1/* 2** 2005 May 23 3** 4** The author disclaims copyright to this source code. In place of 5** 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 tables 14** 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 sequence 21** 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_UTF16 32 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#endif 43} 44 45/* 46** This routine is called if the collation factory fails to deliver a 47** collation function in the best encoding but there may be other versions 48** of this collation function (for other text encodings) available. Use one 49** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if 50** 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 function is responsible for invoking the collation factory callback 70** or substituting a collation sequence of a different encoding when the 71** requested collation sequence is not available in the desired encoding. 72** 73** If it is not NULL, then pColl must point to the database native encoding 74** collation sequence with name zName, length nName. 75** 76** The return value is either the collation sequence to be used in database 77** db for collation type name zName, length nName, or NULL, if no collation 78** sequence can be found. 79** 80** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq() 81*/ 82CollSeq *sqlite3GetCollSeq( 83 sqlite3* db, /* The database connection */ 84 u8 enc, /* The desired encoding for the collating sequence */ 85 CollSeq *pColl, /* Collating sequence with native encoding, or NULL */ 86 const char *zName /* Collating sequence name */ 87){ 88 CollSeq *p; 89 90 p = pColl; 91 if( !p ){ 92 p = sqlite3FindCollSeq(db, enc, zName, 0); 93 } 94 if( !p || !p->xCmp ){ 95 /* No collation sequence of this type for this encoding is registered. 96 ** Call the collation factory to see if it can supply us with one. 97 */ 98 callCollNeeded(db, enc, zName); 99 p = sqlite3FindCollSeq(db, enc, zName, 0); 100 } 101 if( p && !p->xCmp && synthCollSeq(db, p) ){ 102 p = 0; 103 } 104 assert( !p || p->xCmp ); 105 return p; 106} 107 108/* 109** This routine is called on a collation sequence before it is used to 110** check that it is defined. An undefined collation sequence exists when 111** a database is loaded that contains references to collation sequences 112** that have not been defined by sqlite3_create_collation() etc. 113** 114** If required, this routine calls the 'collation needed' callback to 115** request a definition of the collating sequence. If this doesn't work, 116** an equivalent collating sequence that uses a text encoding different 117** from the main database is substituted, if one is available. 118*/ 119int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){ 120 if( pColl ){ 121 const char *zName = pColl->zName; 122 sqlite3 *db = pParse->db; 123 CollSeq *p = sqlite3GetCollSeq(db, ENC(db), pColl, zName); 124 if( !p ){ 125 sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName); 126 pParse->nErr++; 127 return SQLITE_ERROR; 128 } 129 assert( p==pColl ); 130 } 131 return SQLITE_OK; 132} 133 134 135 136/* 137** Locate and return an entry from the db.aCollSeq hash table. If the entry 138** specified by zName and nName is not found and parameter 'create' is 139** true, then create a new entry. Otherwise return NULL. 140** 141** Each pointer stored in the sqlite3.aCollSeq hash table contains an 142** array of three CollSeq structures. The first is the collation sequence 143** prefferred for UTF-8, the second UTF-16le, and the third UTF-16be. 144** 145** Stored immediately after the three collation sequences is a copy of 146** the collation sequence name. A pointer to this string is stored in 147** each collation sequence structure. 148*/ 149static CollSeq *findCollSeqEntry( 150 sqlite3 *db, /* Database connection */ 151 const char *zName, /* Name of the collating sequence */ 152 int create /* Create a new entry if true */ 153){ 154 CollSeq *pColl; 155 int nName = sqlite3Strlen30(zName); 156 pColl = sqlite3HashFind(&db->aCollSeq, zName, nName); 157 158 if( 0==pColl && create ){ 159 pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1 ); 160 if( pColl ){ 161 CollSeq *pDel = 0; 162 pColl[0].zName = (char*)&pColl[3]; 163 pColl[0].enc = SQLITE_UTF8; 164 pColl[1].zName = (char*)&pColl[3]; 165 pColl[1].enc = SQLITE_UTF16LE; 166 pColl[2].zName = (char*)&pColl[3]; 167 pColl[2].enc = SQLITE_UTF16BE; 168 memcpy(pColl[0].zName, zName, nName); 169 pColl[0].zName[nName] = 0; 170 pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl); 171 172 /* If a malloc() failure occurred in sqlite3HashInsert(), it will 173 ** return the pColl pointer to be deleted (because it wasn't added 174 ** to the hash table). 175 */ 176 assert( pDel==0 || pDel==pColl ); 177 if( pDel!