SQLite4  Check-in [d37b353a55]

}

static int testEnvUnlink(lsm_env *pEnv, const char *zFile){
  lsm_env *pRealEnv = tdb_lsm_env();
  unused_parameter(pEnv);
  return pRealEnv->xUnlink(pRealEnv, zFile);
}

static int testEnvLock(lsm_file *pFile, int iLock, int eType){
  LsmFile *p = (LsmFile *)pFile;
  lsm_env *pRealEnv = tdb_lsm_env();
  return pRealEnv->xLock(p->pReal, iLock, eType);
}

static int testEnvShmMap(lsm_file *pFile, int iRegion, int sz, void **pp){
  LsmFile *p = (LsmFile *)pFile;
  lsm_env *pRealEnv = tdb_lsm_env();
  return pRealEnv->xShmMap(p->pReal, iRegion, sz, pp);
}

static void testEnvShmBarrier(void){
}

static int testEnvShmUnmap(lsm_file *pFile, int bDel){
  LsmFile *p = (LsmFile *)pFile;
  lsm_env *pRealEnv = tdb_lsm_env();
  return pRealEnv->xShmUnmap(p->pReal, bDel);
}

static void doSystemCrash(LsmDb *pDb){
  lsm_env *pEnv = tdb_lsm_env();
  int iFile;
  int iSeed = pDb->aFile[0].nSector + pDb->aFile[1].nSector;

  char *zFile = pDb->zName;

    { "safety",         0, LSM_CONFIG_SAFETY },
    { "autowork",       0, LSM_CONFIG_AUTOWORK },
    { "log_size",       0, LSM_CONFIG_LOG_SIZE },
    { "mmap",           0, LSM_CONFIG_MMAP },
    { "use_log",        0, LSM_CONFIG_USE_LOG },
    { "nmerge",         0, LSM_CONFIG_NMERGE },
    { "max_freelist",   0, LSM_CONFIG_MAX_FREELIST },
    { "multi_proc",     0, LSM_CONFIG_MULTIPLE_PROCESSES },
    { "worker_nmerge",  1, LSM_CONFIG_NMERGE },
    { 0, 0 }
  };
  const char *z = zStr;

  while( z[0] && pDb ){
    const char *zStart;

  pDb->env.xTruncate = testEnvTruncate;
  pDb->env.xSync = testEnvSync;
  pDb->env.xSectorSize = testEnvSectorSize;
  pDb->env.xRemap = testEnvRemap;
  pDb->env.xFileid = testEnvFileid;
  pDb->env.xClose = testEnvClose;
  pDb->env.xUnlink = testEnvUnlink;
  pDb->env.xLock = testEnvLock;
  pDb->env.xShmBarrier = testEnvShmBarrier;
  pDb->env.xShmMap = testEnvShmMap;
  pDb->env.xShmUnmap = testEnvShmUnmap;

  rc = lsm_new(&pDb->env, &pDb->db);
  if( rc==LSM_OK ){
    lsm_config_log(pDb->db, xLog, 0);
    lsm_config_work_hook(pDb->db, xWorkHook, (void *)pDb);
    tdb_lsm_config_str((TestDb *)pDb, zCfg);
    rc = lsm_open(pDb->db, zFilename);

/* 64-bit integer type used for file offsets. */
typedef long long int lsm_i64;              /* 64-bit signed integer type */

/* Forward reference */
typedef struct lsm_env lsm_env;             /* Runtime environment */

/* Candidate values for the 3rd argument to lsm_env.xLock() */
#define LSM_LOCK_UNLOCK 0
#define LSM_LOCK_SHARED 1
#define LSM_LOCK_EXCL   2

/*
** Run-time environment used by LSM
*/
struct lsm_env {
  int nByte;                 /* Size of this structure in bytes */
  int iVersion;              /* Version number of this structure */
  /****** file i/o ***********************************************/
  void *pVfsCtx;
  int (*xFullpath)(lsm_env*, const char *, char *, int *);
  int (*xOpen)(lsm_env*, const char *, lsm_file **);
  int (*xRead)(lsm_file *, lsm_i64, void *, int);
  int (*xWrite)(lsm_file *, lsm_i64, void *, int);
  int (*xTruncate)(lsm_file *, lsm_i64);
  int (*xSync)(lsm_file *);
  int (*xSectorSize)(lsm_file *);
  int (*xRemap)(lsm_file *, lsm_i64, void **, lsm_i64*);
  int (*xFileid)(lsm_file *, void *pBuf, int *pnBuf);
  int (*xClose)(lsm_file *);
  int (*xUnlink)(lsm_env*, const char *);
  int (*xLock)(lsm_file*, int, int);
  int (*xShmMap)(lsm_file*, int, int, void **);
  void (*xShmBarrier)(void);
  int (*xShmUnmap)(lsm_file*, int);
  /****** memory allocation ****************************************/
  void *pMemCtx;
  void *(*xMalloc)(lsm_env*, int);            /* malloc(3) function */
  void *(*xRealloc)(lsm_env*, void *, int);   /* realloc(3) function */
  void (*xFree)(lsm_env*, void *);            /* free(3) function */

