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env_open.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2006
 *    Oracle Corporation.  All rights reserved.
 *
 * $Id: env_open.c,v 12.71 2006/08/24 14:45:39 bostic Exp $
 */

#include "db_config.h"

#include "db_int.h"
#include "dbinc/crypto.h"
#include "dbinc/db_page.h"
#include "dbinc/btree.h"
#include "dbinc/lock.h"
#include "dbinc/log.h"
#include "dbinc/mp.h"
#include "dbinc/txn.h"

static int __db_tmp_open __P((DB_ENV *, u_int32_t, char *, DB_FH **));
static int __env_refresh __P((DB_ENV *, u_int32_t, int));

/*
 * db_version --
 *    Return version information.
 *
 * EXTERN: char *db_version __P((int *, int *, int *));
 */
char *
db_version(majverp, minverp, patchp)
      int *majverp, *minverp, *patchp;
{
      if (majverp != NULL)
            *majverp = DB_VERSION_MAJOR;
      if (minverp != NULL)
            *minverp = DB_VERSION_MINOR;
      if (patchp != NULL)
            *patchp = DB_VERSION_PATCH;
      return ((char *)DB_VERSION_STRING);
}

/*
 * __env_open_pp --
 *    DB_ENV->open pre/post processing.
 *
 * PUBLIC: int __env_open_pp __P((DB_ENV *, const char *, u_int32_t, int));
 */
int
__env_open_pp(dbenv, db_home, flags, mode)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
      int mode;
{
      int ret;

#undef      OKFLAGS
#define     OKFLAGS                                               \
      (DB_CREATE | DB_INIT_CDB | DB_INIT_LOCK | DB_INIT_LOG |           \
      DB_INIT_MPOOL | DB_INIT_REP | DB_INIT_TXN | DB_LOCKDOWN |   \
      DB_PRIVATE | DB_RECOVER | DB_RECOVER_FATAL | DB_REGISTER |  \
      DB_SYSTEM_MEM | DB_THREAD | DB_USE_ENVIRON | DB_USE_ENVIRON_ROOT)
#undef      OKFLAGS_CDB
#define     OKFLAGS_CDB                                     \
      (DB_CREATE | DB_INIT_CDB | DB_INIT_MPOOL | DB_LOCKDOWN |    \
      DB_PRIVATE | DB_SYSTEM_MEM | DB_THREAD |              \
      DB_USE_ENVIRON | DB_USE_ENVIRON_ROOT)

      if ((ret = __db_fchk(dbenv, "DB_ENV->open", flags, OKFLAGS)) != 0)
            return (ret);
      if ((ret = __db_fcchk(
          dbenv, "DB_ENV->open", flags, DB_INIT_CDB, ~OKFLAGS_CDB)) != 0)
            return (ret);
      if (LF_ISSET(DB_REGISTER)) {
            if (!__os_support_db_register()) {
                  __db_errx(dbenv,
           "Berkeley DB library does not support DB_REGISTER on this system");
                  return (EINVAL);
            }
            if ((ret = __db_fcchk(dbenv, "DB_ENV->open", flags,
                DB_PRIVATE, DB_REGISTER | DB_SYSTEM_MEM)) != 0)
                  return (ret);
            if (!LF_ISSET(DB_INIT_TXN)) {
                  __db_errx(
                      dbenv, "registration requires transaction support");
                  return (EINVAL);
            }
      }
      if (LF_ISSET(DB_INIT_REP)) {
            if (!__os_support_replication()) {
                  __db_errx(dbenv,
           "Berkeley DB library does not support replication on this system");
                  return (EINVAL);
            }
            if (!LF_ISSET(DB_INIT_LOCK)) {
                  __db_errx(dbenv,
                      "replication requires locking support");
                  return (EINVAL);
            }
            if (!LF_ISSET(DB_INIT_TXN)) {
                  __db_errx(
                      dbenv, "replication requires transaction support");
                  return (EINVAL);
            }
      }
      if (LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL)) {
            if ((ret = __db_fcchk(dbenv,
                "DB_ENV->open", flags, DB_RECOVER, DB_RECOVER_FATAL)) != 0)
                  return (ret);
            if ((ret = __db_fcchk(dbenv,
                "DB_ENV->open", flags, DB_REGISTER, DB_RECOVER_FATAL)) != 0)
                  return (ret);
            if (!LF_ISSET(DB_CREATE)) {
                  __db_errx(dbenv, "recovery requires the create flag");
                  return (EINVAL);
            }
            if (!LF_ISSET(DB_INIT_TXN)) {
                  __db_errx(
                      dbenv, "recovery requires transaction support");
                  return (EINVAL);
            }
      }

#ifdef HAVE_MUTEX_THREAD_ONLY
      /*
       * Currently we support one kind of mutex that is intra-process only,
       * POSIX 1003.1 pthreads, because a variety of systems don't support
       * the full pthreads API, and our only alternative is test-and-set.
       */
      if (!LF_ISSET(DB_PRIVATE)) {
            __db_errx(dbenv,
       "Berkeley DB library configured to support only private environments");
            return (EINVAL);
      }
#endif

