Обсуждение: Re: [HACKERS] pg_resetxlog -r flag

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Re: [HACKERS] pg_resetxlog -r flag

От
Bruce Momjian
Дата:
[ FYI, my previous email mentioned -f, while the feature is -r.]

Bruce Momjian wrote:
> A month ago, pg_resetxlog got an -r flag:
>
>   -r    restore the pg_control file from old XLog files,
>         resets is not done.
>
> However, the patch had identifiable problems that are still not fixed:
>
>     http://archives.postgresql.org/pgsql-hackers/2006-05/msg00013.php
>
> Unless these problems are fixed in the next few days, the patch will be
> reverted.

No one has fixed the patch, so I am removing it.  There is a memory leak
in the code, a missing lock, and it needs to be better designed.  If
anyone wants to update the patch and resubmit it, please go ahead.  The
problem are listed in this thread:

    http://archives.postgresql.org/pgsql-hackers/2006-05/msg00002.php

--
  Bruce Momjian   http://candle.pha.pa.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
Index: doc/src/sgml/ref/pg_resetxlog.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v
retrieving revision 1.14
diff -c -c -r1.14 pg_resetxlog.sgml
*** doc/src/sgml/ref/pg_resetxlog.sgml    26 Apr 2006 02:17:15 -0000    1.14
--- doc/src/sgml/ref/pg_resetxlog.sgml    1 Jun 2006 22:48:36 -0000
***************
*** 20,26 ****
     <command>pg_resetxlog</command>
     <arg>-f</arg>
     <arg>-n</arg>
-    <arg>-r</arg>
     <arg>-o<replaceable class="parameter">oid</replaceable> </arg>
     <arg>-x <replaceable class="parameter">xid</replaceable> </arg>
     <arg>-m <replaceable class="parameter">mxid</replaceable> </arg>
--- 20,25 ----
***************
*** 58,79 ****

    <para>
     If <command>pg_resetxlog</command> complains that it cannot determine
!    valid data for <filename>pg_control</>, you can force it to proceed
!    anyway by specifying the <literal>-f</> (force) switch. In this case
!    plausible values will be substituted for the missing data.
!    <command>pg_resetxlog</command>'s own environment is the source for
!    its guess at the locale fields; take care that <envar>LANG</> and so
!    forth match the environment that <command>initdb</> was run in.
!    <filename>/xlog</> files are used to determine other parameters, like
!    next OID, next transaction ID, next multi-transaction ID and offset,
!    WAL starting address, and database locale fields. Because determined
!    values might be wrong, the first five of these can be set using the
!    switches discussed below. If you are not able to determine correct
!    values for all these fields, <literal>-f</> can still be used, but
     the recovered database must be treated with even more suspicion than
!    usual: an immediate dump and reload is imperative. <emphasis>Do
!    not</> execute any data-modifying operations in the database before
!    you dump; as any such action is likely to make the corruption worse.
    </para>

    <para>
--- 57,78 ----

    <para>
     If <command>pg_resetxlog</command> complains that it cannot determine
!    valid data for <filename>pg_control</>, you can force it to proceed anyway
!    by specifying the <literal>-f</> (force) switch.  In this case plausible
!    values will be substituted for the missing data.  Most of the fields can be
!    expected to match, but manual assistance may be needed for the next OID,
!    next transaction ID, next multitransaction ID and offset,
!    WAL starting address, and database locale fields.
!    The first five of these can be set using the switches discussed below.
!    <command>pg_resetxlog</command>'s own environment is the source for its
!    guess at the locale fields; take care that <envar>LANG</> and so forth
!    match the environment that <command>initdb</> was run in.
!    If you are not able to determine correct values for all these fields,
!    <literal>-f</> can still be used, but
     the recovered database must be treated with even more suspicion than
!    usual: an immediate dump and reload is imperative.  <emphasis>Do not</>
!    execute any data-modifying operations in the database before you dump;
!    as any such action is likely to make the corruption worse.
    </para>

    <para>
***************
*** 151,161 ****
    </para>

    <para>
-    The <literal>-r</> restores <filename>pg_control</> counters listed
-    above without resetting the write-ahead log.
-   </para>
-
-   <para>
     The <literal>-n</> (no operation) switch instructs
     <command>pg_resetxlog</command> to print the values reconstructed from
     <filename>pg_control</> and then exit without modifying anything.
--- 150,155 ----
Index: src/bin/pg_resetxlog/pg_resetxlog.c
===================================================================
RCS file: /cvsroot/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v
retrieving revision 1.46
diff -c -c -r1.46 pg_resetxlog.c
*** src/bin/pg_resetxlog/pg_resetxlog.c    26 Apr 2006 21:52:31 -0000    1.46
--- src/bin/pg_resetxlog/pg_resetxlog.c    1 Jun 2006 22:48:37 -0000
***************
*** 4,32 ****
   *      A utility to "zero out" the xlog when it's corrupt beyond recovery.
   *      Can also rebuild pg_control if needed.
   *
!  * The theory of reset operation is fairly simple:
   *      1. Read the existing pg_control (which will include the last
   *         checkpoint record).  If it is an old format then update to
   *         current format.
!  *      2. If pg_control is corrupt, attempt to rebuild the values,
!  *         by scanning the old xlog; if it fail then try to guess it.
   *      3. Modify pg_control to reflect a "shutdown" state with a checkpoint
   *         record at the start of xlog.
   *      4. Flush the existing xlog files and write a new segment with
   *         just a checkpoint record in it.  The new segment is positioned
   *         just past the end of the old xlog, so that existing LSNs in
   *         data pages will appear to be "in the past".
   *
!  * The algorithm of restoring the pg_control value from old xlog file:
!  *    1. Retrieve all of the active xlog files from xlog direcotry into a list
!  *       by increasing order, according their timeline, log id, segment id.
!  *    2. Search the list to find the oldest xlog file of the lastest time line.
!  *    3. Search the records from the oldest xlog file of latest time line
!  *       to the latest xlog file of latest time line, if the checkpoint record
!  *       has been found, update the latest checkpoint and previous checkpoint.
!  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   *-------------------------------------------------------------------------
   */
--- 4,29 ----
   *      A utility to "zero out" the xlog when it's corrupt beyond recovery.
   *      Can also rebuild pg_control if needed.
   *
!  * The theory of operation is fairly simple:
   *      1. Read the existing pg_control (which will include the last
   *         checkpoint record).  If it is an old format then update to
   *         current format.
!  *      2. If pg_control is corrupt, attempt to intuit reasonable values,
!  *         by scanning the old xlog if necessary.
   *      3. Modify pg_control to reflect a "shutdown" state with a checkpoint
   *         record at the start of xlog.
   *      4. Flush the existing xlog files and write a new segment with
   *         just a checkpoint record in it.  The new segment is positioned
   *         just past the end of the old xlog, so that existing LSNs in
   *         data pages will appear to be "in the past".
+  * This is all pretty straightforward except for the intuition part of
+  * step 2 ...
   *
!  *
!  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
+  * $PostgreSQL: pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.43 2006/04/05 03:34:05 tgl Exp $
   *
   *-------------------------------------------------------------------------
   */
***************
*** 49,57 ****
  #include "catalog/catversion.h"
  #include "catalog/pg_control.h"

- #define GUESS    0
- #define WAL    1
-
  extern int    optind;
  extern char *optarg;

--- 46,51 ----
***************
*** 59,133 ****
  static ControlFileData ControlFile;        /* pg_control values */
  static uint32 newXlogId,
              newXlogSeg;            /* ID/Segment of new XLOG segment */
  static const char *progname;
- static uint64        sysidentifier=-1;
-
- /*
-  * We use a list to store the active xlog files we had found in the
-  * xlog directory in increasing order according the time line, logid,
-  * segment id.
-  *
-  */
- typedef struct XLogFileName {
-     TimeLineID tli;
-     uint32 logid;
-     uint32 seg;
-     char fname[256];
-     struct XLogFileName *next;
- }    XLogFileName;
-
- /* The list head */
- static XLogFileName *xlogfilelist=NULL;
-
- /* LastXLogfile is the latest file in the latest time line,
-    CurXLogfile is the oldest file in the lastest time line
-    */
- static XLogFileName *CurXLogFile, *LastXLogFile;
-
- /* The last checkpoint found in xlog file.*/
- static CheckPoint      lastcheckpoint;
-
- /* The last and previous checkpoint pointers found in xlog file.*/
- static XLogRecPtr     prevchkp, lastchkp;
-
- /* the database state.*/
- static DBState    state=DB_SHUTDOWNED;
-
- /* the total checkpoint numbers which had been found in the xlog file.*/
- static int         found_checkpoint=0;
-

  static bool ReadControlFile(void);
! static bool RestoreControlValues(int mode);
! static void PrintControlValues(void);
! static void UpdateCtlFile4Reset(void);
  static void RewriteControlFile(void);
  static void KillExistingXLOG(void);
  static void WriteEmptyXLOG(void);
  static void usage(void);

- static void GetXLogFiles(void);
- static bool ValidXLogFileName(char * fname);
- static bool ValidXLogFileHeader(XLogFileName *segfile);
- static bool ValidXLOGPageHeader(XLogPageHeader hdr, uint32 tli, uint32 id, uint32 seg);
- static bool CmpXLogFileOT(XLogFileName * f1, XLogFileName *f2);
- static bool IsNextSeg(XLogFileName *prev, XLogFileName *cur);
- static void InsertXLogFile( char * fname );
- static bool ReadXLogPage(void);
- static bool RecordIsValid(XLogRecord *record, XLogRecPtr recptr);
- static bool FetchRecord(void);
- static void UpdateCheckPoint(XLogRecord *record);
- static void SelectStartXLog(void);
- static int SearchLastCheckpoint(void);
- static int OpenXLogFile(XLogFileName *sf);
- static void CleanUpList(XLogFileName *list);

  int
  main(int argc, char *argv[])
  {
      int            c;
      bool        force = false;
-     bool        restore = false;
      bool        noupdate = false;
      TransactionId set_xid = 0;
      Oid            set_oid = 0;
--- 53,75 ----
  static ControlFileData ControlFile;        /* pg_control values */
  static uint32 newXlogId,
              newXlogSeg;            /* ID/Segment of new XLOG segment */
+ static bool guessed = false;    /* T if we had to guess at any values */
  static const char *progname;

  static bool ReadControlFile(void);
! static void GuessControlValues(void);
! static void PrintControlValues(bool guessed);
  static void RewriteControlFile(void);
  static void KillExistingXLOG(void);
  static void WriteEmptyXLOG(void);
  static void usage(void);


  int
  main(int argc, char *argv[])
  {
      int            c;
      bool        force = false;
      bool        noupdate = false;
      TransactionId set_xid = 0;
      Oid            set_oid = 0;
***************
*** 142,150 ****
      char       *DataDir;
      int            fd;
      char        path[MAXPGPATH];
!     bool        ctlcorrupted = false;
!     bool        PidLocked = false;
!
      set_pglocale_pgservice(argv[0], "pg_resetxlog");

      progname = get_progname(argv[0]);
--- 84,90 ----
      char       *DataDir;
      int            fd;
      char        path[MAXPGPATH];
!
      set_pglocale_pgservice(argv[0], "pg_resetxlog");

      progname = get_progname(argv[0]);
***************
*** 164,181 ****
      }


!     while ((c = getopt(argc, argv, "fl:m:no:O:x:r")) != -1)
      {
          switch (c)
          {
              case 'f':
                  force = true;
                  break;
!
!             case 'r':
!                 restore = true;
!                 break;
!
              case 'n':
                  noupdate = true;
                  break;
--- 104,117 ----
      }


