xref: /sqlite-3.40.0/src/util.c (revision fd779e2f)
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 */
18 #include "sqliteInt.h"
19 #include <stdarg.h>
20 #ifndef SQLITE_OMIT_FLOATING_POINT
21 #include <math.h>
22 #endif
23 
24 /*
25 ** Routine needed to support the testcase() macro.
26 */
27 #ifdef SQLITE_COVERAGE_TEST
28 void sqlite3Coverage(int x){
29   static unsigned dummy = 0;
30   dummy += (unsigned)x;
31 }
32 #endif
33 
34 /*
35 ** Calls to sqlite3FaultSim() are used to simulate a failure during testing,
36 ** or to bypass normal error detection during testing in order to let
37 ** execute proceed futher downstream.
38 **
39 ** In deployment, sqlite3FaultSim() *always* return SQLITE_OK (0).  The
40 ** sqlite3FaultSim() function only returns non-zero during testing.
41 **
42 ** During testing, if the test harness has set a fault-sim callback using
43 ** a call to sqlite3_test_control(SQLITE_TESTCTRL_FAULT_INSTALL), then
44 ** each call to sqlite3FaultSim() is relayed to that application-supplied
45 ** callback and the integer return value form the application-supplied
46 ** callback is returned by sqlite3FaultSim().
47 **
48 ** The integer argument to sqlite3FaultSim() is a code to identify which
49 ** sqlite3FaultSim() instance is being invoked. Each call to sqlite3FaultSim()
50 ** should have a unique code.  To prevent legacy testing applications from
51 ** breaking, the codes should not be changed or reused.
52 */
53 #ifndef SQLITE_UNTESTABLE
54 int sqlite3FaultSim(int iTest){
55   int (*xCallback)(int) = sqlite3GlobalConfig.xTestCallback;
56   return xCallback ? xCallback(iTest) : SQLITE_OK;
57 }
58 #endif
59 
60 #ifndef SQLITE_OMIT_FLOATING_POINT
61 /*
62 ** Return true if the floating point value is Not a Number (NaN).
63 */
64 int sqlite3IsNaN(double x){
65   u64 y;
66   memcpy(&y,&x,sizeof(y));
67   return IsNaN(y);
68 }
69 #endif /* SQLITE_OMIT_FLOATING_POINT */
70 
71 /*
72 ** Compute a string length that is limited to what can be stored in
73 ** lower 30 bits of a 32-bit signed integer.
74 **
75 ** The value returned will never be negative.  Nor will it ever be greater
76 ** than the actual length of the string.  For very long strings (greater
77 ** than 1GiB) the value returned might be less than the true string length.
78 */
79 int sqlite3Strlen30(const char *z){
80   if( z==0 ) return 0;
81   return 0x3fffffff & (int)strlen(z);
82 }
83 
84 /*
85 ** Return the declared type of a column.  Or return zDflt if the column
86 ** has no declared type.
87 **
88 ** The column type is an extra string stored after the zero-terminator on
89 ** the column name if and only if the COLFLAG_HASTYPE flag is set.
90 */
91 char *sqlite3ColumnType(Column *pCol, char *zDflt){
92   if( pCol->colFlags & COLFLAG_HASTYPE ){
93     return pCol->zCnName + strlen(pCol->zCnName) + 1;
94   }else if( pCol->eType ){
95     assert( pCol->eType<=SQLITE_N_STDTYPE );
96     return (char*)sqlite3StdType[pCol->eType-1];
97   }else{
98     return zDflt;
99   }
100 }
101 
102 /*
103 ** Helper function for sqlite3Error() - called rarely.  Broken out into
104 ** a separate routine to avoid unnecessary register saves on entry to
105 ** sqlite3Error().
106 */
107 static SQLITE_NOINLINE void  sqlite3ErrorFinish(sqlite3 *db, int err_code){
108   if( db->pErr ) sqlite3ValueSetNull(db->pErr);
109   sqlite3SystemError(db, err_code);
110 }
111 
112 /*
113 ** Set the current error code to err_code and clear any prior error message.
114 ** Also set iSysErrno (by calling sqlite3System) if the err_code indicates
115 ** that would be appropriate.
116 */
117 void sqlite3Error(sqlite3 *db, int err_code){
118   assert( db!=0 );
119   db->errCode = err_code;
120   if( err_code || db->pErr ) sqlite3ErrorFinish(db, err_code);
121 }
122 
123 /*
124 ** The equivalent of sqlite3Error(db, SQLITE_OK).  Clear the error state
125 ** and error message.
126 */
127 void sqlite3ErrorClear(sqlite3 *db){
128   assert( db!=0 );
129   db->errCode = SQLITE_OK;
130   if( db->pErr ) sqlite3ValueSetNull(db->pErr);
131 }
132 
133 /*
134 ** Load the sqlite3.iSysErrno field if that is an appropriate thing
135 ** to do based on the SQLite error code in rc.
136 */
137 void sqlite3SystemError(sqlite3 *db, int rc){
138   if( rc==SQLITE_IOERR_NOMEM ) return;
139   rc &= 0xff;
140   if( rc==SQLITE_CANTOPEN || rc==SQLITE_IOERR ){
141     db->iSysErrno = sqlite3OsGetLastError(db->pVfs);
142   }
143 }
144 
145 /*
146 ** Set the most recent error code and error string for the sqlite
147 ** handle "db". The error code is set to "err_code".
148 **
149 ** If it is not NULL, string zFormat specifies the format of the
150 ** error string in the style of the printf functions: The following
151 ** format characters are allowed:
152 **
153 **      %s      Insert a string
154 **      %z      A string that should be freed after use
155 **      %d      Insert an integer
156 **      %T      Insert a token
157 **      %S      Insert the first element of a SrcList
158 **
159 ** zFormat and any string tokens that follow it are assumed to be
160 ** encoded in UTF-8.
161 **
162 ** To clear the most recent error for sqlite handle "db", sqlite3Error
163 ** should be called with err_code set to SQLITE_OK and zFormat set
164 ** to NULL.
165 */
166 void sqlite3ErrorWithMsg(sqlite3 *db, int err_code, const char *zFormat, ...){
167   assert( db!=0 );
168   db->errCode = err_code;
169   sqlite3SystemError(db, err_code);
170   if( zFormat==0 ){
171     sqlite3Error(db, err_code);
172   }else if( db->pErr || (db->pErr = sqlite3ValueNew(db))!=0 ){
173     char *z;
174     va_list ap;
175     va_start(ap, zFormat);
176     z = sqlite3VMPrintf(db, zFormat, ap);
177     va_end(ap);
178     sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
179   }
180 }
181 
182 /*
183 ** Add an error message to pParse->zErrMsg and increment pParse->nErr.
184 ** The following formatting characters are allowed:
185 **
186 **      %s      Insert a string
187 **      %z      A string that should be freed after use
188 **      %d      Insert an integer
189 **      %T      Insert a token
190 **      %S      Insert the first element of a SrcList
191 **
192 ** This function should be used to report any error that occurs while
193 ** compiling an SQL statement (i.e. within sqlite3_prepare()). The
194 ** last thing the sqlite3_prepare() function does is copy the error
195 ** stored by this function into the database handle using sqlite3Error().
196 ** Functions sqlite3Error() or sqlite3ErrorWithMsg() should be used
197 ** during statement execution (sqlite3_step() etc.).
