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int test_lsm_zip_open(const char *zFilename, int bClear, TestDb **ppDb);
int test_lsm_small_open(const char *zFilename, int bClear, TestDb **ppDb);
int test_lsm_mt2(const char *zFilename, int bClear, TestDb **ppDb);
int test_lsm_mt3(const char *zFilename, int bClear, TestDb **ppDb);

int tdb_lsm_configure(lsm_db *, const char *);

/* Functions in lsmtest_tdb4.c */
int test_bt_open(const char *zFilename, int bClear, TestDb **ppDb);


/* Functions in testutil.c. */
int  testPrngInit(void);
u32  testPrngValue(u32 iVal);
void testPrngArray(u32 iVal, u32 *aOut, int nOut);
void testPrngString(u32 iVal, char *aOut, int nOut);

/* test5.c */
void test_mt(const char *zSystem, const char *zPattern, int *pRc);

/* lsmtest6.c */
void test_oom(const char *zPattern, int *pRc);
void testDeleteLsmdb(const char *zFile);

void testSaveDb(const char *zFile, const char *zAuxExt);
void testRestoreDb(const char *zFile, const char *zAuxExt);
void testCopyLsmdb(const char *zFrom, const char *zTo);

/* lsmtest7.c */
void test_api(const char *zPattern, int *pRc);

/* lsmtest8.c */
void do_writer_crash_test(const char *zPattern, int *pRc);

  if( *pRc==0 ){
    int rc;
    TestDb *pDb;
    rc = tdb_lsm_open(zCfg, zFile, 1, &pDb);
    if( rc==0 ){
      testWriteDatasourceRange(pDb, pData, 0, nRow, &rc);
      testClose(&pDb);
      if( rc==0 ) testSaveDb(zFile, "log");
    }
    *pRc = rc;
  }
}

void testSetupSavedBtdb(
  const char *zFile,
  Datasource *pData,
  int nRow,
  int *pRc
){
  if( *pRc==0 ){
    int rc;
    TestDb *pDb;
    rc = tdb_open("bt", zFile, 1, &pDb);
    if( rc==0 ){
      testWriteDatasourceRange(pDb, pData, 0, nRow, &rc);
      testClose(&pDb);
      if( rc==0 ) testSaveDb(zFile, "wal");
    }
    *pRc = rc;
  }
}

/*
** This function is a no-op if *pRc is non-zero when it is called.

    char zCksum[TEST_CKSUM_BYTES];
    TestDb *pDb;

    *pRc = tdb_lsm_open((bCompress?"compression=1 mmap=0":""), zFile, 0, &pDb);
    testCksumDatabase(pDb, zCksum);
    testClose(&pDb);

    if( *pRc==0 ){
      int r1 = 0;
      int r2 = -1;

      r1 = strcmp(zCksum, zExpect1);
      if( zExpect2 ) r2 = strcmp(zCksum, zExpect2);
      if( r1 && r2 ){
        if( zExpect2 ){
          testPrintError("testCompareCksumLsmdb: \"%s\" != (\"%s\" OR \"%s\")",
              zCksum, zExpect1, zExpect2
          );
        }else{
          testPrintError("testCompareCksumLsmdb: \"%s\" != \"%s\"",
              zCksum, zExpect1
          );
        }
        *pRc = 1;
        test_failed();
      }
    }
  }
}

static void testCompareCksumBtdb(
  const char *zFile,              /* Path to LSM database */
  const char *zExpect1,           /* Expected checksum 1 */
  const char *zExpect2,           /* Expected checksum 2 (or NULL) */
  int *pRc                        /* IN/OUT: Test case error code */
){
  if( *pRc==0 ){
    char zCksum[TEST_CKSUM_BYTES];
    TestDb *pDb;

    *pRc = tdb_open("bt", zFile, 0, &pDb);
    testCksumDatabase(pDb, zCksum);
    testClose(&pDb);

    if( *pRc==0 ){
      int r1 = 0;
      int r2 = -1;

      r1 = strcmp(zCksum, zExpect1);
      if( zExpect2 ) r2 = strcmp(zCksum, zExpect2);
      if( r1 && r2 ){

  for(i=0; i<nIter && *pRc==0; i++){
    int iWork;
    int testrc = 0;

    testCaseProgress(i, nIter, testCaseNDot(), &iDot);

    /* Restore and open the database. */
    testRestoreDb(DBNAME, "log");
    testrc = tdb_lsm_open(azConfig[bCompress], DBNAME, 0, &pDb);
    assert( testrc==0 );

    /* Call lsm_work() on the db */
    tdb_lsm_prepare_sync_crash(pDb, 1 + (i%(nWork*2)));
    for(iWork=0; testrc==0 && iWork<nWork; iWork++){
      int nWrite = 0;

  for(i=0; i<nIter && *pRc==0; i++){
    int iIns;
    int testrc = 0;

    testCaseProgress(i, nIter, testCaseNDot(), &iDot);

    /* Restore and open the database. */
    testRestoreDb(DBNAME, "log");
    testrc = tdb_lsm_open("safety=2", DBNAME, 0, &pDb);
    assert( testrc==0 );

    /* Insert nInsert records into the database. Crash midway through. */
    tdb_lsm_prepare_sync_crash(pDb, 1 + (i%(nInsert+2)));
    for(iIns=0; iIns<nInsert; iIns++){
      void *pKey; int nKey;
      void *pVal; int nVal;

      testDatasourceEntry(pData, 100+iIns, &pKey, &nKey, &pVal, &nVal);
      testrc = tdb_write(pDb, pKey, nKey, pVal, nVal);
      if( testrc ) break;
    }
    tdb_close(pDb);

    /* Check that no data was lost when the system crashed. */
    testCompareCksumLsmdb(DBNAME, bCompress,
      testCksumArrayGet(pCksumDb, 100 + iIns),
      testCksumArrayGet(pCksumDb, 100 + iIns + 1),
      pRc
    );
  }

  testDatasourceFree(pData);
  testCksumArrayFree(pCksumDb);
}


/*
** This test verifies that if a system crash occurs while committing a
** transaction to the log file, no earlier transactions are lost or damaged.
*/
static void crash_test2b(int bCompress, int *pRc){
  const char *DBNAME = "testdb.bt";
  const DatasourceDefn defn = {TEST_DATASOURCE_RANDOM, 12, 16, 1000, 1000};

  const int nIter = 200;
  const int nInsert = 20;

  int i;
  int iDot = 0;
  Datasource *pData;
  CksumDb *pCksumDb;
  TestDb *pDb;

  /* Allocate datasource. And calculate the expected checksums. */
  pData = testDatasourceNew(&defn);
  pCksumDb = testCksumArrayNew(pData, 100, 100+nInsert+1, 1);

  /* Setup and save the initial database. */
  testSetupSavedBtdb(DBNAME, pData, 100, pRc);

  for(i=0; i<nIter && *pRc==0; i++){
    int iIns;
    int testrc = 0;

    testCaseProgress(i, nIter, testCaseNDot(), &iDot);

    /* Restore and open the database. */
    testRestoreDb(DBNAME, "wal");
    testrc = tdb_open("bt", DBNAME, 0, &pDb);
    assert( testrc==0 );

