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,v 1.32 2008/10/10 17:41:29 drh Exp $

    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 static void callCollNeeded(sqlite3 *db, const char *zName, int nName){

    27   assert( !db->xCollNeeded || !db->xCollNeeded16 );

    28   if( nName<0 ) nName = sqlite3Strlen(db, zName);

    29   if( db->xCollNeeded ){

    30     char *zExternal = sqlite3DbStrNDup(db, zName, nName);

    31     if( !zExternal ) return;

    32     db->xCollNeeded(db->pCollNeededArg, db, (int)ENC(db), zExternal);

    33     sqlite3DbFree(db, zExternal);

    34   }

    35 #ifndef SQLITE_OMIT_UTF16

    36   if( db->xCollNeeded16 ){

    37     char const *zExternal;

    38     sqlite3_value *pTmp = sqlite3ValueNew(db);

    39     sqlite3ValueSetStr(pTmp, nName, zName, SQLITE_UTF8, SQLITE_STATIC);

    40     zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);

    41     if( zExternal ){

    42       db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);

    43     }

    44     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 static int synthCollSeq(sqlite3 *db, CollSeq *pColl){

    57   CollSeq *pColl2;

    58   char *z = pColl->zName;

    59   int n = strlen(z);

    60   int i;

    61   static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };

    62   for(i=0; i<3; i++){

    63     pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, n, 0);

    64     if( pColl2->xCmp!=0 ){

    65       memcpy(pColl, pColl2, sizeof(CollSeq));

    66       pColl->xDel = 0;         /* Do not copy the destructor */

    67       return SQLITE_OK;

    68     }

    69   }

    70   return SQLITE_ERROR;

    71 }

    72 

    73 /*

    74 ** This function is responsible for invoking the collation factory callback

    75 ** or substituting a collation sequence of a different encoding when the

    76 ** requested collation sequence is not available in the database native

    77 ** encoding.

    78 ** 

    79 ** If it is not NULL, then pColl must point to the database native encoding 

    80 ** collation sequence with name zName, length nName.

    81 **

    82 ** The return value is either the collation sequence to be used in database

    83 ** db for collation type name zName, length nName, or NULL, if no collation

    84 ** sequence can be found.

    85 */

    86 CollSeq *sqlite3GetCollSeq(

    87   sqlite3* db, 

    88   CollSeq *pColl, 

    89   const char *zName, 

    90   int nName

    91 ){

    92   CollSeq *p;

    93 

    94   p = pColl;

    95   if( !p ){

    96     p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);

    97   }

    98   if( !p || !p->xCmp ){

    99     /* No collation sequence of this type for this encoding is registered.

   100     ** Call the collation factory to see if it can supply us with one.

   101     */

   102     callCollNeeded(db, zName, nName);

   103     p = sqlite3FindCollSeq(db, ENC(db), zName, nName, 0);

   104   }

   105   if( p && !p->xCmp && synthCollSeq(db, p) ){

   106     p = 0;

   107   }

   108   assert( !p || p->xCmp );

   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 */

   123 int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){

   124   if( pColl ){

   125     const char *zName = pColl->zName;

   126     CollSeq *p = sqlite3GetCollSeq(pParse->db, pColl, zName, -1);

   127     if( !p ){

   128       if( pParse->nErr==0 ){

   129         sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);

   130       }

   131       pParse->nErr++;

   132       return SQLITE_ERROR;

   133     }

   134     assert( p==pColl );

   135   }

   136   return SQLITE_OK;

   137 }

   138 

   139 

   140 

   141 /*

   142 ** Locate and return an entry from the db.aCollSeq hash table. If the entry

   143 ** specified by zName and nName is not found and parameter 'create' is

   144 ** true, then create a new entry. Otherwise return NULL.

   145 **

   146 ** Each pointer stored in the sqlite3.aCollSeq hash table contains an

   147 ** array of three CollSeq structures. The first is the collation sequence

   148 ** prefferred for UTF-8, the second UTF-16le, and the third UTF-16be.

