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Sourcecode: db4.1 version File versions

log.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2002
 *    Sleepycat Software.  All rights reserved.
 */
#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: log.c,v 11.111 2002/08/16 00:27:44 ubell Exp $";
#endif /* not lint */

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

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

#include "db_int.h"
#include "dbinc/crypto.h"
#include "dbinc/hmac.h"
#include "dbinc/log.h"
#include "dbinc/txn.h"

static int __log_init __P((DB_ENV *, DB_LOG *));
static int __log_recover __P((DB_LOG *));
static size_t __log_region_size __P((DB_ENV *));
static int __log_zero __P((DB_ENV *, DB_LSN *, DB_LSN *));

/*
 * __log_open --
 *    Internal version of log_open: only called from DB_ENV->open.
 *
 * PUBLIC: int __log_open __P((DB_ENV *));
 */
int
__log_open(dbenv)
      DB_ENV *dbenv;
{
      DB_LOG *dblp;
      LOG *lp;
      int ret;

      /* Create/initialize the DB_LOG structure. */
      if ((ret = __os_calloc(dbenv, 1, sizeof(DB_LOG), &dblp)) != 0)
            return (ret);
      dblp->dbenv = dbenv;

      /* Join/create the log region. */
      dblp->reginfo.type = REGION_TYPE_LOG;
      dblp->reginfo.id = INVALID_REGION_ID;
      dblp->reginfo.mode = dbenv->db_mode;
      dblp->reginfo.flags = REGION_JOIN_OK;
      if (F_ISSET(dbenv, DB_ENV_CREATE))
            F_SET(&dblp->reginfo, REGION_CREATE_OK);
      if ((ret = __db_r_attach(
          dbenv, &dblp->reginfo, __log_region_size(dbenv))) != 0)
            goto err;

      /* If we created the region, initialize it. */
      if (F_ISSET(&dblp->reginfo, REGION_CREATE))
            if ((ret = __log_init(dbenv, dblp)) != 0)
                  goto err;

      /* Set the local addresses. */
      lp = dblp->reginfo.primary =
          R_ADDR(&dblp->reginfo, dblp->reginfo.rp->primary);

      /*
       * If the region is threaded, then we have to lock both the handles
       * and the region, and we need to allocate a mutex for that purpose.
       */
      if (F_ISSET(dbenv, DB_ENV_THREAD) &&
          (ret = __db_mutex_setup(dbenv, &dblp->reginfo, &dblp->mutexp,
          MUTEX_ALLOC | MUTEX_NO_RLOCK)) != 0)
            goto err;

      /* Initialize the rest of the structure. */
      dblp->bufp = R_ADDR(&dblp->reginfo, lp->buffer_off);

      /*
       * Set the handle -- we may be about to run recovery, which allocates
       * log cursors.  Log cursors require logging be already configured,
       * and the handle being set is what demonstrates that.
       *
       * If we created the region, run recovery.  If that fails, make sure
       * we reset the log handle before cleaning up, otherwise we will try
       * and clean up again in the mainline DB_ENV initialization code.
       */
      dbenv->lg_handle = dblp;

      if (F_ISSET(&dblp->reginfo, REGION_CREATE)) {
            if ((ret = __log_recover(dblp)) != 0) {
                  dbenv->lg_handle = NULL;
                  goto err;
            }

            /*
             * We first take the log file size from the environment, if
             * specified.  If that wasn't set, recovery may have set it
             * from the persistent information in a log file header.  If
             * that didn't set it either, we default.
             */
            if (lp->log_size == 0)
                  lp->log_size = lp->log_nsize = LG_MAX_DEFAULT;
      } else {
            /*
             * A process joining the region may have reset the log file
             * size, too.  If so, it only affects the next log file we
             * create.
             */
             if (dbenv->lg_size != 0)
                  lp->log_nsize = dbenv->lg_size;
      }

      R_UNLOCK(dbenv, &dblp->reginfo);
      return (0);

err:  if (dblp->reginfo.addr != NULL) {
            if (F_ISSET(&dblp->reginfo, REGION_CREATE))
                  ret = __db_panic(dbenv, ret);
            R_UNLOCK(dbenv, &dblp->reginfo);
            (void)__db_r_detach(dbenv, &dblp->reginfo, 0);
      }

      if (dblp->mutexp != NULL)
            __db_mutex_free(dbenv, &dblp->reginfo, dblp->mutexp);

