sqlite3/vdbeInt.h

   1 /*
   2 ** 2003 September 6
   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 ** This is the header file for information that is private to the
  13 ** VDBE.  This information used to all be at the top of the single
  14 ** source code file "vdbe.c".  When that file became too big (over
  15 ** 6000 lines long) it was split up into several smaller files and
  16 ** this header information was factored out.
  17 */
  18
  19 /*
  20 ** intToKey() and keyToInt() used to transform the rowid.  But with
  21 ** the latest versions of the design they are no-ops.
  22 */
  23 #define keyToInt(X)   (X)
  24 #define intToKey(X)   (X)
  25
  26 /*
  27 ** The makefile scans the vdbe.c source file and creates the following
  28 ** array of string constants which are the names of all VDBE opcodes.  This
  29 ** array is defined in a separate source code file named opcode.c which is
  30 ** automatically generated by the makefile.
  31 */
  32 extern char *sqlite3OpcodeNames[];
  33
  34 /*
  35 ** SQL is translated into a sequence of instructions to be
  36 ** executed by a virtual machine.  Each instruction is an instance
  37 ** of the following structure.
  38 */
  39 typedef struct VdbeOp Op;
  40
  41 /*
  42 ** Boolean values
  43 */
  44 typedef unsigned char Bool;
  45
  46 /*
  47 ** A cursor is a pointer into a single BTree within a database file.
  48 ** The cursor can seek to a BTree entry with a particular key, or
  49 ** loop over all entries of the Btree.  You can also insert new BTree
  50 ** entries or retrieve the key or data from the entry that the cursor
  51 ** is currently pointing to.
  52 **
  53 ** Every cursor that the virtual machine has open is represented by an
  54 ** instance of the following structure.
  55 **
  56 ** If the Cursor.isTriggerRow flag is set it means that this cursor is
  57 ** really a single row that represents the NEW or OLD pseudo-table of
  58 ** a row trigger.  The data for the row is stored in Cursor.pData and
  59 ** the rowid is in Cursor.iKey.
  60 */
  61 struct Cursor {
  62   BtCursor *pCursor;    /* The cursor structure of the backend */
  63   i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */
  64   i64 nextRowid;        /* Next rowid returned by OP_NewRowid */
  65   Bool zeroed;          /* True if zeroed out and ready for reuse */
  66   Bool rowidIsValid;    /* True if lastRowid is valid */
  67   Bool atFirst;         /* True if pointing to first entry */
  68   Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  69   Bool nullRow;         /* True if pointing to a row with no data */
  70   Bool nextRowidValid;  /* True if the nextRowid field is valid */
  71   Bool pseudoTable;     /* This is a NEW or OLD pseudo-tables of a trigger */
  72   Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
  73   Bool isTable;         /* True if a table requiring integer keys */
  74   Bool isIndex;         /* True if an index containing keys only - no data */
  75   u8 bogusIncrKey;      /* Something for pIncrKey to point to if pKeyInfo==0 */
  76   i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
  77   Btree *pBt;           /* Separate file holding temporary table */
  78   int nData;            /* Number of bytes in pData */
  79   char *pData;          /* Data for a NEW or OLD pseudo-table */
  80   i64 iKey;             /* Key for the NEW or OLD pseudo-table row */
  81   u8 *pIncrKey;         /* Pointer to pKeyInfo->incrKey */
  82   KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
  83   int nField;           /* Number of fields in the header */
  84
  85   /* Cached information about the header for the data record that the
  86   ** cursor is currently pointing to.  Only valid if cacheValid is true.
  87   ** zRow might point to (ephemeral) data for the current row, or it might
  88   ** be NULL. */
  89   Bool cacheValid;      /* True if the cache is valid */
  90   int payloadSize;      /* Total number of bytes in the record */
  91   u32 *aType;           /* Type values for all entries in the record */
  92   u32 *aOffset;         /* Cached offsets to the start of each columns data */
  93   u8 *aRow;             /* Data for the current row, if all on one page */
  94 };
  95 typedef struct Cursor Cursor;
  96
  97 /*
  98 ** Number of bytes of string storage space available to each stack
  99 ** layer without having to malloc.  NBFS is short for Number of Bytes
 100 ** For Strings.