198 */
199 void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
200   char *zMsg;
201   va_list ap;
202   sqlite3 *db = pParse->db;
203   va_start(ap, zFormat);
204   zMsg = sqlite3VMPrintf(db, zFormat, ap);
205   va_end(ap);
206   if( db->suppressErr ){
207     sqlite3DbFree(db, zMsg);
208   }else{
209     pParse->nErr++;
210     sqlite3DbFree(db, pParse->zErrMsg);
211     pParse->zErrMsg = zMsg;
212     pParse->rc = SQLITE_ERROR;
213     pParse->pWith = 0;
214   }
215 }
216 
217 /*
218 ** If database connection db is currently parsing SQL, then transfer
219 ** error code errCode to that parser if the parser has not already
220 ** encountered some other kind of error.
221 */
222 int sqlite3ErrorToParser(sqlite3 *db, int errCode){
223   Parse *pParse;
224   if( db==0 || (pParse = db->pParse)==0 ) return errCode;
225   pParse->rc = errCode;
226   pParse->nErr++;
227   return errCode;
228 }
229 
230 /*
231 ** Convert an SQL-style quoted string into a normal string by removing
232 ** the quote characters.  The conversion is done in-place.  If the
233 ** input does not begin with a quote character, then this routine
234 ** is a no-op.
235 **
236 ** The input string must be zero-terminated.  A new zero-terminator
237 ** is added to the dequoted string.
238 **
239 ** The return value is -1 if no dequoting occurs or the length of the
240 ** dequoted string, exclusive of the zero terminator, if dequoting does
241 ** occur.
242 **
243 ** 2002-02-14: This routine is extended to remove MS-Access style
244 ** brackets from around identifiers.  For example:  "[a-b-c]" becomes
245 ** "a-b-c".
246 */
247 void sqlite3Dequote(char *z){
248   char quote;
249   int i, j;
250   if( z==0 ) return;
251   quote = z[0];
252   if( !sqlite3Isquote(quote) ) return;
253   if( quote=='[' ) quote = ']';
254   for(i=1, j=0;; i++){
255     assert( z[i] );
256     if( z[i]==quote ){
257       if( z[i+1]==quote ){
258         z[j++] = quote;
259         i++;
260       }else{
261         break;
262       }
263     }else{
264       z[j++] = z[i];
265     }
266   }
267   z[j] = 0;
268 }
269 void sqlite3DequoteExpr(Expr *p){
270   assert( sqlite3Isquote(p->u.zToken[0]) );
271   p->flags |= p->u.zToken[0]=='"' ? EP_Quoted|EP_DblQuoted : EP_Quoted;
272   sqlite3Dequote(p->u.zToken);
273 }
274 
275 /*
276 ** If the input token p is quoted, try to adjust the token to remove
277 ** the quotes.  This is not always possible:
278 **
279 **     "abc"     ->   abc
280 **     "ab""cd"  ->   (not possible because of the interior "")
281 **
282 ** Remove the quotes if possible.  This is a optimization.  The overall
283 ** system should still return the correct answer even if this routine
284 ** is always a no-op.
285 */
286 void sqlite3DequoteToken(Token *p){
287   int i;
288   if( p->n<2 ) return;
289   if( !sqlite3Isquote(p->z[0]) ) return;
290   for(i=1; i<p->n-1; i++){
291     if( sqlite3Isquote(p->z[i]) ) return;
292   }
293   p->n -= 2;
294   p->z++;
295 }
296 
297 /*
298 ** Generate a Token object from a string
299 */
300 void sqlite3TokenInit(Token *p, char *z){
301   p->z = z;
302   p->n = sqlite3Strlen30(z);
303 }
304 
305 /* Convenient short-hand */
306 #define UpperToLower sqlite3UpperToLower
307 
308 /*
309 ** Some systems have stricmp().  Others have strcasecmp().  Because
310 ** there is no consistency, we will define our own.
311 **
312 ** IMPLEMENTATION-OF: R-30243-02494 The sqlite3_stricmp() and
313 ** sqlite3_strnicmp() APIs allow applications and extensions to compare
314 ** the contents of two buffers containing UTF-8 strings in a
315 ** case-independent fashion, using the same definition of "case
316 ** independence" that SQLite uses internally when comparing identifiers.
317 */
318 int sqlite3_stricmp(const char *zLeft, const char *zRight){
319   if( zLeft==0 ){
320     return zRight ? -1 : 0;
321   }else if( zRight==0 ){
322     return 1;
323   }
324   return sqlite3StrICmp(zLeft, zRight);
325 }
326 int sqlite3StrICmp(const char *zLeft, const char *zRight){
327   unsigned char *a, *b;
328   int c, x;
329   a = (unsigned char *)zLeft;
330   b = (unsigned char *)zRight;
331   for(;;){
332     c = *a;
333     x = *b;
334     if( c==x ){
335       if( c==0 ) break;
336     }else{
337       c = (int)UpperToLower[c] - (int)UpperToLower[x];
338       if( c ) break;
339     }
340     a++;
341     b++;
342   }
343   return c;
344 }
345 int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
346   register unsigned char *a, *b;
347   if( zLeft==0 ){
348     return zRight ? -1 : 0;
349   }else if( zRight==0 ){
350     return 1;
351   }
352   a = (unsigned char *)zLeft;
353   b = (unsigned char *)zRight;
354   while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
355   return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
356 }
357 
358 /*
359 ** Compute an 8-bit hash on a string that is insensitive to case differences
360 */
361 u8 sqlite3StrIHash(const char *z){
362   u8 h = 0;
363   if( z==0 ) return 0;
364   while( z[0] ){
365     h += UpperToLower[(unsigned char)z[0]];
366     z++;
367   }
368   return h;
369 }
370 
371 /*
372 ** Compute 10 to the E-th power.  Examples:  E==1 results in 10.
373 ** E==2 results in 100.  E==50 results in 1.0e50.
374 **
375 ** This routine only works for values of E between 1 and 341.
376 */
377 static LONGDOUBLE_TYPE sqlite3Pow10(int E){
378 #if defined(_MSC_VER)
379   static const LONGDOUBLE_TYPE x[] = {
380     1.0e+001L,
381     1.0e+002L,
382     1.0e+004L,
383     1.0e+008L,
384     1.0e+016L,
385     1.0e+032L,
386     1.0e+064L,
387     1.0e+128L,
388     1.0e+256L
389   };
390   LONGDOUBLE_TYPE r = 1.0;
391   int i;
392   assert( E>=0 && E<=307 );
393   for(i=0; E!=0; i++, E >>=1){
394     if( E & 1 ) r *= x[i];
395   }
396   return r;
397 #else
398   LONGDOUBLE_TYPE x = 10.0;
399   LONGDOUBLE_TYPE r = 1.0;
400   while(1){
401     if( E & 1 ) r *= x;
402     E >>= 1;
403     if( E==0 ) break;
404     x *= x;
405   }
406   return r;
407 #endif
408 }
409 
410 /*
411 ** The string z[] is an text representation of a real number.
412 ** Convert this string to a double and write it into *pResult.
413 **
414 ** The string z[] is length bytes in length (bytes, not characters) and
415 ** uses the encoding enc.  The string is not necessarily zero-terminated.
416 **
417 ** Return TRUE if the result is a valid real number (or integer) and FALSE
418 ** if the string is empty or contains extraneous text.  More specifically
419 ** return
420 **      1          =>  The input string is a pure integer
421 **      2 or more  =>  The input has a decimal point or eNNN clause
422 **      0 or less  =>  The input string is not a valid number
423 **     -1          =>  Not a valid number, but has a valid prefix which
424 **                     includes a decimal point and/or an eNNN clause
425 **
426 ** Valid numbers are in one of these formats:
427 **
428 **    [+-]digits[E[+-]digits]
429 **    [+-]digits.[digits][E[+-]digits]
430 **    [+-].digits[E[+-]digits]
431 **
432 ** Leading and trailing whitespace is ignored for the purpose of determining
433 ** validity.