  sqlite4_size_t (*xSize)(lsm_env*, void *);  /* xSize function */

  /****** mutexes ****************************************************/
  void *pMutexCtx;
  int (*xMutexStatic)(lsm_env*,int,lsm_mutex**); /* Obtain a static mutex */
  int (*xMutexNew)(lsm_env*, lsm_mutex**);       /* Get a new dynamic mutex */
  void (*xMutexDel)(lsm_mutex *);           /* Delete an allocated mutex */
  void (*xMutexEnter)(lsm_mutex *);         /* Grab a mutex */
  int (*xMutexTry)(lsm_mutex *);            /* Attempt to obtain a mutex */

**     A read/write integer parameter. The maximum number of free-list 
**     entries that are stored in a database checkpoint (the others are
**     stored elsewhere in the database).
**
**     There is no reason for an application to configure or query this
**     parameter. It is only present because configuring a small value
**     makes certain parts of the lsm code easier to test.
**
**   LSM_CONFIG_MULTIPLE_PROCESSES
*/
#define LSM_CONFIG_WRITE_BUFFER        1
#define LSM_CONFIG_PAGE_SIZE           2
#define LSM_CONFIG_SAFETY              3
#define LSM_CONFIG_BLOCK_SIZE          4
#define LSM_CONFIG_AUTOWORK            5
#define LSM_CONFIG_LOG_SIZE            6
#define LSM_CONFIG_MMAP                7
#define LSM_CONFIG_USE_LOG             8
#define LSM_CONFIG_NMERGE              9
#define LSM_CONFIG_MAX_FREELIST       10
#define LSM_CONFIG_MULTIPLE_PROCESSES 11

#define LSM_SAFETY_OFF    0
#define LSM_SAFETY_NORMAL 1
#define LSM_SAFETY_FULL   2


/*

  int nTreeLimit;                 /* Configured by LSM_CONFIG_WRITE_BUFFER */
  int nMerge;                     /* Configured by LSM_CONFIG_NMERGE */
  int nLogSz;                     /* Configured by LSM_CONFIG_LOG_SIZE */
  int bUseLog;                    /* Configured by LSM_CONFIG_USE_LOG */
  int nDfltPgsz;                  /* Configured by LSM_CONFIG_PAGE_SIZE */
  int nDfltBlksz;                 /* Configured by LSM_CONFIG_BLOCK_SIZE */
  int nMaxFreelist;               /* Configured by LSM_CONFIG_MAX_FREELIST */
  int bMultiProc;                 /* Configured by L_C_MULTIPLE_PROCESSES */

  /* Sub-system handles */
  FileSystem *pFS;                /* On-disk portion of database */
  Database *pDatabase;            /* Database shared data */

  /* Client transaction context */
  Snapshot *pClient;              /* Client snapshot (non-NULL in read trans) */

/* And to sync the db file */
int lsmFsSyncDb(FileSystem *);

/* Used by lsm_info(ARRAY_STRUCTURE) and lsm_config(MMAP) */
int lsmInfoArrayStructure(lsm_db *pDb, Pgno iFirst, char **pzOut);
int lsmConfigMmap(lsm_db *pDb, int *piParam);

int lsmEnvOpen(lsm_env *, const char *, lsm_file **);
int lsmEnvClose(lsm_env *pEnv, lsm_file *pFile);
int lsmEnvLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int eLock);

int lsmEnvShmMap(lsm_env *, lsm_file *, int, int, void **); 
void lsmEnvShmBarrier(lsm_env *);
void lsmEnvShmUnmap(lsm_env *, lsm_file *, int);

/*
** End of functions from "lsm_file.c".
**************************************************************************/

/* 
** Functions from file "lsm_sorted.c".
*/

int lsmReadlock(lsm_db *, i64 iLsm, i64 iTree);
int lsmReleaseReadlock(lsm_db *);

int lsmLsmInUse(lsm_db *db, i64 iLsmId, int *pbInUse);
int lsmTreeInUse(lsm_db *db, u32 iLsmId, int *pbInUse);
int lsmFreelistAppend(lsm_env *pEnv, Freelist *p, int iBlk, i64 iId);

int lsmDbMultiProc(lsm_db *);