    /* Insert nInsert records into the database. Crash midway through. */
    tdb_bt_prepare_sync_crash(pDb, 1 + (i%(nInsert+2)));
    for(iIns=0; iIns<nInsert; iIns++){
      void *pKey; int nKey;
      void *pVal; int nVal;

      testDatasourceEntry(pData, 100+iIns, &pKey, &nKey, &pVal, &nVal);
      testrc = tdb_write(pDb, pKey, nKey, pVal, nVal);
      if( testrc ) break;
    }
    tdb_close(pDb);

    /* Check that no data was lost when the system crashed. */
    testCompareCksumBtdb(DBNAME, 
      testCksumArrayGet(pCksumDb, 100 + iIns),
      testCksumArrayGet(pCksumDb, 100 + iIns + 1),
      pRc
    );
  }

  testDatasourceFree(pData);

  /* Setup and save the initial database. */
  testSetupSavedLsmdb("", DBNAME, pData, 100, pRc);

  for(i=0; i<nIter && *pRc==0; i++){
    int iOpen;
    testCaseProgress(i, nIter, testCaseNDot(), &iDot);
    testRestoreDb(DBNAME, "log");

    for(iOpen=0; iOpen<5; iOpen++){
      /* Open the database. Insert 10 more records. */
      pDb = testOpen("lsm", 0, pRc);
      testWriteDatasourceRange(pDb, pData, 100+iOpen*10, 10, pRc);

      /* Schedule a crash simulation then close the db. */

void do_crash_test(const char *zPattern, int *pRc){
  struct Test {
    const char *zTest;
    void (*x)(int, int *);
    int bCompress;
  } aTest [] = {
    { "crash.bt.2",     crash_test2b, 0 },

    { "crash.lsm.1",     crash_test1, 0 },
    { "crash.lsm_zip.1", crash_test1, 1 },
    { "crash.lsm.2",     crash_test2, 0 },
    { "crash.lsm.3",     crash_test3, 0 },
  };
  int i;

  copy_file(zLog1, zLog2);
  copy_file(zShm1, zShm2);

  testFree(zLog1); testFree(zLog2); testFree(zShm1); testFree(zShm2);
}

/*
** File zFile is the path to a database. This function makes backups
** of the database file and its log as follows:
**
**     cp $(zFile)         $(zFile)-save
**     cp $(zFile)-$(zAux) $(zFile)-save-$(zAux)
**
** Function testRestoreDb() can be used to copy the files back in the
** other direction.
*/
void testSaveDb(const char *zFile, const char *zAux){
  char *zLog = testMallocPrintf("%s-%s", zFile, zAux);
  char *zFileSave = testMallocPrintf("%s-save", zFile);
  char *zLogSave = testMallocPrintf("%s-%s-save", zFile, zAux);

  unlink(zFileSave);
  unlink(zLogSave);
  copy_file(zFile, zFileSave);
  copy_file(zLog, zLogSave);

  testFree(zLog); testFree(zFileSave); testFree(zLogSave);
}

/*
** File zFile is the path to a database. This function restores
** a backup of the database made by a previous call to testSaveDb().
** Specifically, it does the equivalent of:
**
**     cp $(zFile)-save         $(zFile)
**     cp $(zFile)-save-$(zAux) $(zFile)-$(zAux)
*/
void testRestoreDb(const char *zFile, const char *zAux){
  char *zLog = testMallocPrintf("%s-%s", zFile, zAux);
  char *zFileSave = testMallocPrintf("%s-save", zFile);
  char *zLogSave = testMallocPrintf("%s-%s-save", zFile, zAux);

  copy_file(zFileSave, zFile);
  copy_file(zLogSave, zLog);

  testFree(zLog); testFree(zFileSave); testFree(zLogSave);
}

  if( rc==LSM_OK ) rc = lsm_open(pDb, LSMTEST6_TESTDB);

  for(ii=0; rc==LSM_OK && ii<ArraySize(azStr); ii+=2){
    rc = lsmWriteStr(pDb, azStr[ii], azStr[ii+1]);
  }
  lsm_close(pDb);

  testSaveDb(LSMTEST6_TESTDB, "log");
  assert( rc==LSM_OK );
}

static Datasource *getDatasource(void){
  const DatasourceDefn defn = { TEST_DATASOURCE_RANDOM, 10, 15, 200, 250 };
  return testDatasourceNew(&defn);
}

    void *pVal; int nVal;
    testDatasourceEntry(pData, ii, &pKey, &nKey, &pVal, &nVal);
    lsm_insert(pDb, pKey, nKey, pVal, nVal);
  }
  testDatasourceFree(pData);
  lsm_close(pDb);

  testSaveDb(LSMTEST6_TESTDB, "log");
  assert( rc==LSM_OK );
}

/*
** Test the results of OOM conditions in lsm_new().
*/
static void simple_oom_1(OomTest *pOom){

}

static void simple_oom_5(OomTest *pOom){
  Datasource *pData = getDatasource();
  int rc = LSM_OK;
  lsm_db *pDb;

  testRestoreDb(LSMTEST6_TESTDB, "log");
  testOomOpen(pOom, LSMTEST6_TESTDB, &pDb, &rc);

  testOomFetchData(pOom, pDb, pData, 3333, &rc);
  testOomFetchData(pOom, pDb, pData, 0, &rc);
  testOomFetchData(pOom, pDb, pData, 4999, &rc);

  lsm_close(pDb);
  testDatasourceFree(pData);
}

static void simple_oom_6(OomTest *pOom){
  Datasource *pData = getDatasource();
  int rc = LSM_OK;
  lsm_db *pDb;

  testRestoreDb(LSMTEST6_TESTDB, "log");
  testOomOpen(pOom, LSMTEST6_TESTDB, &pDb, &rc);

  testOomWriteData(pOom, pDb, pData, 5000, &rc);
  testOomWriteData(pOom, pDb, pData, 5001, &rc);
  testOomWriteData(pOom, pDb, pData, 5002, &rc);
  testOomFetchData(pOom, pDb, pData, 5001, &rc);
  testOomFetchData(pOom, pDb, pData, 1234, &rc);

  lsm_close(pDb);
  testDatasourceFree(pData);
}

static void simple_oom_7(OomTest *pOom){
  Datasource *pData = getDatasource();
  int rc = LSM_OK;
  lsm_db *pDb;

  testRestoreDb(LSMTEST6_TESTDB, "log");
  testOomOpen(pOom, LSMTEST6_TESTDB, &pDb, &rc);
  testOomScan(pOom, pDb, 0, "abc", 3, 20, &rc);
  lsm_close(pDb);
  testDatasourceFree(pData);
}

static void simple_oom_8(OomTest *pOom){
  Datasource *pData = getDatasource();
  int rc = LSM_OK;
  lsm_db *pDb;
  testRestoreDb(LSMTEST6_TESTDB, "log");
  testOomOpen(pOom, LSMTEST6_TESTDB, &pDb, &rc);
  testOomScan(pOom, pDb, 1, "xyz", 3, 20, &rc);
  lsm_close(pDb);
  testDatasourceFree(pData);
}

/*

  *ppDb = (TestDb *)pDb;
  return 0;
}
/* 
** End wrapper for SQLite.
*************************************************************************/






































































































































































































































































