   149 **

   150 ** Stored immediately after the three collation sequences is a copy of

   151 ** the collation sequence name. A pointer to this string is stored in

   152 ** each collation sequence structure.

   153 */

   154 static CollSeq *findCollSeqEntry(

   155   sqlite3 *db,

   156   const char *zName,

   157   int nName,

   158   int create

   159 ){

   160   CollSeq *pColl;

   161   if( nName<0 ) nName = sqlite3Strlen(db, zName);

   162   pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);

   163 

   164   if( 0==pColl && create ){

   165     pColl = sqlite3DbMallocZero(db, 3*sizeof(*pColl) + nName + 1 );

   166     if( pColl ){

   167       CollSeq *pDel = 0;

   168       pColl[0].zName = (char*)&pColl[3];

   169       pColl[0].enc = SQLITE_UTF8;

   170       pColl[1].zName = (char*)&pColl[3];

   171       pColl[1].enc = SQLITE_UTF16LE;

   172       pColl[2].zName = (char*)&pColl[3];

   173       pColl[2].enc = SQLITE_UTF16BE;

   174       memcpy(pColl[0].zName, zName, nName);

   175       pColl[0].zName[nName] = 0;

   176       pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl);

   177 

   178       /* If a malloc() failure occured in sqlite3HashInsert(), it will 

   179       ** return the pColl pointer to be deleted (because it wasn't added

   180       ** to the hash table).

   181       */

   182       assert( pDel==0 || pDel==pColl );

   183       if( pDel!=0 ){

   184         db->mallocFailed = 1;

   185         sqlite3DbFree(db, pDel);

   186         pColl = 0;

   187       }

   188     }

   189   }

   190   return pColl;

   191 }

   192 

   193 /*

   194 ** Parameter zName points to a UTF-8 encoded string nName bytes long.

   195 ** Return the CollSeq* pointer for the collation sequence named zName

   196 ** for the encoding 'enc' from the database 'db'.

   197 **

   198 ** If the entry specified is not found and 'create' is true, then create a

   199 ** new entry.  Otherwise return NULL.

   200 **

   201 ** A separate function sqlite3LocateCollSeq() is a wrapper around

   202 ** this routine.  sqlite3LocateCollSeq() invokes the collation factory

   203 ** if necessary and generates an error message if the collating sequence

   204 ** cannot be found.

   205 */

   206 CollSeq *sqlite3FindCollSeq(

   207   sqlite3 *db,

   208   u8 enc,

   209   const char *zName,

   210   int nName,

   211   int create

   212 ){

   213   CollSeq *pColl;

   214   if( zName ){

   215     pColl = findCollSeqEntry(db, zName, nName, create);

   216   }else{

   217     pColl = db->pDfltColl;

   218   }

   219   assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );

   220   assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );

   221   if( pColl ) pColl += enc-1;

   222   return pColl;

   223 }

   224 

   225 /* During the search for the best function definition, this procedure

   226 ** is called to test how well the function passed as the first argument

   227 ** matches the request for a function with nArg arguments in a system

   228 ** that uses encoding enc. The value returned indicates how well the

   229 ** request is matched. A higher value indicates a better match.

   230 **

   231 ** The returned value is always between 1 and 6, as follows:

   232 **

   233 ** 1: A variable arguments function that prefers UTF-8 when a UTF-16

   234 **    encoding is requested, or vice versa.

   235 ** 2: A variable arguments function that uses UTF-16BE when UTF-16LE is

   236 **    requested, or vice versa.

   237 ** 3: A variable arguments function using the same text encoding.

   238 ** 4: A function with the exact number of arguments requested that

   239 **    prefers UTF-8 when a UTF-16 encoding is requested, or vice versa.

   240 ** 5: A function with the exact number of arguments requested that

   241 **    prefers UTF-16LE when UTF-16BE is requested, or vice versa.

   242 ** 6: An exact match.

