root/third_party/sqlite/src/src/attach.c

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DEFINITIONS

This source file includes following definitions.
  1. resolveAttachExpr
  2. attachFunc
  3. detachFunc
  4. codeAttach
  5. sqlite3Detach
  6. sqlite3Attach
  7. sqlite3FixInit
  8. sqlite3FixSrcList
  9. sqlite3FixSelect
  10. sqlite3FixExpr
  11. sqlite3FixExprList
  12. sqlite3FixTriggerStep

/*
** 2003 April 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used to implement the ATTACH and DETACH commands.
*/
#include "sqliteInt.h"

#ifndef SQLITE_OMIT_ATTACH
/*
** Resolve an expression that was part of an ATTACH or DETACH statement. This
** is slightly different from resolving a normal SQL expression, because simple
** identifiers are treated as strings, not possible column names or aliases.
**
** i.e. if the parser sees:
**
**     ATTACH DATABASE abc AS def
**
** it treats the two expressions as literal strings 'abc' and 'def' instead of
** looking for columns of the same name.
**
** This only applies to the root node of pExpr, so the statement:
**
**     ATTACH DATABASE abc||def AS 'db2'
**
** will fail because neither abc or def can be resolved.
*/
static int resolveAttachExpr(NameContext *pName, Expr *pExpr)
{
  int rc = SQLITE_OK;
  if( pExpr ){
    if( pExpr->op!=TK_ID ){
      rc = sqlite3ResolveExprNames(pName, pExpr);
      if( rc==SQLITE_OK && !sqlite3ExprIsConstant(pExpr) ){
        sqlite3ErrorMsg(pName->pParse, "invalid name: \"%s\"", pExpr->u.zToken);
        return SQLITE_ERROR;
      }
    }else{
      pExpr->op = TK_STRING;
    }
  }
  return rc;
}

/*
** An SQL user-function registered to do the work of an ATTACH statement. The
** three arguments to the function come directly from an attach statement:
**
**     ATTACH DATABASE x AS y KEY z
**
**     SELECT sqlite_attach(x, y, z)
**
** If the optional "KEY z" syntax is omitted, an SQL NULL is passed as the
** third argument.
*/
static void attachFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **argv
){
  int i;
  int rc = 0;
  sqlite3 *db = sqlite3_context_db_handle(context);
  const char *zName;
  const char *zFile;
  Db *aNew;
  char *zErrDyn = 0;

  UNUSED_PARAMETER(NotUsed);

  zFile = (const char *)sqlite3_value_text(argv[0]);
  zName = (const char *)sqlite3_value_text(argv[1]);
  if( zFile==0 ) zFile = "";
  if( zName==0 ) zName = "";

  /* Check for the following errors:
  **
  **     * Too many attached databases,
  **     * Transaction currently open
  **     * Specified database name already being used.
  */
  if( db->nDb>=db->aLimit[SQLITE_LIMIT_ATTACHED]+2 ){
    zErrDyn = sqlite3MPrintf(db, "too many attached databases - max %d", 
      db->aLimit[SQLITE_LIMIT_ATTACHED]
    );
    goto attach_error;
  }
  if( !db->autoCommit ){
    zErrDyn = sqlite3MPrintf(db, "cannot ATTACH database within transaction");
    goto attach_error;
  }
  for(i=0; i<db->nDb; i++){
    char *z = db->aDb[i].zName;
    assert( z && zName );
    if( sqlite3StrICmp(z, zName)==0 ){
      zErrDyn = sqlite3MPrintf(db, "database %s is already in use", zName);
      goto attach_error;
    }
  }

  /* Allocate the new entry in the db->aDb[] array and initialise the schema
  ** hash tables.
  */
  if( db->aDb==db->aDbStatic ){
    aNew = sqlite3DbMallocRaw(db, sizeof(db->aDb[0])*3 );
    if( aNew==0 ) return;
    memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
  }else{
    aNew = sqlite3DbRealloc(db, db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
    if( aNew==0 ) return;
  }
  db->aDb = aNew;
  aNew = &db->aDb[db->nDb];
  memset(aNew, 0, sizeof(*aNew));