!     while ((c = getopt(argc, argv, "fl:m:no:O:x:")) != -1)
      {
          switch (c)
          {
              case 'f':
                  force = true;
                  break;
!
              case 'n':
                  noupdate = true;
                  break;
***************
*** 319,335 ****
      }
      else
      {
!         PidLocked = true;
      }

      /*
       * Attempt to read the existing pg_control file
       */
      if (!ReadControlFile())
!     {
!         /* The control file has been corruptted.*/
!         ctlcorrupted = true;
!     }

      /*
       * Adjust fields if required by switches.  (Do this now so that printout,
--- 255,271 ----
      }
      else
      {
!         fprintf(stderr, _("%s: lock file \"%s\" exists\n"
!                           "Is a server running?  If not, delete the lock file and try again.\n"),
!                 progname, path);
!         exit(1);
      }

      /*
       * Attempt to read the existing pg_control file
       */
      if (!ReadControlFile())
!         GuessControlValues();

      /*
       * Adjust fields if required by switches.  (Do this now so that printout,
***************
*** 358,438 ****
          ControlFile.logSeg = minXlogSeg;
      }

-     /* retore the broken control file from WAL file.*/
-     if (restore)
-     {
-
-         /* If the control fine is fine, don't touch it.*/
-         if ( !ctlcorrupted )
-         {
-             printf(_("\nThe control file seems fine, not need to restore it.\n"));
-             printf(_("If you want to restore it anyway, use -f option, but this also will reset the log file.\n"));
-             exit(0);
-         }
-
-
-         /* Try to restore control values from old xlog file, or complain it.*/
-         if (RestoreControlValues(WAL))
-         {
-             /* Success in restoring the checkpoint information from old xlog file.*/
-
-             /* Print it out.*/
-             PrintControlValues();
-
-             /* In case the postmaster is crashed.
-              * But it may be dangerous for the living one.
-              * It may need a more good way.
-              */
-             if (PidLocked)
-             {
-                 ControlFile.state = DB_IN_PRODUCTION;
-             }
-             /* Write the new control file. */
-             RewriteControlFile();
-             printf(_("\nThe control file had been restored.\n"));
-         }
-         else
-         {
-             /* Fail in restoring the checkpoint information from old xlog file. */
-             printf(_("\nCan not restore the control file from XLog file..\n"));
-             printf(_("\nIf you want to restore it anyway, use -f option to guess the information, but this also will
resetthe log file.\n")); 
-         }
-
-         exit(0);
-
-     }
-     if (PidLocked)
-     {
-         fprintf(stderr, _("%s: lock file \"%s\" exists\n"
-                           "Is a server running?  If not, delete the lock file and try again.\n"),
-                 progname, path);
-         exit(1);
-
-     }
      /*
!     * Print out the values in control file if -n is given. if the control file is
!     * corrupted, then inform user to restore it first.
       */
!     if (noupdate)
      {
!         if (!ctlcorrupted)
          {
!             /* The control file is fine, print the values out.*/
!             PrintControlValues();
!             exit(0);
!         }
!         else{
!             /* The control file is corrupted.*/
!             printf(_("The control file had been corrupted.\n"));
!             printf(_("Please use -r option to restore it first.\n"));
              exit(1);
!             }
      }

      /*
       * Don't reset from a dirty pg_control without -f, either.
       */
!     if (ControlFile.state != DB_SHUTDOWNED && !force && !ctlcorrupted)
      {
          printf(_("The database server was not shut down cleanly.\n"
                   "Resetting the transaction log may cause data to be lost.\n"
--- 294,319 ----
          ControlFile.logSeg = minXlogSeg;
      }

      /*
!      * If we had to guess anything, and -f was not given, just print the
!      * guessed values and exit.  Also print if -n is given.
       */
!     if ((guessed && !force) || noupdate)
      {
!         PrintControlValues(guessed);
!         if (!noupdate)
          {
!             printf(_("\nIf these values seem acceptable, use -f to force reset.\n"));
              exit(1);
!         }
!         else
!             exit(0);
      }

      /*
       * Don't reset from a dirty pg_control without -f, either.
       */
!     if (ControlFile.state != DB_SHUTDOWNED && !force)
      {
          printf(_("The database server was not shut down cleanly.\n"
                   "Resetting the transaction log may cause data to be lost.\n"
***************
*** 440,474 ****
          exit(1);
      }

! /*
!      * Try to reset the xlog file.
       */
-
-     /* If the control file is corrupted, and -f option is given, resotre it first.*/
-     if ( ctlcorrupted )
-     {
-         if (force)
-         {
-             if (!RestoreControlValues(WAL))
-             {
-                 printf(_("fails to recover the control file from old xlog files, so we had to guess it.\n"));
-                 RestoreControlValues(GUESS);
-             }
-             printf(_("Restored the control file from old xlog files.\n"));
-         }
-         else
-         {
-             printf(_("Control file corrupted.\nIf you want to proceed anyway, use -f to force reset.\n"));
-             exit(1);
-             }
-     }
-
-     /* Reset the xlog fille.*/
-     UpdateCtlFile4Reset();
      RewriteControlFile();
      KillExistingXLOG();
      WriteEmptyXLOG();
!     printf(_("Transaction log reset\n"));
      return 0;
  }

--- 321,334 ----
          exit(1);
      }

!     /*
!      * Else, do the dirty deed.
       */
      RewriteControlFile();
      KillExistingXLOG();
      WriteEmptyXLOG();
!
!     printf(_("Transaction log reset\n"));
      return 0;
  }

***************
*** 537,542 ****
--- 397,403 ----
                  progname);
          /* We will use the data anyway, but treat it as guessed. */
          memcpy(&ControlFile, buffer, sizeof(ControlFile));
+         guessed = true;
          return true;
      }

***************
*** 547,631 ****
  }


-
-
  /*
!  *  Restore the pg_control values by scanning old xlog files or by guessing it.
!  *
!  * Input parameter:
!  *    WAL:  Restore the pg_control values by scanning old xlog files.
!  *    GUESS: Restore the pg_control values by guessing.
!  * Return:
!  *    TRUE: success in restoring.
!  *    FALSE: fail to restore the values.
!  *
   */
! static bool
! RestoreControlValues(int mode)
  {
      struct timeval tv;
      char       *localeptr;
-     bool    successed = true;

      /*
       * Set up a completely default set of pg_control values.
       */
      memset(&ControlFile, 0, sizeof(ControlFile));

      ControlFile.pg_control_version = PG_CONTROL_VERSION;
      ControlFile.catalog_version_no = CATALOG_VERSION_NO;

!     /*
!      * update the checkpoint value in control file,by searching
!      * xlog segment file, or just guessing it.
       */
!     if (mode == WAL)
!     {
!         int result = SearchLastCheckpoint();

!         if (result > 0) /* The last checkpoint had been found. */
!         {
!             ControlFile.checkPointCopy = lastcheckpoint;
!             ControlFile.checkPointCopy.ThisTimeLineID = LastXLogFile->tli;
!             ControlFile.checkPoint = lastchkp;
!             ControlFile.prevCheckPoint = prevchkp;
!
!             ControlFile.logId = LastXLogFile->logid;
!             ControlFile.logSeg = LastXLogFile->seg + 1;
!             ControlFile.state = state;
!         }
!         else
!             successed = false;
!
!         /* Clean up the list. */
!         CleanUpList(xlogfilelist);
!     }
!     else    /* GUESS */
!     {
!         ControlFile.checkPointCopy.ThisTimeLineID = 2;
!         ControlFile.checkPointCopy.redo.xlogid = 0;
!         ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogLongPHD;
!         ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
!         ControlFile.checkPointCopy.nextXid = (TransactionId) 514;    /* XXX */
!         ControlFile.checkPointCopy.nextOid = FirstBootstrapObjectId;
!         ControlFile.checkPointCopy.nextMulti = FirstMultiXactId;
!         ControlFile.checkPointCopy.nextMultiOffset = 0;
!         ControlFile.checkPointCopy.time = time(NULL);
!         ControlFile.checkPoint = ControlFile.checkPointCopy.redo;

!         /*
!          * Create a new unique installation identifier, since we can no longer
!          * use any old XLOG records.  See notes in xlog.c about the algorithm.
!          */
!         gettimeofday(&tv, NULL);
!         sysidentifier = ((uint64) tv.tv_sec) << 32;
!         sysidentifier |= (uint32) (tv.tv_sec | tv.tv_usec);
!         ControlFile.state = DB_SHUTDOWNED;
!
!     }

      ControlFile.time = time(NULL);
!     ControlFile.system_identifier = sysidentifier;
      ControlFile.maxAlign = MAXIMUM_ALIGNOF;
      ControlFile.floatFormat = FLOATFORMAT_VALUE;
      ControlFile.blcksz = BLCKSZ;
--- 408,458 ----
  }


  /*
!  * Guess at pg_control values when we can't read the old ones.
   */
! static void
! GuessControlValues(void)
  {
+     uint64        sysidentifier;
      struct timeval tv;
      char       *localeptr;

      /*
       * Set up a completely default set of pg_control values.
       */
+     guessed = true;
      memset(&ControlFile, 0, sizeof(ControlFile));

      ControlFile.pg_control_version = PG_CONTROL_VERSION;
      ControlFile.catalog_version_no = CATALOG_VERSION_NO;

!     /*
!      * Create a new unique installation identifier, since we can no longer use
!      * any old XLOG records.  See notes in xlog.c about the algorithm.
       */
!     gettimeofday(&tv, NULL);
!     sysidentifier = ((uint64) tv.tv_sec) << 32;
!     sysidentifier |= (uint32) (tv.tv_sec | tv.tv_usec);

!     ControlFile.system_identifier = sysidentifier;

!     ControlFile.checkPointCopy.redo.xlogid = 0;
!     ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogLongPHD;
!     ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
!     ControlFile.checkPointCopy.ThisTimeLineID = 1;
!     ControlFile.checkPointCopy.nextXid = (TransactionId) 514;    /* XXX */
!     ControlFile.checkPointCopy.nextOid = FirstBootstrapObjectId;
!     ControlFile.checkPointCopy.nextMulti = FirstMultiXactId;
!     ControlFile.checkPointCopy.nextMultiOffset = 0;
!     ControlFile.checkPointCopy.time = time(NULL);

+     ControlFile.state = DB_SHUTDOWNED;
      ControlFile.time = time(NULL);
!     ControlFile.logId = 0;
!     ControlFile.logSeg = 1;
!     ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
!
      ControlFile.maxAlign = MAXIMUM_ALIGNOF;
      ControlFile.floatFormat = FLOATFORMAT_VALUE;
      ControlFile.blcksz = BLCKSZ;
***************
*** 648,654 ****
          exit(1);
      }
      StrNCpy(ControlFile.lc_collate, localeptr, LOCALE_NAME_BUFLEN);
-
      localeptr = setlocale(LC_CTYPE, "");
      if (!localeptr)
      {
--- 475,480 ----
***************
*** 657,678 ****
      }
      StrNCpy(ControlFile.lc_ctype, localeptr, LOCALE_NAME_BUFLEN);

!     return successed;
  }


  /*
!  * Print the out pg_control values.
   *
   * NB: this display should be just those fields that will not be
   * reset by RewriteControlFile().
   */
  static void
! PrintControlValues(void)
  {
      char        sysident_str[32];

