os_handle.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1998-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: os_handle.c,v 12.2 2005/08/10 15:47:25 bostic Exp $
 */

#include "db_config.h"

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

#include <fcntl.h>
#include <string.h>
#endif

#include "db_int.h"

/*
 * __os_openhandle --
 *      Open a file, using POSIX 1003.1 open flags.
 *
 * PUBLIC: int __os_openhandle
 * PUBLIC:     __P((DB_ENV *, const char *, int, int, DB_FH **));
 */
int
__os_openhandle(dbenv, name, flags, mode, fhpp)
        DB_ENV *dbenv;
        const char *name;
        int flags, mode;
        DB_FH **fhpp;
{
        DB_FH *fhp;
        u_int nrepeat, retries;
        int ret;
#ifdef HAVE_VXWORKS
        int newflags;
#endif

        if ((ret = __os_calloc(dbenv, 1, sizeof(DB_FH), fhpp)) != 0)
                return (ret);
        fhp = *fhpp;

        /* If the application specified an interface, use it. */
        if (DB_GLOBAL(j_open) != NULL) {
                if ((fhp->fd = DB_GLOBAL(j_open)(name, flags, mode)) == -1) {
                        ret = __os_get_errno();
                        goto err;
                }
                F_SET(fhp, DB_FH_OPENED);
                return (0);
        }

        retries = 0;
        for (nrepeat = 1; nrepeat < 4; ++nrepeat) {
                ret = 0;
#ifdef  HAVE_VXWORKS
                /*
                 * VxWorks does not support O_CREAT on open, you have to use
                 * creat() instead.  (It does not support O_EXCL or O_TRUNC
                 * either, even though they are defined "for future support".)
                 * We really want the POSIX behavior that if O_CREAT is set,
                 * we open if it exists, or create it if it doesn't exist.
                 * If O_CREAT is specified, single thread and try to open the
                 * file.  If successful, and O_EXCL return EEXIST.  If
                 * unsuccessful call creat and then end single threading.
                 */
                if (LF_ISSET(O_CREAT)) {
                        DB_BEGIN_SINGLE_THREAD;
                        newflags = flags & ~(O_CREAT | O_EXCL);
                        if ((fhp->fd = open(name, newflags, mode)) != -1) {
                                /*
                                 * We need to mark the file opened at this
                                 * point so that if we get any error below
                                 * we will properly close the fd we just
                                 * opened on the error path.
                                 */
                                F_SET(fhp, DB_FH_OPENED);
                                if (LF_ISSET(O_EXCL)) {
                                        /*
                                         * If we get here, want O_EXCL create,
                                         * and the file exists.  Close and
                                         * return EEXISTS.
                                         */
                                        DB_END_SINGLE_THREAD;
                                        ret = EEXIST;
                                        goto err;
                                }
                                /*
                                 * XXX
                                 * Assume any error means non-existence.
                                 * Unfortunately return values (even for
                                 * non-existence) are driver specific so
                                 * there is no single error we can use to
                                 * verify we truly got the equivalent of
                                 * ENOENT.
                                 */
                        } else
                                fhp->fd = creat(name, newflags);
                        DB_END_SINGLE_THREAD;
                } else
                /* FALLTHROUGH */
#endif
#ifdef __VMS
                /*
                 * !!!
                 * Open with full sharing on VMS.
                 *
                 * We use these flags because they are the ones set by the VMS
                 * CRTL mmap() call when it opens a file, and we have to be
                 * able to open files that mmap() has previously opened, e.g.,
                 * when we're joining already existing DB regions.
                 */
                fhp->fd = open(name, flags, mode, "shr=get,put,upd,del,upi");
#else
                fhp->fd = open(name, flags, mode);
#endif
                if (fhp->fd != -1) {
                        F_SET(fhp, DB_FH_OPENED);

#if defined(HAVE_FCNTL_F_SETFD)
                        /* Deny file descriptor access to any child process. */
                        if (fcntl(fhp->fd, F_SETFD, 1) == -1) {
                                ret = __os_get_errno();
                                __db_err(dbenv,
                                    "fcntl(F_SETFD): %s", strerror(ret));
                                goto err;
                        }
#endif
                        break;
                }

                switch (ret = __os_get_errno()) {
                case EMFILE:
                case ENFILE:
                case ENOSPC:
                        /*
                         * If it's a "temporary" error, we retry up to 3 times,
                         * waiting up to 12 seconds.  While it's not a problem
                         * if we can't open a database, an inability to open a
                         * log file is cause for serious dismay.
                         */
                        __os_sleep(dbenv, nrepeat * 2, 0);
                        break;
                case EAGAIN:
                case EBUSY:
                case EINTR:
                        /*
                         * If an EAGAIN, EBUSY or EINTR, retry immediately for
                         * DB_RETRY times.
                         */
                        if (++retries < DB_RETRY)
                                --nrepeat;
                        break;
                default:
                        break;
                }
        }

err:    if (ret != 0) {
                (void)__os_closehandle(dbenv, fhp);
                *fhpp = NULL;
        }

        return (ret);
}

/*
 * __os_closehandle --
 *      Close a file.
 *
 * PUBLIC: int __os_closehandle __P((DB_ENV *, DB_FH *));
 */
int
__os_closehandle(dbenv, fhp)
        DB_ENV *dbenv;
        DB_FH *fhp;
{
        int ret;

        ret = 0;

        /*
         * If we have a valid handle, close it and unlink any temporary
         * file.
         */
        if (F_ISSET(fhp, DB_FH_OPENED)) {
                if (DB_GLOBAL(j_close) != NULL)
                        ret = DB_GLOBAL(j_close)(fhp->fd);
                else
                        RETRY_CHK((close(fhp->fd)), ret);

                if (ret != 0)
                        __db_err(dbenv, "close: %s", strerror(ret));

                /* Unlink the file if we haven't already done so. */
                if (F_ISSET(fhp, DB_FH_UNLINK)) {
                        (void)__os_unlink(dbenv, fhp->name);
                        __os_free(dbenv, fhp->name);
                }
        }

        __os_free(dbenv, fhp);

        return (ret);
}

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