   243 **

   244 */

   245 static int matchQuality(FuncDef *p, int nArg, u8 enc){

   246   int match = 0;

   247   if( p->nArg==-1 || p->nArg==nArg || nArg==-1 ){

   248     match = 1;

   249     if( p->nArg==nArg || nArg==-1 ){

   250       match = 4;

   251     }

   252     if( enc==p->iPrefEnc ){

   253       match += 2;

   254     }

   255     else if( (enc==SQLITE_UTF16LE && p->iPrefEnc==SQLITE_UTF16BE) ||

   256              (enc==SQLITE_UTF16BE && p->iPrefEnc==SQLITE_UTF16LE) ){

   257       match += 1;

   258     }

   259   }

   260   return match;

   261 }

   262 

   263 /*

   264 ** Search a FuncDefHash for a function with the given name.  Return

   265 ** a pointer to the matching FuncDef if found, or 0 if there is no match.

   266 */

   267 static FuncDef *functionSearch(

   268   FuncDefHash *pHash,  /* Hash table to search */

   269   int h,               /* Hash of the name */

   270   const char *zFunc,   /* Name of function */

   271   int nFunc            /* Number of bytes in zFunc */

   272 ){

   273   FuncDef *p;

   274   for(p=pHash->a[h]; p; p=p->pHash){

   275     if( sqlite3StrNICmp(p->zName, zFunc, nFunc)==0 && p->zName[nFunc]==0 ){

   276       return p;

   277     }

   278   }

   279   return 0;

   280 }

   281 

   282 /*

   283 ** Insert a new FuncDef into a FuncDefHash hash table.

   284 */

   285 void sqlite3FuncDefInsert(

   286   FuncDefHash *pHash,  /* The hash table into which to insert */

   287   FuncDef *pDef        /* The function definition to insert */

   288 ){

   289   FuncDef *pOther;

   290   int nName = strlen(pDef->zName);

   291   u8 c1 = (u8)pDef->zName[0];

   292   int h = (sqlite3UpperToLower[c1] + nName) % ArraySize(pHash->a);

   293   pOther = functionSearch(pHash, h, pDef->zName, nName);

   294   if( pOther ){

   295     pDef->pNext = pOther->pNext;

   296     pOther->pNext = pDef;

   297   }else{

   298     pDef->pNext = 0;

   299     pDef->pHash = pHash->a[h];

   300     pHash->a[h] = pDef;

   301   }

   302 }

   303   

   304   

   305 

   306 /*

   307 ** Locate a user function given a name, a number of arguments and a flag

   308 ** indicating whether the function prefers UTF-16 over UTF-8.  Return a

   309 ** pointer to the FuncDef structure that defines that function, or return

   310 ** NULL if the function does not exist.

   311 **

   312 ** If the createFlag argument is true, then a new (blank) FuncDef

   313 ** structure is created and liked into the "db" structure if a

   314 ** no matching function previously existed.  When createFlag is true

   315 ** and the nArg parameter is -1, then only a function that accepts

   316 ** any number of arguments will be returned.

   317 **

   318 ** If createFlag is false and nArg is -1, then the first valid

   319 ** function found is returned.  A function is valid if either xFunc

   320 ** or xStep is non-zero.

   321 **

   322 ** If createFlag is false, then a function with the required name and

   323 ** number of arguments may be returned even if the eTextRep flag does not

   324 ** match that requested.

   325 */

   326 FuncDef *sqlite3FindFunction(

   327   sqlite3 *db,       /* An open database */

   328   const char *zName, /* Name of the function.  Not null-terminated */

   329   int nName,         /* Number of characters in the name */

   330   int nArg,          /* Number of arguments.  -1 means any number */

   331   u8 enc,            /* Preferred text encoding */

   332   int createFlag     /* Create new entry if true and does not otherwise exist */

   333 ){

   334   FuncDef *p;         /* Iterator variable */

   335   FuncDef *pBest = 0; /* Best match found so far */

   336   int bestScore = 0;  /* Score of best match */

   337   int h;              /* Hash value */

   338 

   339 

   340   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );

   341   if( nArg<-1 ) nArg = -1;

   342   h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a);

   343 

   344   /* First search for a match amongst the application-defined functions.

