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Diffstat (limited to 'src/callback.c')
| -rw-r--r-- | src/callback.c | 540 |
1 files changed, 540 insertions, 0 deletions
diff --git a/src/callback.c b/src/callback.c new file mode 100644 index 0000000..c36d51a --- /dev/null +++ b/src/callback.c @@ -0,0 +1,540 @@ +/* +** 2005 May 23 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** +** This file contains functions used to access the internal hash tables +** of user defined functions and collation sequences. +*/ + +#include "sqliteInt.h" + +/* +** Invoke the 'collation needed' callback to request a collation sequence +** in the encoding enc of name zName, length nName. +*/ +static void callCollNeeded(sqlite3 *db, int enc, const char *zName){ + assert( !db->xCollNeeded || !db->xCollNeeded16 ); + if( db->xCollNeeded ){ + char *zExternal = sqlite3DbStrDup(db, zName); + if( !zExternal ) return; + db->xCollNeeded(db->pCollNeededArg, db, enc, zExternal); + sqlite3DbFree(db, zExternal); + } +#ifndef SQLITE_OMIT_UTF16 + if( db->xCollNeeded16 ){ + char const *zExternal; + sqlite3_value *pTmp = sqlite3ValueNew(db); + sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF8, SQLITE_STATIC); + zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE); + if( zExternal ){ + db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal); + } + sqlite3ValueFree(pTmp); + } +#endif +} + +/* +** This routine is called if the collation factory fails to deliver a +** collation function in the best encoding but there may be other versions +** of this collation function (for other text encodings) available. Use one +** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if +** possible. +*/ +static int synthCollSeq(sqlite3 *db, CollSeq *pColl){ + CollSeq *pColl2; + char *z = pColl->zName; + int i; + static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 }; + for(i=0; i<3; i++){ + pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, 0); + if( pColl2->xCmp!=0 ){ + memcpy(pColl, pColl2, sizeof(CollSeq)); + pColl->xDel = 0; /* Do not copy the destructor */ + return SQLITE_OK; + } + } + return SQLITE_ERROR; +} + +/* +** This routine is called on a collation sequence before it is used to +** check that it is defined. An undefined collation sequence exists when +** a database is loaded that contains references to collation sequences +** that have not been defined by sqlite3_create_collation() etc. +** +** If required, this routine calls the 'collation needed' callback to +** request a definition of the collating sequence. If this doesn't work, +** an equivalent collating sequence that uses a text encoding different +** from the main database is substituted, if one is available. +*/ +int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){ + if( pColl && pColl->xCmp==0 ){ + const char *zName = pColl->zName; + sqlite3 *db = pParse->db; + CollSeq *p = sqlite3GetCollSeq(pParse, ENC(db), pColl, zName); + if( !p ){ + return SQLITE_ERROR; + } + assert( p==pColl ); + } + return SQLITE_OK; +} + + + +/* +** Locate and return an entry from the db.aCollSeq hash table. If the entry +** specified by zName and nName is not found and parameter 'create' is +** true, then create a new entry. Otherwise return NULL. +** +** Each pointer stored in the sqlite3.aCollSeq hash table contains an +** array of three CollSeq structures. The first is the collation sequence +** preferred for UTF-8, the second UTF-16le, and the third UTF-16be. +** +** Stored immediately after the three collation sequences is a copy of +** the collation sequence name. A pointer to this string is stored in +** each collation sequence structure. +*/ +static CollSeq *findCollSeqEntry( + sqlite3 *db, /* Database connection */ + const char *zName, /* Name of the collating sequence */ + int create /* Create a new entry if true */ +){ + CollSeq *pColl; + pColl = sqlite3HashFind(&db->aCollSeq, zName); + + if( 0==pColl && create ){ + int nName = sqlite3Strlen30(zName) + 1; + pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName); + if( pColl ){ + CollSeq *pDel = 0; + pColl[0].zName = (char*)&pColl[3]; + pColl[0].enc = SQLITE_UTF8; + pColl[1].zName = (char*)&pColl[3]; + pColl[1].enc = SQLITE_UTF16LE; + pColl[2].zName = (char*)&pColl[3]; + pColl[2].enc = SQLITE_UTF16BE; + memcpy(pColl[0].zName, zName, nName); + pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, pColl); + + /* If a malloc() failure occurred in sqlite3HashInsert(), it will + ** return the pColl pointer to be deleted (because it wasn't added + ** to the hash table). + */ + assert( pDel==0 || pDel==pColl ); + if( pDel!