SQLite

# Object files for the SQLite library.
#
LIBOBJ = attach.o auth.o btree.o btree_rb.o build.o copy.o delete.o \
         expr.o func.o hash.o insert.o \
         main.o opcodes.o os.o pager.o parse.o pragma.o printf.o random.o \
         select.o table.o tokenize.o trigger.o update.o util.o \
         vacuum.o vdbe.o vdbeaux.o where.o tclsqlite.o

# All of the source code files.
#
SRC = \
  $(TOP)/src/attach.c \
  $(TOP)/src/auth.c \
  $(TOP)/src/btree.c \

  $(TOP)/src/tokenize.c \
  $(TOP)/src/trigger.c \
  $(TOP)/src/update.c \
  $(TOP)/src/util.c \
  $(TOP)/src/vacuum.c \
  $(TOP)/src/vdbe.c \
  $(TOP)/src/vdbe.h \
  $(TOP)/src/vdbeaux.c \
  $(TOP)/src/vdbeInt.h \
  $(TOP)/src/where.c

# Source code to the test files.
#
TESTSRC = \
  $(TOP)/src/btree.c \
  $(TOP)/src/func.c \

   sqlite.h  \
   $(TOP)/src/btree.h \
   config.h \
   $(TOP)/src/hash.h \
   opcodes.h \
   $(TOP)/src/os.h \
   $(TOP)/src/sqliteInt.h  \
   $(TOP)/src/vdbe.h \
   parse.h

# Header files used by the VDBE submodule
#
VDBEHDR = \
   $(HDR) \
   $(TOP)/src/vdbeInt.h

# This is the default Makefile target.  The objects listed here
# are what get build when you type just "make" with no arguments.
#
all:	sqlite.h config.h libsqlite.a sqlite$(EXE)

# Generate the file "last_change" which contains the date of change

# This target creates a directory named "tsrc" and fills it with
# copies of all of the C source code and header files needed to
# build on the target system.  Some of the C source code and header
# files are automatically generated.  This target takes care of
# all that automatic generation.
#
target_source:	$(SRC) $(VDBEHDR) opcodes.c
	rm -rf tsrc
	mkdir tsrc
	cp $(SRC) $(VDBEHDR) tsrc
	rm tsrc/sqlite.h.in tsrc/parse.y
	cp parse.c opcodes.c tsrc

# Rules to build the LEMON compiler generator
#
lemon:	$(TOP)/tool/lemon.c $(TOP)/tool/lempar.c
	$(BCC) -o lemon $(TOP)/tool/lemon.c

util.o:	$(TOP)/src/util.c $(HDR)
	$(TCCX) -c $(TOP)/src/util.c

vacuum.o:	$(TOP)/src/vacuum.c $(HDR)
	$(TCCX) -c $(TOP)/src/vacuum.c

vdbe.o:	$(TOP)/src/vdbe.c $(VDBEHDR)
	$(TCCX) -c $(TOP)/src/vdbe.c

vdbeaux.o:	$(TOP)/src/vdbeaux.c $(VDBEHDR)
	$(TCCX) -c $(TOP)/src/vdbeaux.c

where.o:	$(TOP)/src/where.c $(HDR)
	$(TCCX) -c $(TOP)/src/where.c

copy.o:	$(TOP)/src/copy.c $(HDR)
	$(TCCX) -c $(TOP)/src/copy.c

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** The code in this file implements execution method of the 
** Virtual Database Engine (VDBE).  A separate file ("vdbeaux.c")
** handles housekeeping details such as creating and deleting
** VDBE instances.  This file is solely interested in executing
** the VDBE program.
**
** In the external interface, an "sqlite_vm*" is an opaque pointer
** to a VDBE.
**
** The SQL parser generates a program which is then executed by
** the VDBE to do the work of the SQL statement.  VDBE programs are 
** similar in form to assembly language.  The program consists of
** a linear sequence of operations.  Each operation has an opcode 
** and 3 operands.  Operands P1 and P2 are integers.  Operand P3 
** is a null-terminated string.   The P2 operand must be non-negative.

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.239 2003/09/06 20:12:01 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"








/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test
** procedures use this information to make sure that indices are
** working correctly.  This variable has no function other than to
** help verify the correct operation of the library.
*/
int sqlite_search_count = 0;
























































































































































































































































































































































































































































































































































































































































































































/*
** Advance the virtual machine to the next output row.
**
** The return vale will be either SQLITE_BUSY, SQLITE_DONE, 
** SQLITE_ROW, SQLITE_ERROR, or SQLITE_MISUSE.
**

  }
  if( sqliteSafetyOff(db) ){
    return SQLITE_MISUSE;
  }
  return rc;
}













































/*
** Insert a new aggregate element and make it the element that
** has focus.
**
** Return 0 on success and 1 if memory is exhausted.
*/
static int AggInsert(Agg *p, char *zKey, int nKey){

    p->aStack[i].r = p->aStack[i].i;
  }else{
    p->aStack[i].r = 0.0;
  }
  p->aStack[i].flags |= STK_Real;
}




























































































































































































































































/*
** The parameters are pointers to the head of two sorted lists
** of Sorter structures.  Merge these two lists together and return
** a single sorted list.  This routine forms the core of the merge-sort
** algorithm.
**
** In the case of a tie, left sorts in front of right.

      break;
    }
  }
  zBuf[i]  = 0;
  return i>0 ? zBuf : 0;
}





















/*
** Make sure there is space in the Vdbe structure to hold at least
** mxCursor cursors.  If there is not currently enough space, then
** allocate more.
**
** If a memory allocation error occurs, return 1.  Return 0 if
** everything works.

** but that meant we more testing that we needed.  By only testing the
** flag on jump instructions, we get a (small) speed improvement.
*/
#define CHECK_FOR_INTERRUPT \
   if( db->flags & SQLITE_Interrupt ) goto abort_due_to_interrupt;









































































/*
** Execute as much of a VDBE program as we can then return.
**
** sqliteVdbeMakeReady() must be called before this routine in order to
** close the program with a final OP_Halt and to set up the callbacks
** and the error message pointer.
**

  if( p->magic!=VDBE_MAGIC_RUN ) return SQLITE_MISUSE;
  assert( db->magic==SQLITE_MAGIC_BUSY );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  if( sqlite_malloc_failed ) goto no_mem;
  if( p->popStack ){
    sqliteVdbePopStack(p, p->popStack);
    p->popStack = 0;
  }
  for(pc=p->pc; rc==SQLITE_OK; pc++){
    assert( pc>=0 && pc<p->nOp );
#ifdef VDBE_PROFILE
    origPc = pc;
    start = hwtime();
#endif
    pOp = &p->aOp[pc];

    /* Only allow tracing if NDEBUG is not defined.
    */
#ifndef NDEBUG
    if( p->trace ){
      sqliteVdbePrintOp(p->trace, pc, pOp);
    }
#endif

    switch( pOp->opcode ){

/*****************************************************************************
** What follows is a massive switch statement where each case implements a

/* Opcode: Pop P1 * *
**
** P1 elements are popped off of the top of stack and discarded.
*/
case OP_Pop: {
  assert( p->tos+1>=pOp->p1 );
  sqliteVdbePopStack(p, pOp->p1);
  break;
}

/* Opcode: Dup P1 P2 *
**
** A copy of the P1-th element of the stack 
** is made and pushed onto the top of the stack.

