/* ** This function is exactly the same as sqlite3_create_function(), except ** that it is designed to be called by internal code. The difference is ** that if a malloc() fails in sqlite3_create_function(), an error code ** is returned and the mallocFailed flag cleared. */ int sqlite3CreateFunc( sqlite3 *db, const char *zFunctionName, int nArg, int enc, void *pUserData, void (*xFunc)(sqlite3_context*,int,sqlite3_value **), void (*xStep)(sqlite3_context*,int,sqlite3_value **), void (*xFinal)(sqlite3_context*) ){ FuncDef *p; int nName; assert( sqlite3_mutex_held(db->mutex) ); if( sqlite3SafetyCheck(db) ){ return SQLITE_MISUSE; } if( zFunctionName==0 || (xFunc && (xFinal || xStep)) || (!xFunc && (xFinal && !xStep)) || (!xFunc && (!xFinal && xStep)) || (nArg<-1 || nArg>127) || (255<(nName = strlen(zFunctionName))) ){ sqlite3Error(db, SQLITE_ERROR, "bad parameters"); return SQLITE_ERROR; } #ifndef SQLITE_OMIT_UTF16 /* If SQLITE_UTF16 is specified as the encoding type, transform this ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally. ** ** If SQLITE_ANY is specified, add three versions of the function ** to the hash table. */ if( enc==SQLITE_UTF16 ){ enc = SQLITE_UTF16NATIVE; }else if( enc==SQLITE_ANY ){ int rc; rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF8, pUserData, xFunc, xStep, xFinal); if( rc==SQLITE_OK ){ rc = sqlite3CreateFunc(db, zFunctionName, nArg, SQLITE_UTF16LE, pUserData, xFunc, xStep, xFinal); } if( rc!=SQLITE_OK ){ return rc; } enc = SQLITE_UTF16BE; } #else enc = SQLITE_UTF8; #endif /* Check if an existing function is being overridden or deleted. If so, ** and there are active VMs, then return SQLITE_BUSY. If a function ** is being overridden/deleted but there are no active VMs, allow the ** operation to continue but invalidate all precompiled statements. */ p = sqlite3FindFunction(db, zFunctionName, nName, nArg, enc, 0); if( p && p->iPrefEnc==enc && p->nArg==nArg ){ if( db->activeVdbeCnt ){ sqlite3Error(db, SQLITE_BUSY, "Unable to delete/modify user-function due to active statements"); assert( !db->mallocFailed ); return SQLITE_BUSY; }else{ sqlite3ExpirePreparedStatements(db); } } p = sqlite3FindFunction(db, zFunctionName, nName, nArg, enc, 1); assert(p || db->mallocFailed); if( !p ){ return SQLITE_NOMEM; } p->flags = 0; p->xFunc = xFunc; p->xStep = xStep; p->xFinalize = xFinal; p->pUserData = pUserData; p->nArg = nArg; return SQLITE_OK; }
SQLITE_API void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetInt64(&pCtx->s, iVal); }
void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetZeroBlob(pCtx->pOut, n); }
} /* ** Discard all pages from cache pCache with a page number (key value) ** greater than or equal to iLimit. Any pinned pages that meet this ** criteria are unpinned before they are discarded. ** ** The PCache mutex must be held when this function is called. */ static void pcache1TruncateUnsafe( PCache1 *pCache, /* The cache to truncate */ unsigned int iLimit /* Drop pages with this pgno or larger */ ){ TESTONLY( unsigned int nPage = 0; ) /* To assert pCache->nPage is correct */ unsigned int h; assert( sqlite3_mutex_held(pCache->pGroup->mutex) ); for(h=0; h<pCache->nHash; h++){ PgHdr1 **pp = &pCache->apHash[h]; PgHdr1 *pPage; while( (pPage = *pp)!=0 ){ if( pPage->iKey>=iLimit ){ pCache->nPage--; *pp = pPage->pNext; pcache1PinPage(pPage); pcache1FreePage(pPage); }else{ pp = &pPage->pNext; TESTONLY( nPage++; ) } } }
void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); pCtx->isError = SQLITE_ERROR; pCtx->fErrorOrAux = 1; sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT); }
void sqlite3_result_null(sqlite3_context *pCtx){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetNull(pCtx->pOut); }
*/该函数返回至少n字节大小的block,没有则返回null。该函数假设所有必要的互斥锁都上了,所以不安全 static void *memsys3MallocUnsafe(int nByte){ u32 i; u32 nBlock; u32 toFree; assert( sqlite3_mutex_held(mem3.mutex) ); //如果不能加锁,则终止程序 assert( sizeof(Mem3Block)==8 ); //若Mem3Block大小为8,继续往下执行 if( nByte<=12 ){ //给nBlock赋值 nBlock = 2; }else{ nBlock = (nByte + 11)/8; } assert( nBlock>=2 ); /* STEP 1: ** Look for an entry of the correct size in either the small ** chunk table or in the large chunk hash table. This is ** successful most of the time (about 9 times out of 10). */ //首先在小chunk或者大chunk中寻找正确大小块的入口,一般都会成功 if( nBlock <= MX_SMALL ){ //nBlock小于MX_SMALL,则在小chunk中找 i = mem3.aiSmall[nBlock-2]; if( i>0 ){ memsys3UnlinkFromList(i, &mem3.aiSmall[nBlock-2]); return memsys3Checkout(i, nBlock); //返回找到的满足的chunk } }else{ //若nBlock大于MX_SMALL,则在大chunk中找 int hash = nBlock % N_HASH; for(i=mem3.aiHash[hash]; i>0; i=mem3.aPool[i].u.list.next){ if( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ){ memsys3UnlinkFromList(i, &mem3.aiHash[hash]); return memsys3Checkout(i, nBlock); //返回找到的chunk } } } /* STEP 2: ** Try to satisfy the allocation by carving a piece off of the end ** of the master chunk. This step usually works if step 1 fails. */ //尝试从master chunk中分裂出合适的空间,第一步失败才执行 if( mem3.szMaster>=nBlock ){ return memsys3FromMaster(nBlock); //从master chunk中获取chunk } /* STEP 3: ** Loop through the entire memory pool. Coalesce adjacent free ** chunks. Recompute the master chunk as the largest free chunk. ** Then try again to satisfy the allocation by carving a piece off ** of the end of the master chunk. This step happens very ** rarely (we hope!) */遍历整个内存池,合并相邻空闲chunk,重新计算主要的chunk大小,再次尝试从master chunk中分裂出满足分配条件的chunk。