xref: /sqlite-3.40.0/src/util.c (revision cbf1c8c2)
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)==0 ) return zDflt;
93   return pCol->zName + strlen(pCol->zName) + 1;
94 }
95 
96 /*
97 ** Helper function for sqlite3Error() - called rarely.  Broken out into
98 ** a separate routine to avoid unnecessary register saves on entry to
99 ** sqlite3Error().
100 */
101 static SQLITE_NOINLINE void  sqlite3ErrorFinish(sqlite3 *db, int err_code){
102   if( db->pErr ) sqlite3ValueSetNull(db->pErr);
103   sqlite3SystemError(db, err_code);
104 }
105 
106 /*
107 ** Set the current error code to err_code and clear any prior error message.
108 ** Also set iSysErrno (by calling sqlite3System) if the err_code indicates
109 ** that would be appropriate.
110 */
111 void sqlite3Error(sqlite3 *db, int err_code){
112   assert( db!=0 );
113   db->errCode = err_code;
114   if( err_code || db->pErr ) sqlite3ErrorFinish(db, err_code);
115 }
116 
117 /*
118 ** Load the sqlite3.iSysErrno field if that is an appropriate thing
119 ** to do based on the SQLite error code in rc.
120 */
121 void sqlite3SystemError(sqlite3 *db, int rc){
122   if( rc==SQLITE_IOERR_NOMEM ) return;
123   rc &= 0xff;
124   if( rc==SQLITE_CANTOPEN || rc==SQLITE_IOERR ){
125     db->iSysErrno = sqlite3OsGetLastError(db->pVfs);
126   }
127 }
128 
129 /*
130 ** Set the most recent error code and error string for the sqlite
131 ** handle "db". The error code is set to "err_code".
132 **
133 ** If it is not NULL, string zFormat specifies the format of the
134 ** error string in the style of the printf functions: The following
135 ** format characters are allowed:
136 **
137 **      %s      Insert a string
138 **      %z      A string that should be freed after use
139 **      %d      Insert an integer
140 **      %T      Insert a token
141 **      %S      Insert the first element of a SrcList
142 **
143 ** zFormat and any string tokens that follow it are assumed to be
144 ** encoded in UTF-8.
145 **
146 ** To clear the most recent error for sqlite handle "db", sqlite3Error
147 ** should be called with err_code set to SQLITE_OK and zFormat set
148 ** to NULL.
149 */
150 void sqlite3ErrorWithMsg(sqlite3 *db, int err_code, const char *zFormat, ...){
151   assert( db!=0 );
152   db->errCode = err_code;
153   sqlite3SystemError(db, err_code);
154   if( zFormat==0 ){
155     sqlite3Error(db, err_code);
156   }else if( db->pErr || (db->pErr = sqlite3ValueNew(db))!=0 ){
157     char *z;
158     va_list ap;
159     va_start(ap, zFormat);
160     z = sqlite3VMPrintf(db, zFormat, ap);
161     va_end(ap);
162     sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
163   }
164 }
165 
166 /*
167 ** Add an error message to pParse->zErrMsg and increment pParse->nErr.
168 ** The following formatting characters are allowed:
169 **
170 **      %s      Insert a string
171 **      %z      A string that should be freed after use
172 **      %d      Insert an integer
173 **      %T      Insert a token
174 **      %S      Insert the first element of a SrcList
175 **
176 ** This function should be used to report any error that occurs while
177 ** compiling an SQL statement (i.e. within sqlite3_prepare()). The
178 ** last thing the sqlite3_prepare() function does is copy the error
179 ** stored by this function into the database handle using sqlite3Error().
180 ** Functions sqlite3Error() or sqlite3ErrorWithMsg() should be used
181 ** during statement execution (sqlite3_step() etc.).
182 */
183 void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
184   char *zMsg;
185   va_list ap;
186   sqlite3 *db = pParse->db;
187   va_start(ap, zFormat);
188   zMsg = sqlite3VMPrintf(db, zFormat, ap);
189   va_end(ap);
190   if( db->suppressErr ){
191     sqlite3DbFree(db, zMsg);
192   }else{
193     pParse->nErr++;
194     sqlite3DbFree(db, pParse->zErrMsg);
195     pParse->zErrMsg = zMsg;
196     pParse->rc = SQLITE_ERROR;
197     pParse->pWith = 0;
198   }
199 }
200 
201 /*
202 ** If database connection db is currently parsing SQL, then transfer
203 ** error code errCode to that parser if the parser has not already
204 ** encountered some other kind of error.