  }
  if( sqliteSafetyOff(db) ) goto abort_due_to_misuse; 
  if( p->xCallback(p->pCbArg, pOp->p1, &zStack[i], p->azColName)!=0 ){
    rc = SQLITE_ABORT;
  }
  if( sqliteSafetyOn(db) ) goto abort_due_to_misuse;
  p->nCallback++;
  sqliteVdbePopStack(p, pOp->p1);
  if( sqlite_malloc_failed ) goto no_mem;
  break;
}

/* Opcode: NullCallback P1 * *
**
** Invoke the callback function once with the 2nd argument (the

      break;
    }else{
      Stringify(p, i);
      nByte += aStack[i].n - 1 + nSep;
    }
  }
  if( nByte<0 ){
    if( pOp->p2==0 ) sqliteVdbePopStack(p, nField);
    p->tos++;
    aStack[p->tos].flags = STK_Null;
    zStack[p->tos] = 0;
    break;
  }
  zNew = sqliteMallocRaw( nByte );
  if( zNew==0 ) goto no_mem;
  j = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      memcpy(&zNew[j], zStack[i], aStack[i].n-1);
      j += aStack[i].n-1;
    }
    if( nSep>0 && i<p->tos ){
      memcpy(&zNew[j], zSep, nSep);
      j += nSep;
    }
  }
  zNew[j] = 0;
  if( pOp->p2==0 ) sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].flags = STK_Str|STK_Dyn;
  zStack[p->tos] = zNew;
  break;
}

    Release(p, nos);
    aStack[nos].r = b;
    aStack[nos].flags = STK_Real;
  }
  break;

divide_by_zero:
  sqliteVdbePopStack(p, 2);
  p->tos = nos;
  aStack[nos].flags = STK_Null;
  break;
}

/* Opcode: Function P1 * P3
**

  }
  ctx.pFunc = (FuncDef*)pOp->p3;
  ctx.s.flags = STK_Null;
  ctx.z = 0;
  ctx.isError = 0;
  ctx.isStep = 0;
  (*ctx.pFunc->xFunc)(&ctx, n, (const char**)&zStack[p->tos-n+1]);
  sqliteVdbePopStack(p, n);
  p->tos++;
  aStack[p->tos] = ctx.s;
  if( ctx.s.flags & STK_Dyn ){
    zStack[p->tos] = ctx.z;
  }else if( ctx.s.flags & STK_Str ){
    zStack[p->tos] = aStack[p->tos].z;
  }else{

  VERIFY( if( p->tos+1-cnt<0 ) goto not_enough_stack; )
  for(i=0; i<cnt; i++){
    if( aStack[p->tos-i].flags & STK_Null ){
      pc = pOp->p2-1;
      break;
    }
  }
  if( pOp->p1>0 ) sqliteVdbePopStack(p, cnt);
  break;
}

/* Opcode: NotNull P1 P2 *
**
** Jump to P2 if the top value on the stack is not NULL.  Pop the
** stack if P1 is greater than zero.  If P1 is less than or equal to

  }
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      memcpy(&zNewRecord[j], zStack[i], aStack[i].n);
      j += aStack[i].n;
    }
  }
  sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  if( nByte<=NBFS ){
    assert( zNewRecord==zTemp );
    memcpy(aStack[p->tos].z, zTemp, nByte);
    zStack[p->tos] = aStack[p->tos].z;
    aStack[p->tos].flags = STK_Str;

    }
  }
  if( addRowid ){
    u32 iKey;
    Integerify(p, p->tos-nField);
    iKey = intToKey(aStack[p->tos-nField].i);
    memcpy(&zNewKey[j], &iKey, sizeof(u32));
    sqliteVdbePopStack(p, nField+1);
    if( pOp->p2 && containsNull ) pc = pOp->p2 - 1;
  }else{
    if( pOp->p2==0 ) sqliteVdbePopStack(p, nField+addRowid);
  }
  p->tos++;
  aStack[p->tos].n = nByte;
  if( nByte<=NBFS ){
    assert( zNewKey==zTemp );
    zStack[p->tos] = aStack[p->tos].z;
    memcpy(zStack[p->tos], zTemp, nByte);

      sqliteSetString(&p->zErrMsg, "root page number less than 2", 0);
      rc = SQLITE_INTERNAL;
      break;
    }
  }
  VERIFY( if( i<0 ) goto bad_instruction; )
  if( expandCursorArraySize(p, i) ) goto no_mem;
  sqliteVdbeCleanupCursor(&p->aCsr[i]);
  memset(&p->aCsr[i], 0, sizeof(Cursor));
  p->aCsr[i].nullRow = 1;
  if( pX==0 ) break;
  do{
    rc = sqliteBtreeCursor(pX, p2, wrFlag, &p->aCsr[i].pCursor);
    switch( rc ){
      case SQLITE_BUSY: {

*/
case OP_OpenTemp: {
  int i = pOp->p1;
  Cursor *pCx;
  VERIFY( if( i<0 ) goto bad_instruction; )
  if( expandCursorArraySize(p, i) ) goto no_mem;
  pCx = &p->aCsr[i];
  sqliteVdbeCleanupCursor(pCx);
  memset(pCx, 0, sizeof(*pCx));
  pCx->nullRow = 1;
  rc = sqliteBtreeFactory(db, 0, 1, TEMP_PAGES, &pCx->pBt);

  if( rc==SQLITE_OK ){
    rc = sqliteBtreeBeginTrans(pCx->pBt);
  }

*/
case OP_OpenPseudo: {
  int i = pOp->p1;
  Cursor *pCx;
  VERIFY( if( i<0 ) goto bad_instruction; )
  if( expandCursorArraySize(p, i) ) goto no_mem;
  pCx = &p->aCsr[i];
  sqliteVdbeCleanupCursor(pCx);
  memset(pCx, 0, sizeof(*pCx));
  pCx->nullRow = 1;
  pCx->pseudoTable = 1;
  break;
}

/* Opcode: Close P1 * *
**
** Close a cursor previously opened as P1.  If P1 is not
** currently open, this instruction is a no-op.
*/
case OP_Close: {
  int i = pOp->p1;
  if( i>=0 && i<p->nCursor ){
    sqliteVdbeCleanupCursor(&p->aCsr[i]);
  }
  break;
}

/* Opcode: MoveTo P1 P2 *
**
** Pop the top of the stack and use its value as a key.  Reposition

/* Opcode: ListReset * * *
**
** Reset the temporary storage buffer so that it holds nothing.
*/
case OP_ListReset: {
  if( p->pList ){
    sqliteVdbeKeylistFree(p->pList);
    p->pList = 0;
  }
  break;
}

/* Opcode: ListPush * * * 
**

**
** Restore the Vdbe list to the state it was in when ListPush was last
** executed.
*/
case OP_ListPop: {
  assert(p->keylistStackDepth > 0);
  p->keylistStackDepth--;
  sqliteVdbeKeylistFree(p->pList);
  p->pList = p->keylistStack[p->keylistStackDepth];
  p->keylistStack[p->keylistStackDepth] = 0;
  if( p->keylistStackDepth == 0 ){
    sqliteFree(p->keylistStack);
    p->keylistStack = 0;
  }
  break;

      azArg[j] = 0;
    }else{
      azArg[j] = z;
      strcpy(z, zStack[i]);
      z += aStack[i].n;
    }
  }
  sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  zStack[p->tos] = (char*)azArg;
  aStack[p->tos].flags = STK_Str|STK_Dyn;
  break;
}

      memcpy(&zNewKey[j], zStack[i], aStack[i].n-1);
      j += aStack[i].n-1;
      zNewKey[j++] = 0;
    }
  }
  zNewKey[j] = 0;
  assert( j<nByte );
  sqliteVdbePopStack(p, nField);
  p->tos++;
  aStack[p->tos].n = nByte;
  aStack[p->tos].flags = STK_Str|STK_Dyn;
  zStack[p->tos] = zNewKey;
  break;
}

}

/* Opcode: SortReset * * *
**
** Remove any elements that remain on the sorter.
*/
case OP_SortReset: {
  sqliteVdbeSorterReset(p);
  break;
}

/* Opcode: FileOpen * * P3
**
** Open the file named by P3 for reading using the FileRead opcode.
** If P3 is "stdin" then open standard input for reading.

