sl@0: /*
sl@0: ** 2005 May 23 
sl@0: **
sl@0: ** The author disclaims copyright to this source code.  In place of
sl@0: ** a legal notice, here is a blessing:
sl@0: **
sl@0: **    May you do good and not evil.
sl@0: **    May you find forgiveness for yourself and forgive others.
sl@0: **    May you share freely, never taking more than you give.
sl@0: **
sl@0: *************************************************************************
sl@0: **
sl@0: ** This file contains functions used to access the internal hash tables
sl@0: ** of user defined functions and collation sequences.
sl@0: **
sl@0: ** $Id: callback.c,v 1.26 2008/07/28 19:34:53 drh Exp $
sl@0: */
sl@0: 
sl@0: #include "sqliteInt.h"
sl@0: 
sl@0: /*
sl@0: ** Invoke the 'collation needed' callback to request a collation sequence
sl@0: ** in the database text encoding of name zName, length nName.
sl@0: ** If the collation sequence
sl@0: */
sl@0: static void callCollNeeded(sqlite3 *db, const char *zName, int nName){
sl@0:   assert( !db->xCollNeeded || !db->xCollNeeded16 );
sl@0:   if( nName<0 ) nName = sqlite3Strlen(db, zName);
sl@0:   if( db->xCollNeeded ){
sl@0:     char *zExternal = sqlite3DbStrNDup(db, zName, nName);
sl@0:     if( !zExternal ) return;
sl@0:     db->xCollNeeded(db->pCollNeededArg, db, (int)ENC(db), zExternal);
sl@0:     sqlite3DbFree(db, zExternal);
sl@0:   }
sl@0: #ifndef SQLITE_OMIT_UTF16
sl@0:   if( db->xCollNeeded16 ){
sl@0:     char const *zExternal;
sl@0:     sqlite3_value *pTmp = sqlite3ValueNew(db);
sl@0:     sqlite3ValueSetStr(pTmp, nName, zName, SQLITE_UTF8, SQLITE_STATIC);
sl@0:     zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);
sl@0:     if( zExternal ){
sl@0:       db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);
sl@0:     }
sl@0:     sqlite3ValueFree(pTmp);
sl@0:   }
sl@0: #endif
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This routine is called if the collation factory fails to deliver a
sl@0: ** collation function in the best encoding but there may be other versions
sl@0: ** of this collation function (for other text encodings) available. Use one
sl@0: ** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if
sl@0: ** possible.
sl@0: */
sl@0: static int synthCollSeq(sqlite3 *db, CollSeq *pColl){
sl@0:   CollSeq *pColl2;
sl@0:   char *z = pColl->zName;
sl@0:   int n = strlen(z);
sl@0:   int i;
sl@0:   static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };
sl@0:   for(i=0; i<3; i++){
sl@0:     pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, n, 0);
sl@0:     if( pColl2->xCmp!=0 ){
sl@0:       memcpy(pColl, pColl2, sizeof(CollSeq));
sl@0:       pColl->xDel = 0;         /* Do not copy the destructor */
sl@0:       return SQLITE_OK;
sl@0:     }
sl@0:   }
sl@0:   return SQLITE_ERROR;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This function is responsible for invoking the collation factory callback
sl@0: ** or substituting a collation sequence of a different encoding when the
sl@0: ** requested collation sequence is not available in the database native
sl@0: ** encoding.
sl@0: ** 
sl@0: ** If it is not NULL, then pColl must point to the database native encoding 
sl@0: ** collation sequence with name zName, length nName.
sl@0: **
sl@0: ** The return value is either the collation sequence to be used in database
sl@0: ** db for collation type name zName, length nName, or NULL, if no collation
sl@0: ** sequence can be found.
sl@0: */
sl@0: CollSeq *sqlite3GetCollSeq(
sl@0:   sqlite3* db, 
sl@0:   CollSeq *pColl, 
sl@0:   const char *zName, 
sl@0:   int nName
sl@0: ){
sl@0:   CollSeq *p;
sl@0: 
sl@0:   p = pColl;
sl@0:   if( !p ){
sl@0:     p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);
sl@0:   }
sl@0:   if( !p || !p->xCmp ){
sl@0:     /* No collation sequence of this type for this encoding is registered.
sl@0:     ** Call the collation factory to see if it can supply us with one.
