AryaWu/sqlite
0
1/*2** 2005 May 23 3**4** The author disclaims copyright to this source code. In place of5** a legal notice, here is a blessing:6**7** May you do good and not evil.8** May you find forgiveness for yourself and forgive others.9** May you share freely, never taking more than you give.10**11*************************************************************************12**13** This file contains functions used to access the internal hash tables14** of user defined functions and collation sequences.15*/16 17#include "sqliteInt.h"18 19/*20** Invoke the 'collation needed' callback to request a collation sequence21** in the encoding enc of name zName, length nName.22*/23static void callCollNeeded(sqlite3 *db, int enc, const char *zName){24 assert( !db->xCollNeeded || !db->xCollNeeded16 );25 if( db->xCollNeeded ){26 char *zExternal = sqlite3DbStrDup(db, zName);27 if( !zExternal ) return;28 db->xCollNeeded(db->pCollNeededArg, db, enc, zExternal);29 sqlite3DbFree(db, zExternal);30 }31#ifndef SQLITE_OMIT_UTF1632 if( db->xCollNeeded16 ){33 char const *zExternal;34 sqlite3_value *pTmp = sqlite3ValueNew(db);35 sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF8, SQLITE_STATIC);36 zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);37 if( zExternal ){38 db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);39 }40 sqlite3ValueFree(pTmp);41 }42#endif43}44 45/*46** This routine is called if the collation factory fails to deliver a47** collation function in the best encoding but there may be other versions48** of this collation function (for other text encodings) available. Use one49** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if50** possible.51*/52static int synthCollSeq(sqlite3 *db, CollSeq *pColl){53 CollSeq *pColl2;54 char *z = pColl->zName;55 int i;56 static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };57 for(i=0; i<3; i++){58 pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, 0);59 if( pColl2->xCmp!=0 ){60 memcpy(pColl, pColl2, sizeof(CollSeq));61 pColl->xDel = 0; /* Do not copy the destructor */62 return SQLITE_OK;63 }64 }65 return SQLITE_ERROR;66}67 68/*69** This routine is called on a collation sequence before it is used to70** check that it is defined. An undefined collation sequence exists when71** a database is loaded that contains references to collation sequences72** that have not been defined by sqlite3_create_collation() etc.73**74** If required, this routine calls the 'collation needed' callback to75** request a definition of the collating sequence. If this doesn't work, 76** an equivalent collating sequence that uses a text encoding different77** from the main database is substituted, if one is available.78*/79int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){80 if( pColl && pColl->xCmp==0 ){81 const char *zName = pColl->zName;82 sqlite3 *db = pParse->db;83 CollSeq *p = sqlite3GetCollSeq(pParse, ENC(db), pColl, zName);84 if( !p ){85 return SQLITE_ERROR;86 }87 assert( p==pColl );88 }89 return SQLITE_OK;90}91 92 93 94/*95** Locate and return an entry from the db.aCollSeq hash table. If the entry96** specified by zName and nName is not found and parameter 'create' is97** true, then create a new entry. Otherwise return NULL.98**99** Each pointer stored in the sqlite3.aCollSeq hash table contains an100** array of three CollSeq structures. The first is the collation sequence101** preferred for UTF-8, the second UTF-16le, and the third UTF-16be.102**103** Stored immediately after the three collation sequences is a copy of104** the collation sequence name. A pointer to this string is stored in105** each collation sequence structure.106*/107static CollSeq *findCollSeqEntry(108 sqlite3 *db, /* Database connection */109 const char *zName, /* Name of the collating sequence */110 int create /* Create a new entry if true */111){112 CollSeq *pColl;113 pColl = sqlite3HashFind(&db->aCollSeq, zName);114 115 if( 0==pColl && create ){116 int nName = sqlite3Strlen30(zName) + 1;117 pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName);118 if( pColl ){119 CollSeq *pDel = 0;120 pColl[0].zName = (char*)&pColl[3];121 pColl[0].enc = SQLITE_UTF8;122 pColl[1].zName = (char*)&pColl[3];123 pColl[1].enc = SQLITE_UTF16LE;124 pColl[2].zName = (char*)&pColl[3];125 pColl[2].enc = SQLITE_UTF16BE;126 memcpy(pColl[0].zName, zName, nName);127 pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl);128 129 /* If a malloc() failure occurred in sqlite3HashInsert(), it will 130 ** return the pColl pointer to be deleted (because it wasn't added131 ** to the hash table).132 */133 assert( pDel==0 || pDel==pColl );134 if( pDel!