extensions/sqlite/sqlite-source/util.c
author Asher Baker <asherkin@gmail.com>
Thu Apr 26 16:58:18 2012 +0100 (2012-04-26)
changeset 3488 bee90c8ef6c3
parent 1952 b7aa2b626807
permissions -rw-r--r--
Fixed client serials not being unique on Windows (bug 5285, r=psychonic).
     1 /*
     2 ** 2001 September 15
     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 ** Utility functions used throughout sqlite.
    13 **
    14 ** This file contains functions for allocating memory, comparing
    15 ** strings, and stuff like that.
    16 **
    17 ** $Id$
    18 */
    19 #include "sqliteInt.h"
    20 #include <stdarg.h>
    21 #include <ctype.h>
    22 
    23 
    24 /*
    25 ** Set the most recent error code and error string for the sqlite
    26 ** handle "db". The error code is set to "err_code".
    27 **
    28 ** If it is not NULL, string zFormat specifies the format of the
    29 ** error string in the style of the printf functions: The following
    30 ** format characters are allowed:
    31 **
    32 **      %s      Insert a string
    33 **      %z      A string that should be freed after use
    34 **      %d      Insert an integer
    35 **      %T      Insert a token
    36 **      %S      Insert the first element of a SrcList
    37 **
    38 ** zFormat and any string tokens that follow it are assumed to be
    39 ** encoded in UTF-8.
    40 **
    41 ** To clear the most recent error for sqlite handle "db", sqlite3Error
    42 ** should be called with err_code set to SQLITE_OK and zFormat set
    43 ** to NULL.
    44 */
    45 void sqlite3Error(sqlite3 *db, int err_code, const char *zFormat, ...){
    46   if( db && (db->pErr || (db->pErr = sqlite3ValueNew(db))!=0) ){
    47     db->errCode = err_code;
    48     if( zFormat ){
    49       char *z;
    50       va_list ap;
    51       va_start(ap, zFormat);
    52       z = sqlite3VMPrintf(db, zFormat, ap);
    53       va_end(ap);
    54       sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, sqlite3_free);
    55     }else{
    56       sqlite3ValueSetStr(db->pErr, 0, 0, SQLITE_UTF8, SQLITE_STATIC);
    57     }
    58   }
    59 }
    60 
    61 /*
    62 ** Add an error message to pParse->zErrMsg and increment pParse->nErr.
    63 ** The following formatting characters are allowed:
    64 **
    65 **      %s      Insert a string
    66 **      %z      A string that should be freed after use
    67 **      %d      Insert an integer
    68 **      %T      Insert a token
    69 **      %S      Insert the first element of a SrcList
    70 **
    71 ** This function should be used to report any error that occurs whilst
    72 ** compiling an SQL statement (i.e. within sqlite3_prepare()). The
    73 ** last thing the sqlite3_prepare() function does is copy the error
    74 ** stored by this function into the database handle using sqlite3Error().
    75 ** Function sqlite3Error() should be used during statement execution
    76 ** (sqlite3_step() etc.).
    77 */
    78 void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
    79   va_list ap;
    80   pParse->nErr++;
    81   sqlite3_free(pParse->zErrMsg);
    82   va_start(ap, zFormat);
    83   pParse->zErrMsg = sqlite3VMPrintf(pParse->db, zFormat, ap);
    84   va_end(ap);
    85   if( pParse->rc==SQLITE_OK ){
    86     pParse->rc = SQLITE_ERROR;
    87   }
    88 }
    89 
    90 /*
    91 ** Clear the error message in pParse, if any
    92 */
    93 void sqlite3ErrorClear(Parse *pParse){
    94   sqlite3_free(pParse->zErrMsg);
    95   pParse->zErrMsg = 0;
    96   pParse->nErr = 0;
    97 }
    98 
    99 /*
   100 ** Convert an SQL-style quoted string into a normal string by removing
   101 ** the quote characters.  The conversion is done in-place.  If the
   102 ** input does not begin with a quote character, then this routine
   103 ** is a no-op.
   104 **
   105 ** 2002-Feb-14: This routine is extended to remove MS-Access style
   106 ** brackets from around identifers.  For example:  "[a-b-c]" becomes
   107 ** "a-b-c".
