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-/*
-** 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 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);
- }
- return p;
-}
-
-/*
-** 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 ){
- 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);
- pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1);
- 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);
- pColl[0].zName[nName] = 0;
- 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 ){
- db->mallocFailed = 1;
- 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,
- u8 enc,
- const char *zName,
- int create
-){
- CollSeq *pColl;
- if( zName ){
- pColl = findCollSeqEntry(db, zName, create);
- }else{
- pColl = db->pDfltColl;
- }
- assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
- assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );
- if( pColl ) pColl += enc-1;
- 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 xStep or xFunc is
-** a perfect match and any function with both xStep and xFunc 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;
-
- /* nArg of -2 is a special case */
- if( nArg==(-2) ) return (p->xFunc==0 && p->xStep==0) ? 0 : FUNC_PERFECT_MATCH;
-
- /* Wrong number of arguments means "no match" */
- if( p->nArg!=nArg && 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.
-*/
-static FuncDef *functionSearch(
- FuncDefHash *pHash, /* Hash table to search */
- int h, /* Hash of the name */
- const char *zFunc, /* Name of function */
- int nFunc /* Number of bytes in zFunc */
-){
- FuncDef *p;
- for(p=pHash->a[h]; p; p=p->pHash){
- if( sqlite3StrNICmp(p->zName, zFunc, nFunc)==0 && p->zName[nFunc]==0 ){
- return p;
- }
- }
- return 0;
-}
-
-/*
-** Insert a new FuncDef into a FuncDefHash hash table.
-*/
-void sqlite3FuncDefInsert(
- FuncDefHash *pHash, /* The hash table into which to insert */
- FuncDef *pDef /* The function definition to insert */
-){
- FuncDef *pOther;
- int nName = sqlite3Strlen30(pDef->zName);
- u8 c1 = (u8)pDef->zName[0];
- int h = (sqlite3UpperToLower[c1] + nName) % ArraySize(pHash->a);
- pOther = functionSearch(pHash, h, pDef->zName, nName);
- if( pOther ){
- assert( pOther!=pDef && pOther->pNext!=pDef );
- pDef->pNext = pOther->pNext;
- pOther->pNext = pDef;
- }else{
- pDef->pNext = 0;
- pDef->pHash = pHash->a[h];
- pHash->a[h] = pDef;
- }
-}
-
-
-
-/*
-** 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 either xFunc or xStep 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. Not null-terminated */
- int nName, /* Number of characters in the name */
- 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 */
-
- assert( nArg>=(-2) );
- assert( nArg>=(-1) || createFlag==0 );
- h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a);
-
- /* First search for a match amongst the application-defined functions.
- */
- p = functionSearch(&db->aFunc, h, zName, nName);
- 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 SQLITE_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->flags & SQLITE_PreferBuiltin)!=0) ){
- FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);
- bestScore = 0;
- p = functionSearch(pHash, h, zName, nName);
- 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 ){
- pBest->zName = (char *)&pBest[1];
- pBest->nArg = (u16)nArg;
- pBest->funcFlags = enc;
- memcpy(pBest->zName, zName, nName);
- pBest->zName[nName] = 0;
- sqlite3FuncDefInsert(&db->aFunc, pBest);
- }
-
- if( pBest && (pBest->xStep || pBest->xFunc || 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;
-
- temp1 = pSchema->tblHash;
- temp2 = pSchema->trigHash;
- sqlite3HashInit(&pSchema->trigHash);
- sqlite3HashClear(&pSchema->idxHash);
- for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){
- sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));
- }
- sqlite3HashClear(&temp2);
- sqlite3HashInit(&pSchema->tblHash);
- for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){
- Table *pTab = sqliteHashData(pElem);
- sqlite3DeleteTable(0, pTab);
- }
- sqlite3HashClear(&temp1);
- sqlite3HashClear(&pSchema->fkeyHash);
- pSchema->pSeqTab = 0;
- if( pSchema->schemaFlags & DB_SchemaLoaded ){
- pSchema->iGeneration++;
- pSchema->schemaFlags &= ~DB_SchemaLoaded;
- }
-}
-
-/*
-** 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 ){
- db->mallocFailed = 1;
- }else if ( 0==p->file_format ){
- sqlite3HashInit(&p->tblHash);
- sqlite3HashInit(&p->idxHash);
- sqlite3HashInit(&p->trigHash);
- sqlite3HashInit(&p->fkeyHash);
- p->enc = SQLITE_UTF8;
- }
- return p;
-}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.