      __os_free(dbenv, dblp);

      return (ret);
}

/*
 * __log_init --
 *    Initialize a log region in shared memory.
 */
static int
__log_init(dbenv, dblp)
      DB_ENV *dbenv;
      DB_LOG *dblp;
{
      DB_MUTEX *flush_mutexp;
      LOG *region;
      int ret;
      void *p;
#ifdef  HAVE_MUTEX_SYSTEM_RESOURCES
      u_int8_t *addr;
#endif

      if ((ret = __db_shalloc(dblp->reginfo.addr,
          sizeof(*region), 0, &dblp->reginfo.primary)) != 0)
            goto mem_err;
      dblp->reginfo.rp->primary =
          R_OFFSET(&dblp->reginfo, dblp->reginfo.primary);
      region = dblp->reginfo.primary;
      memset(region, 0, sizeof(*region));

      region->fid_max = 0;
      SH_TAILQ_INIT(&region->fq);
      region->free_fid_stack = INVALID_ROFF;
      region->free_fids = region->free_fids_alloced = 0;

      /* Initialize LOG LSNs. */
      INIT_LSN(region->lsn);
      INIT_LSN(region->ready_lsn);
      INIT_LSN(region->t_lsn);

      /*
       * It's possible to be waiting for an LSN of [1][0], if a replication
       * client gets the first log record out of order.  An LSN of [0][0]
       * signifies that we're not waiting.
       */
      ZERO_LSN(region->waiting_lsn);

      /*
       * Log makes note of the fact that it ran into a checkpoint on
       * startup if it did so, as a recovery optimization.  A zero
       * LSN signifies that it hasn't found one [yet].
       */
      ZERO_LSN(region->cached_ckp_lsn);

#ifdef  HAVE_MUTEX_SYSTEM_RESOURCES
      /* Allocate room for the log maintenance info and initialize it. */
      if ((ret = __db_shalloc(dblp->reginfo.addr,
          sizeof(REGMAINT) + LG_MAINT_SIZE, 0, &addr)) != 0)
            goto mem_err;
      __db_maintinit(&dblp->reginfo, addr, LG_MAINT_SIZE);
      region->maint_off = R_OFFSET(&dblp->reginfo, addr);
#endif

      if ((ret = __db_mutex_setup(dbenv, &dblp->reginfo, &region->fq_mutex,
          MUTEX_NO_RLOCK)) != 0)
            return (ret);

      /*
       * We must create a place for the flush mutex separately; mutexes have
       * to be aligned to MUTEX_ALIGN, and the only way to guarantee that is
       * to make sure they're at the beginning of a shalloc'ed chunk.
       */
      if ((ret = __db_shalloc(dblp->reginfo.addr,
          sizeof(DB_MUTEX), MUTEX_ALIGN, &flush_mutexp)) != 0)
            goto mem_err;
      if ((ret = __db_mutex_setup(dbenv, &dblp->reginfo, flush_mutexp,
          MUTEX_NO_RLOCK)) != 0)
            return (ret);
      region->flush_mutex_off = R_OFFSET(&dblp->reginfo, flush_mutexp);

      /* Initialize the buffer. */
      if ((ret =
          __db_shalloc(dblp->reginfo.addr, dbenv->lg_bsize, 0, &p)) != 0) {
mem_err:    __db_err(dbenv, "Unable to allocate memory for the log buffer");
            return (ret);
      }
      region->buffer_size = dbenv->lg_bsize;
      region->buffer_off = R_OFFSET(&dblp->reginfo, p);
      region->log_size = region->log_nsize = dbenv->lg_size;

      /* Initialize the commit Queue. */
      SH_TAILQ_INIT(&region->free_commits);
      SH_TAILQ_INIT(&region->commits);
      region->ncommit = 0;

      /*
       * Fill in the log's persistent header.  Don't fill in the log file
       * sizes, as they may change at any time and so have to be filled in
       * as each log file is created.
       */
      region->persist.magic = DB_LOGMAGIC;
      region->persist.version = DB_LOGVERSION;
      region->persist.mode = (u_int32_t)dbenv->db_mode;

      return (0);
}

/*
 * __log_recover --
 *    Recover a log.
 */
static int
__log_recover(dblp)
      DB_LOG *dblp;
{
      DBT dbt;
      DB_ENV *dbenv;
      DB_LOGC *logc;
      DB_LSN lsn;
      LOG *lp;
      u_int32_t cnt, rectype;
      int ret;
      logfile_validity status;

      logc = NULL;
      dbenv = dblp->dbenv;
      lp = dblp->reginfo.primary;

      /*
       * Find a log file.  If none exist, we simply return, leaving
       * everything initialized to a new log.
       */
      if ((ret = __log_find(dblp, 0, &cnt, &status)) != 0)
            return (ret);
      if (cnt == 0)
            return (0);