#ifdef HAVE_MUTEX_FCNTL
      /*
       * !!!
       * We need a file descriptor for fcntl(2) locking.  We use the file
       * handle from the REGENV file for this purpose.
       *
       * Since we may be using shared memory regions, e.g., shmget(2), and
       * not a mapped-in regular file, the backing file may be only a few
       * bytes in length.  So, this depends on the ability to call fcntl to
       * lock file offsets much larger than the actual physical file.  I
       * think that's safe -- besides, very few systems actually need this
       * kind of support, SunOS is the only one still in wide use of which
       * I'm aware.
       *
       * The error case is if an application lacks spinlocks and wants to be
       * threaded.  That doesn't work because fcntl will lock the underlying
       * process, including all its threads.
       */
      if (F_ISSET(dbenv, DB_ENV_THREAD)) {
            __db_errx(dbenv,
          "architecture lacks fast mutexes: applications cannot be threaded");
            return (EINVAL);
      }
#endif

      return (__env_open(dbenv, db_home, flags, mode));
}

/*
 * __env_open --
 *    DB_ENV->open.
 *
 * PUBLIC: int __env_open __P((DB_ENV *, const char *, u_int32_t, int));
 */
int
__env_open(dbenv, db_home, flags, mode)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
      int mode;
{
      DB_THREAD_INFO *ip;
      REGINFO *infop;
      u_int32_t init_flags, orig_flags;
      int register_recovery, rep_check, ret, t_ret;

      ip = NULL;
      register_recovery = rep_check = 0;

      /* Initial configuration. */
      if ((ret = __env_config(dbenv, db_home, flags, mode)) != 0)
            return (ret);

      /*
       * Save the DB_ENV handle's configuration flags as set by user-called
       * configuration methods and the environment directory's DB_CONFIG
       * file.  If we use this DB_ENV structure to recover the existing
       * environment or to remove an environment we created after failure,
       * we'll restore the DB_ENV flags to these values.
       */
      orig_flags = dbenv->flags;

      /*
       * If we're going to register with the environment, that's the first
       * thing we do.
       */
      if (LF_ISSET(DB_REGISTER)) {
            if ((ret = __envreg_register(dbenv, &register_recovery)) != 0)
                  goto err;
            if (register_recovery) {
                  if (!LF_ISSET(DB_RECOVER)) {
                        __db_errx(dbenv,
          "The DB_RECOVER flag was not specified, and recovery is needed");
                        ret = DB_RUNRECOVERY;
                        goto err;
                  }
            } else
                  LF_CLR(DB_RECOVER);
      }

      /*
       * If we're doing recovery, destroy the environment so that we create
       * all the regions from scratch.  The major concern I have is if the
       * application stomps the environment with a rogue pointer.  We have
       * no way of detecting that, and we could be forced into a situation
       * where we start up and then crash, repeatedly.
       *
       * We do not check any flags like DB_PRIVATE before calling remove.
       * We don't care if the current environment was private or not, we
       * want to remove files left over for any reason, from any session.
       */
      if (LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL))
            if ((ret = __db_e_remove(dbenv, DB_FORCE)) != 0 ||
                (ret = __env_refresh(dbenv, orig_flags, 0)) != 0)
                  goto err;

      /* Convert the DB_ENV->open flags to internal flags. */
      if (LF_ISSET(DB_CREATE))
            F_SET(dbenv, DB_ENV_CREATE);
      if (LF_ISSET(DB_LOCKDOWN))
            F_SET(dbenv, DB_ENV_LOCKDOWN);
      if (LF_ISSET(DB_PRIVATE))
            F_SET(dbenv, DB_ENV_PRIVATE);
      if (LF_ISSET(DB_RECOVER_FATAL))
            F_SET(dbenv, DB_ENV_FATAL);
      if (LF_ISSET(DB_SYSTEM_MEM))
            F_SET(dbenv, DB_ENV_SYSTEM_MEM);
      if (LF_ISSET(DB_THREAD))
            F_SET(dbenv, DB_ENV_THREAD);

      /*
       * Flags saved in the init_flags field of the environment, representing
       * flags to DB_ENV->set_flags and DB_ENV->open that need to be set.
       */
#define     DB_INITENV_CDB          0x0001      /* DB_INIT_CDB */
#define     DB_INITENV_CDB_ALLDB    0x0002      /* DB_INIT_CDB_ALLDB */
#define     DB_INITENV_LOCK         0x0004      /* DB_INIT_LOCK */
#define     DB_INITENV_LOG          0x0008      /* DB_INIT_LOG */
#define     DB_INITENV_MPOOL  0x0010      /* DB_INIT_MPOOL */
#define     DB_INITENV_REP          0x0020      /* DB_INIT_REP */
#define     DB_INITENV_TXN          0x0040      /* DB_INIT_TXN */