   345   */

   346   p = functionSearch(&db->aFunc, h, zName, nName);

   347   while( p ){

   348     int score = matchQuality(p, nArg, enc);

   349     if( score>bestScore ){

   350       pBest = p;

   351       bestScore = score;

   352     }

   353     p = p->pNext;

   354   }

   355 

   356   /* If no match is found, search the built-in functions.

   357   **

   358   ** Except, if createFlag is true, that means that we are trying to

   359   ** install a new function.  Whatever FuncDef structure is returned will

   360   ** have fields overwritten with new information appropriate for the

   361   ** new function.  But the FuncDefs for built-in functions are read-only.

   362   ** So we must not search for built-ins when creating a new function.

   363   */ 

   364   if( !createFlag && !pBest ){

   365     FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);

   366     p = functionSearch(pHash, h, zName, nName);

   367     while( p ){

   368       int score = matchQuality(p, nArg, enc);

   369       if( score>bestScore ){

   370         pBest = p;

   371         bestScore = score;

   372       }

   373       p = p->pNext;

   374     }

   375   }

   376 

   377   /* If the createFlag parameter is true and the search did not reveal an

   378   ** exact match for the name, number of arguments and encoding, then add a

   379   ** new entry to the hash table and return it.

   380   */

   381   if( createFlag && (bestScore<6 || pBest->nArg!=nArg) && 

   382       (pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){

   383     pBest->zName = (char *)&pBest[1];

   384     pBest->nArg = nArg;

   385     pBest->iPrefEnc = enc;

   386     memcpy(pBest->zName, zName, nName);

   387     pBest->zName[nName] = 0;

   388     sqlite3FuncDefInsert(&db->aFunc, pBest);

   389   }

   390 

   391   if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){

   392     return pBest;

   393   }

   394   return 0;

   395 }

   396 

   397 /*

   398 ** Free all resources held by the schema structure. The void* argument points

   399 ** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the 

   400 ** pointer itself, it just cleans up subsiduary resources (i.e. the contents

   401 ** of the schema hash tables).

   402 **

   403 ** The Schema.cache_size variable is not cleared.

   404 */

   405 void sqlite3SchemaFree(void *p){

   406   Hash temp1;

   407   Hash temp2;

   408   HashElem *pElem;

   409   Schema *pSchema = (Schema *)p;

   410 

   411   temp1 = pSchema->tblHash;

   412   temp2 = pSchema->trigHash;

   413   sqlite3HashInit(&pSchema->trigHash, 0);

   414   sqlite3HashClear(&pSchema->aFKey);

   415   sqlite3HashClear(&pSchema->idxHash);

   416   for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){

   417     sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));

   418   }

   419   sqlite3HashClear(&temp2);

   420   sqlite3HashInit(&pSchema->tblHash, 0);

   421   for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){

   422     Table *pTab = sqliteHashData(pElem);

   423     sqlite3DeleteTable(pTab);

   424   }

   425   sqlite3HashClear(&temp1);

   426   pSchema->pSeqTab = 0;

   427   pSchema->flags &= ~DB_SchemaLoaded;

   428 }

   429 

   430 /*

   431 ** Find and return the schema associated with a BTree.  Create

   432 ** a new one if necessary.

   433 */

   434 Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){

   435   Schema * p;

   436   if( pBt ){

   437     p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaFree);

   438   }else{

   439     p = (Schema *)sqlite3MallocZero(sizeof(Schema));

   440   }

   441   if( !p ){

   442     db->mallocFailed = 1;

   443   }else if ( 0==p->file_format ){

   444     sqlite3HashInit(&p->tblHash, 0);

   445     sqlite3HashInit(&p->idxHash, 0);

   446     sqlite3HashInit(&p->trigHash, 0);

   447     sqlite3HashInit(&p->aFKey, 1);

   448     p->enc = SQLITE_UTF8;

   449   }

   450   return p;

   451 }