      /*
       * If the last file is an old version, readable or no, start a new
       * file.  Don't bother finding the end of the last log file;
       * we assume that it's valid in its entirety, since the user
       * should have shut down cleanly or run recovery before upgrading.
       */
      if (status == DB_LV_OLD_READABLE || status == DB_LV_OLD_UNREADABLE) {
            lp->lsn.file = lp->s_lsn.file = cnt + 1;
            lp->lsn.offset = lp->s_lsn.offset = 0;
            goto skipsearch;
      }
      DB_ASSERT(status == DB_LV_NORMAL);

      /*
       * We have the last useful log file and we've loaded any persistent
       * information.  Set the end point of the log past the end of the last
       * file. Read the last file, looking for the last checkpoint and
       * the log's end.
       */
      lp->lsn.file = cnt + 1;
      lp->lsn.offset = 0;
      lsn.file = cnt;
      lsn.offset = 0;

      /*
       * Allocate a cursor and set it to the first record.  This shouldn't
       * fail, leave error messages on.
       */
      if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
            return (ret);
      F_SET(logc, DB_LOG_LOCKED);
      memset(&dbt, 0, sizeof(dbt));
      if ((ret = logc->get(logc, &lsn, &dbt, DB_SET)) != 0)
            goto err;

      /*
       * Read to the end of the file.  This may fail at some point, so
       * turn off error messages.
       */
      F_SET(logc, DB_LOG_SILENT_ERR);
      while (logc->get(logc, &lsn, &dbt, DB_NEXT) == 0) {
            if (dbt.size < sizeof(u_int32_t))
                  continue;
            memcpy(&rectype, dbt.data, sizeof(u_int32_t));
            if (rectype == DB___txn_ckp)
                  /*
                   * If we happen to run into a checkpoint, cache its
                   * LSN so that the transaction system doesn't have
                   * to walk this log file again looking for it.
                   */
                  lp->cached_ckp_lsn = lsn;
      }
      F_CLR(logc, DB_LOG_SILENT_ERR);

      /*
       * We now know where the end of the log is.  Set the first LSN that
       * we want to return to an application and the LSN of the last known
       * record on disk.
       */
      lp->lsn = lsn;
      lp->s_lsn = lsn;
      lp->lsn.offset += logc->c_len;
      lp->s_lsn.offset += logc->c_len;

      /* Set up the current buffer information, too. */
      lp->len = logc->c_len;
      lp->b_off = 0;
      lp->w_off = lp->lsn.offset;

skipsearch:
      if (FLD_ISSET(dbenv->verbose, DB_VERB_RECOVERY))
            __db_err(dbenv,
                "Finding last valid log LSN: file: %lu offset %lu",
                (u_long)lp->lsn.file, (u_long)lp->lsn.offset);

err:  if (logc != NULL)
            (void)logc->close(logc, 0);

      return (ret);
}

/*
 * __log_find --
 *    Try to find a log file.  If find_first is set, valp will contain
 * the number of the first readable log file, else it will contain the number
 * of the last log file (which may be too old to read).
 *
 * PUBLIC: int __log_find __P((DB_LOG *, int, u_int32_t *, logfile_validity *));
 */
int
__log_find(dblp, find_first, valp, statusp)
      DB_LOG *dblp;
      int find_first;
      u_int32_t *valp;
      logfile_validity *statusp;
{
      DB_ENV *dbenv;
      logfile_validity logval_status, status;
      u_int32_t clv, logval;
      int cnt, fcnt, ret;
      const char *dir;
      char *c, **names, *p, *q, savech;

      dbenv = dblp->dbenv;
      logval_status = status = DB_LV_NONEXISTENT;

      /* Return a value of 0 as the log file number on failure. */
      *valp = 0;

      /* Find the directory name. */
      if ((ret = __log_name(dblp, 1, &p, NULL, 0)) != 0)
            return (ret);
      if ((q = __db_rpath(p)) == NULL) {
            COMPQUIET(savech, 0);
            dir = PATH_DOT;
      } else {
            savech = *q;
            *q = '\0';
            dir = p;
      }

      /* Get the list of file names. */
      ret = __os_dirlist(dbenv, dir, &names, &fcnt);

      /*
       * !!!
       * We overwrote a byte in the string with a nul.  Restore the string
       * so that the diagnostic checks in the memory allocation code work
       * and any error messages display the right file name.
       */
      if (q != NULL)
            *q = savech;

      if (ret != 0) {
            __db_err(dbenv, "%s: %s", dir, db_strerror(ret));
            __os_free(dbenv, p);
            return (ret);
      }

      /* Search for a valid log file name. */
      for (cnt = fcnt, clv = logval = 0; --cnt >= 0;) {
            if (strncmp(names[cnt], LFPREFIX, sizeof(LFPREFIX) - 1) != 0)
                  continue;

