ex_apprec.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: ex_apprec.c,v 12.1 2005/06/16 20:22:06 bostic Exp $
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <db.h>

#include "ex_apprec.h"

int     apprec_dispatch __P((DB_ENV *, DBT *, DB_LSN *, db_recops));
int     open_env __P((const char *, FILE *, const char *, DB_ENV **));
int     verify_absence __P((DB_ENV *, const char *));
int     verify_presence __P((DB_ENV *, const char *));

int
main(argc, argv)
        int argc;
        char *argv[];
{
        extern char *optarg;
        DB_ENV *dbenv;
        DB_LSN lsn;
        DB_TXN *txn;
        DBT dirnamedbt;
        int ret;
        const char *home;
        char ch, dirname[256];
        const char *progname = "ex_apprec";             /* Program name. */

        /* Default home. */
        home = "TESTDIR";

        while ((ch = getopt(argc, argv, "h:")) != EOF)
                switch (ch) {
                case 'h':
                        home = optarg;
                        break;
                default:
                        fprintf(stderr, "usage: %s [-h home]", progname);
                        exit(EXIT_FAILURE);
                }

        printf("Set up environment.\n");
        if ((ret = open_env(home, stderr, progname, &dbenv)) != 0)
                return (EXIT_FAILURE);

        printf("Create a directory in a transaction.\n");
        /*
         * This application's convention is to log the full directory name,
         * including trailing nul.
         */
        memset(&dirnamedbt, 0, sizeof(dirnamedbt));
        sprintf(dirname, "%s/MYDIRECTORY", home);
        dirnamedbt.data = dirname;
        dirnamedbt.size = strlen(dirname) + 1;

        if ((ret = dbenv->txn_begin(dbenv, NULL, &txn, 0)) != 0) {
                dbenv->err(dbenv, ret, "txn_begin");
                return (EXIT_FAILURE);
        }

        /* Remember, always log actions before you execute them! */
        memset(&lsn, 0, sizeof(lsn));
        if ((ret =
            ex_apprec_mkdir_log(dbenv, txn, &lsn, 0, &dirnamedbt)) != 0) {
                dbenv->err(dbenv, ret, "mkdir_log");
                return (EXIT_FAILURE);
        }
        if (mkdir(dirname, 0755) != 0) {
                dbenv->err(dbenv, errno, "mkdir");
                return (EXIT_FAILURE);
        }

        printf("Verify the directory's presence: ");
        verify_presence(dbenv, dirname);
        printf("check.\n");

        /* Now abort the transaction and verify that the directory goes away. */
        printf("Abort the transaction.\n");
        if ((ret = txn->abort(txn)) != 0) {
                dbenv->err(dbenv, ret, "txn_abort");
                return (EXIT_FAILURE);
        }

        printf("Verify the directory's absence: ");
        verify_absence(dbenv, dirname);
        printf("check.\n");

        /* Now do the same thing over again, only with a commit this time. */
        printf("Create a directory in a transaction.\n");
        memset(&dirnamedbt, 0, sizeof(dirnamedbt));
        sprintf(dirname, "%s/MYDIRECTORY", home);
        dirnamedbt.data = dirname;
        dirnamedbt.size = strlen(dirname) + 1;
        if ((ret = dbenv->txn_begin(dbenv, NULL, &txn, 0)) != 0) {
                dbenv->err(dbenv, ret, "txn_begin");
                return (EXIT_FAILURE);
        }

        memset(&lsn, 0, sizeof(lsn));
        if ((ret =
            ex_apprec_mkdir_log(dbenv, txn, &lsn, 0, &dirnamedbt)) != 0) {
                dbenv->err(dbenv, ret, "mkdir_log");
                return (EXIT_FAILURE);
        }
        if (mkdir(dirname, 0755) != 0) {
                dbenv->err(dbenv, errno, "mkdir");
                return (EXIT_FAILURE);
        }

        printf("Verify the directory's presence: ");
        verify_presence(dbenv, dirname);
        printf("check.\n");