/**************************************************************************
** functions in lsm_str.c
*/
void lsmStringInit(LsmString*, lsm_env *pEnv);
int lsmStringExtend(LsmString*, int);

**
**   In non-mmap() mode, this list is an LRU list of cached pages with nRef==0.
*/
struct FileSystem {
  lsm_db *pDb;                    /* Database handle that owns this object */
  lsm_env *pEnv;                  /* Environment pointer */
  char *zDb;                      /* Database file name */
  char *zLog;                     /* Database file name */
  int nMetasize;                  /* Size of meta pages in bytes */
  int nPagesize;                  /* Database page-size in bytes */
  int nBlocksize;                 /* Database block-size in bytes */

  /* r/w file descriptors for both files. */
  lsm_file *fdDb;                 /* Database file */
  lsm_file *fdLog;                /* Log file */

**     lsmEnvSync()
**     lsmEnvSectorSize()
**     lsmEnvClose()
**     lsmEnvTruncate()
**     lsmEnvUnlink()
**     lsmEnvRemap()
*/
int lsmEnvOpen(lsm_env *pEnv, const char *zFile, lsm_file **ppNew){
  return pEnv->xOpen(pEnv, zFile, ppNew);
}
static int lsmEnvRead(
  lsm_env *pEnv, 
  lsm_file *pFile, 
  lsm_i64 iOff, 
  void *pRead, 

}
static int lsmEnvSync(lsm_env *pEnv, lsm_file *pFile){
  return pEnv->xSync(pFile);
}
static int lsmEnvSectorSize(lsm_env *pEnv, lsm_file *pFile){
  return pEnv->xSectorSize(pFile);
}
int lsmEnvClose(lsm_env *pEnv, lsm_file *pFile){
  return pEnv->xClose(pFile);
}
static int lsmEnvTruncate(lsm_env *pEnv, lsm_file *pFile, lsm_i64 nByte){
  return pEnv->xTruncate(pFile, nByte);
}
static int lsmEnvUnlink(lsm_env *pEnv, const char *zDel){
  return pEnv->xUnlink(pEnv, zDel);
}
static int lsmEnvRemap(
  lsm_env *pEnv, 
  lsm_file *pFile, 
  i64 szMin,
  void **ppMap,
  i64 *pszMap
){
  return pEnv->xRemap(pFile, szMin, ppMap, pszMap);
}

int lsmEnvLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int eLock){
  if( pFile==0 ) return LSM_OK;
  return pEnv->xLock(pFile, iLock, eLock);
}

int lsmEnvShmMap(
  lsm_env *pEnv, 
  lsm_file *pFile, 
  int iChunk, 
  int sz, 
  void **ppOut
){
  return pEnv->xShmMap(pFile, iChunk, sz, ppOut);
}

void lsmEnvShmBarrier(lsm_env *pEnv){
  return pEnv->xShmBarrier();
}

void lsmEnvShmUnmap(lsm_env *pEnv, lsm_file *pFile, int bDel){
  return pEnv->xShmUnmap(pFile, bDel);
}


/*
** Write the contents of string buffer pStr into the log file, starting at
** offset iOff.
*/
int lsmFsWriteLog(FileSystem *pFS, i64 iOff, LsmString *pStr){
  assert( pFS->fdLog );

static lsm_file *fsOpenFile(
  FileSystem *pFS,                /* File system object */
  int bLog,                       /* True for log, false for db */
  int *pRc                        /* IN/OUT: Error code */
){
  lsm_file *pFile = 0;
  if( *pRc==LSM_OK ){





    *pRc = lsmEnvOpen(pFS->pEnv, (bLog ? pFS->zLog : pFS->zDb), &pFile);


  }
  return pFile;
}

/*
** If it is not already open, this function opens the log file. It returns
** LSM_OK if successful (or if the log file was already open) or an LSM

/*
** Open a connection to a database stored within the file-system (the
** "system of files").
*/
int lsmFsOpen(lsm_db *pDb, const char *zDb){
  FileSystem *pFS;
  int rc = LSM_OK;
  int nDb = strlen(zDb);
  int nByte;

  assert( pDb->pFS==0 );
  assert( pDb->pWorker==0 && pDb->pClient==0 );

  nByte = sizeof(FileSystem) + nDb+1 + nDb+4+1;
  pFS = (FileSystem *)lsmMallocZeroRc(pDb->pEnv, nByte, &rc);
  if( pFS ){
    pFS->zDb = (char *)&pFS[1];
    pFS->zLog = &pFS->zDb[nDb+1];
    pFS->nPagesize = LSM_PAGE_SIZE;
    pFS->nBlocksize = LSM_BLOCK_SIZE;
    pFS->nMetasize = 4 * 1024;
    pFS->pDb = pDb;
    pFS->pEnv = pDb->pEnv;

