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 : ** $Id: callback.c 234062 2007-04-18 22:53:46Z iliaa $
17 : */
18 :
19 : #include "sqliteInt.h"
20 :
21 : /*
22 : ** Invoke the 'collation needed' callback to request a collation sequence
23 : ** in the database text encoding of name zName, length nName.
24 : ** If the collation sequence
25 : */
26 0 : static void callCollNeeded(sqlite3 *db, const char *zName, int nName){
27 : assert( !db->xCollNeeded || !db->xCollNeeded16 );
28 0 : if( nName<0 ) nName = strlen(zName);
29 0 : if( db->xCollNeeded ){
30 0 : char *zExternal = sqliteStrNDup(zName, nName);
31 0 : if( !zExternal ) return;
32 0 : db->xCollNeeded(db->pCollNeededArg, db, (int)ENC(db), zExternal);
33 0 : sqliteFree(zExternal);
34 : }
35 : #ifndef SQLITE_OMIT_UTF16
36 0 : if( db->xCollNeeded16 ){
37 : char const *zExternal;
38 0 : sqlite3_value *pTmp = sqlite3ValueNew();
39 0 : sqlite3ValueSetStr(pTmp, nName, zName, SQLITE_UTF8, SQLITE_STATIC);
40 0 : zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);
41 0 : if( zExternal ){
42 0 : db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);
43 : }
44 0 : sqlite3ValueFree(pTmp);
45 : }
46 : #endif
47 : }
48 :
49 : /*
50 : ** This routine is called if the collation factory fails to deliver a
51 : ** collation function in the best encoding but there may be other versions
52 : ** of this collation function (for other text encodings) available. Use one
53 : ** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if
54 : ** possible.
55 : */
56 0 : static int synthCollSeq(sqlite3 *db, CollSeq *pColl){
57 : CollSeq *pColl2;
58 0 : char *z = pColl->zName;
59 0 : int n = strlen(z);
60 : int i;
61 : static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };
62 0 : for(i=0; i<3; i++){
63 0 : pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, n, 0);
64 0 : if( pColl2->xCmp!=0 ){
65 0 : memcpy(pColl, pColl2, sizeof(CollSeq));
66 0 : return SQLITE_OK;
67 : }
68 : }
69 0 : return SQLITE_ERROR;
70 : }
71 :
72 : /*
73 : ** This function is responsible for invoking the collation factory callback
74 : ** or substituting a collation sequence of a different encoding when the
75 : ** requested collation sequence is not available in the database native
76 : ** encoding.
77 : **
78 : ** If it is not NULL, then pColl must point to the database native encoding
79 : ** collation sequence with name zName, length nName.
80 : **
81 : ** The return value is either the collation sequence to be used in database
82 : ** db for collation type name zName, length nName, or NULL, if no collation
83 : ** sequence can be found.
84 : */
85 : CollSeq *sqlite3GetCollSeq(
86 : sqlite3* db,
87 : CollSeq *pColl,
88 : const char *zName,
89 : int nName
90 106 : ){
91 : CollSeq *p;
92 :
93 106 : p = pColl;
94 106 : if( !p ){
95 0 : p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);
96 : }
97 106 : if( !p || !p->xCmp ){
98 : /* No collation sequence of this type for this encoding is registered.
99 : ** Call the collation factory to see if it can supply us with one.
100 : */
101 0 : callCollNeeded(db, zName, nName);
102 0 : p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);
103 : }
104 106 : if( p && !p->xCmp && synthCollSeq(db, p) ){
105 0 : p = 0;
106 : }
107 : assert( !p || p->xCmp );
108 106 : return p;
109 : }
110 :
111 : /*
112 : ** This routine is called on a collation sequence before it is used to
113 : ** check that it is defined. An undefined collation sequence exists when
114 : ** a database is loaded that contains references to collation sequences
115 : ** that have not been defined by sqlite3_create_collation() etc.
116 : **
117 : ** If required, this routine calls the 'collation needed' callback to
118 : ** request a definition of the collating sequence. If this doesn't work,
119 : ** an equivalent collating sequence that uses a text encoding different
120 : ** from the main database is substituted, if one is available.
121 : */
122 106 : int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){
123 106 : if( pColl ){
124 106 : const char *zName = pColl->zName;
125 106 : CollSeq *p = sqlite3GetCollSeq(pParse->db, pColl, zName, -1);
126 106 : if( !p ){
127 0 : if( pParse->nErr==0 ){
128 0 : sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);
129 : }
130 0 : pParse->nErr++;
131 0 : return SQLITE_ERROR;
132 : }
133 : assert( p==pColl );
134 : }
135 106 : return SQLITE_OK;
136 : }
137 :
138 :
139 :
140 : /*
141 : ** Locate and return an entry from the db.aCollSeq hash table. If the entry
142 : ** specified by zName and nName is not found and parameter 'create' is
143 : ** true, then create a new entry. Otherwise return NULL.
144 : **
145 : ** Each pointer stored in the sqlite3.aCollSeq hash table contains an
146 : ** array of three CollSeq structures. The first is the collation sequence
147 : ** prefferred for UTF-8, the second UTF-16le, and the third UTF-16be.