sl@0:     */
sl@0:     callCollNeeded(db, zName, nName);
sl@0:     p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);
sl@0:   }
sl@0:   if( p && !p->xCmp && synthCollSeq(db, p) ){
sl@0:     p = 0;
sl@0:   }
sl@0:   assert( !p || p->xCmp );
sl@0:   return p;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** This routine is called on a collation sequence before it is used to
sl@0: ** check that it is defined. An undefined collation sequence exists when
sl@0: ** a database is loaded that contains references to collation sequences
sl@0: ** that have not been defined by sqlite3_create_collation() etc.
sl@0: **
sl@0: ** If required, this routine calls the 'collation needed' callback to
sl@0: ** request a definition of the collating sequence. If this doesn't work, 
sl@0: ** an equivalent collating sequence that uses a text encoding different
sl@0: ** from the main database is substituted, if one is available.
sl@0: */
sl@0: int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){
sl@0:   if( pColl ){
sl@0:     const char *zName = pColl->zName;
sl@0:     CollSeq *p = sqlite3GetCollSeq(pParse->db, pColl, zName, -1);
sl@0:     if( !p ){
sl@0:       if( pParse->nErr==0 ){
sl@0:         sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);
sl@0:       }
sl@0:       pParse->nErr++;
sl@0:       return SQLITE_ERROR;
sl@0:     }
sl@0:     assert( p==pColl );
sl@0:   }
sl@0:   return SQLITE_OK;
sl@0: }
sl@0: 
sl@0: 
sl@0: 
sl@0: /*
sl@0: ** Locate and return an entry from the db.aCollSeq hash table. If the entry
sl@0: ** specified by zName and nName is not found and parameter 'create' is
sl@0: ** true, then create a new entry. Otherwise return NULL.
sl@0: **
sl@0: ** Each pointer stored in the sqlite3.aCollSeq hash table contains an
sl@0: ** array of three CollSeq structures. The first is the collation sequence
sl@0: ** prefferred for UTF-8, the second UTF-16le, and the third UTF-16be.
sl@0: **
sl@0: ** Stored immediately after the three collation sequences is a copy of
sl@0: ** the collation sequence name. A pointer to this string is stored in
sl@0: ** each collation sequence structure.
sl@0: */
sl@0: static CollSeq *findCollSeqEntry(
sl@0:   sqlite3 *db,
sl@0:   const char *zName,
sl@0:   int nName,
sl@0:   int create
sl@0: ){
sl@0:   CollSeq *pColl;
sl@0:   if( nName<0 ) nName = sqlite3Strlen(db, zName);
sl@0:   pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);
sl@0: 
sl@0:   if( 0==pColl && create ){
sl@0:     pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1 );
sl@0:     if( pColl ){
sl@0:       CollSeq *pDel = 0;
sl@0:       pColl[0].zName = (char*)&pColl[3];
sl@0:       pColl[0].enc = SQLITE_UTF8;
sl@0:       pColl[1].zName = (char*)&pColl[3];
sl@0:       pColl[1].enc = SQLITE_UTF16LE;
sl@0:       pColl[2].zName = (char*)&pColl[3];
sl@0:       pColl[2].enc = SQLITE_UTF16BE;
sl@0:       memcpy(pColl[0].zName, zName, nName);
sl@0:       pColl[0].zName[nName] = 0;
sl@0:       pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl);
sl@0: 
sl@0:       /* If a malloc() failure occured in sqlite3HashInsert(), it will 
sl@0:       ** return the pColl pointer to be deleted (because it wasn't added
sl@0:       ** to the hash table).
sl@0:       */
sl@0:       assert( pDel==0 || pDel==pColl );
sl@0:       if( pDel!=0 ){
sl@0:         db->mallocFailed = 1;
sl@0:         sqlite3DbFree(db, pDel);
sl@0:         pColl = 0;
sl@0:       }
sl@0:     }
sl@0:   }
sl@0:   return pColl;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Parameter zName points to a UTF-8 encoded string nName bytes long.
sl@0: ** Return the CollSeq* pointer for the collation sequence named zName
sl@0: ** for the encoding 'enc' from the database 'db'.
sl@0: **
sl@0: ** If the entry specified is not found and 'create' is true, then create a
sl@0: ** new entry.  Otherwise return NULL.