  /* Open the database file. If the btree is successfully opened, use
  ** it to obtain the database schema. At this point the schema may
  ** or may not be initialised.
  */
  rc = sqlite3BtreeOpen(zFile, db, &aNew->pBt, 0,
                        db->openFlags | SQLITE_OPEN_MAIN_DB);
  db->nDb++;
  if( rc==SQLITE_CONSTRAINT ){
    rc = SQLITE_ERROR;
    zErrDyn = sqlite3MPrintf(db, "database is already attached");
  }else if( rc==SQLITE_OK ){
    Pager *pPager;
    aNew->pSchema = sqlite3SchemaGet(db, aNew->pBt);
    if( !aNew->pSchema ){
      rc = SQLITE_NOMEM;
    }else if( aNew->pSchema->file_format && aNew->pSchema->enc!=ENC(db) ){
      zErrDyn = sqlite3MPrintf(db, 
        "attached databases must use the same text encoding as main database");
      rc = SQLITE_ERROR;
    }
    pPager = sqlite3BtreePager(aNew->pBt);
    sqlite3PagerLockingMode(pPager, db->dfltLockMode);
    sqlite3BtreeSecureDelete(aNew->pBt,
                             sqlite3BtreeSecureDelete(db->aDb[0].pBt,-1) );
  }
  aNew->safety_level = 3;
  aNew->zName = sqlite3DbStrDup(db, zName);
  if( rc==SQLITE_OK && aNew->zName==0 ){
    rc = SQLITE_NOMEM;
  }


#ifdef SQLITE_HAS_CODEC
  if( rc==SQLITE_OK ){
    extern int sqlite3CodecAttach(sqlite3*, int, const void*, int);
    extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
    int nKey;
    char *zKey;
    int t = sqlite3_value_type(argv[2]);
    switch( t ){
      case SQLITE_INTEGER:
      case SQLITE_FLOAT:
        zErrDyn = sqlite3DbStrDup(db, "Invalid key value");
        rc = SQLITE_ERROR;
        break;
        
      case SQLITE_TEXT:
      case SQLITE_BLOB:
        nKey = sqlite3_value_bytes(argv[2]);
        zKey = (char *)sqlite3_value_blob(argv[2]);
        rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
        break;

      case SQLITE_NULL:
        /* No key specified.  Use the key from the main database */
        sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
        if( nKey>0 || sqlite3BtreeGetReserve(db->aDb[0].pBt)>0 ){
          rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
        }
        break;
    }
  }
#endif

  /* If the file was opened successfully, read the schema for the new database.
  ** If this fails, or if opening the file failed, then close the file and 
  ** remove the entry from the db->aDb[] array. i.e. put everything back the way
  ** we found it.
  */
  if( rc==SQLITE_OK ){
    sqlite3BtreeEnterAll(db);
    rc = sqlite3Init(db, &zErrDyn);
    sqlite3BtreeLeaveAll(db);
  }
  if( rc ){
    int iDb = db->nDb - 1;
    assert( iDb>=2 );
    if( db->aDb[iDb].pBt ){
      sqlite3BtreeClose(db->aDb[iDb].pBt);
      db->aDb[iDb].pBt = 0;
      db->aDb[iDb].pSchema = 0;
    }
    sqlite3ResetInternalSchema(db, -1);
    db->nDb = iDb;
    if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
      db->mallocFailed = 1;
      sqlite3DbFree(db, zErrDyn);
      zErrDyn = sqlite3MPrintf(db, "out of memory");
    }else if( zErrDyn==0 ){
      zErrDyn = sqlite3MPrintf(db, "unable to open database: %s", zFile);
    }
    goto attach_error;
  }
  
  return;

attach_error:
  /* Return an error if we get here */
  if( zErrDyn ){
    sqlite3_result_error(context, zErrDyn, -1);
    sqlite3DbFree(db, zErrDyn);
  }
  if( rc ) sqlite3_result_error_code(context, rc);
}

/*
** An SQL user-function registered to do the work of an DETACH statement. The
** three arguments to the function come directly from a detach statement:
**
**     DETACH DATABASE x
**
**     SELECT sqlite_detach(x)
*/
static void detachFunc(
  sqlite3_context *context,
  int NotUsed,
  sqlite3_value **argv
){
  const char *zName = (const char *)sqlite3_value_text(argv[0]);
  sqlite3 *db = sqlite3_context_db_handle(context);
  int i;
  Db *pDb = 0;
  char zErr[128];

  UNUSED_PARAMETER(NotUsed);

  if( zName==0 ) zName = "";
  for(i=0; i<db->nDb; i++){
    pDb = &db->aDb[i];
    if( pDb->pBt==0 ) continue;
    if( sqlite3StrICmp(pDb->zName, zName)==0 ) break;
  }

  if( i>=db->nDb ){
    sqlite3_snprintf(sizeof(zErr),zErr, "no such database: %s", zName);
    goto detach_error;
  }
  if( i<2 ){
    sqlite3_snprintf(sizeof(zErr),zErr, "cannot detach database %s", zName);
    goto detach_error;
  }
  if( !db->autoCommit ){
    sqlite3_snprintf(sizeof(zErr), zErr,
                     "cannot DETACH database within transaction");
    goto detach_error;
  }
  if( sqlite3BtreeIsInReadTrans(pDb->pBt) || sqlite3BtreeIsInBackup(pDb->pBt) ){
    sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
    goto detach_error;
  }