前面都不行才执行该步骤。 for(toFree=nBlock*16; toFree<(mem3.nPool*16); toFree *= 2){ //遍历内存池 memsys3OutOfMemory(toFree); //不够分配则释放 if( mem3.iMaster ){ //master chunk存在,将其链接到相应块索引表中 memsys3Link(mem3.iMaster); mem3.iMaster = 0; mem3.szMaster = 0; } for(i=0; i<N_HASH; i++){ memsys3Merge(&mem3.aiHash[i]); //链接相邻空chunk到aiHash中 } for(i=0; i<MX_SMALL-1; i++){ memsys3Merge(&mem3.aiSmall[i]); //链接相邻空chunk到aiSmall中 } if( mem3.szMaster ){ //当前master chunk不为0,则从索引表中断开 memsys3Unlink(mem3.iMaster); if( mem3.szMaster>=nBlock ){ return memsys3FromMaster(nBlock); //返回得到的内存空间 } } } /* If none of the above worked, then we fail. */ return 0; //若上面三步都失败了,那就失败了,返回0 }
/* ** This is the callback routine for the code that initializes the ** database. See sqlite3Init() below for additional information. ** This routine is also called from the OP_ParseSchema opcode of the VDBE. ** ** Each callback contains the following information: ** ** argv[0] = name of thing being created ** argv[1] = root page number for table or index. 0 for trigger or view. ** argv[2] = SQL text for the CREATE statement. ** */ int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){ InitData *pData = (InitData*)pInit; sqlite3 *db = pData->db; int iDb = pData->iDb; assert( argc==3 ); UNUSED_PARAMETER2(NotUsed, argc); assert( sqlite3_mutex_held(db->mutex) ); DbClearProperty(db, iDb, DB_Empty); if( db->mallocFailed ){ corruptSchema(pData, argv[0], 0); return 1; } assert( iDb>=0 && iDb<db->nDb ); if( argv==0 ) return 0; /* Might happen if EMPTY_RESULT_CALLBACKS are on */ if( argv[1]==0 ){ corruptSchema(pData, argv[0], 0); }else if( argv[2] && argv[2][0] ){ /* Call the parser to process a CREATE TABLE, INDEX or VIEW. ** But because db->init.busy is set to 1, no VDBE code is generated ** or executed. All the parser does is build the internal data ** structures that describe the table, index, or view. */ char *zErr; int rc; assert( db->init.busy ); db->init.iDb = iDb; db->init.newTnum = atoi(argv[1]); db->init.orphanTrigger = 0; rc = sqlite3_exec(db, argv[2], 0, 0, &zErr); db->init.iDb = 0; assert( rc!=SQLITE_OK || zErr==0 ); if( SQLITE_OK!=rc ){ if( db->init.orphanTrigger ){ assert( iDb==1 ); }else{ pData->rc = rc; if( rc==SQLITE_NOMEM ){ db->mallocFailed = 1; }else if( rc!=SQLITE_INTERRUPT && rc!=SQLITE_LOCKED ){ corruptSchema(pData, argv[0], zErr); } } sqlite3DbFree(db, zErr); } }else if( argv[0]==0 ){ corruptSchema(pData, 0, 0); }else{ /* If the SQL column is blank it means this is an index that ** was created to be the PRIMARY KEY or to fulfill a UNIQUE ** constraint for a CREATE TABLE. The index should have already ** been created when we processed the CREATE TABLE. All we have ** to do here is record the root page number for that index. */ Index *pIndex; pIndex = sqlite3FindIndex(db, argv[0], db->aDb[iDb].zName); if( pIndex==0 ){ /* This can occur if there exists an index on a TEMP table which ** has the same name as another index on a permanent index. Since ** the permanent table is hidden by the TEMP table, we can also ** safely ignore the index on the permanent table. */ /* Do Nothing */; }else if( sqlite3GetInt32(argv[1], &pIndex->tnum)==0 ){ corruptSchema(pData, argv[0], "invalid rootpage"); } } return 0; }
} /* ** Discard all pages from cache pCache with a page number (key value) ** greater than or equal to iLimit. Any pinned pages that meet this ** criteria are unpinned before they are discarded. ** ** The global mutex must be held when this function is called. */ static void pcache1TruncateUnsafe( PCache1 *pCache, unsigned int iLimit ){ TESTONLY( unsigned int nPage = 0; ) /* Used to assert pCache->nPage is correct */ unsigned int h; assert( sqlite3_mutex_held(pcache1.mutex) ); for(h=0; h<pCache->nHash; h++){ PgHdr1 **pp = &pCache->apHash[h]; PgHdr1 *pPage; while( (pPage = *pp)!=0 ){ if( pPage->iKey>=iLimit ){ pCache->nPage--; *pp = pPage->pNext; pcache1PinPage(pPage); pcache1FreePage(pPage); }else{ pp = &pPage->pNext; TESTONLY( nPage++; ) } } }
/* ** This routine transforms the internal text encoding used by pMem to ** desiredEnc. It is an error if the string is already of the desired ** encoding, or if *pMem does not contain a string value. */ int sqlite3VdbeMemTranslate(Mem *pMem, u8 desiredEnc){ int len; /* Maximum length of output string in bytes */ unsigned char *zOut; /* Output buffer */ unsigned char *zIn; /* Input iterator */ unsigned char *zTerm; /* End of input */ unsigned char *z; /* Output iterator */ unsigned int c; assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) ); assert( pMem->flags&MEM_Str ); assert( pMem->enc!=desiredEnc ); assert( pMem->enc!=0 ); assert( pMem->n>=0 ); #if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG) { char zBuf[100]; sqlite3VdbeMemPrettyPrint(pMem, zBuf); fprintf(stderr, "INPUT: %s\n", zBuf); } #endif /* If the translation is between UTF-16 little and big endian, then ** all that is required is to swap the byte order. This case is handled ** differently from the others. */ if( pMem->enc!=SQLITE_UTF8 && desiredEnc!=SQLITE_UTF8 ){ u8 temp; int rc; rc = sqlite3VdbeMemMakeWriteable(pMem); if( rc!