/* By default pages are 1024 bytes in size. */
#define BT_DEFAULT_PGSZ 1024

/* By default blocks are 512K bytes in size. */
#define BT_DEFAULT_BLKSZ (512*1024)

/*


**
** pgsz, blksz:
**   Byte offset 0 of the database file is the first byte of both page 1
**   and block 1. Each page is pHdr->pgsz bytes in size. Each block is
**   pHdr->blksz bytes in size. It is guaranteed that the block-size is
**   an integer multiple of the page-size.
**
................................................................................
**   sub-tree, not including any overflow pages. Pages (except overflow 
**   pages) are always allocated contiguously within the block.
**
**   The reason these are likely a stop-gap is that the write-magnification
**   caused by using a b-tree for to populate level-0 sub-trees is too 
**   expensive.
*/

struct BtDbHdr {

  u32 pgsz;                       /* Page size in bytes */
  u32 blksz;                      /* Block size in bytes */
  u32 nPg;                        /* Size of database file in pages */

  u32 iRoot;                      /* B-tree root page */
  u32 iMRoot;                     /* Root page of meta-tree */
  u32 iSRoot;                     /* Root page of schedule-tree */

/* By default pages are 1024 bytes in size. */
#define BT_DEFAULT_PGSZ 1024

/* By default blocks are 512K bytes in size. */
#define BT_DEFAULT_BLKSZ (512*1024)

/*
** This structure is the in-memory representation of all data stored in
** the database header at the start of the db file.
**
** pgsz, blksz:
**   Byte offset 0 of the database file is the first byte of both page 1
**   and block 1. Each page is pHdr->pgsz bytes in size. Each block is
**   pHdr->blksz bytes in size. It is guaranteed that the block-size is
**   an integer multiple of the page-size.
**
................................................................................
**   sub-tree, not including any overflow pages. Pages (except overflow 
**   pages) are always allocated contiguously within the block.
**
**   The reason these are likely a stop-gap is that the write-magnification
**   caused by using a b-tree for to populate level-0 sub-trees is too 
**   expensive.
*/
#define BT_DBHDR_STRING "SQLite4 bt database 0001"
struct BtDbHdr {
  char azStr[24];                 /* Copy of BT_DBHDR_STRING */
  u32 pgsz;                       /* Page size in bytes */
  u32 blksz;                      /* Block size in bytes */
  u32 nPg;                        /* Size of database file in pages */

  u32 iRoot;                      /* B-tree root page */
  u32 iMRoot;                     /* Root page of meta-tree */
  u32 iSRoot;                     /* Root page of schedule-tree */

    }
  }

  aLog[5] = iLast;
  return btLogHashRollback(pLog, btLogFrameHash(pLog, iLast), iLast);
}

static void btLogDecodeDbhdr(BtLog *pLog, u8 *aData, BtDbHdr *pHdr){
  BtDbHdrCksum hdr;
  u32 aCksum[2] = {0,0};

  if( aData ){
    memcpy(&hdr, aData, sizeof(BtDbHdrCksum));
    btLogChecksum32(1, (u8*)&hdr, offsetof(BtDbHdrCksum, aCksum), 0, aCksum);
  }

  if( aData==0 || aCksum[0]!=hdr.aCksum[0] || aCksum[1]!=hdr.aCksum[1] ){
    memset(&hdr, 0, sizeof(BtDbHdrCksum));
    hdr.hdr.pgsz = pLog->pLock->nPgsz;
    hdr.hdr.blksz = pLog->pLock->nBlksz;
    hdr.hdr.nPg = 2;
    hdr.hdr.iRoot = 2;
  }

  memcpy(pHdr, &hdr, sizeof(BtDbHdr));












