/*

 ** 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.

 **

 *************************************************************************

 ** Utility functions used throughout sqlite.

 **

 ** This file contains functions for allocating memory, comparing

 ** strings, and stuff like that.

 **

 ** $Id: util.c,v 1.241 2008/07/28 19:34:54 drh Exp $

 */

 #include "sqliteInt.h"

 #include <stdarg.h>

 #include <ctype.h>

 /*

 ** Return true if the floating point value is Not a Number (NaN).

 */

 int sqlite3IsNaN(double x){

   /* This NaN test sometimes fails if compiled on GCC with -ffast-math.

   ** On the other hand, the use of -ffast-math comes with the following

   ** warning:

   **

   **      This option [-ffast-math] should never be turned on by any

   **      -O option since it can result in incorrect output for programs

   **      which depend on an exact implementation of IEEE or ISO 

   **      rules/specifications for math functions.

   **

   ** Under MSVC, this NaN test may fail if compiled with a floating-

   ** point precision mode other than /fp:precise.  From the MSDN 

   ** documentation:

   **

   **      The compiler [with /fp:precise] will properly handle comparisons 

   **      involving NaN. For example, x != x evaluates to true if x is NaN 

   **      ...

   */

 #ifdef __FAST_MATH__

 # error SQLite will not work correctly with the -ffast-math option of GCC.

 #endif

   volatile double y = x;

   volatile double z = y;

   return y!=z;

 }

 /*

 ** Return the length of a string, except do not allow the string length

 ** to exceed the SQLITE_LIMIT_LENGTH setting.

 */

 int sqlite3Strlen(sqlite3 *db, const char *z){

   const char *z2 = z;

   int len;

   size_t x;

   while( *z2 ){ z2++; }

   x = z2 - z;

   len = 0x7fffffff & x;

   if( len!=x || len > db->aLimit[SQLITE_LIMIT_LENGTH] ){

     return db->aLimit[SQLITE_LIMIT_LENGTH];

   }else{

     return len;

   }

 }

 /*

 ** Set the most recent error code and error string for the sqlite

 ** handle "db". The error code is set to "err_code".

 **

 ** If it is not NULL, string zFormat specifies the format of the

 ** error string in the style of the printf functions: The following

 ** format characters are allowed:

 **

 **      %s      Insert a string

 **      %z      A string that should be freed after use

 **      %d      Insert an integer

 **      %T      Insert a token

 **      %S      Insert the first element of a SrcList

 **

 ** zFormat and any string tokens that follow it are assumed to be

 ** encoded in UTF-8.

 **

 ** To clear the most recent error for sqlite handle "db", sqlite3Error

 ** should be called with err_code set to SQLITE_OK and zFormat set

 ** to NULL.

 */

 void sqlite3Error(sqlite3 *db, int err_code, const char *zFormat, ...){

   if( db && (db->pErr || (db->pErr = sqlite3ValueNew(db))!=0) ){

     db->errCode = err_code;

     if( zFormat ){

       char *z;

       va_list ap;

       va_start(ap, zFormat);

       z = sqlite3VMPrintf(db, zFormat, ap);

       va_end(ap);

       sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);

     }else{

       sqlite3ValueSetStr(db->pErr, 0, 0, SQLITE_UTF8, SQLITE_STATIC);

     }

   }

 }

 /*

 ** Add an error message to pParse->zErrMsg and increment pParse->nErr.

 ** The following formatting characters are allowed:

 **

 **      %s      Insert a string

 **      %z      A string that should be freed after use

 **      %d      Insert an integer

 **      %T      Insert a token

 **      %S      Insert the first element of a SrcList

 **

 ** This function should be used to report any error that occurs whilst

 ** compiling an SQL statement (i.e. within sqlite3_prepare()). The

 ** last thing the sqlite3_prepare() function does is copy the error

 ** stored by this function into the database handle using sqlite3Error().

 ** Function sqlite3Error() should be used during statement execution

 ** (sqlite3_step() etc.).

 */

 void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){

   va_list ap;

   sqlite3 *db = pParse->db;

   pParse->nErr++;

   sqlite3DbFree(db, pParse->zErrMsg);

   va_start(ap, zFormat);

   pParse->zErrMsg = sqlite3VMPrintf(db, zFormat, ap);

   va_end(ap);

   if( pParse->rc==SQLITE_OK ){

     pParse->rc = SQLITE_ERROR;