            /*
             * Names of the form log\.[0-9]* are reserved for DB.  Other
             * names sharing LFPREFIX, such as "log.db", are legal.
             */
            for (c = names[cnt] + sizeof(LFPREFIX) - 1; *c != '\0'; c++)
                  if (!isdigit((int)*c))
                        break;
            if (*c != '\0')
                  continue;

            /*
             * Use atol, not atoi; if an "int" is 16-bits, the largest
             * log file name won't fit.
             */
            clv = atol(names[cnt] + (sizeof(LFPREFIX) - 1));

            /*
             * If searching for the first log file, we want to return the
             * oldest log file we can read, or, if no readable log files
             * exist, the newest log file we can't read (the crossover
             * point between the old and new versions of the log file).
             *
             * If we're searching for the last log file, we want to return
             * the newest log file, period.
             *
             * Readable log files should never preceede unreadable log
             * files, that would mean the admin seriously screwed up.
             */
            if (find_first) {
                  if (logval != 0 &&
                      status != DB_LV_OLD_UNREADABLE && clv > logval)
                        continue;
            } else
                  if (logval != 0 && clv < logval)
                        continue;

            if ((ret = __log_valid(dblp, clv, 1, &status)) != 0) {
                  __db_err(dbenv, "Invalid log file: %s: %s",
                      names[cnt], db_strerror(ret));
                  goto err;
            }
            switch (status) {
            case DB_LV_NONEXISTENT:
                  /* __log_valid never returns DB_LV_NONEXISTENT. */
                  DB_ASSERT(0);
                  break;
            case DB_LV_INCOMPLETE:
                  /*
                   * The last log file may not have been initialized --
                   * it's possible to create a log file but not write
                   * anything to it.  If performing recovery (that is,
                   * if find_first isn't set), ignore the file, it's
                   * not interesting.  If we're searching for the first
                   * log record, return the file (assuming we don't find
                   * something better), as the "real" first log record
                   * is likely to be in the log buffer, and we want to
                   * set the file LSN for our return.
                   */
                  if (find_first)
                        goto found;
                  break;
            case DB_LV_OLD_UNREADABLE:
                  /*
                   * If we're searching for the first log file, then we
                   * only want this file if we don't yet have a file or
                   * already have an unreadable file and this one is
                   * newer than that one.  If we're searching for the
                   * last log file, we always want this file because we
                   * wouldn't be here if it wasn't newer than our current
                   * choice.
                   */
                  if (!find_first || logval == 0 ||
                      (status == DB_LV_OLD_UNREADABLE && clv > logval))
                        goto found;
                  break;
            case DB_LV_NORMAL:
            case DB_LV_OLD_READABLE:
found:                  logval = clv;
                  logval_status = status;
                  break;
            }
      }

      *valp = logval;

err:  __os_dirfree(dbenv, names, fcnt);
      __os_free(dbenv, p);
      *statusp = logval_status;

      return (ret);
}

/*
 * log_valid --
 *    Validate a log file.  Returns an error code in the event of
 *    a fatal flaw in a the specified log file;  returns success with
 *    a code indicating the currentness and completeness of the specified
 *    log file if it is not unexpectedly flawed (that is, if it's perfectly
 *    normal, if it's zero-length, or if it's an old version).
 *
 * PUBLIC: int __log_valid __P((DB_LOG *, u_int32_t, int, logfile_validity *));
 */
int
__log_valid(dblp, number, set_persist, statusp)
      DB_LOG *dblp;
      u_int32_t number;
      int set_persist;
      logfile_validity *statusp;
{
      DB_CIPHER *db_cipher;
      DB_ENV *dbenv;
      DB_FH fh;
      HDR *hdr;
      LOG *region;
      LOGP *persist;
      logfile_validity status;
      size_t hdrsize, nw, recsize;
      int is_hmac, need_free, ret;
      u_int8_t *tmp;
      char *fname;

      dbenv = dblp->dbenv;
      db_cipher = dbenv->crypto_handle;
      persist = NULL;
      status = DB_LV_NORMAL;

      /* Try to open the log file. */
      if ((ret = __log_name(dblp,
          number, &fname, &fh, DB_OSO_RDONLY | DB_OSO_SEQ)) != 0) {
            __os_free(dbenv, fname);
            return (ret);
      }

      need_free = 0;
      hdrsize = HDR_NORMAL_SZ;
      is_hmac = 0;
      recsize = sizeof(LOGP);
      if (CRYPTO_ON(dbenv)) {
            hdrsize = HDR_CRYPTO_SZ;
            recsize = sizeof(LOGP);
            recsize += db_cipher->adj_size(recsize);
            is_hmac = 1;
      }
      if ((ret = __os_calloc(dbenv, 1, recsize + hdrsize, &tmp)) != 0)
            return (ret);
      need_free = 1;
      hdr = (HDR *)tmp;
      persist = (LOGP *)(tmp + hdrsize);
      /* Try to read the header. */
      if ((ret = __os_read(dbenv, &fh, tmp, recsize + hdrsize, &nw)) != 0 ||
          nw != recsize + hdrsize) {
            if (ret == 0)
                  status = DB_LV_INCOMPLETE;
            else
                  /*
                   * The error was a fatal read error, not just an
                   * incompletely initialized log file.
                   */
                  __db_err(dbenv, "Ignoring log file: %s: %s",
                      fname, db_strerror(ret));