        /* Now abort the transaction and verify that the directory goes away. */
        printf("Commit the transaction.\n");
        if ((ret = txn->commit(txn, 0)) != 0) {
                dbenv->err(dbenv, ret, "txn_commit");
                return (EXIT_FAILURE);
        }

        printf("Verify the directory's presence: ");
        verify_presence(dbenv, dirname);
        printf("check.\n");

        printf("Now remove the directory, then run recovery.\n");
        if ((ret = dbenv->close(dbenv, 0)) != 0) {
                fprintf(stderr, "DB_ENV->close: %s\n", db_strerror(ret));
                return (EXIT_FAILURE);
        }
        if (rmdir(dirname) != 0) {
                fprintf(stderr,
                    "%s: rmdir failed with error %s", progname,
                    strerror(errno));
        }
        verify_absence(dbenv, dirname);

        /* Opening with DB_RECOVER runs recovery. */
        if ((ret = open_env(home, stderr, progname, &dbenv)) != 0)
                return (EXIT_FAILURE);

        printf("Verify the directory's presence: ");
        verify_presence(dbenv, dirname);
        printf("check.\n");

        /* Close the handle. */
        if ((ret = dbenv->close(dbenv, 0)) != 0) {
                fprintf(stderr, "DB_ENV->close: %s\n", db_strerror(ret));
                return (EXIT_FAILURE);
        }

        return (EXIT_SUCCESS);
}

int
open_env(home, errfp, progname, dbenvp)
        const char *home, *progname;
        FILE *errfp;
        DB_ENV **dbenvp;
{
        DB_ENV *dbenv;
        int ret;

        /*
         * Create an environment object and initialize it for error
         * reporting.
         */
        if ((ret = db_env_create(&dbenv, 0)) != 0) {
                fprintf(errfp, "%s: %s\n", progname, db_strerror(ret));
                return (ret);
        }
        dbenv->set_errfile(dbenv, errfp);
        dbenv->set_errpfx(dbenv, progname);

        /* Set up our custom recovery dispatch function. */
        if ((ret = dbenv->set_app_dispatch(dbenv, apprec_dispatch)) != 0) {
                dbenv->err(dbenv, ret, "set_app_dispatch");
                return (ret);
        }

        /*
         * Open the environment with full transactional support, running
         * recovery.
         */
        if ((ret =
            dbenv->open(dbenv, home, DB_CREATE | DB_RECOVER | DB_INIT_LOCK |
            DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN, 0)) != 0) {
                dbenv->err(dbenv, ret, "environment open: %s", home);
                dbenv->close(dbenv, 0);
                return (ret);
        }

        *dbenvp = dbenv;
        return (0);
}

/*
 * Sample application dispatch function to handle user-specified log record
 * types.
 */
int
apprec_dispatch(dbenv, dbt, lsn, op)
        DB_ENV *dbenv;
        DBT *dbt;
        DB_LSN *lsn;
        db_recops op;
{
        u_int32_t rectype;

        /* Pull the record type out of the log record. */
        memcpy(&rectype, dbt->data, sizeof(rectype));

        switch (rectype) {
        case DB_ex_apprec_mkdir:
                return (ex_apprec_mkdir_recover(dbenv, dbt, lsn, op, NULL));
        default:
                /*
                 * We've hit an unexpected, allegedly user-defined record
                 * type.
                 */
                dbenv->errx(dbenv, "Unexpected log record type encountered");
                return (EINVAL);
        }
}

int
verify_absence(dbenv, dirname)
        DB_ENV *dbenv;
        const char *dirname;
{

        if (access(dirname, F_OK) == 0) {
                dbenv->errx(dbenv, "Error--directory present!");
                exit(EXIT_FAILURE);
        }

        return (0);
}

int
verify_presence(dbenv, dirname)
        DB_ENV *dbenv;
        const char *dirname;
{

        if (access(dirname, F_OK) != 0) {
                dbenv->errx(dbenv, "Error--directory not present!");
                exit(EXIT_FAILURE);
        }

        return (0);
}

---