434 **
435 ** If some prefix of the input string is a valid number, this routine
436 ** returns FALSE but it still converts the prefix and writes the result
437 ** into *pResult.
438 */
439 #if defined(_MSC_VER)
440 #pragma warning(disable : 4756)
441 #endif
442 int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
443 #ifndef SQLITE_OMIT_FLOATING_POINT
444   int incr;
445   const char *zEnd;
446   /* sign * significand * (10 ^ (esign * exponent)) */
447   int sign = 1;    /* sign of significand */
448   i64 s = 0;       /* significand */
449   int d = 0;       /* adjust exponent for shifting decimal point */
450   int esign = 1;   /* sign of exponent */
451   int e = 0;       /* exponent */
452   int eValid = 1;  /* True exponent is either not used or is well-formed */
453   double result;
454   int nDigit = 0;  /* Number of digits processed */
455   int eType = 1;   /* 1: pure integer,  2+: fractional  -1 or less: bad UTF16 */
456 
457   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
458   *pResult = 0.0;   /* Default return value, in case of an error */
459   if( length==0 ) return 0;
460 
461   if( enc==SQLITE_UTF8 ){
462     incr = 1;
463     zEnd = z + length;
464   }else{
465     int i;
466     incr = 2;
467     length &= ~1;
468     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
469     testcase( enc==SQLITE_UTF16LE );
470     testcase( enc==SQLITE_UTF16BE );
471     for(i=3-enc; i<length && z[i]==0; i+=2){}
472     if( i<length ) eType = -100;
473     zEnd = &z[i^1];
474     z += (enc&1);
475   }
476 
477   /* skip leading spaces */
478   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
479   if( z>=zEnd ) return 0;
480 
481   /* get sign of significand */
482   if( *z=='-' ){
483     sign = -1;
484     z+=incr;
485   }else if( *z=='+' ){
486     z+=incr;
487   }
488 
489   /* copy max significant digits to significand */
490   while( z<zEnd && sqlite3Isdigit(*z) ){
491     s = s*10 + (*z - '0');
492     z+=incr; nDigit++;
493     if( s>=((LARGEST_INT64-9)/10) ){
494       /* skip non-significant significand digits
495       ** (increase exponent by d to shift decimal left) */
496       while( z<zEnd && sqlite3Isdigit(*z) ){ z+=incr; d++; }
497     }
498   }
499   if( z>=zEnd ) goto do_atof_calc;
500 
501   /* if decimal point is present */
502   if( *z=='.' ){
503     z+=incr;
504     eType++;
505     /* copy digits from after decimal to significand
506     ** (decrease exponent by d to shift decimal right) */
507     while( z<zEnd && sqlite3Isdigit(*z) ){
508       if( s<((LARGEST_INT64-9)/10) ){
509         s = s*10 + (*z - '0');
510         d--;
511         nDigit++;
512       }
513       z+=incr;
514     }
515   }
516   if( z>=zEnd ) goto do_atof_calc;
517 
518   /* if exponent is present */
519   if( *z=='e' || *z=='E' ){
520     z+=incr;
521     eValid = 0;
522     eType++;
523 
524     /* This branch is needed to avoid a (harmless) buffer overread.  The
525     ** special comment alerts the mutation tester that the correct answer
526     ** is obtained even if the branch is omitted */
527     if( z>=zEnd ) goto do_atof_calc;              /*PREVENTS-HARMLESS-OVERREAD*/
528 
529     /* get sign of exponent */
530     if( *z=='-' ){
531       esign = -1;
532       z+=incr;
533     }else if( *z=='+' ){
534       z+=incr;
535     }
536     /* copy digits to exponent */
537     while( z<zEnd && sqlite3Isdigit(*z) ){
538       e = e<10000 ? (e*10 + (*z - '0')) : 10000;
539       z+=incr;
540       eValid = 1;
541     }
542   }
543 
544   /* skip trailing spaces */
545   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
546 
547 do_atof_calc:
548   /* adjust exponent by d, and update sign */
549   e = (e*esign) + d;
550   if( e<0 ) {
551     esign = -1;
552     e *= -1;
553   } else {
554     esign = 1;
555   }
556 
557   if( s==0 ) {
558     /* In the IEEE 754 standard, zero is signed. */
559     result = sign<0 ? -(double)0 : (double)0;
560   } else {
561     /* Attempt to reduce exponent.
562     **
563     ** Branches that are not required for the correct answer but which only
564     ** help to obtain the correct answer faster are marked with special
565     ** comments, as a hint to the mutation tester.
566     */
567     while( e>0 ){                                       /*OPTIMIZATION-IF-TRUE*/
568       if( esign>0 ){
569         if( s>=(LARGEST_INT64/10) ) break;             /*OPTIMIZATION-IF-FALSE*/
570         s *= 10;
571       }else{
572         if( s%10!=0 ) break;                           /*OPTIMIZATION-IF-FALSE*/
573         s /= 10;
574       }
575       e--;
576     }
577 
578     /* adjust the sign of significand */
579     s = sign<0 ? -s : s;
580 
581     if( e==0 ){                                         /*OPTIMIZATION-IF-TRUE*/
582       result = (double)s;
583     }else{
584       /* attempt to handle extremely small/large numbers better */
585       if( e>307 ){                                      /*OPTIMIZATION-IF-TRUE*/
586         if( e<342 ){                                    /*OPTIMIZATION-IF-TRUE*/
587           LONGDOUBLE_TYPE scale = sqlite3Pow10(e-308);
588           if( esign<0 ){
589             result = s / scale;
590             result /= 1.0e+308;
591           }else{
592             result = s * scale;
593             result *= 1.0e+308;
594           }
595         }else{ assert( e>=342 );
596           if( esign<0 ){
597             result = 0.0*s;
598           }else{
599 #ifdef INFINITY
600             result = INFINITY*s;
601 #else
602             result = 1e308*1e308*s;  /* Infinity */
603 #endif
604           }
605         }
606       }else{
607         LONGDOUBLE_TYPE scale = sqlite3Pow10(e);
608         if( esign<0 ){
609           result = s / scale;
610         }else{
611           result = s * scale;
612         }
613       }
614     }
615   }
616 
617   /* store the result */
618   *pResult = result;
619 
620   /* return true if number and no extra non-whitespace chracters after */
621   if( z==zEnd && nDigit>0 && eValid && eType>0 ){
622     return eType;
623   }else if( eType>=2 && (eType==3 || eValid) && nDigit>0 ){
624     return -1;
625   }else{
626     return 0;
627   }
628 #else
629   return !sqlite3Atoi64(z, pResult, length, enc);
630 #endif /* SQLITE_OMIT_FLOATING_POINT */
631 }
632 #if defined(_MSC_VER)
633 #pragma warning(default : 4756)
634 #endif
635 
636 /*
637 ** Render an signed 64-bit integer as text.  Store the result in zOut[].
638 **
639 ** The caller must ensure that zOut[] is at least 21 bytes in size.
