1 2 #pragma ident "%Z%%M% %I% %E% SMI" 3 4 /* 5 ** 2003 September 6 6 ** 7 ** The author disclaims copyright to this source code. In place of 8 ** a legal notice, here is a blessing: 9 ** 10 ** May you do good and not evil. 11 ** May you find forgiveness for yourself and forgive others. 12 ** May you share freely, never taking more than you give. 13 ** 14 ************************************************************************* 15 ** This is the header file for information that is private to the 16 ** VDBE. This information used to all be at the top of the single 17 ** source code file "vdbe.c". When that file became too big (over 18 ** 6000 lines long) it was split up into several smaller files and 19 ** this header information was factored out. 20 */ 21 22 /* 23 ** When converting from the native format to the key format and back 24 ** again, in addition to changing the byte order we invert the high-order 25 ** bit of the most significant byte. This causes negative numbers to 26 ** sort before positive numbers in the memcmp() function. 27 */ 28 #define keyToInt(X) (sqliteVdbeByteSwap(X) ^ 0x80000000) 29 #define intToKey(X) (sqliteVdbeByteSwap((X) ^ 0x80000000)) 30 31 /* 32 ** The makefile scans this source file and creates the following 33 ** array of string constants which are the names of all VDBE opcodes. 34 ** This array is defined in a separate source code file named opcode.c 35 ** which is automatically generated by the makefile. 36 */ 37 extern char *sqliteOpcodeNames[]; 38 39 /* 40 ** SQL is translated into a sequence of instructions to be 41 ** executed by a virtual machine. Each instruction is an instance 42 ** of the following structure. 43 */ 44 typedef struct VdbeOp Op; 45 46 /* 47 ** Boolean values 48 */ 49 typedef unsigned char Bool; 50 51 /* 52 ** A cursor is a pointer into a single BTree within a database file. 53 ** The cursor can seek to a BTree entry with a particular key, or 54 ** loop over all entries of the Btree. You can also insert new BTree 55 ** entries or retrieve the key or data from the entry that the cursor 56 ** is currently pointing to. 57 ** 58 ** Every cursor that the virtual machine has open is represented by an 59 ** instance of the following structure. 60 ** 61 ** If the Cursor.isTriggerRow flag is set it means that this cursor is 62 ** really a single row that represents the NEW or OLD pseudo-table of 63 ** a row trigger. The data for the row is stored in Cursor.pData and 64 ** the rowid is in Cursor.iKey. 65 */ 66 struct Cursor { 67 BtCursor *pCursor; /* The cursor structure of the backend */ 68 int lastRecno; /* Last recno from a Next or NextIdx operation */ 69 int nextRowid; /* Next rowid returned by OP_NewRowid */ 70 Bool recnoIsValid; /* True if lastRecno is valid */ 71 Bool keyAsData; /* The OP_Column command works on key instead of data */ 72 Bool atFirst; /* True if pointing to first entry */ 73 Bool useRandomRowid; /* Generate new record numbers semi-randomly */ 74 Bool nullRow; /* True if pointing to a row with no data */ 75 Bool nextRowidValid; /* True if the nextRowid field is valid */ 76 Bool pseudoTable; /* This is a NEW or OLD pseudo-tables of a trigger */ 77 Bool deferredMoveto; /* A call to sqliteBtreeMoveto() is needed */ 78 int movetoTarget; /* Argument to the deferred sqliteBtreeMoveto() */ 79 Btree *pBt; /* Separate file holding temporary table */ 80 int nData; /* Number of bytes in pData */ 81 char *pData; /* Data for a NEW or OLD pseudo-table */ 82 int iKey; /* Key for the NEW or OLD pseudo-table row */ 83 }; 84 typedef struct Cursor Cursor; 85 86 /* 87 ** A sorter builds a list of elements to be sorted. Each element of 88 ** the list is an instance of the following structure. 89 */ 90 typedef struct Sorter Sorter; 91 struct Sorter { 92 int nKey; /* Number of bytes in the key */ 93 char *zKey; /* The key by which we will sort */ 94 int nData; /* Number of bytes in the data */ 95 char *pData; /* The data associated with this key */ 96 Sorter *pNext; /* Next in the list */ 97 }; 98 99 /* 100 ** Number of buckets used for merge-sort. 101 */ 102 #define NSORT 30 103 104 /* 105 ** Number of bytes of string storage space available to each stack 106 ** layer without having to malloc. NBFS is short for Number of Bytes 107 ** For Strings. 