自学教程：C++ sqlite3TestTextToPtr函数代码示例

/*** Usage:   btree_update_meta ID METADATA...**** Return meta data*/static int btree_update_meta(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int rc;  int i;  int aMeta[SQLITE_N_BTREE_META];  if( argc!=2+SQLITE_N_BTREE_META ){    char zBuf[30];    sqlite3_snprintf(sizeof(zBuf), zBuf,"%d",SQLITE_N_BTREE_META);    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID METADATA.../" (METADATA is ", zBuf, " integers)", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  for(i=1; i<SQLITE_N_BTREE_META; i++){    if( Tcl_GetInt(interp, argv[i+2], &aMeta[i]) ) return TCL_ERROR;  }  for(i=1; i<SQLITE_N_BTREE_META; i++){    sqlite3BtreeEnter(pBt);    rc = sqlite3BtreeUpdateMeta(pBt, i, aMeta[i]);    sqlite3BtreeLeave(pBt);    if( rc!=SQLITE_OK ){      Tcl_AppendResult(interp, errorName(rc), 0);      return TCL_ERROR;    }  }  return TCL_OK;}

/*** Usage:   page_write PAGE DATA**** Write something into a page.*/static int page_write(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  DbPage *pPage;  char *pData;  int rc;  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE DATA/"", 0);    return TCL_ERROR;  }  pPage = (DbPage *)sqlite3TestTextToPtr(argv[1]);  rc = sqlite3PagerWrite(pPage);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  pData = sqlite3PagerGetData(pPage);  strncpy(pData, argv[2], test_pagesize-1);  pData[test_pagesize-1] = 0;  return TCL_OK;}

/*** Usage:   btree_get_meta ID**** Return meta data*/static int btree_get_meta(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int rc;  int i;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  for(i=0; i<SQLITE_N_BTREE_META; i++){    char zBuf[30];    u32 v;    sqlite3BtreeEnter(pBt);    rc = sqlite3BtreeGetMeta(pBt, i, &v);    sqlite3BtreeLeave(pBt);    if( rc!=SQLITE_OK ){      Tcl_AppendResult(interp, errorName(rc), 0);      return TCL_ERROR;    }    sqlite3_snprintf(sizeof(zBuf), zBuf,"%d",v);    Tcl_AppendElement(interp, zBuf);  }  return TCL_OK;}

/*** Attempt to extract a blob handle (type sqlite3_blob*) from the Tcl** object passed as the second argument. If successful, set *ppBlob to** point to the blob handle and return TCL_OK. Otherwise, store an error** message in the tcl interpreter and return TCL_ERROR. The final value** of *ppBlob is undefined in this case.**** If the object contains a string that begins with "incrblob_", then it** is assumed to be the name of a Tcl channel opened using the [db incrblob] ** command (see tclsqlite.c). Otherwise, it is assumed to be a pointer ** encoded using the ptrToText() routine or similar.*/static int blobHandleFromObj(  Tcl_Interp *interp,   Tcl_Obj *pObj,  sqlite3_blob **ppBlob){  char *z;  int n;  z = Tcl_GetStringFromObj(pObj, &n);  if( n==0 ){    *ppBlob = 0;  }else if( n>9 && 0==memcmp("incrblob_", z, 9) ){    int notUsed;    Tcl_Channel channel;    ClientData instanceData;        channel = Tcl_GetChannel(interp, z, &notUsed);    if( !channel ) return TCL_ERROR;    Tcl_Flush(channel);    Tcl_Seek(channel, 0, SEEK_SET);    instanceData = Tcl_GetChannelInstanceData(channel);    *ppBlob = *((sqlite3_blob **)instanceData);  }else{    *ppBlob = (sqlite3_blob*)sqlite3TestTextToPtr(z);  }  return TCL_OK;}