640 */
641 void sqlite3Int64ToText(i64 v, char *zOut){
642   int i;
643   u64 x;
644   char zTemp[22];
645   if( v<0 ){
646     x = (v==SMALLEST_INT64) ? ((u64)1)<<63 : (u64)-v;
647   }else{
648     x = v;
649   }
650   i = sizeof(zTemp)-2;
651   zTemp[sizeof(zTemp)-1] = 0;
652   do{
653     zTemp[i--] = (x%10) + '0';
654     x = x/10;
655   }while( x );
656   if( v<0 ) zTemp[i--] = '-';
657   memcpy(zOut, &zTemp[i+1], sizeof(zTemp)-1-i);
658 }
659 
660 /*
661 ** Compare the 19-character string zNum against the text representation
662 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive
663 ** if zNum is less than, equal to, or greater than the string.
664 ** Note that zNum must contain exactly 19 characters.
665 **
666 ** Unlike memcmp() this routine is guaranteed to return the difference
667 ** in the values of the last digit if the only difference is in the
668 ** last digit.  So, for example,
669 **
670 **      compare2pow63("9223372036854775800", 1)
671 **
672 ** will return -8.
673 */
674 static int compare2pow63(const char *zNum, int incr){
675   int c = 0;
676   int i;
677                     /* 012345678901234567 */
678   const char *pow63 = "922337203685477580";
679   for(i=0; c==0 && i<18; i++){
680     c = (zNum[i*incr]-pow63[i])*10;
681   }
682   if( c==0 ){
683     c = zNum[18*incr] - '8';
684     testcase( c==(-1) );
685     testcase( c==0 );
686     testcase( c==(+1) );
687   }
688   return c;
689 }
690 
691 /*
692 ** Convert zNum to a 64-bit signed integer.  zNum must be decimal. This
693 ** routine does *not* accept hexadecimal notation.
694 **
695 ** Returns:
696 **
697 **    -1    Not even a prefix of the input text looks like an integer
698 **     0    Successful transformation.  Fits in a 64-bit signed integer.
699 **     1    Excess non-space text after the integer value
700 **     2    Integer too large for a 64-bit signed integer or is malformed
701 **     3    Special case of 9223372036854775808
702 **
703 ** length is the number of bytes in the string (bytes, not characters).
704 ** The string is not necessarily zero-terminated.  The encoding is
705 ** given by enc.
706 */
707 int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
708   int incr;
709   u64 u = 0;
710   int neg = 0; /* assume positive */
711   int i;
712   int c = 0;
713   int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
714   int rc;          /* Baseline return code */
715   const char *zStart;
716   const char *zEnd = zNum + length;
717   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
718   if( enc==SQLITE_UTF8 ){
719     incr = 1;
720   }else{
721     incr = 2;
722     length &= ~1;
723     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
724     for(i=3-enc; i<length && zNum[i]==0; i+=2){}
725     nonNum = i<length;
726     zEnd = &zNum[i^1];
727     zNum += (enc&1);
728   }
729   while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
730   if( zNum<zEnd ){
731     if( *zNum=='-' ){
732       neg = 1;
733       zNum+=incr;
734     }else if( *zNum=='+' ){
735       zNum+=incr;
736     }
737   }
738   zStart = zNum;
739   while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
740   for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
741     u = u*10 + c - '0';
742   }
743   testcase( i==18*incr );
744   testcase( i==19*incr );
745   testcase( i==20*incr );
746   if( u>LARGEST_INT64 ){
747     /* This test and assignment is needed only to suppress UB warnings
748     ** from clang and -fsanitize=undefined.  This test and assignment make
749     ** the code a little larger and slower, and no harm comes from omitting
750     ** them, but we must appaise the undefined-behavior pharisees. */
751     *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
752   }else if( neg ){
753     *pNum = -(i64)u;
754   }else{
755     *pNum = (i64)u;
756   }
757   rc = 0;
758   if( i==0 && zStart==zNum ){    /* No digits */
759     rc = -1;
760   }else if( nonNum ){            /* UTF16 with high-order bytes non-zero */
761     rc = 1;
762   }else if( &zNum[i]<zEnd ){     /* Extra bytes at the end */
763     int jj = i;
764     do{
765       if( !sqlite3Isspace(zNum[jj]) ){
766         rc = 1;          /* Extra non-space text after the integer */
767         break;
768       }
769       jj += incr;
770     }while( &zNum[jj]<zEnd );
771   }
772   if( i<19*incr ){
773     /* Less than 19 digits, so we know that it fits in 64 bits */
774     assert( u<=LARGEST_INT64 );
775     return rc;
776   }else{
777     /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
778     c = i>19*incr ? 1 : compare2pow63(zNum, incr);
779     if( c<0 ){
780       /* zNum is less than 9223372036854775808 so it fits */
781       assert( u<=LARGEST_INT64 );
782       return rc;
783     }else{
784       *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
785       if( c>0 ){
786         /* zNum is greater than 9223372036854775808 so it overflows */
787         return 2;
788       }else{
789         /* zNum is exactly 9223372036854775808.  Fits if negative.  The
790         ** special case 2 overflow if positive */
791         assert( u-1==LARGEST_INT64 );
792         return neg ? rc : 3;
793       }
794     }
795   }
796 }
797 
798 /*
799 ** Transform a UTF-8 integer literal, in either decimal or hexadecimal,
800 ** into a 64-bit signed integer.  This routine accepts hexadecimal literals,
801 ** whereas sqlite3Atoi64() does not.
802 **
803 ** Returns:
804 **
805 **     0    Successful transformation.  Fits in a 64-bit signed integer.
806 **     1    Excess text after the integer value
807 **     2    Integer too large for a 64-bit signed integer or is malformed
808 **     3    Special case of 9223372036854775808
809 */
810 int sqlite3DecOrHexToI64(const char *z, i64 *pOut){
811 #ifndef SQLITE_OMIT_HEX_INTEGER
812   if( z[0]=='0'
813    && (z[1]=='x' || z[1]=='X')
814   ){
815     u64 u = 0;
816     int i, k;
817     for(i=2; z[i]=='0'; i++){}
818     for(k=i; sqlite3Isxdigit(z[k]); k++){
819       u = u*16 + sqlite3HexToInt(z[k]);
820     }
821     memcpy(pOut, &u, 8);
822     return (z[k]==0 && k-i<=16) ? 0 : 2;
823   }else
824 #endif /* SQLITE_OMIT_HEX_INTEGER */
825   {
826     return sqlite3Atoi64(z, pOut, sqlite3Strlen30(z), SQLITE_UTF8);
827   }
828 }
829 
830 /*
831 ** If zNum represents an integer that will fit in 32-bits, then set
832 ** *pValue to that integer and return true.  Otherwise return false.
833 **
834 ** This routine accepts both decimal and hexadecimal notation for integers.
835 **
836 ** Any non-numeric characters that following zNum are ignored.
837 ** This is different from sqlite3Atoi64() which requires the
838 ** input number to be zero-terminated.
839 */
840 int sqlite3GetInt32(const char *zNum, int *pValue){
841   sqlite_int64 v = 0;
842   int i, c;
843   int neg = 0;
844   if( zNum[0]=='-' ){
845     neg = 1;
846     zNum++;
847   }else if( zNum[0]=='+' ){
848     zNum++;
849   }
850 #ifndef SQLITE_OMIT_HEX_INTEGER
851   else if( zNum[0]=='0'
852         && (zNum[1]=='x' || zNum[1]=='X')
853         && sqlite3Isxdigit(zNum[2])
854   ){
855     u32 u = 0;
856     zNum += 2;
857     while( zNum[0]=='0' ) zNum++;
858     for(i=0; sqlite3Isxdigit(zNum[i]) && i<8; i++){
859       u = u*16 + sqlite3HexToInt(zNum[i]);
860     }
861     if( (u&0x80000000)==0 && sqlite3Isxdigit(zNum[i])==0 ){
862       memcpy(pValue, &u, 4);
863       return 1;
864     }else{
865       return 0;
866     }
867   }
868 #endif
869   if( !sqlite3Isdigit(zNum[0]) ) return 0;
870   while( zNum[0]=='0' ) zNum++;
871   for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
872     v = v*10 + c;
873   }
874 
875   /* The longest decimal representation of a 32 bit integer is 10 digits:
876   **
877   **             1234567890
878   **     2^31 -> 2147483648
879   */
880   testcase( i==10 );
881   if( i>10 ){
882     return 0;
883   }
884   testcase( v-neg==2147483647 );
885   if( v-neg>2147483647 ){
886     return 0;
887   }
888   if( neg ){
889     v = -v;
890   }
891   *pValue = (int)v;
892   return 1;
893 }
894 
895 /*
896 ** Return a 32-bit integer value extracted from a string.  If the
897 ** string is not an integer, just return 0.