=0 ){135 sqlite3OomFault(db);136 sqlite3DbFree(db, pDel);137 pColl = 0;138 }139 }140 }141 return pColl;142}143 144/*145** Parameter zName points to a UTF-8 encoded string nName bytes long.146** Return the CollSeq* pointer for the collation sequence named zName147** for the encoding 'enc' from the database 'db'.148**149** If the entry specified is not found and 'create' is true, then create a150** new entry. Otherwise return NULL.151**152** A separate function sqlite3LocateCollSeq() is a wrapper around153** this routine. sqlite3LocateCollSeq() invokes the collation factory154** if necessary and generates an error message if the collating sequence155** cannot be found.156**157** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq()158*/159CollSeq *sqlite3FindCollSeq(160 sqlite3 *db, /* Database connection to search */161 u8 enc, /* Desired text encoding */162 const char *zName, /* Name of the collating sequence. Might be NULL */163 int create /* True to create CollSeq if doesn't already exist */164){165 CollSeq *pColl;166 assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );167 assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );168 if( zName ){169 pColl = findCollSeqEntry(db, zName, create);170 if( pColl ) pColl += enc-1;171 }else{172 pColl = db->pDfltColl;173 }174 return pColl;175}176 177/*178** Change the text encoding for a database connection. This means that179** the pDfltColl must change as well.180*/181void sqlite3SetTextEncoding(sqlite3 *db, u8 enc){182 assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );183 db->enc = enc;184 /* EVIDENCE-OF: R-08308-17224 The default collating function for all185 ** strings is BINARY. 186 */187 db->pDfltColl = sqlite3FindCollSeq(db, enc, sqlite3StrBINARY, 0);188 sqlite3ExpirePreparedStatements(db, 1);189}190 191/*192** This function is responsible for invoking the collation factory callback193** or substituting a collation sequence of a different encoding when the194** requested collation sequence is not available in the desired encoding.195** 196** If it is not NULL, then pColl must point to the database native encoding 197** collation sequence with name zName, length nName.198**199** The return value is either the collation sequence to be used in database200** db for collation type name zName, length nName, or NULL, if no collation201** sequence can be found. If no collation is found, leave an error message.202**203** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq()204*/205CollSeq *sqlite3GetCollSeq(206 Parse *pParse, /* Parsing context */207 u8 enc, /* The desired encoding for the collating sequence */208 CollSeq *pColl, /* Collating sequence with native encoding, or NULL */209 const char *zName /* Collating sequence name */210){211 CollSeq *p;212 sqlite3 *db = pParse->db;213 214 p = pColl;215 if( !p ){216 p = sqlite3FindCollSeq(db, enc, zName, 0);217 }218 if( !p || !p->xCmp ){219 /* No collation sequence of this type for this encoding is registered.220 ** Call the collation factory to see if it can supply us with one.221 */222 callCollNeeded(db, enc, zName);223 p = sqlite3FindCollSeq(db, enc, zName, 0);224 }225 if( p && !p->xCmp && synthCollSeq(db, p) ){226 p = 0;227 }228 assert( !p || p->xCmp );229 if( p==0 ){230 sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);231 pParse->rc = SQLITE_ERROR_MISSING_COLLSEQ;232 }233 return p;234}235 236/*237** This function returns the collation sequence for database native text238** encoding identified by the string zName.239**240** If the requested collation sequence is not available, or not available241** in the database native encoding, the collation factory is invoked to242** request it. If the collation factory does not supply such a sequence,243** and the sequence is available in another text encoding, then that is244** returned instead.245**246** If no versions of the requested collations sequence are available, or247** another error occurs, NULL is returned and an error message written into248** pParse.249**250** This routine is a wrapper around sqlite3FindCollSeq(). This routine251** invokes the collation factory if the named collation cannot be found252** and generates an error message.253**254** See also: sqlite3FindCollSeq(), sqlite3GetCollSeq()255*/256CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char *zName){257 sqlite3 *db = pParse->db;258 u8 enc = ENC(db);259 u8 initbusy = db->init.busy;260 CollSeq *pColl;261 262 pColl = sqlite3FindCollSeq(db, enc, zName, initbusy);263 if( !initbusy && (!pColl || !pColl->xCmp) ){264 pColl = sqlite3GetCollSeq(pParse, enc, pColl, zName);265 }266 267 return pColl;268}269 270/* During the search for the best function definition, this