205 */
206 int sqlite3ErrorToParser(sqlite3 *db, int errCode){
207   Parse *pParse;
208   if( db==0 || (pParse = db->pParse)==0 ) return errCode;
209   pParse->rc = errCode;
210   pParse->nErr++;
211   return errCode;
212 }
213 
214 /*
215 ** Convert an SQL-style quoted string into a normal string by removing
216 ** the quote characters.  The conversion is done in-place.  If the
217 ** input does not begin with a quote character, then this routine
218 ** is a no-op.
219 **
220 ** The input string must be zero-terminated.  A new zero-terminator
221 ** is added to the dequoted string.
222 **
223 ** The return value is -1 if no dequoting occurs or the length of the
224 ** dequoted string, exclusive of the zero terminator, if dequoting does
225 ** occur.
226 **
227 ** 2002-02-14: This routine is extended to remove MS-Access style
228 ** brackets from around identifiers.  For example:  "[a-b-c]" becomes
229 ** "a-b-c".
230 */
231 void sqlite3Dequote(char *z){
232   char quote;
233   int i, j;
234   if( z==0 ) return;
235   quote = z[0];
236   if( !sqlite3Isquote(quote) ) return;
237   if( quote=='[' ) quote = ']';
238   for(i=1, j=0;; i++){
239     assert( z[i] );
240     if( z[i]==quote ){
241       if( z[i+1]==quote ){
242         z[j++] = quote;
243         i++;
244       }else{
245         break;
246       }
247     }else{
248       z[j++] = z[i];
249     }
250   }
251   z[j] = 0;
252 }
253 void sqlite3DequoteExpr(Expr *p){
254   assert( sqlite3Isquote(p->u.zToken[0]) );
255   p->flags |= p->u.zToken[0]=='"' ? EP_Quoted|EP_DblQuoted : EP_Quoted;
256   sqlite3Dequote(p->u.zToken);
257 }
258 
259 /*
260 ** Generate a Token object from a string
261 */
262 void sqlite3TokenInit(Token *p, char *z){
263   p->z = z;
264   p->n = sqlite3Strlen30(z);
265 }
266 
267 /* Convenient short-hand */
268 #define UpperToLower sqlite3UpperToLower
269 
270 /*
271 ** Some systems have stricmp().  Others have strcasecmp().  Because
272 ** there is no consistency, we will define our own.
273 **
274 ** IMPLEMENTATION-OF: R-30243-02494 The sqlite3_stricmp() and
275 ** sqlite3_strnicmp() APIs allow applications and extensions to compare
276 ** the contents of two buffers containing UTF-8 strings in a
277 ** case-independent fashion, using the same definition of "case
278 ** independence" that SQLite uses internally when comparing identifiers.
279 */
280 int sqlite3_stricmp(const char *zLeft, const char *zRight){
281   if( zLeft==0 ){
282     return zRight ? -1 : 0;
283   }else if( zRight==0 ){
284     return 1;
285   }
286   return sqlite3StrICmp(zLeft, zRight);
287 }
288 int sqlite3StrICmp(const char *zLeft, const char *zRight){
289   unsigned char *a, *b;
290   int c, x;
291   a = (unsigned char *)zLeft;
292   b = (unsigned char *)zRight;
293   for(;;){
294     c = *a;
295     x = *b;
296     if( c==x ){
297       if( c==0 ) break;
298     }else{
299       c = (int)UpperToLower[c] - (int)UpperToLower[x];
300       if( c ) break;
301     }
302     a++;
303     b++;
304   }
305   return c;
306 }
307 int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
308   register unsigned char *a, *b;
309   if( zLeft==0 ){
310     return zRight ? -1 : 0;
311   }else if( zRight==0 ){
312     return 1;
313   }
314   a = (unsigned char *)zLeft;
315   b = (unsigned char *)zRight;
316   while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
317   return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
318 }
319 
320 /*
321 ** Compute 10 to the E-th power.  Examples:  E==1 results in 10.
322 ** E==2 results in 100.  E==50 results in 1.0e50.