898 */
899 int sqlite3Atoi(const char *z){
900   int x = 0;
901   sqlite3GetInt32(z, &x);
902   return x;
903 }
904 
905 /*
906 ** Try to convert z into an unsigned 32-bit integer.  Return true on
907 ** success and false if there is an error.
908 **
909 ** Only decimal notation is accepted.
910 */
911 int sqlite3GetUInt32(const char *z, u32 *pI){
912   u64 v = 0;
913   int i;
914   for(i=0; sqlite3Isdigit(z[i]); i++){
915     v = v*10 + z[i] - '0';
916     if( v>4294967296LL ){ *pI = 0; return 0; }
917   }
918   if( i==0 || z[i]!=0 ){ *pI = 0; return 0; }
919   *pI = (u32)v;
920   return 1;
921 }
922 
923 /*
924 ** The variable-length integer encoding is as follows:
925 **
926 ** KEY:
927 **         A = 0xxxxxxx    7 bits of data and one flag bit
928 **         B = 1xxxxxxx    7 bits of data and one flag bit
929 **         C = xxxxxxxx    8 bits of data
930 **
931 **  7 bits - A
932 ** 14 bits - BA
933 ** 21 bits - BBA
934 ** 28 bits - BBBA
935 ** 35 bits - BBBBA
936 ** 42 bits - BBBBBA
937 ** 49 bits - BBBBBBA
938 ** 56 bits - BBBBBBBA
939 ** 64 bits - BBBBBBBBC
940 */
941 
942 /*
943 ** Write a 64-bit variable-length integer to memory starting at p[0].
944 ** The length of data write will be between 1 and 9 bytes.  The number
945 ** of bytes written is returned.
946 **
947 ** A variable-length integer consists of the lower 7 bits of each byte
948 ** for all bytes that have the 8th bit set and one byte with the 8th
949 ** bit clear.  Except, if we get to the 9th byte, it stores the full
950 ** 8 bits and is the last byte.
951 */
952 static int SQLITE_NOINLINE putVarint64(unsigned char *p, u64 v){
953   int i, j, n;
954   u8 buf[10];
955   if( v & (((u64)0xff000000)<<32) ){
956     p[8] = (u8)v;
957     v >>= 8;
958     for(i=7; i>=0; i--){
959       p[i] = (u8)((v & 0x7f) | 0x80);
960       v >>= 7;
961     }
962     return 9;
963   }
964   n = 0;
965   do{
966     buf[n++] = (u8)((v & 0x7f) | 0x80);
967     v >>= 7;
968   }while( v!=0 );
969   buf[0] &= 0x7f;
970   assert( n<=9 );
971   for(i=0, j=n-1; j>=0; j--, i++){
972     p[i] = buf[j];
973   }
974   return n;
975 }
976 int sqlite3PutVarint(unsigned char *p, u64 v){
977   if( v<=0x7f ){
978     p[0] = v&0x7f;
979     return 1;
980   }
981   if( v<=0x3fff ){
982     p[0] = ((v>>7)&0x7f)|0x80;
983     p[1] = v&0x7f;
984     return 2;
985   }
986   return putVarint64(p,v);
987 }
988 
989 /*
990 ** Bitmasks used by sqlite3GetVarint().  These precomputed constants
991 ** are defined here rather than simply putting the constant expressions
992 ** inline in order to work around bugs in the RVT compiler.
993 **
994 ** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
995 **
996 ** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
997 */
998 #define SLOT_2_0     0x001fc07f
999 #define SLOT_4_2_0   0xf01fc07f
1000 
1001 
1002 /*
1003 ** Read a 64-bit variable-length integer from memory starting at p[0].
1004 ** Return the number of bytes read.  The value is stored in *v.
1005 */
1006 u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
1007   u32 a,b,s;
1008 
1009   if( ((signed char*)p)[0]>=0 ){
1010     *v = *p;
1011     return 1;
1012   }
1013   if( ((signed char*)p)[1]>=0 ){
1014     *v = ((u32)(p[0]&0x7f)<<7) | p[1];
1015     return 2;
1016   }
1017 
1018   /* Verify that constants are precomputed correctly */
1019   assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
1020   assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
1021 
1022   a = ((u32)p[0])<<14;
1023   b = p[1];
1024   p += 2;
1025   a |= *p;
1026   /* a: p0<<14 | p2 (unmasked) */
1027   if (!(a&0x80))
1028   {
1029     a &= SLOT_2_0;
1030     b &= 0x7f;
1031     b = b<<7;
1032     a |= b;
1033     *v = a;
1034     return 3;
1035   }
1036 
1037   /* CSE1 from below */
1038   a &= SLOT_2_0;
1039   p++;
1040   b = b<<14;
1041   b |= *p;
1042   /* b: p1<<14 | p3 (unmasked) */
1043   if (!(b&0x80))
1044   {
1045     b &= SLOT_2_0;
1046     /* moved CSE1 up */
1047     /* a &= (0x7f<<14)|(0x7f); */
1048     a = a<<7;
1049     a |= b;
1050     *v = a;
1051     return 4;
1052   }
1053 
1054   /* a: p0<<14 | p2 (masked) */
1055   /* b: p1<<14 | p3 (unmasked) */
1056   /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
1057   /* moved CSE1 up */
1058   /* a &= (0x7f<<14)|(0x7f); */
1059   b &= SLOT_2_0;
1060   s = a;
1061   /* s: p0<<14 | p2 (masked) */
1062 
1063   p++;
1064   a = a<<14;
1065   a |= *p;
1066   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
1067   if (!(a&0x80))
1068   {
1069     /* we can skip these cause they were (effectively) done above
1070     ** while calculating s */
1071     /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
1072     /* b &= (0x7f<<14)|(0x7f); */
1073     b = b<<7;
1074     a |= b;
1075     s = s>>18;
1076     *v = ((u64)s)<<32 | a;
1077     return 5;
1078   }
1079 
1080   /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
1081   s = s<<7;
1082   s |= b;
1083   /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
1084 
1085   p++;
1086   b = b<<14;
1087   b |= *p;
1088   /* b: p1<<28 | p3<<14 | p5 (unmasked) */
1089   if (!(b&0x80))
1090   {
1091     /* we can skip this cause it was (effectively) done above in calc'ing s */
1092     /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
1093     a &= SLOT_2_0;
1094     a = a<<7;
1095     a |= b;
1096     s = s>>18;
1097     *v = ((u64)s)<<32 | a;
1098     return 6;
1099   }
1100 
1101   p++;
1102   a = a<<14;
1103   a |= *p;
1104   /* a: p2<<28 | p4<<14 | p6 (unmasked) */
1105   if (!(a&0x80))
1106   {
1107     a &= SLOT_4_2_0;
1108     b &= SLOT_2_0;
1109     b = b<<7;
1110     a |= b;
1111     s = s>>11;
1112     *v = ((u64)s)<<32 | a;
1113     return 7;
1114   }
1115 
1116   /* CSE2 from below */
1117   a &= SLOT_2_0;
1118   p++;
1119   b = b<<14;
1120   b |= *p;
1121   /* b: p3<<28 | p5<<14 | p7 (unmasked) */
1122   if (!(b&0x80))
1123   {
1124     b &= SLOT_4_2_0;
1125     /* moved CSE2 up */
1126     /* a &= (0x7f<<14)|(0x7f); */
1127     a = a<<7;
1128     a |= b;
1129     s = s>>4;
1130     *v = ((u64)s)<<32 | a;
1131     return 8;
1132   }
1133 
1134   p++;
1135   a = a<<15;
1136   a |= *p;
1137   /* a: p4<<29 | p6<<15 | p8 (unmasked) */
1138 
1139   /* moved CSE2 up */
1140   /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
1141   b &= SLOT_2_0;
1142   b = b<<8;
1143   a |= b;
1144 
1145   s = s<<4;
1146   b = p[-4];
1147   b &= 0x7f;
1148   b = b>>3;
1149   s |= b;
1150 
1151   *v = ((u64)s)<<32 | a;
1152 
1153   return 9;
1154 }
1155 
1156 /*
1157 ** Read a 32-bit variable-length integer from memory starting at p[0].
