os_region.c

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/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998, 1999, 2000
 *      Sleepycat Software.  All rights reserved.
 */

#include "config.h"

#ifndef lint
static const char revid[] = "$Id: os__region_8c-source.html,v 1.1 2008/06/08 10:21:27 sebdiaz Exp $";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <errno.h>
#endif

#include "db_int.h"
#include "os_jump.h"

/*
 * CDB___os_r_attach --
 *      Attach to a shared memory region.
 *
 * PUBLIC: int CDB___os_r_attach __P((DB_ENV *, REGINFO *, REGION *));
 */
int
CDB___os_r_attach(dbenv, infop, rp)
        DB_ENV *dbenv;
        REGINFO *infop;
        REGION *rp;
{
        /* Round off the requested size for the underlying VM. */
        OS_VMROUNDOFF(rp->size);

#ifdef DB_REGIONSIZE_MAX
        /* Some architectures have hard limits on the maximum region size. */
        if (rp->size > DB_REGIONSIZE_MAX) {
                CDB___db_err(dbenv, "region size %lu is too large; maximum is %lu",
                    (u_long)rp->size, (u_long)DB_REGIONSIZE_MAX);
                return (EINVAL);
        }
#endif

        /*
         * If a region is private, malloc the memory.
         *
         * !!!
         * If this fails because the region is too large to malloc, mmap(2)
         * using the MAP_ANON or MAP_ANONYMOUS flags would be an alternative.
         * I don't know of any architectures (yet!) where malloc is a problem.
         */
        if (F_ISSET(dbenv, DB_ENV_PRIVATE)) {
#if defined(MUTEX_NO_MALLOC_LOCKS)
                /*
                 * !!!
                 * There exist spinlocks that don't work in malloc memory, e.g.,
                 * the HP/UX msemaphore interface.  If we don't have locks that
                 * will work in malloc memory, we better not be private or not
                 * be threaded.
                 */
                if (F_ISSET(dbenv, DB_ENV_THREAD)) {
                        CDB___db_err(dbenv, "%s",
    "architecture does not support locks inside process-local (malloc) memory");
                        CDB___db_err(dbenv, "%s",
    "application may not specify both DB_PRIVATE and DB_THREAD");
                        return (EINVAL);
                }
#endif
                return (CDB___os_malloc(dbenv, rp->size, NULL, &infop->addr));
        }

        /* If the user replaced the map call, call through their interface. */
        if (CDB___db_jump.j_map != NULL)
                return (CDB___db_jump.j_map(infop->name,
                    rp->size, 1, 0, &infop->addr));

        return (CDB___os_r_sysattach(dbenv, infop, rp));
}

/*
 * CDB___os_r_detach --
 *      Detach from a shared memory region.
 *
 * PUBLIC: int CDB___os_r_detach __P((DB_ENV *, REGINFO *, int));
 */
int
CDB___os_r_detach(dbenv, infop, destroy)
        DB_ENV *dbenv;
        REGINFO *infop;
        int destroy;
{
        REGION *rp;

        rp = infop->rp;

        /* If a region is private, free the memory. */
        if (F_ISSET(dbenv, DB_ENV_PRIVATE)) {
                CDB___os_free(infop->addr, rp->size);
                return (0);
        }

        /* If the user replaced the map call, call through their interface. */
        if (CDB___db_jump.j_unmap != NULL)
                return (CDB___db_jump.j_unmap(infop->addr, rp->size));

        return (CDB___os_r_sysdetach(dbenv, infop, destroy));
}

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