/*************************************************************************
** Begin exported functions.
*/
static struct Lib {
  const char *zName;
  const char *zDefaultDb;
  int (*xOpen)(const char *zFilename, int bClear, TestDb **ppDb);
} aLib[] = {
  { "bt",           "testdb.bt",        test_bt_open },
  { "sqlite3",      "testdb.sqlite",    sql_open },
  { "lsm_small",    "testdb.lsm_small", test_lsm_small_open },
  { "lsm_lomem",    "testdb.lsm_lomem", test_lsm_lomem_open },
#ifdef HAVE_ZLIB
  { "lsm_zip",      "testdb.lsm_zip",   test_lsm_zip_open },
#endif
  { "lsm",          "testdb.lsm",       test_lsm_open },

** illegal to call them with any other type of database handle specified
** as an argument.
*/
void tdb_lsm_enable_log(TestDb *pDb, int bEnable);
void tdb_lsm_application_crash(TestDb *pDb);
void tdb_lsm_prepare_system_crash(TestDb *pDb);
void tdb_lsm_system_crash(TestDb *pDb);



void tdb_lsm_prepare_sync_crash(TestDb *pDb, int iSync);


void tdb_lsm_safety(TestDb *pDb, int eMode);
void tdb_lsm_config_work_hook(TestDb *pDb, void (*)(lsm_db *, void *), void *);
void tdb_lsm_write_hook(TestDb *, void(*)(void*,int,lsm_i64,int,int), void*);
int tdb_lsm_config_str(TestDb *pDb, const char *zStr);

/*************************************************************************
** Start of bt specific things. From lsmtest_tdb4.c.
*/

/*
** Simulate a system crash during the iSync'th call to xSync(). Passing
** iSync==1 means crash the next time xSync is called.
*/
void tdb_bt_prepare_sync_crash(TestDb *pDb, int iSync);

#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif

#endif

/*
** This file contains the TestDb bt wrapper.
*/

#include "lsmtest_tdb.h"
#include "lsmtest.h"
#include <unistd.h>
#include "bt.h"

typedef struct BtDb BtDb;
typedef struct BtFile BtFile;

/*
** Each database or log file opened by a database handle is wrapped by
** an object of the following type.
*/
struct BtFile {
  BtDb *pBt;                      /* Database handle that opened this file */
  bt_file *pFile;                 /* File handle belonging to underlying VFS */
  int nSectorSize;                /* Size of sectors in bytes */
  int nSector;                    /* Allocated size of nSector array */
  u8 **apSector;                  /* Original sector data */
};

/*
** nCrashSync:
**   If this value is non-zero, then a "crash-test" is running. If
**   nCrashSync==1, then the crash is simulated during the very next 
**   call to the xSync() VFS method (on either the db or log file).
**   If nCrashSync==2, the following call to xSync(), and so on.
**
** bCrash:
**   After a crash is simulated, this variable is set. Any subsequent
**   attempts to write to a file or modify the file system in any way 
**   fail once this is set. All the caller can do is close the connection.
*/
struct BtDb {
  TestDb base;                    /* Base class */
  bt_db *pBt;                     /* bt database handle */
  sqlite4_env *pEnv;              /* SQLite environment (for malloc/free) */
  bt_env *pVfs;                   /* Underlying VFS */

  /* Space for bt_fetch() results */
  u8 *aBuffer;                    /* Space to store results */
  int nBuffer;                    /* Allocated size of aBuffer[] in bytes */

  /* Stuff used for crash test simulation */
  BtFile *apFile[2];              /* Database and log files used by pBt */
  bt_env env;                     /* Private VFS for this object */
  int nCrashSync;                 /* Number of syncs until crash (see above) */
  int bCrash;                     /* True once a crash has been simulated */
};

static int btVfsFullpath(
  sqlite4_env *pEnv, 
  bt_env *pVfs, 
  const char *z, 
  char **pzOut
){
  BtDb *pBt = (BtDb*)pVfs->pVfsCtx;
  if( pBt->bCrash ) return SQLITE4_IOERR;
  return pBt->pVfs->xFullpath(pEnv, pBt->pVfs, z, pzOut);
}

static int btVfsOpen(
  sqlite4_env *pEnv, 
  bt_env *pVfs, 
  const char *zFile, 
  int flags, bt_file **ppFile
){
  BtFile *p;
  BtDb *pBt = (BtDb*)pVfs->pVfsCtx;
  int rc;

  if( pBt->bCrash ) return SQLITE4_IOERR;

  p = (BtFile*)testMalloc(sizeof(BtFile));
  if( !p ) return SQLITE4_NOMEM;
  assert( pBt->apFile[0]==0 || pBt->apFile[1]==0 );
  pBt->apFile[pBt->apFile[0]!=0] = p;

  p->pBt = pBt; rc = pBt->pVfs->xOpen(pEnv, pVfs, zFile, flags, &p->pFile);
  if( rc!=SQLITE4_OK ){
    testFree(p);
    p = 0;
  }

  *ppFile = (bt_file*)p;
  return rc;
}

static int btVfsSize(bt_file *pFile, sqlite4_int64 *piRes){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xSize(p->pFile, piRes);
}

static int btVfsRead(bt_file *pFile, sqlite4_int64 iOff, void *pBuf, int nBuf){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xRead(p->pFile, iOff, pBuf, nBuf);
}

static int btFlushSectors(BtFile *p){
  sqlite4_int64 iSz;
  int rc;
  int i;
  u8 *aTmp = 0;

  rc = p->pBt->pVfs->xSize(p->pFile, &iSz);
  for(i=0; rc==SQLITE4_OK && i<p->nSector; i++){
    if( p->pBt->bCrash && p->apSector[i] ){

      /* The system is simulating a crash. There are three choices for
      ** this sector:
      **
      **   1) Leave it as it is (simulating a successful write),
      **   2) Restore the original data (simulating a lost write),
      **   3) Populate the disk sector with garbage data.
      */
      sqlite4_int64 iSOff = p->nSectorSize*i;
      int nWrite = MIN(p->nSectorSize, iSz - iSOff);

      if( nWrite ){
        u8 *aWrite = 0;
        int iOpt = (testPrngValue(i) % 3) + 1;
        if( iOpt==1 ){
          aWrite = p->apSector[i];
        }else if( iOpt==3 ){
          if( aTmp==0 ) aTmp = testMalloc(p->nSectorSize);
          aWrite = aTmp;
          testPrngArray(i*13, (u32*)aWrite, nWrite/sizeof(u32));
        }

#if 0
fprintf(stderr, "handle sector %d with %s\n", i, 
    iOpt==1 ? "rollback" : iOpt==2 ? "write" : "omit"
);
fflush(stderr);
#endif

        if( aWrite ){
          rc = p->pBt->pVfs->xWrite(p->pFile, iSOff, aWrite, nWrite);
        }
      }
    }
    testFree(p->apSector[i]);
    p->apSector[i] = 0;
  }

  testFree(aTmp);
  return rc;
}

static int btSaveSectors(BtFile *p, sqlite4_int64 iOff, int nBuf){
  int rc;
  sqlite4_int64 iSz;              /* Size of file on disk */
  int iFirst;                     /* First sector affected */
  int iSector;                    /* Current sector */
  int iLast;                      /* Last sector affected */

  if( p->nSectorSize==0 ){
    p->nSectorSize = p->pBt->pVfs->xSectorSize(p->pFile);
    if( p->nSectorSize<512 ) p->nSectorSize = 512;
  }
  iLast = (iOff+nBuf) / p->nSectorSize;
  iFirst = iOff / p->nSectorSize;