=0 ){ + sqlite3OomFault(db); + sqlite3DbFree(db, pDel); + pColl = 0; + } + } + } + return pColl; +} + +/* +** Parameter zName points to a UTF-8 encoded string nName bytes long. +** Return the CollSeq* pointer for the collation sequence named zName +** for the encoding 'enc' from the database 'db'. +** +** If the entry specified is not found and 'create' is true, then create a +** new entry. Otherwise return NULL. +** +** A separate function sqlite3LocateCollSeq() is a wrapper around +** this routine. sqlite3LocateCollSeq() invokes the collation factory +** if necessary and generates an error message if the collating sequence +** cannot be found. +** +** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq() +*/ +CollSeq *sqlite3FindCollSeq( + sqlite3 *db, /* Database connection to search */ + u8 enc, /* Desired text encoding */ + const char *zName, /* Name of the collating sequence. Might be NULL */ + int create /* True to create CollSeq if doesn't already exist */ +){ + CollSeq *pColl; + assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 ); + assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE ); + if( zName ){ + pColl = findCollSeqEntry(db, zName, create); + if( pColl ) pColl += enc-1; + }else{ + pColl = db->pDfltColl; + } + return pColl; +} + +/* +** Change the text encoding for a database connection. This means that +** the pDfltColl must change as well. +*/ +void sqlite3SetTextEncoding(sqlite3 *db, u8 enc){ + assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE ); + db->enc = enc; + /* EVIDENCE-OF: R-08308-17224 The default collating function for all + ** strings is BINARY. + */ + db->pDfltColl = sqlite3FindCollSeq(db, enc, sqlite3StrBINARY, 0); + sqlite3ExpirePreparedStatements(db, 1); +} + +/* +** This function is responsible for invoking the collation factory callback +** or substituting a collation sequence of a different encoding when the +** requested collation sequence is not available in the desired encoding. +** +** If it is not NULL, then pColl must point to the database native encoding +** collation sequence with name zName, length nName. +** +** The return value is either the collation sequence to be used in database +** db for collation type name zName, length nName, or NULL, if no collation +** sequence can be found. If no collation is found, leave an error message. +** +** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq() +*/ +CollSeq *sqlite3GetCollSeq( + Parse *pParse, /* Parsing context */ + u8 enc, /* The desired encoding for the collating sequence */ + CollSeq *pColl, /* Collating sequence with native encoding, or NULL */ + const char *zName /* Collating sequence name */ +){ + CollSeq *p; + sqlite3 *db = pParse->db; + + p = pColl; + if( !p ){ + p = sqlite3FindCollSeq(db, enc, zName, 0); + } + if( !p || !p->xCmp ){ + /* No collation sequence of this type for this encoding is registered. + ** Call the collation factory to see if it can supply us with one. + */ + callCollNeeded(db, enc, zName); + p = sqlite3FindCollSeq(db, enc, zName, 0); + } + if( p && !p->xCmp && synthCollSeq(db, p) ){ + p = 0; + } + assert( !p || p->xCmp ); + if( p==0 ){ + sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName); + pParse->rc = SQLITE_ERROR_MISSING_COLLSEQ; + } + return p; +} + +/* +** This function returns the collation sequence for database native text +** encoding identified by the string zName. +** +** If the requested collation sequence is not available, or not available +** in the database native encoding, the collation factory is invoked to +** request it. If the collation factory does not supply such a sequence, +** and the sequence is available in another text encoding, then that is +** returned instead. +** +** If no versions of the requested collations sequence are available, or +** another error occurs, NULL is returned and an error message written into +** pParse. +** +** This routine is a wrapper around sqlite3FindCollSeq(). This routine +** invokes the collation factory if the named collation cannot be found +** and generates an error message. +** +** See also: sqlite3FindCollSeq(), sqlite3GetCollSeq() +*/ +CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char *zName){ + sqlite3 *db = pParse->db; + u8 enc = ENC(db); + u8 initbusy = db->init.busy; + CollSeq *pColl; + + pColl = sqlite3FindCollSeq(db, enc, zName, initbusy); + if( !initbusy && (!pColl || !pColl->xCmp) ){ + pColl = sqlite3GetCollSeq(pParse, enc, pColl, zName); + } + + return pColl; +} + +/* During the search for the best function definition, this procedure +** is called to test how well the function passed as the first argument +** matches the request for a function with nArg arguments in a system +** that uses encoding enc. The value returned indicates how well the +** request is matched. A higher value indicates a better match. +** +** If nArg is -1 that means to only return a match (non-zero) if p->nArg +** is also -1. In other words, we are searching for a function that +** takes a variable number of arguments. +** +** If nArg is -2 that means that we are searching for any function +** regardless of the number of arguments it uses, so return a positive +** match score for any +** +** The returned value is always between 0 and 6, as follows: +** +** 0: Not a match. +** 1: UTF8/16 conversion required and function takes any number of arguments. +** 2: UTF16 byte order change required and function takes any number of args. +** 3: encoding matches and function takes any number of arguments +** 4: UTF8/16 conversion required - argument count matches exactly +** 5: UTF16 byte order conversion required - argument count matches exactly +** 6: Perfect match: encoding and argument count match exactly. +** +** If nArg==(-2) then any function with a non-null xSFunc is +** a perfect match and any function with xSFunc NULL is +** a non-match. +*/ +#define FUNC_PERFECT_MATCH 6 /* The score for a perfect match */ +static int matchQuality( + FuncDef *p, /* The function we are evaluating for match quality */ + int nArg, /* Desired number of arguments. (-1)==any */ + u8 enc /* Desired text encoding */ +){ + int match; + assert( p->nArg>=-1 ); + + /* Wrong number of arguments means "no match" */ + if( p->nArg!=nArg ){ + if( nArg==(-2) ) return (p->xSFunc==0) ? 0 : FUNC_PERFECT_MATCH; + if( p->nArg>=0 ) return 0; + } + + /* Give a better score to a function with a specific number of arguments + ** than to function that accepts any number of arguments. */ + if( p->nArg==nArg ){ + match = 4; + }else{ + match = 1; + } + + /* Bonus points if the text encoding matches */ + if( enc==(p->funcFlags & SQLITE_FUNC_ENCMASK) ){ + match += 2; /* Exact encoding match */ + }else if( (enc & p->funcFlags & 2)!=0 ){ + match += 1; /* Both are UTF16, but with different byte orders */ + } + + return match; +} + +/* +** Search a FuncDefHash for a function with the given name. Return +** a pointer to the matching FuncDef if found, or 0 if there is no match. +*/ +FuncDef *sqlite3FunctionSearch( + int h, /* Hash of the name */ + const char *zFunc /* Name of function */ +){ + FuncDef *p; + for(p=sqlite3BuiltinFunctions.a[h]; p; p=p->u.pHash){ + assert( p->funcFlags & SQLITE_FUNC_BUILTIN ); + if( sqlite3StrICmp(p->zName, zFunc)==0 ){ + return p; + } + } + return 0; +} + +/* +** Insert a new FuncDef into a FuncDefHash hash table. +*/ +void sqlite3InsertBuiltinFuncs( + FuncDef *aDef, /* List of global functions to be inserted */ + int nDef /* Length of the apDef[] list */ +){ + int i; + for(i=0; i<nDef; i++){ + FuncDef *pOther; + const char *zName = aDef[i].zName; + int nName = sqlite3Strlen30(zName); + int h = SQLITE_FUNC_HASH(zName[0], nName); + assert( aDef[i].funcFlags & SQLITE_FUNC_BUILTIN ); + pOther = sqlite3FunctionSearch(h, zName); + if( pOther ){ + assert( pOther!=&aDef[i] && pOther->pNext!=&aDef[i] ); + aDef[i].pNext = pOther->pNext; + pOther->pNext = &aDef[i]; + }else{ + aDef[i].pNext = 0; + aDef[i].u.pHash = sqlite3BuiltinFunctions.a[h]; + sqlite3BuiltinFunctions.a[h] = &aDef[i]; + } + } +} + + + +/* +** Locate a user function given a name, a number of arguments and a flag +** indicating whether the function prefers UTF-16 over UTF-8. Return a +** pointer to the FuncDef structure that defines that function, or return +** NULL if the function does not exist. +** +** If the createFlag argument is true, then a new (blank) FuncDef +** structure is created and liked into the "db" structure if a +** no matching function previously existed. +** +** If nArg is -2, then the first valid function found is returned. A +** function is valid if xSFunc is non-zero. The nArg==(-2) +** case is used to see if zName is a valid function name for some number +** of arguments. If nArg is -2, then createFlag must be 0. +** +** If createFlag is false, then a function with the required name and +** number of arguments may be returned