    /* Make a copy of the database and log file names. */
    memcpy(pFS->zDb, zDb, nDb+1);
    memcpy(pFS->zLog, zDb, nDb);
    memcpy(&pFS->zLog[nDb], "-log", 5);

    /* Allocate the hash-table here. At some point, it should be changed
    ** so that it can grow dynamicly. */
    pFS->nCacheMax = 2048;
    pFS->nHash = 4096;
    pFS->apHash = lsmMallocZeroRc(pDb->pEnv, sizeof(Page *) * pFS->nHash, &rc);

      lsmFree(pEnv, pPg);
      pPg = pNext;
    }

    if( pFS->fdDb ) lsmEnvClose(pFS->pEnv, pFS->fdDb );
    if( pFS->fdLog ) lsmEnvClose(pFS->pEnv, pFS->fdLog );


    lsmFree(pEnv, pFS->apHash);
    lsmFree(pEnv, pFS);
  }
}

/*
** Allocate a buffer and populate it with the output of the xFileid() 

  pDb->nLogSz = LSM_DEFAULT_LOG_SIZE;
  pDb->nDfltPgsz = LSM_PAGE_SIZE;
  pDb->nDfltBlksz = LSM_BLOCK_SIZE;
  pDb->nMerge = LSM_DEFAULT_NMERGE;
  pDb->nMaxFreelist = LSM_MAX_FREELIST_ENTRIES;
  pDb->bUseLog = 1;
  pDb->iReader = -1;
  pDb->bMultiProc = 0;
  return LSM_OK;
}

lsm_env *lsm_get_env(lsm_db *pDb){
  assert( pDb->pEnv );
  return pDb->pEnv;
}

      int *piVal = va_arg(ap, int *);
      if( *piVal>=2 && *piVal<=LSM_MAX_FREELIST_ENTRIES ){
        pDb->nMaxFreelist = *piVal;
      }
      *piVal = pDb->nMaxFreelist;
      break;
    }

    case LSM_CONFIG_MULTIPLE_PROCESSES: {
      int *piVal = va_arg(ap, int *);
      if( pDb->pDatabase ){
        /* If lsm_open() has been called, this is a read-only parameter. 
        ** Set the output variable to true if this connection is currently
        ** in multi-process mode.  */
        *piVal = lsmDbMultiProc(pDb);
      }else{
        pDb->bMultiProc = *piVal = (*piVal!=0);
      }
      break;
    }

    default:
      rc = LSM_MISUSE;
      break;
  }

  va_end(ap);

    lsmFree(pEnv, p);
  }else{
    pRet = lsmReallocOrFree(pEnv, p, N);
    if( !pRet ) *pRc = LSM_NOMEM_BKPT;
  }
  return pRet;
}


char *lsmMallocStrdup(lsm_env *pEnv, const char *zIn){
  int nByte;
  char *zRet;
  nByte = strlen(zIn);
  zRet = lsmMalloc(pEnv, nByte+1);
  if( zRet ){

  char *zName;                    /* Canonical path to database file */
  void *pId;                      /* Database id (file inode) */
  int nId;                        /* Size of pId in bytes */
  int nDbRef;                     /* Number of associated lsm_db handles */
  Database *pDbNext;              /* Next Database structure in global list */

  /* Protected by the local mutex (pClientMutex) */
  lsm_file *pFile;                /* Used for locks/shm in multi-proc mode */
  lsm_mutex *pClientMutex;        /* Protects the apShmChunk[] and pConn */
  int nShmChunk;                  /* Number of entries in apShmChunk[] array */
  void **apShmChunk;              /* Array of "shared" memory regions */
  lsm_db *pConn;                  /* List of connections to this db. */
};

/*

** as the only argument.
*/
static void freeDatabase(lsm_env *pEnv, Database *p){
  assert( holdingGlobalMutex(pEnv) );
  if( p ){
    /* Free the mutexes */
    lsmMutexDel(pEnv, p->pClientMutex);

    if( p->pFile ){
      lsmEnvClose(pEnv, p->pFile);
    }

    /* Free the memory allocated for the Database struct itself */
    lsmFree(pEnv, p);
  }
}

static void doDbDisconnect(lsm_db *pDb){

      /* Write a checkpoint to disk. */
      if( rc==LSM_OK ){
        rc = lsmCheckpointWrite(pDb);
      }