!     printf(_("pg_control values:\n\n"));

      /*
       * Format system_identifier separately to keep platform-dependent format
--- 483,510 ----
      }
      StrNCpy(ControlFile.lc_ctype, localeptr, LOCALE_NAME_BUFLEN);

!     /*
!      * XXX eventually, should try to grovel through old XLOG to develop more
!      * accurate values for TimeLineID, nextXID, etc.
!      */
  }


  /*
!  * Print the guessed pg_control values when we had to guess.
   *
   * NB: this display should be just those fields that will not be
   * reset by RewriteControlFile().
   */
  static void
! PrintControlValues(bool guessed)
  {
      char        sysident_str[32];

!     if (guessed)
!         printf(_("Guessed pg_control values:\n\n"));
!     else
!         printf(_("pg_control values:\n\n"));

      /*
       * Format system_identifier separately to keep platform-dependent format
***************
*** 706,717 ****
      printf(_("LC_CTYPE:                             %s\n"), ControlFile.lc_ctype);
  }

  /*
! * Update the control file before reseting it.
! */
! static void
! UpdateCtlFile4Reset(void)
  {
      /*
       * Adjust fields as needed to force an empty XLOG starting at the next
       * available segment.
--- 538,553 ----
      printf(_("LC_CTYPE:                             %s\n"), ControlFile.lc_ctype);
  }

+
  /*
!  * Write out the new pg_control file.
!  */
! static void
! RewriteControlFile(void)
  {
+     int            fd;
+     char        buffer[PG_CONTROL_SIZE]; /* need not be aligned */
+
      /*
       * Adjust fields as needed to force an empty XLOG starting at the next
       * available segment.
***************
*** 742,758 ****
      ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
      ControlFile.prevCheckPoint.xlogid = 0;
      ControlFile.prevCheckPoint.xrecoff = 0;
- }
-
- /*
-  * Write out the new pg_control file.
-  */
- static void
- RewriteControlFile(void)
- {
-     int            fd;
-     char        buffer[PG_CONTROL_SIZE]; /* need not be aligned */
-