   }

 }

 /*

 ** Clear the error message in pParse, if any

 */

 void sqlite3ErrorClear(Parse *pParse){

   sqlite3DbFree(pParse->db, pParse->zErrMsg);

   pParse->zErrMsg = 0;

   pParse->nErr = 0;

 }

 /*

 ** Convert an SQL-style quoted string into a normal string by removing

 ** the quote characters.  The conversion is done in-place.  If the

 ** input does not begin with a quote character, then this routine

 ** is a no-op.

 **

 ** 2002-Feb-14: This routine is extended to remove MS-Access style

 ** brackets from around identifers.  For example:  "[a-b-c]" becomes

 ** "a-b-c".

 */

 void sqlite3Dequote(char *z){

   int quote;

   int i, j;

   if( z==0 ) return;

   quote = z[0];

   switch( quote ){

     case '\'':  break;

     case '"':   break;

     case '`':   break;                /* For MySQL compatibility */

     case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */

     default:    return;

   }

   for(i=1, j=0; z[i]; i++){

     if( z[i]==quote ){

       if( z[i+1]==quote ){

         z[j++] = quote;

         i++;

       }else{

         z[j++] = 0;

         break;

       }

     }else{

       z[j++] = z[i];

     }

   }

 }

 /* Convenient short-hand */

 #define UpperToLower sqlite3UpperToLower

 /*

 ** Some systems have stricmp().  Others have strcasecmp().  Because

 ** there is no consistency, we will define our own.

 */

 int sqlite3StrICmp(const char *zLeft, const char *zRight){

   register unsigned char *a, *b;

   a = (unsigned char *)zLeft;

   b = (unsigned char *)zRight;

   while( *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }

   return UpperToLower[*a] - UpperToLower[*b];

 }

 int sqlite3StrNICmp(const char *zLeft, const char *zRight, int N){

   register unsigned char *a, *b;

   a = (unsigned char *)zLeft;

   b = (unsigned char *)zRight;

   while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }

   return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];

 }

 /*

 ** Return TRUE if z is a pure numeric string.  Return FALSE if the

 ** string contains any character which is not part of a number. If

 ** the string is numeric and contains the '.' character, set *realnum

 ** to TRUE (otherwise FALSE).

 **

 ** An empty string is considered non-numeric.

 */

 int sqlite3IsNumber(const char *z, int *realnum, u8 enc){

   int incr = (enc==SQLITE_UTF8?1:2);

   if( enc==SQLITE_UTF16BE ) z++;

   if( *z=='-' || *z=='+' ) z += incr;

   if( !isdigit(*(u8*)z) ){

     return 0;

   }

   z += incr;

   if( realnum ) *realnum = 0;

   while( isdigit(*(u8*)z) ){ z += incr; }

   if( *z=='.' ){

     z += incr;

     if( !isdigit(*(u8*)z) ) return 0;

     while( isdigit(*(u8*)z) ){ z += incr; }

     if( realnum ) *realnum = 1;

   }

   if( *z=='e' || *z=='E' ){

     z += incr;

     if( *z=='+' || *z=='-' ) z += incr;

     if( !isdigit(*(u8*)z) ) return 0;

     while( isdigit(*(u8*)z) ){ z += incr; }

     if( realnum ) *realnum = 1;

   }

   return *z==0;

 }

 /*

 ** The string z[] is an ascii representation of a real number.

 ** Convert this string to a double.

 **

 ** This routine assumes that z[] really is a valid number.  If it

 ** is not, the result is undefined.

 **

 ** This routine is used instead of the library atof() function because

 ** the library atof() might want to use "," as the decimal point instead

 ** of "." depending on how locale is set.  But that would cause problems

 ** for SQL.  So this routine always uses "." regardless of locale.

 */

 int sqlite3AtoF(const char *z, double *pResult){

 #ifndef SQLITE_OMIT_FLOATING_POINT

   int sign = 1;

   const char *zBegin = z;