      /* If the checkpoint was written successfully, delete the log file */
      if( rc==LSM_OK && pDb->pFS ){
        Database *p = pDb->pDatabase;
        lsmFsCloseAndDeleteLog(pDb->pFS);
        if( p->pFile ) lsmEnvShmUnmap(pDb->pEnv, p->pFile, 1);
      }
    }
  }

  lsmShmLock(pDb, LSM_LOCK_DMS2, LSM_LOCK_UNLOCK, 0);
  lsmShmLock(pDb, LSM_LOCK_DMS1, LSM_LOCK_UNLOCK, 0);
  pDb->pShmhdr = 0;

    /* If no suitable Database object was found, allocate a new one. */
    if( p==0 ){
      int nName = strlen(zName);
      p = (Database *)lsmMallocZeroRc(pEnv, sizeof(Database)+nId+nName+1, &rc);

      /* Allocate the mutex */
      if( rc==LSM_OK ) rc = lsmMutexNew(pEnv, &p->pClientMutex);


      /* If no error has occurred, fill in other fields and link the new 
      ** Database structure into the global list starting at 
      ** gShared.pDatabase. Otherwise, if an error has occurred, free any
      ** resources allocated and return without linking anything new into
      ** the gShared.pDatabase list.  */
      if( rc==LSM_OK ){
        p->zName = (char *)&p[1];
        memcpy((void *)p->zName, zName, nName+1);
        p->pId = (void *)&p->zName[nName+1];
        memcpy(p->pId, pId, nId);
        p->nId = nId;
        p->pDbNext = gShared.pDatabase;
        gShared.pDatabase = p;

      }

      /* If running in multi-process mode, open the shared fd */
      if( rc==LSM_OK && pDb->bMultiProc ){
        rc = lsmEnvOpen(pDb->pEnv, p->zName, &p->pFile);
      }

      if( rc!=LSM_OK ){
        freeDatabase(pEnv, p);
        p = 0;
      }
    }

    if( p ) p->nDbRef++;
    leaveGlobalMutex(pEnv);

      Database **pp;

      /* Remove the Database structure from the linked list. */
      for(pp=&gShared.pDatabase; *pp!=p; pp=&((*pp)->pDbNext));
      *pp = p->pDbNext;

      /* Free the Database object and shared memory buffers. */
      if( p->pFile==0 ){
        for(i=0; i<p->nShmChunk; i++){
          lsmFree(pDb->pEnv, p->apShmChunk[i]);
        }
      }
      lsmFree(pDb->pEnv, p->apShmChunk);
      freeDatabase(pDb->pEnv, p);
    }
    leaveGlobalMutex(pDb->pEnv);
  }
}

      if( rc==LSM_OK ) lsmLogCheckpoint(pDb, iLogoff);
      if( rc==LSM_OK ) lsmTreeEndTransaction(pDb, 1);
      if( rc==LSM_BUSY ) rc = LSM_OK;
      if( pDb->nTransOpen==0 ){
        rc = lsmShmLock(pDb, LSM_LOCK_WRITER, LSM_LOCK_UNLOCK, 0);
      }
    }
    if( rc==LSM_BUSY ) rc = LSM_OK;
  }

  lsmShmLock(pDb, LSM_LOCK_CHECKPOINTER, LSM_LOCK_UNLOCK, 0);
  return rc;
}

int lsmBeginWork(lsm_db *pDb){

  if( db->iReader>=0 ){
    rc = lsmShmLock(db, LSM_LOCK_READER(db->iReader), LSM_LOCK_UNLOCK, 0);
    db->iReader = -1;
  }
  return rc;
}

/*
** This function may only be called after a successful call to
** lsmDbDatabaseConnect(). It returns true if the connection is in
** multi-process mode, or false otherwise.
*/
int lsmDbMultiProc(lsm_db *pDb){
  return (pDb->pDatabase->pFile!=0);
}


/*************************************************************************
**************************************************************************
**************************************************************************
**************************************************************************
**************************************************************************
*************************************************************************/

/*
** Retrieve a pointer to shared-memory chunk iChunk. Chunks are numbered
** starting from 0 (i.e. the header chunk is chunk 0).
*/
int lsmShmChunk(lsm_db *db, int iChunk, void **ppData){
  int rc = LSM_OK;
  void *pRet = 0;
  Database *p = db->pDatabase;
  lsm_env *pEnv = db->pEnv;