   108 */
   109 void sqlite3Dequote(char *z){
   110   int quote;
   111   int i, j;
   112   if( z==0 ) return;
   113   quote = z[0];
   114   switch( quote ){
   115     case '\'':  break;
   116     case '"':   break;
   117     case '`':   break;                /* For MySQL compatibility */
   118     case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */
   119     default:    return;
   120   }
   121   for(i=1, j=0; z[i]; i++){
   122     if( z[i]==quote ){
   123       if( z[i+1]==quote ){
   124         z[j++] = quote;
   125         i++;
   126       }else{
   127         z[j++] = 0;
   128         break;
   129       }
   130     }else{
   131       z[j++] = z[i];
   132     }
   133   }
   134 }
   135 
   136 /* An array to map all upper-case characters into their corresponding
   137 ** lower-case character. 
   138 */
   139 const unsigned char sqlite3UpperToLower[] = {
   140 #ifdef SQLITE_ASCII
   141       0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17,
   142      18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
   143      36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
   144      54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 97, 98, 99,100,101,102,103,
   145     104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,
   146     122, 91, 92, 93, 94, 95, 96, 97, 98, 99,100,101,102,103,104,105,106,107,
   147     108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,
   148     126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,
   149     144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,
   150     162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,
   151     180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,
   152     198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,
   153     216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,
   154     234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,
   155     252,253,254,255
   156 #endif
   157 #ifdef SQLITE_EBCDIC
   158       0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, /* 0x */
   159      16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, /* 1x */
   160      32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, /* 2x */
   161      48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, /* 3x */
   162      64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, /* 4x */
   163      80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, /* 5x */
   164      96, 97, 66, 67, 68, 69, 70, 71, 72, 73,106,107,108,109,110,111, /* 6x */
   165     112, 81, 82, 83, 84, 85, 86, 87, 88, 89,122,123,124,125,126,127, /* 7x */
   166     128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143, /* 8x */
   167     144,145,146,147,148,149,150,151,152,153,154,155,156,157,156,159, /* 9x */
   168     160,161,162,163,164,165,166,167,168,169,170,171,140,141,142,175, /* Ax */
   169     176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191, /* Bx */
   170     192,129,130,131,132,133,134,135,136,137,202,203,204,205,206,207, /* Cx */
   171     208,145,146,147,148,149,150,151,152,153,218,219,220,221,222,223, /* Dx */
   172     224,225,162,163,164,165,166,167,168,169,232,203,204,205,206,207, /* Ex */
   173     239,240,241,242,243,244,245,246,247,248,249,219,220,221,222,255, /* Fx */
   174 #endif
   175 };
   176 #define UpperToLower sqlite3UpperToLower
   177 
   178 /*
   179 ** Some systems have stricmp().  Others have strcasecmp().  Because
   180 ** there is no consistency, we will define our own.
   181 */
   182 int sqlite3StrICmp(const char *zLeft, const char *zRight){
   183   register unsigned char *a, *b;
   184   a = (unsigned char *)zLeft;
   185   b = (unsigned char *)zRight;
   186   while( *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
   187   return UpperToLower[*a] - UpperToLower[*b];
   188 }
   189 int sqlite3StrNICmp(const char *zLeft, const char *zRight, int N){
   190   register unsigned char *a, *b;
   191   a = (unsigned char *)zLeft;
   192   b = (unsigned char *)zRight;
   193   while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
   194   return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
   195 }
   196 
   197 /*
   198 ** Return TRUE if z is a pure numeric string.  Return FALSE if the
   199 ** string contains any character which is not part of a number. If
   200 ** the string is numeric and contains the '.' character, set *realnum
   201 ** to TRUE (otherwise FALSE).
   202 **
   203 ** An empty string is considered non-numeric.
   204 */
   205 int sqlite3IsNumber(const char *z, int *realnum, u8 enc){
   206   int incr = (enc==SQLITE_UTF8?1:2);
   207   if( enc==SQLITE_UTF16BE ) z++;
   208   if( *z=='-' || *z=='+' ) z += incr;
   209   if( !isdigit(*(u8*)z) ){
   210     return 0;
   211   }
   212   z += incr;
   213   if( realnum ) *realnum = 0;
   214   while( isdigit(*(u8*)z) ){ z += incr; }
   215   if( *z=='.' ){
   216     z += incr;
   217     if( !isdigit(*(u8*)z) ) return 0;
   218     while( isdigit(*(u8*)z) ){ z += incr; }
   219     if( realnum ) *realnum = 1;
   220   }
   221   if( *z=='e' || *z=='E' ){
   222     z += incr;
   223     if( *z=='+' || *z=='-' ) z += incr;
   224     if( !isdigit(*(u8*)z) ) return 0;
   225     while( isdigit(*(u8*)z) ){ z += incr; }
   226     if( realnum ) *realnum = 1;
   227   }
   228   return *z==0;
   229 }
   230 
   231 /*
   232 ** The string z[] is an ascii representation of a real number.