      /* Contents are protected with a CRC */
      INIT_CRC32(ControlFile.crc);
--- 578,583 ----
***************
*** 847,852 ****
--- 672,678 ----
          errno = 0;
      }
  #ifdef WIN32
+
      /*
       * This fix is in mingw cvs (runtime/mingwex/dirent.c rev 1.4), but not in
       * released version
***************
*** 975,1638 ****
      printf(_("%s resets the PostgreSQL transaction log.\n\n"), progname);
      printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
      printf(_("Options:\n"));
!     printf(_("  -f              force reset xlog to be done, if the control file is corrupted, then try to restore
it.\n"));
!     printf(_("  -r              restore the pg_control file from old XLog files, resets is not done..\n"));
      printf(_("  -l TLI,FILE,SEG force minimum WAL starting location for new transaction log\n"));
!     printf(_("  -n              show extracted control values of existing pg_control file.\n"));
!     printf(_("  -m multiXID     set next multi transaction ID\n"));
      printf(_("  -o OID          set next OID\n"));
!     printf(_("  -O multiOffset  set next multi transaction offset\n"));
      printf(_("  -x XID          set next transaction ID\n"));
      printf(_("  --help          show this help, then exit\n"));
      printf(_("  --version       output version information, then exit\n"));
      printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
  }
-
-
-
- /*
-  * The following routines are mainly used for getting pg_control values
-  * from the xlog file.
-  */
-
-  /* some local varaibles.*/
- static int              logFd=0; /* kernel FD for current input file */
- static int              logRecOff;      /* offset of next record in page */
- static char             pageBuffer[BLCKSZ];     /* current page */
- static XLogRecPtr       curRecPtr;      /* logical address of current record */
- static XLogRecPtr       prevRecPtr;     /* logical address of previous record */
- static char             *readRecordBuf = NULL; /* ReadRecord result area */
- static uint32           readRecordBufSize = 0;
- static int32            logPageOff;     /* offset of current page in file */
- static uint32           logId;          /* current log file id */
- static uint32           logSeg;         /* current log file segment */
- static uint32           logTli;         /* current log file timeline */
-
- /*
-  * Get existing XLOG files
-  */
- static void
- GetXLogFiles(void)
- {
-     DIR           *xldir;
-     struct dirent *xlde;
-
-     /* Open the xlog direcotry.*/
-     xldir = opendir(XLOGDIR);
-     if (xldir == NULL)
-     {
-         fprintf(stderr, _("%s: could not open directory \"%s\": %s\n"),
-                 progname, XLOGDIR, strerror(errno));
-         exit(1);
-     }
-
-     /* Search the directory, insert the segment files into the xlogfilelist.*/
-     errno = 0;
-     while ((xlde = readdir(xldir)) != NULL)
-     {
-         if (ValidXLogFileName(xlde->d_name)) {
-             /* XLog file is found, insert it into the xlogfilelist.*/
-             InsertXLogFile(xlde->d_name);
-         };
-         errno = 0;
-     }
- #ifdef WIN32
-     if (GetLastError() == ERROR_NO_MORE_FILES)
-         errno = 0;
- #endif
-
-     if (errno)
-     {
-         fprintf(stderr, _("%s: could not read from directory \"%s\": %s\n"),
-                 progname, XLOGDIR, strerror(errno));
-         exit(1);
-     }
-     closedir(xldir);
- }
-
- /*
-  * Insert a file while had been found in the xlog folder into xlogfilelist.
-  * The xlogfile list is matained in a increasing order.
-  *
-  * The input parameter is the name of the xlog  file, the name is assumpted
-  * valid.
-  */
- static void
- InsertXLogFile( char * fname )
- {
-     XLogFileName * NewSegFile, *Curr, *Prev;
-     bool append2end = false;
-
-     /* Allocate a new node for the new file. */
-     NewSegFile = (XLogFileName *) malloc(sizeof(XLogFileName));
-     strcpy(NewSegFile->fname,fname); /* setup the name */
-     /* extract the time line, logid, and segment number from the name.*/
-     sscanf(fname, "%8x%8x%8x", &(NewSegFile->tli), &(NewSegFile->logid), &(NewSegFile->seg));
-     NewSegFile->next = NULL;
-
-     /* Ensure the xlog file is active and valid.*/
-     if (! ValidXLogFileHeader(NewSegFile))
-     {
-         free(NewSegFile);
-         return;
-     }
-
-     /* the list is empty.*/
-     if ( xlogfilelist == NULL ) {
-         xlogfilelist = NewSegFile;
-         return;
-     };
-
-     /* try to search the list and find the insert point. */
-     Prev=Curr=xlogfilelist;
-     while( CmpXLogFileOT(NewSegFile, Curr))
-     {
-         /* the node is appended to the end of the list.*/
-         if (Curr->next == NULL)
-         {
-             append2end = true;
-             break;
-         }
-         Prev=Curr;
-         Curr = Curr->next;
-     }
-
-     /* Insert the new node to the list.*/
-     if ( append2end )
-     {
-         /* We need to append the new node to the end of the list */
-         Curr->next = NewSegFile;
-     }
-     else
-     {
-         NewSegFile->next = Curr;
-         /* prev should not be the list head. */
-         if ( Prev != NULL && Prev != xlogfilelist)
-         {
-             Prev->next = NewSegFile;
-         }
-     }
-     /* Update the list head if it is needed.*/
-     if ((Curr == xlogfilelist) && !append2end)
-     {
-         xlogfilelist = NewSegFile;
-     }
-
- }
-
- /*
-  * compare two xlog file from their name to see which one is latest.
-  *
-  * Return true for file 2 is the lastest file.
-  *
-  */
- static bool
- CmpXLogFileOT(XLogFileName * f1, XLogFileName *f2)
- {
-         if (f2->tli >= f1->tli)
-         {
-                 if (f2->logid >= f1->logid)
-                 {
-                         if (f2->seg > f1->seg) return false;
-                 }
-         }
-         return true;
-
- }
-
- /* check is two segment file is continous.*/
- static bool
- IsNextSeg(XLogFileName *prev, XLogFileName *cur)
- {
-     uint32 logid, logseg;
-
-     if (prev->tli != cur->tli) return false;
-
-     logid = prev->logid;
-     logseg = prev->seg;
-     NextLogSeg(logid, logseg);
-
-     if ((logid == cur->logid) && (logseg == cur->seg)) return true;
-
-     return false;
-
- }
-
-
- /*
- * Select the oldest xlog file in the latest time line.
- */
- static void
- SelectStartXLog( void )
- {
-     XLogFileName *tmp;
-     CurXLogFile = xlogfilelist;
-
-     if (xlogfilelist == NULL)
-     {
-         return;
-     }
-
-     tmp=LastXLogFile=CurXLogFile=xlogfilelist;
-
-     while(tmp->next != NULL)
-     {
-
-         /*
-          * we should ensure that from the first to
-          * the last segment file is continous.
-          * */
-         if (!IsNextSeg(tmp, tmp->next))
-         {
-             CurXLogFile = tmp->next;
-         }
-         tmp=tmp->next;
-     }
-
-     LastXLogFile = tmp;
-
- }
-
- /*
-  * Check if the file is a valid xlog file.
-  *
-  * Return true for the input file is a valid xlog file.
-  *
-  * The input parameter is the name of the xlog file.
-  *
-  */
- static bool
- ValidXLogFileName(char * fname)
- {
-     uint32 logTLI, logId, logSeg;
-     if (strlen(fname) != 24 ||
-         strspn(fname, "0123456789ABCDEF") != 24 ||
-         sscanf(fname, "%8x%8x%8x", &logTLI, &logId, &logSeg) != 3)
-         return false;
-     return true;
-
- }
-
- /* Ensure the xlog file is active and valid.*/
- static bool
- ValidXLogFileHeader(XLogFileName *segfile)
- {
-     int fd;
-     char buffer[BLCKSZ];
-     char        path[MAXPGPATH];
-     size_t nread;
-
-     snprintf(path, MAXPGPATH, "%s/%s", XLOGDIR, segfile->fname);
-     fd = open(path, O_RDONLY | PG_BINARY, 0);
-         if (fd < 0)
-     {
-         return false;
-     }
-     nread = read(fd, buffer, BLCKSZ);
-     if (nread == BLCKSZ)
-     {
-         XLogPageHeader hdr = (XLogPageHeader)buffer;
-
-         if (ValidXLOGPageHeader(hdr, segfile->tli, segfile->logid, segfile->seg))
-         {
-             return true;
-         }
-
-     }
-     return false;
-
- }
- static bool
- ValidXLOGPageHeader(XLogPageHeader hdr, uint32 tli, uint32 id, uint32 seg)
- {
-     XLogRecPtr    recaddr;
-
-     if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
-     {
-         return false;
-     }
-     if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
-     {
-         return false;
-     }
-     if (hdr->xlp_info & XLP_LONG_HEADER)
-     {
-         XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
-
-         if (longhdr->xlp_seg_size != XLogSegSize)
-         {
-             return false;
-         }
-         /* Get the system identifier from the segment file header.*/
-         sysidentifier = ((XLogLongPageHeader) pageBuffer)->xlp_sysid;
-     }
-
-     recaddr.xlogid = id;
-     recaddr.xrecoff = seg * XLogSegSize + logPageOff;
-     if (!XLByteEQ(hdr->xlp_pageaddr, recaddr))
-     {
-         return false;
-     }
-
-     if (hdr->xlp_tli != tli)
-     {
-         return false;
-     }
-     return true;
- }
-
-
- /* Read another page, if possible */
- static bool
- ReadXLogPage(void)
- {
-     size_t nread;
-
-     /* Need to advance to the new segment file.*/
-     if ( logPageOff >= XLogSegSize )
-     {
-         close(logFd);
-         logFd = 0;
-     }
-
-     /* Need to open the segement file.*/
-     if ((logFd <= 0) && (CurXLogFile != NULL))
-     {
-         if (OpenXLogFile(CurXLogFile) < 0)
-         {
-             return false;
-         }
-         CurXLogFile = CurXLogFile->next;
-     }
-
-     /* Read a page from the openning segement file.*/
-     nread = read(logFd, pageBuffer, BLCKSZ);
-
-     if (nread == BLCKSZ)
-     {
-         logPageOff += BLCKSZ;
-         if (ValidXLOGPageHeader( (XLogPageHeader)pageBuffer, logTli, logId, logSeg))
-             return true;
-     }
-
-     return false;
- }
-
- /*
-  * CRC-check an XLOG record.  We do not believe the contents of an XLOG
-  * record (other than to the minimal extent of computing the amount of
-  * data to read in) until we've checked the CRCs.
-  *
-  * We assume all of the record has been read into memory at *record.
-  */
- static bool
- RecordIsValid(XLogRecord *record, XLogRecPtr recptr)
- {
-     pg_crc32    crc;
-     int            i;
-     uint32        len = record->xl_len;
-     BkpBlock    bkpb;
-     char       *blk;
-
-     /* First the rmgr data */
-     INIT_CRC32(crc);
-     COMP_CRC32(crc, XLogRecGetData(record), len);
-
-     /* Add in the backup blocks, if any */
-     blk = (char *) XLogRecGetData(record) + len;
-     for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
-     {
-         uint32    blen;
-
-         if (!(record->xl_info & XLR_SET_BKP_BLOCK(i)))
-             continue;
-
-         memcpy(&bkpb, blk, sizeof(BkpBlock));
-         if (bkpb.hole_offset + bkpb.hole_length > BLCKSZ)
-         {
-             return false;
-         }
-         blen = sizeof(BkpBlock) + BLCKSZ - bkpb.hole_length;
-         COMP_CRC32(crc, blk, blen);
-         blk += blen;
-     }
-
-     /* Check that xl_tot_len agrees with our calculation */
-     if (blk != (char *) record + record->xl_tot_len)
-     {
-         return false;
-     }
-
-     /* Finally include the record header */
-     COMP_CRC32(crc, (char *) record + sizeof(pg_crc32),
-                SizeOfXLogRecord - sizeof(pg_crc32));
-     FIN_CRC32(crc);
-
-     if (!EQ_CRC32(record->xl_crc, crc))
-     {
-         return false;
-     }
-
-     return true;
- }
-
-
-
- /*
-  * Attempt to read an XLOG record into readRecordBuf.
-  */
- static bool
- FetchRecord(void)
- {
-     char       *buffer;
-     XLogRecord *record;
-     XLogContRecord *contrecord;
-     uint32        len, total_len;
-
-
-     while (logRecOff <= 0 || logRecOff > BLCKSZ - SizeOfXLogRecord)
-     {
-         /* Need to advance to new page */
-         if (! ReadXLogPage())
-         {
-             return false;
-         }
-
-         logRecOff = XLogPageHeaderSize((XLogPageHeader) pageBuffer);
-         if ((((XLogPageHeader) pageBuffer)->xlp_info & ~XLP_LONG_HEADER) != 0)
-         {
-             /* Check for a continuation record */
-             if (((XLogPageHeader) pageBuffer)->xlp_info & XLP_FIRST_IS_CONTRECORD)
-             {
-                 contrecord = (XLogContRecord *) (pageBuffer + logRecOff);
-                 logRecOff += MAXALIGN(contrecord->xl_rem_len + SizeOfXLogContRecord);
-             }
-         }
-     }
-
-     curRecPtr.xlogid = logId;
-     curRecPtr.xrecoff = logSeg * XLogSegSize + logPageOff + logRecOff;
-     record = (XLogRecord *) (pageBuffer + logRecOff);
-
-     if (record->xl_len == 0)
-     {
-         return false;
-     }
-
-     total_len = record->xl_tot_len;
-
-     /*
-      * Allocate or enlarge readRecordBuf as needed.  To avoid useless
-      * small increases, round its size to a multiple of BLCKSZ, and make
-      * sure it's at least 4*BLCKSZ to start with.  (That is enough for all
-      * "normal" records, but very large commit or abort records might need
-      * more space.)
-      */
-     if (total_len > readRecordBufSize)
-     {
-         uint32        newSize = total_len;
-
-         newSize += BLCKSZ - (newSize % BLCKSZ);
-         newSize = Max(newSize, 4 * BLCKSZ);
-         if (readRecordBuf)
-             free(readRecordBuf);
-         readRecordBuf = (char *) malloc(newSize);
-         if (!readRecordBuf)
-         {
-             readRecordBufSize = 0;
-             return false;
-         }
-         readRecordBufSize = newSize;
-     }
-
-     buffer = readRecordBuf;
-     len = BLCKSZ - curRecPtr.xrecoff % BLCKSZ; /* available in block */
-     if (total_len > len)
-     {
-         /* Need to reassemble record */
-         uint32            gotlen = len;
-
-         memcpy(buffer, record, len);
-         record = (XLogRecord *) buffer;
-         buffer += len;
-         for (;;)
-         {
-             uint32    pageHeaderSize;
-
-             if (!ReadXLogPage())
-             {
-                 return false;
-             }
-             if (!(((XLogPageHeader) pageBuffer)->xlp_info & XLP_FIRST_IS_CONTRECORD))
-             {
-                 return false;
-             }
-             pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) pageBuffer);
-             contrecord = (XLogContRecord *) (pageBuffer + pageHeaderSize);
-             if (contrecord->xl_rem_len == 0 ||
-                 total_len != (contrecord->xl_rem_len + gotlen))
-             {
-                 return false;
-             }
-             len = BLCKSZ - pageHeaderSize - SizeOfXLogContRecord;
-             if (contrecord->xl_rem_len > len)
-             {
-                 memcpy(buffer, (char *)contrecord + SizeOfXLogContRecord, len);
-                 gotlen += len;
-                 buffer += len;
-                 continue;
-             }
-             memcpy(buffer, (char *) contrecord + SizeOfXLogContRecord,
-                    contrecord->xl_rem_len);
-             logRecOff = MAXALIGN(pageHeaderSize + SizeOfXLogContRecord + contrecord->xl_rem_len);
-             break;
-         }
-         if (!RecordIsValid(record, curRecPtr))
-         {
-             return false;
-         }
-         return true;
-     }
-     /* Record is contained in this page */
-     memcpy(buffer, record, total_len);
-     record = (XLogRecord *) buffer;
-     logRecOff += MAXALIGN(total_len);
-     if (!RecordIsValid(record, curRecPtr))
-     {
-
-         return false;
-     }
-     return true;
- }
-
- /*
-  * if the record is checkpoint, update the lastest checkpoint record.
-  */
- static void
- UpdateCheckPoint(XLogRecord *record)
- {
-     uint8    info = record->xl_info & ~XLR_INFO_MASK;
-
-     if ((info == XLOG_CHECKPOINT_SHUTDOWN) ||
-         (info == XLOG_CHECKPOINT_ONLINE))
-     {
-          CheckPoint *chkpoint = (CheckPoint*) XLogRecGetData(record);
-          prevchkp = lastchkp;
-          lastchkp = curRecPtr;
-          lastcheckpoint = *chkpoint;
-
-          /* update the database state.*/
-          switch(info)
-          {
-             case XLOG_CHECKPOINT_SHUTDOWN:
-                 state = DB_SHUTDOWNED;
-                 break;
-             case XLOG_CHECKPOINT_ONLINE:
-                 state = DB_IN_PRODUCTION;
-                 break;
-          }
-          found_checkpoint ++ ;
-     }
- }
-
- static int
- OpenXLogFile(XLogFileName *sf)
- {
-
-     char        path[MAXPGPATH];
-
-     if ( logFd > 0 ) close(logFd);
-
-     /* Open a  Xlog segment file. */
-     snprintf(path, MAXPGPATH, "%s/%s", XLOGDIR, sf->fname);
-     logFd = open(path, O_RDONLY | PG_BINARY, 0);
-
-     if (logFd < 0)
-     {
-         fprintf(stderr, _("%s: Can not open xlog file %s.\n"), progname,path);
-         return -1;
-     }
-
-     /* Setup the parameter for searching. */
-     logPageOff = -BLCKSZ;        /* so 1st increment in readXLogPage gives 0 */
-     logRecOff = 0;
-     logId = sf->logid;
-     logSeg = sf->seg;
-     logTli = sf->tli;
-     return logFd;
- }
-
- /*
-  * Search the lastest checkpoint in the lastest XLog segment file.
-  *
-  * The return value is the total checkpoints which had been found
-  * in the XLog segment file.
-  */
- static int
- SearchLastCheckpoint(void)
- {
-
-     /* retrive all of the active xlog files from xlog direcotry
-      * into a list by increasing order, according their timeline,
-      * log id, segment id.
-     */
-     GetXLogFiles();
-
-     /* Select the oldest segment file in the lastest time line.*/
-     SelectStartXLog();
-
-     /* No segment file was found.*/
-     if ( CurXLogFile == NULL )
-     {
-         return 0;
-     }
-
-     /* initial it . */
-     logFd=logId=logSeg=logTli=0;
-
-     /*
-      * Search the XLog segment file from beginning to end,
-      * if checkpoint record is found, then update the
-      * latest check point.
-      */
-     while (FetchRecord())
-     {
-         /* To see if the record is checkpoint record. */
-         if (((XLogRecord *) readRecordBuf)->xl_rmid == RM_XLOG_ID)
-             UpdateCheckPoint((XLogRecord *) readRecordBuf);
-         prevRecPtr = curRecPtr;
-     }
-
-     /* We can not know clearly if we had reached the end.
-      * But just check if we reach the last segment file,
-      * if it is not, then some problem there.
-      * (We need a better way to know the abnormal broken during the search)
-      */
-     if ((logId != LastXLogFile->logid) && (logSeg != LastXLogFile->seg))
-     {
-         return 0;
-     }
-
-     /*
-      * return the checkpoints which had been found yet,
-      * let others know how much checkpointes are found.
-      */
-     return found_checkpoint;
- }
-
- /* Clean up the allocated list.*/
- static void
- CleanUpList(XLogFileName *list)
- {
-
-     XLogFileName *tmp;
-     tmp = list;
-     while(list != NULL)
-     {
-         tmp=list->next;
-         free(list);
-         list=tmp;
-     }
-
- }
-
--- 801,814 ----
      printf(_("%s resets the PostgreSQL transaction log.\n\n"), progname);
      printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
      printf(_("Options:\n"));
!     printf(_("  -f              force update to be done\n"));
      printf(_("  -l TLI,FILE,SEG force minimum WAL starting location for new transaction log\n"));
!     printf(_("  -m XID          set next multitransaction ID\n"));
!     printf(_("  -n              no update, just show extracted control values (for testing)\n"));
      printf(_("  -o OID          set next OID\n"));
!     printf(_("  -O OFFSET       set next multitransaction offset\n"));
      printf(_("  -x XID          set next transaction ID\n"));
      printf(_("  --help          show this help, then exit\n"));
      printf(_("  --version       output version information, then exit\n"));
      printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
  }
Index: doc/src/sgml/ref/pg_resetxlog.sgml
===================================================================
RCS file: /cvsroot/pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v
retrieving revision 1.14
diff -c -c -r1.14 pg_resetxlog.sgml
*** doc/src/sgml/ref/pg_resetxlog.sgml    26 Apr 2006 02:17:15 -0000    1.14
--- doc/src/sgml/ref/pg_resetxlog.sgml    1 Jun 2006 22:48:36 -0000
***************
*** 20,26 ****
     <command>pg_resetxlog</command>
     <arg>-f</arg>
     <arg>-n</arg>
-    <arg>-r</arg>
     <arg>-o<replaceable class="parameter">oid</replaceable> </arg>
     <arg>-x <replaceable class="parameter">xid</replaceable> </arg>
     <arg>-m <replaceable class="parameter">mxid</replaceable> </arg>
--- 20,25 ----
***************
*** 58,79 ****

