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Sourcecode: db4.3 version File versions

env_open.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2004
 *    Sleepycat Software.  All rights reserved.
 *
 * $Id: env_open.c,v 11.177 2004/07/17 18:55:08 ubell Exp $
 */

#include "db_config.h"

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

#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/crypto.h"
#include "dbinc/db_page.h"
#include "dbinc/db_shash.h"
#include "dbinc/btree.h"
#include "dbinc/hash.h"
#include "dbinc/fop.h"
#include "dbinc/lock.h"
#include "dbinc/log.h"
#include "dbinc/mp.h"
#include "dbinc/qam.h"
#include "dbinc/txn.h"

static int __db_parse __P((DB_ENV *, char *));
static int __db_tmp_open __P((DB_ENV *, u_int32_t, char *, DB_FH **));
static int __dbenv_config __P((DB_ENV *, const char *, u_int32_t));
static int __dbenv_refresh __P((DB_ENV *, u_int32_t, int));
static int __dbenv_remove_int __P((DB_ENV *, const char *, u_int32_t));

/*
 * 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);
}

/*
 * __dbenv_open --
 *    DB_ENV->open.
 *
 * PUBLIC: int __dbenv_open __P((DB_ENV *, const char *, u_int32_t, int));
 */
int
__dbenv_open(dbenv, db_home, flags, mode)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
      int mode;
{
      DB_MPOOL *dbmp;
      u_int32_t init_flags, orig_flags;
      int rep_check, ret;

      orig_flags = dbenv->flags;
      rep_check = 0;

#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_JOINENV |    \
      DB_LOCKDOWN | DB_PRIVATE | DB_RECOVER | DB_RECOVER_FATAL |  \
      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)

      /*
       * 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 */

      if ((ret = __db_fchk(dbenv, "DB_ENV->open", flags, OKFLAGS)) != 0)
            return (ret);
      if (LF_ISSET(DB_INIT_CDB) &&
          (ret = __db_fchk(dbenv, "DB_ENV->open", flags, OKFLAGS_CDB)) != 0)
            return (ret);
      if ((ret = __db_fcchk(dbenv,
          "DB_ENV->open", flags, DB_PRIVATE, DB_SYSTEM_MEM)) != 0)
            return (ret);
      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_JOINENV,
          DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL |
          DB_INIT_REP | DB_INIT_TXN |
          DB_PRIVATE | DB_RECOVER | DB_RECOVER_FATAL)) != 0)
            return (ret);
      if (LF_ISSET(DB_INIT_REP) && !LF_ISSET(DB_INIT_TXN)) {
            __db_err(dbenv, "Replication requires transaction support");
            return (EINVAL);
      }
      if (LF_ISSET(DB_INIT_REP) && !LF_ISSET(DB_INIT_LOCK)) {
            __db_err(dbenv, "Replication requires locking support");
            return (EINVAL);
      }
      if (LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL) && !LF_ISSET(DB_INIT_TXN)) {
            __db_err(dbenv, "Recovery requires transaction support");
            return (EINVAL);
      }

      /*
       * 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.
       */
#ifdef HAVE_MUTEX_THREAD_ONLY
      if (!LF_ISSET(DB_PRIVATE)) {
            __db_err(dbenv,
    "Berkeley DB library configured to support only private environments");
            return (EINVAL);
      }
#endif

      /*
       * If we're doing recovery, destroy the environment so that we create
       * all the regions from scratch.  I'd like to reuse already created
       * regions, but that's hard.  We would have to create the environment
       * region from scratch, at least, as we have no way of knowing if its
       * linked lists are corrupted.
       *
       * I suppose we could set flags while modifying those links, but that
       * is going to be difficult to get right.  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.
       *
       * Note that 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 just want to nail any files that are left-over for whatever
       * reason, from whatever session.
       */
      if (LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL))
            if ((ret = __dbenv_remove_int(dbenv, db_home, DB_FORCE)) != 0 ||
                (ret = __dbenv_refresh(dbenv, orig_flags, 0)) != 0)
                  return (ret);

      /* Initialize the DB_ENV structure. */
      if ((ret = __dbenv_config(dbenv, db_home, flags)) != 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);