323 **
324 ** This routine only works for values of E between 1 and 341.
325 */
326 static LONGDOUBLE_TYPE sqlite3Pow10(int E){
327 #if defined(_MSC_VER)
328   static const LONGDOUBLE_TYPE x[] = {
329     1.0e+001L,
330     1.0e+002L,
331     1.0e+004L,
332     1.0e+008L,
333     1.0e+016L,
334     1.0e+032L,
335     1.0e+064L,
336     1.0e+128L,
337     1.0e+256L
338   };
339   LONGDOUBLE_TYPE r = 1.0;
340   int i;
341   assert( E>=0 && E<=307 );
342   for(i=0; E!=0; i++, E >>=1){
343     if( E & 1 ) r *= x[i];
344   }
345   return r;
346 #else
347   LONGDOUBLE_TYPE x = 10.0;
348   LONGDOUBLE_TYPE r = 1.0;
349   while(1){
350     if( E & 1 ) r *= x;
351     E >>= 1;
352     if( E==0 ) break;
353     x *= x;
354   }
355   return r;
356 #endif
357 }
358 
359 /*
360 ** The string z[] is an text representation of a real number.
361 ** Convert this string to a double and write it into *pResult.
362 **
363 ** The string z[] is length bytes in length (bytes, not characters) and
364 ** uses the encoding enc.  The string is not necessarily zero-terminated.
365 **
366 ** Return TRUE if the result is a valid real number (or integer) and FALSE
367 ** if the string is empty or contains extraneous text.  More specifically
368 ** return
369 **      1          =>  The input string is a pure integer
370 **      2 or more  =>  The input has a decimal point or eNNN clause
371 **      0 or less  =>  The input string is not a valid number
372 **     -1          =>  Not a valid number, but has a valid prefix which
373 **                     includes a decimal point and/or an eNNN clause
374 **
375 ** Valid numbers are in one of these formats:
376 **
377 **    [+-]digits[E[+-]digits]
378 **    [+-]digits.[digits][E[+-]digits]
379 **    [+-].digits[E[+-]digits]
380 **
381 ** Leading and trailing whitespace is ignored for the purpose of determining
382 ** validity.
383 **
384 ** If some prefix of the input string is a valid number, this routine
385 ** returns FALSE but it still converts the prefix and writes the result
386 ** into *pResult.
387 */
388 #if defined(_MSC_VER)
389 #pragma warning(disable : 4756)
390 #endif
391 int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
392 #ifndef SQLITE_OMIT_FLOATING_POINT
393   int incr;
394   const char *zEnd;
395   /* sign * significand * (10 ^ (esign * exponent)) */
396   int sign = 1;    /* sign of significand */
397   i64 s = 0;       /* significand */
398   int d = 0;       /* adjust exponent for shifting decimal point */
399   int esign = 1;   /* sign of exponent */
400   int e = 0;       /* exponent */
401   int eValid = 1;  /* True exponent is either not used or is well-formed */
402   double result;
403   int nDigit = 0;  /* Number of digits processed */
404   int eType = 1;   /* 1: pure integer,  2+: fractional  -1 or less: bad UTF16 */
405 
406   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
407   *pResult = 0.0;   /* Default return value, in case of an error */
408   if( length==0 ) return 0;
409 
410   if( enc==SQLITE_UTF8 ){
411     incr = 1;
412     zEnd = z + length;
413   }else{
414     int i;
415     incr = 2;
416     length &= ~1;
417     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
418     testcase( enc==SQLITE_UTF16LE );
419     testcase( enc==SQLITE_UTF16BE );
420     for(i=3-enc; i<length && z[i]==0; i+=2){}
421     if( i<length ) eType = -100;
422     zEnd = &z[i^1];
423     z += (enc&1);
424   }
425 
426   /* skip leading spaces */
427   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
428   if( z>=zEnd ) return 0;
429 
430   /* get sign of significand */
431   if( *z=='-' ){
432     sign = -1;
433     z+=incr;
434   }else if( *z=='+' ){
435     z+=incr;
436   }
437 
438   /* copy max significant digits to significand */
439   while( z<zEnd && sqlite3Isdigit(*z) ){
440     s = s*10 + (*z - '0');
441     z+=incr; nDigit++;
442     if( s>=((LARGEST_INT64-9)/10) ){
443       /* skip non-significant significand digits
444       ** (increase exponent by d to shift decimal left) */
445       while( z<zEnd && sqlite3Isdigit(*z) ){ z+=incr; d++; }
446     }
447   }
448   if( z>=zEnd ) goto do_atof_calc;
449 
450   /* if decimal point is present */
451   if( *z=='.' ){
452     z+=incr;