    <para>
     If <command>pg_resetxlog</command> complains that it cannot determine
!    valid data for <filename>pg_control</>, you can force it to proceed
!    anyway by specifying the <literal>-f</> (force) switch. In this case
!    plausible values will be substituted for the missing data.
!    <command>pg_resetxlog</command>'s own environment is the source for
!    its guess at the locale fields; take care that <envar>LANG</> and so
!    forth match the environment that <command>initdb</> was run in.
!    <filename>/xlog</> files are used to determine other parameters, like
!    next OID, next transaction ID, next multi-transaction ID and offset,
!    WAL starting address, and database locale fields. Because determined
!    values might be wrong, the first five of these can be set using the
!    switches discussed below. If you are not able to determine correct
!    values for all these fields, <literal>-f</> can still be used, but
     the recovered database must be treated with even more suspicion than
!    usual: an immediate dump and reload is imperative. <emphasis>Do
!    not</> execute any data-modifying operations in the database before
!    you dump; as any such action is likely to make the corruption worse.
    </para>

    <para>
--- 57,78 ----

    <para>
     If <command>pg_resetxlog</command> complains that it cannot determine
!    valid data for <filename>pg_control</>, you can force it to proceed anyway
!    by specifying the <literal>-f</> (force) switch.  In this case plausible
!    values will be substituted for the missing data.  Most of the fields can be
!    expected to match, but manual assistance may be needed for the next OID,
!    next transaction ID, next multitransaction ID and offset,
!    WAL starting address, and database locale fields.
!    The first five of these can be set using the switches discussed below.
!    <command>pg_resetxlog</command>'s own environment is the source for its
!    guess at the locale fields; take care that <envar>LANG</> and so forth
!    match the environment that <command>initdb</> was run in.
!    If you are not able to determine correct values for all these fields,
!    <literal>-f</> can still be used, but
     the recovered database must be treated with even more suspicion than
!    usual: an immediate dump and reload is imperative.  <emphasis>Do not</>
!    execute any data-modifying operations in the database before you dump;
!    as any such action is likely to make the corruption worse.
    </para>

    <para>
***************
*** 151,161 ****
    </para>

    <para>
-    The <literal>-r</> restores <filename>pg_control</> counters listed
-    above without resetting the write-ahead log.
-   </para>
-
-   <para>
     The <literal>-n</> (no operation) switch instructs
     <command>pg_resetxlog</command> to print the values reconstructed from
     <filename>pg_control</> and then exit without modifying anything.
--- 150,155 ----
Index: src/bin/pg_resetxlog/pg_resetxlog.c
===================================================================
RCS file: /cvsroot/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v
retrieving revision 1.46
diff -c -c -r1.46 pg_resetxlog.c
*** src/bin/pg_resetxlog/pg_resetxlog.c    26 Apr 2006 21:52:31 -0000    1.46
--- src/bin/pg_resetxlog/pg_resetxlog.c    1 Jun 2006 22:48:37 -0000
***************
*** 4,32 ****
   *      A utility to "zero out" the xlog when it's corrupt beyond recovery.
   *      Can also rebuild pg_control if needed.
   *
!  * The theory of reset operation is fairly simple:
   *      1. Read the existing pg_control (which will include the last
   *         checkpoint record).  If it is an old format then update to
   *         current format.
!  *      2. If pg_control is corrupt, attempt to rebuild the values,
!  *         by scanning the old xlog; if it fail then try to guess it.
   *      3. Modify pg_control to reflect a "shutdown" state with a checkpoint
   *         record at the start of xlog.
   *      4. Flush the existing xlog files and write a new segment with
   *         just a checkpoint record in it.  The new segment is positioned
   *         just past the end of the old xlog, so that existing LSNs in
   *         data pages will appear to be "in the past".
   *
!  * The algorithm of restoring the pg_control value from old xlog file:
!  *    1. Retrieve all of the active xlog files from xlog direcotry into a list
!  *       by increasing order, according their timeline, log id, segment id.
!  *    2. Search the list to find the oldest xlog file of the lastest time line.
!  *    3. Search the records from the oldest xlog file of latest time line
!  *       to the latest xlog file of latest time line, if the checkpoint record
!  *       has been found, update the latest checkpoint and previous checkpoint.
!  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   *-------------------------------------------------------------------------
   */
--- 4,29 ----
   *      A utility to "zero out" the xlog when it's corrupt beyond recovery.
   *      Can also rebuild pg_control if needed.
   *
!  * The theory of operation is fairly simple:
   *      1. Read the existing pg_control (which will include the last
   *         checkpoint record).  If it is an old format then update to
   *         current format.
!  *      2. If pg_control is corrupt, attempt to intuit reasonable values,
!  *         by scanning the old xlog if necessary.
   *      3. Modify pg_control to reflect a "shutdown" state with a checkpoint
   *         record at the start of xlog.
   *      4. Flush the existing xlog files and write a new segment with
   *         just a checkpoint record in it.  The new segment is positioned
   *         just past the end of the old xlog, so that existing LSNs in
   *         data pages will appear to be "in the past".
+  * This is all pretty straightforward except for the intuition part of
+  * step 2 ...
   *
!  *
!  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
+  * $PostgreSQL: pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.43 2006/04/05 03:34:05 tgl Exp $
   *
   *-------------------------------------------------------------------------
   */
***************
*** 49,57 ****
  #include "catalog/catversion.h"
  #include "catalog/pg_control.h"

- #define GUESS    0
- #define WAL    1
-
  extern int    optind;
  extern char *optarg;

--- 46,51 ----
***************
*** 59,133 ****
  static ControlFileData ControlFile;        /* pg_control values */
  static uint32 newXlogId,
              newXlogSeg;            /* ID/Segment of new XLOG segment */
  static const char *progname;
- static uint64        sysidentifier=-1;
-
- /*
-  * We use a list to store the active xlog files we had found in the
-  * xlog directory in increasing order according the time line, logid,
-  * segment id.
-  *
-  */
- typedef struct XLogFileName {
-     TimeLineID tli;
-     uint32 logid;
-     uint32 seg;
-     char fname[256];
-     struct XLogFileName *next;
- }    XLogFileName;
-
- /* The list head */
- static XLogFileName *xlogfilelist=NULL;
-
- /* LastXLogfile is the latest file in the latest time line,
-    CurXLogfile is the oldest file in the lastest time line
-    */
- static XLogFileName *CurXLogFile, *LastXLogFile;
-
- /* The last checkpoint found in xlog file.*/
- static CheckPoint      lastcheckpoint;
-
- /* The last and previous checkpoint pointers found in xlog file.*/
- static XLogRecPtr     prevchkp, lastchkp;
-
- /* the database state.*/
- static DBState    state=DB_SHUTDOWNED;
-
- /* the total checkpoint numbers which had been found in the xlog file.*/
- static int         found_checkpoint=0;
-

  static bool ReadControlFile(void);
! static bool RestoreControlValues(int mode);
! static void PrintControlValues(void);
! static void UpdateCtlFile4Reset(void);
  static void RewriteControlFile(void);
  static void KillExistingXLOG(void);
  static void WriteEmptyXLOG(void);
  static void usage(void);

- static void GetXLogFiles(void);
- static bool ValidXLogFileName(char * fname);
- static bool ValidXLogFileHeader(XLogFileName *segfile);
- static bool ValidXLOGPageHeader(XLogPageHeader hdr, uint32 tli, uint32 id, uint32 seg);
- static bool CmpXLogFileOT(XLogFileName * f1, XLogFileName *f2);
- static bool IsNextSeg(XLogFileName *prev, XLogFileName *cur);
- static void InsertXLogFile( char * fname );
- static bool ReadXLogPage(void);
- static bool RecordIsValid(XLogRecord *record, XLogRecPtr recptr);
- static bool FetchRecord(void);
- static void UpdateCheckPoint(XLogRecord *record);
- static void SelectStartXLog(void);
- static int SearchLastCheckpoint(void);
- static int OpenXLogFile(XLogFileName *sf);
- static void CleanUpList(XLogFileName *list);

  int
  main(int argc, char *argv[])
  {
      int            c;
      bool        force = false;
-     bool        restore = false;
      bool        noupdate = false;
      TransactionId set_xid = 0;
      Oid            set_oid = 0;
--- 53,75 ----
  static ControlFileData ControlFile;        /* pg_control values */
  static uint32 newXlogId,
              newXlogSeg;            /* ID/Segment of new XLOG segment */
+ static bool guessed = false;    /* T if we had to guess at any values */
  static const char *progname;

  static bool ReadControlFile(void);
! static void GuessControlValues(void);
! static void PrintControlValues(bool guessed);
  static void RewriteControlFile(void);
  static void KillExistingXLOG(void);
  static void WriteEmptyXLOG(void);
  static void usage(void);


  int
  main(int argc, char *argv[])
  {
      int            c;
      bool        force = false;
      bool        noupdate = false;
      TransactionId set_xid = 0;
      Oid            set_oid = 0;
***************
*** 142,150 ****
      char       *DataDir;
      int            fd;
      char        path[MAXPGPATH];
!     bool        ctlcorrupted = false;
!     bool        PidLocked = false;
!
      set_pglocale_pgservice(argv[0], "pg_resetxlog");

      progname = get_progname(argv[0]);
--- 84,90 ----
      char       *DataDir;
      int            fd;
      char        path[MAXPGPATH];
!
      set_pglocale_pgservice(argv[0], "pg_resetxlog");

      progname = get_progname(argv[0]);
***************
*** 164,181 ****
      }


!     while ((c = getopt(argc, argv, "fl:m:no:O:x:r")) != -1)
      {
          switch (c)
          {
              case 'f':
                  force = true;
                  break;
!
!             case 'r':
!                 restore = true;
!                 break;
!
              case 'n':
                  noupdate = true;
                  break;
--- 104,117 ----
      }


!     while ((c = getopt(argc, argv, "fl:m:no:O:x:")) != -1)
      {
          switch (c)
          {
              case 'f':
                  force = true;
                  break;
!
              case 'n':
                  noupdate = true;
                  break;
***************
*** 319,335 ****
      }
      else
      {
!         PidLocked = true;
      }

      /*
       * Attempt to read the existing pg_control file
       */
      if (!ReadControlFile())
!     {
!         /* The control file has been corruptted.*/
!         ctlcorrupted = true;
!     }