  rc = p->pBt->pVfs->xSize(p->pFile, &iSz);
  for(iSector=iFirst; rc==SQLITE4_OK && iSector<=iLast; iSector++){
    int nRead;
    sqlite4_int64 iSOff = iSector * p->nSectorSize;
    u8 *aBuf = testMalloc(p->nSectorSize);
    nRead = MIN(p->nSectorSize, (iSz - iSOff));
    if( nRead>0 ){
      rc = p->pBt->pVfs->xRead(p->pFile, iSOff, aBuf, nRead);
    }

    while( rc==SQLITE4_OK && iSector>=p->nSector ){
      int nNew = p->nSector + 32;
      u8 **apNew = (u8**)testMalloc(nNew * sizeof(u8*));
      memcpy(apNew, p->apSector, p->nSector*sizeof(u8*));
      testFree(p->apSector);
      p->apSector = apNew;
      p->nSector = nNew;
    }

    p->apSector[iSector] = aBuf;
  }

  return rc;
}

static int btVfsWrite(bt_file *pFile, sqlite4_int64 iOff, void *pBuf, int nBuf){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  if( p->pBt->nCrashSync ){
    btSaveSectors(p, iOff, nBuf);
  }
  return p->pBt->pVfs->xWrite(p->pFile, iOff, pBuf, nBuf);
}

static int btVfsTruncate(bt_file *pFile, sqlite4_int64 iOff){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xTruncate(p->pFile, iOff);
}

static int btVfsSync(bt_file *pFile){
  int rc = SQLITE4_OK;
  BtFile *p = (BtFile*)pFile;
  BtDb *pBt = p->pBt;

  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  if( pBt->nCrashSync ){
    pBt->nCrashSync--;
    pBt->bCrash = (pBt->nCrashSync==0);
    if( pBt->bCrash ){
      btFlushSectors(pBt->apFile[0]);
      btFlushSectors(pBt->apFile[1]);
      rc = SQLITE4_IOERR;
    }else{
      btFlushSectors(p);
    }
  }

  if( rc==SQLITE4_OK ){
    rc = p->pBt->pVfs->xSync(p->pFile);
  }
  return rc;
}

static int btVfsSectorSize(bt_file *pFile){
  BtFile *p = (BtFile*)pFile;
  return p->pBt->pVfs->xSectorSize(p->pFile);
}

static int btVfsClose(bt_file *pFile){
  BtFile *p = (BtFile*)pFile;
  int rc;
  assert( p->pBt->apFile[0]==p || p->pBt->apFile[1]==p );
  btFlushSectors(p);
  testFree(p->apSector);
  rc = p->pBt->pVfs->xClose(p->pFile);
  testFree(p);
  return rc;
}

static int btVfsUnlink(sqlite4_env *pEnv, bt_env *pVfs, const char *zFile){
  BtDb *pBt = (BtDb*)pVfs->pVfsCtx;
  if( pBt->bCrash ) return SQLITE4_IOERR;
  return pBt->pVfs->xUnlink(pEnv, pBt->pVfs, zFile);
}

static int btVfsLock(bt_file *pFile, int iLock, int eType){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xLock(p->pFile, iLock, eType);
}

static int btVfsTestLock(bt_file *pFile, int iLock, int nLock, int eType){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xTestLock(p->pFile, iLock, nLock, eType);
}

static int btVfsShmMap(bt_file *pFile, int iChunk, int sz, void **ppOut){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xShmMap(p->pFile, iChunk, sz, ppOut);
}

static void btVfsShmBarrier(bt_file *pFile){
  BtFile *p = (BtFile*)pFile;
  return p->pBt->pVfs->xShmBarrier(p->pFile);
}

static int btVfsShmUnmap(bt_file *pFile, int bDelete){
  BtFile *p = (BtFile*)pFile;
  if( p->pBt->bCrash ) return SQLITE4_IOERR;
  return p->pBt->pVfs->xShmUnmap(p->pFile, bDelete);
}

static int bt_close(TestDb *pTestDb){
  BtDb *p = (BtDb*)pTestDb;
  free(p->aBuffer);
  return sqlite4BtClose(p->pBt);
}

static int btMinTransaction(BtDb *p, int iMin, int *piLevel){
  int iLevel;
  int rc = SQLITE4_OK;

  iLevel = sqlite4BtTransactionLevel(p->pBt);
  if( iLevel<iMin ){ 
    rc = sqlite4BtBegin(p->pBt, iMin); 
    *piLevel = iLevel;
  }else{
    *piLevel = -1;
  }

  return rc;
}
static int btRestoreTransaction(BtDb *p, int iLevel, int rcin){
  int rc = rcin;
  if( iLevel>=0 ){
    if( rc==SQLITE4_OK ){
      rc = sqlite4BtCommit(p->pBt, iLevel);
    }else{
      sqlite4BtRollback(p->pBt, iLevel);
    }
    assert( iLevel==sqlite4BtTransactionLevel(p->pBt) );
  }
  return rc;
}

static int bt_write(TestDb *pTestDb, void *pK, int nK, void *pV, int nV){
  BtDb *p = (BtDb*)pTestDb;
  int iLevel;
  int rc;

  rc = btMinTransaction(p, 2, &iLevel);
  if( rc==SQLITE4_OK ){
    rc = sqlite4BtReplace(p->pBt, pK, nK, pV, nV);
    rc = btRestoreTransaction(p, iLevel, rc);
  }
  return rc;
}

static int bt_delete(TestDb *pTestDb, void *pK, int nK){
  return bt_write(pTestDb, pK, nK, 0, -1);
}

static int bt_delete_range(
  TestDb *pTestDb, 
  void *pKey1, int nKey1,
  void *pKey2, int nKey2
){
  BtDb *p = (BtDb*)pTestDb;
  bt_cursor *pCsr = 0;
  int rc = SQLITE4_OK;
  int iLevel;

  rc = btMinTransaction(p, 2, &iLevel);
  if( rc==SQLITE4_OK ){
    rc = sqlite4BtCsrOpen(p->pBt, 0, &pCsr);
  }
  while( rc==SQLITE4_OK ){
    const void *pK;
    int n;
    int nCmp;
    int res;

    rc = sqlite4BtCsrSeek(pCsr, pKey1, nKey1, BT_SEEK_GE);
    if( rc==SQLITE4_INEXACT ) rc = SQLITE4_OK;
    if( rc!=SQLITE4_OK ) break;

    rc = sqlite4BtCsrKey(pCsr, &pK, &n);
    if( rc!=SQLITE4_OK ) break;

    nCmp = MIN(n, nKey1);
    res = memcmp(pKey1, pK, nCmp);
    assert( res<0 || (res==0 && nKey1<=n) );
    if( res==0 && nKey1==n ){
      rc = sqlite4BtCsrNext(pCsr);
      if( rc!=SQLITE4_OK ) break;
      rc = sqlite4BtCsrKey(pCsr, &pK, &n);
      if( rc!=SQLITE4_OK ) break;
    }

    nCmp = MIN(n, nKey2);
    res = memcmp(pKey2, pK, nCmp);
    if( res<0 || (res==0 && nKey2<=n) ) break;
    
    rc = sqlite4BtDelete(pCsr);
  }
  if( rc==SQLITE4_NOTFOUND ) rc = SQLITE4_OK;

  sqlite4BtCsrClose(pCsr);

  rc = btRestoreTransaction(p, iLevel, rc);
  return rc;
}

static int bt_fetch(
  TestDb *pTestDb, 
  void *pK, int nK, 
  void **ppVal, int *pnVal
){
  BtDb *p = (BtDb*)pTestDb;
  bt_cursor *pCsr = 0;
  int iLevel;
  int rc = SQLITE4_OK;