453     eType++;
454     /* copy digits from after decimal to significand
455     ** (decrease exponent by d to shift decimal right) */
456     while( z<zEnd && sqlite3Isdigit(*z) ){
457       if( s<((LARGEST_INT64-9)/10) ){
458         s = s*10 + (*z - '0');
459         d--;
460         nDigit++;
461       }
462       z+=incr;
463     }
464   }
465   if( z>=zEnd ) goto do_atof_calc;
466 
467   /* if exponent is present */
468   if( *z=='e' || *z=='E' ){
469     z+=incr;
470     eValid = 0;
471     eType++;
472 
473     /* This branch is needed to avoid a (harmless) buffer overread.  The
474     ** special comment alerts the mutation tester that the correct answer
475     ** is obtained even if the branch is omitted */
476     if( z>=zEnd ) goto do_atof_calc;              /*PREVENTS-HARMLESS-OVERREAD*/
477 
478     /* get sign of exponent */
479     if( *z=='-' ){
480       esign = -1;
481       z+=incr;
482     }else if( *z=='+' ){
483       z+=incr;
484     }
485     /* copy digits to exponent */
486     while( z<zEnd && sqlite3Isdigit(*z) ){
487       e = e<10000 ? (e*10 + (*z - '0')) : 10000;
488       z+=incr;
489       eValid = 1;
490     }
491   }
492 
493   /* skip trailing spaces */
494   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
495 
496 do_atof_calc:
497   /* adjust exponent by d, and update sign */
498   e = (e*esign) + d;
499   if( e<0 ) {
500     esign = -1;
501     e *= -1;
502   } else {
503     esign = 1;
504   }
505 
506   if( s==0 ) {
507     /* In the IEEE 754 standard, zero is signed. */
508     result = sign<0 ? -(double)0 : (double)0;
509   } else {
510     /* Attempt to reduce exponent.
511     **
512     ** Branches that are not required for the correct answer but which only
513     ** help to obtain the correct answer faster are marked with special
514     ** comments, as a hint to the mutation tester.
515     */
516     while( e>0 ){                                       /*OPTIMIZATION-IF-TRUE*/
517       if( esign>0 ){
518         if( s>=(LARGEST_INT64/10) ) break;             /*OPTIMIZATION-IF-FALSE*/
519         s *= 10;
520       }else{
521         if( s%10!=0 ) break;                           /*OPTIMIZATION-IF-FALSE*/
522         s /= 10;
523       }
524       e--;
525     }
526 
527     /* adjust the sign of significand */
528     s = sign<0 ? -s : s;
529 
530     if( e==0 ){                                         /*OPTIMIZATION-IF-TRUE*/
531       result = (double)s;
532     }else{
533       /* attempt to handle extremely small/large numbers better */
534       if( e>307 ){                                      /*OPTIMIZATION-IF-TRUE*/
535         if( e<342 ){                                    /*OPTIMIZATION-IF-TRUE*/
536           LONGDOUBLE_TYPE scale = sqlite3Pow10(e-308);
537           if( esign<0 ){
538             result = s / scale;
539             result /= 1.0e+308;
540           }else{
541             result = s * scale;
542             result *= 1.0e+308;
543           }
544         }else{ assert( e>=342 );
545           if( esign<0 ){
546             result = 0.0*s;
547           }else{
548 #ifdef INFINITY
549             result = INFINITY*s;
550 #else
551             result = 1e308*1e308*s;  /* Infinity */
552 #endif
553           }
554         }
555       }else{
556         LONGDOUBLE_TYPE scale = sqlite3Pow10(e);
557         if( esign<0 ){
558           result = s / scale;
559         }else{
560           result = s * scale;
561         }
562       }
563     }
564   }
565 
566   /* store the result */
567   *pResult = result;
568 
569   /* return true if number and no extra non-whitespace chracters after */
570   if( z==zEnd && nDigit>0 && eValid && eType>0 ){
571     return eType;
572   }else if( eType>=2 && (eType==3 || eValid) && nDigit>0 ){
573     return -1;
574   }else{
575     return 0;
576   }
577 #else
578   return !sqlite3Atoi64(z, pResult, length, enc);
579 #endif /* SQLITE_OMIT_FLOATING_POINT */
580 }
581 #if defined(_MSC_VER)
582 #pragma warning(default : 4756)
583 #endif
584 
585 /*
586 ** Compare the 19-character string zNum against the text representation
587 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive
588 ** if zNum is less than, equal to, or greater than the string.
