libfmevent/common/fmev_util.c

	fmev_util.c revision 49b225e1cfa7bbf7738d4df0a03f18e3283426eb
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Subscription event access interfaces.
 */

#include <sys/types.h>
#include <pthread.h>
#include <umem.h>
#include <fm/libfmevent.h>

#include "fmev_impl.h"

static pthread_key_t fmev_tsdkey = PTHREAD_ONCE_KEY_NP;
static int key_inited;

/*
 * Thread and handle specific data.
 */
struct fmev_tsd {
    fmev_err_t ts_lasterr;
};

static void
fmev_tsd_destructor(void *data)
{
    umem_free(data, sizeof (struct fmev_tsd));
}

/*
 * Called only from fmev_shdl_init.  Check we are opening a valid version
 * of the ABI.
 */
int
fmev_api_init(struct fmev_hdl_cmn *hc)
{
    if (!fmev_api_enter(NULL, 0))
        return (0);
    /*
     * We implement only version 1 of the ABI at this point.
     */
    if (hc->hc_api_vers != LIBFMEVENT_VERSION_1) {
        if (key_inited)
            (void) fmev_seterr(FMEVERR_VERSION_MISMATCH);
        return (0);
    }

    return (1);
}

/*
 * On entry to other libfmevent API members we call fmev_api_enter.
 * Some thread-specific data is used to keep a per-thread error value.
 * The version opened must be no greater than the latest version but can
 * be older.  The ver_intro is the api version at which the interface
 * was added - the caller must have opened at least this version.
 */
int
fmev_api_enter(struct fmev_hdl_cmn *hc, uint32_t ver_intro)
{
    struct fmev_tsd *tsd;

    /* Initialize key on first visit */
    if (!key_inited) {
        (void) pthread_key_create_once_np(&fmev_tsdkey,
            fmev_tsd_destructor);
        key_inited = 1;
    }

    /*
     * Allocate TSD for error value for this thread.  It is only
     * freed if/when the thread exits.
     */
    if ((tsd = pthread_getspecific(fmev_tsdkey)) == NULL) {
        if ((tsd = umem_alloc(sizeof (*tsd), UMEM_DEFAULT)) == NULL ||
            pthread_setspecific(fmev_tsdkey, (const void *)tsd) != 0) {
            if (tsd)
                umem_free(tsd, sizeof (*tsd));
            return (0); /* no error set, but what can we do */
        }
    }

    tsd->ts_lasterr = 0;

    if (hc == NULL) {
        return (1);
    }

    /* Enforce version adherence. */
    if (ver_intro > hc->hc_api_vers ||
        hc->hc_api_vers > LIBFMEVENT_VERSION_LATEST ||
        ver_intro > LIBFMEVENT_VERSION_LATEST) {
        tsd->ts_lasterr = FMEVERR_VERSION_MISMATCH;
        return (0);
    }

    return (1);
}

/*
 * Called on any fmev_shdl_fini.  Free the TSD for this thread.  If this
 * thread makes other API calls for other open handles, or opens a new
 * handle, then TSD will be allocated again in fmev_api_enter.
 */
void
fmev_api_freetsd(void)
{
    struct fmev_tsd *tsd;

    if ((tsd = pthread_getspecific(fmev_tsdkey)) != NULL) {
        (void) pthread_setspecific(fmev_tsdkey, NULL);
        fmev_tsd_destructor((void *)tsd);
    }
}

/*
 * To return an error condition an API member first sets the error type
 * with a call to fmev_seterr and then returns NULL or whatever it wants.
 * The caller can then retrieve the per-thread error type using fmev_errno
 * or format it with fmev_strerr.
 */
fmev_err_t
fmev_seterr(fmev_err_t error)
{
    struct fmev_tsd *tsd;

    ASSERT(key_inited);

    if ((tsd = pthread_getspecific(fmev_tsdkey)) != NULL)
        tsd->ts_lasterr = error;

    return (error);
}

/*
 * fmev_errno is a macro defined in terms of the following function.  It
 * can be used to dereference the last error value on the current thread;
 * it must not be used to assign to fmev_errno.
 */

const fmev_err_t apierr = FMEVERR_API;
const fmev_err_t unknownerr = FMEVERR_UNKNOWN;

const fmev_err_t *
__fmev_errno(void)
{
    struct fmev_tsd *tsd;

    if (!key_inited)
        return (&apierr);

    if ((tsd = pthread_getspecific(fmev_tsdkey)) == NULL)
        return (&unknownerr);

    return ((const fmev_err_t *)&tsd->ts_lasterr);
}