   233 ** Convert this string to a double.
   234 **
   235 ** This routine assumes that z[] really is a valid number.  If it
   236 ** is not, the result is undefined.
   237 **
   238 ** This routine is used instead of the library atof() function because
   239 ** the library atof() might want to use "," as the decimal point instead
   240 ** of "." depending on how locale is set.  But that would cause problems
   241 ** for SQL.  So this routine always uses "." regardless of locale.
   242 */
   243 int sqlite3AtoF(const char *z, double *pResult){
   244 #ifndef SQLITE_OMIT_FLOATING_POINT
   245   int sign = 1;
   246   const char *zBegin = z;
   247   LONGDOUBLE_TYPE v1 = 0.0;
   248   while( isspace(*(u8*)z) ) z++;
   249   if( *z=='-' ){
   250     sign = -1;
   251     z++;
   252   }else if( *z=='+' ){
   253     z++;
   254   }
   255   while( isdigit(*(u8*)z) ){
   256     v1 = v1*10.0 + (*z - '0');
   257     z++;
   258   }
   259   if( *z=='.' ){
   260     LONGDOUBLE_TYPE divisor = 1.0;
   261     z++;
   262     while( isdigit(*(u8*)z) ){
   263       v1 = v1*10.0 + (*z - '0');
   264       divisor *= 10.0;
   265       z++;
   266     }
   267     v1 /= divisor;
   268   }
   269   if( *z=='e' || *z=='E' ){
   270     int esign = 1;
   271     int eval = 0;
   272     LONGDOUBLE_TYPE scale = 1.0;
   273     z++;
   274     if( *z=='-' ){
   275       esign = -1;
   276       z++;
   277     }else if( *z=='+' ){
   278       z++;
   279     }
   280     while( isdigit(*(u8*)z) ){
   281       eval = eval*10 + *z - '0';
   282       z++;
   283     }
   284     while( eval>=64 ){ scale *= 1.0e+64; eval -= 64; }
   285     while( eval>=16 ){ scale *= 1.0e+16; eval -= 16; }
   286     while( eval>=4 ){ scale *= 1.0e+4; eval -= 4; }
   287     while( eval>=1 ){ scale *= 1.0e+1; eval -= 1; }
   288     if( esign<0 ){
   289       v1 /= scale;
   290     }else{
   291       v1 *= scale;
   292     }
   293   }
   294   *pResult = sign<0 ? -v1 : v1;
   295   return z - zBegin;
   296 #else
   297   return sqlite3Atoi64(z, pResult);
   298 #endif /* SQLITE_OMIT_FLOATING_POINT */
   299 }
   300 
   301 /*
   302 ** Compare the 19-character string zNum against the text representation
   303 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive
   304 ** if zNum is less than, equal to, or greater than the string.
   305 **
   306 ** Unlike memcmp() this routine is guaranteed to return the difference
   307 ** in the values of the last digit if the only difference is in the
   308 ** last digit.  So, for example,
   309 **
   310 **      compare2pow63("9223372036854775800")
   311 **
   312 ** will return -8.
   313 */
   314 static int compare2pow63(const char *zNum){
   315   int c;
   316   c = memcmp(zNum,"922337203685477580",18);
   317   if( c==0 ){
   318     c = zNum[18] - '8';
   319   }
   320   return c;
   321 }
   322 
   323 
   324 /*
   325 ** Return TRUE if zNum is a 64-bit signed integer and write
   326 ** the value of the integer into *pNum.  If zNum is not an integer
   327 ** or is an integer that is too large to be expressed with 64 bits,
   328 ** then return false.
   329 **
   330 ** When this routine was originally written it dealt with only
   331 ** 32-bit numbers.  At that time, it was much faster than the
   332 ** atoi() library routine in RedHat 7.2.