      /*
       * Adjust fields if required by switches.  (Do this now so that printout,
--- 255,271 ----
      }
      else
      {
!         fprintf(stderr, _("%s: lock file \"%s\" exists\n"
!                           "Is a server running?  If not, delete the lock file and try again.\n"),
!                 progname, path);
!         exit(1);
      }

      /*
       * Attempt to read the existing pg_control file
       */
      if (!ReadControlFile())
!         GuessControlValues();

      /*
       * Adjust fields if required by switches.  (Do this now so that printout,
***************
*** 358,438 ****
          ControlFile.logSeg = minXlogSeg;
      }

-     /* retore the broken control file from WAL file.*/
-     if (restore)
-     {
-
-         /* If the control fine is fine, don't touch it.*/
-         if ( !ctlcorrupted )
-         {
-             printf(_("\nThe control file seems fine, not need to restore it.\n"));
-             printf(_("If you want to restore it anyway, use -f option, but this also will reset the log file.\n"));
-             exit(0);
-         }
-
-
-         /* Try to restore control values from old xlog file, or complain it.*/
-         if (RestoreControlValues(WAL))
-         {
-             /* Success in restoring the checkpoint information from old xlog file.*/
-
-             /* Print it out.*/
-             PrintControlValues();
-
-             /* In case the postmaster is crashed.
-              * But it may be dangerous for the living one.
-              * It may need a more good way.
-              */
-             if (PidLocked)
-             {
-                 ControlFile.state = DB_IN_PRODUCTION;
-             }
-             /* Write the new control file. */
-             RewriteControlFile();
-             printf(_("\nThe control file had been restored.\n"));
-         }
-         else
-         {
-             /* Fail in restoring the checkpoint information from old xlog file. */
-             printf(_("\nCan not restore the control file from XLog file..\n"));
-             printf(_("\nIf you want to restore it anyway, use -f option to guess the information, but this also will
resetthe log file.\n")); 
-         }
-
-         exit(0);
-
-     }
-     if (PidLocked)
-     {
-         fprintf(stderr, _("%s: lock file \"%s\" exists\n"
-                           "Is a server running?  If not, delete the lock file and try again.\n"),
-                 progname, path);
-         exit(1);
-
-     }
      /*
!     * Print out the values in control file if -n is given. if the control file is
!     * corrupted, then inform user to restore it first.
       */
!     if (noupdate)
      {
!         if (!ctlcorrupted)
          {
!             /* The control file is fine, print the values out.*/
!             PrintControlValues();
!             exit(0);
!         }
!         else{
!             /* The control file is corrupted.*/
!             printf(_("The control file had been corrupted.\n"));
!             printf(_("Please use -r option to restore it first.\n"));
              exit(1);
!             }
      }

      /*
       * Don't reset from a dirty pg_control without -f, either.
       */
!     if (ControlFile.state != DB_SHUTDOWNED && !force && !ctlcorrupted)
      {
          printf(_("The database server was not shut down cleanly.\n"
                   "Resetting the transaction log may cause data to be lost.\n"
--- 294,319 ----
          ControlFile.logSeg = minXlogSeg;
      }

      /*
!      * If we had to guess anything, and -f was not given, just print the
!      * guessed values and exit.  Also print if -n is given.
       */
!     if ((guessed && !force) || noupdate)
      {
!         PrintControlValues(guessed);
!         if (!noupdate)
          {
!             printf(_("\nIf these values seem acceptable, use -f to force reset.\n"));
              exit(1);
!         }
!         else
!             exit(0);
      }

      /*
       * Don't reset from a dirty pg_control without -f, either.
       */
!     if (ControlFile.state != DB_SHUTDOWNED && !force)
      {
          printf(_("The database server was not shut down cleanly.\n"
                   "Resetting the transaction log may cause data to be lost.\n"
***************
*** 440,474 ****
          exit(1);
      }

! /*
!      * Try to reset the xlog file.
       */
-
-     /* If the control file is corrupted, and -f option is given, resotre it first.*/
-     if ( ctlcorrupted )
-     {
-         if (force)
-         {
-             if (!RestoreControlValues(WAL))
-             {
-                 printf(_("fails to recover the control file from old xlog files, so we had to guess it.\n"));
-                 RestoreControlValues(GUESS);
-             }
-             printf(_("Restored the control file from old xlog files.\n"));
-         }
-         else
-         {
-             printf(_("Control file corrupted.\nIf you want to proceed anyway, use -f to force reset.\n"));
-             exit(1);
-             }
-     }
-
-     /* Reset the xlog fille.*/
-     UpdateCtlFile4Reset();
      RewriteControlFile();
      KillExistingXLOG();
      WriteEmptyXLOG();
!     printf(_("Transaction log reset\n"));
      return 0;
  }

--- 321,334 ----
          exit(1);
      }

!     /*
!      * Else, do the dirty deed.
       */
      RewriteControlFile();
      KillExistingXLOG();
      WriteEmptyXLOG();
!
!     printf(_("Transaction log reset\n"));
      return 0;
  }

***************
*** 537,542 ****
--- 397,403 ----
                  progname);
          /* We will use the data anyway, but treat it as guessed. */
          memcpy(&ControlFile, buffer, sizeof(ControlFile));
+         guessed = true;
          return true;
      }

***************
*** 547,631 ****
  }


-
-
  /*
!  *  Restore the pg_control values by scanning old xlog files or by guessing it.
!  *
!  * Input parameter:
!  *    WAL:  Restore the pg_control values by scanning old xlog files.
!  *    GUESS: Restore the pg_control values by guessing.
!  * Return:
!  *    TRUE: success in restoring.
!  *    FALSE: fail to restore the values.
!  *
   */
! static bool
! RestoreControlValues(int mode)
  {
      struct timeval tv;
      char       *localeptr;
-     bool    successed = true;

      /*
       * Set up a completely default set of pg_control values.
       */
      memset(&ControlFile, 0, sizeof(ControlFile));

      ControlFile.pg_control_version = PG_CONTROL_VERSION;
      ControlFile.catalog_version_no = CATALOG_VERSION_NO;

!     /*
!      * update the checkpoint value in control file,by searching
!      * xlog segment file, or just guessing it.
       */
!     if (mode == WAL)
!     {
!         int result = SearchLastCheckpoint();

!         if (result > 0) /* The last checkpoint had been found. */
!         {
!             ControlFile.checkPointCopy = lastcheckpoint;
!             ControlFile.checkPointCopy.ThisTimeLineID = LastXLogFile->tli;
!             ControlFile.checkPoint = lastchkp;
!             ControlFile.prevCheckPoint = prevchkp;
!
!             ControlFile.logId = LastXLogFile->logid;
!             ControlFile.logSeg = LastXLogFile->seg + 1;
!             ControlFile.state = state;
!         }
!         else
!             successed = false;
!
!         /* Clean up the list. */
!         CleanUpList(xlogfilelist);
!     }
!     else    /* GUESS */
!     {
!         ControlFile.checkPointCopy.ThisTimeLineID = 2;
!         ControlFile.checkPointCopy.redo.xlogid = 0;
!         ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogLongPHD;
!         ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
!         ControlFile.checkPointCopy.nextXid = (TransactionId) 514;    /* XXX */
!         ControlFile.checkPointCopy.nextOid = FirstBootstrapObjectId;
!         ControlFile.checkPointCopy.nextMulti = FirstMultiXactId;
!         ControlFile.checkPointCopy.nextMultiOffset = 0;
!         ControlFile.checkPointCopy.time = time(NULL);
!         ControlFile.checkPoint = ControlFile.checkPointCopy.redo;

!         /*
!          * Create a new unique installation identifier, since we can no longer
!          * use any old XLOG records.  See notes in xlog.c about the algorithm.
!          */
!         gettimeofday(&tv, NULL);
!         sysidentifier = ((uint64) tv.tv_sec) << 32;
!         sysidentifier |= (uint32) (tv.tv_sec | tv.tv_usec);
!         ControlFile.state = DB_SHUTDOWNED;
!
!     }

      ControlFile.time = time(NULL);
!     ControlFile.system_identifier = sysidentifier;
      ControlFile.maxAlign = MAXIMUM_ALIGNOF;
      ControlFile.floatFormat = FLOATFORMAT_VALUE;
      ControlFile.blcksz = BLCKSZ;
--- 408,458 ----
  }


  /*
!  * Guess at pg_control values when we can't read the old ones.
   */
! static void
! GuessControlValues(void)
  {
+     uint64        sysidentifier;
      struct timeval tv;
      char       *localeptr;

      /*
       * Set up a completely default set of pg_control values.
       */
+     guessed = true;
      memset(&ControlFile, 0, sizeof(ControlFile));

      ControlFile.pg_control_version = PG_CONTROL_VERSION;
      ControlFile.catalog_version_no = CATALOG_VERSION_NO;

!     /*
!      * Create a new unique installation identifier, since we can no longer use
!      * any old XLOG records.  See notes in xlog.c about the algorithm.
       */
!     gettimeofday(&tv, NULL);
!     sysidentifier = ((uint64) tv.tv_sec) << 32;
!     sysidentifier |= (uint32) (tv.tv_sec | tv.tv_usec);

!     ControlFile.system_identifier = sysidentifier;

!     ControlFile.checkPointCopy.redo.xlogid = 0;
!     ControlFile.checkPointCopy.redo.xrecoff = SizeOfXLogLongPHD;
!     ControlFile.checkPointCopy.undo = ControlFile.checkPointCopy.redo;
!     ControlFile.checkPointCopy.ThisTimeLineID = 1;
!     ControlFile.checkPointCopy.nextXid = (TransactionId) 514;    /* XXX */
!     ControlFile.checkPointCopy.nextOid = FirstBootstrapObjectId;
!     ControlFile.checkPointCopy.nextMulti = FirstMultiXactId;
!     ControlFile.checkPointCopy.nextMultiOffset = 0;
!     ControlFile.checkPointCopy.time = time(NULL);

+     ControlFile.state = DB_SHUTDOWNED;
      ControlFile.time = time(NULL);
!     ControlFile.logId = 0;
!     ControlFile.logSeg = 1;
!     ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
!
      ControlFile.maxAlign = MAXIMUM_ALIGNOF;
      ControlFile.floatFormat = FLOATFORMAT_VALUE;
      ControlFile.blcksz = BLCKSZ;
***************
*** 648,654 ****
          exit(1);
      }
      StrNCpy(ControlFile.lc_collate, localeptr, LOCALE_NAME_BUFLEN);
-
      localeptr = setlocale(LC_CTYPE, "");
      if (!localeptr)
      {
--- 475,480 ----
***************
*** 657,678 ****
      }
      StrNCpy(ControlFile.lc_ctype, localeptr, LOCALE_NAME_BUFLEN);

!     return successed;
  }


  /*
!  * Print the out pg_control values.
   *
   * NB: this display should be just those fields that will not be
   * reset by RewriteControlFile().
   */
  static void
! PrintControlValues(void)
  {
      char        sysident_str[32];

!     printf(_("pg_control values:\n\n"));

      /*
       * Format system_identifier separately to keep platform-dependent format
--- 483,510 ----
      }
      StrNCpy(ControlFile.lc_ctype, localeptr, LOCALE_NAME_BUFLEN);

!     /*
!      * XXX eventually, should try to grovel through old XLOG to develop more
!      * accurate values for TimeLineID, nextXID, etc.
!      */
  }