}

static int btLogReadDbhdr(BtLog *pLog, BtDbHdr *pHdr, u32 iFrame){
  BtLock *p = pLog->pLock;        /* BtLock handle */
  int rc;                         /* Return code */
  i64 nByte;                      /* Size of database file in byte */
  u8 *aBuffer[sizeof(BtDbHdrCksum)];
  u8 *aData = 0;

  if( iFrame==0 ){
    rc = p->pVfs->xSize(p->pFd, &nByte);
    if( rc==SQLITE4_OK && nByte>0 ){
      rc = p->pVfs->xRead(p->pFd, 0, aBuffer, sizeof(BtDbHdrCksum));
      aData = aBuffer;
................................................................................
    i64 iOff = btLogFrameOffset(pLog, pLog->snapshot.dbhdr.pgsz, iFrame);
    iOff += sizeof(BtFrameHdr);
    rc = p->pVfs->xRead(pLog->pFd, iOff, aBuffer, sizeof(BtDbHdrCksum));
    aData = aBuffer;
  }

  if( rc==SQLITE4_OK ){
    btLogDecodeDbhdr(pLog, aData, pHdr);
  }
  return rc;
}

static int btLogUpdateDbhdr(BtLog *pLog, u8 *aData){
  BtDbHdrCksum hdr;

................................................................................
      pShm->ckpt.iFirstRead = pHdr->iFirstFrame;
      pShm->ckpt.iFirstRecover = pHdr->iFirstFrame;
      rc = btLogRollbackRecovery(pLog, &ctx);
      pLog->snapshot.iNextFrame = ctx.iNextFrame;
      pLog->snapshot.dbhdr.pgsz = pHdr->nPgsz;
      assert( pShm->ckpt.iFirstRead>0 );
    }


    /* Based on the wal-header, the page-size and number of pages in the
    ** database are now known and stored in snapshot.dbhdr. But the other
    ** header field values (iCookie, iRoot etc.) are still unknown. Read
    ** them from page 1 of the database file now.  */

    rc = btLogReadDbhdr(pLog, &pLog->snapshot.dbhdr, ctx.iPageOneFrame);


  }else if( rc==SQLITE4_OK ){
    /* There is no data in the log file. Read the database header directly
    ** from offset 0 of the database file.  */
    btLogZeroSnapshot(pLog);
    rc = btLogReadDbhdr(pLog, &pLog->snapshot.dbhdr, 0);
  }
















  if( rc==SQLITE4_OK ){
    btDebugTopology(
        pLog->pLock, "recovered", pLog->snapshot.iHashSide, pLog->snapshot.aLog
    );

    btDebugDbhdr(pLog->pLock, "read", &pLog->snapshot.dbhdr);
................................................................................
    if( rc==SQLITE4_OK ){
      rc = btLogUpdateSharedHdr(pLog);
    }
  }

 open_out:
  if( rc!=SQLITE4_OK ){
    sqlite4_free(pEnv, pLog);
    pLog = 0;
  }
  *ppLog = pLog;
  return rc;
}

/*
................................................................................
*/
int sqlite4BtLogClose(BtLog *pLog, int bCleanup){
  int rc = SQLITE4_OK;
  if( pLog ){
    sqlite4_env *pEnv = pLog->pLock->pEnv;
    bt_env *pVfs = pLog->pLock->pVfs;

    pVfs->xClose(pLog->pFd);
    if( bCleanup ){
      BtPager *pPager = (BtPager*)pLog->pLock;
      const char *zWal = sqlite4BtPagerFilename(pPager, BT_PAGERFILE_LOG);
      rc = pVfs->xUnlink(pEnv, pVfs, zWal);
    }

    sqlite4_free(pEnv, pLog->apShm);
................................................................................
}

static int btLogMerge(BtLog *pLog, u8 *aBuf){
  bt_db *db = (bt_db*)sqlite4BtPagerExtra((BtPager*)pLog->pLock);
  return sqlite4BtMerge(db, &pLog->snapshot.dbhdr, aBuf);
}


int sqlite4BtLogCheckpoint(BtLog *pLog, int nFrameBuffer){
  BtLock *pLock = pLog->pLock;
  int rc;

