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 */
callCollNeeded(sqlite3 * db,int enc,const char * zName)23 static 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 */
synthCollSeq(sqlite3 * db,CollSeq * pColl)52 static 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. If no collation is found, leave an error message.
79 **
80 ** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq()
81 */
sqlite3GetCollSeq(Parse * pParse,u8 enc,CollSeq * pColl,const char * zName)82 CollSeq *sqlite3GetCollSeq(
83 Parse *pParse, /* Parsing context */
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 sqlite3 *db = pParse->db;
90
91 p = pColl;
92 if( !p ){
93 p = sqlite3FindCollSeq(db, enc, zName, 0);
94 }
95 if( !p || !p->xCmp ){
96 /* No collation sequence of this type for this encoding is registered.
97 ** Call the collation factory to see if it can supply us with one.
98 */
99 callCollNeeded(db, enc, zName);
100 p = sqlite3FindCollSeq(db, enc, zName, 0);
101 }
102 if( p && !p->xCmp && synthCollSeq(db, p) ){
103 p = 0;
104 }
105 assert( !p || p->xCmp );
106 if( p==0 ){
107 sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);
108 }
109 return p;
110 }
111
112 /*
113 ** This routine is called on a collation sequence before it is used to
114 ** check that it is defined. An undefined collation sequence exists when
115 ** a database is loaded that contains references to collation sequences
116 ** that have not been defined by sqlite3_create_collation() etc.
117 **
118 ** If required, this routine calls the 'collation needed' callback to
119 ** request a definition of the collating sequence. If this doesn't work,
120 ** an equivalent collating sequence that uses a text encoding different
121 ** from the main database is substituted, if one is available.
122 */
sqlite3CheckCollSeq(Parse * pParse,CollSeq * pColl)123 int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){
124 if( pColl && pColl->xCmp==0 ){
125 const char *zName = pColl->zName;
126 sqlite3 *db = pParse->db;
127 CollSeq *p = sqlite3GetCollSeq(pParse, ENC(db), pColl, zName);
128 if( !p ){
129 return SQLITE_ERROR;
130 }
131 assert( p==pColl );
132 }
133 return SQLITE_OK;
134 }
135
136
137
138 /*
139 ** Locate and return an entry from the db.aCollSeq hash table. If the entry
140 ** specified by zName and nName is not found and parameter 'create' is
141 ** true, then create a new entry. Otherwise return NULL.
142 **
143 ** Each pointer stored in the sqlite3.aCollSeq hash table contains an
144 ** array of three CollSeq structures. The first is the collation sequence
145 ** preferred for UTF-8, the second UTF-16le, and the third UTF-16be.
146 **
147 ** Stored immediately after the three collation sequences is a copy of
148 ** the collation sequence name. A pointer to this string is stored in
149 ** each collation sequence structure.
150 */
findCollSeqEntry(sqlite3 * db,const char * zName,int create)151 static CollSeq *findCollSeqEntry(
152 sqlite3 *db, /* Database connection */
153 const char *zName, /* Name of the collating sequence */
154 int create /* Create a new entry if true */
155 ){
156 CollSeq *pColl;
157 pColl = sqlite3HashFind(&db->aCollSeq, zName);
158
159 if( 0==pColl && create ){
160 int nName = sqlite3Strlen30(zName) + 1;
161 pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName);
162 if( pColl ){
163 CollSeq *pDel = 0;
164 pColl[0].zName = (char*)&pColl[3];
165 pColl[0].enc = SQLITE_UTF8;
166 pColl[1].zName = (char*)&pColl[3];
167 pColl[1].enc = SQLITE_UTF16LE;
168 pColl[2].zName = (char*)&pColl[3];
169 pColl[2].enc = SQLITE_UTF16BE;
170 memcpy(pColl[0].zName, zName, nName);
171 pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl);
172
173 /* If a malloc() failure occurred in sqlite3HashInsert(), it will
174 ** return the pColl pointer to be deleted (because it wasn't added
175 ** to the hash table).