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

      /*
       * Create/join the environment.  We pass in the flags that will be of
       * interest to an environment joining later; if we're not the ones to
       * do the create, we pull out whatever has been stored.
       */
      init_flags = 0;
      if (LF_ISSET(DB_INIT_CDB))
            FLD_SET(init_flags, DB_INITENV_CDB);
      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 (F_ISSET(dbenv, DB_ENV_CDB_ALLDB))
            FLD_SET(init_flags, DB_INITENV_CDB_ALLDB);
      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.
       *
       * Check if existing environment flags conflict with our flags.
       */
      if (LF_ISSET(DB_INIT_CDB) && FLD_ISSET(init_flags, DB_INITENV_TXN)) {
            __db_err(dbenv,
                "Concurrent Data Store incompatible with environment");
            ret = EINVAL;
            goto err;
      }
      if (LF_ISSET(DB_INIT_TXN) && FLD_ISSET(init_flags, DB_INITENV_CDB)) {
            __db_err(dbenv,
                "Transactional Data Store incompatible with environment");
            ret = EINVAL;
            goto err;
      }

      /* If we're joining the environment, find out what we're joining. */
      if (LF_ISSET(DB_JOINENV)) {
            LF_CLR(DB_JOINENV);
            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 = __dbenv_set_flags(dbenv, DB_CDB_ALLDB, 1)) != 0)
                  goto err;
      }

      /*
       * Save the flags passed to create the DB_ENV->open, that is, we've
       * now replaced flags like DB_JOINENV with the flags responsible for
       * the 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);
      }

      /*
       * Initialize the subsystems.
       *
       * Initialize the replication area first, 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)
            __env_rep_enter(dbenv);

      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 = __bam_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __crdel_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __db_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __dbreg_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __fop_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __ham_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __qam_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 0)
                  goto err;
            if ((ret = __txn_init_recover(dbenv, &dbenv->recover_dtab,
                &dbenv->recover_dtab_size)) != 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.  If we error, __dbenv_refresh() will clean up.
       *
       * !!!
       * 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.
       */
      LIST_INIT(&dbenv->dblist);
      if (LF_ISSET(DB_INIT_MPOOL)) {
            dbmp = dbenv->mp_handle;
            if (F_ISSET(dbenv, DB_ENV_THREAD)) {
                  if ((ret = __db_mutex_setup(
                      dbenv, dbmp->reginfo, &dbenv->dblist_mutexp,
                      MUTEX_ALLOC | MUTEX_THREAD)) != 0)
                        goto err;
                  if ((ret = __db_mutex_setup(
                      dbenv, dbmp->reginfo, &dbenv->mt_mutexp,
                      MUTEX_ALLOC | MUTEX_THREAD)) != 0)
                        goto err;
            }
            /* Register DB's pgin/pgout functions.  */
            if ((ret = __memp_register(
                dbenv, DB_FTYPE_SET, __db_pgin, __db_pgout)) != 0)
                  return (ret);
      }

      /* 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.
       */
      if (TXN_ON(dbenv) &&
          !F_ISSET(dbenv, DB_ENV_LOG_INMEMORY) &&
          F_ISSET((REGINFO *)dbenv->reginfo, REGION_CREATE) &&
          !LF_ISSET(DB_RECOVER | DB_RECOVER_FATAL) &&
          (ret = __txn_reset(dbenv)) != 0)
            goto err;

      if (rep_check)
            __env_db_rep_exit(dbenv);

      return (0);

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

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

      return (ret);
}

/*
 * __dbenv_remove --
 *    DB_ENV->remove.
 *
 * PUBLIC: int __dbenv_remove __P((DB_ENV *, const char *, u_int32_t));
 */
int
__dbenv_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");

      ret = __dbenv_remove_int(dbenv, db_home, flags);

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

      return (ret);
}

/*
 * __dbenv_remove_int --
 *    Discard an environment, internal version.
 */
static int
__dbenv_remove_int(dbenv, db_home, flags)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
{
      int ret;

      /* Initialize the DB_ENV structure. */
      if ((ret = __dbenv_config(dbenv, db_home, flags)) != 0)
            return (ret);

      /* Remove the environment. */
      return (__db_e_remove(dbenv, flags));
}

/*
 * __dbenv_config --
 *    Minor initialization of the DB_ENV structure, read the DB_CONFIG file.
 */
static int
__dbenv_config(dbenv, db_home, flags)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
{
      FILE *fp;
      int ret;
      char *p, buf[256];