/* Opcode: AggReset * P2 *
**
** Reset the aggregator so that it no longer contains any data.
** Future aggregator elements will contain P2 values each.
*/
case OP_AggReset: {
  sqliteVdbeAggReset(&p->agg);
  p->agg.nMem = pOp->p2;
  p->agg.apFunc = sqliteMalloc( p->agg.nMem*sizeof(p->agg.apFunc[0]) );
  if( p->agg.apFunc==0 ) goto no_mem;
  break;
}

/* Opcode: AggInit * P2 P3

  ctx.pAgg = pMem->z;
  ctx.cnt = ++pMem->s.i;
  ctx.isError = 0;
  ctx.isStep = 1;
  (ctx.pFunc->xStep)(&ctx, n, (const char**)&zStack[p->tos-n]);
  pMem->z = ctx.pAgg;
  pMem->s.flags = STK_AggCtx;
  sqliteVdbePopStack(p, n+1);
  if( ctx.isError ){
    rc = SQLITE_ERROR;
  }
  break;
}

/* Opcode: AggFocus * P2 *

#ifdef VDBE_PROFILE
    {
      long long elapse = hwtime() - start;
      pOp->cycles += elapse;
      pOp->cnt++;
#if 0
        fprintf(stdout, "%10lld ", elapse);
        sqliteVdbePrintOp(stdout, origPc, &p->aOp[origPc]);
#endif
    }
#endif

    /* The following code adds nothing to the actual functionality
    ** of the program.  It is only here for testing and debugging.
    ** On the other hand, it does burn CPU cycles every time through

bad_instruction:
  sprintf(zBuf,"%d",pc);
  sqliteSetString(&p->zErrMsg, "illegal operation at ", zBuf, 0);
  rc = SQLITE_INTERNAL;
  goto vdbe_halt;
)
}

/*
** 2003 September 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the header file for information that is private to the
** VDBE.  This information used to all be at the top of the single
** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
*/

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.
** This array is defined in a separate source code file named opcode.c
** which is automatically generated by the makefile.
*/
extern char *sqliteOpcodeNames[];

/*
** SQL is translated into a sequence of instructions to be
** executed by a virtual machine.  Each instruction is an instance
** of the following structure.
*/
typedef struct VdbeOp Op;

/*
** Boolean values
*/
typedef unsigned char Bool;

/*
** A cursor is a pointer into a single BTree within a database file.
** The cursor can seek to a BTree entry with a particular key, or
** loop over all entries of the Btree.  You can also insert new BTree
** entries or retrieve the key or data from the entry that the cursor
** is currently pointing to.
** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
**
** If the Cursor.isTriggerRow flag is set it means that this cursor is
** really a single row that represents the NEW or OLD pseudo-table of
** a row trigger.  The data for the row is stored in Cursor.pData and
** the rowid is in Cursor.iKey.
*/
struct Cursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */
  int lastRecno;        /* Last recno from a Next or NextIdx operation */
  int nextRowid;        /* Next rowid returned by OP_NewRowid */
  Bool recnoIsValid;    /* True if lastRecno is valid */
  Bool keyAsData;       /* The OP_Column command works on key instead of data */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool nextRowidValid;  /* True if the nextRowid field is valid */
  Bool pseudoTable;     /* This is a NEW or OLD pseudo-tables of a trigger */
  Btree *pBt;           /* Separate file holding temporary table */
  int nData;            /* Number of bytes in pData */
  char *pData;          /* Data for a NEW or OLD pseudo-table */
  int iKey;             /* Key for the NEW or OLD pseudo-table row */
};
typedef struct Cursor Cursor;

/*
** A sorter builds a list of elements to be sorted.  Each element of
** the list is an instance of the following structure.
*/
typedef struct Sorter Sorter;
struct Sorter {
  int nKey;           /* Number of bytes in the key */
  char *zKey;         /* The key by which we will sort */
  int nData;          /* Number of bytes in the data */
  char *pData;        /* The data associated with this key */
  Sorter *pNext;      /* Next in the list */
};

/* 
** Number of buckets used for merge-sort.  
*/
#define NSORT 30

/*
** Number of bytes of string storage space available to each stack
** layer without having to malloc.  NBFS is short for Number of Bytes
** For Strings.
*/
#define NBFS 32

/*
** A single level of the stack is an instance of the following
** structure.  Except, string values are stored on a separate
** list of of pointers to character.  The reason for storing
** strings separately is so that they can be easily passed
** to the callback function.
*/
struct Stack {
  int i;         /* Integer value */
  int n;         /* Number of characters in string value, including '\0' */
  int flags;     /* Some combination of STK_Null, STK_Str, STK_Dyn, etc. */
  double r;      /* Real value */
  char z[NBFS];  /* Space for short strings */
};
typedef struct Stack Stack;

/*
** Memory cells use the same structure as the stack except that space
** for an arbitrary string is added.
*/
struct Mem {
  Stack s;       /* All values of the memory cell besides string */
  char *z;       /* String value for this memory cell */
};
typedef struct Mem Mem;

/*
** Allowed values for Stack.flags
*/
#define STK_Null      0x0001   /* Value is NULL */
#define STK_Str       0x0002   /* Value is a string */
#define STK_Int       0x0004   /* Value is an integer */
#define STK_Real      0x0008   /* Value is a real number */
#define STK_Dyn       0x0010   /* Need to call sqliteFree() on zStack[] */
#define STK_Static    0x0020   /* zStack[] points to a static string */
#define STK_Ephem     0x0040   /* zStack[] points to an ephemeral string */

/* The following STK_ value appears only in AggElem.aMem.s.flag fields.
** It indicates that the corresponding AggElem.aMem.z points to a
** aggregate function context that needs to be finalized.
*/
#define STK_AggCtx    0x0040   /* zStack[] points to an agg function context */

/*
** The "context" argument for a installable function.  A pointer to an
** instance of this structure is the first argument to the routines used
** implement the SQL functions.
**
** There is a typedef for this structure in sqlite.h.  So all routines,
** even the public interface to SQLite, can use a pointer to this structure.
** But this file is the only place where the internal details of this
** structure are known.
**
** This structure is defined inside of vdbe.c because it uses substructures
** (Stack) which are only defined there.
*/
struct sqlite_func {
  FuncDef *pFunc;   /* Pointer to function information.  MUST BE FIRST */
  Stack s;          /* Small strings, ints, and double values go here */
  char *z;          /* Space for holding dynamic string results */
  void *pAgg;       /* Aggregate context */
  u8 isError;       /* Set to true for an error */
  u8 isStep;        /* Current in the step function */
  int cnt;          /* Number of times that the step function has been called */
};