  /* Take the CHECKPOINTER lock. */
  rc = sqlite4BtLockCkpt(pLock);
  if( rc==SQLITE4_OK ){
................................................................................
    pLog->snapshot.dbhdr.iCookie = iCookie;
    btLogUpdateDbhdr(pLog, sqlite4BtPageData(pOne));
  }
  sqlite4BtPageRelease(pOne);

  return rc;
}

    }
  }

  aLog[5] = iLast;
  return btLogHashRollback(pLog, btLogFrameHash(pLog, iLast), iLast);
}

static int btLogDecodeDbhdr(BtLog *pLog, u8 *aData, BtDbHdr *pHdr){
  BtDbHdrCksum hdr;
  u32 aCksum[2] = {0,0};

  if( aData ){
    memcpy(&hdr, aData, sizeof(BtDbHdrCksum));
    btLogChecksum32(1, (u8*)&hdr, offsetof(BtDbHdrCksum, aCksum), 0, aCksum);
  }

  if( aData==0 || aCksum[0]!=hdr.aCksum[0] || aCksum[1]!=hdr.aCksum[1] ){
    return SQLITE4_NOTFOUND;




  }

  memcpy(pHdr, &hdr, sizeof(BtDbHdr));
  return SQLITE4_OK;
}

static void btLogZeroDbhdr(BtLog *pLog, BtDbHdr *pHdr){
  assert( sizeof(pHdr->azStr)==strlen(BT_DBHDR_STRING) );

  memset(pHdr, 0, sizeof(BtDbHdr));
  memcpy(pHdr->azStr, BT_DBHDR_STRING, strlen(BT_DBHDR_STRING));
  pHdr->pgsz = pLog->pLock->nPgsz;
  pHdr->blksz = pLog->pLock->nBlksz;
  pHdr->nPg = 2;
  pHdr->iRoot = 2;
}

static int btLogReadDbhdr(BtLog *pLog, BtDbHdr *pHdr, u32 iFrame){
  BtLock *p = pLog->pLock;        /* BtLock handle */
  int rc;                         /* Return code */
  i64 nByte;                      /* Size of database file in byte */
  u8 aBuffer[sizeof(BtDbHdrCksum)];
  u8 *aData = 0;

  if( iFrame==0 ){
    rc = p->pVfs->xSize(p->pFd, &nByte);
    if( rc==SQLITE4_OK && nByte>0 ){
      rc = p->pVfs->xRead(p->pFd, 0, aBuffer, sizeof(BtDbHdrCksum));
      aData = aBuffer;
................................................................................
    i64 iOff = btLogFrameOffset(pLog, pLog->snapshot.dbhdr.pgsz, iFrame);
    iOff += sizeof(BtFrameHdr);
    rc = p->pVfs->xRead(pLog->pFd, iOff, aBuffer, sizeof(BtDbHdrCksum));
    aData = aBuffer;
  }

  if( rc==SQLITE4_OK ){
    rc = btLogDecodeDbhdr(pLog, aData, pHdr);
  }
  return rc;
}

static int btLogUpdateDbhdr(BtLog *pLog, u8 *aData){
  BtDbHdrCksum hdr;

................................................................................
      pShm->ckpt.iFirstRead = pHdr->iFirstFrame;
      pShm->ckpt.iFirstRecover = pHdr->iFirstFrame;
      rc = btLogRollbackRecovery(pLog, &ctx);
      pLog->snapshot.iNextFrame = ctx.iNextFrame;
      pLog->snapshot.dbhdr.pgsz = pHdr->nPgsz;
      assert( pShm->ckpt.iFirstRead>0 );
    }
    assert( rc!=SQLITE4_NOTFOUND );

    /* Based on the wal-header, the page-size and number of pages in the
    ** database are now known and stored in snapshot.dbhdr. But the other
    ** header field values (iCookie, iRoot etc.) are still unknown. Read
    ** them from page 1 of the database file now.  */
    if( rc==SQLITE4_OK ){
      rc = btLogReadDbhdr(pLog, &pLog->snapshot.dbhdr, ctx.iPageOneFrame);
    }