  /*
!  * Print the guessed pg_control values when we had to guess.
   *
   * NB: this display should be just those fields that will not be
   * reset by RewriteControlFile().
   */
  static void
! PrintControlValues(bool guessed)
  {
      char        sysident_str[32];

!     if (guessed)
!         printf(_("Guessed pg_control values:\n\n"));
!     else
!         printf(_("pg_control values:\n\n"));

      /*
       * Format system_identifier separately to keep platform-dependent format
***************
*** 706,717 ****
      printf(_("LC_CTYPE:                             %s\n"), ControlFile.lc_ctype);
  }

  /*
! * Update the control file before reseting it.
! */
! static void
! UpdateCtlFile4Reset(void)
  {
      /*
       * Adjust fields as needed to force an empty XLOG starting at the next
       * available segment.
--- 538,553 ----
      printf(_("LC_CTYPE:                             %s\n"), ControlFile.lc_ctype);
  }

+
  /*
!  * Write out the new pg_control file.
!  */
! static void
! RewriteControlFile(void)
  {
+     int            fd;
+     char        buffer[PG_CONTROL_SIZE]; /* need not be aligned */
+
      /*
       * Adjust fields as needed to force an empty XLOG starting at the next
       * available segment.
***************
*** 742,758 ****
      ControlFile.checkPoint = ControlFile.checkPointCopy.redo;
      ControlFile.prevCheckPoint.xlogid = 0;
      ControlFile.prevCheckPoint.xrecoff = 0;
- }
-
- /*
-  * Write out the new pg_control file.
-  */
- static void
- RewriteControlFile(void)
- {
-     int            fd;
-     char        buffer[PG_CONTROL_SIZE]; /* need not be aligned */
-