  iLevel = sqlite4BtTransactionLevel(p->pBt);
  if( iLevel==0 ){ 
    rc = sqlite4BtBegin(p->pBt, 1); 
    if( rc!=SQLITE4_OK ) return rc;
  }

  rc = sqlite4BtCsrOpen(p->pBt, 0, &pCsr);
  if( rc==SQLITE4_OK ){
    rc = sqlite4BtCsrSeek(pCsr, pK, nK, BT_SEEK_EQ);
    if( rc==SQLITE4_OK ){
      const void *pV = 0;
      int nV = 0;
      rc = sqlite4BtCsrData(pCsr, 0, -1, &pV, &nV);
      if( rc==SQLITE4_OK ){
        if( nV>p->nBuffer ){
          free(p->aBuffer);
          p->aBuffer = (u8*)malloc(nV*2);
          p->nBuffer = nV*2;
        }
        memcpy(p->aBuffer, pV, nV);
        *pnVal = nV;
        *ppVal = (void*)(p->aBuffer);
      }

    }else if( rc==SQLITE4_INEXACT || rc==SQLITE4_NOTFOUND ){
      *ppVal = 0;
      *pnVal = -1;
      rc = SQLITE4_OK;
    }
    sqlite4BtCsrClose(pCsr);
  }

  if( iLevel==0 ) sqlite4BtCommit(p->pBt, 0); 
  return rc;
}

static int bt_scan(
  TestDb *pTestDb,
  void *pCtx,
  int bReverse,
  void *pFirst, int nFirst,
  void *pLast, int nLast,
  void (*xCallback)(void *, void *, int , void *, int)
){
  BtDb *p = (BtDb*)pTestDb;
  bt_cursor *pCsr = 0;
  int rc;
  int iLevel;

  rc = btMinTransaction(p, 1, &iLevel);

  if( rc==SQLITE4_OK ){
    rc = sqlite4BtCsrOpen(p->pBt, 0, &pCsr);
  }
  if( rc==SQLITE4_OK ){
    if( bReverse ){
      if( pLast ){
        rc = sqlite4BtCsrSeek(pCsr, pLast, nLast, BT_SEEK_LE);
      }else{
        rc = sqlite4BtCsrLast(pCsr);
      }
    }else{
      rc = sqlite4BtCsrSeek(pCsr, pFirst, nFirst, BT_SEEK_GE);
    }
    if( rc==SQLITE4_INEXACT ) rc = SQLITE4_OK;

    while( rc==SQLITE4_OK ){
      const void *pK = 0; int nK = 0;
      const void *pV = 0; int nV = 0;

      rc = sqlite4BtCsrKey(pCsr, &pK, &nK);
      if( rc==SQLITE4_OK ){
        rc = sqlite4BtCsrData(pCsr, 0, -1, &pV, &nV);
      }

      if( rc!=SQLITE4_OK ) break;
      if( bReverse ){
        if( pFirst ){
          int res;
          int nCmp = MIN(nK, nFirst);
          res = memcmp(pFirst, pK, nCmp);
          if( res>0 || (res==0 && nK<nFirst) ) break;
        }
      }else{
        if( pLast ){
          int res;
          int nCmp = MIN(nK, nLast);
          res = memcmp(pLast, pK, nCmp);
          if( res<0 || (res==0 && nK>nLast) ) break;
        }
      }

      xCallback(pCtx, (void*)pK, nK, (void*)pV, nV);
      if( bReverse ){
        rc = sqlite4BtCsrPrev(pCsr);
      }else{
        rc = sqlite4BtCsrNext(pCsr);
      }
    }
    if( rc==SQLITE4_NOTFOUND ) rc = SQLITE4_OK;

    sqlite4BtCsrClose(pCsr);
  }

  rc = btRestoreTransaction(p, iLevel, rc);
  return rc;
}

static int bt_begin(TestDb *pTestDb, int iLvl){
  BtDb *p = (BtDb*)pTestDb;
  int rc = sqlite4BtBegin(p->pBt, iLvl);
  return rc;
}

static int bt_commit(TestDb *pTestDb, int iLvl){
  BtDb *p = (BtDb*)pTestDb;
  int rc = sqlite4BtCommit(p->pBt, iLvl);
  return rc;
}

static int bt_rollback(TestDb *pTestDb, int iLvl){
  BtDb *p = (BtDb*)pTestDb;
  int rc = sqlite4BtRollback(p->pBt, iLvl);
  return rc;
}

int test_bt_open(const char *zFilename, int bClear, TestDb **ppDb){

  static const DatabaseMethods SqlMethods = {
    bt_close,
    bt_write,
    bt_delete,
    bt_delete_range,
    bt_fetch,
    bt_scan,
    bt_begin,
    bt_commit,
    bt_rollback
  };
  BtDb *p = 0;
  bt_db *pBt = 0;
  int rc;
  sqlite4_env *pEnv = sqlite4_env_default();

  if( bClear && zFilename && zFilename[0] ){
    char *zLog = sqlite3_mprintf("%s-wal", zFilename);
    unlink(zFilename);
    unlink(zLog);
    sqlite3_free(zLog);
  }
  
  rc = sqlite4BtNew(pEnv, sizeof(BtDb), &pBt);
  if( rc==SQLITE4_OK ){
    p = (BtDb*)sqlite4BtExtra(pBt);
    p->base.pMethods = &SqlMethods;
    p->pBt = pBt;
    p->pEnv = pEnv;

    p->env.pVfsCtx = (void*)p;
    p->env.xFullpath = btVfsFullpath;
    p->env.xOpen = btVfsOpen;
    p->env.xSize = btVfsSize;
    p->env.xRead = btVfsRead;
    p->env.xWrite = btVfsWrite;
    p->env.xTruncate = btVfsTruncate;
    p->env.xSync = btVfsSync;
    p->env.xSectorSize = btVfsSectorSize;
    p->env.xClose = btVfsClose;
    p->env.xUnlink = btVfsUnlink;
    p->env.xLock = btVfsLock;
    p->env.xTestLock = btVfsTestLock;
    p->env.xShmMap = btVfsShmMap;
    p->env.xShmBarrier = btVfsShmBarrier;
    p->env.xShmUnmap = btVfsShmUnmap;

    sqlite4BtControl(pBt, BT_CONTROL_GETVFS, (void*)&p->pVfs);
    sqlite4BtControl(pBt, BT_CONTROL_SETVFS, (void*)&p->env);

    rc = sqlite4BtOpen(pBt, zFilename);
  }

  if( rc!=SQLITE4_OK && p ){
    bt_close(&p->base);
  }

  *ppDb = &p->base;
  return rc;
}

void tdb_bt_prepare_sync_crash(TestDb *pTestDb, int iSync){
  BtDb *p = (BtDb*)pTestDb;
  assert( pTestDb->pMethods->xClose==bt_close );
  assert( p->bCrash==0 );
  p->nCrashSync = iSync;
}