/*
** An Agg structure describes an Aggregator.  Each Agg consists of
** zero or more Aggregator elements (AggElem).  Each AggElem contains
** a key and one or more values.  The values are used in processing
** aggregate functions in a SELECT.  The key is used to implement
** the GROUP BY clause of a select.
*/
typedef struct Agg Agg;
typedef struct AggElem AggElem;
struct Agg {
  int nMem;            /* Number of values stored in each AggElem */
  AggElem *pCurrent;   /* The AggElem currently in focus */
  HashElem *pSearch;   /* The hash element for pCurrent */
  Hash hash;           /* Hash table of all aggregate elements */
  FuncDef **apFunc;    /* Information about aggregate functions */
};
struct AggElem {
  char *zKey;          /* The key to this AggElem */
  int nKey;            /* Number of bytes in the key, including '\0' at end */
  Mem aMem[1];         /* The values for this AggElem */
};

/*
** A Set structure is used for quick testing to see if a value
** is part of a small set.  Sets are used to implement code like
** this:
**            x.y IN ('hi','hoo','hum')
*/
typedef struct Set Set;
struct Set {
  Hash hash;             /* A set is just a hash table */
  HashElem *prev;        /* Previously accessed hash elemen */
};

/*
** A Keylist is a bunch of keys into a table.  The keylist can
** grow without bound.  The keylist stores the ROWIDs of database
** records that need to be deleted or updated.
*/
typedef struct Keylist Keylist;
struct Keylist {
  int nKey;         /* Number of slots in aKey[] */
  int nUsed;        /* Next unwritten slot in aKey[] */
  int nRead;        /* Next unread slot in aKey[] */
  Keylist *pNext;   /* Next block of keys */
  int aKey[1];      /* One or more keys.  Extra space allocated as needed */
};

/*
** An instance of the virtual machine.  This structure contains the complete
** state of the virtual machine.
**
** The "sqlite_vm" structure pointer that is returned by sqlite_compile()
** is really a pointer to an instance of this structure.
*/
struct Vdbe {
  sqlite *db;         /* The whole database */
  Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */
  FILE *trace;        /* Write an execution trace here, if not NULL */
  int nOp;            /* Number of instructions in the program */
  int nOpAlloc;       /* Number of slots allocated for aOp[] */
  Op *aOp;            /* Space to hold the virtual machine's program */
  int nLabel;         /* Number of labels used */
  int nLabelAlloc;    /* Number of slots allocated in aLabel[] */
  int *aLabel;        /* Space to hold the labels */
  int tos;            /* Index of top of stack */
  Stack *aStack;      /* The operand stack, except string values */
  char **zStack;      /* Text or binary values of the stack */
  char **azColName;   /* Becomes the 4th parameter to callbacks */
  int nCursor;        /* Number of slots in aCsr[] */
  Cursor *aCsr;       /* One element of this array for each open cursor */
  Sorter *pSort;      /* A linked list of objects to be sorted */
  FILE *pFile;        /* At most one open file handler */
  int nField;         /* Number of file fields */
  char **azField;     /* Data for each file field */
  int nVariable;          /* Number of entries in azVariable[] */
  char **azVariable;      /* Values for the OP_Variable opcode */
  char *zLine;            /* A single line from the input file */
  int nLineAlloc;         /* Number of spaces allocated for zLine */
  int magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
  Agg agg;                /* Aggregate information */
  int nSet;               /* Number of sets allocated */
  Set *aSet;              /* An array of sets */
  int nCallback;          /* Number of callbacks invoked so far */
  Keylist *pList;         /* A list of ROWIDs */
  int keylistStackDepth;  /* The size of the "keylist" stack */
  Keylist **keylistStack; /* The stack used by opcodes ListPush & ListPop */
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  unsigned uniqueCnt;     /* Used by OP_MakeRecord when P2!=0 */
  int errorAction;        /* Recovery action to do in case of an error */
  int undoTransOnError;   /* If error, either ROLLBACK or COMMIT */
  int inTempTrans;        /* True if temp database is transactioned */
  int returnStack[100];   /* Return address stack for OP_Gosub & OP_Return */
  int returnDepth;        /* Next unused element in returnStack[] */
  int nResColumn;         /* Number of columns in one row of the result set */
  char **azResColumn;                        /* Values for one row of result */ 
  int (*xCallback)(void*,int,char**,char**); /* Callback for SELECT results */
  void *pCbArg;                              /* First argument to xCallback() */
  int popStack;           /* Pop the stack this much on entry to VdbeExec() */
  char *zErrMsg;          /* Error message written here */
  u8 explain;             /* True if EXPLAIN present on SQL command */
};

/*
** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Here is a macro to handle the common case of popping the stack
** once.  This macro only works from within the sqliteVdbeExec()
** function.
*/
#define POPSTACK \
  assert(p->tos>=0); \
  if( aStack[p->tos].flags & STK_Dyn ) sqliteFree(zStack[p->tos]); \
  p->tos--;

/*
** Function prototypes
*/
void sqliteVdbeCleanupCursor(Cursor*);
void sqliteVdbeSorterReset(Vdbe*);
void sqliteVdbeAggReset(Agg*);
void sqliteVdbeKeylistFree(Keylist*);
void sqliteVdbePopStack(Vdbe*,int);
#if !defined(NDEBUG) || defined(VDBE_PROFILE)
void sqliteVdbePrintOp(FILE*, int, Op*);
#endif

/*
** 2003 September 6
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains code used for creating, destroying, and populating
** a VDBE (or an "sqlite_vm" as it is known to the outside world.)  Prior
** to version 2.8.7, all this code was combined into the vdbe.c source file.
** But that file was getting too big so this subroutines were split out.
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"


/*
** When debugging the code generator in a symbolic debugger, one can
** set the sqlite_vdbe_addop_trace to 1 and all opcodes will be printed
** as they are added to the instruction stream.
*/
#ifndef NDEBUG
int sqlite_vdbe_addop_trace = 0;
#endif


/*
** Create a new virtual database engine.
*/
Vdbe *sqliteVdbeCreate(sqlite *db){
  Vdbe *p;
  p = sqliteMalloc( sizeof(Vdbe) );
  if( p==0 ) return 0;
  p->db = db;
  if( db->pVdbe ){
    db->pVdbe->pPrev = p;
  }
  p->pNext = db->pVdbe;
  p->pPrev = 0;
  db->pVdbe = p;
  p->magic = VDBE_MAGIC_INIT;
  return p;
}

/*
** Turn tracing on or off
*/
void sqliteVdbeTrace(Vdbe *p, FILE *trace){
  p->trace = trace;
}

/*
** Add a new instruction to the list of instructions current in the
** VDBE.  Return the address of the new instruction.
**
** Parameters:
**
**    p               Pointer to the VDBE
**
**    op              The opcode for this instruction
**
**    p1, p2          First two of the three possible operands.
**
** Use the sqliteVdbeResolveLabel() function to fix an address and
** the sqliteVdbeChangeP3() function to change the value of the P3
** operand.
*/
int sqliteVdbeAddOp(Vdbe *p, int op, int p1, int p2){
  int i;

  i = p->nOp;
  p->nOp++;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( i>=p->nOpAlloc ){
    int oldSize = p->nOpAlloc;
    Op *aNew;
    p->nOpAlloc = p->nOpAlloc*2 + 100;
    aNew = sqliteRealloc(p->aOp, p->nOpAlloc*sizeof(Op));
    if( aNew==0 ){
      p->nOpAlloc = oldSize;
      return 0;
    }
    p->aOp = aNew;
    memset(&p->aOp[oldSize], 0, (p->nOpAlloc-oldSize)*sizeof(Op));
  }
  p->aOp[i].opcode = op;
  p->aOp[i].p1 = p1;
  if( p2<0 && (-1-p2)<p->nLabel && p->aLabel[-1-p2]>=0 ){
    p2 = p->aLabel[-1-p2];
  }
  p->aOp[i].p2 = p2;
  p->aOp[i].p3 = 0;
  p->aOp[i].p3type = P3_NOTUSED;
#ifndef NDEBUG
  if( sqlite_vdbe_addop_trace ) sqliteVdbePrintOp(0, i, &p->aOp[i]);
#endif
  return i;
}