=SQLITE_OK ){ assert( rc==SQLITE_NOMEM ); return SQLITE_NOMEM; } zIn = (u8*)pMem->z; zTerm = &zIn[pMem->n&~1]; while( zIn<zTerm ){ temp = *zIn; *zIn = *(zIn+1); zIn++; *zIn++ = temp; } pMem->enc = desiredEnc; goto translate_out; } /* Set len to the maximum number of bytes required in the output buffer. */ if( desiredEnc==SQLITE_UTF8 ){ /* When converting from UTF-16, the maximum growth results from ** translating a 2-byte character to a 4-byte UTF-8 character. ** A single byte is required for the output string ** nul-terminator. */ pMem->n &= ~1; len = pMem->n * 2 + 1; }else{ /* When converting from UTF-8 to UTF-16 the maximum growth is caused ** when a 1-byte UTF-8 character is translated into a 2-byte UTF-16 ** character. Two bytes are required in the output buffer for the ** nul-terminator. */ len = pMem->n * 2 + 2; } /* Set zIn to point at the start of the input buffer and zTerm to point 1 ** byte past the end. ** ** Variable zOut is set to point at the output buffer, space obtained ** from sqlite3_malloc(). */ zIn = (u8*)pMem->z; zTerm = &zIn[pMem->n]; zOut = (unsigned char *) sqlite3DbMallocRaw(pMem->db, len); if( !zOut ){ return SQLITE_NOMEM; } z = zOut; if( pMem->enc==SQLITE_UTF8 ){ if( desiredEnc==SQLITE_UTF16LE ){ /* UTF-8 -> UTF-16 Little-endian */ while( zIn<zTerm ){ /* c = sqlite3Utf8Read(zIn, zTerm, (const u8**)&zIn); */ READ_UTF8(zIn, zTerm, c); WRITE_UTF16LE(z, c); } }else{ assert( desiredEnc==SQLITE_UTF16BE ); /* UTF-8 -> UTF-16 Big-endian */ while( zIn<zTerm ){ /* c = sqlite3Utf8Read(zIn, zTerm, (const u8**)&zIn); */ READ_UTF8(zIn, zTerm, c); WRITE_UTF16BE(z, c); } } pMem->n = (int)(z - zOut); *z++ = 0; }else{ assert( desiredEnc==SQLITE_UTF8 ); if( pMem->enc==SQLITE_UTF16LE ){ /* UTF-16 Little-endian -> UTF-8 */ while( zIn<zTerm ){ READ_UTF16LE(zIn, zIn<zTerm, c); WRITE_UTF8(z, c); } }else{ /* UTF-16 Big-endian -> UTF-8 */ while( zIn<zTerm ){ READ_UTF16BE(zIn, zIn<zTerm, c); WRITE_UTF8(z, c); } } pMem->n = (int)(z - zOut); } *z = 0; assert( (pMem->n+(desiredEnc==SQLITE_UTF8?1:2))<=len ); sqlite3VdbeMemRelease(pMem); pMem->flags &= ~(MEM_Static|MEM_Dyn|MEM_Ephem); pMem->enc = desiredEnc; pMem->flags |= (MEM_Term|MEM_Dyn); pMem->z = (char*)zOut; pMem->zMalloc = pMem->z; translate_out: #if defined(TRANSLATE_TRACE) && defined(SQLITE_DEBUG) { char zBuf[100]; sqlite3VdbeMemPrettyPrint(pMem, zBuf); fprintf(stderr, "OUTPUT: %s\n", zBuf); } #endif return SQLITE_OK; }
SQLITE_API void sqlite3_result_zeroblob(sqlite3_context *pCtx, int n){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetZeroBlob(&pCtx->s, n); }
/**************************** sqlite3_result_ ******************************* ** The following routines are used by user-defined functions to specify ** the function result. ** ** The setStrOrError() funtion calls sqlite3VdbeMemSetStr() to store the ** result as a string or blob but if the string or blob is too large, it ** then sets the error code to SQLITE_TOOBIG */ static void setResultStrOrError( sqlite3_context *pCtx, /* Function context */ const char *z, /* String pointer */ int n, /* Bytes in string, or negative */ u8 enc, /* Encoding of z. 0 for BLOBs */ void (*xDel)(void*) /* Destructor function */ ){ if( sqlite3VdbeMemSetStr(&pCtx->s, z, n, enc, xDel)==SQLITE_TOOBIG ){ sqlite3_result_error_toobig(pCtx); } } SQLITE_API void sqlite3_result_blob( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( n>=0 ); assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); setResultStrOrError(pCtx, z, n, 0, xDel); } SQLITE_API void sqlite3_result_double(sqlite3_context *pCtx, double rVal){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetDouble(&pCtx->s, rVal); } SQLITE_API void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); pCtx->isError = SQLITE_ERROR; pCtx->fErrorOrAux = 1; sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF8, SQLITE_TRANSIENT); } #ifndef SQLITE_OMIT_UTF16 SQLITE_API void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); pCtx->isError = SQLITE_ERROR; pCtx->fErrorOrAux = 1; sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT); } #endif SQLITE_API void sqlite3_result_int(sqlite3_context *pCtx, int iVal){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetInt64(&pCtx->s, (i64)iVal); } SQLITE_API void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetInt64(&pCtx->s, iVal); } SQLITE_API void sqlite3_result_null(sqlite3_context *pCtx){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetNull(&pCtx->s); } SQLITE_API void sqlite3_result_text( sqlite3_context *pCtx, const char *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel); } #ifndef SQLITE_OMIT_UTF16 SQLITE_API void sqlite3_result_text16( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel); } SQLITE_API void sqlite3_result_text16be( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel); } SQLITE_API void sqlite3_result_text16le( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel); } #endif /* SQLITE_OMIT_UTF16 */ SQLITE_API void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemCopy(&pCtx->s, pValue); }
SQLITE_API void sqlite3_result_null(sqlite3_context *pCtx){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetNull(&pCtx->s); }