            (void)__os_closehandle(dbenv, &fh);
            goto err;
      }
      (void)__os_closehandle(dbenv, &fh);

      /*
       * Now we have to validate the persistent record.  We have
       * several scenarios we have to deal with:
       *
       * 1.  User has crypto turned on:
       *    - They're reading an old, unencrypted log file
       *      .  We will fail the record size match check below.
       *    - They're reading a current, unencrypted log file
       *      .  We will fail the record size match check below.
       *    - They're reading an old, encrypted log file [NOT YET]
       *      .  After decryption we'll fail the version check.  [NOT YET]
       *    - They're reading a current, encrypted log file
       *      .  We should proceed as usual.
       * 2.  User has crypto turned off:
       *    - They're reading an old, unencrypted log file
       *      .  We will fail the version check.
       *    - They're reading a current, unencrypted log file
       *      .  We should proceed as usual.
       *    - They're reading an old, encrypted log file [NOT YET]
       *      .  We'll fail the magic number check (it is encrypted).
       *    - They're reading a current, encrypted log file
       *      .  We'll fail the magic number check (it is encrypted).
       */
      if (CRYPTO_ON(dbenv)) {
            /*
             * If we are trying to decrypt an unencrypted log
             * we can only detect that by having an unreasonable
             * data length for our persistent data.
             */
            if ((hdr->len - hdrsize) != sizeof(LOGP)) {
                  __db_err(dbenv, "log record size mismatch");
                  goto err;
            }
            /* Check the checksum and decrypt. */
            if ((ret = __db_check_chksum(dbenv, db_cipher, &hdr->chksum[0],
                (u_int8_t *)persist, hdr->len - hdrsize, is_hmac)) != 0) {
                  __db_err(dbenv, "log record checksum mismatch");
                  goto err;
            }
            if ((ret = db_cipher->decrypt(dbenv, db_cipher->data,
                &hdr->iv[0], (u_int8_t *)persist, hdr->len - hdrsize)) != 0)
                  goto err;
      }

      /* Validate the header. */
      if (persist->magic != DB_LOGMAGIC) {
            __db_err(dbenv,
                "Ignoring log file: %s: magic number %lx, not %lx",
                fname, (u_long)persist->magic, (u_long)DB_LOGMAGIC);
            ret = EINVAL;
            goto err;
      }

      /*
       * Set our status code to indicate whether the log file
       * belongs to an unreadable or readable old version;  leave it
       * alone if and only if the log file version is the current one.
       */
      if (persist->version > DB_LOGVERSION) {
            /* This is a fatal error--the log file is newer than DB. */
            __db_err(dbenv,
                "Ignoring log file: %s: unsupported log version %lu",
                fname, (u_long)persist->version);
            ret = EINVAL;
            goto err;
      } else if (persist->version < DB_LOGOLDVER) {
            status = DB_LV_OLD_UNREADABLE;
            /*
             * We don't want to set persistent info based on an
             * unreadable region, so jump to "err".
             */
            goto err;
      } else if (persist->version < DB_LOGVERSION)
            status = DB_LV_OLD_READABLE;

      /*
       * Only if we have a current log do we verify the checksum.
       * We could not check the checksum before checking the magic
       * and version because old log hdrs have the length and checksum
       * in a different location.
       */
      if (!CRYPTO_ON(dbenv) && ((ret = __db_check_chksum(dbenv,
          db_cipher, &hdr->chksum[0], (u_int8_t *)persist,
          hdr->len - hdrsize, is_hmac)) != 0)) {
            __db_err(dbenv, "log record checksum mismatch");
            goto err;
      }

      /*
       * If the log is readable so far and we're doing system initialization,
       * set the region's persistent information based on the headers.
       *
       * Always set the current log file size.  Only set the next log file's
       * size if the application hasn't set it already.
       *
       * XXX
       * Always use the persistent header's mode, regardless of what was set
       * in the current environment.  We've always done it this way, but it's
       * probably a bug -- I can't think of a way not-changing the mode would
       * be a problem, though.
       */
      if (set_persist) {
            region = dblp->reginfo.primary;
            region->log_size = persist->log_size;
            if (region->log_nsize == 0)
                  region->log_nsize = persist->log_size;
            region->persist.mode = persist->mode;
      }

err:  __os_free(dbenv, fname);
      if (need_free)
            __os_free(dbenv, tmp);
      *statusp = status;
      return (ret);
}