148 : **
149 : ** Stored immediately after the three collation sequences is a copy of
150 : ** the collation sequence name. A pointer to this string is stored in
151 : ** each collation sequence structure.
152 : */
153 : static CollSeq *findCollSeqEntry(
154 : sqlite3 *db,
155 : const char *zName,
156 : int nName,
157 : int create
158 1451 : ){
159 : CollSeq *pColl;
160 1451 : if( nName<0 ) nName = strlen(zName);
161 1451 : pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);
162 :
163 1451 : if( 0==pColl && create ){
164 260 : pColl = sqliteMalloc( 3*sizeof(*pColl) + nName + 1 );
165 260 : if( pColl ){
166 260 : CollSeq *pDel = 0;
167 260 : pColl[0].zName = (char*)&pColl[3];
168 260 : pColl[0].enc = SQLITE_UTF8;
169 260 : pColl[1].zName = (char*)&pColl[3];
170 260 : pColl[1].enc = SQLITE_UTF16LE;
171 260 : pColl[2].zName = (char*)&pColl[3];
172 260 : pColl[2].enc = SQLITE_UTF16BE;
173 260 : memcpy(pColl[0].zName, zName, nName);
174 260 : pColl[0].zName[nName] = 0;
175 260 : pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl);
176 :
177 : /* If a malloc() failure occured in sqlite3HashInsert(), it will
178 : ** return the pColl pointer to be deleted (because it wasn't added
179 : ** to the hash table).
180 : */
181 : assert( !pDel || (sqlite3MallocFailed() && pDel==pColl) );
182 260 : if( pDel ){
183 0 : sqliteFree(pDel);
184 0 : pColl = 0;
185 : }
186 : }
187 : }
188 1451 : return pColl;
189 : }
190 :
191 : /*
192 : ** Parameter zName points to a UTF-8 encoded string nName bytes long.
193 : ** Return the CollSeq* pointer for the collation sequence named zName
194 : ** for the encoding 'enc' from the database 'db'.
195 : **
196 : ** If the entry specified is not found and 'create' is true, then create a
197 : ** new entry. Otherwise return NULL.
198 : **
199 : ** A separate function sqlite3LocateCollSeq() is a wrapper around
200 : ** this routine. sqlite3LocateCollSeq() invokes the collation factory
201 : ** if necessary and generates an error message if the collating sequence
202 : ** cannot be found.
203 : */
204 : CollSeq *sqlite3FindCollSeq(
205 : sqlite3 *db,
206 : u8 enc,
207 : const char *zName,
208 : int nName,
209 : int create
210 1877 : ){
211 : CollSeq *pColl;
212 1877 : if( zName ){
213 1451 : pColl = findCollSeqEntry(db, zName, nName, create);
214 : }else{
215 426 : pColl = db->pDfltColl;
216 : }
217 : assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
218 : assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );
219 1877 : if( pColl ) pColl += enc-1;
220 1877 : return pColl;
221 : }
222 :
223 : /*
224 : ** Locate a user function given a name, a number of arguments and a flag
225 : ** indicating whether the function prefers UTF-16 over UTF-8. Return a
226 : ** pointer to the FuncDef structure that defines that function, or return
227 : ** NULL if the function does not exist.
228 : **
229 : ** If the createFlag argument is true, then a new (blank) FuncDef
230 : ** structure is created and liked into the "db" structure if a
231 : ** no matching function previously existed. When createFlag is true
232 : ** and the nArg parameter is -1, then only a function that accepts
233 : ** any number of arguments will be returned.
234 : **
235 : ** If createFlag is false and nArg is -1, then the first valid
236 : ** function found is returned. A function is valid if either xFunc
237 : ** or xStep is non-zero.
238 : **
239 : ** If createFlag is false, then a function with the required name and
240 : ** number of arguments may be returned even if the eTextRep flag does not
241 : ** match that requested.
242 : */
243 : FuncDef *sqlite3FindFunction(
244 : sqlite3 *db, /* An open database */
245 : const char *zName, /* Name of the function. Not null-terminated */
246 : int nName, /* Number of characters in the name */
247 : int nArg, /* Number of arguments. -1 means any number */
248 : u8 enc, /* Preferred text encoding */
249 : int createFlag /* Create new entry if true and does not otherwise exist */
250 16548 : ){
251 : FuncDef *p; /* Iterator variable */
252 : FuncDef *pFirst; /* First function with this name */
253 16548 : FuncDef *pBest = 0; /* Best match found so far */
254 16548 : int bestmatch = 0;
255 :
256 :
257 : assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
258 16548 : if( nArg<-1 ) nArg = -1;
259 :
260 16548 : pFirst = (FuncDef*)sqlite3HashFind(&db->aFunc, zName, nName);
261 23238 : for(p=pFirst; p; p=p->pNext){
262 : /* During the search for the best function definition, bestmatch is set
263 : ** as follows to indicate the quality of the match with the definition
264 : ** pointed to by pBest:
265 : **
266 : ** 0: pBest is NULL. No match has been found.