      /*
       * Create/join the environment.  We pass in the flags of interest to
       * a thread subsequently joining an environment we create.  If we're
       * not the ones to create the environment, our flags will be updated
       * to match the existing environment.
       */
      init_flags = 0;
      if (LF_ISSET(DB_INIT_CDB))
            FLD_SET(init_flags, DB_INITENV_CDB);
      if (F_ISSET(dbenv, DB_ENV_CDB_ALLDB))
            FLD_SET(init_flags, DB_INITENV_CDB_ALLDB);
      if (LF_ISSET(DB_INIT_LOCK))
            FLD_SET(init_flags, DB_INITENV_LOCK);
      if (LF_ISSET(DB_INIT_LOG))
            FLD_SET(init_flags, DB_INITENV_LOG);
      if (LF_ISSET(DB_INIT_MPOOL))
            FLD_SET(init_flags, DB_INITENV_MPOOL);
      if (LF_ISSET(DB_INIT_REP))
            FLD_SET(init_flags, DB_INITENV_REP);
      if (LF_ISSET(DB_INIT_TXN))
            FLD_SET(init_flags, DB_INITENV_TXN);
      if ((ret = __db_e_attach(dbenv, &init_flags)) != 0)
            goto err;

      /*
       * __db_e_attach will return the saved init_flags field, which contains
       * the DB_INIT_* flags used when the environment was created.
       *
       * We may be joining an environment -- reset our flags to match the
       * ones in the environment.
       */
      if (FLD_ISSET(init_flags, DB_INITENV_CDB))
            LF_SET(DB_INIT_CDB);
      if (FLD_ISSET(init_flags, DB_INITENV_LOCK))
            LF_SET(DB_INIT_LOCK);
      if (FLD_ISSET(init_flags, DB_INITENV_LOG))
            LF_SET(DB_INIT_LOG);
      if (FLD_ISSET(init_flags, DB_INITENV_MPOOL))
            LF_SET(DB_INIT_MPOOL);
      if (FLD_ISSET(init_flags, DB_INITENV_REP))
            LF_SET(DB_INIT_REP);
      if (FLD_ISSET(init_flags, DB_INITENV_TXN))
            LF_SET(DB_INIT_TXN);
      if (FLD_ISSET(init_flags, DB_INITENV_CDB_ALLDB) &&
          (ret = __env_set_flags(dbenv, DB_CDB_ALLDB, 1)) != 0)
            goto err;

      /*
       * Save the flags matching the database environment: we'll replace
       * the argument flags with the flags corresponding to the existing,
       * underlying set of subsystems.
       */
      dbenv->open_flags = flags;

      /* Initialize for CDB product. */
      if (LF_ISSET(DB_INIT_CDB)) {
            LF_SET(DB_INIT_LOCK);
            F_SET(dbenv, DB_ENV_CDB);
      }

      /*
       * The DB_ENV structure has now been initialized.  Turn off further
       * use of the DB_ENV structure and most initialization methods, we're
       * about to act on the values we currently have.
       */
      F_SET(dbenv, DB_ENV_OPEN_CALLED);

      /*
       * Initialize the subsystems.
       *
       * Initialize the mutex regions first.  There's no ordering requirement,
       * but it's simpler to get this in place so we don't have to keep track
       * of mutexes for later allocation, once the mutex region is created we
       * can go ahead and do the allocation for real.
       */
      if ((ret = __mutex_open(dbenv)) != 0)
            goto err;

      /* __mutex_open creates the thread info region, enter it now. */
      ENV_ENTER(dbenv, ip);

      /*
       * Initialize the replication area next, so that we can lock out this
       * call if we're currently running recovery for replication.
       */
      if (LF_ISSET(DB_INIT_REP) && (ret = __rep_open(dbenv)) != 0)
            goto err;

      rep_check = IS_ENV_REPLICATED(dbenv) ? 1 : 0;
      if (rep_check && (ret = __env_rep_enter(dbenv, 0)) != 0)
            goto err;

      if (LF_ISSET(DB_INIT_MPOOL))
            if ((ret = __memp_open(dbenv)) != 0)
                  goto err;
      /*
       * Initialize the ciphering area prior to any running of recovery so
       * that we can initialize the keys, etc. before recovery.
       *
       * !!!
       * This must be after the mpool init, but before the log initialization
       * because log_open may attempt to run log_recover during its open.
       */
      if (LF_ISSET(DB_INIT_MPOOL | DB_INIT_LOG | DB_INIT_TXN) &&
          (ret = __crypto_region_init(dbenv)) != 0)
            goto err;

      /*
       * Transactions imply logging but do not imply locking.  While almost
       * all applications want both locking and logging, it would not be
       * unreasonable for a single threaded process to want transactions for
       * atomicity guarantees, but not necessarily need concurrency.
       */
      if (LF_ISSET(DB_INIT_LOG | DB_INIT_TXN))
            if ((ret = __log_open(dbenv)) != 0)
                  goto err;
      if (LF_ISSET(DB_INIT_LOCK))
            if ((ret = __lock_open(dbenv)) != 0)
                  goto err;

      if (LF_ISSET(DB_INIT_TXN)) {
            if ((ret = __txn_open(dbenv)) != 0)
                  goto err;