      /*
       * Set the database home.  Do this before calling __db_appname,
       * it uses the home directory.
       */
      if ((ret = __db_home(dbenv, db_home, flags)) != 0)
            return (ret);

      /* Parse the config file. */
      p = NULL;
      if ((ret =
          __db_appname(dbenv, DB_APP_NONE, "DB_CONFIG", 0, NULL, &p)) != 0)
            return (ret);
      if (p == NULL)
            fp = NULL;
      else {
            fp = fopen(p, "r");
            __os_free(dbenv, p);
      }

      if (fp != NULL) {
            while (fgets(buf, sizeof(buf), fp) != NULL) {
                  if ((p = strchr(buf, '\n')) != NULL)
                        *p = '\0';
                  else if (strlen(buf) + 1 == sizeof(buf)) {
                        __db_err(dbenv, "DB_CONFIG: line too long");
                        (void)fclose(fp);
                        return (EINVAL);
                  }
                  if (buf[0] == '\0' ||
                      buf[0] == '#' || isspace((int)buf[0]))
                        continue;

                  if ((ret = __db_parse(dbenv, buf)) != 0) {
                        (void)fclose(fp);
                        return (ret);
                  }
            }
            (void)fclose(fp);
      }

      /*
       * 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);

      /* Flag that the DB_ENV structure has been initialized. */
      F_SET(dbenv, DB_ENV_OPEN_CALLED);

      return (0);
}

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

      ret = 0;

      PANIC_CHECK(dbenv);

      /*
       * 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)
            __env_rep_enter(dbenv);

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

      return (ret);
}

/*
 * __dbenv_close --
 *    DB_ENV->close.
 *
 * PUBLIC: int __dbenv_close __P((DB_ENV *, int));
 */
int
__dbenv_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;

      if (REP_ON(dbenv) &&
          (t_ret = __rep_preclose(dbenv, 1)) != 0 && ret == 0)
            ret = t_ret;

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

      /* Do per-subsystem close. */
      if ((t_ret = __lock_dbenv_close(dbenv)) != 0 && ret == 0)
            ret = t_ret;

      if ((t_ret = __rep_dbenv_close(dbenv)) != 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

      /* Release any string-based configuration parameters we've copied. */
      if (dbenv->db_log_dir != NULL)
            __os_free(dbenv, dbenv->db_log_dir);
      if (dbenv->db_tmp_dir != NULL)
            __os_free(dbenv, dbenv->db_tmp_dir);
      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);
      }

      /* Discard the structure. */
      memset(dbenv, CLEAR_BYTE, sizeof(DB_ENV));
      __os_free(NULL, dbenv);

      return (ret);
}

/*
 * __dbenv_refresh --
 *    Refresh the DB_ENV structure, releasing resources allocated by
 * DB_ENV->open, and returning it to the state it was in just before
 * open was called.  (Note that this means that any state set by
 * pre-open configuration functions must be preserved.)
 */
static int
__dbenv_refresh(dbenv, orig_flags, rep_check)
      DB_ENV *dbenv;
      u_int32_t orig_flags;
      int rep_check;
{
      DB *ldbp;
      DB_MPOOL *dbmp;
      int ret, t_ret;

      dbmp = dbenv->mp_handle;
      ret = 0;

      /*
       * 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 __dbenv_refresh, only undo
       * the effects of __dbenv_open.  Functions that undo work done by
       * db_env_create or by a configuration function should go in
       * __dbenv_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_lid != DB_LOCK_INVALIDID &&
                (t_ret = __lock_id_free(dbenv, dbenv->env_lid)) != 0 &&
                ret == 0)
                  ret = t_ret;
            dbenv->env_lid = DB_LOCK_INVALIDID;

            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_err(dbenv, "Database handles remain at environment close");
            for (ldbp = LIST_FIRST(&dbenv->dblist);
                ldbp != NULL; ldbp = LIST_NEXT(ldbp, dblistlinks))
                  __db_err(dbenv, "Open database handle: %s%s%s",
                      ldbp->fname, ldbp->dname == NULL ? "" : "/",
                      ldbp->dname == NULL ? "" : ldbp->dname);
            if (ret == 0)
                  ret = EINVAL;
      }
      LIST_INIT(&dbenv->dblist);
      if (dbenv->dblist_mutexp != NULL)
            __db_mutex_free(dbenv, dbmp->reginfo, dbenv->dblist_mutexp);
      if (dbenv->mt_mutexp != NULL)
            __db_mutex_free(dbenv, dbmp->reginfo, dbenv->mt_mutexp);
      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)
            __env_db_rep_exit(dbenv);