589 ** Note that zNum must contain exactly 19 characters.
590 **
591 ** Unlike memcmp() this routine is guaranteed to return the difference
592 ** in the values of the last digit if the only difference is in the
593 ** last digit.  So, for example,
594 **
595 **      compare2pow63("9223372036854775800", 1)
596 **
597 ** will return -8.
598 */
599 static int compare2pow63(const char *zNum, int incr){
600   int c = 0;
601   int i;
602                     /* 012345678901234567 */
603   const char *pow63 = "922337203685477580";
604   for(i=0; c==0 && i<18; i++){
605     c = (zNum[i*incr]-pow63[i])*10;
606   }
607   if( c==0 ){
608     c = zNum[18*incr] - '8';
609     testcase( c==(-1) );
610     testcase( c==0 );
611     testcase( c==(+1) );
612   }
613   return c;
614 }
615 
616 /*
617 ** Convert zNum to a 64-bit signed integer.  zNum must be decimal. This
618 ** routine does *not* accept hexadecimal notation.
619 **
620 ** Returns:
621 **
622 **    -1    Not even a prefix of the input text looks like an integer
623 **     0    Successful transformation.  Fits in a 64-bit signed integer.
624 **     1    Excess non-space text after the integer value
625 **     2    Integer too large for a 64-bit signed integer or is malformed
626 **     3    Special case of 9223372036854775808
627 **
628 ** length is the number of bytes in the string (bytes, not characters).
629 ** The string is not necessarily zero-terminated.  The encoding is
630 ** given by enc.
631 */
632 int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
633   int incr;
634   u64 u = 0;
635   int neg = 0; /* assume positive */
636   int i;
637   int c = 0;
638   int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
639   int rc;          /* Baseline return code */
640   const char *zStart;
641   const char *zEnd = zNum + length;
642   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
643   if( enc==SQLITE_UTF8 ){
644     incr = 1;
645   }else{
646     incr = 2;
647     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
648     for(i=3-enc; i<length && zNum[i]==0; i+=2){}
649     nonNum = i<length;
650     zEnd = &zNum[i^1];
651     zNum += (enc&1);
652   }
653   while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
654   if( zNum<zEnd ){
655     if( *zNum=='-' ){
656       neg = 1;
657       zNum+=incr;
658     }else if( *zNum=='+' ){
659       zNum+=incr;
660     }
661   }
662   zStart = zNum;
663   while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
664   for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
665     u = u*10 + c - '0';
666   }
667   testcase( i==18*incr );
668   testcase( i==19*incr );
669   testcase( i==20*incr );
670   if( u>LARGEST_INT64 ){
671     /* This test and assignment is needed only to suppress UB warnings
672     ** from clang and -fsanitize=undefined.  This test and assignment make
673     ** the code a little larger and slower, and no harm comes from omitting
674     ** them, but we must appaise the undefined-behavior pharisees. */
675     *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
676   }else if( neg ){
677     *pNum = -(i64)u;
678   }else{
679     *pNum = (i64)u;
680   }
681   rc = 0;
682   if( i==0 && zStart==zNum ){    /* No digits */
683     rc = -1;
684   }else if( nonNum ){            /* UTF16 with high-order bytes non-zero */
685     rc = 1;
686   }else if( &zNum[i]<zEnd ){     /* Extra bytes at the end */
687     int jj = i;
688     do{
689       if( !sqlite3Isspace(zNum[jj]) ){
690         rc = 1;          /* Extra non-space text after the integer */
691         break;
692       }
693       jj += incr;
694     }while( &zNum[jj]<zEnd );
695   }
696   if( i<19*incr ){
697     /* Less than 19 digits, so we know that it fits in 64 bits */
698     assert( u<=LARGEST_INT64 );
699     return rc;
700   }else{
701     /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
702     c = i>19*incr ? 1 : compare2pow63(zNum, incr);
703     if( c<0 ){
704       /* zNum is less than 9223372036854775808 so it fits */
705       assert( u<=LARGEST_INT64 );
706       return rc;
707     }else{
708       *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
709       if( c>0 ){
710         /* zNum is greater than 9223372036854775808 so it overflows */
711         return 2;
712       }else{
713         /* zNum is exactly 9223372036854775808.  Fits if negative.  The
714         ** special case 2 overflow if positive */
715         assert( u-1==LARGEST_INT64 );
716         return neg ? rc : 3;
717       }
718     }
719   }
720 }
721 
722 /*
723 ** Transform a UTF-8 integer literal, in either decimal or hexadecimal,
724 ** into a 64-bit signed integer.  This routine accepts hexadecimal literals,
725 ** whereas sqlite3Atoi64() does not.
