);
  53 }
  54
  55 void
  56 refstr_hold(refstr_t *rsp)
  57 {
  58         atomic_inc_32(&rsp->rs_refcnt);
  59 }
  60
  61 void
  62 refstr_rele(refstr_t *rsp)
  63 {
  64         if (atomic_dec_32_nv(&rsp->rs_refcnt) == 0)
  65                 kmem_free(rsp, (size_t)rsp->rs_size);
  66 }