/* ** Attempt to read the database schema and initialize internal ** data structures for a single database file. The index of the ** database file is given by iDb. iDb==0 is used for the main ** database. iDb==1 should never be used. iDb>=2 is used for ** auxiliary databases. Return one of the SQLITE_ error codes to ** indicate success or failure. */ static int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){ int rc; int i; int size; Table *pTab; Db *pDb; char const *azArg[4]; int meta[5]; InitData initData; char const *zMasterSchema; char const *zMasterName = SCHEMA_TABLE(iDb); int openedTransaction = 0; /* ** The master database table has a structure like this */ static const char master_schema[] = "CREATE TABLE sqlite_master(\n" " type text,\n" " name text,\n" " tbl_name text,\n" " rootpage integer,\n" " sql text\n" ")" ; #ifndef SQLITE_OMIT_TEMPDB static const char temp_master_schema[] = "CREATE TEMP TABLE sqlite_temp_master(\n" " type text,\n" " name text,\n" " tbl_name text,\n" " rootpage integer,\n" " sql text\n" ")" ; #else #define temp_master_schema 0 #endif assert( iDb>=0 && iDb<db->nDb ); assert( db->aDb[iDb].pSchema ); assert( sqlite3_mutex_held(db->mutex) ); assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) ); /* zMasterSchema and zInitScript are set to point at the master schema ** and initialisation script appropriate for the database being ** initialised. zMasterName is the name of the master table. */ if( !OMIT_TEMPDB && iDb==1 ){ zMasterSchema = temp_master_schema; }else{ zMasterSchema = master_schema; } zMasterName = SCHEMA_TABLE(iDb); /* Construct the schema tables. */ azArg[0] = zMasterName; azArg[1] = "1"; azArg[2] = zMasterSchema; azArg[3] = 0; initData.db = db; initData.iDb = iDb; initData.rc = SQLITE_OK; initData.pzErrMsg = pzErrMsg; (void)sqlite3SafetyOff(db); sqlite3InitCallback(&initData, 3, (char **)azArg, 0); (void)sqlite3SafetyOn(db); if( initData.rc ){ rc = initData.rc; goto error_out; } pTab = sqlite3FindTable(db, zMasterName, db->aDb[iDb].zName); if( ALWAYS(pTab) ){ pTab->tabFlags |= TF_Readonly; } /* Create a cursor to hold the database open */ pDb = &db->aDb[iDb]; if( pDb->pBt==0 ){ if( !OMIT_TEMPDB && ALWAYS(iDb==1) ){ DbSetProperty(db, 1, DB_SchemaLoaded); } return SQLITE_OK; } /* If there is not already a read-only (or read-write) transaction opened ** on the b-tree database, open one now. If a transaction is opened, it ** will be closed before this function returns. */ sqlite3BtreeEnter(pDb->pBt); if( !sqlite3BtreeIsInReadTrans(pDb->pBt) ){ rc = sqlite3BtreeBeginTrans(pDb->pBt, 0); if( rc!=SQLITE_OK ){ sqlite3SetString(pzErrMsg, db, "%s", sqlite3ErrStr(rc)); goto initone_error_out; } openedTransaction = 1; } /* Get the database meta information. ** ** Meta values are as follows: ** meta[0] Schema cookie. Changes with each schema change. ** meta[1] File format of schema layer. ** meta[2] Size of the page cache. ** meta[3] Largest rootpage (auto/incr_vacuum mode) ** meta[4] Db text encoding. 1:UTF-8 2:UTF-16LE 3:UTF-16BE ** meta[5] User version ** meta[6] Incremental vacuum mode ** meta[7] unused ** meta[8] unused ** meta[9] unused ** ** Note: The #defined SQLITE_UTF* symbols in sqliteInt.h correspond to ** the possible values of meta[4]. */ for(i=0; i<ArraySize(meta); i++){ sqlite3BtreeGetMeta(pDb->pBt, i+1, (u32 *)&meta[i]); } pDb->pSchema->schema_cookie = meta[BTREE_SCHEMA_VERSION-1]; /* If opening a non-empty database, check the text encoding. For the ** main database, set sqlite3.enc to the encoding of the main database. ** For an attached db, it is an error if the encoding is not the same ** as sqlite3.enc. */ if( meta[BTREE_TEXT_ENCODING-1] ){ /* text encoding */ if( iDb==0 ){ u8 encoding; /* If opening the main database, set ENC(db). */ encoding = (u8)meta[BTREE_TEXT_ENCODING-1] & 3; if( encoding==0 ) encoding = SQLITE_UTF8; ENC(db) = encoding; db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, "BINARY", 0); }else{ /* If opening an attached database, the encoding much match ENC(db) */ if( meta[BTREE_TEXT_ENCODING-1]!=ENC(db) ){ sqlite3SetString(pzErrMsg, db, "attached databases must use the same" " text encoding as main database"); rc = SQLITE_ERROR; goto initone_error_out; } } }else{ DbSetProperty(db, iDb, DB_Empty); } pDb->pSchema->enc = ENC(db); if( pDb->pSchema->cache_size==0 ){ size = meta[BTREE_DEFAULT_CACHE_SIZE-1]; if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; } if( size<0 ) size = -size; pDb->pSchema->cache_size = size; sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size); } /* ** file_format==1 Version 3.0.0. ** file_format==2 Version 3.1.3. // ALTER TABLE ADD COLUMN ** file_format==3 Version 3.1.4. // ditto but with non-NULL defaults ** file_format==4 Version 3.3.0. // DESC indices. Boolean constants */ pDb->pSchema->file_format = (u8)meta[BTREE_FILE_FORMAT-1]; if( pDb->pSchema->file_format==0 ){ pDb->pSchema->file_format = 1; } if( pDb->pSchema->file_format>SQLITE_MAX_FILE_FORMAT ){ sqlite3SetString(pzErrMsg, db, "unsupported file format"); rc = SQLITE_ERROR; goto initone_error_out; } /* Ticket #2804: When we open a database in the newer file format, ** clear the legacy_file_format pragma flag so that a VACUUM will ** not downgrade the database and thus invalidate any descending ** indices that the user might have created. */ if( iDb==0 && meta[BTREE_FILE_FORMAT-1]>=4 ){ db->flags &= ~SQLITE_LegacyFileFmt; } /* Read the schema information out of the schema tables */ assert( db->init.busy ); { char *zSql; zSql = sqlite3MPrintf(db, "SELECT name, rootpage, sql FROM '%q'.