176 */
177 assert( pDel==0 || pDel==pColl );
178 if( pDel!=0 ){
179 sqlite3OomFault(db);
180 sqlite3DbFree(db, pDel);
181 pColl = 0;
182 }
183 }
184 }
185 return pColl;
186 }
187
188 /*
189 ** Parameter zName points to a UTF-8 encoded string nName bytes long.
190 ** Return the CollSeq* pointer for the collation sequence named zName
191 ** for the encoding 'enc' from the database 'db'.
192 **
193 ** If the entry specified is not found and 'create' is true, then create a
194 ** new entry. Otherwise return NULL.
195 **
196 ** A separate function sqlite3LocateCollSeq() is a wrapper around
197 ** this routine. sqlite3LocateCollSeq() invokes the collation factory
198 ** if necessary and generates an error message if the collating sequence
199 ** cannot be found.
200 **
201 ** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq()
202 */
sqlite3FindCollSeq(sqlite3 * db,u8 enc,const char * zName,int create)203 CollSeq *sqlite3FindCollSeq(
204 sqlite3 *db,
205 u8 enc,
206 const char *zName,
207 int create
208 ){
209 CollSeq *pColl;
210 if( zName ){
211 pColl = findCollSeqEntry(db, zName, create);
212 }else{
213 pColl = db->pDfltColl;
214 }
215 assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
216 assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );
217 if( pColl ) pColl += enc-1;
218 return pColl;
219 }
220
221 /* During the search for the best function definition, this procedure
222 ** is called to test how well the function passed as the first argument
223 ** matches the request for a function with nArg arguments in a system
224 ** that uses encoding enc. The value returned indicates how well the
225 ** request is matched. A higher value indicates a better match.
226 **
227 ** If nArg is -1 that means to only return a match (non-zero) if p->nArg
228 ** is also -1. In other words, we are searching for a function that
229 ** takes a variable number of arguments.
230 **
231 ** If nArg is -2 that means that we are searching for any function
232 ** regardless of the number of arguments it uses, so return a positive
233 ** match score for any
234 **
235 ** The returned value is always between 0 and 6, as follows:
236 **
237 ** 0: Not a match.
238 ** 1: UTF8/16 conversion required and function takes any number of arguments.
239 ** 2: UTF16 byte order change required and function takes any number of args.
240 ** 3: encoding matches and function takes any number of arguments
241 ** 4: UTF8/16 conversion required - argument count matches exactly
242 ** 5: UTF16 byte order conversion required - argument count matches exactly
243 ** 6: Perfect match: encoding and argument count match exactly.
244 **
245 ** If nArg==(-2) then any function with a non-null xSFunc is
246 ** a perfect match and any function with xSFunc NULL is
247 ** a non-match.
248 */
249 #define FUNC_PERFECT_MATCH 6 /* The score for a perfect match */
matchQuality(FuncDef * p,int nArg,u8 enc)250 static int matchQuality(
251 FuncDef *p, /* The function we are evaluating for match quality */
252 int nArg, /* Desired number of arguments. (-1)==any */
253 u8 enc /* Desired text encoding */
254 ){
255 int match;
256
257 /* nArg of -2 is a special case */
258 if( nArg==(-2) ) return (p->xSFunc==0) ? 0 : FUNC_PERFECT_MATCH;
259
260 /* Wrong number of arguments means "no match" */
261 if( p->nArg!=nArg && p->nArg>=0 ) return 0;
262
263 /* Give a better score to a function with a specific number of arguments
264 ** than to function that accepts any number of arguments. */
265 if( p->nArg==nArg ){
266 match = 4;
267 }else{
268 match = 1;
269 }
270
271 /* Bonus points if the text encoding matches */
272 if( enc==(p->funcFlags & SQLITE_FUNC_ENCMASK) ){
273 match += 2; /* Exact encoding match */
274 }else if( (enc & p->funcFlags & 2)!=0 ){
275 match += 1; /* Both are UTF16, but with different byte orders */
276 }
277
278 return match;
279 }
280
281 /*
282 ** Search a FuncDefHash for a function with the given name. Return
283 ** a pointer to the matching FuncDef if found, or 0 if there is no match.