   333 */
   334 int sqlite3Atoi64(const char *zNum, i64 *pNum){
   335   i64 v = 0;
   336   int neg;
   337   int i, c;
   338   while( isspace(*(u8*)zNum) ) zNum++;
   339   if( *zNum=='-' ){
   340     neg = 1;
   341     zNum++;
   342   }else if( *zNum=='+' ){
   343     neg = 0;
   344     zNum++;
   345   }else{
   346     neg = 0;
   347   }
   348   while( zNum[0]=='0' ){ zNum++; } /* Skip over leading zeros. Ticket #2454 */
   349   for(i=0; (c=zNum[i])>='0' && c<='9'; i++){
   350     v = v*10 + c - '0';
   351   }
   352   *pNum = neg ? -v : v;
   353   if( c!=0 || i==0 || i>19 ){
   354     /* zNum is empty or contains non-numeric text or is longer
   355     ** than 19 digits (thus guaranting that it is too large) */
   356     return 0;
   357   }else if( i<19 ){
   358     /* Less than 19 digits, so we know that it fits in 64 bits */
   359     return 1;
   360   }else{
   361     /* 19-digit numbers must be no larger than 9223372036854775807 if positive
   362     ** or 9223372036854775808 if negative.  Note that 9223372036854665808
   363     ** is 2^63. */
   364     return compare2pow63(zNum)<neg;
   365   }
   366 }
   367 
   368 /*
   369 ** The string zNum represents an integer.  There might be some other
   370 ** information following the integer too, but that part is ignored.
   371 ** If the integer that the prefix of zNum represents will fit in a
   372 ** 64-bit signed integer, return TRUE.  Otherwise return FALSE.
   373 **
   374 ** This routine returns FALSE for the string -9223372036854775808 even that
   375 ** that number will, in theory fit in a 64-bit integer.  Positive
   376 ** 9223373036854775808 will not fit in 64 bits.  So it seems safer to return
   377 ** false.
   378 */
   379 int sqlite3FitsIn64Bits(const char *zNum){
   380   int i, c;
   381   int neg = 0;
   382   if( *zNum=='-' ){
   383     neg = 1;
   384     zNum++;
   385   }else if( *zNum=='+' ){
   386     zNum++;
   387   }
   388   while( *zNum=='0' ){
   389     zNum++;   /* Skip leading zeros.  Ticket #2454 */
   390   }
   391   for(i=0; (c=zNum[i])>='0' && c<='9'; i++){}
   392   if( i<19 ){
   393     /* Guaranteed to fit if less than 19 digits */
   394     return 1;
   395   }else if( i>19 ){
   396     /* Guaranteed to be too big if greater than 19 digits */
   397     return 0;
   398   }else{
   399     /* Compare against 2^63. */
   400     return compare2pow63(zNum)<neg;
   401   }
   402 }
   403 
   404 /*
   405 ** If zNum represents an integer that will fit in 32-bits, then set
   406 ** *pValue to that integer and return true.  Otherwise return false.
   407 **
   408 ** Any non-numeric characters that following zNum are ignored.
   409 ** This is different from sqlite3Atoi64() which requires the
   410 ** input number to be zero-terminated.
   411 */
   412 int sqlite3GetInt32(const char *zNum, int *pValue){
   413   sqlite_int64 v = 0;
   414   int i, c;
   415   int neg = 0;
   416   if( zNum[0]=='-' ){
   417     neg = 1;
   418     zNum++;
   419   }else if( zNum[0]=='+' ){
   420     zNum++;
   421   }
   422   while( zNum[0]=='0' ) zNum++;
   423   for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
   424     v = v*10 + c;
   425   }
   426 
   427   /* The longest decimal representation of a 32 bit integer is 10 digits:
   428   **
   429   **             1234567890
   430   **     2^31 -> 2147483648
   431   */
   432   if( i>10 ){
   433     return 0;
   434   }
   435   if( v-neg>2147483647 ){
   436     return 0;
   437   }
   438   if( neg ){
   439     v = -v;
   440   }
   441   *pValue = (int)v;
   442   return 1;
   443 }
   444 
   445 /*
   446 ** Check to make sure we have a valid db pointer.  This test is not
   447 ** foolproof but it does provide some measure of protection against
   448 ** misuse of the interface such as passing in db pointers that are
   449 ** NULL or which have been previously closed.  If this routine returns
   450 ** TRUE it means that the db pointer is invalid and should not be
   451 ** dereferenced for any reason.  The calling function should invoke
   452 ** SQLITE_MISUSE immediately.