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

      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().
             */
      }

      /* Undo changes and allocations done by __dbenv_open. */
      if (dbenv->db_home != NULL) {
            __os_free(dbenv, dbenv->db_home);
            dbenv->db_home = NULL;
      }

      dbenv->open_flags = 0;
      dbenv->db_mode = 0;

      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;        \
      }                                               \
}

/*
 * __dbenv_get_open_flags
 *    Retrieve the flags passed to DB_ENV->open.
 *
 * PUBLIC: int __dbenv_get_open_flags __P((DB_ENV *, u_int32_t *));
 */
int
__dbenv_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;
{
      size_t len, str_len;
      int data_entry, ret, slash, tmp_create;
      const char *a, *b;
      char *p, *str;

      a = b = NULL;
      data_entry = -1;
      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 &&
                (b = dbenv->db_data_dir[++data_entry]) == NULL) {
                  data_entry = -1;
                  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 (__os_exists(str, NULL) != 0 && data_entry != -1) {
            __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_home --
 *    Find the database home.
 *
 * PUBLIC:  int __db_home __P((DB_ENV *, const char *, u_int32_t));
 */
int
__db_home(dbenv, db_home, flags)
      DB_ENV *dbenv;
      const char *db_home;
      u_int32_t flags;
{
      const char *p;

      /*
       * 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.
       */
      if ((p = db_home) == NULL &&
          (LF_ISSET(DB_USE_ENVIRON) ||
          (LF_ISSET(DB_USE_ENVIRON_ROOT) && __os_isroot())) &&
          (p = getenv("DB_HOME")) != NULL && p[0] == '\0') {
            __db_err(dbenv, "illegal DB_HOME environment variable");
            return (EINVAL);
      }

      return (p == NULL ? 0 : __os_strdup(dbenv, p, &dbenv->db_home));
}

#define     __DB_OVFL(v, max)                               \
      if (v > max) {                                        \
            __v = v;                                  \
            __max = max;                                    \
            goto toobig;                                    \
      }

/*
 * __db_parse --
 *    Parse a single NAME VALUE pair.
 */
static int
__db_parse(dbenv, s)
      DB_ENV *dbenv;
      char *s;
{
      u_long __max, __v, v1, v2, v3;
      u_int32_t flags;
      char *name, *p, *value, v4;

      /*
       * !!!
       * The constant 40 is hard-coded into format arguments to sscanf
       * below, it can't be changed here without changing it there, too.
       * The additional bytes are for a trailing nul byte and because we
       * are reading user input -- I don't want to risk any off-by-ones.
       */
      char arg[40 + 5];

      /*
       * Name/value pairs are parsed as two white-space separated strings.
       * Leading and trailing white-space is trimmed from the value, but
       * it may contain embedded white-space.  Note: we use the isspace(3)
       * macro because it's more portable, but that means that you can use
       * characters like form-feed to separate the strings.
       */
      name = s;
      for (p = name; *p != '\0' && !isspace((int)*p); ++p)
            ;
      if (*p == '\0' || p == name)
            goto illegal;
      *p = '\0';
      for (++p; isspace((int)*p); ++p)
            ;
      if (*p == '\0')
            goto illegal;
      value = p;
      for (++p; *p != '\0'; ++p)
            ;
      for (--p; isspace((int)*p); --p)
            ;
      ++p;
      if (p == value) {
illegal:    __db_err(dbenv, "mis-formatted name-value pair: %s", s);
            return (EINVAL);
      }
      *p = '\0';

      if (!strcasecmp(name, "set_cachesize")) {
            if (sscanf(value, "%lu %lu %lu %c", &v1, &v2, &v3, &v4) != 3)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            __DB_OVFL(v2, UINT32_MAX);
            __DB_OVFL(v3, 10000);
            return (__memp_set_cachesize(
                dbenv, (u_int32_t)v1, (u_int32_t)v2, (int)v3));
      }