  /* Enter the client mutex */
  assert( iChunk>=0 );
  lsmMutexEnter(pEnv, p->pClientMutex);

  if( iChunk>=p->nShmChunk ){
    int nNew = iChunk+1;
    void **apNew;
    apNew = (void **)lsmRealloc(pEnv, p->apShmChunk, sizeof(void*) * nNew);
    if( apNew==0 ){
      rc = LSM_NOMEM_BKPT;
    }else{
      memset(&apNew[p->nShmChunk], 0, sizeof(void*) * (nNew-p->nShmChunk));
      p->apShmChunk = apNew;
      p->nShmChunk = nNew;
    }
  }

  if( rc==LSM_OK && p->apShmChunk[iChunk]==0 ){
    void *pChunk = 0;
    if( p->pFile==0 ){
      /* Single process mode */
      pChunk = lsmMallocZeroRc(pEnv, LSM_SHM_CHUNK_SIZE, &rc);
    }else{
      /* Multi-process mode */
      rc = lsmEnvShmMap(pEnv, p->pFile, iChunk, LSM_SHM_CHUNK_SIZE, &pChunk);
    }
    p->apShmChunk[iChunk] = pChunk;
  }

  if( rc==LSM_OK ){
    pRet = p->apShmChunk[iChunk];
  }

  /* Release the client mutex */
  lsmMutexLeave(pEnv, p->pClientMutex);

  *ppData = pRet; 
  return rc;
}

/*
** Attempt to obtain the lock identified by the iLock and bExcl parameters.
** If successful, return LSM_OK. If the lock cannot be obtained because 
** there exists some other conflicting lock, return LSM_BUSY. If some other
** error occurs, return an LSM error code.
**
** Parameter iLock must be one of LSM_LOCK_WRITER, WORKER or CHECKPOINTER,
** or else a value returned by the LSM_LOCK_READER macro.
*/
int lsmShmLock(
  lsm_db *db, 
  int iLock,
  int eOp,                        /* One of LSM_LOCK_UNLOCK, SHARED or EXCL */
  int bBlock                      /* True for a blocking lock */
){
  lsm_db *pIter;
  const u32 me = (1 << (iLock-1));
  const u32 ms = (1 << (iLock+16-1));
  int rc = LSM_OK;
  Database *p = db->pDatabase;

  assert( iLock>=1 && iLock<=LSM_LOCK_READER(LSM_LOCK_NREADER-1) );
  assert( iLock<=16 );
  assert( eOp==LSM_LOCK_UNLOCK || eOp==LSM_LOCK_SHARED || eOp==LSM_LOCK_EXCL );

  /* Check for a no-op. Proceed only if this is not one of those. */
  if( (eOp==LSM_LOCK_UNLOCK && (db->mLock & (me|ms))!=0)
   || (eOp==LSM_LOCK_SHARED && (db->mLock & (me|ms))!=ms)
   || (eOp==LSM_LOCK_EXCL   && (db->mLock & me)==0)
  ){
    int nExcl = 0;                /* Number of connections holding EXCLUSIVE */
    int nShared = 0;              /* Number of connections holding SHARED */
    lsmMutexEnter(db->pEnv, p->pClientMutex);

    /* Figure out the locks currently held by this process on iLock. */
    for(pIter=p->pConn; pIter; pIter=pIter->pNext){
      if( pIter!=db ){
        if( pIter->mLock & me ){
          nExcl++;
        }else if( pIter->mLock & ms ){
          nShared++;
        }
      }
    }
    assert( nExcl==0 || nExcl==1 );
    assert( nExcl==0 || nShared==0 );
    assert( (db->mLock & me)==0 || (db->mLock & ms)!=0 );

    switch( eOp ){
      case LSM_LOCK_UNLOCK:
        if( nShared<=1 ){
          lsmEnvLock(db->pEnv, p->pFile, iLock, LSM_LOCK_UNLOCK);
        }
        db->mLock &= ~(me|ms);
        break;





      case LSM_LOCK_SHARED:
        if( nExcl && (db->mLock & me)==0 ){
          rc = LSM_BUSY;
        }else{
          if( nShared==0 ){
            rc = lsmEnvLock(db->pEnv, p->pFile, iLock, LSM_LOCK_SHARED);
          }
          db->mLock |= ms;
          db->mLock &= ~me;
        }
        break;


      default:
        assert( eOp==LSM_LOCK_EXCL );
        if( nExcl || nShared>1 || (nShared==1 && (db->mLock & ms)==0) ){
          rc = LSM_BUSY;
        }else{
          rc = lsmEnvLock(db->pEnv, p->pFile, iLock, LSM_LOCK_EXCL);
          db->mLock |= (me|ms);