726 **
727 ** Returns:
728 **
729 **     0    Successful transformation.  Fits in a 64-bit signed integer.
730 **     1    Excess text after the integer value
731 **     2    Integer too large for a 64-bit signed integer or is malformed
732 **     3    Special case of 9223372036854775808
733 */
734 int sqlite3DecOrHexToI64(const char *z, i64 *pOut){
735 #ifndef SQLITE_OMIT_HEX_INTEGER
736   if( z[0]=='0'
737    && (z[1]=='x' || z[1]=='X')
738   ){
739     u64 u = 0;
740     int i, k;
741     for(i=2; z[i]=='0'; i++){}
742     for(k=i; sqlite3Isxdigit(z[k]); k++){
743       u = u*16 + sqlite3HexToInt(z[k]);
744     }
745     memcpy(pOut, &u, 8);
746     return (z[k]==0 && k-i<=16) ? 0 : 2;
747   }else
748 #endif /* SQLITE_OMIT_HEX_INTEGER */
749   {
750     return sqlite3Atoi64(z, pOut, sqlite3Strlen30(z), SQLITE_UTF8);
751   }
752 }
753 
754 /*
755 ** If zNum represents an integer that will fit in 32-bits, then set
756 ** *pValue to that integer and return true.  Otherwise return false.
757 **
758 ** This routine accepts both decimal and hexadecimal notation for integers.
759 **
760 ** Any non-numeric characters that following zNum are ignored.
761 ** This is different from sqlite3Atoi64() which requires the
762 ** input number to be zero-terminated.
763 */
764 int sqlite3GetInt32(const char *zNum, int *pValue){
765   sqlite_int64 v = 0;
766   int i, c;
767   int neg = 0;
768   if( zNum[0]=='-' ){
769     neg = 1;
770     zNum++;
771   }else if( zNum[0]=='+' ){
772     zNum++;
773   }
774 #ifndef SQLITE_OMIT_HEX_INTEGER
775   else if( zNum[0]=='0'
776         && (zNum[1]=='x' || zNum[1]=='X')
777         && sqlite3Isxdigit(zNum[2])
778   ){
779     u32 u = 0;
780     zNum += 2;
781     while( zNum[0]=='0' ) zNum++;
782     for(i=0; sqlite3Isxdigit(zNum[i]) && i<8; i++){
783       u = u*16 + sqlite3HexToInt(zNum[i]);
784     }
785     if( (u&0x80000000)==0 && sqlite3Isxdigit(zNum[i])==0 ){
786       memcpy(pValue, &u, 4);
787       return 1;
788     }else{
789       return 0;
790     }
791   }
792 #endif
793   if( !sqlite3Isdigit(zNum[0]) ) return 0;
794   while( zNum[0]=='0' ) zNum++;
795   for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
796     v = v*10 + c;
797   }
798 
799   /* The longest decimal representation of a 32 bit integer is 10 digits:
800   **
801   **             1234567890
802   **     2^31 -> 2147483648
803   */
804   testcase( i==10 );
805   if( i>10 ){
806     return 0;
807   }
808   testcase( v-neg==2147483647 );
809   if( v-neg>2147483647 ){
810     return 0;
811   }
812   if( neg ){
813     v = -v;
814   }
815   *pValue = (int)v;
816   return 1;
817 }
818 
819 /*
820 ** Return a 32-bit integer value extracted from a string.  If the
821 ** string is not an integer, just return 0.