/*
** Create a new symbolic label for an instruction that has yet to be
** coded.  The symbolic label is really just a negative number.  The
** label can be used as the P2 value of an operation.  Later, when
** the label is resolved to a specific address, the VDBE will scan
** through its operation list and change all values of P2 which match
** the label into the resolved address.
**
** The VDBE knows that a P2 value is a label because labels are
** always negative and P2 values are suppose to be non-negative.
** Hence, a negative P2 value is a label that has yet to be resolved.
*/
int sqliteVdbeMakeLabel(Vdbe *p){
  int i;
  i = p->nLabel++;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( i>=p->nLabelAlloc ){
    int *aNew;
    p->nLabelAlloc = p->nLabelAlloc*2 + 10;
    aNew = sqliteRealloc( p->aLabel, p->nLabelAlloc*sizeof(p->aLabel[0]));
    if( aNew==0 ){
      sqliteFree(p->aLabel);
    }
    p->aLabel = aNew;
  }
  if( p->aLabel==0 ){
    p->nLabel = 0;
    p->nLabelAlloc = 0;
    return 0;
  }
  p->aLabel[i] = -1;
  return -1-i;
}

/*
** Resolve label "x" to be the address of the next instruction to
** be inserted.  The parameter "x" must have been obtained from
** a prior call to sqliteVdbeMakeLabel().
*/
void sqliteVdbeResolveLabel(Vdbe *p, int x){
  int j;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( x<0 && (-x)<=p->nLabel && p->aOp ){
    if( p->aLabel[-1-x]==p->nOp ) return;
    assert( p->aLabel[-1-x]<0 );
    p->aLabel[-1-x] = p->nOp;
    for(j=0; j<p->nOp; j++){
      if( p->aOp[j].p2==x ) p->aOp[j].p2 = p->nOp;
    }
  }
}

/*
** Return the address of the next instruction to be inserted.
*/
int sqliteVdbeCurrentAddr(Vdbe *p){
  assert( p->magic==VDBE_MAGIC_INIT );
  return p->nOp;
}

/*
** Add a whole list of operations to the operation stack.  Return the
** address of the first operation added.
*/
int sqliteVdbeAddOpList(Vdbe *p, int nOp, VdbeOp const *aOp){
  int addr;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->nOp + nOp >= p->nOpAlloc ){
    int oldSize = p->nOpAlloc;
    Op *aNew;
    p->nOpAlloc = p->nOpAlloc*2 + nOp + 10;
    aNew = sqliteRealloc(p->aOp, p->nOpAlloc*sizeof(Op));
    if( aNew==0 ){
      p->nOpAlloc = oldSize;
      return 0;
    }
    p->aOp = aNew;
    memset(&p->aOp[oldSize], 0, (p->nOpAlloc-oldSize)*sizeof(Op));
  }
  addr = p->nOp;
  if( nOp>0 ){
    int i;
    for(i=0; i<nOp; i++){
      int p2 = aOp[i].p2;
      p->aOp[i+addr] = aOp[i];
      if( p2<0 ) p->aOp[i+addr].p2 = addr + ADDR(p2);
      p->aOp[i+addr].p3type = aOp[i].p3 ? P3_STATIC : P3_NOTUSED;
#ifndef NDEBUG
      if( sqlite_vdbe_addop_trace ){
        sqliteVdbePrintOp(0, i+addr, &p->aOp[i+addr]);
      }
#endif
    }
    p->nOp += nOp;
  }
  return addr;
}

/*
** Change the value of the P1 operand for a specific instruction.
** This routine is useful when a large program is loaded from a
** static array using sqliteVdbeAddOpList but we want to make a
** few minor changes to the program.
*/
void sqliteVdbeChangeP1(Vdbe *p, int addr, int val){
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p && addr>=0 && p->nOp>addr && p->aOp ){
    p->aOp[addr].p1 = val;
  }
}

/*
** Change the value of the P2 operand for a specific instruction.
** This routine is useful for setting a jump destination.
*/
void sqliteVdbeChangeP2(Vdbe *p, int addr, int val){
  assert( val>=0 );
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p && addr>=0 && p->nOp>addr && p->aOp ){
    p->aOp[addr].p2 = val;
  }
}

/*
** Change the value of the P3 operand for a specific instruction.
** This routine is useful when a large program is loaded from a
** static array using sqliteVdbeAddOpList but we want to make a
** few minor changes to the program.
**
** If n>=0 then the P3 operand is dynamic, meaning that a copy of
** the string is made into memory obtained from sqliteMalloc().
** A value of n==0 means copy bytes of zP3 up to and including the
** first null byte.  If n>0 then copy n+1 bytes of zP3.
**
** If n==P3_STATIC  it means that zP3 is a pointer to a constant static
** string and we can just copy the pointer.  n==P3_POINTER means zP3 is
** a pointer to some object other than a string.
**
** If addr<0 then change P3 on the most recently inserted instruction.
*/
void sqliteVdbeChangeP3(Vdbe *p, int addr, const char *zP3, int n){
  Op *pOp;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p==0 || p->aOp==0 ) return;
  if( addr<0 || addr>=p->nOp ){
    addr = p->nOp - 1;
    if( addr<0 ) return;
  }
  pOp = &p->aOp[addr];
  if( pOp->p3 && pOp->p3type==P3_DYNAMIC ){
    sqliteFree(pOp->p3);
    pOp->p3 = 0;
  }
  if( zP3==0 ){
    pOp->p3 = 0;
    pOp->p3type = P3_NOTUSED;
  }else if( n<0 ){
    pOp->p3 = (char*)zP3;
    pOp->p3type = n;
  }else{
    sqliteSetNString(&pOp->p3, zP3, n, 0);
    pOp->p3type = P3_DYNAMIC;
  }
}

/*
** If the P3 operand to the specified instruction appears
** to be a quoted string token, then this procedure removes 
** the quotes.
**
** The quoting operator can be either a grave ascent (ASCII 0x27)
** or a double quote character (ASCII 0x22).  Two quotes in a row
** resolve to be a single actual quote character within the string.
*/
void sqliteVdbeDequoteP3(Vdbe *p, int addr){
  Op *pOp;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->aOp==0 || addr<0 || addr>=p->nOp ) return;
  pOp = &p->aOp[addr];
  if( pOp->p3==0 || pOp->p3[0]==0 ) return;
  if( pOp->p3type==P3_POINTER ) return;
  if( pOp->p3type!=P3_DYNAMIC ){
    pOp->p3 = sqliteStrDup(pOp->p3);
    pOp->p3type = P3_DYNAMIC;
  }
  sqliteDequote(pOp->p3);
}