            /*
             * If the application is running with transactions, initialize
             * the function tables.
             */
            if ((ret = __env_init_rec(dbenv, DB_LOGVERSION)) != 0)
                  goto err;
      }

      /*
       * Initialize the DB list, and its mutex as necessary.  If the env
       * handle isn't free-threaded we don't need a mutex because there
       * will never be more than a single DB handle on the list.  If the
       * mpool wasn't initialized, then we can't ever open a DB handle.
       *
       * We also need to initialize the MT mutex as necessary, so do them
       * both.
       *
       * !!!
       * This must come after the __memp_open call above because if we are
       * recording mutexes for system resources, we will do it in the mpool
       * region for environments and db handles.  So, the mpool region must
       * already be initialized.
       */
      TAILQ_INIT(&dbenv->dblist);
      if (LF_ISSET(DB_INIT_MPOOL)) {
            if ((ret = __mutex_alloc(dbenv, MTX_ENV_DBLIST,
                DB_MUTEX_PROCESS_ONLY, &dbenv->mtx_dblist)) != 0)
                  goto err;
            if ((ret = __mutex_alloc(dbenv, MTX_TWISTER,
                DB_MUTEX_PROCESS_ONLY, &dbenv->mtx_mt)) != 0)
                  goto err;

            /* Register DB's pgin/pgout functions.  */
            if ((ret = __memp_register(
                dbenv, DB_FTYPE_SET, __db_pgin, __db_pgout)) != 0)
                  goto err;
      }

      /* Perform recovery for any previous run. */
      if (LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL) &&
          (ret = __db_apprec(dbenv, NULL, NULL, 1,
          LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL))) != 0)
            goto err;

      /*
       * If we've created the regions, are running with transactions, and did
       * not just run recovery, we need to log the fact that the transaction
       * IDs got reset.
       *
       * If we ran recovery, there may be prepared-but-not-yet-committed
       * transactions that need to be resolved.  Recovery resets the minimum
       * transaction ID and logs the reset if that's appropriate, so we
       * don't need to do anything here in the recover case.
       */
      infop = dbenv->reginfo;
      if (TXN_ON(dbenv) &&
          !F_ISSET(dbenv, DB_ENV_LOG_INMEMORY) &&
          F_ISSET(infop, REGION_CREATE) &&
          !LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL) &&
          (ret = __txn_reset(dbenv)) != 0)
            goto err;

      /* The database environment is ready for business. */
      if ((ret = __db_e_golive(dbenv)) != 0)
            goto err;

      if (rep_check)
            ret = __env_db_rep_exit(dbenv);

err:  ENV_LEAVE(dbenv, ip);

      if (ret != 0) {
            /*
             * If we fail after creating the regions, panic and remove them.
             *
             * !!!
             * No need to call __env_db_rep_exit, that work is done by the
             * calls to __env_refresh.
             */
            infop = dbenv->reginfo;
            if (infop != NULL && F_ISSET(infop, REGION_CREATE)) {
                  ret = __db_panic(dbenv, ret);

                  /* Refresh the DB_ENV so can use it to call remove. */
                  (void)__env_refresh(dbenv, orig_flags, rep_check);
                  (void)__db_e_remove(dbenv, DB_FORCE);
                  (void)__env_refresh(dbenv, orig_flags, 0);
            } else
                  (void)__env_refresh(dbenv, orig_flags, rep_check);
      }

      if (register_recovery) {
            /*
             * If recovery succeeded, release our exclusive lock, other
             * processes can now proceed.
             *
             * If recovery failed, unregister now and let another process
             * clean up.
             */
            if (ret == 0 && (t_ret = __envreg_xunlock(dbenv)) != 0)
                  ret = t_ret;
            if (ret != 0)
                  (void)__envreg_unregister(dbenv, 1);
      }

      return (ret);
}

/*
 * __env_remove --
 *    DB_ENV->remove.
 *
 * PUBLIC: int __env_remove __P((DB_ENV *, const char *, u_int32_t));
 */
int
__env_remove(dbenv, db_home, flags)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
{
      int ret, t_ret;

#undef      OKFLAGS
#define     OKFLAGS                                               \
      (DB_FORCE | DB_USE_ENVIRON | DB_USE_ENVIRON_ROOT)

      /* Validate arguments. */
      if ((ret = __db_fchk(dbenv, "DB_ENV->remove", flags, OKFLAGS)) != 0)
            return (ret);