=0 ){ 178 db->mallocFailed = 1; 179 sqlite3DbFree(db, pDel); 180 pColl = 0; 181 } 182 } 183 } 184 return pColl; 185} 186 187/* 188** Parameter zName points to a UTF-8 encoded string nName bytes long. 189** Return the CollSeq* pointer for the collation sequence named zName 190** for the encoding 'enc' from the database 'db'. 191** 192** If the entry specified is not found and 'create' is true, then create a 193** new entry. Otherwise return NULL. 194** 195** A separate function sqlite3LocateCollSeq() is a wrapper around 196** this routine. sqlite3LocateCollSeq() invokes the collation factory 197** if necessary and generates an error message if the collating sequence 198** cannot be found. 199** 200** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq() 201*/ 202CollSeq *sqlite3FindCollSeq( 203 sqlite3 *db, 204 u8 enc, 205 const char *zName, 206 int create 207){ 208 CollSeq *pColl; 209 if( zName ){ 210 pColl = findCollSeqEntry(db, zName, create); 211 }else{ 212 pColl = db->pDfltColl; 213 } 214 assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 ); 215 assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE ); 216 if( pColl ) pColl += enc-1; 217 return pColl; 218} 219 220/* During the search for the best function definition, this procedure 221** is called to test how well the function passed as the first argument 222** matches the request for a function with nArg arguments in a system 223** that uses encoding enc. The value returned indicates how well the 224** request is matched. A higher value indicates a better match. 225** 226** The returned value is always between 0 and 6, as follows: 227** 228** 0: Not a match, or if nArg<0 and the function is has no implementation. 229** 1: A variable arguments function that prefers UTF-8 when a UTF-16 230** encoding is requested, or vice versa. 231** 2: A variable arguments function that uses UTF-16BE when UTF-16LE is 232** requested, or vice versa. 233** 3: A variable arguments function using the same text encoding. 234** 4: A function with the exact number of arguments requested that 235** prefers UTF-8 when a UTF-16 encoding is requested, or vice versa. 236** 5: A function with the exact number of arguments requested that 237** prefers UTF-16LE when UTF-16BE is requested, or vice versa. 238** 6: An exact match. 239** 240*/ 241static int matchQuality(FuncDef *p, int nArg, u8 enc){ 242 int match = 0; 243 if( p->nArg==-1 || p->nArg==nArg 244 || (nArg==-1 && (p->xFunc!=0 || p->xStep!=0)) 245 ){ 246 match = 1; 247 if( p->nArg==nArg || nArg==-1 ){ 248 match = 4; 249 } 250 if( enc==p->iPrefEnc ){ 251 match += 2; 252 } 253 else if( (enc==SQLITE_UTF16LE && p->iPrefEnc==SQLITE_UTF16BE) || 254 (enc==SQLITE_UTF16BE && p->iPrefEnc==SQLITE_UTF16LE) ){ 255 match += 1; 256 } 257 } 258 return match; 259} 260 261/* 262** Search a FuncDefHash for a function with the given name. Return 263** a pointer to the matching FuncDef if found, or 0 if there is no match. 264*/ 265static FuncDef *functionSearch( 266 FuncDefHash *pHash, /* Hash table to search */ 267 int h, /* Hash of the name */ 268 const char *zFunc, /* Name of function */ 269 int nFunc /* Number of bytes in zFunc */ 270){ 271 FuncDef *p; 272 for(p=pHash->a[h]; p; p=p->pHash){ 273 if( sqlite3StrNICmp(p->zName, zFunc, nFunc)==0 && p->zName[nFunc]==0 ){ 274 return p; 275 } 276 } 277 return 0; 278} 279 280/* 281** Insert a new FuncDef into a FuncDefHash hash table. 282*/ 283void sqlite3FuncDefInsert( 284 FuncDefHash *pHash, /* The hash table into which to insert */ 285 FuncDef *pDef /* The function definition to insert */ 286){ 287 FuncDef *pOther; 288 int nName = sqlite3Strlen30(pDef->zName); 289 u8 c1 = (u8)pDef->zName[0]; 290 int h = (sqlite3UpperToLower[c1] + nName) % ArraySize(pHash->a); 291 pOther = functionSearch(pHash, h, pDef->zName, nName); 292 if( pOther ){ 293 assert( pOther!=pDef && pOther->pNext!=pDef ); 294 pDef->pNext = pOther->pNext; 295 pOther->pNext = pDef; 296 }else{ 297 pDef->pNext = 0; 298 pDef->pHash = pHash->a[h]; 299 pHash->a[h] = pDef; 300 } 301} 302 303 304 305/* 306** Locate a user function given a name, a number of arguments and a flag 307** indicating whether the function prefers UTF-16 over UTF-8. Return a 308** pointer to the FuncDef structure that defines that function, or return 309** NULL if the function does not exist. 310** 311** If the createFlag argument is true, then a new (blank) FuncDef 312** structure is created and liked into the "db" structure if a 313** no matching function previously existed. When createFlag is true 314** and the nArg parameter is -1, then only a function that accepts 315** any number of arguments will be returned. 