/*** Usage:   btree_cursor ID TABLENUM WRITEABLE**** Create a new cursor.  Return the ID for the cursor.*/static int btree_cursor(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int iTable;  BtCursor *pCur;  int rc;  int wrFlag;  char zBuf[30];  if( argc!=4 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID TABLENUM WRITEABLE/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  if( Tcl_GetInt(interp, argv[2], &iTable) ) return TCL_ERROR;  if( Tcl_GetBoolean(interp, argv[3], &wrFlag) ) return TCL_ERROR;  pCur = (BtCursor *)ckalloc(sqlite3BtreeCursorSize());  memset(pCur, 0, sqlite3BtreeCursorSize());  sqlite3BtreeEnter(pBt);  rc = sqlite3BtreeCursor(pBt, iTable, wrFlag, 0, pCur);  sqlite3BtreeLeave(pBt);  if( rc ){    ckfree((char *)pCur);    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  sqlite3_snprintf(sizeof(zBuf), zBuf,"%p", pCur);  Tcl_AppendResult(interp, zBuf, 0);  return SQLITE_OK;}

/*** Usage:   btree_first ID**** Move the cursor to the first entry in the table.  Return 0 if the** cursor was left point to something and 1 if the table is empty.*/static int btree_first(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  BtCursor *pCur;  int rc;  int res = 0;  char zBuf[100];  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pCur = sqlite3TestTextToPtr(argv[1]);  sqlite3BtreeEnter(pCur->pBtree);  rc = sqlite3BtreeFirst(pCur, &res);  sqlite3BtreeLeave(pCur->pBtree);  if( rc ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  sqlite3_snprintf(sizeof(zBuf),zBuf,"%d",res);  Tcl_AppendResult(interp, zBuf, 0);  return SQLITE_OK;}

/*** Usage:   btree_close ID**** Close the given database.*/static int btree_close(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int rc;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  rc = sqlite3BtreeClose(pBt);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  nRefSqlite3--;  if( nRefSqlite3==0 ){    sqlite3_mutex_leave(sDb.mutex);    sqlite3_mutex_free(sDb.mutex);    sDb.mutex = 0;    sDb.pVfs = 0;  }  return TCL_OK;}

/*** Usage:   btree_payload_size ID**** Return the number of bytes of payload*/static int btree_payload_size(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  BtCursor *pCur;  int n2;  u64 n1;  char zBuf[50];  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pCur = sqlite3TestTextToPtr(argv[1]);  sqlite3BtreeEnter(pCur->pBtree);  /* The cursor may be in "require-seek" state. If this is the case, the  ** call to BtreeDataSize() will fix it. */  sqlite3BtreeDataSize(pCur, (u32*)&n2);  if( pCur->apPage[pCur->iPage]->intKey ){    n1 = 0;  }else{    sqlite3BtreeKeySize(pCur, (i64*)&n1);  }  sqlite3BtreeLeave(pCur->pBtree);  sqlite3_snprintf(sizeof(zBuf),zBuf, "%d", (int)(n1+n2));  Tcl_AppendResult(interp, zBuf, 0);  return SQLITE_OK;}

/*** Usage:   btree_clear_table ID TABLENUM**** Remove all entries from the given table but keep the table around.*/static int btree_clear_table(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int iTable;  int rc;  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID TABLENUM/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  if( Tcl_GetInt(interp, argv[2], &iTable) ) return TCL_ERROR;  sqlite3BtreeEnter(pBt);  rc = sqlite3BtreeClearTable(pBt, iTable, 0);  sqlite3BtreeLeave(pBt);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  return TCL_OK;}

/*** Usage:   btree_ismemdb ID**** Return true if the B-Tree is currently stored entirely in memory.*/static int btree_ismemdb(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int res;  sqlite3_file *pFile;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  sqlite3_mutex_enter(pBt->db->mutex);  sqlite3BtreeEnter(pBt);  pFile = sqlite3PagerFile(sqlite3BtreePager(pBt));  res = (pFile->pMethods==0);  sqlite3BtreeLeave(pBt);  sqlite3_mutex_leave(pBt->db->mutex);  Tcl_SetObjResult(interp, Tcl_NewBooleanObj(res));  return SQLITE_OK;}

/*** Usage:   btree_create_table ID FLAGS**** Create a new table in the database*/static int btree_create_table(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int rc, iTable, flags;  char zBuf[30];  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID FLAGS/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  if( Tcl_GetInt(interp, argv[2], &flags) ) return TCL_ERROR;  sqlite3BtreeEnter(pBt);  rc = sqlite3BtreeCreateTable(pBt, &iTable, flags);  sqlite3BtreeLeave(pBt);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", iTable);  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