  }else if( rc==SQLITE4_OK ){
    /* There is no data in the log file. Read the database header directly
    ** from offset 0 of the database file.  */
    btLogZeroSnapshot(pLog);
    rc = btLogReadDbhdr(pLog, &pLog->snapshot.dbhdr, 0);
  }

  if( rc==SQLITE4_NOTFOUND ){
    /* Check the size of the db file. If it is greater than zero bytes in
    ** size, refuse to open the file (as it is probably not a database
    ** file). Or, if it is exactly zero bytes in size, this is a brand
    ** new database.  */
    rc = pVfs->xSize(pLog->pLock->pFd, &nByte);
    if( rc==SQLITE4_OK ){
      if( nByte==0 ){
        btLogZeroDbhdr(pLog, &pLog->snapshot.dbhdr);
      }else{
        rc = btErrorBkpt(SQLITE4_NOTADB);
      }
    }
  }

  if( rc==SQLITE4_OK ){
    btDebugTopology(
        pLog->pLock, "recovered", pLog->snapshot.iHashSide, pLog->snapshot.aLog
    );

    btDebugDbhdr(pLog->pLock, "read", &pLog->snapshot.dbhdr);
................................................................................
    if( rc==SQLITE4_OK ){
      rc = btLogUpdateSharedHdr(pLog);
    }
  }

 open_out:
  if( rc!=SQLITE4_OK ){
    sqlite4BtLogClose(pLog, 0);
    pLog = 0;
  }
  *ppLog = pLog;
  return rc;
}

/*
................................................................................
*/
int sqlite4BtLogClose(BtLog *pLog, int bCleanup){
  int rc = SQLITE4_OK;
  if( pLog ){
    sqlite4_env *pEnv = pLog->pLock->pEnv;
    bt_env *pVfs = pLog->pLock->pVfs;

    if( pLog->pFd ) pVfs->xClose(pLog->pFd);
    if( bCleanup ){
      BtPager *pPager = (BtPager*)pLog->pLock;
      const char *zWal = sqlite4BtPagerFilename(pPager, BT_PAGERFILE_LOG);
      rc = pVfs->xUnlink(pEnv, pVfs, zWal);
    }

    sqlite4_free(pEnv, pLog->apShm);
................................................................................
}

static int btLogMerge(BtLog *pLog, u8 *aBuf){
  bt_db *db = (bt_db*)sqlite4BtPagerExtra((BtPager*)pLog->pLock);
  return sqlite4BtMerge(db, &pLog->snapshot.dbhdr, aBuf);
}


int sqlite4BtLogCheckpoint(BtLog *pLog, int nFrameBuffer){
  BtLock *pLock = pLog->pLock;
  int rc;

  /* Take the CHECKPOINTER lock. */
  rc = sqlite4BtLockCkpt(pLock);
  if( rc==SQLITE4_OK ){
................................................................................
    pLog->snapshot.dbhdr.iCookie = iCookie;
    btLogUpdateDbhdr(pLog, sqlite4BtPageData(pOne));
  }
  sqlite4BtPageRelease(pOne);

  return rc;
}

    }
  }
  btHashClear(p);
}

static int btCheckpoint(BtLock *pLock){
  BtPager *p = (BtPager*)pLock;

  return sqlite4BtLogCheckpoint(p->pLog, 0);
}

static int btCleanup(BtLock *pLock){
  BtPager *p = (BtPager*)pLock;
  int rc = sqlite4BtLogClose(p->pLog, 1);
  p->pLog = 0;

    }
  }
  btHashClear(p);
}

static int btCheckpoint(BtLock *pLock){
  BtPager *p = (BtPager*)pLock;
  if( p->pLog==0 ) return SQLITE4_BUSY;
  return sqlite4BtLogCheckpoint(p->pLog, 0);
}

static int btCleanup(BtLock *pLock){
  BtPager *p = (BtPager*)pLock;
  int rc = sqlite4BtLogClose(p->pLog, 1);
  p->pLog = 0;