/*
** On the P3 argument of the given instruction, change all
** strings of whitespace characters into a single space and
** delete leading and trailing whitespace.
*/
void sqliteVdbeCompressSpace(Vdbe *p, int addr){
  unsigned char *z;
  int i, j;
  Op *pOp;
  assert( p->magic==VDBE_MAGIC_INIT );
  if( p->aOp==0 || addr<0 || addr>=p->nOp ) return;
  pOp = &p->aOp[addr];
  if( pOp->p3type==P3_POINTER ){
    return;
  }
  if( pOp->p3type!=P3_DYNAMIC ){
    pOp->p3 = sqliteStrDup(pOp->p3);
    pOp->p3type = P3_DYNAMIC;
  }
  z = (unsigned char*)pOp->p3;
  if( z==0 ) return;
  i = j = 0;
  while( isspace(z[i]) ){ i++; }
  while( z[i] ){
    if( isspace(z[i]) ){
      z[j++] = ' ';
      while( isspace(z[++i]) ){}
    }else{
      z[j++] = z[i++];
    }
  }
  while( j>0 && isspace(z[j-1]) ){ j--; }
  z[j] = 0;
}

/*
** Search for the current program for the given opcode and P2
** value.  Return the address plus 1 if found and 0 if not found.
*/
int sqliteVdbeFindOp(Vdbe *p, int op, int p2){
  int i;
  assert( p->magic==VDBE_MAGIC_INIT );
  for(i=0; i<p->nOp; i++){
    if( p->aOp[i].opcode==op && p->aOp[i].p2==p2 ) return i+1;
  }
  return 0;
}

/*
** Return the opcode for a given address.
*/
VdbeOp *sqliteVdbeGetOp(Vdbe *p, int addr){
  assert( p->magic==VDBE_MAGIC_INIT );
  assert( addr>=0 && addr<p->nOp );
  return &p->aOp[addr];
}

/*
** The following group or routines are employed by installable functions
** to return their results.
**
** The sqlite_set_result_string() routine can be used to return a string
** value or to return a NULL.  To return a NULL, pass in NULL for zResult.
** A copy is made of the string before this routine returns so it is safe
** to pass in an ephemeral string.
**
** sqlite_set_result_error() works like sqlite_set_result_string() except
** that it signals a fatal error.  The string argument, if any, is the
** error message.  If the argument is NULL a generic substitute error message
** is used.
**
** The sqlite_set_result_int() and sqlite_set_result_double() set the return
** value of the user function to an integer or a double.
**
** These routines are defined here in vdbe.c because they depend on knowing
** the internals of the sqlite_func structure which is only defined in 
** this source file.
*/
char *sqlite_set_result_string(sqlite_func *p, const char *zResult, int n){
  assert( !p->isStep );
  if( p->s.flags & STK_Dyn ){
    sqliteFree(p->z);
  }
  if( zResult==0 ){
    p->s.flags = STK_Null;
    n = 0;
    p->z = 0;
    p->s.n = 0;
  }else{
    if( n<0 ) n = strlen(zResult);
    if( n<NBFS-1 ){
      memcpy(p->s.z, zResult, n);
      p->s.z[n] = 0;
      p->s.flags = STK_Str;
      p->z = p->s.z;
    }else{
      p->z = sqliteMallocRaw( n+1 );
      if( p->z ){
        memcpy(p->z, zResult, n);
        p->z[n] = 0;
      }
      p->s.flags = STK_Str | STK_Dyn;
    }
    p->s.n = n+1;
  }
  return p->z;
}
void sqlite_set_result_int(sqlite_func *p, int iResult){
  assert( !p->isStep );
  if( p->s.flags & STK_Dyn ){
    sqliteFree(p->z);
  }
  p->s.i = iResult;
  p->s.flags = STK_Int;
}
void sqlite_set_result_double(sqlite_func *p, double rResult){
  assert( !p->isStep );
  if( p->s.flags & STK_Dyn ){
    sqliteFree(p->z);
  }
  p->s.r = rResult;
  p->s.flags = STK_Real;
}
void sqlite_set_result_error(sqlite_func *p, const char *zMsg, int n){
  assert( !p->isStep );
  sqlite_set_result_string(p, zMsg, n);
  p->isError = 1;
}

/*
** Extract the user data from a sqlite_func structure and return a
** pointer to it.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in 
** this source file.
*/
void *sqlite_user_data(sqlite_func *p){
  assert( p && p->pFunc );
  return p->pFunc->pUserData;
}

/*
** Allocate or return the aggregate context for a user function.  A new
** context is allocated on the first call.  Subsequent calls return the
** same context that was returned on prior calls.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in
** this source file.
*/
void *sqlite_aggregate_context(sqlite_func *p, int nByte){
  assert( p && p->pFunc && p->pFunc->xStep );
  if( p->pAgg==0 ){
    if( nByte<=NBFS ){
      p->pAgg = (void*)p->z;
    }else{
      p->pAgg = sqliteMalloc( nByte );
    }
  }
  return p->pAgg;
}

/*
** Return the number of times the Step function of a aggregate has been 
** called.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in
** this source file.
*/
int sqlite_aggregate_count(sqlite_func *p){
  assert( p && p->pFunc && p->pFunc->xStep );
  return p->cnt;
}

#if !defined(NDEBUG) || defined(VDBE_PROFILE)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
void sqliteVdbePrintOp(FILE *pOut, int pc, Op *pOp){
  char *zP3;
  char zPtr[40];
  if( pOp->p3type==P3_POINTER ){
    sprintf(zPtr, "ptr(%#x)", (int)pOp->p3);
    zP3 = zPtr;
  }else{
    zP3 = pOp->p3;
  }
  if( pOut==0 ) pOut = stdout;
  fprintf(pOut,"%4d %-12s %4d %4d %s\n",
      pc, sqliteOpcodeNames[pOp->opcode], pOp->p1, pOp->p2, zP3 ? zP3 : "");
  fflush(pOut);
}
#endif

/*
** Give a listing of the program in the virtual machine.
**
** The interface is the same as sqliteVdbeExec().  But instead of
** running the code, it invokes the callback once for each instruction.
** This feature is used to implement "EXPLAIN".
*/
int sqliteVdbeList(
  Vdbe *p                   /* The VDBE */
){
  sqlite *db = p->db;
  int i;
  static char *azColumnNames[] = {
     "addr", "opcode", "p1",  "p2",  "p3", 
     "int",  "text",   "int", "int", "text",
     0
  };

  assert( p->popStack==0 );
  assert( p->explain );
  p->azColName = azColumnNames;
  p->azResColumn = p->zStack;
  for(i=0; i<5; i++) p->zStack[i] = p->aStack[i].z;
  p->rc = SQLITE_OK;
  for(i=p->pc; p->rc==SQLITE_OK && i<p->nOp; i++){
    if( db->flags & SQLITE_Interrupt ){
      db->flags &= ~SQLITE_Interrupt;
      if( db->magic!=SQLITE_MAGIC_BUSY ){
        p->rc = SQLITE_MISUSE;
      }else{
        p->rc = SQLITE_INTERRUPT;
      }
      sqliteSetString(&p->zErrMsg, sqlite_error_string(p->rc), 0);
      break;
    }
    sprintf(p->zStack[0],"%d",i);
    sprintf(p->zStack[2],"%d", p->aOp[i].p1);
    sprintf(p->zStack[3],"%d", p->aOp[i].p2);
    if( p->aOp[i].p3type==P3_POINTER ){
      sprintf(p->aStack[4].z, "ptr(%#x)", (int)p->aOp[i].p3);
      p->zStack[4] = p->aStack[4].z;
    }else{
      p->zStack[4] = p->aOp[i].p3;
    }
    p->zStack[1] = sqliteOpcodeNames[p->aOp[i].opcode];
    if( p->xCallback==0 ){
      p->pc = i+1;
      p->azResColumn = p->zStack;
      p->nResColumn = 5;
      return SQLITE_ROW;
    }
    if( sqliteSafetyOff(db) ){
      p->rc = SQLITE_MISUSE;
      break;
    }
    if( p->xCallback(p->pCbArg, 5, p->zStack, p->azColName) ){
      p->rc = SQLITE_ABORT;
    }
    if( sqliteSafetyOn(db) ){
      p->rc = SQLITE_MISUSE;
    }
  }
  return p->rc==SQLITE_OK ? SQLITE_DONE : SQLITE_ERROR;
}