      ENV_ILLEGAL_AFTER_OPEN(dbenv, "DB_ENV->remove");

      if ((ret = __env_config(dbenv, db_home, flags, 0)) != 0)
            return (ret);

      ret = __db_e_remove(dbenv, flags);

      if ((t_ret = __env_close(dbenv, 0)) != 0 && ret == 0)
            ret = t_ret;

      return (ret);
}

/*
 * __env_config --
 *    Argument-based initialization.
 *
 * PUBLIC: int __env_config __P((DB_ENV *, const char *, u_int32_t, int));
 */
int
__env_config(dbenv, db_home, flags, mode)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
      int mode;
{
      int ret;
      char *home, home_buf[DB_MAXPATHLEN];

      /*
       * Set the database home.
       *
       * Use db_home by default, this allows utilities to reasonably
       * override the environment either explicitly or by using a -h
       * option.  Otherwise, use the environment if it's permitted
       * and initialized.
       */
      home = (char *)db_home;
      if (home == NULL && (LF_ISSET(DB_USE_ENVIRON) ||
          (LF_ISSET(DB_USE_ENVIRON_ROOT) && __os_isroot()))) {
            home = home_buf;
            if ((ret = __os_getenv(
                dbenv, "DB_HOME", &home, sizeof(home_buf))) != 0)
                  return (ret);
            /*
             * home set to NULL if __os_getenv failed to find DB_HOME.
             */
      }
      if (home != NULL &&
          (ret = __os_strdup(dbenv, home, &dbenv->db_home)) != 0)
            return (ret);

      /* Default permissions are read-write for both owner and group. */
      dbenv->db_mode = mode == 0 ? __db_omode("rw-rw----") : mode;

      /* Read the DB_CONFIG file. */
      if ((ret = __env_read_db_config(dbenv)) != 0)
            return (ret);

      /*
       * If no temporary directory path was specified in the config file,
       * choose one.
       */
      if (dbenv->db_tmp_dir == NULL && (ret = __os_tmpdir(dbenv, flags)) != 0)
            return (ret);

      return (0);
}

/*
 * __env_close_pp --
 *    DB_ENV->close pre/post processor.
 *
 * PUBLIC: int __env_close_pp __P((DB_ENV *, u_int32_t));
 */
int
__env_close_pp(dbenv, flags)
      DB_ENV *dbenv;
      u_int32_t flags;
{
      DB_THREAD_INFO *ip;
      int rep_check, ret, t_ret;

      ret = 0;

      PANIC_CHECK(dbenv);

      ENV_ENTER(dbenv, ip);
      /*
       * Validate arguments, but as a DB_ENV handle destructor, we can't
       * fail.
       */
      if (flags != 0 &&
          (t_ret = __db_ferr(dbenv, "DB_ENV->close", 0)) != 0 && ret == 0)
            ret = t_ret;

      rep_check = IS_ENV_REPLICATED(dbenv) ? 1 : 0;
      if (rep_check) {
#ifdef HAVE_REPLICATION_THREADS
            /*
             * Shut down Replication Manager threads first of all.  This
             * must be done before __env_rep_enter to avoid a deadlock that
             * could occur if repmgr's background threads try to do a rep
             * operation that needs __rep_lockout.
             */
            if ((t_ret = __repmgr_close(dbenv)) != 0 && ret == 0)
                  ret = t_ret;
#endif
            if ((t_ret = __env_rep_enter(dbenv, 0)) != 0 && ret == 0)
                  ret = t_ret;
      }

      if ((t_ret = __env_close(dbenv, rep_check)) != 0 && ret == 0)
            ret = t_ret;

      /* Don't ENV_LEAVE as we have already detached from the region. */
      return (ret);
}

/*
 * __env_close --
 *    DB_ENV->close.
 *
 * PUBLIC: int __env_close __P((DB_ENV *, int));
 */
int
__env_close(dbenv, rep_check)
      DB_ENV *dbenv;
      int rep_check;
{
      int ret, t_ret;
      char **p;

      ret = 0;

      /*
       * Before checking the reference count, we have to see if we were in
       * the middle of restoring transactions and need to close the open
       * files.
       */
      if (TXN_ON(dbenv) && (t_ret = __txn_preclose(dbenv)) != 0 && ret == 0)
            ret = t_ret;

#ifdef HAVE_REPLICATION
      if ((t_ret = __rep_close(dbenv)) != 0 && ret == 0)
            ret = t_ret;
#endif

      /*
       * Detach from the regions and undo the allocations done by
       * DB_ENV->open.
       */
      if ((t_ret = __env_refresh(dbenv, 0, rep_check)) != 0 && ret == 0)
            ret = t_ret;

#ifdef HAVE_CRYPTO
      /*
       * Crypto comes last, because higher level close functions need
       * cryptography.
       */
      if ((t_ret = __crypto_dbenv_close(dbenv)) != 0 && ret == 0)
            ret = t_ret;
#endif
      /* If we're registered, clean up. */
      if (dbenv->registry != NULL) {
            (void)__envreg_unregister(dbenv, 0);
            dbenv->registry = NULL;
      }