/*
 * __log_dbenv_refresh --
 *    Clean up after the log system on a close or failed open.  Called only
 * from __dbenv_refresh.  (Formerly called __log_close.)
 *
 * PUBLIC: int __log_dbenv_refresh __P((DB_ENV *));
 */
int
__log_dbenv_refresh(dbenv)
      DB_ENV *dbenv;
{
      DB_LOG *dblp;
      int ret, t_ret;

      dblp = dbenv->lg_handle;

      /* We may have opened files as part of XA; if so, close them. */
      F_SET(dblp, DBLOG_RECOVER);
      ret = __dbreg_close_files(dbenv);

      /* Discard the per-thread lock. */
      if (dblp->mutexp != NULL)
            __db_mutex_free(dbenv, &dblp->reginfo, dblp->mutexp);

      /* Detach from the region. */
      if ((t_ret =
          __db_r_detach(dbenv, &dblp->reginfo, 0)) != 0 && ret == 0)
            ret = t_ret;

      /* Close open files, release allocated memory. */
      if (F_ISSET(&dblp->lfh, DB_FH_VALID) &&
          (t_ret = __os_closehandle(dbenv, &dblp->lfh)) != 0 && ret == 0)
            ret = t_ret;
      if (dblp->dbentry != NULL)
            __os_free(dbenv, dblp->dbentry);

      __os_free(dbenv, dblp);

      dbenv->lg_handle = NULL;
      return (ret);
}

/*
 * __log_stat --
 *    Return log statistics.
 *
 * PUBLIC: int __log_stat __P((DB_ENV *, DB_LOG_STAT **, u_int32_t));
 */
int
__log_stat(dbenv, statp, flags)
      DB_ENV *dbenv;
      DB_LOG_STAT **statp;
      u_int32_t flags;
{
      DB_LOG *dblp;
      DB_LOG_STAT *stats;
      LOG *region;
      int ret;

      PANIC_CHECK(dbenv);
      ENV_REQUIRES_CONFIG(dbenv,
          dbenv->lg_handle, "DB_ENV->log_stat", DB_INIT_LOG);

      *statp = NULL;
      if ((ret = __db_fchk(dbenv,
          "DB_ENV->log_stat", flags, DB_STAT_CLEAR)) != 0)
            return (ret);

      dblp = dbenv->lg_handle;
      region = dblp->reginfo.primary;

      if ((ret = __os_umalloc(dbenv, sizeof(DB_LOG_STAT), &stats)) != 0)
            return (ret);

      /* Copy out the global statistics. */
      R_LOCK(dbenv, &dblp->reginfo);
      *stats = region->stat;
      if (LF_ISSET(DB_STAT_CLEAR))
            memset(&region->stat, 0, sizeof(region->stat));

      stats->st_magic = region->persist.magic;
      stats->st_version = region->persist.version;
      stats->st_mode = region->persist.mode;
      stats->st_lg_bsize = region->buffer_size;
      stats->st_lg_size = region->log_nsize;

      stats->st_region_wait = dblp->reginfo.rp->mutex.mutex_set_wait;
      stats->st_region_nowait = dblp->reginfo.rp->mutex.mutex_set_nowait;
      if (LF_ISSET(DB_STAT_CLEAR)) {
            dblp->reginfo.rp->mutex.mutex_set_wait = 0;
            dblp->reginfo.rp->mutex.mutex_set_nowait = 0;
      }
      stats->st_regsize = dblp->reginfo.rp->size;

      stats->st_cur_file = region->lsn.file;
      stats->st_cur_offset = region->lsn.offset;
      stats->st_disk_file = region->s_lsn.file;
      stats->st_disk_offset = region->s_lsn.offset;

      R_UNLOCK(dbenv, &dblp->reginfo);

      *statp = stats;
      return (0);
}

/*
 * __log_get_cached_ckp_lsn --
 *    Retrieve any last checkpoint LSN that we may have found on startup.
 *
 * PUBLIC: void __log_get_cached_ckp_lsn __P((DB_ENV *, DB_LSN *));
 */
void
__log_get_cached_ckp_lsn(dbenv, ckp_lsnp)
      DB_ENV *dbenv;
      DB_LSN *ckp_lsnp;
{
      DB_LOG *dblp;
      LOG *lp;

      dblp = (DB_LOG *)dbenv->lg_handle;
      lp = (LOG *)dblp->reginfo.primary;