267 : ** 1: A variable arguments function that prefers UTF-8 when a UTF-16
268 : ** encoding is requested, or vice versa.
269 : ** 2: A variable arguments function that uses UTF-16BE when UTF-16LE is
270 : ** requested, or vice versa.
271 : ** 3: A variable arguments function using the same text encoding.
272 : ** 4: A function with the exact number of arguments requested that
273 : ** prefers UTF-8 when a UTF-16 encoding is requested, or vice versa.
274 : ** 5: A function with the exact number of arguments requested that
275 : ** prefers UTF-16LE when UTF-16BE is requested, or vice versa.
276 : ** 6: An exact match.
277 : **
278 : ** A larger value of 'matchqual' indicates a more desirable match.
279 : */
280 6690 : if( p->nArg==-1 || p->nArg==nArg || nArg==-1 ){
281 3674 : int match = 1; /* Quality of this match */
282 3674 : if( p->nArg==nArg || nArg==-1 ){
283 1590 : match = 4;
284 : }
285 3674 : if( enc==p->iPrefEnc ){
286 3414 : match += 2;
287 : }
288 260 : else if( (enc==SQLITE_UTF16LE && p->iPrefEnc==SQLITE_UTF16BE) ||
289 : (enc==SQLITE_UTF16BE && p->iPrefEnc==SQLITE_UTF16LE) ){
290 0 : match += 1;
291 : }
292 :
293 3674 : if( match>bestmatch ){
294 3154 : pBest = p;
295 3154 : bestmatch = match;
296 : }
297 : }
298 : }
299 :
300 : /* If the createFlag parameter is true, and the seach did not reveal an
301 : ** exact match for the name, number of arguments and encoding, then add a
302 : ** new entry to the hash table and return it.
303 : */
304 16548 : if( createFlag && bestmatch<6 &&
305 : (pBest = sqliteMalloc(sizeof(*pBest)+nName))!=0 ){
306 7542 : pBest->nArg = nArg;
307 7542 : pBest->pNext = pFirst;
308 7542 : pBest->iPrefEnc = enc;
309 7542 : memcpy(pBest->zName, zName, nName);
310 7542 : pBest->zName[nName] = 0;
311 7542 : if( pBest==sqlite3HashInsert(&db->aFunc,pBest->zName,nName,(void*)pBest) ){
312 0 : sqliteFree(pBest);
313 0 : return 0;
314 : }
315 : }
316 :
317 16548 : if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){
318 9526 : return pBest;
319 : }
320 7022 : return 0;
321 : }
322 :
323 : /*
324 : ** Free all resources held by the schema structure. The void* argument points
325 : ** at a Schema struct. This function does not call sqliteFree() on the
326 : ** pointer itself, it just cleans up subsiduary resources (i.e. the contents
327 : ** of the schema hash tables).
328 : */
329 516 : void sqlite3SchemaFree(void *p){
330 : Hash temp1;
331 : Hash temp2;
332 : HashElem *pElem;
333 516 : Schema *pSchema = (Schema *)p;
334 :
335 516 : temp1 = pSchema->tblHash;
336 516 : temp2 = pSchema->trigHash;
337 516 : sqlite3HashInit(&pSchema->trigHash, SQLITE_HASH_STRING, 0);
338 516 : sqlite3HashClear(&pSchema->aFKey);
339 516 : sqlite3HashClear(&pSchema->idxHash);
340 516 : for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
341 0 : sqlite3DeleteTrigger((Trigger*)sqliteHashData(pElem));
342 : }
343 516 : sqlite3HashClear(&temp2);
344 516 : sqlite3HashInit(&pSchema->tblHash, SQLITE_HASH_STRING, 0);
345 782 : for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
346 266 : Table *pTab = sqliteHashData(pElem);
347 266 : sqlite3DeleteTable(pTab);
348 : }
349 516 : sqlite3HashClear(&temp1);
350 516 : pSchema->pSeqTab = 0;
351 516 : pSchema->flags &= ~DB_SchemaLoaded;
352 516 : }
353 :
354 : /*
355 : ** Find and return the schema associated with a BTree. Create
356 : ** a new one if necessary.
357 : */
358 260 : Schema *sqlite3SchemaGet(Btree *pBt){
359 : Schema * p;
360 260 : if( pBt ){
361 130 : p = (Schema *)sqlite3BtreeSchema(pBt,sizeof(Schema),sqlite3SchemaFree);
362 : }else{
363 130 : p = (Schema *)sqliteMalloc(sizeof(Schema));
364 : }
365 260 : if( p && 0==p->file_format ){
366 260 : sqlite3HashInit(&p->tblHash, SQLITE_HASH_STRING, 0);
367 260 : sqlite3HashInit(&p->idxHash, SQLITE_HASH_STRING, 0);
368 260 : sqlite3HashInit(&p->trigHash, SQLITE_HASH_STRING, 0);
369 260 : sqlite3HashInit(&p->aFKey, SQLITE_HASH_STRING, 1);
370 260 : p->enc = SQLITE_UTF8;
371 : }
372 260 : return p;
373 : }
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