             $(TOP)/lsm-test/lsmtest5.c $(TOP)/lsm-test/lsmtest6.c           \
             $(TOP)/lsm-test/lsmtest7.c $(TOP)/lsm-test/lsmtest8.c           \
             $(TOP)/lsm-test/lsmtest9.c                                      \
             $(TOP)/lsm-test/lsmtest_datasource.c \
             $(TOP)/lsm-test/lsmtest_func.c $(TOP)/lsm-test/lsmtest_io.c     \
             $(TOP)/lsm-test/lsmtest_main.c $(TOP)/lsm-test/lsmtest_mem.c    \
             $(TOP)/lsm-test/lsmtest_tdb.c $(TOP)/lsm-test/lsmtest_tdb3.c    \
             $(TOP)/lsm-test/lsmtest_tdb4.c \
             $(TOP)/lsm-test/lsmtest_util.c 

LSMTESTHDR = $(TOP)/lsm-test/lsmtest.h $(TOP)/lsm-test/lsmtest_tdb.h

# This is the default Makefile target.  The objects listed here
# are what get build when you type just "make" with no arguments.
#

test:	testfixture$(EXE) sqlite4$(EXE)
	./testfixture$(EXE) $(TOP)/test/src4.test

# Rules to build the 'lsmtest' application.
#
lsmtest$(EXE): libsqlite4.a $(LSMTESTSRC) $(LSMTESTHDR)
	$(TCPPX) -c $(TOP)/lsm-test/lsmtest_tdb2.cc
	$(TCCX) $(LSMTESTSRC) lsmtest_tdb2.o libsqlite4.a -o lsmtest$(EXE) $(THREADLIB) -lsqlite3 -llmdb -lstdc++


varint$(EXE):	$(TOP)/src/varint.c
	$(TCCX) -DVARINT_TOOL -o varint$(EXE) $(TOP)/src/varint.c

# The next two rules are used to support the "threadtest" target. Building
# threadtest runs a few thread-safety tests that are implemented in C. This

** BT_CONTROL_INFO:
**   If the second argument to sqlite4BtControl() is BT_CONTROL_INFO, then
**   the third is expected to be a pointer to an instance of type bt_info.
**   The "output" buffer must already be initialized. Before 
**   sqlite4BtControl() returns it appends debugging information to the
**   buffer. The specific information appended depends on the eType and
**   pgno member variables.
**
** BT_CONTROL_SETVFS:
**   The third argument is assumed to be a pointer to an instance of type
**   bt_env. The database handle takes a copy of this pointer (not a copy 
**   of the object) and uses it for all subsequent IO. It is the 
**   responsibility of the caller to ensure that the pointer is valid for
**   the lifetime of the database connection.
**
** BT_CONTROL_GETVFS:
**   The third argument is assumed to be of type (bt_env**). Before 
**   returning, the value pointed to is populated with a pointer to 
**   to the current bt_env object.
**
** BT_CONTROL_SAFETY:
**   The third argument is interpreted as a pointer to type (int). If
**   the value stored in the (int) location is 0, 1 or 2, then the current
**   b-tree safety level is set to 0, 1 or 2, respectively. Otherwise, the
**   integer value is set to the current safety level.
*/
#define BT_CONTROL_INFO   7706389
#define BT_CONTROL_SETVFS 7706390
#define BT_CONTROL_GETVFS 7706391
#define BT_CONTROL_SAFETY 7706392

int sqlite4BtControl(bt_db*, int op, void *pArg);


typedef struct bt_info bt_info;
struct bt_info {
  int eType;
  unsigned int pgno;
  sqlite4_buffer output;
};

/*
** File-system interface.
*/
typedef struct bt_env bt_env;
typedef struct bt_file bt_file;

/*
** xFullpath:
*/
struct bt_env {
  void *pVfsCtx;
  int (*xFullpath)(sqlite4_env*,bt_env*, const char *, char **);
  int (*xOpen)(sqlite4_env*,bt_env*, const char *, int flags, bt_file**);
  int (*xSize)(bt_file*, sqlite4_int64*);
  int (*xRead)(bt_file*, sqlite4_int64, void *, int);
  int (*xWrite)(bt_file*, sqlite4_int64, void *, int);
  int (*xTruncate)(bt_file*, sqlite4_int64);
  int (*xSync)(bt_file*);
  int (*xSectorSize)(bt_file*);
  int (*xClose)(bt_file*);
  int (*xUnlink)(sqlite4_env*,bt_env*, const char *);
  int (*xLock)(bt_file*, int, int);
  int (*xTestLock)(bt_file*, int, int, int);
  int (*xShmMap)(bt_file*, int, int, void **);
  void (*xShmBarrier)(bt_file*);
  int (*xShmUnmap)(bt_file*, int);
};

** Return a pointer to a buffer containing the name of the pager log file.
*/
#define BT_PAGERFILE_DATABASE 0
#define BT_PAGERFILE_LOG      1
#define BT_PAGERFILE_SHM      2
const char *sqlite4BtPagerFilename(BtPager*, int ePagerfile);

bt_env *sqlite4BtPagerGetEnv(BtPager*);
void sqlite4BtPagerSetEnv(BtPager*, bt_env*);

void sqlite4BtPagerSetSafety(BtPager*, int*);

/*
** End of bt_pager.c interface.
*************************************************************************/

/*************************************************************************
** File-system interface.
*/

























/* Flags for the 3rd argument to xOpen */
#define BT_OPEN_READONLY 0x0001

/* Candidate values for the 3rd argument to bt_env.xLock() */
#define BT_LOCK_UNLOCK 0
#define BT_LOCK_SHARED 1

  u32 *aOut                       /* OUT: Final checksum value output */
){
  assert( (nByte&0x00000007)==4 && nByte>=8 );
  btLogChecksum(nativeCksum, a, 8, aIn, aOut);
  btLogChecksum(nativeCksum, &a[4], nByte-4, aOut, aOut);
}

#define BT_PAGE_DEBUG 1
#define BT_VAL_DEBUG  0

static void btDebugTopology(BtLock *pLock, char *zStr, int iSide, u32 *aLog){
#if BT_PAGE_DEBUG
  fprintf(stderr, "%d:%s: (side=%d) %d..%d  %d..%d  %d..%d\n", 
      pLock->iDebugId, zStr, iSide,
      (int)aLog[0], (int)aLog[1], (int)aLog[2], 
      (int)aLog[3], (int)aLog[4], (int)aLog[5]
  );
  fflush(stderr);
#endif
}

#ifndef NDEBUG
void sqlite4BtDebugReadlock(BtLock *pLock, u32 iFirst, u32 iLast){
#if BT_PAGE_DEBUG
  static int nCall = 0;
  fprintf(stderr, "%d:%d: readlock=(%d..%d)\n",
      pLock->iDebugId, nCall++, (int)iFirst, (int)iLast
  );
  fflush(stderr);
#endif
}
#endif

#ifndef NDEBUG
static void btDebugCheckSnapshot(BtShmHdr *pHdr){
  u32 *aLog = pHdr->aLog;
  assert( pHdr->iNextFrame!=1 ||
      (aLog[0]==0 && aLog[1]==0 && aLog[2]==0 && aLog[3]==0)
  );

  fprintf(stderr, "%d:%d: checkpoint safepoint=%d\n",
      pLock->iDebugId, nCall++, (int)iSafe
  );
  fflush(stderr);
#endif
}
#else
#define btDebugLogSafepoint(x,y)
#endif

static void btDebugCkptPage(BtLock *pLock, u32 pgno, u8 *aData, int pgsz){
#if BT_PAGE_DEBUG
  static int nCall = 0;
  u32 aCksum[2];
  btLogChecksum(1, aData, pgsz, 0, aCksum);

static void binToStr(u8 *pIn, int nIn, u8 *pOut, int nOut){
  int i;
  int nCopy = MIN(nIn, (nOut-1));
  for(i=0; i<nCopy; i++){
    if( isprint(pIn[i]) ){
      pOut[i] = pIn[i];
    }else{
      pOut[i] = '.';
    }
  }
  pOut[i] = '\0';
}
void sqlite4BtDebugKV(
    BtLock *pLock, const char *zStr, u8 *pK, int nK, u8 *pV, int nV
){