      if (!strcasecmp(name, "set_data_dir") ||
          !strcasecmp(name, "db_data_dir"))           /* Compatibility. */
            return (__dbenv_set_data_dir(dbenv, value));

      if (!strcasecmp(name, "set_intermediate_dir")) {/* Undocumented. */
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
#ifdef INT_MAX
            __DB_OVFL(v1, INT_MAX);
#endif
            return (__dbenv_set_intermediate_dir(dbenv, (int)v1, 0));
      }

      if (!strcasecmp(name, "set_flags")) {
            if (sscanf(value, "%40s %c", arg, &v4) != 1)
                  goto badarg;

            if (!strcasecmp(value, "db_auto_commit"))
                  return (__dbenv_set_flags(dbenv, DB_AUTO_COMMIT, 1));
            if (!strcasecmp(value, "db_cdb_alldb"))
                  return (__dbenv_set_flags(dbenv, DB_CDB_ALLDB, 1));
            if (!strcasecmp(value, "db_direct_db"))
                  return (__dbenv_set_flags(dbenv, DB_DIRECT_DB, 1));
            if (!strcasecmp(value, "db_direct_log"))
                  return (__dbenv_set_flags(dbenv, DB_DIRECT_LOG, 1));
            if (!strcasecmp(value, "db_dsync_log"))
                  return (__dbenv_set_flags(dbenv, DB_DSYNC_LOG, 1));
            if (!strcasecmp(value, "db_log_autoremove"))
                  return (__dbenv_set_flags(dbenv, DB_LOG_AUTOREMOVE, 1));
            if (!strcasecmp(value, "db_log_inmemory"))
                  return (__dbenv_set_flags(dbenv, DB_LOG_INMEMORY, 1));
            if (!strcasecmp(value, "db_nolocking"))
                  return (__dbenv_set_flags(dbenv, DB_NOLOCKING, 1));
            if (!strcasecmp(value, "db_nommap"))
                  return (__dbenv_set_flags(dbenv, DB_NOMMAP, 1));
            if (!strcasecmp(value, "db_nopanic"))
                  return (__dbenv_set_flags(dbenv, DB_NOPANIC, 1));
            if (!strcasecmp(value, "db_overwrite"))
                  return (__dbenv_set_flags(dbenv, DB_OVERWRITE, 1));
            if (!strcasecmp(value, "db_region_init"))
                  return (__dbenv_set_flags(dbenv, DB_REGION_INIT, 1));
            if (!strcasecmp(value, "db_txn_nosync"))
                  return (__dbenv_set_flags(dbenv, DB_TXN_NOSYNC, 1));
            if (!strcasecmp(value, "db_txn_write_nosync"))
                  return (
                      __dbenv_set_flags(dbenv, DB_TXN_WRITE_NOSYNC, 1));
            if (!strcasecmp(value, "db_yieldcpu"))
                  return (__dbenv_set_flags(dbenv, DB_YIELDCPU, 1));
            goto badarg;
      }

      if (!strcasecmp(name, "set_lg_bsize")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__log_set_lg_bsize(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lg_max")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__log_set_lg_max(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lg_regionmax")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__log_set_lg_regionmax(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lg_dir") ||
          !strcasecmp(name, "db_log_dir"))            /* Compatibility. */
            return (__log_set_lg_dir(dbenv, value));

      if (!strcasecmp(name, "set_lk_detect")) {
            if (sscanf(value, "%40s %c", arg, &v4) != 1)
                  goto badarg;
            if (!strcasecmp(value, "db_lock_default"))
                  flags = DB_LOCK_DEFAULT;
            else if (!strcasecmp(value, "db_lock_expire"))
                  flags = DB_LOCK_EXPIRE;
            else if (!strcasecmp(value, "db_lock_maxlocks"))
                  flags = DB_LOCK_MAXLOCKS;
            else if (!strcasecmp(value, "db_lock_maxwrite"))
                  flags = DB_LOCK_MAXWRITE;
            else if (!strcasecmp(value, "db_lock_minlocks"))
                  flags = DB_LOCK_MINLOCKS;
            else if (!strcasecmp(value, "db_lock_minwrite"))
                  flags = DB_LOCK_MINWRITE;
            else if (!strcasecmp(value, "db_lock_oldest"))
                  flags = DB_LOCK_OLDEST;
            else if (!strcasecmp(value, "db_lock_random"))
                  flags = DB_LOCK_RANDOM;
            else if (!strcasecmp(value, "db_lock_youngest"))
                  flags = DB_LOCK_YOUNGEST;
            else
                  goto badarg;
            return (__lock_set_lk_detect(dbenv, flags));
      }