sl@0: **
sl@0: ** A separate function sqlite3LocateCollSeq() is a wrapper around
sl@0: ** this routine.  sqlite3LocateCollSeq() invokes the collation factory
sl@0: ** if necessary and generates an error message if the collating sequence
sl@0: ** cannot be found.
sl@0: */
sl@0: CollSeq *sqlite3FindCollSeq(
sl@0:   sqlite3 *db,
sl@0:   u8 enc,
sl@0:   const char *zName,
sl@0:   int nName,
sl@0:   int create
sl@0: ){
sl@0:   CollSeq *pColl;
sl@0:   if( zName ){
sl@0:     pColl = findCollSeqEntry(db, zName, nName, create);
sl@0:   }else{
sl@0:     pColl = db->pDfltColl;
sl@0:   }
sl@0:   assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
sl@0:   /*assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );*/
sl@0:   if( pColl ) pColl += enc-1;
sl@0:   return pColl;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Locate a user function given a name, a number of arguments and a flag
sl@0: ** indicating whether the function prefers UTF-16 over UTF-8.  Return a
sl@0: ** pointer to the FuncDef structure that defines that function, or return
sl@0: ** NULL if the function does not exist.
sl@0: **
sl@0: ** If the createFlag argument is true, then a new (blank) FuncDef
sl@0: ** structure is created and liked into the "db" structure if a
sl@0: ** no matching function previously existed.  When createFlag is true
sl@0: ** and the nArg parameter is -1, then only a function that accepts
sl@0: ** any number of arguments will be returned.
sl@0: **
sl@0: ** If createFlag is false and nArg is -1, then the first valid
sl@0: ** function found is returned.  A function is valid if either xFunc
sl@0: ** or xStep is non-zero.
sl@0: **
sl@0: ** If createFlag is false, then a function with the required name and
sl@0: ** number of arguments may be returned even if the eTextRep flag does not
sl@0: ** match that requested.
sl@0: */
sl@0: FuncDef *sqlite3FindFunction(
sl@0:   sqlite3 *db,       /* An open database */
sl@0:   const char *zName, /* Name of the function.  Not null-terminated */
sl@0:   int nName,         /* Number of characters in the name */
sl@0:   int nArg,          /* Number of arguments.  -1 means any number */
sl@0:   u8 enc,            /* Preferred text encoding */
sl@0:   int createFlag     /* Create new entry if true and does not otherwise exist */
sl@0: ){
sl@0:   FuncDef *p;         /* Iterator variable */
sl@0:   FuncDef *pFirst;    /* First function with this name */
sl@0:   FuncDef *pBest = 0; /* Best match found so far */
sl@0:   int bestmatch = 0;  
sl@0: 
sl@0: 
sl@0:   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
sl@0:   if( nArg<-1 ) nArg = -1;
sl@0: 
sl@0:   pFirst = (FuncDef*)sqlite3HashFind(&db->aFunc, zName, nName);
sl@0:   for(p=pFirst; p; p=p->pNext){
sl@0:     /* During the search for the best function definition, bestmatch is set
sl@0:     ** as follows to indicate the quality of the match with the definition
sl@0:     ** pointed to by pBest:
sl@0:     **
sl@0:     ** 0: pBest is NULL. No match has been found.
sl@0:     ** 1: A variable arguments function that prefers UTF-8 when a UTF-16
sl@0:     **    encoding is requested, or vice versa.
sl@0:     ** 2: A variable arguments function that uses UTF-16BE when UTF-16LE is
sl@0:     **    requested, or vice versa.
sl@0:     ** 3: A variable arguments function using the same text encoding.
sl@0:     ** 4: A function with the exact number of arguments requested that
sl@0:     **    prefers UTF-8 when a UTF-16 encoding is requested, or vice versa.
sl@0:     ** 5: A function with the exact number of arguments requested that
sl@0:     **    prefers UTF-16LE when UTF-16BE is requested, or vice versa.
sl@0:     ** 6: An exact match.
sl@0:     **
sl@0:     ** A larger value of 'matchqual' indicates a more desirable match.