** Return the offset of frame iFrame within the log file.
*/
static i64 btLogFrameOffset(BtLog *pLog, int pgsz, u32 iFrame){
  return 
      (i64)pLog->snapshot.nSector*2 
    + (i64)(iFrame-1) * (i64)(pgsz + sizeof(BtFrameHdr));
}

static int btLogSyncFile(BtLog *pLog, bt_file *pFd){
  bt_env *pVfs = pLog->pLock->pVfs;
  return pVfs->xSync(pFd);
}

static int btLogWriteData(BtLog *pLog, i64 iOff, u8 *aData, int nData){
  bt_env *pVfs = pLog->pLock->pVfs;
  return pVfs->xWrite(pLog->pFd, iOff, aData, nData);
}

static int btLogReadData(BtLog *pLog, i64 iOff, u8 *aData, int nData){

static int btLogRecover(BtLog *pLog){
  bt_env *pVfs = pLog->pLock->pVfs;
  i64 nByte = 0;                  /* Size of log file on disk */
  int rc;                         /* Return code */
  BtWalHdr *pHdr = 0;
  int iSlot = 0;
  FrameRecoverCtx ctx = {0, 0};
  BtWalHdr hdr1;
  BtWalHdr hdr2;

  /* Read a log file header from the start of the file. */
  rc = pVfs->xSize(pLog->pFd, &nByte);
  if( rc==SQLITE4_OK && nByte>0 ){

    rc = btLogReadHeader(pLog, 0, &hdr1);
    if( rc==SQLITE4_OK ){

      rc = btLogReadHeader(pLog, hdr1.nSector, &hdr2);
      if( rc==SQLITE4_NOTFOUND ){
        pHdr = &hdr1;
      }else if( rc==SQLITE4_OK ){
        int aGreater[3] = {1, 2, 0};
        pHdr = ((hdr2.iCnt==aGreater[hdr1.iCnt]) ? &hdr2 : &hdr1);
      }

      /* One or more transactions were recovered from the log file. */
      BtShm *pShm = btLogShm(pLog);
      pShm->ckpt.iWalHdr = (iSlot<<2) + pHdr->iCnt;
      pShm->ckpt.iFirstRead = pHdr->iFirstFrame;
      pShm->ckpt.iFirstRecover = pHdr->iFirstFrame;
      rc = btLogRollbackRecovery(pLog, &ctx);
      pLog->snapshot.iNextFrame = ctx.iNextFrame;
      pLog->snapshot.pgsz = pHdr->nPgsz;
      assert( pShm->ckpt.iFirstRead>0 );
    }
  }

  if( rc==SQLITE4_OK && ctx.iLast==0 ){
    /* No transactions were recovered from the log file. */
    BtDbhdr dbhdr;            /* Database header */
    btLogZeroSnapshot(pLog);

    /* Read the database file header to obtail values required
    ** by the snapshot.  */
    rc = btLogReadDbhdr(pLog, &dbhdr);
    pLog->snapshot.nPg = dbhdr.nPg;
    pLog->snapshot.pgsz = dbhdr.pgsz;
    pLog->snapshot.iCookie = dbhdr.cookie;
  }

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

/*
** Open the log file for pager pPager. If successful, return the BtLog* 
** handle via output variable *ppLog. If parameter bRecover is true, then
** also run database recovery before returning. In this case, the caller

** SQLITE4_NOTFOUND.
*/
int btLogRead(BtLog *pLog, u32 pgno, u8 *aData, u32 iSafe){
  const int pgsz = sqlite4BtPagerPagesize((BtPager*)(pLog->pLock));
  int rc = SQLITE4_NOTFOUND;
  u32 iFrame = 0;
  int i;


  u32 *aLog = pLog->snapshot.aLog;
  int iSafeIdx = sqlite4BtLogFrameToIdx(aLog, iSafe);

  /* Loop through regions (c), (b) and (a) of the log file. In that order. */
  for(i=2; i>=0 && rc==SQLITE4_NOTFOUND; i--){
    u32 iLo = pLog->snapshot.aLog[i*2+0];

  rc = btLogFindHash(pLog, iSide, iHash, &aHash, &aPgno, &iZero);
  if( rc==SQLITE4_OK ){
    memset(aHash, 0, sizeof(ht_slot)*HASHTABLE_NSLOT);
  }
  return rc;
}




static int btLogWriteFrame(BtLog *pLog, u32 pgno, u8 *aData, u32 nPg){
  const int pgsz = sqlite4BtPagerPagesize((BtPager*)(pLog->pLock));
  u32 *aLog = pLog->snapshot.aLog;
  int rc;                         /* Return code */
  u32 iFrame;                     /* Write this frame (numbered from 1) */
  u32 iNextFrame;                 /* Frame to write following this one */

  i64 iOff;                       /* Offset of log file to write to */


  BtFrameHdr frame;               /* Header for new frame */







































  /* Figure out the offset to write the current frame to. */
  iFrame = pLog->snapshot.iNextFrame;
  iOff = btLogFrameOffset(pLog, pgsz, iFrame);

  /* The current frame will be written to location pLog->snapshot.iNextFrame.
  ** This code determines where the following frame will be stored. There

    }
  }

  if( rc==SQLITE4_OK ){
    if( iNextFrame & 0x80000000 ){
      rc = SQLITE4_FULL;
    }else{
      u32 *a;                     /* Pointer to cksum of previous frame */

      /* Populate the frame header object. */
      memset(&frame, 0, sizeof(frame));
      frame.pgno = pgno;
      frame.iNext = iNextFrame;
      frame.nPg = nPg;
      a = pLog->snapshot.aFrameCksum;

    }

    aLog[5] = iFrame;
    memcpy(pLog->snapshot.aFrameCksum, frame.aCksum, sizeof(frame.aCksum));
  }
  btDebugCheckSnapshot(&pLog->snapshot);

  return rc;
}

/*
** Write a frame to the log file.
*/
int sqlite4BtLogWrite(BtLog *pLog, u32 pgno, u8 *aData, u32 nPg){
  const int pgsz = sqlite4BtPagerPagesize((BtPager*)(pLog->pLock));
  int rc = SQLITE4_OK;

  int nPad = 1;

  /* If this is a commit frame and the size of the database has changed,
  ** ensure that the log file contains at least one copy of page 1 written
  ** since the last checkpoint. This is required as a future checkpoint
  ** will need to update the nPg field in the database header located on
  ** page 1. */
  if( nPg && nPg!=pLog->snapshot.nPg ){
    BtPager *pPager = (BtPager *)(pLog->pLock);
    BtPage *pOne = 0;
    rc = sqlite4BtPageGet(pPager, 1, &pOne);
    if( rc==SQLITE4_OK ){
      rc = sqlite4BtLogWrite(pLog, 1, sqlite4BtPageData(pOne), 0);
      sqlite4BtPageRelease(pOne);
    }
    if( rc!=SQLITE4_OK ) return rc;
  }