 101 */
 102 #define NBFS 32
 103
 104 /*
 105 ** Internally, the vdbe manipulates nearly all SQL values as Mem
 106 ** structures. Each Mem struct may cache multiple representations (string,
 107 ** integer etc.) of the same value.  A value (and therefore Mem structure)
 108 ** has the following properties:
 109 **
 110 ** Each value has a manifest type. The manifest type of the value stored
 111 ** in a Mem struct is returned by the MemType(Mem*) macro. The type is
 112 ** one of SQLITE_NULL, SQLITE_INTEGER, SQLITE_REAL, SQLITE_TEXT or
 113 ** SQLITE_BLOB.
 114 */
 115 struct Mem {
 116   i64 i;              /* Integer value */
 117   int n;              /* Number of characters in string value, including '\0' */
 118   u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
 119   u8  type;           /* One of MEM_Null, MEM_Str, etc. */
 120   u8  enc;            /* TEXT_Utf8, TEXT_Utf16le, or TEXT_Utf16be */
 121   double r;           /* Real value */
 122   char *z;            /* String or BLOB value */
 123   void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
 124   char zShort[NBFS];  /* Space for short strings */
 125 };
 126 typedef struct Mem Mem;
 127
 128 /*
 129 ** A sorter builds a list of elements to be sorted.  Each element of
 130 ** the list is an instance of the following structure.
 131 */
 132 typedef struct Sorter Sorter;
 133 struct Sorter {
 134   int nKey;           /* Number of bytes in the key */
 135   char *zKey;         /* The key by which we will sort */
 136   Mem data;
 137   Sorter *pNext;      /* Next in the list */
 138 };
 139
 140 /*
 141 ** Number of buckets used for merge-sort.
 142 */
 143 #define NSORT 30
 144
 145 /* One or more of the following flags are set to indicate the validOK
 146 ** representations of the value stored in the Mem struct.
 147 **
 148 ** If the MEM_Null flag is set, then the value is an SQL NULL value.
 149 ** No other flags may be set in this case.
 150 **
 151 ** If the MEM_Str flag is set then Mem.z points at a string representation.
 152 ** Usually this is encoded in the same unicode encoding as the main
 153 ** database (see below for exceptions). If the MEM_Term flag is also
 154 ** set, then the string is nul terminated. The MEM_Int and MEM_Real
 155 ** flags may coexist with the MEM_Str flag.
 156 **
 157 ** Multiple of these values can appear in Mem.flags.  But only one
 158 ** at a time can appear in Mem.type.
 159 */
 160 #define MEM_Null      0x0001   /* Value is NULL */
 161 #define MEM_Str       0x0002   /* Value is a string */
 162 #define MEM_Int       0x0004   /* Value is an integer */
 163 #define MEM_Real      0x0008   /* Value is a real number */
 164 #define MEM_Blob      0x0010   /* Value is a BLOB */
 165
 166 /* Whenever Mem contains a valid string or blob representation, one of
 167 ** the following flags must be set to determine the memory management
 168 ** policy for Mem.z.  The MEM_Term flag tells us whether or not the
 169 ** string is \000 or \u0000 terminated
 170 */
 171 #define MEM_Term      0x0020   /* String rep is nul terminated */
 172 #define MEM_Dyn       0x0040   /* Need to call sqliteFree() on Mem.z */
 173 #define MEM_Static    0x0080   /* Mem.z points to a static string */
 174 #define MEM_Ephem     0x0100   /* Mem.z points to an ephemeral string */
 175 #define MEM_Short     0x0200   /* Mem.z points to Mem.zShort */
 176
 177 /* The following MEM_ value appears only in AggElem.aMem.s.flag fields.
 178 ** It indicates that the corresponding AggElem.aMem.z points to a
 179 ** aggregate function context that needs to be finalized.