  sqlite3BtreeClose(pDb->pBt);
  pDb->pBt = 0;
  pDb->pSchema = 0;
  sqlite3ResetInternalSchema(db, -1);
  return;

detach_error:
  sqlite3_result_error(context, zErr, -1);
}

/*
** This procedure generates VDBE code for a single invocation of either the
** sqlite_detach() or sqlite_attach() SQL user functions.
*/
static void codeAttach(
  Parse *pParse,       /* The parser context */
  int type,            /* Either SQLITE_ATTACH or SQLITE_DETACH */
  FuncDef const *pFunc,/* FuncDef wrapper for detachFunc() or attachFunc() */
  Expr *pAuthArg,      /* Expression to pass to authorization callback */
  Expr *pFilename,     /* Name of database file */
  Expr *pDbname,       /* Name of the database to use internally */
  Expr *pKey           /* Database key for encryption extension */
){
  int rc;
  NameContext sName;
  Vdbe *v;
  sqlite3* db = pParse->db;
  int regArgs;

  memset(&sName, 0, sizeof(NameContext));
  sName.pParse = pParse;

  if( 
      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pFilename)) ||
      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pDbname)) ||
      SQLITE_OK!=(rc = resolveAttachExpr(&sName, pKey))
  ){
    pParse->nErr++;
    goto attach_end;
  }

#ifndef SQLITE_OMIT_AUTHORIZATION
  if( pAuthArg ){
    char *zAuthArg;
    if( pAuthArg->op==TK_STRING ){
      zAuthArg = pAuthArg->u.zToken;
    }else{
      zAuthArg = 0;
    }
    rc = sqlite3AuthCheck(pParse, type, zAuthArg, 0, 0);
    if(rc!=SQLITE_OK ){
      goto attach_end;
    }
  }
#endif /* SQLITE_OMIT_AUTHORIZATION */


  v = sqlite3GetVdbe(pParse);
  regArgs = sqlite3GetTempRange(pParse, 4);
  sqlite3ExprCode(pParse, pFilename, regArgs);
  sqlite3ExprCode(pParse, pDbname, regArgs+1);
  sqlite3ExprCode(pParse, pKey, regArgs+2);

  assert( v || db->mallocFailed );
  if( v ){
    sqlite3VdbeAddOp3(v, OP_Function, 0, regArgs+3-pFunc->nArg, regArgs+3);
    assert( pFunc->nArg==-1 || (pFunc->nArg&0xff)==pFunc->nArg );
    sqlite3VdbeChangeP5(v, (u8)(pFunc->nArg));
    sqlite3VdbeChangeP4(v, -1, (char *)pFunc, P4_FUNCDEF);

    /* Code an OP_Expire. For an ATTACH statement, set P1 to true (expire this
    ** statement only). For DETACH, set it to false (expire all existing
    ** statements).
    */
    sqlite3VdbeAddOp1(v, OP_Expire, (type==SQLITE_ATTACH));
  }
  
attach_end:
  sqlite3ExprDelete(db, pFilename);
  sqlite3ExprDelete(db, pDbname);
  sqlite3ExprDelete(db, pKey);
}

/*
** Called by the parser to compile a DETACH statement.
**
**     DETACH pDbname
*/
void sqlite3Detach(Parse *pParse, Expr *pDbname){
  static const FuncDef detach_func = {
    1,                /* nArg */
    SQLITE_UTF8,      /* iPrefEnc */
    0,                /* flags */
    0,                /* pUserData */
    0,                /* pNext */
    detachFunc,       /* xFunc */
    0,                /* xStep */
    0,                /* xFinalize */
    "sqlite_detach",  /* zName */
    0,                /* pHash */
    0                 /* pDestructor */
  };
  codeAttach(pParse, SQLITE_DETACH, &detach_func, pDbname, 0, 0, pDbname);
}

/*
** Called by the parser to compile an ATTACH statement.
**
**     ATTACH p AS pDbname KEY pKey
*/
void sqlite3Attach(Parse *pParse, Expr *p, Expr *pDbname, Expr *pKey){
  static const FuncDef attach_func = {
    3,                /* nArg */
    SQLITE_UTF8,      /* iPrefEnc */
    0,                /* flags */
    0,                /* pUserData */
    0,                /* pNext */
    attachFunc,       /* xFunc */
    0,                /* xStep */
    0,                /* xFinalize */
    "sqlite_attach",  /* zName */
    0,                /* pHash */
    0                 /* pDestructor */
  };
  codeAttach(pParse, SQLITE_ATTACH, &attach_func, p, p, pDbname, pKey);
}
#endif /* SQLITE_OMIT_ATTACH */