/*
** Prepare a virtual machine for execution.  This involves things such
** as allocating stack space and initializing the program counter.
** After the VDBE has be prepped, it can be executed by one or more
** calls to sqliteVdbeExec().  
**
** The behavior of sqliteVdbeExec() is influenced by the parameters to
** this routine.  If xCallback is NULL, then sqliteVdbeExec() will return
** with SQLITE_ROW whenever there is a row of the result set ready
** to be delivered.  p->azResColumn will point to the row and 
** p->nResColumn gives the number of columns in the row.  If xCallback
** is not NULL, then the xCallback() routine is invoked to process each
** row in the result set.
*/
void sqliteVdbeMakeReady(
  Vdbe *p,                       /* The VDBE */
  sqlite_callback xCallback,     /* Result callback */
  void *pCallbackArg,            /* 1st argument to xCallback() */
  int isExplain                  /* True if the EXPLAIN keywords is present */
){
  int n;

  assert( p!=0 );
  assert( p->aStack==0 );
  assert( p->magic==VDBE_MAGIC_INIT );

  /* Add a HALT instruction to the very end of the program.
  */
  if( p->nOp==0 || (p->aOp && p->aOp[p->nOp-1].opcode!=OP_Halt) ){
    sqliteVdbeAddOp(p, OP_Halt, 0, 0);
  }

  /* No instruction ever pushes more than a single element onto the
  ** stack.  And the stack never grows on successive executions of the
  ** same loop.  So the total number of instructions is an upper bound
  ** on the maximum stack depth required.
  **
  ** Allocation all the stack space we will ever need.
  */
  n = isExplain ? 10 : p->nOp;
  p->aStack = sqliteMalloc( n*(sizeof(p->aStack[0]) + 2*sizeof(char*)) );
  p->zStack = (char**)&p->aStack[n];
  p->azColName = (char**)&p->zStack[n];

  sqliteHashInit(&p->agg.hash, SQLITE_HASH_BINARY, 0);
  p->agg.pSearch = 0;
#ifdef MEMORY_DEBUG
  if( sqliteOsFileExists("vdbe_trace") ){
    p->trace = stdout;
  }
#endif
  p->tos = -1;
  p->pc = 0;
  p->rc = SQLITE_OK;
  p->uniqueCnt = 0;
  p->returnDepth = 0;
  p->errorAction = OE_Abort;
  p->undoTransOnError = 0;
  p->xCallback = xCallback;
  p->pCbArg = pCallbackArg;
  p->popStack =  0;
  p->explain |= isExplain;
  p->magic = VDBE_MAGIC_RUN;
#ifdef VDBE_PROFILE
  for(i=0; i<p->nOp; i++){
    p->aOp[i].cnt = 0;
    p->aOp[i].cycles = 0;
  }
#endif
}


/*
** Remove any elements that remain on the sorter for the VDBE given.
*/
void sqliteVdbeSorterReset(Vdbe *p){
  while( p->pSort ){
    Sorter *pSorter = p->pSort;
    p->pSort = pSorter->pNext;
    sqliteFree(pSorter->zKey);
    sqliteFree(pSorter->pData);
    sqliteFree(pSorter);
  }
}

/*
** Pop the stack N times.  Free any memory associated with the
** popped stack elements.
*/
void sqliteVdbePopStack(Vdbe *p, int N){
  assert( N>=0 );
  if( p->zStack==0 ) return;
  assert( p->aStack || sqlite_malloc_failed );
  if( p->aStack==0 ) return;
  while( N-- > 0 ){
    if( p->aStack[p->tos].flags & STK_Dyn ){
      sqliteFree(p->zStack[p->tos]);
    }
    p->aStack[p->tos].flags = 0;
    p->zStack[p->tos] = 0;
    p->tos--;
  }
}

/*
** Reset an Agg structure.  Delete all its contents. 
**
** For installable aggregate functions, if the step function has been
** called, make sure the finalizer function has also been called.  The
** finalizer might need to free memory that was allocated as part of its
** private context.  If the finalizer has not been called yet, call it
** now.
*/
void sqliteVdbeAggReset(Agg *pAgg){
  int i;
  HashElem *p;
  for(p = sqliteHashFirst(&pAgg->hash); p; p = sqliteHashNext(p)){
    AggElem *pElem = sqliteHashData(p);
    assert( pAgg->apFunc!=0 );
    for(i=0; i<pAgg->nMem; i++){
      Mem *pMem = &pElem->aMem[i];
      if( pAgg->apFunc[i] && (pMem->s.flags & STK_AggCtx)!=0 ){
        sqlite_func ctx;
        ctx.pFunc = pAgg->apFunc[i];
        ctx.s.flags = STK_Null;
        ctx.z = 0;
        ctx.pAgg = pMem->z;
        ctx.cnt = pMem->s.i;
        ctx.isStep = 0;
        ctx.isError = 0;
        (*pAgg->apFunc[i]->xFinalize)(&ctx);
        if( pMem->z!=0 && pMem->z!=pMem->s.z ){
          sqliteFree(pMem->z);
        }
      }else if( pMem->s.flags & STK_Dyn ){
        sqliteFree(pMem->z);
      }
    }
    sqliteFree(pElem);
  }
  sqliteHashClear(&pAgg->hash);
  sqliteFree(pAgg->apFunc);
  pAgg->apFunc = 0;
  pAgg->pCurrent = 0;
  pAgg->pSearch = 0;
  pAgg->nMem = 0;
}

/*
** Delete a keylist
*/
void sqliteVdbeKeylistFree(Keylist *p){
  while( p ){
    Keylist *pNext = p->pNext;
    sqliteFree(p);
    p = pNext;
  }
}

/*
** Close a cursor and release all the resources that cursor happens
** to hold.
*/
void sqliteVdbeCleanupCursor(Cursor *pCx){
  if( pCx->pCursor ){
    sqliteBtreeCloseCursor(pCx->pCursor);
  }
  if( pCx->pBt ){
    sqliteBtreeClose(pCx->pBt);
  }
  sqliteFree(pCx->pData);
  memset(pCx, 0, sizeof(Cursor));
}

/*
** Close all cursors
*/
static void closeAllCursors(Vdbe *p){
  int i;
  for(i=0; i<p->nCursor; i++){
    sqliteVdbeCleanupCursor(&p->aCsr[i]);
  }
  sqliteFree(p->aCsr);
  p->aCsr = 0;
  p->nCursor = 0;
}

/*
** Delete the variables in p->azVariable[]
*/
static void ClearVariableArray(Vdbe *p){
  sqliteFree(p->azVariable);
  p->nVariable = 0;
  p->azVariable = 0;
}