        }
        break;
    }

    lsmMutexLeave(db->pEnv, p->pClientMutex);
  }

  return rc;
}

#ifdef LSM_DEBUG

int shmLockType(lsm_db *db, int iLock){

** follows:
**
**   (eOp==LSM_LOCK_UNLOCK) -> true if db has no lock on iLock
**   (eOp==LSM_LOCK_SHARED) -> true if db has at least a SHARED lock on iLock.
**   (eOp==LSM_LOCK_EXCL)   -> true if db has an EXCLUSIVE lock on iLock.
*/
int lsmShmAssertLock(lsm_db *db, int iLock, int eOp){


  int ret;
  int eHave;

  assert( iLock>=1 && iLock<=LSM_LOCK_READER(LSM_LOCK_NREADER-1) );
  assert( iLock<=16 );
  assert( eOp==LSM_LOCK_UNLOCK || eOp==LSM_LOCK_SHARED || eOp==LSM_LOCK_EXCL );

    int eHave = shmLockType(db, iLock);
    if( azLock[eHave] ){
      printf("%s(%s on %s)", (bOne?" ":""), azLock[eHave], azName[iLock]);
      bOne = 1;
    }
  }
  printf("\n");
}
void print_all_db_locks(lsm_db *db){
  lsm_db *p;
  for(p=db->pDatabase->pConn; p; p=p->pNext){
    printf("%s connection %p ", ((p==db)?"*":""), p);
    print_db_locks(p);
  }
}
#endif

void lsmShmBarrier(lsm_db *db){

  lsmEnvShmBarrier(db->pEnv);
}

#include <stdio.h>
#include <ctype.h>

#include <unistd.h>
#include <errno.h>

#include <sys/mman.h>

#include "lsmInt.h"

/*
** An open file is an instance of the following object
*/
typedef struct PosixFile PosixFile;
struct PosixFile {
  lsm_env *pEnv;                  /* The run-time environment */
  const char *zName;              /* Full path to file */
  int fd;                         /* The open file descriptor */
  int shmfd;                      /* Shared memory file-descriptor */
  void *pMap;                     /* Pointer to mapping of file fd */
  off_t nMap;                     /* Size of mapping at pMap in bytes */
  int nShm;                       /* Number of entries in array apShm[] */
  void **apShm;                   /* Array of 32K shared memory segments */
};

static int lsm_ioerr(void){ return LSM_IOERR; }

static char *posixShmFile(PosixFile *p){
  char *zShm;
  int nName = strlen(p->zName);
  zShm = (char *)lsmMalloc(p->pEnv, nName+4+1);
  if( zShm ){
    memcpy(zShm, p->zName, nName);
    memcpy(&zShm[nName], "-shm", 5);
  }
  return zShm;
}

static int lsmPosixOsOpen(
  lsm_env *pEnv,
  const char *zFile, 
  lsm_file **ppFile
){
  int rc = LSM_OK;
  PosixFile *p;

  p = lsm_malloc(pEnv, sizeof(PosixFile));
  if( p==0 ){
    rc = LSM_NOMEM;
  }else{
    memset(p, 0, sizeof(PosixFile));
    p->zName = zFile;
    p->pEnv = pEnv;
    p->fd = open(zFile, O_RDWR|O_CREAT, 0644);
    if( p->fd<0 ){
      lsm_free(pEnv, p);
      p = 0;
      rc = lsm_ioerr();
    }

  prc = fstat(p->fd, &buf);
  if( prc!=0 ) return LSM_IOERR_BKPT;

  memcpy(pBuf, &buf.st_dev, sizeof(buf.st_dev));
  memcpy(&(((u8 *)pBuf)[sizeof(buf.st_dev)]), &buf.st_ino, sizeof(buf.st_ino));
  return LSM_OK;
}

static int lsmPosixOsUnlink(lsm_env *pEnv, const char *zFile){
  int prc = unlink(zFile);
  return prc ? LSM_IOERR_BKPT : LSM_OK;
}

int lsmPosixOsLock(lsm_file *pFile, int iLock, int eType){
  int rc = LSM_OK;
  PosixFile *p = (PosixFile *)pFile;
  static const short aType[3] = { F_UNLCK, F_RDLCK, F_WRLCK };
  struct flock lock;

  assert( aType[LSM_LOCK_UNLOCK]==F_UNLCK );
  assert( aType[LSM_LOCK_SHARED]==F_RDLCK );
  assert( aType[LSM_LOCK_EXCL]==F_WRLCK );
  assert( eType>=0 && eType<array_size(aType) );
  assert( iLock>0 && iLock<=16 );

  memset(&lock, 0, sizeof(lock));
  lock.l_whence = SEEK_SET;
  lock.l_len = 1;
  lock.l_type = aType[eType];
  lock.l_start = (4096-iLock);

  if( fcntl(p->fd, F_SETLK, &lock) ){
    int e = errno;
    if( e==EACCES || e==EAGAIN ){
      rc = LSM_BUSY;
    }else{
      rc = LSM_IOERR;
    }
  }

  return LSM_OK;
}

int lsmPosixOsShmMap(lsm_file *pFile, int iChunk, int sz, void **ppShm){
  PosixFile *p = (PosixFile *)pFile;