   LONGDOUBLE_TYPE v1 = 0.0;

   int nSignificant = 0;

   while( isspace(*(u8*)z) ) z++;

   if( *z=='-' ){

     sign = -1;

     z++;

   }else if( *z=='+' ){

     z++;

   }

   while( z[0]=='0' ){

     z++;

   }

   while( isdigit(*(u8*)z) ){

     v1 = v1*10.0 + (*z - '0');

     z++;

     nSignificant++;

   }

   if( *z=='.' ){

     LONGDOUBLE_TYPE divisor = 1.0;

     z++;

     if( nSignificant==0 ){

       while( z[0]=='0' ){

         divisor *= 10.0;

         z++;

       }

     }

     while( isdigit(*(u8*)z) ){

       if( nSignificant<18 ){

         v1 = v1*10.0 + (*z - '0');

         divisor *= 10.0;

         nSignificant++;

       }

       z++;

     }

     v1 /= divisor;

   }

   if( *z=='e' || *z=='E' ){

     int esign = 1;

     int eval = 0;

     LONGDOUBLE_TYPE scale = 1.0;

     z++;

     if( *z=='-' ){

       esign = -1;

       z++;

     }else if( *z=='+' ){

       z++;

     }

     while( isdigit(*(u8*)z) ){

       eval = eval*10 + *z - '0';

       z++;

     }

     while( eval>=64 ){ scale *= 1.0e+64; eval -= 64; }

     while( eval>=16 ){ scale *= 1.0e+16; eval -= 16; }

     while( eval>=4 ){ scale *= 1.0e+4; eval -= 4; }

     while( eval>=1 ){ scale *= 1.0e+1; eval -= 1; }

     if( esign<0 ){

       v1 /= scale;

     }else{

       v1 *= scale;

     }

   }

   *pResult = sign<0 ? -v1 : v1;

   return z - zBegin;

 #else

   return sqlite3Atoi64(z, pResult);

 #endif /* SQLITE_OMIT_FLOATING_POINT */

 }

 /*

 ** Compare the 19-character string zNum against the text representation

 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive

 ** if zNum is less than, equal to, or greater than the string.

 **

 ** Unlike memcmp() this routine is guaranteed to return the difference

 ** in the values of the last digit if the only difference is in the

 ** last digit.  So, for example,

 **

 **      compare2pow63("9223372036854775800")

 **

 ** will return -8.

 */

 static int compare2pow63(const char *zNum){

   int c;

   c = memcmp(zNum,"922337203685477580",18);

   if( c==0 ){

     c = zNum[18] - '8';

   }

   return c;

 }

 /*

 ** Return TRUE if zNum is a 64-bit signed integer and write

 ** the value of the integer into *pNum.  If zNum is not an integer

 ** or is an integer that is too large to be expressed with 64 bits,

 ** then return false.

 **

 ** When this routine was originally written it dealt with only

 ** 32-bit numbers.  At that time, it was much faster than the

 ** atoi() library routine in RedHat 7.2.

 */

 int sqlite3Atoi64(const char *zNum, i64 *pNum){

   i64 v = 0;

   int neg;

   int i, c;

   const char *zStart;

   while( isspace(*(u8*)zNum) ) zNum++;

   if( *zNum=='-' ){

     neg = 1;

     zNum++;

   }else if( *zNum=='+' ){

     neg = 0;

     zNum++;

   }else{

     neg = 0;

   }

   zStart = zNum;

   while( zNum[0]=='0' ){ zNum++; } /* Skip over leading zeros. Ticket #2454 */

   for(i=0; (c=zNum[i])>='0' && c<='9'; i++){

     v = v*10 + c - '0';

   }

   *pNum = neg ? -v : v;

   if( c!=0 || (i==0 && zStart==zNum) || i>19 ){

     /* zNum is empty or contains non-numeric text or is longer

     ** than 19 digits (thus guaranting that it is too large) */

     return 0;

   }else if( i<19 ){

     /* Less than 19 digits, so we know that it fits in 64 bits */

     return 1;

   }else{

     /* 19-digit numbers must be no larger than 9223372036854775807 if positive

     ** or 9223372036854775808 if negative.  Note that 9223372036854665808

     ** is 2^63. */

     return compare2pow63(zNum)<neg;