/*
** Initialize a DbFixer structure.  This routine must be called prior
** to passing the structure to one of the sqliteFixAAAA() routines below.
**
** The return value indicates whether or not fixation is required.  TRUE
** means we do need to fix the database references, FALSE means we do not.
*/
int sqlite3FixInit(
  DbFixer *pFix,      /* The fixer to be initialized */
  Parse *pParse,      /* Error messages will be written here */
  int iDb,            /* This is the database that must be used */
  const char *zType,  /* "view", "trigger", or "index" */
  const Token *pName  /* Name of the view, trigger, or index */
){
  sqlite3 *db;

  if( NEVER(iDb<0) || iDb==1 ) return 0;
  db = pParse->db;
  assert( db->nDb>iDb );
  pFix->pParse = pParse;
  pFix->zDb = db->aDb[iDb].zName;
  pFix->zType = zType;
  pFix->pName = pName;
  return 1;
}

/*
** The following set of routines walk through the parse tree and assign
** a specific database to all table references where the database name
** was left unspecified in the original SQL statement.  The pFix structure
** must have been initialized by a prior call to sqlite3FixInit().
**
** These routines are used to make sure that an index, trigger, or
** view in one database does not refer to objects in a different database.
** (Exception: indices, triggers, and views in the TEMP database are
** allowed to refer to anything.)  If a reference is explicitly made
** to an object in a different database, an error message is added to
** pParse->zErrMsg and these routines return non-zero.  If everything
** checks out, these routines return 0.
*/
int sqlite3FixSrcList(
  DbFixer *pFix,       /* Context of the fixation */
  SrcList *pList       /* The Source list to check and modify */
){
  int i;
  const char *zDb;
  struct SrcList_item *pItem;

  if( NEVER(pList==0) ) return 0;
  zDb = pFix->zDb;
  for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
    if( pItem->zDatabase==0 ){
      pItem->zDatabase = sqlite3DbStrDup(pFix->pParse->db, zDb);
    }else if( sqlite3StrICmp(pItem->zDatabase,zDb)!=0 ){
      sqlite3ErrorMsg(pFix->pParse,
         "%s %T cannot reference objects in database %s",
         pFix->zType, pFix->pName, pItem->zDatabase);
      return 1;
    }
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
    if( sqlite3FixSelect(pFix, pItem->pSelect) ) return 1;
    if( sqlite3FixExpr(pFix, pItem->pOn) ) return 1;
#endif
  }
  return 0;
}
#if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
int sqlite3FixSelect(
  DbFixer *pFix,       /* Context of the fixation */
  Select *pSelect      /* The SELECT statement to be fixed to one database */
){
  while( pSelect ){
    if( sqlite3FixExprList(pFix, pSelect->pEList) ){
      return 1;
    }
    if( sqlite3FixSrcList(pFix, pSelect->pSrc) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pWhere) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pSelect->pHaving) ){
      return 1;
    }
    pSelect = pSelect->pPrior;
  }
  return 0;
}
int sqlite3FixExpr(
  DbFixer *pFix,     /* Context of the fixation */
  Expr *pExpr        /* The expression to be fixed to one database */
){
  while( pExpr ){
    if( ExprHasAnyProperty(pExpr, EP_TokenOnly) ) break;
    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
      if( sqlite3FixSelect(pFix, pExpr->x.pSelect) ) return 1;
    }else{
      if( sqlite3FixExprList(pFix, pExpr->x.pList) ) return 1;
    }
    if( sqlite3FixExpr(pFix, pExpr->pRight) ){
      return 1;
    }
    pExpr = pExpr->pLeft;
  }
  return 0;
}
int sqlite3FixExprList(
  DbFixer *pFix,     /* Context of the fixation */
  ExprList *pList    /* The expression to be fixed to one database */
){
  int i;
  struct ExprList_item *pItem;
  if( pList==0 ) return 0;
  for(i=0, pItem=pList->a; i<pList->nExpr; i++, pItem++){
    if( sqlite3FixExpr(pFix, pItem->pExpr) ){
      return 1;
    }
  }
  return 0;
}
#endif

#ifndef SQLITE_OMIT_TRIGGER
int sqlite3FixTriggerStep(
  DbFixer *pFix,     /* Context of the fixation */
  TriggerStep *pStep /* The trigger step be fixed to one database */
){
  while( pStep ){
    if( sqlite3FixSelect(pFix, pStep->pSelect) ){
      return 1;
    }
    if( sqlite3FixExpr(pFix, pStep->pWhere) ){
      return 1;
    }
    if( sqlite3FixExprList(pFix, pStep->pExprList) ){
      return 1;
    }
    pStep = pStep->pNext;
  }
  return 0;
}
#endif

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