even if the eTextRep flag does not +** match that requested. +*/ +FuncDef *sqlite3FindFunction( + sqlite3 *db, /* An open database */ + const char *zName, /* Name of the function. zero-terminated */ + int nArg, /* Number of arguments. -1 means any number */ + u8 enc, /* Preferred text encoding */ + u8 createFlag /* Create new entry if true and does not otherwise exist */ +){ + FuncDef *p; /* Iterator variable */ + FuncDef *pBest = 0; /* Best match found so far */ + int bestScore = 0; /* Score of best match */ + int h; /* Hash value */ + int nName; /* Length of the name */ + + assert( nArg>=(-2) ); + assert( nArg>=(-1) || createFlag==0 ); + nName = sqlite3Strlen30(zName); + + /* First search for a match amongst the application-defined functions. + */ + p = (FuncDef*)sqlite3HashFind(&db->aFunc, zName); + while( p ){ + int score = matchQuality(p, nArg, enc); + if( score>bestScore ){ + pBest = p; + bestScore = score; + } + p = p->pNext; + } + + /* If no match is found, search the built-in functions. + ** + ** If the DBFLAG_PreferBuiltin flag is set, then search the built-in + ** functions even if a prior app-defined function was found. And give + ** priority to built-in functions. + ** + ** Except, if createFlag is true, that means that we are trying to + ** install a new function. Whatever FuncDef structure is returned it will + ** have fields overwritten with new information appropriate for the + ** new function. But the FuncDefs for built-in functions are read-only. + ** So we must not search for built-ins when creating a new function. + */ + if( !createFlag && (pBest==0 || (db->mDbFlags & DBFLAG_PreferBuiltin)!=0) ){ + bestScore = 0; + h = SQLITE_FUNC_HASH(sqlite3UpperToLower[(u8)zName[0]], nName); + p = sqlite3FunctionSearch(h, zName); + while( p ){ + int score = matchQuality(p, nArg, enc); + if( score>bestScore ){ + pBest = p; + bestScore = score; + } + p = p->pNext; + } + } + + /* If the createFlag parameter is true and the search did not reveal an + ** exact match for the name, number of arguments and encoding, then add a + ** new entry to the hash table and return it. + */ + if( createFlag && bestScore<FUNC_PERFECT_MATCH && + (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){ + FuncDef *pOther; + u8 *z; + pBest->zName = (const char*)&pBest[1]; + pBest->nArg = (u16)nArg; + pBest->funcFlags = enc; + memcpy((char*)&pBest[1], zName, nName+1); + for(z=(u8*)pBest->zName; *z; z++) *z = sqlite3UpperToLower[*z]; + pOther = (FuncDef*)sqlite3HashInsert(&db->aFunc, pBest->zName, pBest); + if( pOther==pBest ){ + sqlite3DbFree(db, pBest); + sqlite3OomFault(db); + return 0; + }else{ + pBest->pNext = pOther; + } + } + + if( pBest && (pBest->xSFunc || createFlag) ){ + return pBest; + } + return 0; +} + +/* +** Free all resources held by the schema structure. The void* argument points +** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the +** pointer itself, it just cleans up subsidiary resources (i.e. the contents +** of the schema hash tables). +** +** The Schema.cache_size variable is not cleared. +*/ +void sqlite3SchemaClear(void *p){ + Hash temp1; + Hash temp2; + HashElem *pElem; + Schema *pSchema = (Schema *)p; + sqlite3 xdb; + + memset(&xdb, 0, sizeof(xdb)); + temp1 = pSchema->tblHash; + temp2 = pSchema->trigHash; + sqlite3HashInit(&pSchema->trigHash); + sqlite3HashClear(&pSchema->idxHash); + for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){ + sqlite3DeleteTrigger(&xdb, (Trigger*)sqliteHashData(pElem)); + } + sqlite3HashClear(&temp2); + sqlite3HashInit(&pSchema->tblHash); + for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){ + Table *pTab = sqliteHashData(pElem); + sqlite3DeleteTable(&xdb, pTab); + } + sqlite3HashClear(&temp1); + sqlite3HashClear(&pSchema->fkeyHash); + pSchema->pSeqTab = 0; + if( pSchema->schemaFlags & DB_SchemaLoaded ){ + pSchema->iGeneration++; + } + pSchema->schemaFlags &= ~(DB_SchemaLoaded|DB_ResetWanted); +} + +/* +** Find and return the schema associated with a BTree. Create +** a new one if necessary. +*/ +Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){ + Schema * p; + if( pBt ){ + p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear); + }else{ + p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema)); + } + if( !p ){ + sqlite3OomFault(db); + }else if ( 0==p->file_format ){ + sqlite3HashInit(&p->tblHash); + sqlite3HashInit(&p->idxHash); + sqlite3HashInit(&p->trigHash); + sqlite3HashInit(&p->fkeyHash); + p->enc = SQLITE_UTF8; + } + return p; +} |