1158 ** Return the number of bytes read.  The value is stored in *v.
1159 **
1160 ** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
1161 ** integer, then set *v to 0xffffffff.
1162 **
1163 ** A MACRO version, getVarint32, is provided which inlines the
1164 ** single-byte case.  All code should use the MACRO version as
1165 ** this function assumes the single-byte case has already been handled.
1166 */
1167 u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
1168   u32 a,b;
1169 
1170   /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
1171   ** by the getVarin32() macro */
1172   a = *p;
1173   /* a: p0 (unmasked) */
1174 #ifndef getVarint32
1175   if (!(a&0x80))
1176   {
1177     /* Values between 0 and 127 */
1178     *v = a;
1179     return 1;
1180   }
1181 #endif
1182 
1183   /* The 2-byte case */
1184   p++;
1185   b = *p;
1186   /* b: p1 (unmasked) */
1187   if (!(b&0x80))
1188   {
1189     /* Values between 128 and 16383 */
1190     a &= 0x7f;
1191     a = a<<7;
1192     *v = a | b;
1193     return 2;
1194   }
1195 
1196   /* The 3-byte case */
1197   p++;
1198   a = a<<14;
1199   a |= *p;
1200   /* a: p0<<14 | p2 (unmasked) */
1201   if (!(a&0x80))
1202   {
1203     /* Values between 16384 and 2097151 */
1204     a &= (0x7f<<14)|(0x7f);
1205     b &= 0x7f;
1206     b = b<<7;
1207     *v = a | b;
1208     return 3;
1209   }
1210 
1211   /* A 32-bit varint is used to store size information in btrees.
1212   ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
1213   ** A 3-byte varint is sufficient, for example, to record the size
1214   ** of a 1048569-byte BLOB or string.
1215   **
1216   ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
1217   ** rare larger cases can be handled by the slower 64-bit varint
1218   ** routine.
1219   */
1220 #if 1
1221   {
1222     u64 v64;
1223     u8 n;
1224 
1225     n = sqlite3GetVarint(p-2, &v64);
1226     assert( n>3 && n<=9 );
1227     if( (v64 & SQLITE_MAX_U32)!=v64 ){
1228       *v = 0xffffffff;
1229     }else{
1230       *v = (u32)v64;
1231     }
1232     return n;
1233   }
1234 
1235 #else
1236   /* For following code (kept for historical record only) shows an
1237   ** unrolling for the 3- and 4-byte varint cases.  This code is
1238   ** slightly faster, but it is also larger and much harder to test.
1239   */
1240   p++;
1241   b = b<<14;
1242   b |= *p;
1243   /* b: p1<<14 | p3 (unmasked) */
1244   if (!(b&0x80))
1245   {
1246     /* Values between 2097152 and 268435455 */
1247     b &= (0x7f<<14)|(0x7f);
1248     a &= (0x7f<<14)|(0x7f);
1249     a = a<<7;
1250     *v = a | b;
1251     return 4;
1252   }
1253 
1254   p++;
1255   a = a<<14;
1256   a |= *p;
1257   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
1258   if (!(a&0x80))
1259   {
1260     /* Values  between 268435456 and 34359738367 */
1261     a &= SLOT_4_2_0;
1262     b &= SLOT_4_2_0;
1263     b = b<<7;
1264     *v = a | b;
1265     return 5;
1266   }
1267 
1268   /* We can only reach this point when reading a corrupt database
1269   ** file.  In that case we are not in any hurry.  Use the (relatively
1270   ** slow) general-purpose sqlite3GetVarint() routine to extract the
1271   ** value. */
1272   {
1273     u64 v64;
1274     u8 n;
1275 
1276     p -= 4;
1277     n = sqlite3GetVarint(p, &v64);
1278     assert( n>5 && n<=9 );
1279     *v = (u32)v64;
1280     return n;
1281   }
1282 #endif
1283 }
1284 
1285 /*
1286 ** Return the number of bytes that will be needed to store the given
1287 ** 64-bit integer.
1288 */
1289 int sqlite3VarintLen(u64 v){
1290   int i;
1291   for(i=1; (v >>= 7)!=0; i++){ assert( i<10 ); }
1292   return i;
1293 }
1294 
1295 
1296 /*
1297 ** Read or write a four-byte big-endian integer value.
1298 */
1299 u32 sqlite3Get4byte(const u8 *p){
1300 #if SQLITE_BYTEORDER==4321
1301   u32 x;
1302   memcpy(&x,p,4);
1303   return x;
1304 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1305   u32 x;
1306   memcpy(&x,p,4);
1307   return __builtin_bswap32(x);
1308 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1309   u32 x;
1310   memcpy(&x,p,4);
1311   return _byteswap_ulong(x);
1312 #else
1313   testcase( p[0]&0x80 );
1314   return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
1315 #endif
1316 }
1317 void sqlite3Put4byte(unsigned char *p, u32 v){
1318 #if SQLITE_BYTEORDER==4321
1319   memcpy(p,&v,4);
1320 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1321   u32 x = __builtin_bswap32(v);
1322   memcpy(p,&x,4);
1323 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1324   u32 x = _byteswap_ulong(v);
1325   memcpy(p,&x,4);
1326 #else
1327   p[0] = (u8)(v>>24);
1328   p[1] = (u8)(v>>16);
1329   p[2] = (u8)(v>>8);
1330   p[3] = (u8)v;
1331 #endif
1332 }
1333 
1334 
1335 
1336 /*
1337 ** Translate a single byte of Hex into an integer.
1338 ** This routine only works if h really is a valid hexadecimal
1339 ** character:  0..9a..fA..F
1340 */
1341 u8 sqlite3HexToInt(int h){
1342   assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
1343 #ifdef SQLITE_ASCII
1344   h += 9*(1&(h>>6));
1345 #endif
1346 #ifdef SQLITE_EBCDIC
1347   h += 9*(1&~(h>>4));
1348 #endif
1349   return (u8)(h & 0xf);
1350 }
1351 
1352 #if !defined(SQLITE_OMIT_BLOB_LITERAL)
1353 /*
1354 ** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
1355 ** value.  Return a pointer to its binary value.  Space to hold the
1356 ** binary value has been obtained from malloc and must be freed by
1357 ** the calling routine.