   453 */
   454 int sqlite3SafetyCheck(sqlite3 *db){
   455   int magic;
   456   if( db==0 ) return 1;
   457   magic = db->magic;
   458   if( magic!=SQLITE_MAGIC_CLOSED &&
   459          magic!=SQLITE_MAGIC_OPEN &&
   460          magic!=SQLITE_MAGIC_BUSY ) return 1;
   461   return 0;
   462 }
   463 
   464 /*
   465 ** The variable-length integer encoding is as follows:
   466 **
   467 ** KEY:
   468 **         A = 0xxxxxxx    7 bits of data and one flag bit
   469 **         B = 1xxxxxxx    7 bits of data and one flag bit
   470 **         C = xxxxxxxx    8 bits of data
   471 **
   472 **  7 bits - A
   473 ** 14 bits - BA
   474 ** 21 bits - BBA
   475 ** 28 bits - BBBA
   476 ** 35 bits - BBBBA
   477 ** 42 bits - BBBBBA
   478 ** 49 bits - BBBBBBA
   479 ** 56 bits - BBBBBBBA
   480 ** 64 bits - BBBBBBBBC
   481 */
   482 
   483 /*
   484 ** Write a 64-bit variable-length integer to memory starting at p[0].
   485 ** The length of data write will be between 1 and 9 bytes.  The number
   486 ** of bytes written is returned.
   487 **
   488 ** A variable-length integer consists of the lower 7 bits of each byte
   489 ** for all bytes that have the 8th bit set and one byte with the 8th
   490 ** bit clear.  Except, if we get to the 9th byte, it stores the full
   491 ** 8 bits and is the last byte.
   492 */
   493 int sqlite3PutVarint(unsigned char *p, u64 v){
   494   int i, j, n;
   495   u8 buf[10];
   496   if( v & (((u64)0xff000000)<<32) ){
   497     p[8] = v;
   498     v >>= 8;
   499     for(i=7; i>=0; i--){
   500       p[i] = (v & 0x7f) | 0x80;
   501       v >>= 7;
   502     }
   503     return 9;
   504   }    
   505   n = 0;
   506   do{
   507     buf[n++] = (v & 0x7f) | 0x80;
   508     v >>= 7;
   509   }while( v!=0 );
   510   buf[0] &= 0x7f;
   511   assert( n<=9 );
   512   for(i=0, j=n-1; j>=0; j--, i++){
   513     p[i] = buf[j];
   514   }
   515   return n;
   516 }
   517 
   518 /*
   519 ** Read a 64-bit variable-length integer from memory starting at p[0].
   520 ** Return the number of bytes read.  The value is stored in *v.
   521 */
   522 int sqlite3GetVarint(const unsigned char *p, u64 *v){
   523   u32 x;
   524   u64 x64;
   525   int n;
   526   unsigned char c;
   527   if( ((c = p[0]) & 0x80)==0 ){
   528     *v = c;
   529     return 1;
   530   }
   531   x = c & 0x7f;
   532   if( ((c = p[1]) & 0x80)==0 ){
   533     *v = (x<<7) | c;
   534     return 2;
   535   }
   536   x = (x<<7) | (c&0x7f);
   537   if( ((c = p[2]) & 0x80)==0 ){
   538     *v = (x<<7) | c;
   539     return 3;
   540   }
   541   x = (x<<7) | (c&0x7f);
   542   if( ((c = p[3]) & 0x80)==0 ){
   543     *v = (x<<7) | c;
   544     return 4;
   545   }
   546   x64 = (x<<7) | (c&0x7f);
   547   n = 4;
   548   do{
   549     c = p[n++];
   550     if( n==9 ){
   551       x64 = (x64<<8) | c;
   552       break;
   553     }
   554     x64 = (x64<<7) | (c&0x7f);
   555   }while( (c & 0x80)!=0 );
   556   *v = x64;
   557   return n;
   558 }
   559 
   560 /*
   561 ** Read a 32-bit variable-length integer from memory starting at p[0].
   562 ** Return the number of bytes read.  The value is stored in *v.
   563 */
   564 int sqlite3GetVarint32(const unsigned char *p, u32 *v){
   565   u32 x;
   566   int n;
   567   unsigned char c;
   568   if( ((signed char*)p)[0]>=0 ){
   569     *v = p[0];
   570     return 1;
   571   }
   572   x = p[0] & 0x7f;
   573   if( ((signed char*)p)[1]>=0 ){
   574     *v = (x<<7) | p[1];
   575     return 2;
   576   }
   577   x = (x<<7) | (p[1] & 0x7f);
   578   n = 2;
   579   do{
   580     x = (x<<7) | ((c = p[n++])&0x7f);
   581   }while( (c & 0x80)!=0 && n<9 );
   582   *v = x;
   583   return n;
   584 }
   585 
   586 /*
   587 ** Return the number of bytes that will be needed to store the given
   588 ** 64-bit integer.