 180 */
 181 #define MEM_AggCtx    0x0400  /* Mem.z points to an agg function context */
 182
 183
 184 /* A VdbeFunc is just a FuncDef (defined in sqliteInt.h) that contains
 185 ** additional information about auxiliary information bound to arguments
 186 ** of the function.  This is used to implement the sqlite3_get_auxdata()
 187 ** and sqlite3_set_auxdata() APIs.  The "auxdata" is some auxiliary data
 188 ** that can be associated with a constant argument to a function.  This
 189 ** allows functions such as "regexp" to compile their constant regular
 190 ** expression argument once and reused the compiled code for multiple
 191 ** invocations.
 192 */
 193 struct VdbeFunc {
 194   FuncDef *pFunc;               /* The definition of the function */
 195   int nAux;                     /* Number of entries allocated for apAux[] */
 196   struct AuxData {
 197     void *pAux;                   /* Aux data for the i-th argument */
 198     void (*xDelete)(void *);      /* Destructor for the aux data */
 199   } apAux[1];                   /* One slot for each function argument */
 200 };
 201 typedef struct VdbeFunc VdbeFunc;
 202
 203 /*
 204 ** The "context" argument for a installable function.  A pointer to an
 205 ** instance of this structure is the first argument to the routines used
 206 ** implement the SQL functions.
 207 **
 208 ** There is a typedef for this structure in sqlite.h.  So all routines,
 209 ** even the public interface to SQLite, can use a pointer to this structure.
 210 ** But this file is the only place where the internal details of this
 211 ** structure are known.
 212 **
 213 ** This structure is defined inside of vdbe.c because it uses substructures
 214 ** (Mem) which are only defined there.
 215 */
 216 struct sqlite3_context {
 217   FuncDef *pFunc;   /* Pointer to function information.  MUST BE FIRST */
 218   VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
 219   Mem s;            /* The return value is stored here */
 220   void *pAgg;       /* Aggregate context */
 221   u8 isError;       /* Set to true for an error */
 222   int cnt;          /* Number of times that the step function has been called */
 223   CollSeq *pColl;
 224 };
 225
 226 /*
 227 ** An Agg structure describes an Aggregator.  Each Agg consists of
 228 ** zero or more Aggregator elements (AggElem).  Each AggElem contains
 229 ** a key and one or more values.  The values are used in processing
 230 ** aggregate functions in a SELECT.  The key is used to implement
 231 ** the GROUP BY clause of a select.
 232 */
 233 typedef struct Agg Agg;
 234 typedef struct AggElem AggElem;
 235 struct Agg {
 236   int nMem;            /* Number of values stored in each AggElem */
 237   AggElem *pCurrent;   /* The AggElem currently in focus */
 238   FuncDef **apFunc;    /* Information about aggregate functions */
 239   Btree *pBtree;       /* The tmp. btree used to group elements, if required. */
 240   BtCursor *pCsr;      /* Read/write cursor to the table in pBtree */
 241   int nTab;            /* Root page of the table in pBtree */
 242   u8 searching;        /* True between the first AggNext and AggReset */
 243 };
 244 struct AggElem {
 245   char *zKey;          /* The key to this AggElem */
 246   int nKey;            /* Number of bytes in the key, including '\0' at end */
 247   Mem aMem[1];         /* The values for this AggElem */
 248 };
 249
 250 /*
 251 ** A Set structure is used for quick testing to see if a value
 252 ** is part of a small set.  Sets are used to implement code like
 253 ** this:
 254 **            x.y IN ('hi','hoo','hum')
 255 */
 256 typedef struct Set Set;
 257 struct Set {
 258   Hash hash;             /* A set is just a hash table */
 259   HashElem *prev;        /* Previously accessed hash elemen */
 260 };
 261
 262 /*
 263 ** A Keylist is a bunch of keys into a table.  The keylist can
 264 ** grow without bound.  The keylist stores the ROWIDs of database
 265 ** records that need to be deleted or updated.