%s", db->aDb[iDb].zName, zMasterName); (void)sqlite3SafetyOff(db); #ifndef SQLITE_OMIT_AUTHORIZATION { int (*xAuth)(void*,int,const char*,const char*,const char*,const char*); xAuth = db->xAuth; db->xAuth = 0; #endif rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0); #ifndef SQLITE_OMIT_AUTHORIZATION db->xAuth = xAuth; } #endif if( rc==SQLITE_OK ) rc = initData.rc; (void)sqlite3SafetyOn(db); sqlite3DbFree(db, zSql); #ifndef SQLITE_OMIT_ANALYZE if( rc==SQLITE_OK ){ sqlite3AnalysisLoad(db, iDb); } #endif } if( db->mallocFailed ){ rc = SQLITE_NOMEM; sqlite3ResetInternalSchema(db, 0); } if( rc==SQLITE_OK || (db->flags&SQLITE_RecoveryMode)){ /* Black magic: If the SQLITE_RecoveryMode flag is set, then consider ** the schema loaded, even if errors occurred. In this situation the ** current sqlite3_prepare() operation will fail, but the following one ** will attempt to compile the supplied statement against whatever subset ** of the schema was loaded before the error occurred. The primary ** purpose of this is to allow access to the sqlite_master table ** even when its contents have been corrupted. */ DbSetProperty(db, iDb, DB_SchemaLoaded); rc = SQLITE_OK; } /* Jump here for an error that occurs after successfully allocating ** curMain and calling sqlite3BtreeEnter(). For an error that occurs ** before that point, jump to error_out. */ initone_error_out: if( openedTransaction ){ sqlite3BtreeCommit(pDb->pBt); } sqlite3BtreeLeave(pDb->pBt); error_out: if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){ db->mallocFailed = 1; } return rc; }
void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); pCtx->isError = SQLITE_ERROR; sqlite3VdbeMemSetStr(&pCtx->s, z, n, SQLITE_UTF8, SQLITE_TRANSIENT); }
/* ** Compile the UTF-8 encoded SQL statement zSql into a statement handle. */ static int sqlite3Prepare( sqlite3 *db, /* Database handle. */ const char *zSql, /* UTF-8 encoded SQL statement. */ int nBytes, /* Length of zSql in bytes. */ int saveSqlFlag, /* True to copy SQL text into the sqlite3_stmt */ Vdbe *pReprepare, /* VM being reprepared */ sqlite3_stmt **ppStmt, /* OUT: A pointer to the prepared statement */ const char **pzTail /* OUT: End of parsed string */ ){ Parse *pParse; /* Parsing context */ char *zErrMsg = 0; /* Error message */ int rc = SQLITE_OK; /* Result code */ int i; /* Loop counter */ /* Allocate the parsing context */ pParse = sqlite3StackAllocZero(db, sizeof(*pParse)); if( pParse==0 ){ rc = SQLITE_NOMEM; goto end_prepare; } pParse->pReprepare = pReprepare; if( sqlite3SafetyOn(db) ){ rc = SQLITE_MISUSE; goto end_prepare; } assert( ppStmt && *ppStmt==0 ); assert( !db->mallocFailed ); assert( sqlite3_mutex_held(db->mutex) ); /* Check to verify that it is possible to get a read lock on all ** database schemas. The inability to get a read lock indicates that ** some other database connection is holding a write-lock, which in ** turn means that the other connection has made uncommitted changes ** to the schema. ** ** Were we to proceed and prepare the statement against the uncommitted ** schema changes and if those schema changes are subsequently rolled ** back and different changes are made in their place, then when this ** prepared statement goes to run the schema cookie would fail to detect ** the schema change. Disaster would follow. ** ** This thread is currently holding mutexes on all Btrees (because ** of the sqlite3BtreeEnterAll() in sqlite3LockAndPrepare()) so it ** is not possible for another thread to start a new schema change ** while this routine is running. Hence, we do not need to hold ** locks on the schema, we just need to make sure nobody else is ** holding them. ** ** Note that setting READ_UNCOMMITTED overrides most lock detection, ** but it does *not* override schema lock detection, so this all still ** works even if READ_UNCOMMITTED is set. */ for(i=0; i<db->nDb; i++) { Btree *pBt = db->aDb[i].pBt; if( pBt ){ assert( sqlite3BtreeHoldsMutex(pBt) ); rc = sqlite3BtreeSchemaLocked(pBt); if( rc ){ const char *zDb = db->aDb[i].zName; sqlite3Error(db, rc, "database schema is locked: %s", zDb); (void)sqlite3SafetyOff(db); testcase( db->flags & SQLITE_ReadUncommitted ); goto end_prepare; } } } sqlite3VtabUnlockList(db); pParse->db = db; if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){ char *zSqlCopy; int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH]; testcase( nBytes==mxLen ); testcase( nBytes==mxLen+1 ); if( nBytes>mxLen ){ sqlite3Error(db, SQLITE_TOOBIG, "statement too long"); (void)sqlite3SafetyOff(db); rc = sqlite3ApiExit(db, SQLITE_TOOBIG); goto end_prepare; } zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes); if( zSqlCopy ){ sqlite3RunParser(pParse, zSqlCopy, &zErrMsg); sqlite3DbFree(db, zSqlCopy); pParse->zTail = &zSql[pParse->zTail-zSqlCopy]; }else{ pParse->zTail = &zSql[nBytes]; } }else{ sqlite3RunParser(pParse, zSql, &zErrMsg); } if( db->mallocFailed ){ pParse->rc = SQLITE_NOMEM; } if( pParse->rc==SQLITE_DONE ) pParse->rc = SQLITE_OK; if( pParse->checkSchema ){ schemaIsValid(pParse); } if( pParse->rc==SQLITE_SCHEMA ){ sqlite3ResetInternalSchema(db, 0); } if( db->mallocFailed ){ pParse->rc = SQLITE_NOMEM; } if( pzTail ){ *pzTail = pParse->zTail; } rc = pParse->rc; #ifndef SQLITE_OMIT_EXPLAIN if( rc==SQLITE_OK && pParse->pVdbe && pParse->explain ){ static const char * const azColName[] = { "addr", "opcode", "p1", "p2", "p3", "p4", "p5", "comment", "order", "from", "detail" }; int iFirst, mx; if( pParse->explain==2 ){ sqlite3VdbeSetNumCols(pParse->pVdbe, 3); iFirst = 8; mx = 11; }else{ sqlite3VdbeSetNumCols(pParse->pVdbe, 8); iFirst = 0; mx = 8; } for(i=iFirst; i<mx; i++){ sqlite3VdbeSetColName(pParse->pVdbe, i-iFirst, COLNAME_NAME, azColName[i], SQLITE_STATIC); } } #endif if( sqlite3SafetyOff(db) ){ rc = SQLITE_MISUSE; } assert( db->init.busy==0 || saveSqlFlag==0 ); if( db->init.busy==0 ){ Vdbe *pVdbe = pParse->pVdbe; sqlite3VdbeSetSql(pVdbe, zSql, (int)(pParse->zTail-zSql), saveSqlFlag); } if( pParse->pVdbe && (rc!=SQLITE_OK || db->mallocFailed) ){ sqlite3VdbeFinalize(pParse->pVdbe); assert(!(*ppStmt)); }else{ *ppStmt = (sqlite3_stmt*)pParse->pVdbe; } if( zErrMsg ){ sqlite3Error(db, rc, "%s", zErrMsg); sqlite3DbFree(db, zErrMsg); }else{ sqlite3Error(db, rc, 0); } /* Delete any TriggerPrg structures allocated while parsing this statement. */ while( pParse->pTriggerPrg ){ TriggerPrg *pT = pParse->pTriggerPrg; pParse->pTriggerPrg = pT->pNext; sqlite3VdbeProgramDelete(db, pT->pProgram, 0); sqlite3DbFree(db, pT); } end_prepare: sqlite3StackFree(db, pParse); rc = sqlite3ApiExit(db, rc); assert( (rc&db->errMask)==rc ); return rc; }
void sqlite3_result_int(sqlite3_context *pCtx, int iVal){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetInt64(&pCtx->s, (i64)iVal); }
void sqlite3_result_double(sqlite3_context *pCtx, double rVal){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetDouble(pCtx->pOut, rVal); }
/* Force an SQLITE_TOOBIG error. */ void sqlite3_result_error_toobig(sqlite3_context *pCtx){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); pCtx->isError = SQLITE_TOOBIG; sqlite3VdbeMemSetStr(&pCtx->s, "string or blob too big", -1, SQLITE_UTF8, SQLITE_STATIC); }
void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetInt64(pCtx->pOut, iVal); }
/* An SQLITE_NOMEM error. */ void sqlite3_result_error_nomem(sqlite3_context *pCtx){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetNull(&pCtx->s); pCtx->isError = SQLITE_NOMEM; pCtx->s.db->mallocFailed = 1; }
/* noop */ }else{ xDel((void*)p); } if( pCtx ) sqlite3_result_error_toobig(pCtx); return SQLITE_TOOBIG; } void sqlite3_result_blob( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( n>=0 ); assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); setResultStrOrError(pCtx, z, n, 0, xDel); } void sqlite3_result_blob64( sqlite3_context *pCtx, const void *z, sqlite3_uint64 n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); assert( xDel!=SQLITE_DYNAMIC ); if( n>0x7fffffff ){ (void)invokeValueDestructor(z, xDel, pCtx); }else{ setResultStrOrError(pCtx, z, (int)n, 0, xDel); } } void sqlite3_result_double(sqlite3_context *pCtx, double rVal){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetDouble(pCtx->pOut, rVal); } void sqlite3_result_error(sqlite3_context *pCtx, const char *z, int n){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); pCtx->isError = SQLITE_ERROR; pCtx->fErrorOrAux = 1; sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF8, SQLITE_TRANSIENT); } #ifndef SQLITE_OMIT_UTF16 void sqlite3_result_error16(sqlite3_context *pCtx, const void *z, int n){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); pCtx->isError = SQLITE_ERROR; pCtx->fErrorOrAux = 1; sqlite3VdbeMemSetStr(pCtx->pOut, z, n, SQLITE_UTF16NATIVE, SQLITE_TRANSIENT); } #endif void sqlite3_result_int(sqlite3_context *pCtx, int iVal){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetInt64(pCtx->pOut, (i64)iVal); } void sqlite3_result_int64(sqlite3_context *pCtx, i64 iVal){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetInt64(pCtx->pOut, iVal); } void sqlite3_result_null(sqlite3_context *pCtx){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemSetNull(pCtx->pOut); } void sqlite3_result_text( sqlite3_context *pCtx, const char *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF8, xDel); } void sqlite3_result_text64( sqlite3_context *pCtx, const char *z, sqlite3_uint64 n, void (*xDel)(void *), unsigned char enc ){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); assert( xDel!=SQLITE_DYNAMIC ); if( enc==SQLITE_UTF16 ) enc = SQLITE_UTF16NATIVE; if( n>0x7fffffff ){ (void)invokeValueDestructor(z, xDel, pCtx); }else{ setResultStrOrError(pCtx, z, (int)n, enc, xDel); } } #ifndef SQLITE_OMIT_UTF16 void sqlite3_result_text16( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF16NATIVE, xDel); } void sqlite3_result_text16be( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF16BE, xDel); } void sqlite3_result_text16le( sqlite3_context *pCtx, const void *z, int n, void (*xDel)(void *) ){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); setResultStrOrError(pCtx, z, n, SQLITE_UTF16LE, xDel); } #endif /* SQLITE_OMIT_UTF16 */ void sqlite3_result_value(sqlite3_context *pCtx, sqlite3_value *pValue){ assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) ); sqlite3VdbeMemCopy(pCtx->pOut, pValue); }