/*** Usage:   pager_stats ID**** Return pager statistics.*/static int pager_stats(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Pager *pPager;  int i, *a;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  a = sqlite3PagerStats(pPager);  for(i=0; i<9; i++){    static char *zName[] = {      "ref", "page", "max", "size", "state", "err",      "hit", "miss", "ovfl",    };    char zBuf[100];    Tcl_AppendElement(interp, zName[i]);    sqlite3_snprintf(sizeof(zBuf),zBuf,"%d",a[i]);    Tcl_AppendElement(interp, zBuf);  }  return TCL_OK;}

/*** Usage:   pager_commit ID**** Commit all changes*/static int pager_commit(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Pager *pPager;  int rc;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  rc = sqlite3PagerCommitPhaseOne(pPager, 0, 0);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  rc = sqlite3PagerCommitPhaseTwo(pPager);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  return TCL_OK;}

/*** Usage: thread_db_put ID DB***/static int tcl_thread_db_put(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  int i;  extern int sqlite3TestMakePointerStr(Tcl_Interp*, char*, void*);  extern void *sqlite3TestTextToPtr(const char *);  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID DB", 0);    return TCL_ERROR;  }  i = parse_thread_id(interp, argv[1]);  if( i<0 ) return TCL_ERROR;  if( !threadset[i].busy ){    Tcl_AppendResult(interp, "no such thread", 0);    return TCL_ERROR;  }  thread_wait(&threadset[i]);  assert( !threadset[i].db );  threadset[i].db = (sqlite3*)sqlite3TestTextToPtr(argv[2]);  return TCL_OK;}

static int page_write(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  DbPage *pPage;  char *pData;  int rc;  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE DATA/"", 0);    return TCL_ERROR;  }  pPage = (DbPage *)sqlite3TestTextToPtr(argv[1]);  rc = sqlite3PagerWrite(pPage);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  pData = sqlite3PagerGetData(pPage);  strncpy(pData, argv[2], test_pagesize-1);  pData[test_pagesize-1] = 0;  return TCL_OK;}

/*** Usage:   page_get ID PGNO**** Return a pointer to a page from the database.*/static int page_get(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Pager *pPager;  char zBuf[100];  DbPage *pPage;  int pgno;  int rc;  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID PGNO/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  if( Tcl_GetInt(interp, argv[2], &pgno) ) return TCL_ERROR;  rc = sqlite3PagerSharedLock(pPager);  if( rc==SQLITE_OK ){    rc = sqlite3PagerGet(pPager, pgno, &pPage);  }  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  sqlite3_snprintf(sizeof(zBuf),zBuf,"%p",pPage);  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

/*** Usage:   btree_close_cursor ID**** Close a cursor opened using btree_cursor.*/static int btree_close_cursor(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  BtCursor *pCur;  Btree *pBt;  int rc;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pCur = sqlite3TestTextToPtr(argv[1]);  pBt = pCur->pBtree;  sqlite3BtreeEnter(pBt);  rc = sqlite3BtreeCloseCursor(pCur);  sqlite3BtreeLeave(pBt);  ckfree((char *)pCur);  if( rc ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  return SQLITE_OK;}

static int pager_commit(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  Pager *pPager;  int rc;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  rc = sqlite3PagerCommitPhaseOne(pPager, 0, 0);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  rc = sqlite3PagerCommitPhaseTwo(pPager);  if( rc!=SQLITE_OK ){    Tcl_AppendResult(interp, errorName(rc), 0);    return TCL_ERROR;  }  return TCL_OK;}

/*** Usage:   page_unref PAGE**** Drop a pointer to a page.*/static int page_unref(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  DbPage *pPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE/"", 0);    return TCL_ERROR;  }  pPage = (DbPage *)sqlite3TestTextToPtr(argv[1]);  sqlite3PagerUnref(pPage);  return TCL_OK;}

static int page_unref(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  DbPage *pPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE/"", 0);    return TCL_ERROR;  }  pPage = (DbPage *)sqlite3TestTextToPtr(argv[1]);  sqlite3PagerUnref(pPage);  return TCL_OK;}

static int page_number(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  char zBuf[100];  DbPage *pPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE/"", 0);    return TCL_ERROR;  }  pPage = (DbPage *)sqlite3TestTextToPtr(argv[1]);  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", sqlite3PagerPagenumber(pPage));  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