      /* Release any string-based configuration parameters we've copied. */
      if (dbenv->db_log_dir != NULL)
            __os_free(dbenv, dbenv->db_log_dir);
      dbenv->db_log_dir = NULL;
      if (dbenv->db_tmp_dir != NULL)
            __os_free(dbenv, dbenv->db_tmp_dir);
      dbenv->db_tmp_dir = NULL;
      if (dbenv->db_data_dir != NULL) {
            for (p = dbenv->db_data_dir; *p != NULL; ++p)
                  __os_free(dbenv, *p);
            __os_free(dbenv, dbenv->db_data_dir);
            dbenv->db_data_dir = NULL;
            dbenv->data_next = 0;
      }
      if (dbenv->db_home != NULL) {
            __os_free(dbenv, dbenv->db_home);
            dbenv->db_home = NULL;
      }

      /* Discard the structure. */
      __db_env_destroy(dbenv);

      return (ret);
}

/*
 * __env_refresh --
 *    Refresh the DB_ENV structure.
 */
static int
__env_refresh(dbenv, orig_flags, rep_check)
      DB_ENV *dbenv;
      u_int32_t orig_flags;
      int rep_check;
{
      DB *ldbp;
      DB_THREAD_INFO *ip;
      int ret, t_ret;

      ret = 0;

      /*
       * Release resources allocated by DB_ENV->open, and return it to the
       * state it was in just before __env_open was called.  (This means
       * state set by pre-open configuration functions must be preserved.)
       *
       * Refresh subsystems, in the reverse order they were opened (txn
       * must be first, it may want to discard locks and flush the log).
       *
       * !!!
       * Note that these functions, like all of __env_refresh, only undo
       * the effects of __env_open.  Functions that undo work done by
       * db_env_create or by a configuration function should go in
       * __env_close.
       */
      if (TXN_ON(dbenv) &&
          (t_ret = __txn_dbenv_refresh(dbenv)) != 0 && ret == 0)
            ret = t_ret;

      if (LOGGING_ON(dbenv) &&
          (t_ret = __log_dbenv_refresh(dbenv)) != 0 && ret == 0)
            ret = t_ret;

      /*
       * Locking should come after logging, because closing log results
       * in files closing which may require locks being released.
       */
      if (LOCKING_ON(dbenv)) {
            if (!F_ISSET(dbenv, DB_ENV_THREAD) &&
                dbenv->env_lref != NULL && (t_ret = __lock_id_free(dbenv,
                ((DB_LOCKER *)dbenv->env_lref)->id)) != 0 && ret == 0)
                  ret = t_ret;
            dbenv->env_lref = NULL;

            if ((t_ret = __lock_dbenv_refresh(dbenv)) != 0 && ret == 0)
                  ret = t_ret;
      }

      /*
       * Discard DB list and its mutex.
       * Discard the MT mutex.
       *
       * !!!
       * This must be done before we close the mpool region because we
       * may have allocated the DB handle mutex in the mpool region.
       * It must be done *after* we close the log region, though, because
       * we close databases and try to acquire the mutex when we close
       * log file handles.  Ick.
       */
      if (dbenv->db_ref != 0) {
            __db_errx(dbenv,
                "Database handles still open at environment close");
            TAILQ_FOREACH(ldbp, &dbenv->dblist, dblistlinks)
                  __db_errx(dbenv, "Open database handle: %s%s%s",
                      ldbp->fname == NULL ? "unnamed" : ldbp->fname,
                      ldbp->dname == NULL ? "" : "/",
                      ldbp->dname == NULL ? "" : ldbp->dname);
            if (ret == 0)
                  ret = EINVAL;
      }
      TAILQ_INIT(&dbenv->dblist);

      if ((t_ret = __mutex_free(dbenv, &dbenv->mtx_dblist)) != 0 && ret == 0)
            ret = t_ret;
      if ((t_ret = __mutex_free(dbenv, &dbenv->mtx_mt)) != 0 && ret == 0)
            ret = t_ret;

      if (dbenv->mt != NULL) {
            __os_free(dbenv, dbenv->mt);
            dbenv->mt = NULL;
      }

      if (MPOOL_ON(dbenv)) {
            /*
             * If it's a private environment, flush the contents to disk.
             * Recovery would have put everything back together, but it's
             * faster and cleaner to flush instead.
             */
            if (F_ISSET(dbenv, DB_ENV_PRIVATE) &&
                (t_ret = __memp_sync(dbenv, NULL)) != 0 && ret == 0)
                  ret = t_ret;
            if ((t_ret = __memp_dbenv_refresh(dbenv)) != 0 && ret == 0)
                  ret = t_ret;
      }

      /*
       * If we're included in a shared replication handle count, this
       * is our last chance to decrement that count.
       *
       * !!!
       * We can't afford to do anything dangerous after we decrement the
       * handle count, of course, as replication may be proceeding with
       * client recovery.  However, since we're discarding the regions
       * as soon as we drop the handle count, there's little opportunity
       * to do harm.
       */
      if (rep_check && (t_ret = __env_db_rep_exit(dbenv)) != 0 && ret == 0)
            ret = t_ret;