sl@0:     */
sl@0:     if( p->nArg==-1 || p->nArg==nArg || nArg==-1 ){
sl@0:       int match = 1;          /* Quality of this match */
sl@0:       if( p->nArg==nArg || nArg==-1 ){
sl@0:         match = 4;
sl@0:       }
sl@0:       if( enc==p->iPrefEnc ){
sl@0:         match += 2;
sl@0:       }
sl@0:       else if( (enc==SQLITE_UTF16LE && p->iPrefEnc==SQLITE_UTF16BE) ||
sl@0:                (enc==SQLITE_UTF16BE && p->iPrefEnc==SQLITE_UTF16LE) ){
sl@0:         match += 1;
sl@0:       }
sl@0: 
sl@0:       if( match>bestmatch ){
sl@0:         pBest = p;
sl@0:         bestmatch = match;
sl@0:       }
sl@0:     }
sl@0:   }
sl@0: 
sl@0:   /* If the createFlag parameter is true, and the seach did not reveal an
sl@0:   ** exact match for the name, number of arguments and encoding, then add a
sl@0:   ** new entry to the hash table and return it.
sl@0:   */
sl@0:   if( createFlag && bestmatch<6 && 
sl@0:       (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName))!=0 ){
sl@0:     pBest->nArg = nArg;
sl@0:     pBest->pNext = pFirst;
sl@0:     pBest->iPrefEnc = enc;
sl@0:     memcpy(pBest->zName, zName, nName);
sl@0:     pBest->zName[nName] = 0;
sl@0:     if( pBest==sqlite3HashInsert(&db->aFunc,pBest->zName,nName,(void*)pBest) ){
sl@0:       db->mallocFailed = 1;
sl@0:       sqlite3DbFree(db, pBest);
sl@0:       return 0;
sl@0:     }
sl@0:   }
sl@0: 
sl@0:   if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){
sl@0:     return pBest;
sl@0:   }
sl@0:   return 0;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Free all resources held by the schema structure. The void* argument points
sl@0: ** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the 
sl@0: ** pointer itself, it just cleans up subsiduary resources (i.e. the contents
sl@0: ** of the schema hash tables).
sl@0: **
sl@0: ** The Schema.cache_size variable is not cleared.
sl@0: */
sl@0: void sqlite3SchemaFree(void *p){
sl@0:   Hash temp1;
sl@0:   Hash temp2;
sl@0:   HashElem *pElem;
sl@0:   Schema *pSchema = (Schema *)p;
sl@0: 
sl@0:   temp1 = pSchema->tblHash;
sl@0:   temp2 = pSchema->trigHash;
sl@0:   sqlite3HashInit(&pSchema->trigHash, SQLITE_HASH_STRING, 0);
sl@0:   sqlite3HashClear(&pSchema->aFKey);
sl@0:   sqlite3HashClear(&pSchema->idxHash);
sl@0:   for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
sl@0:     sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));
sl@0:   }
sl@0:   sqlite3HashClear(&temp2);
sl@0:   sqlite3HashInit(&pSchema->tblHash, SQLITE_HASH_STRING, 0);
sl@0:   for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
sl@0:     Table *pTab = sqliteHashData(pElem);
sl@0:     sqlite3DeleteTable(pTab);
sl@0:   }
sl@0:   sqlite3HashClear(&temp1);
sl@0:   pSchema->pSeqTab = 0;
sl@0:   pSchema->flags &= ~DB_SchemaLoaded;
sl@0: }
sl@0: 
sl@0: /*
sl@0: ** Find and return the schema associated with a BTree.  Create
sl@0: ** a new one if necessary.
sl@0: */
sl@0: Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
sl@0:   Schema * p;
sl@0:   if( pBt ){
sl@0:     p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaFree);
sl@0:   }else{
sl@0:     p = (Schema *)sqlite3MallocZero(sizeof(Schema));
sl@0:   }
sl@0:   if( !p ){
sl@0:     db->mallocFailed = 1;
sl@0:   }else if ( 0==p->file_format ){
sl@0:     sqlite3HashInit(&p->tblHash, SQLITE_HASH_STRING, 0);
sl@0:     sqlite3HashInit(&p->idxHash, SQLITE_HASH_STRING, 0);
sl@0:     sqlite3HashInit(&p->trigHash, SQLITE_HASH_STRING, 0);
sl@0:     sqlite3HashInit(&p->aFKey, SQLITE_HASH_STRING, 1);
sl@0:     p->enc = SQLITE_UTF8;
sl@0:   }
sl@0:   return p;
sl@0: }