108 */ 109 #define NBFS 32 110 111 /* 112 ** A single level of the stack or a single memory cell 113 ** is an instance of the following structure. 114 */ 115 struct Mem { 116 int i; /* Integer value */ 117 int n; /* Number of characters in string value, including '\0' */ 118 int flags; /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */ 119 double r; /* Real value */ 120 char *z; /* String value */ 121 char zShort[NBFS]; /* Space for short strings */ 122 }; 123 typedef struct Mem Mem; 124 125 /* 126 ** Allowed values for Mem.flags 127 */ 128 #define MEM_Null 0x0001 /* Value is NULL */ 129 #define MEM_Str 0x0002 /* Value is a string */ 130 #define MEM_Int 0x0004 /* Value is an integer */ 131 #define MEM_Real 0x0008 /* Value is a real number */ 132 #define MEM_Dyn 0x0010 /* Need to call sqliteFree() on Mem.z */ 133 #define MEM_Static 0x0020 /* Mem.z points to a static string */ 134 #define MEM_Ephem 0x0040 /* Mem.z points to an ephemeral string */ 135 #define MEM_Short 0x0080 /* Mem.z points to Mem.zShort */ 136 137 /* The following MEM_ value appears only in AggElem.aMem.s.flag fields. 138 ** It indicates that the corresponding AggElem.aMem.z points to a 139 ** aggregate function context that needs to be finalized. 140 */ 141 #define MEM_AggCtx 0x0100 /* Mem.z points to an agg function context */ 142 143 /* 144 ** The "context" argument for a installable function. A pointer to an 145 ** instance of this structure is the first argument to the routines used 146 ** implement the SQL functions. 147 ** 148 ** There is a typedef for this structure in sqlite.h. So all routines, 149 ** even the public interface to SQLite, can use a pointer to this structure. 150 ** But this file is the only place where the internal details of this 151 ** structure are known. 152 ** 153 ** This structure is defined inside of vdbe.c because it uses substructures 154 ** (Mem) which are only defined there. 155 */ 156 struct sqlite_func { 157 FuncDef *pFunc; /* Pointer to function information. MUST BE FIRST */ 158 Mem s; /* The return value is stored here */ 159 void *pAgg; /* Aggregate context */ 160 u8 isError; /* Set to true for an error */ 161 u8 isStep; /* Current in the step function */ 162 int cnt; /* Number of times that the step function has been called */ 163 }; 164 165 /* 166 ** An Agg structure describes an Aggregator. Each Agg consists of 167 ** zero or more Aggregator elements (AggElem). Each AggElem contains 168 ** a key and one or more values. The values are used in processing 169 ** aggregate functions in a SELECT. The key is used to implement 170 ** the GROUP BY clause of a select. 171 */ 172 typedef struct Agg Agg; 173 typedef struct AggElem AggElem; 174 struct Agg { 175 int nMem; /* Number of values stored in each AggElem */ 176 AggElem *pCurrent; /* The AggElem currently in focus */ 177 HashElem *pSearch; /* The hash element for pCurrent */ 178 Hash hash; /* Hash table of all aggregate elements */ 179 FuncDef **apFunc; /* Information about aggregate functions */ 180 }; 181 struct AggElem { 182 char *zKey; /* The key to this AggElem */ 183 int nKey; /* Number of bytes in the key, including '\0' at end */ 184 Mem aMem[1]; /* The values for this AggElem */ 185 }; 186 187 /* 188 ** A Set structure is used for quick testing to see if a value 189 ** is part of a small set. Sets are used to implement code like 190 ** this: 191 ** x.y IN ('hi','hoo','hum') 192 */ 193 typedef struct Set Set; 194 struct Set { 195 Hash hash; /* A set is just a hash table */ 196 HashElem *prev; /* Previously accessed hash elemen */ 197 }; 198 199 /* 200 ** A Keylist is a bunch of keys into a table. The keylist can 201 ** grow without bound. The keylist stores the ROWIDs of database 202 ** records that need to be deleted or updated. 203 */ 204 typedef struct Keylist Keylist; 205 struct Keylist { 206 int nKey; /* Number of slots in aKey[] */ 207 int nUsed; /* Next unwritten slot in aKey[] */ 208 int nRead; /* Next unread slot in aKey[] */ 209 Keylist *pNext; /* Next block of keys */ 210 int aKey[1]; /* One or more keys. Extra space allocated as needed */ 211 }; 212 213 /* 214 ** A Context stores the last insert rowid, the last statement change count, 215 ** and the current statement change count (i.e. changes since last statement). 