      /*
       * Detach from the region.
       *
       * Must come after we call __env_db_rep_exit above.
       */
      if (REP_ON(dbenv))
            __rep_dbenv_refresh(dbenv);

      /*
       * Mark the thread as out of the env before we get rid of the handles
       * needed to do so.
       */
      if (dbenv->thr_hashtab != NULL &&
          (t_ret = __env_set_state(dbenv, &ip, THREAD_OUT)) != 0 && ret == 0)
            ret = t_ret;

      if (MUTEX_ON(dbenv) &&
          (t_ret = __mutex_dbenv_refresh(dbenv)) != 0 && ret == 0)
            ret = t_ret;

      if (dbenv->reginfo != NULL) {
            if ((t_ret = __db_e_detach(dbenv, 0)) != 0 && ret == 0)
                  ret = t_ret;
            /*
             * !!!
             * Don't free dbenv->reginfo or set the reference to NULL,
             * that was done by __db_e_detach().
             */
      }

      if (dbenv->mutex_iq != NULL) {
            __os_free(dbenv, dbenv->mutex_iq);
            dbenv->mutex_iq = NULL;
      }

      if (dbenv->recover_dtab != NULL) {
            __os_free(dbenv, dbenv->recover_dtab);
            dbenv->recover_dtab = NULL;
            dbenv->recover_dtab_size = 0;
      }

      dbenv->flags = orig_flags;

      return (ret);
}

#define     DB_ADDSTR(add) {                                \
      /*                                              \
       * The string might be NULL or zero-length, and the p[-1]   \
       * might indirect to before the beginning of our buffer.    \
       */                                             \
      if ((add) != NULL && (add)[0] != '\0') {              \
            /* If leading slash, start over. */             \
            if (__os_abspath(add)) {                        \
                  p = str;                            \
                  slash = 0;                          \
            }                                         \
            /* Append to the current string. */             \
            len = strlen(add);                              \
            if (slash)                                \
                  *p++ = PATH_SEPARATOR[0];                 \
            memcpy(p, add, len);                            \
            p += len;                                 \
            slash = strchr(PATH_SEPARATOR, p[-1]) == NULL;        \
      }                                               \
}

/*
 * __env_get_open_flags
 *    Retrieve the flags passed to DB_ENV->open.
 *
 * PUBLIC: int __env_get_open_flags __P((DB_ENV *, u_int32_t *));
 */
int
__env_get_open_flags(dbenv, flagsp)
      DB_ENV *dbenv;
      u_int32_t *flagsp;
{
      ENV_ILLEGAL_BEFORE_OPEN(dbenv, "DB_ENV->get_open_flags");

      *flagsp = dbenv->open_flags;
      return (0);
}

/*
 * __db_appname --
 *    Given an optional DB environment, directory and file name and type
 *    of call, build a path based on the DB_ENV->open rules, and return
 *    it in allocated space.
 *
 * PUBLIC: int __db_appname __P((DB_ENV *, APPNAME,
 * PUBLIC:    const char *, u_int32_t, DB_FH **, char **));
 */
int
__db_appname(dbenv, appname, file, tmp_oflags, fhpp, namep)
      DB_ENV *dbenv;
      APPNAME appname;
      const char *file;
      u_int32_t tmp_oflags;
      DB_FH **fhpp;
      char **namep;
{
      enum { TRY_NOTSET, TRY_DATA_DIR, TRY_ENV_HOME, TRY_CREATE } try_state;
      size_t len, str_len;
      int data_entry, ret, slash, tmp_create;
      const char *a, *b;
      char *p, *str;

      try_state = TRY_NOTSET;
      a = b = NULL;
      data_entry = 0;
      tmp_create = 0;

      /*
       * We don't return a name when creating temporary files, just a file
       * handle.  Default to an error now.
       */
      if (fhpp != NULL)
            *fhpp = NULL;
      if (namep != NULL)
            *namep = NULL;

      /*
       * Absolute path names are never modified.  If the file is an absolute
       * path, we're done.
       */
      if (file != NULL && __os_abspath(file))
            return (__os_strdup(dbenv, file, namep));

      /* Everything else is relative to the environment home. */
      if (dbenv != NULL)
            a = dbenv->db_home;

retry:      /*
       * DB_APP_NONE:
       *      DB_HOME/file
       * DB_APP_DATA:
       *      DB_HOME/DB_DATA_DIR/file
       * DB_APP_LOG:
       *      DB_HOME/DB_LOG_DIR/file
       * DB_APP_TMP:
       *      DB_HOME/DB_TMP_DIR/<create>
       */
      switch (appname) {
      case DB_APP_NONE:
            break;
      case DB_APP_DATA:
            if (dbenv == NULL || dbenv->db_data_dir == NULL) {
                  try_state = TRY_CREATE;
                  break;
            }