   }

 }

 /*

 ** The string zNum represents an integer.  There might be some other

 ** information following the integer too, but that part is ignored.

 ** If the integer that the prefix of zNum represents will fit in a

 ** 64-bit signed integer, return TRUE.  Otherwise return FALSE.

 **

 ** This routine returns FALSE for the string -9223372036854775808 even that

 ** that number will, in theory fit in a 64-bit integer.  Positive

 ** 9223373036854775808 will not fit in 64 bits.  So it seems safer to return

 ** false.

 */

 int sqlite3FitsIn64Bits(const char *zNum, int negFlag){

   int i, c;

   int neg = 0;

   if( *zNum=='-' ){

     neg = 1;

     zNum++;

   }else if( *zNum=='+' ){

     zNum++;

   }

   if( negFlag ) neg = 1-neg;

   while( *zNum=='0' ){

     zNum++;   /* Skip leading zeros.  Ticket #2454 */

   }

   for(i=0; (c=zNum[i])>='0' && c<='9'; i++){}

   if( i<19 ){

     /* Guaranteed to fit if less than 19 digits */

     return 1;

   }else if( i>19 ){

     /* Guaranteed to be too big if greater than 19 digits */

     return 0;

   }else{

     /* Compare against 2^63. */

     return compare2pow63(zNum)<neg;

   }

 }

 /*

 ** If zNum represents an integer that will fit in 32-bits, then set

 ** *pValue to that integer and return true.  Otherwise return false.

 **

 ** Any non-numeric characters that following zNum are ignored.

 ** This is different from sqlite3Atoi64() which requires the

 ** input number to be zero-terminated.

 */

 int sqlite3GetInt32(const char *zNum, int *pValue){

   sqlite_int64 v = 0;

   int i, c;

   int neg = 0;

   if( zNum[0]=='-' ){

     neg = 1;

     zNum++;

   }else if( zNum[0]=='+' ){

     zNum++;

   }

   while( zNum[0]=='0' ) zNum++;

   for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){

     v = v*10 + c;

   }

   /* The longest decimal representation of a 32 bit integer is 10 digits:

   **

   **             1234567890

   **     2^31 -> 2147483648

   */

   if( i>10 ){

     return 0;

   }

   if( v-neg>2147483647 ){

     return 0;

   }

   if( neg ){

     v = -v;

   }

   *pValue = (int)v;

   return 1;

 }

 /*

 ** The variable-length integer encoding is as follows:

 **

 ** KEY:

 **         A = 0xxxxxxx    7 bits of data and one flag bit

 **         B = 1xxxxxxx    7 bits of data and one flag bit

 **         C = xxxxxxxx    8 bits of data

 **

 **  7 bits - A

 ** 14 bits - BA

 ** 21 bits - BBA

 ** 28 bits - BBBA

 ** 35 bits - BBBBA

 ** 42 bits - BBBBBA

 ** 49 bits - BBBBBBA

 ** 56 bits - BBBBBBBA

 ** 64 bits - BBBBBBBBC

 */

 /*

 ** Write a 64-bit variable-length integer to memory starting at p[0].

 ** The length of data write will be between 1 and 9 bytes.  The number

 ** of bytes written is returned.

 **

 ** A variable-length integer consists of the lower 7 bits of each byte

 ** for all bytes that have the 8th bit set and one byte with the 8th

 ** bit clear.  Except, if we get to the 9th byte, it stores the full

 ** 8 bits and is the last byte.

 */

 int sqlite3PutVarint(unsigned char *p, u64 v){

   int i, j, n;

   u8 buf[10];

   if( v & (((u64)0xff000000)<<32) ){

     p[8] = v;

     v >>= 8;

     for(i=7; i>=0; i--){

       p[i] = (v & 0x7f) | 0x80;

       v >>= 7;

     }

     return 9;

   }    

   n = 0;

   do{

     buf[n++] = (v & 0x7f) | 0x80;

     v >>= 7;

   }while( v!=0 );

   buf[0] &= 0x7f;

   assert( n<=9 );

   for(i=0, j=n-1; j>=0; j--, i++){

     p[i] = buf[j];