 266 */
 267 typedef struct Keylist Keylist;
 268 struct Keylist {
 269   int nKey;         /* Number of slots in aKey[] */
 270   int nUsed;        /* Next unwritten slot in aKey[] */
 271   int nRead;        /* Next unread slot in aKey[] */
 272   Keylist *pNext;   /* Next block of keys */
 273   i64 aKey[1];      /* One or more keys.  Extra space allocated as needed */
 274 };
 275
 276 /*
 277 ** A Context stores the last insert rowid, the last statement change count,
 278 ** and the current statement change count (i.e. changes since last statement).
 279 ** The current keylist is also stored in the context.
 280 ** Elements of Context structure type make up the ContextStack, which is
 281 ** updated by the ContextPush and ContextPop opcodes (used by triggers).
 282 ** The context is pushed before executing a trigger a popped when the
 283 ** trigger finishes.
 284 */
 285 typedef struct Context Context;
 286 struct Context {
 287   int lastRowid;    /* Last insert rowid (sqlite3.lastRowid) */
 288   int nChange;      /* Statement changes (Vdbe.nChanges)     */
 289   Keylist *pList;   /* Records that will participate in a DELETE or UPDATE */
 290 };
 291
 292 /*
 293 ** An instance of the virtual machine.  This structure contains the complete
 294 ** state of the virtual machine.
 295 **
 296 ** The "sqlite3_stmt" structure pointer that is returned by sqlite3_compile()
 297 ** is really a pointer to an instance of this structure.
 298 */
 299 struct Vdbe {
 300   sqlite3 *db;        /* The whole database */
 301   Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */
 302   FILE *trace;        /* Write an execution trace here, if not NULL */
 303   int nOp;            /* Number of instructions in the program */
 304   int nOpAlloc;       /* Number of slots allocated for aOp[] */
 305   Op *aOp;            /* Space to hold the virtual machine's program */
 306   int nLabel;         /* Number of labels used */
 307   int nLabelAlloc;    /* Number of slots allocated in aLabel[] */
 308   int *aLabel;        /* Space to hold the labels */
 309   Mem *aStack;        /* The operand stack, except string values */
 310   Mem *pTos;          /* Top entry in the operand stack */
 311   Mem **apArg;        /* Arguments to currently executing user function */
 312   Mem *aColName;      /* Column names to return */
 313   int nCursor;        /* Number of slots in apCsr[] */
 314   Cursor **apCsr;     /* One element of this array for each open cursor */
 315   Sorter *pSort;      /* A linked list of objects to be sorted */
 316   Sorter *pSortTail;  /* Last element on the pSort list */
 317   int nVar;           /* Number of entries in aVar[] */
 318   Mem *aVar;          /* Values for the OP_Variable opcode. */
 319   char **azVar;       /* Name of variables */
 320   int okVar;          /* True if azVar[] has been initialized */
 321   int magic;              /* Magic number for sanity checking */
 322   int nMem;               /* Number of memory locations currently allocated */
 323   Mem *aMem;              /* The memory locations */
 324   int nAgg;               /* Number of elements in apAgg */
 325   Agg *apAgg;             /* Array of aggregate contexts */
 326   Agg *pAgg;              /* Current aggregate context */
 327   int nCallback;          /* Number of callbacks invoked so far */
 328   Keylist *pList;         /* A list of ROWIDs */
 329   int contextStackTop;    /* Index of top element in the context stack */
 330   int contextStackDepth;  /* The size of the "context" stack */
 331   Context *contextStack;  /* Stack used by opcodes ContextPush & ContextPop*/
 332   int pc;                 /* The program counter */
 333   int rc;                 /* Value to return */
 334   unsigned uniqueCnt;     /* Used by OP_MakeRecord when P2!=0 */