216 ** Elements of Context structure type make up the ContextStack, which is 217 ** updated by the ContextPush and ContextPop opcodes (used by triggers) 218 */ 219 typedef struct Context Context; 220 struct Context { 221 int lastRowid; /* Last insert rowid (from db->lastRowid) */ 222 int lsChange; /* Last statement change count (from db->lsChange) */ 223 int csChange; /* Current statement change count (from db->csChange) */ 224 }; 225 226 /* 227 ** An instance of the virtual machine. This structure contains the complete 228 ** state of the virtual machine. 229 ** 230 ** The "sqlite_vm" structure pointer that is returned by sqlite_compile() 231 ** is really a pointer to an instance of this structure. 232 */ 233 struct Vdbe { 234 sqlite *db; /* The whole database */ 235 Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */ 236 FILE *trace; /* Write an execution trace here, if not NULL */ 237 int nOp; /* Number of instructions in the program */ 238 int nOpAlloc; /* Number of slots allocated for aOp[] */ 239 Op *aOp; /* Space to hold the virtual machine's program */ 240 int nLabel; /* Number of labels used */ 241 int nLabelAlloc; /* Number of slots allocated in aLabel[] */ 242 int *aLabel; /* Space to hold the labels */ 243 Mem *aStack; /* The operand stack, except string values */ 244 Mem *pTos; /* Top entry in the operand stack */ 245 char **zArgv; /* Text values used by the callback */ 246 char **azColName; /* Becomes the 4th parameter to callbacks */ 247 int nCursor; /* Number of slots in aCsr[] */ 248 Cursor *aCsr; /* One element of this array for each open cursor */ 249 Sorter *pSort; /* A linked list of objects to be sorted */ 250 FILE *pFile; /* At most one open file handler */ 251 int nField; /* Number of file fields */ 252 char **azField; /* Data for each file field */ 253 int nVar; /* Number of entries in azVariable[] */ 254 char **azVar; /* Values for the OP_Variable opcode */ 255 int *anVar; /* Length of each value in azVariable[] */ 256 u8 *abVar; /* TRUE if azVariable[i] needs to be sqliteFree()ed */ 257 char *zLine; /* A single line from the input file */ 258 int nLineAlloc; /* Number of spaces allocated for zLine */ 259 int magic; /* Magic number for sanity checking */ 260 int nMem; /* Number of memory locations currently allocated */ 261 Mem *aMem; /* The memory locations */ 262 Agg agg; /* Aggregate information */ 263 int nSet; /* Number of sets allocated */ 264 Set *aSet; /* An array of sets */ 265 int nCallback; /* Number of callbacks invoked so far */ 266 Keylist *pList; /* A list of ROWIDs */ 267 int keylistStackDepth; /* The size of the "keylist" stack */ 268 Keylist **keylistStack; /* The stack used by opcodes ListPush & ListPop */ 269 int contextStackDepth; /* The size of the "context" stack */ 270 Context *contextStack; /* Stack used by opcodes ContextPush & ContextPop*/ 271 int pc; /* The program counter */ 272 int rc; /* Value to return */ 273 unsigned uniqueCnt; /* Used by OP_MakeRecord when P2!=0 */ 274 int errorAction; /* Recovery action to do in case of an error */ 275 int undoTransOnError; /* If error, either ROLLBACK or COMMIT */ 276 int inTempTrans; /* True if temp database is transactioned */ 277 int returnStack[100]; /* Return address stack for OP_Gosub & OP_Return */ 278 int returnDepth; /* Next unused element in returnStack[] */ 279 int nResColumn; /* Number of columns in one row of the result set */ 280 char **azResColumn; /* Values for one row of result */ 281 int popStack; /* Pop the stack this much on entry to VdbeExec() */ 282 char *zErrMsg; /* Error message written here */ 283 u8 explain; /* True if EXPLAIN present on SQL command */ 284 }; 285 286 /* 287 ** The following are allowed values for Vdbe.magic 288 */ 289 #define VDBE_MAGIC_INIT 0x26bceaa5 /* Building a VDBE program */ 290 #define VDBE_MAGIC_RUN 0xbdf20da3 /* VDBE is ready to execute */ 291 #define VDBE_MAGIC_HALT 0x519c2973 /* VDBE has completed execution */ 292 #define VDBE_MAGIC_DEAD 0xb606c3c8 /* The VDBE has been deallocated */ 293 294 /* 295 ** Function prototypes 296 */ 297 void sqliteVdbeCleanupCursor(Cursor*); 298 void sqliteVdbeSorterReset(Vdbe*); 299 void sqliteVdbeAggReset(Agg*); 300 void sqliteVdbeKeylistFree(Keylist*); 301 void sqliteVdbePopStack(Vdbe*,int); 302 int sqliteVdbeCursorMoveto(Cursor*); 303 int sqliteVdbeByteSwap(int); 304 #if !defined(NDEBUG) || defined(VDBE_PROFILE) 305 void sqliteVdbePrintOp(FILE*, int, Op*); 306 #endif 307