   }

   return n;

 }

 /*

 ** This routine is a faster version of sqlite3PutVarint() that only

 ** works for 32-bit positive integers and which is optimized for

 ** the common case of small integers.  A MACRO version, putVarint32,

 ** is provided which inlines the single-byte case.  All code should use

 ** the MACRO version as this function assumes the single-byte case has

 ** already been handled.

 */

 int sqlite3PutVarint32(unsigned char *p, u32 v){

 #ifndef putVarint32

   if( (v & ~0x7f)==0 ){

     p[0] = v;

     return 1;

   }

 #endif

   if( (v & ~0x3fff)==0 ){

     p[0] = (v>>7) | 0x80;

     p[1] = v & 0x7f;

     return 2;

   }

   return sqlite3PutVarint(p, v);

 }

 /*

 ** Bitmasks used by sqlite3GetVarint().  These precomputed constants

 ** are defined here rather than simply putting the constant expressions

 ** inline in order to work around bugs in the RVT compiler.

 **

 ** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f

 **

 ** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0

 */

 #define SLOT_2_0     0x001fc07f

 #define SLOT_4_2_0   0xf01fc07f

 /*

 ** Read a 64-bit variable-length integer from memory starting at p[0].

 ** Return the number of bytes read.  The value is stored in *v.

 */

 int sqlite3GetVarint(const unsigned char *p, u64 *v){

   u32 a,b,s;

   a = *p;

   /* a: p0 (unmasked) */

   if (!(a&0x80))

   {

     *v = a;

     return 1;

   }

   p++;

   b = *p;

   /* b: p1 (unmasked) */

   if (!(b&0x80))

   {

     a &= 0x7f;

     a = a<<7;

     a |= b;

     *v = a;

     return 2;

   }

   /* Verify that constants are precomputed correctly */

   assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );

   assert( SLOT_4_2_0 == ((0xf<<28) | (0x7f<<14) | (0x7f)) );

   p++;

   a = a<<14;

   a |= *p;

   /* a: p0<<14 | p2 (unmasked) */

   if (!(a&0x80))

   {

     a &= SLOT_2_0;

     b &= 0x7f;

     b = b<<7;

     a |= b;

     *v = a;

     return 3;

   }

   /* CSE1 from below */

   a &= SLOT_2_0;

   p++;

   b = b<<14;

   b |= *p;

   /* b: p1<<14 | p3 (unmasked) */

   if (!(b&0x80))

   {

     b &= SLOT_2_0;

     /* moved CSE1 up */

     /* a &= (0x7f<<14)|(0x7f); */

     a = a<<7;

     a |= b;

     *v = a;

     return 4;

   }

   /* a: p0<<14 | p2 (masked) */

   /* b: p1<<14 | p3 (unmasked) */

   /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */

   /* moved CSE1 up */

   /* a &= (0x7f<<14)|(0x7f); */

   b &= SLOT_2_0;

   s = a;

   /* s: p0<<14 | p2 (masked) */

   p++;

   a = a<<14;

   a |= *p;

   /* a: p0<<28 | p2<<14 | p4 (unmasked) */

   if (!(a&0x80))

   {

     /* we can skip these cause they were (effectively) done above in calc'ing s */

     /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */

     /* b &= (0x7f<<14)|(0x7f); */

     b = b<<7;

     a |= b;

     s = s>>18;

     *v = ((u64)s)<<32 | a;

     return 5;

   }

   /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */

   s = s<<7;

   s |= b;

   /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */

   p++;

   b = b<<14;

   b |= *p;

   /* b: p1<<28 | p3<<14 | p5 (unmasked) */

   if (!(b&0x80))

   {

     /* we can skip this cause it was (effectively) done above in calc'ing s */

     /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */

     a &= SLOT_2_0;

     a = a<<7;

     a |= b;

     s = s>>18;

     *v = ((u64)s)<<32 | a;

     return 6;

   }

   p++;

   a = a<<14;

   a |= *p;

   /* a: p2<<28 | p4<<14 | p6 (unmasked) */

   if (!(a&0x80))

   {

     a &= SLOT_4_2_0;

     b &= SLOT_2_0;

     b = b<<7;

     a |= b;

     s = s>>11;