284 */
functionSearch(int h,const char * zFunc)285 static FuncDef *functionSearch(
286 int h, /* Hash of the name */
287 const char *zFunc /* Name of function */
288 ){
289 FuncDef *p;
290 for(p=sqlite3BuiltinFunctions.a[h]; p; p=p->u.pHash){
291 if( sqlite3StrICmp(p->zName, zFunc)==0 ){
292 return p;
293 }
294 }
295 return 0;
296 }
297
298 /*
299 ** Insert a new FuncDef into a FuncDefHash hash table.
300 */
sqlite3InsertBuiltinFuncs(FuncDef * aDef,int nDef)301 void sqlite3InsertBuiltinFuncs(
302 FuncDef *aDef, /* List of global functions to be inserted */
303 int nDef /* Length of the apDef[] list */
304 ){
305 int i;
306 for(i=0; i<nDef; i++){
307 FuncDef *pOther;
308 const char *zName = aDef[i].zName;
309 int nName = sqlite3Strlen30(zName);
310 int h = (zName[0] + nName) % SQLITE_FUNC_HASH_SZ;
311 assert( zName[0]>='a' && zName[0]<='z' );
312 pOther = functionSearch(h, zName);
313 if( pOther ){
314 assert( pOther!=&aDef[i] && pOther->pNext!=&aDef[i] );
315 aDef[i].pNext = pOther->pNext;
316 pOther->pNext = &aDef[i];
317 }else{
318 aDef[i].pNext = 0;
319 aDef[i].u.pHash = sqlite3BuiltinFunctions.a[h];
320 sqlite3BuiltinFunctions.a[h] = &aDef[i];
321 }
322 }
323 }
324
325
326
327 /*
328 ** Locate a user function given a name, a number of arguments and a flag
329 ** indicating whether the function prefers UTF-16 over UTF-8. Return a
330 ** pointer to the FuncDef structure that defines that function, or return
331 ** NULL if the function does not exist.
332 **
333 ** If the createFlag argument is true, then a new (blank) FuncDef
334 ** structure is created and liked into the "db" structure if a
335 ** no matching function previously existed.
336 **
337 ** If nArg is -2, then the first valid function found is returned. A
338 ** function is valid if xSFunc is non-zero. The nArg==(-2)
339 ** case is used to see if zName is a valid function name for some number
340 ** of arguments. If nArg is -2, then createFlag must be 0.
341 **
342 ** If createFlag is false, then a function with the required name and
343 ** number of arguments may be returned even if the eTextRep flag does not
344 ** match that requested.
345 */
sqlite3FindFunction(sqlite3 * db,const char * zName,int nArg,u8 enc,u8 createFlag)346 FuncDef *sqlite3FindFunction(
347 sqlite3 *db, /* An open database */
348 const char *zName, /* Name of the function. zero-terminated */
349 int nArg, /* Number of arguments. -1 means any number */
350 u8 enc, /* Preferred text encoding */
351 u8 createFlag /* Create new entry if true and does not otherwise exist */
352 ){
353 FuncDef *p; /* Iterator variable */
354 FuncDef *pBest = 0; /* Best match found so far */
355 int bestScore = 0; /* Score of best match */
356 int h; /* Hash value */
357 int nName; /* Length of the name */
358
359 assert( nArg>=(-2) );
360 assert( nArg>=(-1) || createFlag==0 );
361 nName = sqlite3Strlen30(zName);
362
363 /* First search for a match amongst the application-defined functions.
364 */
365 p = (FuncDef*)sqlite3HashFind(&db->aFunc, zName);
366 while( p ){
367 int score = matchQuality(p, nArg, enc);
368 if( score>bestScore ){
369 pBest = p;
370 bestScore = score;
371 }
372 p = p->pNext;
373 }
374
375 /* If no match is found, search the built-in functions.