            /*
             * First, step through the data_dir entries, if any, looking
             * for the file.
             */
            if ((b = dbenv->db_data_dir[data_entry]) != NULL) {
                  ++data_entry;
                  try_state = TRY_DATA_DIR;
                  break;
            }

            /* Second, look in the environment home directory. */
            if (try_state != TRY_ENV_HOME) {
                  try_state = TRY_ENV_HOME;
                  break;
            }

            /* Third, try creation in the first data_dir entry. */
            try_state = TRY_CREATE;
            b = dbenv->db_data_dir[0];
            break;
      case DB_APP_LOG:
            if (dbenv != NULL)
                  b = dbenv->db_log_dir;
            break;
      case DB_APP_TMP:
            if (dbenv != NULL)
                  b = dbenv->db_tmp_dir;
            tmp_create = 1;
            break;
      }

      len =
          (a == NULL ? 0 : strlen(a) + 1) +
          (b == NULL ? 0 : strlen(b) + 1) +
          (file == NULL ? 0 : strlen(file) + 1);

      /*
       * Allocate space to hold the current path information, as well as any
       * temporary space that we're going to need to create a temporary file
       * name.
       */
#define     DB_TRAIL    "BDBXXXXX"
      str_len = len + sizeof(DB_TRAIL) + 10;
      if ((ret = __os_malloc(dbenv, str_len, &str)) != 0)
            return (ret);

      slash = 0;
      p = str;
      DB_ADDSTR(a);
      DB_ADDSTR(b);
      DB_ADDSTR(file);
      *p = '\0';

      /*
       * If we're opening a data file, see if it exists.  If it does,
       * return it, otherwise, try and find another one to open.
       */
      if (appname == DB_APP_DATA &&
          __os_exists(dbenv, str, NULL) != 0 && try_state != TRY_CREATE) {
            __os_free(dbenv, str);
            b = NULL;
            goto retry;
      }

      /* Create the file if so requested. */
      if (tmp_create &&
          (ret = __db_tmp_open(dbenv, tmp_oflags, str, fhpp)) != 0) {
            __os_free(dbenv, str);
            return (ret);
      }

      if (namep == NULL)
            __os_free(dbenv, str);
      else
            *namep = str;
      return (0);
}

/*
 * __db_tmp_open --
 *    Create a temporary file.
 */
static int
__db_tmp_open(dbenv, tmp_oflags, path, fhpp)
      DB_ENV *dbenv;
      u_int32_t tmp_oflags;
      char *path;
      DB_FH **fhpp;
{
      pid_t pid;
      int filenum, i, isdir, ret;
      char *firstx, *trv;

      /*
       * Check the target directory; if you have six X's and it doesn't
       * exist, this runs for a *very* long time.
       */
      if ((ret = __os_exists(dbenv, path, &isdir)) != 0) {
            __db_err(dbenv, ret, "%s", path);
            return (ret);
      }
      if (!isdir) {
            __db_err(dbenv, EINVAL, "%s", path);
            return (EINVAL);
      }

      /* Build the path. */
      (void)strncat(path, PATH_SEPARATOR, 1);
      (void)strcat(path, DB_TRAIL);

      /* Replace the X's with the process ID (in decimal). */
      __os_id(dbenv, &pid, NULL);
      for (trv = path + strlen(path); *--trv == 'X'; pid /= 10)
            *trv = '0' + (u_char)(pid % 10);
      firstx = trv + 1;

      /* Loop, trying to open a file. */
      for (filenum = 1;; filenum++) {
            if ((ret = __os_open(dbenv, path,
                tmp_oflags | DB_OSO_CREATE | DB_OSO_EXCL | DB_OSO_TEMP,
                __db_omode(OWNER_RW), fhpp)) == 0)
                  return (0);

            /*
             * !!!:
             * If we don't get an EEXIST error, then there's something
             * seriously wrong.  Unfortunately, if the implementation
             * doesn't return EEXIST for O_CREAT and O_EXCL regardless
             * of other possible errors, we've lost.
             */
            if (ret != EEXIST) {
                  __db_err(dbenv, ret, "temporary open: %s", path);
                  return (ret);
            }

            /*
             * Generate temporary file names in a backwards-compatible way.
             * If pid == 12345, the result is:
             *   <path>/DB12345 (tried above, the first time through).
             *   <path>/DBa2345 ...  <path>/DBz2345
             *   <path>/DBaa345 ...  <path>/DBaz345
             *   <path>/DBba345, and so on.
             *
             * XXX
             * This algorithm is O(n**2) -- that is, creating 100 temporary
             * files requires 5,000 opens, creating 1000 files requires
             * 500,000.  If applications open a lot of temporary files, we
             * could improve performance by switching to timestamp-based
             * file names.
             */
            for (i = filenum, trv = firstx; i > 0; i = (i - 1) / 26)
                  if (*trv++ == '\0')
                        return (EINVAL);

            for (i = filenum; i > 0; i = (i - 1) / 26)
                  *--trv = 'a' + ((i - 1) % 26);
      }
      /* NOTREACHED */
}

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