1358 */
1359 void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
1360   char *zBlob;
1361   int i;
1362 
1363   zBlob = (char *)sqlite3DbMallocRawNN(db, n/2 + 1);
1364   n--;
1365   if( zBlob ){
1366     for(i=0; i<n; i+=2){
1367       zBlob[i/2] = (sqlite3HexToInt(z[i])<<4) | sqlite3HexToInt(z[i+1]);
1368     }
1369     zBlob[i/2] = 0;
1370   }
1371   return zBlob;
1372 }
1373 #endif /* !SQLITE_OMIT_BLOB_LITERAL */
1374 
1375 /*
1376 ** Log an error that is an API call on a connection pointer that should
1377 ** not have been used.  The "type" of connection pointer is given as the
1378 ** argument.  The zType is a word like "NULL" or "closed" or "invalid".
1379 */
1380 static void logBadConnection(const char *zType){
1381   sqlite3_log(SQLITE_MISUSE,
1382      "API call with %s database connection pointer",
1383      zType
1384   );
1385 }
1386 
1387 /*
1388 ** Check to make sure we have a valid db pointer.  This test is not
1389 ** foolproof but it does provide some measure of protection against
1390 ** misuse of the interface such as passing in db pointers that are
1391 ** NULL or which have been previously closed.  If this routine returns
1392 ** 1 it means that the db pointer is valid and 0 if it should not be
1393 ** dereferenced for any reason.  The calling function should invoke
1394 ** SQLITE_MISUSE immediately.
1395 **
1396 ** sqlite3SafetyCheckOk() requires that the db pointer be valid for
1397 ** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
1398 ** open properly and is not fit for general use but which can be
1399 ** used as an argument to sqlite3_errmsg() or sqlite3_close().
1400 */
1401 int sqlite3SafetyCheckOk(sqlite3 *db){
1402   u32 magic;
1403   if( db==0 ){
1404     logBadConnection("NULL");
1405     return 0;
1406   }
1407   magic = db->magic;
1408   if( magic!=SQLITE_MAGIC_OPEN ){
1409     if( sqlite3SafetyCheckSickOrOk(db) ){
1410       testcase( sqlite3GlobalConfig.xLog!=0 );
1411       logBadConnection("unopened");
1412     }
1413     return 0;
1414   }else{
1415     return 1;
1416   }
1417 }
1418 int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
1419   u32 magic;
1420   magic = db->magic;
1421   if( magic!=SQLITE_MAGIC_SICK &&
1422       magic!=SQLITE_MAGIC_OPEN &&
1423       magic!=SQLITE_MAGIC_BUSY ){
1424     testcase( sqlite3GlobalConfig.xLog!=0 );
1425     logBadConnection("invalid");
1426     return 0;
1427   }else{
1428     return 1;
1429   }
1430 }
1431 
1432 /*
1433 ** Attempt to add, substract, or multiply the 64-bit signed value iB against
1434 ** the other 64-bit signed integer at *pA and store the result in *pA.
1435 ** Return 0 on success.  Or if the operation would have resulted in an
1436 ** overflow, leave *pA unchanged and return 1.
1437 */
1438 int sqlite3AddInt64(i64 *pA, i64 iB){
1439 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1440   return __builtin_add_overflow(*pA, iB, pA);
1441 #else
1442   i64 iA = *pA;
1443   testcase( iA==0 ); testcase( iA==1 );
1444   testcase( iB==-1 ); testcase( iB==0 );
1445   if( iB>=0 ){
1446     testcase( iA>0 && LARGEST_INT64 - iA == iB );
1447     testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
1448     if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
1449   }else{
1450     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
1451     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
1452     if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
1453   }
1454   *pA += iB;
1455   return 0;
1456 #endif
1457 }
1458 int sqlite3SubInt64(i64 *pA, i64 iB){
1459 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1460   return __builtin_sub_overflow(*pA, iB, pA);
1461 #else
1462   testcase( iB==SMALLEST_INT64+1 );
1463   if( iB==SMALLEST_INT64 ){
1464     testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
1465     if( (*pA)>=0 ) return 1;
1466     *pA -= iB;
1467     return 0;
1468   }else{
1469     return sqlite3AddInt64(pA, -iB);
1470   }
1471 #endif
1472 }
1473 int sqlite3MulInt64(i64 *pA, i64 iB){
1474 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1475   return __builtin_mul_overflow(*pA, iB, pA);
1476 #else
1477   i64 iA = *pA;
1478   if( iB>0 ){
1479     if( iA>LARGEST_INT64/iB ) return 1;
1480     if( iA<SMALLEST_INT64/iB ) return 1;
1481   }else if( iB<0 ){
1482     if( iA>0 ){
1483       if( iB<SMALLEST_INT64/iA ) return 1;
1484     }else if( iA<0 ){
1485       if( iB==SMALLEST_INT64 ) return 1;
1486       if( iA==SMALLEST_INT64 ) return 1;
1487       if( -iA>LARGEST_INT64/-iB ) return 1;
1488     }
1489   }
1490   *pA = iA*iB;
1491   return 0;
1492 #endif
1493 }
1494 
1495 /*
1496 ** Compute the absolute value of a 32-bit signed integer, of possible.  Or
1497 ** if the integer has a value of -2147483648, return +2147483647
1498 */
1499 int sqlite3AbsInt32(int x){
1500   if( x>=0 ) return x;
1501   if( x==(int)0x80000000 ) return 0x7fffffff;
1502   return -x;
1503 }
1504 
1505 #ifdef SQLITE_ENABLE_8_3_NAMES
1506 /*
1507 ** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
1508 ** filename in zBaseFilename is a URI with the "8_3_names=1" parameter and
1509 ** if filename in z[] has a suffix (a.k.a. "extension") that is longer than
1510 ** three characters, then shorten the suffix on z[] to be the last three
1511 ** characters of the original suffix.
1512 **
1513 ** If SQLITE_ENABLE_8_3_NAMES is set to 2 at compile-time, then always
1514 ** do the suffix shortening regardless of URI parameter.
1515 **
1516 ** Examples:
1517 **
1518 **     test.db-journal    =>   test.nal
1519 **     test.db-wal        =>   test.wal
1520 **     test.db-shm        =>   test.shm
1521 **     test.db-mj7f3319fa =>   test.9fa
1522 */
1523 void sqlite3FileSuffix3(const char *zBaseFilename, char *z){
1524 #if SQLITE_ENABLE_8_3_NAMES<2
1525   if( sqlite3_uri_boolean(zBaseFilename, "8_3_names", 0) )
1526 #endif
1527   {
1528     int i, sz;
1529     sz = sqlite3Strlen30(z);
1530     for(i=sz-1; i>0 && z[i]!='/' && z[i]!='.'; i--){}
1531     if( z[i]=='.' && ALWAYS(sz>i+4) ) memmove(&z[i+1], &z[sz-3], 4);
1532   }
1533 }
1534 #endif
1535 
1536 /*
1537 ** Find (an approximate) sum of two LogEst values.  This computation is
1538 ** not a simple "+" operator because LogEst is stored as a logarithmic
1539 ** value.