/* ** Convert pMem to type integer. Invalidate any prior representations. */ int sqlite3VdbeMemIntegerify(Mem *pMem){ assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) ); pMem->u.i = sqlite3VdbeIntValue(pMem); setTypeFlag(pMem, MEM_Int); return SQLITE_OK; }
/* ** Change the value of a Mem to be a string or a BLOB. ** ** The memory management strategy depends on the value of the xDel ** parameter. If the value passed is SQLITE_TRANSIENT, then the ** string is copied into a (possibly existing) buffer managed by the ** Mem structure. Otherwise, any existing buffer is freed and the ** pointer copied. ** ** If the string is too large (if it exceeds the SQLITE_LIMIT_LENGTH ** size limit) then no memory allocation occurs. If the string can be ** stored without allocating memory, then it is. If a memory allocation ** is required to store the string, then value of pMem is unchanged. In ** either case, SQLITE_TOOBIG is returned. */ SQLITE_PRIVATE int sqlite3VdbeMemSetStr( Mem *pMem, /* Memory cell to set to string value */ const char *z, /* String pointer */ int n, /* Bytes in string, or negative */ u8 enc, /* Encoding of z. 0 for BLOBs */ void (*xDel)(void*) /* Destructor function */ ){ int nByte = n; /* New value for pMem->n */ int iLimit; /* Maximum allowed string or blob size */ u16 flags = 0; /* New value for pMem->flags */ assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) ); assert( (pMem->flags & MEM_RowSet)==0 ); /* If z is a NULL pointer, set pMem to contain an SQL NULL. */ if( !z ){ sqlite3VdbeMemSetNull(pMem); return SQLITE_OK; } if( pMem->db ){ iLimit = pMem->db->aLimit[SQLITE_LIMIT_LENGTH]; }else{ iLimit = SQLITE_MAX_LENGTH; } flags = (enc==0?MEM_Blob:MEM_Str); if( nByte<0 ){ assert( enc!=0 ); if( enc==SQLITE_UTF8 ){ for(nByte=0; nByte<=iLimit && z[nByte]; nByte++){} }else{ for(nByte=0; nByte<=iLimit && (z[nByte] | z[nByte+1]); nByte+=2){} } flags |= MEM_Term; } /* The following block sets the new values of Mem.z and Mem.xDel. It ** also sets a flag in local variable "flags" to indicate the memory ** management (one of MEM_Dyn or MEM_Static). */ if( xDel==SQLITE_TRANSIENT ){ int nAlloc = nByte; if( flags&MEM_Term ){ nAlloc += (enc==SQLITE_UTF8?1:2); } if( nByte>iLimit ){ return SQLITE_TOOBIG; } if( sqlite3VdbeMemGrow(pMem, nAlloc, 0) ){ return SQLITE_NOMEM; } memcpy(pMem->z, z, nAlloc); }else if( xDel==SQLITE_DYNAMIC ){ sqlite3VdbeMemRelease(pMem); pMem->zMalloc = pMem->z = (char *)z; pMem->xDel = 0; }else{ sqlite3VdbeMemRelease(pMem); pMem->z = (char *)z; pMem->xDel = xDel; flags |= ((xDel==SQLITE_STATIC)?MEM_Static:MEM_Dyn); } pMem->n = nByte; pMem->flags = flags; pMem->enc = (enc==0 ? SQLITE_UTF8 : enc); pMem->type = (enc==0 ? SQLITE_BLOB : SQLITE_TEXT); #ifndef SQLITE_OMIT_UTF16 if( pMem->enc!=SQLITE_UTF8 && sqlite3VdbeMemHandleBom(pMem) ){ return SQLITE_NOMEM; } #endif if( nByte>iLimit ){ return SQLITE_TOOBIG; } return SQLITE_OK; }
/* ** Convert pMem so that it is of type MEM_Real. ** Invalidate any prior representations. */ int sqlite3VdbeMemRealify(Mem *pMem){ assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) ); pMem->r = sqlite3VdbeRealValue(pMem); setTypeFlag(pMem, MEM_Real); return SQLITE_OK; }
/* ** Enter a mutex on the given BTree object. ** 在给定的B树对象上输入一个互斥锁。 ** If the object is not sharable, then no mutex is ever required ** and this routine is a no-op. The underlying mutex is non-recursive. ** But we keep a reference count in Btree.wantToLock so the behavior ** of this interface is recursive. ** ** To avoid deadlocks, multiple Btrees are locked in the same order ** by all database connections. The p->pNext is a list of other ** Btrees belonging to the same database connection as the p Btree ** which need to be locked after p. If we cannot get a lock on ** p, then first unlock all of the others on p->pNext, then wait ** for the lock to become available on p, then relock all of the ** subsequent Btrees that desire a lock. ** 如果对象不可共享,那么不需要互斥锁并且这个程序是无操作的。这个潜在的互斥锁是非递归的。 ** 但是在Btree.wantToLock中保持对参数的计数,因此这歌接口的操作是递归的。 ** ** 为了避免死锁,多个btree以相同的顺序被所有数据库连接锁定。p->pNext是其他属于相同数据库连接的B树列表 ** 作为B树p,p->pNext需要在p后被锁。如果在p上不能的锁,那么首先在p->pNext上解除其他所有锁,然后等待 ** 直到在p上的锁可用,接着对需要加锁的所有后续B树重新加锁。 */ void sqlite3BtreeEnter(Btree *p){ Btree *pLater; /* Some basic sanity checking on the Btree. The list of Btrees ** connected by pNext and pPrev should be in sorted order by ** Btree.pBt value. All elements of the list should belong to ** the same connection. Only shared Btrees are on the list. ** 在B树上进行基本的完整性检查。通过pNext和pPrev连接的B树列表应该 ** 按Btree.pBt的值进行排序。列表的所有元素都应属于相同的连接。只有共享的B树在列表中。 */ assert( p->pNext==0 || p->pNext->pBt>p->pBt ); assert( p->pPrev==0 || p->pPrev->pBt<p->pBt ); assert( p->pNext==0 || p->pNext->db==p->db ); assert( p->pPrev==0 || p->pPrev->db==p->db ); assert( p->sharable || (p->pNext==0 && p->pPrev==0) ); /* Check for locking consistency 检查锁的一致性*/ assert( !p->locked || p->wantToLock>0 ); assert( p->sharable || p->wantToLock==0 ); /* We should already hold a lock on the database connection 在数据库连接上应该已经持有一个锁*/ assert( sqlite3_mutex_held(p->db->mutex) ); /* Unless the database is sharable and unlocked, then BtShared.db ** should already be set correctly. ** 如果数据库是可共享的并且没有被锁,那么BtShared.db应该已经被正确设置。 */ assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db ); if( !p->sharable ) return; p->wantToLock++; if( p->locked ) return; /* In most cases, we should be able to acquire the lock we ** want without having to go throught the ascending lock ** procedure that follows. Just be sure not to block. ** 在大多数情况下,我们应该能得到锁,我们想要的这个锁不必通过追溯在其后的锁进程。只是对块不确定。 */ if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){ p->pBt->db = p->db; p->locked = 1; return; } /* To avoid deadlock, first release all locks with a larger ** BtShared address. Then acquire our lock. Then reacquire ** the other BtShared locks that we used to hold in ascending ** order. ** 为了避免死锁,首先释放所有更大BtShared地址的锁。然后获得我们的锁。 ** 接着再次获取我们曾在提升顺序中持有的其他锁。 */ for(pLater=p->pNext; pLater; pLater=pLater->pNext){ assert( pLater->sharable ); assert( pLater->pNext==0 || pLater->pNext->pBt>pLater->pBt ); assert( !pLater->locked || pLater->wantToLock>0 ); if( pLater->locked ){ unlockBtreeMutex(pLater); } } lockBtreeMutex(p); for(pLater=p->pNext; pLater; pLater=pLater->pNext){ if( pLater->wantToLock ){ lockBtreeMutex(pLater); } } }
/* ** Return a block of memory of at least nBytes in size. ** Return NULL if unable. */ static void *memsys3Malloc(int nByte){ int i; int nBlock; int toFree; assert( sqlite3_mutex_held(mem.mutex) ); assert( sizeof(Mem3Block)==8 ); if( nByte<=0 ){ nBlock = 2; }else{ nBlock = (nByte + 15)/8; } assert( nBlock >= 2 ); /* STEP 1: ** Look for an entry of the correct size in either the small ** chunk table or in the large chunk hash table. This is ** successful most of the time (about 9 times out of 10). */ if( nBlock <= MX_SMALL ){ i = mem.aiSmall[nBlock-2]; if( i>0 ){ memsys3UnlinkFromList(i, &mem.aiSmall[nBlock-2]); return memsys3Checkout(i, nBlock); } }else{ int hash = nBlock % N_HASH; for(i=mem.aiHash[hash]; i>0; i=mem.aPool[i].u.list.next){ if( mem.aPool[i-1].u.hdr.size==nBlock ){ memsys3UnlinkFromList(i, &mem.aiHash[hash]); return memsys3Checkout(i, nBlock); } } } /* STEP 2: ** Try to satisfy the allocation by carving a piece off of the end ** of the master chunk. This step usually works if step 1 fails. */ if( mem.szMaster>=nBlock ){ return memsys3FromMaster(nBlock); } /* STEP 3: ** Loop through the entire memory pool. Coalesce adjacent free ** chunks. Recompute the master chunk as the largest free chunk. ** Then try again to satisfy the allocation by carving a piece off ** of the end of the master chunk. This step happens very ** rarely (we hope!) */ for(toFree=nBlock*16; toFree<SQLITE_MEMORY_SIZE*2; toFree *= 2){ memsys3OutOfMemory(toFree); if( mem.iMaster ){ memsys3Link(mem.iMaster); mem.iMaster = 0; mem.szMaster = 0; } for(i=0; i<N_HASH; i++){ memsys3Merge(&mem.aiHash[i]); } for(i=0; i<MX_SMALL-1; i++){ memsys3Merge(&mem.aiSmall[i]); } if( mem.szMaster ){ memsys3Unlink(mem.iMaster); if( mem.szMaster>=nBlock ){ return memsys3FromMaster(nBlock); } } } /* If none of the above worked, then we fail. */ return 0; }
/* ** Create a new collating function for database "db". The name is zName ** and the encoding is enc. */ static int createCollation( sqlite3* db, const char *zName, int enc, void* pCtx, int(*xCompare)(void*,int,const void*,int,const void*), void(*xDel)(void*) ){ CollSeq *pColl; int enc2; if( sqlite3SafetyCheck(db) ){ return SQLITE_MISUSE; } assert( sqlite3_mutex_held(db->mutex) ); /* If SQLITE_UTF16 is specified as the encoding type, transform this ** to one of SQLITE_UTF16LE or SQLITE_UTF16BE using the ** SQLITE_UTF16NATIVE macro. SQLITE_UTF16 is not used internally. */ enc2 = enc & ~SQLITE_UTF16_ALIGNED; if( enc2==SQLITE_UTF16 ){ enc2 = SQLITE_UTF16NATIVE; } if( (enc2&~3)!=0 ){ sqlite3Error(db, SQLITE_ERROR, "unknown encoding"); return SQLITE_ERROR; } /* Check if this call is removing or replacing an existing collation ** sequence. If so, and there are active VMs, return busy. If there ** are no active VMs, invalidate any pre-compiled statements. */ pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, strlen(zName), 0); if( pColl && pColl->xCmp ){ if( db->activeVdbeCnt ){ sqlite3Error(db, SQLITE_BUSY, "Unable to delete/modify collation sequence due to active statements"); return SQLITE_BUSY; } sqlite3ExpirePreparedStatements(db); /* If collation sequence pColl was created directly by a call to ** sqlite3_create_collation, and not generated by synthCollSeq(), ** then any copies made by synthCollSeq() need to be invalidated. ** Also, collation destructor - CollSeq.xDel() - function may need ** to be called. */ if( (pColl->enc & ~SQLITE_UTF16_ALIGNED)==enc2 ){ CollSeq *aColl = (CollSeq*)sqlite3HashFind(&db->aCollSeq, zName, strlen(zName)); int j; for(j=0; j<3; j++){ CollSeq *p = &aColl[j]; if( p->enc==pColl->enc ){ if( p->xDel ){ p->xDel(p->pUser); } p->xCmp = 0; } } } } pColl = sqlite3FindCollSeq(db, (u8)enc2, zName, strlen(zName), 1); if( pColl ){ pColl->xCmp = xCompare; pColl->pUser = pCtx; pColl->xDel = xDel; pColl->enc = enc2 | (enc & SQLITE_UTF16_ALIGNED); } sqlite3Error(db, SQLITE_OK, 0); return SQLITE_OK; }
SQLITE_API void sqlite3_result_double(sqlite3_context *pCtx, double rVal){ assert( sqlite3_mutex_held(pCtx->s.db->mutex) ); sqlite3VdbeMemSetDouble(&pCtx->s, rVal); }