316** 317** If createFlag is false and nArg is -1, then the first valid 318** function found is returned. A function is valid if either xFunc 319** or xStep is non-zero. 320** 321** If createFlag is false, then a function with the required name and 322** number of arguments may be returned even if the eTextRep flag does not 323** match that requested. 324*/ 325FuncDef *sqlite3FindFunction( 326 sqlite3 *db, /* An open database */ 327 const char *zName, /* Name of the function. Not null-terminated */ 328 int nName, /* Number of characters in the name */ 329 int nArg, /* Number of arguments. -1 means any number */ 330 u8 enc, /* Preferred text encoding */ 331 int createFlag /* Create new entry if true and does not otherwise exist */ 332){ 333 FuncDef *p; /* Iterator variable */ 334 FuncDef *pBest = 0; /* Best match found so far */ 335 int bestScore = 0; /* Score of best match */ 336 int h; /* Hash value */ 337 338 339 assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE ); 340 h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a); 341 342 /* First search for a match amongst the application-defined functions. 343 */ 344 p = functionSearch(&db->aFunc, h, zName, nName); 345 while( p ){ 346 int score = matchQuality(p, nArg, enc); 347 if( score>bestScore ){ 348 pBest = p; 349 bestScore = score; 350 } 351 p = p->pNext; 352 } 353 354 /* If no match is found, search the built-in functions. 355 ** 356 ** If the SQLITE_PreferBuiltin flag is set, then search the built-in 357 ** functions even if a prior app-defined function was found. And give 358 ** priority to built-in functions. 359 ** 360 ** Except, if createFlag is true, that means that we are trying to 361 ** install a new function. Whatever FuncDef structure is returned it will 362 ** have fields overwritten with new information appropriate for the 363 ** new function. But the FuncDefs for built-in functions are read-only. 364 ** So we must not search for built-ins when creating a new function. 365 */ 366 if( !createFlag && (pBest==0 || (db->flags & SQLITE_PreferBuiltin)!=0) ){ 367 FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions); 368 bestScore = 0; 369 p = functionSearch(pHash, h, zName, nName); 370 while( p ){ 371 int score = matchQuality(p, nArg, enc); 372 if( score>bestScore ){ 373 pBest = p; 374 bestScore = score; 375 } 376 p = p->pNext; 377 } 378 } 379 380 /* If the createFlag parameter is true and the search did not reveal an 381 ** exact match for the name, number of arguments and encoding, then add a 382 ** new entry to the hash table and return it. 383 */ 384 if( createFlag && (bestScore<6 || pBest->nArg!=nArg) && 385 (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){ 386 pBest->zName = (char *)&pBest[1]; 387 pBest->nArg = (u16)nArg; 388 pBest->iPrefEnc = enc; 389 memcpy(pBest->zName, zName, nName); 390 pBest->zName[nName] = 0; 391 sqlite3FuncDefInsert(&db->aFunc, pBest); 392 } 393 394 if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){ 395 return pBest; 396 } 397 return 0; 398} 399 400/* 401** Free all resources held by the schema structure. The void* argument points 402** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the 403** pointer itself, it just cleans up subsidiary resources (i.e. the contents 404** of the schema hash tables). 405** 406** The Schema.cache_size variable is not cleared. 407*/ 408void sqlite3SchemaClear(void *p){ 409 Hash temp1; 410 Hash temp2; 411 HashElem *pElem; 412 Schema *pSchema = (Schema *)p; 413 414 temp1 = pSchema->tblHash; 415 temp2 = pSchema->trigHash; 416 sqlite3HashInit(&pSchema->trigHash); 417 sqlite3HashClear(&pSchema->idxHash); 418 for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){ 419 sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem)); 420 } 421 sqlite3HashClear(&temp2); 422 sqlite3HashInit(&pSchema->tblHash); 423 for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){ 424 Table *pTab = sqliteHashData(pElem); 425 sqlite3DeleteTable(0, pTab); 426 } 427 sqlite3HashClear(&temp1); 428 sqlite3HashClear(&pSchema->fkeyHash); 429 pSchema->pSeqTab = 0; 430 if( pSchema->flags & DB_SchemaLoaded ){ 431 pSchema->iGeneration++; 432 pSchema->flags &= ~DB_SchemaLoaded; 433 } 434} 435 436/* 437** Find and return the schema associated with a BTree. Create 438** a new one if necessary. 439*/ 440Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){ 441 Schema * p; 442 if( pBt ){ 443 p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear); 444 }else{ 445 p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema)); 446 } 447 if( !p ){ 448 db->mallocFailed = 1; 449 }else if ( 0==p->file_format ){ 450 sqlite3HashInit(&p->tblHash); 451 sqlite3HashInit(&p->idxHash); 452 sqlite3HashInit(&p->trigHash); 453 sqlite3HashInit(&p->fkeyHash); 454 p->enc = SQLITE_UTF8; 455 } 456 return p; 457} 458