 335   int errorAction;        /* Recovery action to do in case of an error */
 336   int inTempTrans;        /* True if temp database is transactioned */
 337   int returnStack[100];   /* Return address stack for OP_Gosub & OP_Return */
 338   int returnDepth;        /* Next unused element in returnStack[] */
 339   int nResColumn;         /* Number of columns in one row of the result set */
 340   char **azResColumn;     /* Values for one row of result */
 341   int popStack;           /* Pop the stack this much on entry to VdbeExec() */
 342   STRPTR zErrMsg;          /* Error message written here */
 343   u8 resOnStack;          /* True if there are result values on the stack */
 344   u8 explain;             /* True if EXPLAIN present on SQL command */
 345   u8 changeCntOn;         /* True to update the change-counter */
 346   u8 aborted;             /* True if ROLLBACK in another VM causes an abort */
 347   u8 expired;             /* True if the VM needs to be recompiled */
 348   int nChange;            /* Number of db changes made since last reset */
 349 };
 350
 351 /*
 352 ** The following are allowed values for Vdbe.magic
 353 */
 354 #define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
 355 #define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
 356 #define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
 357 #define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */
 358
 359 /*
 360 ** Function prototypes
 361 */
 362 void sqlite3VdbeFreeCursor(Cursor*);
 363 void sqlite3VdbeSorterReset(Vdbe*);
 364 int sqlite3VdbeAggReset(sqlite3*, Agg *, KeyInfo *);
 365 void sqlite3VdbeKeylistFree(Keylist*);
 366 void sqliteVdbePopStack(Vdbe*,int);
 367 int sqlite3VdbeCursorMoveto(Cursor*);
 368 #if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
 369 void sqlite3VdbePrintOp(FILE*, int, Op*);
 370 #endif
 371 #ifdef SQLITE_DEBUG
 372 void sqlite3VdbePrintSql(Vdbe*);
 373 #endif
 374 int sqlite3VdbeSerialTypeLen(u32);
 375 u32 sqlite3VdbeSerialType(Mem*);
 376 int sqlite3VdbeSerialPut(unsigned char*, Mem*);
 377 int sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
 378 void sqlite3VdbeDeleteAuxData(VdbeFunc*, int);
 379
 380 int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
 381 int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);
 382 int sqlite3VdbeIdxRowid(BtCursor *, i64 *);
 383 int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
 384 int sqlite3VdbeRecordCompare(void*,int,const void*,int, const void*);
 385 int sqlite3VdbeIdxRowidLen(int,const u8*);
 386 int sqlite3VdbeExec(Vdbe*);
 387 int sqlite3VdbeList(Vdbe*);
 388 int sqlite3VdbeHalt(Vdbe*);
 389 int sqlite3VdbeChangeEncoding(Mem *, int);
 390 int sqlite3VdbeMemCopy(Mem*, const Mem*);
 391 void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);
 392 int sqlite3VdbeMemMove(Mem*, Mem*);
 393 int sqlite3VdbeMemNulTerminate(Mem*);
 394 int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, void(*)(void*));
 395 void sqlite3VdbeMemSetInt64(Mem*, i64);
 396 void sqlite3VdbeMemSetDouble(Mem*, double);
 397 void sqlite3VdbeMemSetNull(Mem*);
 398 int sqlite3VdbeMemMakeWriteable(Mem*);
 399 int sqlite3VdbeMemDynamicify(Mem*);
 400 int sqlite3VdbeMemStringify(Mem*, int);
 401 i64 sqlite3VdbeIntValue(Mem*);
 402 int sqlite3VdbeMemIntegerify(Mem*);
 403 double sqlite3VdbeRealValue(Mem*);
 404 int sqlite3VdbeMemRealify(Mem*);
 405 int sqlite3VdbeMemFromBtree(BtCursor*,int,int,int,Mem*);
 406 void sqlite3VdbeMemRelease(Mem *p);
 407 #ifndef NDEBUG
 408 void sqlite3VdbeMemSanity(Mem*, u8);
 409 int sqlite3VdbeOpcodeNoPush(u8);
 410 #endif
 411 int sqlite3VdbeMemTranslate(Mem*, u8);
 412 void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf, int nBuf);
 413 int sqlite3VdbeMemHandleBom(Mem *pMem);