procedure271** is called to test how well the function passed as the first argument272** matches the request for a function with nArg arguments in a system273** that uses encoding enc. The value returned indicates how well the274** request is matched. A higher value indicates a better match.275**276** If nArg is -1 that means to only return a match (non-zero) if p->nArg277** is also -1. In other words, we are searching for a function that278** takes a variable number of arguments.279**280** If nArg is -2 that means that we are searching for any function 281** regardless of the number of arguments it uses, so return a positive282** match score for any283**284** The returned value is always between 0 and 6, as follows:285**286** 0: Not a match.287** 1: UTF8/16 conversion required and function takes any number of arguments.288** 2: UTF16 byte order change required and function takes any number of args.289** 3: encoding matches and function takes any number of arguments290** 4: UTF8/16 conversion required - argument count matches exactly291** 5: UTF16 byte order conversion required - argument count matches exactly292** 6: Perfect match: encoding and argument count match exactly.293**294** If nArg==(-2) then any function with a non-null xSFunc is295** a perfect match and any function with xSFunc NULL is296** a non-match.297*/298#define FUNC_PERFECT_MATCH 6 /* The score for a perfect match */299static int matchQuality(300 FuncDef *p, /* The function we are evaluating for match quality */301 int nArg, /* Desired number of arguments. (-1)==any */302 u8 enc /* Desired text encoding */303){304 int match;305 assert( p->nArg>=(-4) && p->nArg!=(-2) );306 assert( nArg>=(-2) );307 308 /* Wrong number of arguments means "no match" */309 if( p->nArg!=nArg ){310 if( nArg==(-2) ) return p->xSFunc==0 ? 0 : FUNC_PERFECT_MATCH;311 if( p->nArg>=0 ) return 0;312 /* Special p->nArg values available to built-in functions only:313 ** -3 1 or more arguments required314 ** -4 2 or more arguments required315 */316 if( p->nArg<(-2) && nArg<(-2-p->nArg) ) return 0;317 }318 319 /* Give a better score to a function with a specific number of arguments320 ** than to function that accepts any number of arguments. */321 if( p->nArg==nArg ){322 match = 4;323 }else{324 match = 1;325 }326 327 /* Bonus points if the text encoding matches */328 if( enc==(p->funcFlags & SQLITE_FUNC_ENCMASK) ){329 match += 2; /* Exact encoding match */330 }else if( (enc & p->funcFlags & 2)!=0 ){331 match += 1; /* Both are UTF16, but with different byte orders */332 }333 334 return match;335}336 337/*338** Search a FuncDefHash for a function with the given name. Return339** a pointer to the matching FuncDef if found, or 0 if there is no match.340*/341FuncDef *sqlite3FunctionSearch(342 int h, /* Hash of the name */343 const char *zFunc /* Name of function */344){345 FuncDef *p;346 for(p=sqlite3BuiltinFunctions.a[h]; p; p=p->u.pHash){347 assert( p->funcFlags & SQLITE_FUNC_BUILTIN );348 if( sqlite3StrICmp(p->zName, zFunc)==0 ){349 return p;350 }351 }352 return 0;353}354 355/*356** Insert a new FuncDef into a FuncDefHash hash table.357*/358void sqlite3InsertBuiltinFuncs(359 FuncDef *aDef, /* List of global functions to be inserted */360 int nDef /* Length of the apDef[] list */361){362 int i;363 for(i=0; i<nDef; i++){364 FuncDef *pOther;365 const char *zName = aDef[i].zName;366 int nName = sqlite3Strlen30(zName);367 int h = SQLITE_FUNC_HASH(zName[0], nName);368 assert( aDef[i].funcFlags & SQLITE_FUNC_BUILTIN );369 pOther = sqlite3FunctionSearch(h, zName);370 if( pOther ){371 assert( pOther!=&aDef[i] && pOther->pNext!=&aDef[i] );372 aDef[i].pNext = pOther->pNext;373 pOther->pNext = &aDef[i];374 }else{375 aDef[i].pNext = 0;376 aDef[i].u.pHash = sqlite3BuiltinFunctions.a[h];377 sqlite3BuiltinFunctions.a[h] = &aDef[i];378 }379 }380}381 382 383 384/*385** Locate a user function given a name, a number of arguments and a flag386** indicating whether the function prefers UTF-16 over UTF-8. Return a387** pointer to the FuncDef structure that defines that function, or return388** NULL if the function does not exist.389**390** If the createFlag argument is true, then a new (blank) FuncDef391** structure is created and liked into the "db" structure if a392** no matching function previously existed.393**394** If nArg is -2, then the first valid function found is returned. A395** function is valid if xSFunc is non-zero. The nArg==(-2)396** case is used to see if zName is a valid function name for some number397** of arguments. If nArg is -2, then createFlag must be 0.398**399** If createFlag is false, then a function with the required name and400** number of