/*** Usage:   pager_truncate ID PGNO*/static int pager_truncate(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Pager *pPager;  int pgno;  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID PGNO/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  if( Tcl_GetInt(interp, argv[2], &pgno) ) return TCL_ERROR;  sqlite3PagerTruncateImage(pPager, pgno);  return TCL_OK;}

/*** Usage:   page_number PAGE**** Return the page number for a page.*/static int page_number(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  char zBuf[100];  DbPage *pPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE/"", 0);    return TCL_ERROR;  }  pPage = (DbPage *)sqlite3TestTextToPtr(argv[1]);  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", sqlite3PagerPagenumber(pPage));  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

/*** Usage:   page_read PAGE**** Return the content of a page*/static int SQLITE_TCLAPI page_read(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  char zBuf[100];  DbPage *pPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE/"", 0);    return TCL_ERROR;  }  pPage = sqlite3TestTextToPtr(argv[1]);  memcpy(zBuf, sqlite3PagerGetData(pPage), sizeof(zBuf));  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

static int page_read(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  char zBuf[100];  DbPage *pPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " PAGE/"", 0);    return TCL_ERROR;  }  pPage = sqlite3TestTextToPtr(argv[1]);  memcpy(zBuf, sqlite3PagerGetData(pPage), sizeof(zBuf));  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

static int pager_truncate(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  Pager *pPager;  int pgno;  if( argc!=3 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID PGNO/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  if( Tcl_GetInt(interp, argv[2], &pgno) ) return TCL_ERROR;  sqlite3PagerTruncateImage(pPager, pgno);  return TCL_OK;}

/*** Usage:   btree_pager_stats ID**** Returns pager statistics*/static int btree_pager_stats(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  int i;  int *a;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);   /* Normally in this file, with a b-tree handle opened using the   ** [btree_open] command it is safe to call sqlite3BtreeEnter() directly.  ** But this function is sometimes called with a btree handle obtained  ** from an open SQLite connection (using [btree_from_db]). In this case  ** we need to obtain the mutex for the controlling SQLite handle before  ** it is safe to call sqlite3BtreeEnter().  */  sqlite3_mutex_enter(pBt->db->mutex);  sqlite3BtreeEnter(pBt);  a = sqlite3PagerStats(sqlite3BtreePager(pBt));  for(i=0; i<11; i++){    static char *zName[] = {      "ref", "page", "max", "size", "state", "err",      "hit", "miss", "ovfl", "read", "write"    };    char zBuf[100];    Tcl_AppendElement(interp, zName[i]);    sqlite3_snprintf(sizeof(zBuf), zBuf,"%d",a[i]);    Tcl_AppendElement(interp, zBuf);  }  sqlite3BtreeLeave(pBt);  /* Release the mutex on the SQLite handle that controls this b-tree */  sqlite3_mutex_leave(pBt->db->mutex);  return TCL_OK;}

/*** Usage:   btree_cursor_list ID**** Print information about all cursors to standard output for debugging.*/static int btree_cursor_list(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Btree *pBt;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pBt = sqlite3TestTextToPtr(argv[1]);  sqlite3BtreeEnter(pBt);  sqlite3BtreeCursorList(pBt);  sqlite3BtreeLeave(pBt);  return SQLITE_OK;}

static int pager_pagecount(  void *NotUsed,  Tcl_Interp *interp,      int argc,                const char **argv      ){  Pager *pPager;  char zBuf[100];  int nPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  sqlite3PagerPagecount(pPager, &nPage);  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", nPage);  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}

/*** Usage:   pager_pagecount ID**** Return the size of the database file.*/static int SQLITE_TCLAPI pager_pagecount(  void *NotUsed,  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */  int argc,              /* Number of arguments */  const char **argv      /* Text of each argument */){  Pager *pPager;  char zBuf[100];  int nPage;  if( argc!=2 ){    Tcl_AppendResult(interp, "wrong # args: should be /"", argv[0],       " ID/"", 0);    return TCL_ERROR;  }  pPager = sqlite3TestTextToPtr(argv[1]);  sqlite3PagerPagecount(pPager, &nPage);  sqlite3_snprintf(sizeof(zBuf), zBuf, "%d", nPage);  Tcl_AppendResult(interp, zBuf, 0);  return TCL_OK;}