  /* Handle a special case - if the log file is completely empty then
  ** this writer must write the first header into the WAL file. */
  if( btLogIsEmpty(pLog) ){
    BtWalHdr hdr;
    memset(&hdr, 0, sizeof(BtWalHdr));

    hdr.iMagic = BT_WAL_MAGIC;
    hdr.iVersion = BT_WAL_VERSION;
    hdr.nSector = pLog->snapshot.nSector;
    hdr.nPgsz = pgsz;
    hdr.iSalt1 = 22;
    hdr.iSalt2 = 23;
    hdr.iFirstFrame = 1;

    rc = btLogWriteHeader(pLog, 0, &hdr);
    if( rc!=SQLITE4_OK ) return rc;

    pLog->snapshot.aFrameCksum[0] = hdr.iSalt1;
    pLog->snapshot.aFrameCksum[1] = hdr.iSalt2;
    pLog->snapshot.iNextFrame = 1;
  }
  btDebugCheckSnapshot(&pLog->snapshot);

  rc = btLogWriteFrame(pLog, pgno, aData, nPg);

  /* If this is a COMMIT, sync the log and update the shared shm-header. */
  if( nPg ){
    int i;
    for(i=0; i<nPad && rc==SQLITE4_OK; i++){
      rc = btLogWriteFrame(pLog, pgno, aData, nPg);
    }
    if( rc==SQLITE4_OK ) rc = btLogSyncFile(pLog, pLog->pFd);
    if( rc==SQLITE4_OK ) rc = btLogUpdateSharedHdr(pLog);
  }

  return rc;
}

/*
** Return true if the checksum in BtShmHdr.aCksum[] matches the rest

/*
** Insert a new key/value pair or replace an existing one.
*/
int sqlite4BtReplace(bt_db *db, const void *pK, int nK, const void *pV, int nV){
  int rc = SQLITE4_OK;
  bt_cursor csr;

  sqlite4BtDebugKV((BtLock*)db->pPager, "replace", (u8*)pK, nK, (u8*)pV, nV);

  btCheckPageRefs(db);
  btCsrSetup(db, &csr);
  rc = btCsrSeek(&csr, pK, nK, BT_SEEK_GE, 1);
  if( rc==SQLITE4_OK ){
    /* The cursor currently points to an entry with key pK/nK. This call
    ** should therefore replace that entry. So delete it and then re-seek

int sqlite4BtGetCookie(bt_db *db, unsigned int *piVal){
  return sqlite4BtPagerGetCookie(db->pPager, piVal);
}

int sqlite4BtControl(bt_db *db, int op, void *pArg){
  int rc = SQLITE4_OK;

  switch( op ){
    case BT_CONTROL_INFO: {
      bt_info *pInfo = (bt_info*)pArg;
      int iTrans = sqlite4BtTransactionLevel(db);
      if( iTrans==0 ) rc = sqlite4BtBegin(db, 1);
      if( rc==SQLITE4_OK ){
        BtPage *pPg = 0;
        rc = sqlite4BtPageGet(db->pPager, pInfo->pgno, &pPg);
        if( rc==SQLITE4_OK ){
          u8 *aData;
          int nData;
          aData = sqlite4BtPageData(pPg);
          nData = sqlite4BtPagerPagesize(db->pPager);
          btPageToAscii(pInfo->pgno, aData, nData, &pInfo->output);
          sqlite4_buffer_append(&pInfo->output, "", 1);
          sqlite4BtPageRelease(pPg);
        }
        if( iTrans==0 ) rc = sqlite4BtCommit(db, 0);
      }
      break;
    }

    case BT_CONTROL_GETVFS: {
      *((bt_env**)pArg) = sqlite4BtPagerGetEnv(db->pPager);
      break;
    }

    case BT_CONTROL_SETVFS: {
      sqlite4BtPagerSetEnv(db->pPager, (bt_env*)pArg);
      break;
    }

    case BT_CONTROL_SAFETY: {
      int *pInt = (int*)pArg;
      sqlite4BtPagerSetSafety(db->pPager, pInt);
      break;
    }
  }

  return rc;
}

/*
** Pager object.
**
** nAutoCkpt:
**   If a transaction is committed and there are this many frames in the
**   log file, automatically run a checkpoint operation.
**
** iSafetyLevel:
**   Current safety level. 0==off, 1==normal, 2=full.
*/
struct BtPager {
  BtLock btl;                     /* Variables shared with bt_lock module */
  BtLog *pLog;                    /* Logging module */
  int iTransactionLevel;          /* Current transaction level (see bt.h) */
  int iSafetyLevel;               /* Current safety level */
  char *zFile;                    /* Database file name */
  int nFile;                      /* Length of string zFile in bytes */
  BtPageHash hash;                /* Hash table */
  BtPage *pDirty;                 /* List of all dirty pages */
  int nTotalRef;                  /* Total number of outstanding page refs */
  int nAutoCkpt;                  /* Auto-checkpoint when log is this large */
  int bDoAutoCkpt;                /* Do auto-checkpoint after next unlock */

  if( p->iTransactionLevel>=iLevel ){
    if( p->iTransactionLevel>=2 && iLevel<2 ){
      /* Commit the main write transaction. */
      rc = btCommitTransaction(p);
    }
    p->iTransactionLevel = iLevel;
    if( iLevel==0 ){
      int rc2 = btCloseReadTransaction(p);
      if( rc==SQLITE4_OK ) rc = rc2;
    }
  }
  return rc;
}

int sqlite4BtPagerRollback(BtPager *p, int iLevel){
  int rc = SQLITE4_OK;

      }else{
        memset(pRet->aData, 0, p->pgsz);
      }

      if( rc==SQLITE4_OK ){
        rc = btHashAdd(p, pRet);
      }

      if( rc!=SQLITE4_OK ){
        btFreePage(p, pRet);
        pRet = 0;
      }else{
        sqlite4BtDebugReadPage(&p->btl, pgno, pRet->aData, p->pgsz);
      }
    }

  }

  assert( (pRet!=0)==(rc==SQLITE4_OK) );
  if( rc==SQLITE4_OK ){
    p->nTotalRef++;
    pRet->nRef++;
  }

      assert( ePagerfile==BT_PAGERFILE_SHM );
      zTail = "-shm";
      break;
  }
  memcpy(&p->zFile[p->nFile], zTail, strlen(zTail)+1);
  return p->zFile;
}

bt_env *sqlite4BtPagerGetEnv(BtPager *p){
  return p->btl.pVfs;
}
void sqlite4BtPagerSetEnv(BtPager *p, bt_env *pVfs){
  p->btl.pVfs = pVfs;
}

void sqlite4BtPagerSetSafety(BtPager *pPager, int *piVal){
  int iVal = *piVal;
  if( iVal>=0 && iVal<=2 ){
    pPager->iSafetyLevel = iVal;
  }
  *piVal = pPager->iSafetyLevel;
}

#ifndef NDEBUG
int sqlite4BtPagerRefcount(BtPager *p){
  return p->nTotalRef;
}
#endif

  }

  return rc;
}

static int btPosixOsSync(bt_file *pFile){
  int rc = SQLITE4_OK;
#ifndef SQLITE_NO_SYNC
  PosixFile *p = (PosixFile *)pFile;
  int prc = 0;

#if 0
  if( p->pMap ){
    prc = msync(p->pMap, p->nMap, MS_SYNC);
  }