     *v = ((u64)s)<<32 | a;

     return 7;

   }

   /* CSE2 from below */

   a &= SLOT_2_0;

   p++;

   b = b<<14;

   b |= *p;

   /* b: p3<<28 | p5<<14 | p7 (unmasked) */

   if (!(b&0x80))

   {

     b &= SLOT_4_2_0;

     /* moved CSE2 up */

     /* a &= (0x7f<<14)|(0x7f); */

     a = a<<7;

     a |= b;

     s = s>>4;

     *v = ((u64)s)<<32 | a;

     return 8;

   }

   p++;

   a = a<<15;

   a |= *p;

   /* a: p4<<29 | p6<<15 | p8 (unmasked) */

   /* moved CSE2 up */

   /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */

   b &= SLOT_2_0;

   b = b<<8;

   a |= b;

   s = s<<4;

   b = p[-4];

   b &= 0x7f;

   b = b>>3;

   s |= b;

   *v = ((u64)s)<<32 | a;

   return 9;

 }

 /*

 ** Read a 32-bit variable-length integer from memory starting at p[0].

 ** Return the number of bytes read.  The value is stored in *v.

 ** A MACRO version, getVarint32, is provided which inlines the 

 ** single-byte case.  All code should use the MACRO version as 

 ** this function assumes the single-byte case has already been handled.

 */

 int sqlite3GetVarint32(const unsigned char *p, u32 *v){

   u32 a,b;

   a = *p;

   /* a: p0 (unmasked) */

 #ifndef getVarint32

   if (!(a&0x80))

   {

     *v = a;

     return 1;

   }

 #endif

   p++;

   b = *p;

   /* b: p1 (unmasked) */

   if (!(b&0x80))

   {

     a &= 0x7f;

     a = a<<7;

     *v = a | b;

     return 2;

   }

   p++;

   a = a<<14;

   a |= *p;

   /* a: p0<<14 | p2 (unmasked) */

   if (!(a&0x80))

   {

     a &= (0x7f<<14)|(0x7f);

     b &= 0x7f;

     b = b<<7;

     *v = a | b;

     return 3;

   }

   p++;

   b = b<<14;

   b |= *p;

   /* b: p1<<14 | p3 (unmasked) */

   if (!(b&0x80))

   {

     b &= (0x7f<<14)|(0x7f);

     a &= (0x7f<<14)|(0x7f);

     a = a<<7;

     *v = a | b;

     return 4;

   }

   p++;

   a = a<<14;

   a |= *p;

   /* a: p0<<28 | p2<<14 | p4 (unmasked) */

   if (!(a&0x80))

   {

     a &= SLOT_4_2_0;

     b &= SLOT_4_2_0;

     b = b<<7;

     *v = a | b;

     return 5;

   }

   /* We can only reach this point when reading a corrupt database

   ** file.  In that case we are not in any hurry.  Use the (relatively

   ** slow) general-purpose sqlite3GetVarint() routine to extract the

   ** value. */

   {

     u64 v64;

     int n;

     p -= 4;

     n = sqlite3GetVarint(p, &v64);

     assert( n>5 && n<=9 );

     *v = (u32)v64;

     return n;

   }

 }

 /*

 ** Return the number of bytes that will be needed to store the given

 ** 64-bit integer.

 */

 int sqlite3VarintLen(u64 v){

   int i = 0;

   do{

     i++;

     v >>= 7;

   }while( v!=0 && i<9 );

   return i;

 }

 /*

 ** Read or write a four-byte big-endian integer value.

 */

 u32 sqlite3Get4byte(const u8 *p){

   return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];

 }

 void sqlite3Put4byte(unsigned char *p, u32 v){

   p[0] = v>>24;

   p[1] = v>>16;

   p[2] = v>>8;

   p[3] = v;

 }

 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)

 /*

 ** Translate a single byte of Hex into an integer.

 ** This routinen only works if h really is a valid hexadecimal

 ** character:  0..9a..fA..F

 */

 static int hexToInt(int h){

   assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );

 #ifdef SQLITE_ASCII

   h += 9*(1&(h>>6));

 #endif

 #ifdef SQLITE_EBCDIC

   h += 9*(1&~(h>>4));