      R_LOCK(dbenv, &dblp->reginfo);
      *ckp_lsnp = lp->cached_ckp_lsn;
      R_UNLOCK(dbenv, &dblp->reginfo);
}

/*
 * __log_region_size --
 *    Return the amount of space needed for the log region.
 *    Make the region large enough to hold txn_max transaction
 *    detail structures  plus some space to hold thread handles
 *    and the beginning of the shalloc region and anything we
 *    need for mutex system resource recording.
 */
static size_t
__log_region_size(dbenv)
      DB_ENV *dbenv;
{
      size_t s;

      s = dbenv->lg_regionmax + dbenv->lg_bsize;
#ifdef HAVE_MUTEX_SYSTEM_RESOURCES
      if (F_ISSET(dbenv, DB_ENV_THREAD))
            s += sizeof(REGMAINT) + LG_MAINT_SIZE;
#endif
      return (s);
}

/*
 * __log_region_destroy
 *    Destroy any region maintenance info.
 *
 * PUBLIC: void __log_region_destroy __P((DB_ENV *, REGINFO *));
 */
void
__log_region_destroy(dbenv, infop)
      DB_ENV *dbenv;
      REGINFO *infop;
{
      __db_shlocks_destroy(infop, (REGMAINT *)R_ADDR(infop,
          ((LOG *)R_ADDR(infop, infop->rp->primary))->maint_off));

      COMPQUIET(dbenv, NULL);
      COMPQUIET(infop, NULL);
}

/*
 * __log_vtruncate
 *    This is a virtual truncate.  We set up the log indicators to
 * make everyone believe that the given record is the last one in the
 * log.  Returns with the next valid LSN (i.e., the LSN of the next
 * record to be written). This is used in replication to discard records
 * in the log file that do not agree with the master.
 *
 * PUBLIC: int __log_vtruncate __P((DB_ENV *, DB_LSN *, DB_LSN *));
 */
int
__log_vtruncate(dbenv, lsn, ckplsn)
      DB_ENV *dbenv;
      DB_LSN *lsn, *ckplsn;
{
      DBT log_dbt;
      DB_FH fh;
      DB_LOG *dblp;
      DB_LOGC *logc;
      DB_LSN end_lsn;
      LOG *lp;
      u_int32_t bytes, c_len;
      int fn, ret, t_ret;
      char *fname;

      /* Need to find out the length of this soon-to-be-last record. */
      if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
            return (ret);
      memset(&log_dbt, 0, sizeof(log_dbt));
      ret = logc->get(logc, lsn, &log_dbt, DB_SET);
      c_len = logc->c_len;
      if ((t_ret = logc->close(logc, 0)) != 0 && ret == 0)
            ret = t_ret;
      if (ret != 0)
            return (ret);

      /* Now do the truncate. */
      dblp = (DB_LOG *)dbenv->lg_handle;
      lp = (LOG *)dblp->reginfo.primary;

      R_LOCK(dbenv, &dblp->reginfo);
      end_lsn = lp->lsn;
      lp->lsn = *lsn;
      lp->len = c_len;
      lp->lsn.offset += lp->len;

      /*
       * I am going to assume that the number of bytes written since
       * the last checkpoint doesn't exceed a 32-bit number.
       */
      DB_ASSERT(lp->lsn.file >= ckplsn->file);
      bytes = 0;
      if (ckplsn->file != lp->lsn.file) {
            bytes = lp->log_size - ckplsn->offset;
            if (lp->lsn.file > ckplsn->file + 1)
                  bytes += lp->log_size *
                      (lp->lsn.file - ckplsn->file - 1);
            bytes += lp->lsn.offset;
      } else
            bytes = lp->lsn.offset - ckplsn->offset;

      lp->stat.st_wc_mbytes += bytes / MEGABYTE;
      lp->stat.st_wc_bytes += bytes % MEGABYTE;

      /*
       * If the saved lsn is greater than our new end of log, reset it
       * to our current end of log.
       */
      if (log_compare(&lp->s_lsn, lsn) > 0)
            lp->s_lsn = lp->lsn;

      /*
       * If the new end of log is in the middle of the buffer,
       * don't change the w_off or f_lsn.  If the new end is
       * before the w_off then reset w_off and f_lsn to the new
       * end of log.
       */
      if (lp->w_off >= lp->lsn.offset) {
            lp->f_lsn = lp->lsn;
            lp->w_off = lp->lsn.offset;
            lp->b_off = 0;
      } else
            lp->b_off = lp->lsn.offset - lp->w_off;

      ZERO_LSN(lp->waiting_lsn);
      lp->ready_lsn = lp->lsn;
      lp->wait_recs = 0;
      lp->rcvd_recs = 0;