376 **
377 ** If the SQLITE_PreferBuiltin flag is set, then search the built-in
378 ** functions even if a prior app-defined function was found. And give
379 ** priority to built-in functions.
380 **
381 ** Except, if createFlag is true, that means that we are trying to
382 ** install a new function. Whatever FuncDef structure is returned it will
383 ** have fields overwritten with new information appropriate for the
384 ** new function. But the FuncDefs for built-in functions are read-only.
385 ** So we must not search for built-ins when creating a new function.
386 */
387 if( !createFlag && (pBest==0 || (db->flags & SQLITE_PreferBuiltin)!=0) ){
388 bestScore = 0;
389 h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % SQLITE_FUNC_HASH_SZ;
390 p = functionSearch(h, zName);
391 while( p ){
392 int score = matchQuality(p, nArg, enc);
393 if( score>bestScore ){
394 pBest = p;
395 bestScore = score;
396 }
397 p = p->pNext;
398 }
399 }
400
401 /* If the createFlag parameter is true and the search did not reveal an
402 ** exact match for the name, number of arguments and encoding, then add a
403 ** new entry to the hash table and return it.
404 */
405 if( createFlag && bestScore<FUNC_PERFECT_MATCH &&
406 (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){
407 FuncDef *pOther;
408 pBest->zName = (const char*)&pBest[1];
409 pBest->nArg = (u16)nArg;
410 pBest->funcFlags = enc;
411 memcpy((char*)&pBest[1], zName, nName+1);
412 pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest);
413 if( pOther==pBest ){
414 sqlite3DbFree(db, pBest);
415 sqlite3OomFault(db);
416 return 0;
417 }else{
418 pBest->pNext = pOther;
419 }
420 }
421
422 if( pBest && (pBest->xSFunc || createFlag) ){
423 return pBest;
424 }
425 return 0;
426 }
427
428 /*
429 ** Free all resources held by the schema structure. The void* argument points
430 ** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the
431 ** pointer itself, it just cleans up subsidiary resources (i.e. the contents
432 ** of the schema hash tables).
433 **
434 ** The Schema.cache_size variable is not cleared.
435 */
sqlite3SchemaClear(void * p)436 void sqlite3SchemaClear(void *p){
437 Hash temp1;
438 Hash temp2;
439 HashElem *pElem;
440 Schema *pSchema = (Schema *)p;
441
442 temp1 = pSchema->tblHash;
443 temp2 = pSchema->trigHash;
444 sqlite3HashInit(&pSchema->trigHash);
445 sqlite3HashClear(&pSchema->idxHash);
446 for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
447 sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));
448 }
449 sqlite3HashClear(&temp2);
450 sqlite3HashInit(&pSchema->tblHash);
451 for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
452 Table *pTab = sqliteHashData(pElem);
453 sqlite3DeleteTable(0, pTab);
454 }
455 sqlite3HashClear(&temp1);
456 sqlite3HashClear(&pSchema->fkeyHash);
457 pSchema->pSeqTab = 0;
458 if( pSchema->schemaFlags & DB_SchemaLoaded ){
459 pSchema->iGeneration++;
460 pSchema->schemaFlags &= ~DB_SchemaLoaded;
461 }
462 }
463
464 /*
465 ** Find and return the schema associated with a BTree. Create
466 ** a new one if necessary.
467 */
sqlite3SchemaGet(sqlite3 * db,Btree * pBt)468 Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){
469 Schema * p;
470 if( pBt ){
471 p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);
472 }else{
473 p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));
474 }
475 if( !p ){
476 sqlite3OomFault(db);
477 }else if ( 0==p->file_format ){
478 sqlite3HashInit(&p->tblHash);
479 sqlite3HashInit(&p->idxHash);
480 sqlite3HashInit(&p->trigHash);
481 sqlite3HashInit(&p->fkeyHash);
482 p->enc = SQLITE_UTF8;
483 }
484 return p;
485 }
486