  *ppShm = 0;
  assert( sz==LSM_SHM_CHUNK_SIZE );
  if( iChunk>=p->nShm ){
    int i;
    void **apNew;
    int nNew = iChunk+1;
    off_t nReq = nNew * LSM_SHM_CHUNK_SIZE;
    struct stat sStat;

    /* If the shared-memory file has not been opened, open it now. */
    if( p->shmfd<=0 ){
      char *zShm = posixShmFile(p);
      if( !zShm ) return LSM_NOMEM_BKPT;
      p->shmfd = open(zShm, O_RDWR|O_CREAT, 0644);
      lsmFree(p->pEnv, zShm);
      if( p->shmfd<0 ){ 
        return LSM_IOERR_BKPT;
      }
    }

    /* If the shared-memory file is not large enough to contain the 
    ** requested chunk, cause it to grow.  */
    if( fstat(p->shmfd, &sStat) ){
      return LSM_IOERR_BKPT;
    }
    if( sStat.st_size<nReq ){
      if( ftruncate(p->shmfd, nReq) ){
        return LSM_IOERR_BKPT;
      }
    }

    apNew = (void **)lsmRealloc(p->pEnv, p->apShm, sizeof(void *) * nNew);
    if( !apNew ) return LSM_NOMEM_BKPT;
    for(i=p->nShm; i<nNew; i++){
      apNew[i] = 0;
    }
    p->apShm = apNew;
    p->nShm = nNew;
  }

  if( p->apShm[iChunk]==0 ){
    p->apShm[iChunk] = mmap(0, LSM_SHM_CHUNK_SIZE, 
        PROT_READ|PROT_WRITE, MAP_SHARED, p->shmfd, iChunk*LSM_SHM_CHUNK_SIZE
    );
    if( p->apShm[iChunk]==0 ) return LSM_IOERR;
  }

  *ppShm = p->apShm[iChunk];
  return LSM_OK;
}

void lsmPosixOsShmBarrier(void){
}

int lsmPosixOsShmUnmap(lsm_file *pFile, int bDelete){
  PosixFile *p = (PosixFile *)pFile;
  if( p->shmfd>0 ){
    int i;
    for(i=0; i<p->nShm; i++){
      if( p->apShm[i] ){
        munmap(p->apShm[i], LSM_SHM_CHUNK_SIZE);
        p->apShm[i] = 0;
      }
    }
    close(p->shmfd);
    p->shmfd = 0;
    if( bDelete ){
      char *zShm = posixShmFile(p);
      if( zShm ) unlink(zShm);
    }
  }
  return LSM_OK;
}


static int lsmPosixOsClose(lsm_file *pFile){
   PosixFile *p = (PosixFile *)pFile;
   lsmPosixOsShmUnmap(pFile, 0);
   if( p->pMap ) munmap(p->pMap, p->nMap);
   close(p->fd);
   lsm_free(p->pEnv, p);
   return LSM_OK;
}






/****************************************************************************
** Memory allocation routines.
*/
#define ROUND8(x) (((x)+7)&~7)
#define BLOCK_HDR_SIZE ROUND8( sizeof(sqlite4_size_t) )

static void *lsmPosixOsMalloc(lsm_env *pEnv, int N){

    lsmPosixOsTruncate,      /* xTruncate */
    lsmPosixOsSync,          /* xSync */
    lsmPosixOsSectorSize,    /* xSectorSize */
    lsmPosixOsRemap,         /* xRemap */
    lsmPosixOsFileid,        /* xFileid */
    lsmPosixOsClose,         /* xClose */
    lsmPosixOsUnlink,        /* xUnlink */
    lsmPosixOsLock,          /* xLock */
    lsmPosixOsShmMap,        /* xShmMap */
    lsmPosixOsShmBarrier,    /* xShmBarrier */
    lsmPosixOsShmUnmap,      /* xShmUnmap */
    /***** memory allocation *********/
    0,                       /* pMemCtx */
    lsmPosixOsMalloc,        /* xMalloc */
    lsmPosixOsRealloc,       /* xRealloc */
    lsmPosixOsFree,          /* xFree */
    lsmPosixOsMSize,         /* xSize */
    /***** mutexes *********************/