      /* Now throw away any extra log files that we have around. */
      for (fn = lp->lsn.file + 1;; fn++) {
            if (__log_name(dblp, fn, &fname, &fh, DB_OSO_RDONLY) != 0) {
                  __os_free(dbenv, fname);
                  break;
            }
            (void)__os_closehandle(dbenv, &fh);
            ret = __os_unlink(dbenv, fname);
            __os_free(dbenv, fname);
            if (ret != 0)
                  goto err;
      }

      /* Truncate the log to the new point. */
      if ((ret = __log_zero(dbenv, &lp->lsn, &end_lsn)) != 0)
            goto err;

err:  R_UNLOCK(dbenv, &dblp->reginfo);
      return (ret);
}

/*
 * __log_is_outdated --
 *    Used by the replication system to identify if a client's logs
 * are too old.  The log represented by dbenv is compared to the file
 * number passed in fnum.  If the log file fnum does not exist and is
 * lower-numbered than the current logs, the we return *outdatedp non
 * zero, else we return it 0.
 *
 * PUBLIC: int __log_is_outdated __P((DB_ENV *dbenv,
 * PUBLIC:     u_int32_t fnum, int *outdatedp));
 */
int
__log_is_outdated(dbenv, fnum, outdatedp)
      DB_ENV *dbenv;
      u_int32_t fnum;
      int *outdatedp;
{
      DB_LOG *dblp;
      LOG *lp;
      char *name;
      int ret;
      u_int32_t cfile;

      dblp = dbenv->lg_handle;
      *outdatedp = 0;

      if ((ret = __log_name(dblp, fnum, &name, NULL, 0)) != 0)
            return (ret);

      /* If the file exists, we're just fine. */
      if (__os_exists(name, NULL) == 0)
            goto out;

      /*
       * It didn't exist, decide if the file number is too big or
       * too little.  If it's too little, then we need to indicate
       * that the LSN is outdated.
       */
      R_LOCK(dbenv, &dblp->reginfo);
      lp = (LOG *)dblp->reginfo.primary;
      cfile = lp->lsn.file;
      R_UNLOCK(dbenv, &dblp->reginfo);

      if (cfile > fnum)
            *outdatedp = 1;
out:  __os_free(dbenv, name);
      return (ret);
}

/*
 * __log_zero --
 *    Zero out the tail of a log after a truncate.
 */
static int
__log_zero(dbenv, from_lsn, to_lsn)
      DB_ENV *dbenv;
      DB_LSN *from_lsn, *to_lsn;
{
      char *lname;
      DB_LOG *dblp;
      LOG *lp;
      int ret;
      size_t nbytes, len, nw;
      u_int8_t buf[4096];
      u_int32_t mbytes, bytes;

      dblp = dbenv->lg_handle;
      lp = (LOG *)dblp->reginfo.primary;
      lname = NULL;

      if (dblp->lfname != lp->lsn.file) {
            if (F_ISSET(&dblp->lfh, DB_FH_VALID))
                  (void)__os_closehandle(dbenv, &dblp->lfh);
            dblp->lfname = lp->lsn.file;
      }

      if (from_lsn->file != to_lsn->file) {
            /* We removed some log files; have to 0 to end of file. */
            if (!F_ISSET(&dblp->lfh, DB_FH_VALID) && (ret =
                __log_name(dblp, dblp->lfname, &lname, &dblp->lfh, 0)) != 0)
                  return (ret);
            if ((ret = __os_ioinfo(dbenv,
                NULL, &dblp->lfh, &mbytes, &bytes, NULL)) != 0)
                  goto err;
            len = mbytes * MEGABYTE + bytes - from_lsn->offset;
      } else if (to_lsn->offset <= from_lsn->offset)
            return (0);
      else
            len = to_lsn->offset = from_lsn->offset;

      memset(buf, 0, sizeof(buf));

      /* Initialize the write position. */
      if (!F_ISSET(&dblp->lfh, DB_FH_VALID) &&
          (ret = __log_name(dblp, dblp->lfname, &lname, &dblp->lfh, 0)) != 0)
            goto err;

      if ((ret = __os_seek(dbenv,
          &dblp->lfh, 0, 0, from_lsn->offset, 0, DB_OS_SEEK_SET)) != 0)
            return (ret);

      while (len > 0) {
            nbytes = len > sizeof(buf) ? sizeof(buf) : len;
            if ((ret =
                __os_write(dbenv, &dblp->lfh, buf, nbytes, &nw)) != 0)
                  return (ret);
            len -= nbytes;
      }
err:  if (lname != NULL)
            __os_free(dbenv, lname);

      return (0);
}

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