      if (!strcasecmp(name, "set_lk_max")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__lock_set_lk_max(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lk_max_locks")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__lock_set_lk_max_locks(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lk_max_lockers")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__lock_set_lk_max_lockers(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lk_max_objects")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__lock_set_lk_max_objects(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_lock_timeout")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__lock_set_env_timeout(
                dbenv, (u_int32_t)v1, DB_SET_LOCK_TIMEOUT));
      }

      if (!strcasecmp(name, "set_mp_max_openfd")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, INT_MAX);
            return (__memp_set_mp_max_openfd(dbenv, (int)v1));
      }

      if (!strcasecmp(name, "set_mp_max_write")) {
            if (sscanf(value, "%lu %lu %c", &v1, &v2, &v4) != 2)
                  goto badarg;
            __DB_OVFL(v1, INT_MAX);
            __DB_OVFL(v2, INT_MAX);
            return (__memp_set_mp_max_write(dbenv, (int)v1, (int)v2));
      }

      if (!strcasecmp(name, "set_mp_mmapsize")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__memp_set_mp_mmapsize(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_region_init")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1 || v1 != 1)
                  goto badarg;
            return (__dbenv_set_flags(
                dbenv, DB_REGION_INIT, v1 == 0 ? 0 : 1));
      }

      if (!strcasecmp(name, "set_shm_key")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            return (__dbenv_set_shm_key(dbenv, (long)v1));
      }

      if (!strcasecmp(name, "set_tas_spins")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__dbenv_set_tas_spins(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_tmp_dir") ||
          !strcasecmp(name, "db_tmp_dir"))            /* Compatibility.*/
            return (__dbenv_set_tmp_dir(dbenv, value));

      if (!strcasecmp(name, "set_tx_max")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__txn_set_tx_max(dbenv, (u_int32_t)v1));
      }

      if (!strcasecmp(name, "set_txn_timeout")) {
            if (sscanf(value, "%lu %c", &v1, &v4) != 1)
                  goto badarg;
            __DB_OVFL(v1, UINT32_MAX);
            return (__lock_set_env_timeout(
                dbenv, (u_int32_t)v1, DB_SET_TXN_TIMEOUT));
      }

      if (!strcasecmp(name, "set_verbose")) {
            if (sscanf(value, "%40s %c", arg, &v4) != 1)
                  goto badarg;

            else if (!strcasecmp(value, "db_verb_deadlock"))
                  flags = DB_VERB_DEADLOCK;
            else if (!strcasecmp(value, "db_verb_recovery"))
                  flags = DB_VERB_RECOVERY;
            else if (!strcasecmp(value, "db_verb_replication"))
                  flags = DB_VERB_REPLICATION;
            else if (!strcasecmp(value, "db_verb_waitsfor"))
                  flags = DB_VERB_WAITSFOR;
            else
                  goto badarg;
            return (__dbenv_set_verbose(dbenv, flags, 1));
      }

      __db_err(dbenv, "unrecognized name-value pair: %s", s);
      return (EINVAL);

badarg:     __db_err(dbenv, "incorrect arguments for name-value pair: %s", s);
      return (EINVAL);

toobig:     __db_err(dbenv,
          "%s: %lu larger than maximum value %lu", s, __v, __max);
      return (EINVAL);
}

/*
 * __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;
{
      u_int32_t id;
      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(path, &isdir)) != 0) {
            __db_err(dbenv, "%s: %s", path, db_strerror(ret));
            return (ret);
      }
      if (!isdir) {
            __db_err(dbenv, "%s: %s", path, db_strerror(EINVAL));
            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). */
      for (trv = path + strlen(path), __os_id(&id); *--trv == 'X'; id /= 10)
            *trv = '0' + (id % 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("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,
                      "tmp_open: %s: %s", path, db_strerror(ret));
                  return (ret);
            }

            /*
             * Generate temporary file names in a backwards-compatible way.
             * If id == 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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