/*
** Clean up the VM after execution.
**
** This routine will automatically close any cursors, lists, and/or
** sorters that were left open.  It also deletes the values of
** variables in the azVariable[] array.
*/
static void Cleanup(Vdbe *p){
  int i;
  sqliteVdbePopStack(p, p->tos+1);
  closeAllCursors(p);
  if( p->aMem ){
    for(i=0; i<p->nMem; i++){
      if( p->aMem[i].s.flags & STK_Dyn ){
        sqliteFree(p->aMem[i].z);
      }
    }
  }
  sqliteFree(p->aMem);
  p->aMem = 0;
  p->nMem = 0;
  if( p->pList ){
    sqliteVdbeKeylistFree(p->pList);
    p->pList = 0;
  }
  sqliteVdbeSorterReset(p);
  if( p->pFile ){
    if( p->pFile!=stdin ) fclose(p->pFile);
    p->pFile = 0;
  }
  if( p->azField ){
    sqliteFree(p->azField);
    p->azField = 0;
  }
  p->nField = 0;
  if( p->zLine ){
    sqliteFree(p->zLine);
    p->zLine = 0;
  }
  p->nLineAlloc = 0;
  sqliteVdbeAggReset(&p->agg);
  if( p->aSet ){
    for(i=0; i<p->nSet; i++){
      sqliteHashClear(&p->aSet[i].hash);
    }
  }
  sqliteFree(p->aSet);
  p->aSet = 0;
  p->nSet = 0;
  if( p->keylistStack ){
    int ii;
    for(ii = 0; ii < p->keylistStackDepth; ii++){
      sqliteVdbeKeylistFree(p->keylistStack[ii]);
    }
    sqliteFree(p->keylistStack);
    p->keylistStackDepth = 0;
    p->keylistStack = 0;
  }
  sqliteFree(p->zErrMsg);
  p->zErrMsg = 0;
  ClearVariableArray(p);
}

/*
** Clean up a VDBE after execution but do not delete the VDBE just yet.
** Write any error messages into *pzErrMsg.  Return the result code.
**
** After this routine is run, the VDBE should be ready to be executed
** again.
*/
int sqliteVdbeReset(Vdbe *p, char **pzErrMsg){
  sqlite *db = p->db;
  int i;

  if( p->magic!=VDBE_MAGIC_RUN && p->magic!=VDBE_MAGIC_HALT ){
    sqliteSetString(pzErrMsg, sqlite_error_string(SQLITE_MISUSE), 0);
    return SQLITE_MISUSE;
  }
  if( p->zErrMsg ){
    if( pzErrMsg && *pzErrMsg==0 ){
      *pzErrMsg = p->zErrMsg;
    }else{
      sqliteFree(p->zErrMsg);
    }
    p->zErrMsg = 0;
  }
  Cleanup(p);
  if( p->rc!=SQLITE_OK ){
    switch( p->errorAction ){
      case OE_Abort: {
        if( !p->undoTransOnError ){
          for(i=0; i<db->nDb; i++){
            if( db->aDb[i].pBt ){
              sqliteBtreeRollbackCkpt(db->aDb[i].pBt);
            }
          }
          break;
        }
        /* Fall through to ROLLBACK */
      }
      case OE_Rollback: {
        sqliteRollbackAll(db);
        db->flags &= ~SQLITE_InTrans;
        db->onError = OE_Default;
        break;
      }
      default: {
        if( p->undoTransOnError ){
          sqliteRollbackAll(db);
          db->flags &= ~SQLITE_InTrans;
          db->onError = OE_Default;
        }
        break;
      }
    }
    sqliteRollbackInternalChanges(db);
  }
  for(i=0; i<db->nDb; i++){
    if( db->aDb[i].pBt && db->aDb[i].inTrans==2 ){
      sqliteBtreeCommitCkpt(db->aDb[i].pBt);
      db->aDb[i].inTrans = 1;
    }
  }
  assert( p->tos<p->pc || sqlite_malloc_failed==1 );
#ifdef VDBE_PROFILE
  {
    FILE *out = fopen("vdbe_profile.out", "a");
    if( out ){
      int i;
      fprintf(out, "---- ");
      for(i=0; i<p->nOp; i++){
        fprintf(out, "%02x", p->aOp[i].opcode);
      }
      fprintf(out, "\n");
      for(i=0; i<p->nOp; i++){
        fprintf(out, "%6d %10lld %8lld ",
           p->aOp[i].cnt,
           p->aOp[i].cycles,
           p->aOp[i].cnt>0 ? p->aOp[i].cycles/p->aOp[i].cnt : 0
        );
        sqliteVdbePrintOp(out, i, &p->aOp[i]);
      }
      fclose(out);
    }
  }
#endif
  p->magic = VDBE_MAGIC_INIT;
  return p->rc;
}

/*
** Clean up and delete a VDBE after execution.  Return an integer which is
** the result code.  Write any error message text into *pzErrMsg.
*/
int sqliteVdbeFinalize(Vdbe *p, char **pzErrMsg){
  int rc;
  sqlite *db;

  if( p->magic!=VDBE_MAGIC_RUN && p->magic!=VDBE_MAGIC_HALT ){
    sqliteSetString(pzErrMsg, sqlite_error_string(SQLITE_MISUSE), 0);
    return SQLITE_MISUSE;
  }
  db = p->db;
  rc = sqliteVdbeReset(p, pzErrMsg);
  sqliteVdbeDelete(p);
  if( db->want_to_close && db->pVdbe==0 ){
    sqlite_close(db);
  }
  return rc;
}

/*
** Set the values of all variables.  Variable $1 in the original SQL will
** be the string azValue[0].  $2 will have the value azValue[1].  And
** so forth.  If a value is out of range (for example $3 when nValue==2)
** then its value will be NULL.
**
** This routine overrides any prior call.
*/
int sqliteVdbeSetVariables(Vdbe *p, int nValue, const char **azValue){
  int i, n;
  char *z;
  if( p->magic!=VDBE_MAGIC_RUN || p->pc!=0 || p->nVariable!=0 ){
    return SQLITE_MISUSE;
  }
  ClearVariableArray(p);
  if( nValue==0 ){
    p->nVariable = 0;
    p->azVariable = 0;
  }
  for(i=n=0; i<nValue; i++){
    if( azValue[i] ) n += strlen(azValue[i]) + 1;
  }
  p->azVariable = sqliteMalloc( sizeof(p->azVariable[0])*nValue + n );
  if( p->azVariable==0 ){
    p->nVariable = 0;
    return SQLITE_NOMEM;
  }
  z = (char*)&p->azVariable[nValue];
  for(i=0; i<nValue; i++){
    if( azValue[i]==0 ){
      p->azVariable[i] = 0;
    }else{
      p->azVariable[i] = z;
      n = strlen(azValue[i]);
      memcpy(z, azValue[i], n+1);
      z += n+1;
    }
  }
  p->nVariable = nValue;
  return SQLITE_OK;
}


/*
** Delete an entire VDBE.
*/
void sqliteVdbeDelete(Vdbe *p){
  int i;
  if( p==0 ) return;
  Cleanup(p);
  if( p->pPrev ){
    p->pPrev->pNext = p->pNext;
  }else{
    assert( p->db->pVdbe==p );
    p->db->pVdbe = p->pNext;
  }
  if( p->pNext ){
    p->pNext->pPrev = p->pPrev;
  }
  p->pPrev = p->pNext = 0;
  if( p->nOpAlloc==0 ){
    p->aOp = 0;
    p->nOp = 0;
  }
  for(i=0; i<p->nOp; i++){
    if( p->aOp[i].p3type==P3_DYNAMIC ){
      sqliteFree(p->aOp[i].p3);
    }
  }
  sqliteFree(p->aOp);
  sqliteFree(p->aLabel);
  sqliteFree(p->aStack);
  p->magic = VDBE_MAGIC_DEAD;
  sqliteFree(p);
}