      /* Contents are protected with a CRC */
      INIT_CRC32(ControlFile.crc);
--- 578,583 ----
***************
*** 847,852 ****
--- 672,678 ----
          errno = 0;
      }
  #ifdef WIN32
+
      /*
       * This fix is in mingw cvs (runtime/mingwex/dirent.c rev 1.4), but not in
       * released version
***************
*** 975,1638 ****
      printf(_("%s resets the PostgreSQL transaction log.\n\n"), progname);
      printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
      printf(_("Options:\n"));
!     printf(_("  -f              force reset xlog to be done, if the control file is corrupted, then try to restore
it.\n"));
!     printf(_("  -r              restore the pg_control file from old XLog files, resets is not done..\n"));
      printf(_("  -l TLI,FILE,SEG force minimum WAL starting location for new transaction log\n"));
!     printf(_("  -n              show extracted control values of existing pg_control file.\n"));
!     printf(_("  -m multiXID     set next multi transaction ID\n"));
      printf(_("  -o OID          set next OID\n"));
!     printf(_("  -O multiOffset  set next multi transaction offset\n"));
      printf(_("  -x XID          set next transaction ID\n"));
      printf(_("  --help          show this help, then exit\n"));
      printf(_("  --version       output version information, then exit\n"));
      printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
  }
-
-
-
- /*
-  * The following routines are mainly used for getting pg_control values
-  * from the xlog file.
-  */
-
-  /* some local varaibles.*/
- static int              logFd=0; /* kernel FD for current input file */
- static int              logRecOff;      /* offset of next record in page */
- static char             pageBuffer[BLCKSZ];     /* current page */
- static XLogRecPtr       curRecPtr;      /* logical address of current record */
- static XLogRecPtr       prevRecPtr;     /* logical address of previous record */
- static char             *readRecordBuf = NULL; /* ReadRecord result area */
- static uint32           readRecordBufSize = 0;
- static int32            logPageOff;     /* offset of current page in file */
- static uint32           logId;          /* current log file id */
- static uint32           logSeg;         /* current log file segment */
- static uint32           logTli;         /* current log file timeline */
-
- /*
-  * Get existing XLOG files
-  */
- static void
- GetXLogFiles(void)
- {
-     DIR           *xldir;
-     struct dirent *xlde;
-
-     /* Open the xlog direcotry.*/
-     xldir = opendir(XLOGDIR);
-     if (xldir == NULL)
-     {
-         fprintf(stderr, _("%s: could not open directory \"%s\": %s\n"),
-                 progname, XLOGDIR, strerror(errno));
-         exit(1);
-     }
-
-     /* Search the directory, insert the segment files into the xlogfilelist.*/
-     errno = 0;
-     while ((xlde = readdir(xldir)) != NULL)
-     {
-         if (ValidXLogFileName(xlde->d_name)) {
-             /* XLog file is found, insert it into the xlogfilelist.*/
-             InsertXLogFile(xlde->d_name);
-         };
-         errno = 0;
-     }
- #ifdef WIN32
-     if (GetLastError() == ERROR_NO_MORE_FILES)
-         errno = 0;
- #endif
-
-     if (errno)
-     {
-         fprintf(stderr, _("%s: could not read from directory \"%s\": %s\n"),
-                 progname, XLOGDIR, strerror(errno));
-         exit(1);
-     }
-     closedir(xldir);
- }
-
- /*
-  * Insert a file while had been found in the xlog folder into xlogfilelist.
-  * The xlogfile list is matained in a increasing order.
-  *
-  * The input parameter is the name of the xlog  file, the name is assumpted
-  * valid.
-  */
- static void
- InsertXLogFile( char * fname )
- {
-     XLogFileName * NewSegFile, *Curr, *Prev;
-     bool append2end = false;
-
-     /* Allocate a new node for the new file. */
-     NewSegFile = (XLogFileName *) malloc(sizeof(XLogFileName));
-     strcpy(NewSegFile->fname,fname); /* setup the name */
-     /* extract the time line, logid, and segment number from the name.*/
-     sscanf(fname, "%8x%8x%8x", &(NewSegFile->tli), &(NewSegFile->logid), &(NewSegFile->seg));
-     NewSegFile->next = NULL;
-
-     /* Ensure the xlog file is active and valid.*/
-     if (! ValidXLogFileHeader(NewSegFile))
-     {
-         free(NewSegFile);
-         return;
-     }
-
-     /* the list is empty.*/
-     if ( xlogfilelist == NULL ) {
-         xlogfilelist = NewSegFile;
-         return;
-     };
-
-     /* try to search the list and find the insert point. */
-     Prev=Curr=xlogfilelist;
-     while( CmpXLogFileOT(NewSegFile, Curr))
-     {
-         /* the node is appended to the end of the list.*/
-         if (Curr->next == NULL)
-         {
-             append2end = true;
-             break;
-         }
-         Prev=Curr;
-         Curr = Curr->next;
-     }
-
-     /* Insert the new node to the list.*/
-     if ( append2end )
-     {
-         /* We need to append the new node to the end of the list */
-         Curr->next = NewSegFile;
-     }
-     else
-     {
-         NewSegFile->next = Curr;
-         /* prev should not be the list head. */
-         if ( Prev != NULL && Prev != xlogfilelist)
-         {
-             Prev->next = NewSegFile;
-         }
-     }
-     /* Update the list head if it is needed.*/
-     if ((Curr == xlogfilelist) && !append2end)
-     {
-         xlogfilelist = NewSegFile;
-     }
-
- }
-
- /*
-  * compare two xlog file from their name to see which one is latest.
-  *
-  * Return true for file 2 is the lastest file.
-  *
-  */
- static bool
- CmpXLogFileOT(XLogFileName * f1, XLogFileName *f2)
- {
-         if (f2->tli >= f1->tli)
-         {
-                 if (f2->logid >= f1->logid)
-                 {
-                         if (f2->seg > f1->seg) return false;
-                 }
-         }
-         return true;
-
- }
-
- /* check is two segment file is continous.*/
- static bool
- IsNextSeg(XLogFileName *prev, XLogFileName *cur)
- {
-     uint32 logid, logseg;
-
-     if (prev->tli != cur->tli) return false;
-
-     logid = prev->logid;
-     logseg = prev->seg;
-     NextLogSeg(logid, logseg);
-
-     if ((logid == cur->logid) && (logseg == cur->seg)) return true;
-
-     return false;
-
- }
-
-
- /*
- * Select the oldest xlog file in the latest time line.
- */
- static void
- SelectStartXLog( void )
- {
-     XLogFileName *tmp;
-     CurXLogFile = xlogfilelist;
-
-     if (xlogfilelist == NULL)
-     {
-         return;
-     }
-
-     tmp=LastXLogFile=CurXLogFile=xlogfilelist;
-
-     while(tmp->next != NULL)
-     {
-
-         /*
-          * we should ensure that from the first to
-          * the last segment file is continous.
-          * */
-         if (!IsNextSeg(tmp, tmp->next))
-         {
-             CurXLogFile = tmp->next;
-         }
-         tmp=tmp->next;
-     }
-
-     LastXLogFile = tmp;
-
- }
-
- /*
-  * Check if the file is a valid xlog file.
-  *
-  * Return true for the input file is a valid xlog file.
-  *
-  * The input parameter is the name of the xlog file.
-  *
-  */
- static bool
- ValidXLogFileName(char * fname)
- {
-     uint32 logTLI, logId, logSeg;
-     if (strlen(fname) != 24 ||
-         strspn(fname, "0123456789ABCDEF") != 24 ||
-         sscanf(fname, "%8x%8x%8x", &logTLI, &logId, &logSeg) != 3)
-         return false;
-     return true;
-
- }
-
- /* Ensure the xlog file is active and valid.*/
- static bool
- ValidXLogFileHeader(XLogFileName *segfile)
- {
-     int fd;
-     char buffer[BLCKSZ];
-     char        path[MAXPGPATH];
-     size_t nread;
-
-     snprintf(path, MAXPGPATH, "%s/%s", XLOGDIR, segfile->fname);
-     fd = open(path, O_RDONLY | PG_BINARY, 0);
-         if (fd < 0)
-     {
-         return false;
-     }
-     nread = read(fd, buffer, BLCKSZ);
-     if (nread == BLCKSZ)
-     {
-         XLogPageHeader hdr = (XLogPageHeader)buffer;
-
-         if (ValidXLOGPageHeader(hdr, segfile->tli, segfile->logid, segfile->seg))
-         {
-             return true;
-         }
-
-     }
-     return false;
-
- }
- static bool
- ValidXLOGPageHeader(XLogPageHeader hdr, uint32 tli, uint32 id, uint32 seg)
- {
-     XLogRecPtr    recaddr;
-
-     if (hdr->xlp_magic != XLOG_PAGE_MAGIC)
-     {
-         return false;
-     }
-     if ((hdr->xlp_info & ~XLP_ALL_FLAGS) != 0)
-     {
-         return false;
-     }
-     if (hdr->xlp_info & XLP_LONG_HEADER)
-     {
-         XLogLongPageHeader longhdr = (XLogLongPageHeader) hdr;
-
-         if (longhdr->xlp_seg_size != XLogSegSize)
-         {
-             return false;
-         }
-         /* Get the system identifier from the segment file header.*/
-         sysidentifier = ((XLogLongPageHeader) pageBuffer)->xlp_sysid;
-     }
-
-     recaddr.xlogid = id;
-     recaddr.xrecoff = seg * XLogSegSize + logPageOff;
-     if (!XLByteEQ(hdr->xlp_pageaddr, recaddr))
-     {
-         return false;
-     }
-
-     if (hdr->xlp_tli != tli)
-     {
-         return false;
-     }
-     return true;
- }
-
-
- /* Read another page, if possible */
- static bool
- ReadXLogPage(void)
- {
-     size_t nread;
-
-     /* Need to advance to the new segment file.*/
-     if ( logPageOff >= XLogSegSize )
-     {
-         close(logFd);
-         logFd = 0;
-     }
-
-     /* Need to open the segement file.*/
-     if ((logFd <= 0) && (CurXLogFile != NULL))
-     {
-         if (OpenXLogFile(CurXLogFile) < 0)
-         {
-             return false;
-         }
-         CurXLogFile = CurXLogFile->next;
-     }
-
-     /* Read a page from the openning segement file.*/
-     nread = read(logFd, pageBuffer, BLCKSZ);
-
-     if (nread == BLCKSZ)
-     {
-         logPageOff += BLCKSZ;
-         if (ValidXLOGPageHeader( (XLogPageHeader)pageBuffer, logTli, logId, logSeg))
-             return true;
-     }
-
-     return false;
- }
-
- /*
-  * CRC-check an XLOG record.  We do not believe the contents of an XLOG
-  * record (other than to the minimal extent of computing the amount of
-  * data to read in) until we've checked the CRCs.
-  *
-  * We assume all of the record has been read into memory at *record.
-  */
- static bool
- RecordIsValid(XLogRecord *record, XLogRecPtr recptr)
- {
-     pg_crc32    crc;
-     int            i;
-     uint32        len = record->xl_len;
-     BkpBlock    bkpb;
-     char       *blk;
-
-     /* First the rmgr data */
-     INIT_CRC32(crc);
-     COMP_CRC32(crc, XLogRecGetData(record), len);
-
-     /* Add in the backup blocks, if any */
-     blk = (char *) XLogRecGetData(record) + len;
-     for (i = 0; i < XLR_MAX_BKP_BLOCKS; i++)
-     {
-         uint32    blen;
-
-         if (!(record->xl_info & XLR_SET_BKP_BLOCK(i)))
-             continue;
-
-         memcpy(&bkpb, blk, sizeof(BkpBlock));
-         if (bkpb.hole_offset + bkpb.hole_length > BLCKSZ)
-         {
-             return false;
-         }
-         blen = sizeof(BkpBlock) + BLCKSZ - bkpb.hole_length;
-         COMP_CRC32(crc, blk, blen);
-         blk += blen;
-     }
-
-     /* Check that xl_tot_len agrees with our calculation */
-     if (blk != (char *) record + record->xl_tot_len)
-     {
-         return false;
-     }
-
-     /* Finally include the record header */
-     COMP_CRC32(crc, (char *) record + sizeof(pg_crc32),
-                SizeOfXLogRecord - sizeof(pg_crc32));
-     FIN_CRC32(crc);
-
-     if (!EQ_CRC32(record->xl_crc, crc))
-     {
-         return false;
-     }
-
-     return true;
- }
-
-
-
- /*
-  * Attempt to read an XLOG record into readRecordBuf.
-  */
- static bool
- FetchRecord(void)
- {
-     char       *buffer;
-     XLogRecord *record;
-     XLogContRecord *contrecord;
-     uint32        len, total_len;
-
-
-     while (logRecOff <= 0 || logRecOff > BLCKSZ - SizeOfXLogRecord)
-     {
-         /* Need to advance to new page */
-         if (! ReadXLogPage())
-         {
-             return false;
-         }
-
-         logRecOff = XLogPageHeaderSize((XLogPageHeader) pageBuffer);
-         if ((((XLogPageHeader) pageBuffer)->xlp_info & ~XLP_LONG_HEADER) != 0)
-         {
-             /* Check for a continuation record */
-             if (((XLogPageHeader) pageBuffer)->xlp_info & XLP_FIRST_IS_CONTRECORD)
-             {
-                 contrecord = (XLogContRecord *) (pageBuffer + logRecOff);
-                 logRecOff += MAXALIGN(contrecord->xl_rem_len + SizeOfXLogContRecord);
-             }
-         }
-     }
-
-     curRecPtr.xlogid = logId;
-     curRecPtr.xrecoff = logSeg * XLogSegSize + logPageOff + logRecOff;
-     record = (XLogRecord *) (pageBuffer + logRecOff);
-
-     if (record->xl_len == 0)
-     {
-         return false;
-     }
-
-     total_len = record->xl_tot_len;
-
-     /*
-      * Allocate or enlarge readRecordBuf as needed.  To avoid useless
-      * small increases, round its size to a multiple of BLCKSZ, and make
-      * sure it's at least 4*BLCKSZ to start with.  (That is enough for all
-      * "normal" records, but very large commit or abort records might need
-      * more space.)
-      */
-     if (total_len > readRecordBufSize)
-     {
-         uint32        newSize = total_len;
-
-         newSize += BLCKSZ - (newSize % BLCKSZ);
-         newSize = Max(newSize, 4 * BLCKSZ);
-         if (readRecordBuf)
-             free(readRecordBuf);
-         readRecordBuf = (char *) malloc(newSize);
-         if (!readRecordBuf)
-         {
-             readRecordBufSize = 0;
-             return false;
-         }
-         readRecordBufSize = newSize;
-     }
-
-     buffer = readRecordBuf;
-     len = BLCKSZ - curRecPtr.xrecoff % BLCKSZ; /* available in block */
-     if (total_len > len)
-     {
-         /* Need to reassemble record */
-         uint32            gotlen = len;
-
-         memcpy(buffer, record, len);
-         record = (XLogRecord *) buffer;
-         buffer += len;
-         for (;;)
-         {
-             uint32    pageHeaderSize;
-
-             if (!ReadXLogPage())
-             {
-                 return false;
-             }
-             if (!(((XLogPageHeader) pageBuffer)->xlp_info & XLP_FIRST_IS_CONTRECORD))
-             {
-                 return false;
-             }
-             pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) pageBuffer);
-             contrecord = (XLogContRecord *) (pageBuffer + pageHeaderSize);
-             if (contrecord->xl_rem_len == 0 ||
-                 total_len != (contrecord->xl_rem_len + gotlen))
-             {
-                 return false;
-             }
-             len = BLCKSZ - pageHeaderSize - SizeOfXLogContRecord;
-             if (contrecord->xl_rem_len > len)
-             {
-                 memcpy(buffer, (char *)contrecord + SizeOfXLogContRecord, len);
-                 gotlen += len;
-                 buffer += len;
-                 continue;
-             }
-             memcpy(buffer, (char *) contrecord + SizeOfXLogContRecord,
-                    contrecord->xl_rem_len);
-             logRecOff = MAXALIGN(pageHeaderSize + SizeOfXLogContRecord + contrecord->xl_rem_len);
-             break;
-         }
-         if (!RecordIsValid(record, curRecPtr))
-         {
-             return false;
-         }
-         return true;
-     }
-     /* Record is contained in this page */
-     memcpy(buffer, record, total_len);
-     record = (XLogRecord *) buffer;
-     logRecOff += MAXALIGN(total_len);
-     if (!RecordIsValid(record, curRecPtr))
-     {
-
-         return false;
-     }
-     return true;
- }
-
- /*
-  * if the record is checkpoint, update the lastest checkpoint record.
-  */
- static void
- UpdateCheckPoint(XLogRecord *record)
- {
-     uint8    info = record->xl_info & ~XLR_INFO_MASK;
-
-     if ((info == XLOG_CHECKPOINT_SHUTDOWN) ||
-         (info == XLOG_CHECKPOINT_ONLINE))
-     {
-          CheckPoint *chkpoint = (CheckPoint*) XLogRecGetData(record);
-          prevchkp = lastchkp;
-          lastchkp = curRecPtr;
-          lastcheckpoint = *chkpoint;
-
-          /* update the database state.*/
-          switch(info)
-          {
-             case XLOG_CHECKPOINT_SHUTDOWN:
-                 state = DB_SHUTDOWNED;
-                 break;
-             case XLOG_CHECKPOINT_ONLINE:
-                 state = DB_IN_PRODUCTION;
-                 break;
-          }
-          found_checkpoint ++ ;
-     }
- }
-
- static int
- OpenXLogFile(XLogFileName *sf)
- {
-
-     char        path[MAXPGPATH];
-
-     if ( logFd > 0 ) close(logFd);
-
-     /* Open a  Xlog segment file. */
-     snprintf(path, MAXPGPATH, "%s/%s", XLOGDIR, sf->fname);
-     logFd = open(path, O_RDONLY | PG_BINARY, 0);
-
-     if (logFd < 0)
-     {
-         fprintf(stderr, _("%s: Can not open xlog file %s.\n"), progname,path);
-         return -1;
-     }
-
-     /* Setup the parameter for searching. */
-     logPageOff = -BLCKSZ;        /* so 1st increment in readXLogPage gives 0 */
-     logRecOff = 0;
-     logId = sf->logid;
-     logSeg = sf->seg;
-     logTli = sf->tli;
-     return logFd;
- }
-
- /*
-  * Search the lastest checkpoint in the lastest XLog segment file.
-  *
-  * The return value is the total checkpoints which had been found
-  * in the XLog segment file.
-  */
- static int
- SearchLastCheckpoint(void)
- {
-
-     /* retrive all of the active xlog files from xlog direcotry
-      * into a list by increasing order, according their timeline,
-      * log id, segment id.
-     */
-     GetXLogFiles();
-
-     /* Select the oldest segment file in the lastest time line.*/
-     SelectStartXLog();
-
-     /* No segment file was found.*/
-     if ( CurXLogFile == NULL )
-     {
-         return 0;
-     }
-
-     /* initial it . */
-     logFd=logId=logSeg=logTli=0;
-
-     /*
-      * Search the XLog segment file from beginning to end,
-      * if checkpoint record is found, then update the
-      * latest check point.
-      */
-     while (FetchRecord())
-     {
-         /* To see if the record is checkpoint record. */
-         if (((XLogRecord *) readRecordBuf)->xl_rmid == RM_XLOG_ID)
-             UpdateCheckPoint((XLogRecord *) readRecordBuf);
-         prevRecPtr = curRecPtr;
-     }
-
-     /* We can not know clearly if we had reached the end.
-      * But just check if we reach the last segment file,
-      * if it is not, then some problem there.
-      * (We need a better way to know the abnormal broken during the search)
-      */
-     if ((logId != LastXLogFile->logid) && (logSeg != LastXLogFile->seg))
-     {
-         return 0;
-     }
-
-     /*
-      * return the checkpoints which had been found yet,
-      * let others know how much checkpointes are found.
-      */
-     return found_checkpoint;
- }
-
- /* Clean up the allocated list.*/
- static void
- CleanUpList(XLogFileName *list)
- {
-
-     XLogFileName *tmp;
-     tmp = list;
-     while(list != NULL)
-     {
-         tmp=list->next;
-         free(list);
-         list=tmp;
-     }
-
- }
-
--- 801,814 ----
      printf(_("%s resets the PostgreSQL transaction log.\n\n"), progname);
      printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
      printf(_("Options:\n"));
!     printf(_("  -f              force update to be done\n"));
      printf(_("  -l TLI,FILE,SEG force minimum WAL starting location for new transaction log\n"));
!     printf(_("  -m XID          set next multitransaction ID\n"));
!     printf(_("  -n              no update, just show extracted control values (for testing)\n"));
      printf(_("  -o OID          set next OID\n"));
!     printf(_("  -O OFFSET       set next multitransaction offset\n"));
      printf(_("  -x XID          set next transaction ID\n"));
      printf(_("  --help          show this help, then exit\n"));
      printf(_("  --version       output version information, then exit\n"));
      printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
  }