 #endif

   return h & 0xf;

 }

 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */

 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)

 /*

 ** Convert a BLOB literal of the form "x'hhhhhh'" into its binary

 ** value.  Return a pointer to its binary value.  Space to hold the

 ** binary value has been obtained from malloc and must be freed by

 ** the calling routine.

 */

 void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){

   char *zBlob;

   int i;

   zBlob = (char *)sqlite3DbMallocRaw(db, n/2 + 1);

   n--;

   if( zBlob ){

     for(i=0; i<n; i+=2){

       zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);

     }

     zBlob[i/2] = 0;

   }

   return zBlob;

 }

 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */

 /*

 ** Change the sqlite.magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.

 ** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN

 ** when this routine is called.

 **

 ** This routine is called when entering an SQLite API.  The SQLITE_MAGIC_OPEN

 ** value indicates that the database connection passed into the API is

 ** open and is not being used by another thread.  By changing the value

 ** to SQLITE_MAGIC_BUSY we indicate that the connection is in use.

 ** sqlite3SafetyOff() below will change the value back to SQLITE_MAGIC_OPEN

 ** when the API exits. 

 **

 ** This routine is a attempt to detect if two threads use the

 ** same sqlite* pointer at the same time.  There is a race 

 ** condition so it is possible that the error is not detected.

 ** But usually the problem will be seen.  The result will be an

 ** error which can be used to debug the application that is

 ** using SQLite incorrectly.

 **

 ** Ticket #202:  If db->magic is not a valid open value, take care not

 ** to modify the db structure at all.  It could be that db is a stale

 ** pointer.  In other words, it could be that there has been a prior

 ** call to sqlite3_close(db) and db has been deallocated.  And we do

 ** not want to write into deallocated memory.

 */

 #ifdef SQLITE_DEBUG

 int sqlite3SafetyOn(sqlite3 *db){

   if( db->magic==SQLITE_MAGIC_OPEN ){

     db->magic = SQLITE_MAGIC_BUSY;

     assert( sqlite3_mutex_held(db->mutex) );

     return 0;

   }else if( db->magic==SQLITE_MAGIC_BUSY ){

     db->magic = SQLITE_MAGIC_ERROR;

     db->u1.isInterrupted = 1;

   }

   return 1;

 }

 #endif

 /*

 ** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.

 ** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY

 ** when this routine is called.

 */

 #ifdef SQLITE_DEBUG

 int sqlite3SafetyOff(sqlite3 *db){

   if( db->magic==SQLITE_MAGIC_BUSY ){

     db->magic = SQLITE_MAGIC_OPEN;

     assert( sqlite3_mutex_held(db->mutex) );

     return 0;

   }else{

     db->magic = SQLITE_MAGIC_ERROR;

     db->u1.isInterrupted = 1;

     return 1;

   }

 }

 #endif

 /*

 ** Check to make sure we have a valid db pointer.  This test is not

 ** foolproof but it does provide some measure of protection against

 ** misuse of the interface such as passing in db pointers that are

 ** NULL or which have been previously closed.  If this routine returns

 ** 1 it means that the db pointer is valid and 0 if it should not be

 ** dereferenced for any reason.  The calling function should invoke

 ** SQLITE_MISUSE immediately.

 **

 ** sqlite3SafetyCheckOk() requires that the db pointer be valid for

 ** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to

 ** open properly and is not fit for general use but which can be

 ** used as an argument to sqlite3_errmsg() or sqlite3_close().

 */

 int sqlite3SafetyCheckOk(sqlite3 *db){

   int magic;

   if( db==0 ) return 0;

   magic = db->magic;

   if( magic!=SQLITE_MAGIC_OPEN &&

       magic!=SQLITE_MAGIC_BUSY ) return 0;

   return 1;

 }

 int sqlite3SafetyCheckSickOrOk(sqlite3 *db){

   int magic;

   if( db==0 ) return 0;

   magic = db->magic;

   if( magic!=SQLITE_MAGIC_SICK &&

       magic!=SQLITE_MAGIC_OPEN &&

       magic!=SQLITE_MAGIC_BUSY ) return 0;

   return 1;

 }