    }
  } {1 {no such table: AAAAAA}}
}

# Create a malformed file (a file that is not a valid database)
# and try to attach it
#
# UPDATE: This does not fail with LSM. 
#
do_test attach-8.1 {
  set fd [open test2.db w]
  puts $fd "This file is not a valid SQLite database"
  close $fd
  catchsql {
    ATTACH 'test2.db' AS t2;
  }
} {0 {}}
do_test attach-8.2 {
  db errorcode
} {0}
forcedelete test2.db
do_test attach-8.3 {
  sqlite4 db2 test2.db
  db2 eval {CREATE TABLE t1(x); BEGIN EXCLUSIVE}
  catchsql {
    ATTACH 'test2.db' AS t3;
  }

    }
  } {1 {no such table: AAAAAA}}
}

# Create a malformed file (a file that is not a valid database)
# and try to attach it
#


do_test attach-8.1 {
  set fd [open test2.db w]
  puts $fd "This file is not a valid SQLite database"
  close $fd
  catchsql {
    ATTACH 'test2.db' AS t2;
  }
} {1 {unable to open database: test2.db}}
do_test attach-8.2 {
  db errorcode
} {26}
forcedelete test2.db
do_test attach-8.3 {
  sqlite4 db2 test2.db
  db2 eval {CREATE TABLE t1(x); BEGIN EXCLUSIVE}
  catchsql {
    ATTACH 'test2.db' AS t3;
  }

# 2012 November 02
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix bt1

# Set tcl variable $str to the hex representation of the 24 byte string 
# located at the start of every bt database file.
set str ""
binary scan "SQLite4 bt database 0001" c24 I
foreach i $I {
  append str [format %02X $i ]
}

#-------------------------------------------------------------------------
# Test that, assuming there is no *-wal file, the bt module will refuse
# to open an existing database that does not contain a valid header.
#
do_test 1.0 {
  execsql {
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES('abcd');
  }

  db close
  list [file exists test.db] [file exists test.db-wal]
} {1 0}

do_test 1.1 { 
  hexio_read test.db 0 24 
} $str

do_test 1.2 { 
  sqlite4 db test.db
  execsql { SELECT * FROM t1 }
} {abcd}

do_test 1.3 { 
  db close
  hexio_write test.db  8 55555555

  list [catch {sqlite4 db test.db} msg] $msg
} {1 {file is encrypted or is not a database}}

#-------------------------------------------------------------------------
# Test that, if there is a *-wal file that contains a valid copy of page
# 1 (with the db header), it is possible to open the database even if
# the header at byte offset 0 is damaged.
#
reset_db
do_test 2.0 {
  execsql {
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(randomblob(20000));
  }
  db close
  list [file exists test.db] [file exists test.db-wal]
} {1 0}

do_test 2.1 {
  sqlite4 db test.db
  # This moves pages to the free-list. Meaning page 1 must be 
  # updated to set the pointer to the first free-list page.
  execsql { UPDATE t1 SET x = 'abcd' }
  db_save
  db close
  db_restore
  list [file exists test.db] [file exists test.db-wal]
} {1 1}

do_test 2.2 { 
  hexio_write test.db  8 55555555
  sqlite4 db test.db
  execsql { SELECT * FROM t1 }
} {abcd}

finish_test

#   quick
#   full
#
lappend ::testsuitelist xxx

test_suite "bt" -prefix "bt-" -description {
} -files {


aggerror.test
alter.test
alter3.test
alter4.test
analyze.test
analyze3.test
analyze4.test

#   quick
#   full
#
lappend ::testsuitelist xxx

test_suite "bt" -prefix "bt-" -description {
} -files {
bt1.test

aggerror.test
alter.test
alter3.test
alter4.test
analyze.test
analyze3.test
analyze4.test