   589 */
   590 int sqlite3VarintLen(u64 v){
   591   int i = 0;
   592   do{
   593     i++;
   594     v >>= 7;
   595   }while( v!=0 && i<9 );
   596   return i;
   597 }
   598 
   599 
   600 /*
   601 ** Read or write a four-byte big-endian integer value.
   602 */
   603 u32 sqlite3Get4byte(const u8 *p){
   604   return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
   605 }
   606 void sqlite3Put4byte(unsigned char *p, u32 v){
   607   p[0] = v>>24;
   608   p[1] = v>>16;
   609   p[2] = v>>8;
   610   p[3] = v;
   611 }
   612 
   613 
   614 
   615 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC) \
   616     || defined(SQLITE_TEST)
   617 /*
   618 ** Translate a single byte of Hex into an integer.
   619 */
   620 static int hexToInt(int h){
   621   if( h>='0' && h<='9' ){
   622     return h - '0';
   623   }else if( h>='a' && h<='f' ){
   624     return h - 'a' + 10;
   625   }else{
   626     assert( h>='A' && h<='F' );
   627     return h - 'A' + 10;
   628   }
   629 }
   630 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC || SQLITE_TEST */
   631 
   632 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
   633 /*
   634 ** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
   635 ** value.  Return a pointer to its binary value.  Space to hold the
   636 ** binary value has been obtained from malloc and must be freed by
   637 ** the calling routine.
   638 */
   639 void *sqlite3HexToBlob(sqlite3 *db, const char *z){
   640   char *zBlob;
   641   int i;
   642   int n = strlen(z);
   643   if( n%2 ) return 0;
   644 
   645   zBlob = (char *)sqlite3DbMallocRaw(db, n/2);
   646   if( zBlob ){
   647     for(i=0; i<n; i+=2){
   648       zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);
   649     }
   650   }
   651   return zBlob;
   652 }
   653 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
   654 
   655 
   656 /*
   657 ** Change the sqlite.magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.
   658 ** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN
   659 ** when this routine is called.
   660 **
   661 ** This routine is called when entering an SQLite API.  The SQLITE_MAGIC_OPEN
   662 ** value indicates that the database connection passed into the API is
   663 ** open and is not being used by another thread.  By changing the value
   664 ** to SQLITE_MAGIC_BUSY we indicate that the connection is in use.
   665 ** sqlite3SafetyOff() below will change the value back to SQLITE_MAGIC_OPEN
   666 ** when the API exits. 
   667 **
   668 ** This routine is a attempt to detect if two threads use the
   669 ** same sqlite* pointer at the same time.  There is a race 
   670 ** condition so it is possible that the error is not detected.
   671 ** But usually the problem will be seen.  The result will be an
   672 ** error which can be used to debug the application that is
   673 ** using SQLite incorrectly.
   674 **
   675 ** Ticket #202:  If db->magic is not a valid open value, take care not
   676 ** to modify the db structure at all.  It could be that db is a stale
   677 ** pointer.  In other words, it could be that there has been a prior
   678 ** call to sqlite3_close(db) and db has been deallocated.  And we do
   679 ** not want to write into deallocated memory.
   680 */
   681 int sqlite3SafetyOn(sqlite3 *db){
   682   if( db->magic==SQLITE_MAGIC_OPEN ){
   683     db->magic = SQLITE_MAGIC_BUSY;
   684     return 0;
   685   }else if( db->magic==SQLITE_MAGIC_BUSY ){
   686     db->magic = SQLITE_MAGIC_ERROR;
   687     db->u1.isInterrupted = 1;
   688   }
   689   return 1;
   690 }
   691 
   692 /*
   693 ** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.
   694 ** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY
   695 ** when this routine is called.
   696 */
   697 int sqlite3SafetyOff(sqlite3 *db){
   698   if( db->magic==SQLITE_MAGIC_BUSY ){
   699     db->magic = SQLITE_MAGIC_OPEN;
   700     return 0;
   701   }else {
   702     db->magic = SQLITE_MAGIC_ERROR;
   703     db->u1.isInterrupted = 1;
   704     return 1;
   705   }
   706 }