1540 **
1541 */
1542 LogEst sqlite3LogEstAdd(LogEst a, LogEst b){
1543   static const unsigned char x[] = {
1544      10, 10,                         /* 0,1 */
1545       9, 9,                          /* 2,3 */
1546       8, 8,                          /* 4,5 */
1547       7, 7, 7,                       /* 6,7,8 */
1548       6, 6, 6,                       /* 9,10,11 */
1549       5, 5, 5,                       /* 12-14 */
1550       4, 4, 4, 4,                    /* 15-18 */
1551       3, 3, 3, 3, 3, 3,              /* 19-24 */
1552       2, 2, 2, 2, 2, 2, 2,           /* 25-31 */
1553   };
1554   if( a>=b ){
1555     if( a>b+49 ) return a;
1556     if( a>b+31 ) return a+1;
1557     return a+x[a-b];
1558   }else{
1559     if( b>a+49 ) return b;
1560     if( b>a+31 ) return b+1;
1561     return b+x[b-a];
1562   }
1563 }
1564 
1565 /*
1566 ** Convert an integer into a LogEst.  In other words, compute an
1567 ** approximation for 10*log2(x).
1568 */
1569 LogEst sqlite3LogEst(u64 x){
1570   static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 };
1571   LogEst y = 40;
1572   if( x<8 ){
1573     if( x<2 ) return 0;
1574     while( x<8 ){  y -= 10; x <<= 1; }
1575   }else{
1576 #if GCC_VERSION>=5004000
1577     int i = 60 - __builtin_clzll(x);
1578     y += i*10;
1579     x >>= i;
1580 #else
1581     while( x>255 ){ y += 40; x >>= 4; }  /*OPTIMIZATION-IF-TRUE*/
1582     while( x>15 ){  y += 10; x >>= 1; }
1583 #endif
1584   }
1585   return a[x&7] + y - 10;
1586 }
1587 
1588 #ifndef SQLITE_OMIT_VIRTUALTABLE
1589 /*
1590 ** Convert a double into a LogEst
1591 ** In other words, compute an approximation for 10*log2(x).
1592 */
1593 LogEst sqlite3LogEstFromDouble(double x){
1594   u64 a;
1595   LogEst e;
1596   assert( sizeof(x)==8 && sizeof(a)==8 );
1597   if( x<=1 ) return 0;
1598   if( x<=2000000000 ) return sqlite3LogEst((u64)x);
1599   memcpy(&a, &x, 8);
1600   e = (a>>52) - 1022;
1601   return e*10;
1602 }
1603 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1604 
1605 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1606     defined(SQLITE_ENABLE_STAT4) || \
1607     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1608 /*
1609 ** Convert a LogEst into an integer.
1610 **
1611 ** Note that this routine is only used when one or more of various
1612 ** non-standard compile-time options is enabled.
1613 */
1614 u64 sqlite3LogEstToInt(LogEst x){
1615   u64 n;
1616   n = x%10;
1617   x /= 10;
1618   if( n>=5 ) n -= 2;
1619   else if( n>=1 ) n -= 1;
1620 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1621     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1622   if( x>60 ) return (u64)LARGEST_INT64;
1623 #else
1624   /* If only SQLITE_ENABLE_STAT4 is on, then the largest input
1625   ** possible to this routine is 310, resulting in a maximum x of 31 */
1626   assert( x<=60 );
1627 #endif
1628   return x>=3 ? (n+8)<<(x-3) : (n+8)>>(3-x);
1629 }
1630 #endif /* defined SCANSTAT or STAT4 or ESTIMATED_ROWS */
1631 
1632 /*
1633 ** Add a new name/number pair to a VList.  This might require that the
1634 ** VList object be reallocated, so return the new VList.  If an OOM
1635 ** error occurs, the original VList returned and the
1636 ** db->mallocFailed flag is set.
1637 **
1638 ** A VList is really just an array of integers.  To destroy a VList,
1639 ** simply pass it to sqlite3DbFree().
1640 **
1641 ** The first integer is the number of integers allocated for the whole
1642 ** VList.  The second integer is the number of integers actually used.
1643 ** Each name/number pair is encoded by subsequent groups of 3 or more
1644 ** integers.
1645 **
1646 ** Each name/number pair starts with two integers which are the numeric
1647 ** value for the pair and the size of the name/number pair, respectively.
1648 ** The text name overlays one or more following integers.  The text name
1649 ** is always zero-terminated.
1650 **
1651 ** Conceptually:
1652 **
1653 **    struct VList {
1654 **      int nAlloc;   // Number of allocated slots
1655 **      int nUsed;    // Number of used slots
1656 **      struct VListEntry {
1657 **        int iValue;    // Value for this entry
1658 **        int nSlot;     // Slots used by this entry
1659 **        // ... variable name goes here
1660 **      } a[0];
1661 **    }
1662 **
1663 ** During code generation, pointers to the variable names within the
1664 ** VList are taken.  When that happens, nAlloc is set to zero as an
1665 ** indication that the VList may never again be enlarged, since the
1666 ** accompanying realloc() would invalidate the pointers.
1667 */
1668 VList *sqlite3VListAdd(
1669   sqlite3 *db,           /* The database connection used for malloc() */
1670   VList *pIn,            /* The input VList.  Might be NULL */
1671   const char *zName,     /* Name of symbol to add */
1672   int nName,             /* Bytes of text in zName */
1673   int iVal               /* Value to associate with zName */
1674 ){
1675   int nInt;              /* number of sizeof(int) objects needed for zName */
1676   char *z;               /* Pointer to where zName will be stored */
1677   int i;                 /* Index in pIn[] where zName is stored */
1678 
1679   nInt = nName/4 + 3;
1680   assert( pIn==0 || pIn[0]>=3 );  /* Verify ok to add new elements */
1681   if( pIn==0 || pIn[1]+nInt > pIn[0] ){
1682     /* Enlarge the allocation */
1683     sqlite3_int64 nAlloc = (pIn ? 2*(sqlite3_int64)pIn[0] : 10) + nInt;
1684     VList *pOut = sqlite3DbRealloc(db, pIn, nAlloc*sizeof(int));
1685     if( pOut==0 ) return pIn;
1686     if( pIn==0 ) pOut[1] = 2;
1687     pIn = pOut;
1688     pIn[0] = nAlloc;
1689   }
1690   i = pIn[1];
1691   pIn[i] = iVal;
1692   pIn[i+1] = nInt;
1693   z = (char*)&pIn[i+2];
1694   pIn[1] = i+nInt;
1695   assert( pIn[1]<=pIn[0] );
1696   memcpy(z, zName, nName);
1697   z[nName] = 0;
1698   return pIn;
1699 }
1700 
1701 /*
1702 ** Return a pointer to the name of a variable in the given VList that
1703 ** has the value iVal.  Or return a NULL if there is no such variable in
1704 ** the list
1705 */
1706 const char *sqlite3VListNumToName(VList *pIn, int iVal){
1707   int i, mx;
1708   if( pIn==0 ) return 0;
1709   mx = pIn[1];
1710   i = 2;
1711   do{
1712     if( pIn[i]==iVal ) return (char*)&pIn[i+2];
1713     i += pIn[i+1];
1714   }while( i<mx );
1715   return 0;
1716 }
1717 
1718 /*
1719 ** Return the number of the variable named zName, if it is in VList.
1720 ** or return 0 if there is no such variable.
1721 */
1722 int sqlite3VListNameToNum(VList *pIn, const char *zName, int nName){
1723   int i, mx;
1724   if( pIn==0 ) return 0;
1725   mx = pIn[1];
1726   i = 2;
1727   do{
1728     const char *z = (const char*)&pIn[i+2];
1729     if( strncmp(z,zName,nName)==0 && z[nName]==0 ) return pIn[i];
1730     i += pIn[i+1];
1731   }while( i<mx );
1732   return 0;
1733 }
1734