arguments may be returned even if the eTextRep flag does not401** match that requested.402*/403FuncDef *sqlite3FindFunction(404 sqlite3 *db, /* An open database */405 const char *zName, /* Name of the function. zero-terminated */406 int nArg, /* Number of arguments. -1 means any number */407 u8 enc, /* Preferred text encoding */408 u8 createFlag /* Create new entry if true and does not otherwise exist */409){410 FuncDef *p; /* Iterator variable */411 FuncDef *pBest = 0; /* Best match found so far */412 int bestScore = 0; /* Score of best match */413 int h; /* Hash value */414 int nName; /* Length of the name */415 416 assert( nArg>=(-2) );417 assert( nArg>=(-1) || createFlag==0 );418 nName = sqlite3Strlen30(zName);419 420 /* First search for a match amongst the application-defined functions.421 */422 p = (FuncDef*)sqlite3HashFind(&db->aFunc, zName);423 while( p ){424 int score = matchQuality(p, nArg, enc);425 if( score>bestScore ){426 pBest = p;427 bestScore = score;428 }429 p = p->pNext;430 }431 432 /* If no match is found, search the built-in functions.433 **434 ** If the DBFLAG_PreferBuiltin flag is set, then search the built-in435 ** functions even if a prior app-defined function was found. And give436 ** priority to built-in functions.437 **438 ** Except, if createFlag is true, that means that we are trying to439 ** install a new function. Whatever FuncDef structure is returned it will440 ** have fields overwritten with new information appropriate for the441 ** new function. But the FuncDefs for built-in functions are read-only.442 ** So we must not search for built-ins when creating a new function.443 */ 444 if( !createFlag && (pBest==0 || (db->mDbFlags & DBFLAG_PreferBuiltin)!=0) ){445 bestScore = 0;446 h = SQLITE_FUNC_HASH(sqlite3UpperToLower[(u8)zName[0]], nName);447 p = sqlite3FunctionSearch(h, zName);448 while( p ){449 int score = matchQuality(p, nArg, enc);450 if( score>bestScore ){451 pBest = p;452 bestScore = score;453 }454 p = p->pNext;455 }456 }457 458 /* If the createFlag parameter is true and the search did not reveal an459 ** exact match for the name, number of arguments and encoding, then add a460 ** new entry to the hash table and return it.461 */462 if( createFlag && bestScore<FUNC_PERFECT_MATCH && 463 (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){464 FuncDef *pOther;465 u8 *z;466 pBest->zName = (const char*)&pBest[1];467 pBest->nArg = (u16)nArg;468 pBest->funcFlags = enc;469 memcpy((char*)&pBest[1], zName, nName+1);470 for(z=(u8*)pBest->zName; *z; z++) *z = sqlite3UpperToLower[*z];471 pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest);472 if( pOther==pBest ){473 sqlite3DbFree(db, pBest);474 sqlite3OomFault(db);475 return 0;476 }else{477 pBest->pNext = pOther;478 }479 }480 481 if( pBest && (pBest->xSFunc || createFlag) ){482 return pBest;483 }484 return 0;485}486 487/*488** Free all resources held by the schema structure. The void* argument points489** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the 490** pointer itself, it just cleans up subsidiary resources (i.e. the contents491** of the schema hash tables).492**493** The Schema.cache_size variable is not cleared.494*/495void sqlite3SchemaClear(void *p){496 Hash temp1;497 Hash temp2;498 HashElem *pElem;499 Schema *pSchema = (Schema *)p;500 sqlite3 xdb;501 502 memset(&xdb, 0, sizeof(xdb));503 temp1 = pSchema->tblHash;504 temp2 = pSchema->trigHash;505 sqlite3HashInit(&pSchema->trigHash);506 sqlite3HashClear(&pSchema->idxHash);507 for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){508 sqlite3DeleteTrigger(&xdb, (Trigger*)sqliteHashData(pElem));509 }510 511 sqlite3HashClear(&temp2);512 sqlite3HashInit(&pSchema->tblHash);513 for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){514 Table *pTab = sqliteHashData(pElem);515 sqlite3DeleteTable(&xdb, pTab);516 }517 sqlite3HashClear(&temp1);518 sqlite3HashClear(&pSchema->fkeyHash);519 pSchema->pSeqTab = 0;520 if( pSchema->schemaFlags & DB_SchemaLoaded ){521 pSchema->iGeneration++;522 }523 pSchema->schemaFlags &= ~(DB_SchemaLoaded|DB_ResetWanted);524}525 526/*527** Find and return the schema associated with a BTree. Create528** a new one if necessary.529*/530Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){531 Schema * p;532 if( pBt ){533 p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);534 }else{535 p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));536 }537 if( !p ){538 sqlite3OomFault(db);539 }else if ( 0==p->file_format ){540 sqlite3HashInit(&p->tblHash);541 sqlite3HashInit(&p->idxHash);542 sqlite3HashInit(&p->trigHash);543 sqlite3HashInit(&p->fkeyHash);544 p->enc = SQLITE_UTF8;545 }546 return p;547}548