822 */
823 int sqlite3Atoi(const char *z){
824   int x = 0;
825   if( z ) sqlite3GetInt32(z, &x);
826   return x;
827 }
828 
829 /*
830 ** The variable-length integer encoding is as follows:
831 **
832 ** KEY:
833 **         A = 0xxxxxxx    7 bits of data and one flag bit
834 **         B = 1xxxxxxx    7 bits of data and one flag bit
835 **         C = xxxxxxxx    8 bits of data
836 **
837 **  7 bits - A
838 ** 14 bits - BA
839 ** 21 bits - BBA
840 ** 28 bits - BBBA
841 ** 35 bits - BBBBA
842 ** 42 bits - BBBBBA
843 ** 49 bits - BBBBBBA
844 ** 56 bits - BBBBBBBA
845 ** 64 bits - BBBBBBBBC
846 */
847 
848 /*
849 ** Write a 64-bit variable-length integer to memory starting at p[0].
850 ** The length of data write will be between 1 and 9 bytes.  The number
851 ** of bytes written is returned.
852 **
853 ** A variable-length integer consists of the lower 7 bits of each byte
854 ** for all bytes that have the 8th bit set and one byte with the 8th
855 ** bit clear.  Except, if we get to the 9th byte, it stores the full
856 ** 8 bits and is the last byte.
857 */
858 static int SQLITE_NOINLINE putVarint64(unsigned char *p, u64 v){
859   int i, j, n;
860   u8 buf[10];
861   if( v & (((u64)0xff000000)<<32) ){
862     p[8] = (u8)v;
863     v >>= 8;
864     for(i=7; i>=0; i--){
865       p[i] = (u8)((v & 0x7f) | 0x80);
866       v >>= 7;
867     }
868     return 9;
869   }
870   n = 0;
871   do{
872     buf[n++] = (u8)((v & 0x7f) | 0x80);
873     v >>= 7;
874   }while( v!=0 );
875   buf[0] &= 0x7f;
876   assert( n<=9 );
877   for(i=0, j=n-1; j>=0; j--, i++){
878     p[i] = buf[j];
879   }
880   return n;
881 }
882 int sqlite3PutVarint(unsigned char *p, u64 v){
883   if( v<=0x7f ){
884     p[0] = v&0x7f;
885     return 1;
886   }
887   if( v<=0x3fff ){
888     p[0] = ((v>>7)&0x7f)|0x80;
889     p[1] = v&0x7f;
890     return 2;
891   }
892   return putVarint64(p,v);
893 }
894 
895 /*
896 ** Bitmasks used by sqlite3GetVarint().  These precomputed constants
897 ** are defined here rather than simply putting the constant expressions
898 ** inline in order to work around bugs in the RVT compiler.
899 **
900 ** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
901 **
902 ** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
903 */
904 #define SLOT_2_0     0x001fc07f
905 #define SLOT_4_2_0   0xf01fc07f
906 
907 
908 /*
909 ** Read a 64-bit variable-length integer from memory starting at p[0].
910 ** Return the number of bytes read.  The value is stored in *v.
911 */
912 u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
913   u32 a,b,s;
914 
915   if( ((signed char*)p)[0]>=0 ){
916     *v = *p;
917     return 1;
918   }
919   if( ((signed char*)p)[1]>=0 ){
920     *v = ((u32)(p[0]&0x7f)<<7) | p[1];
921     return 2;
922   }
923 
924   /* Verify that constants are precomputed correctly */
925   assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
926   assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
927 
928   a = ((u32)p[0])<<14;
929   b = p[1];
930   p += 2;
931   a |= *p;
932   /* a: p0<<14 | p2 (unmasked) */
933   if (!(a&0x80))
934   {
935     a &= SLOT_2_0;
936     b &= 0x7f;
937     b = b<<7;
938     a |= b;
939     *v = a;
940     return 3;
941   }
942 
943   /* CSE1 from below */
944   a &= SLOT_2_0;
945   p++;
946   b = b<<14;
947   b |= *p;
948   /* b: p1<<14 | p3 (unmasked) */
949   if (!(b&0x80))
950   {
951     b &= SLOT_2_0;
952     /* moved CSE1 up */
953     /* a &= (0x7f<<14)|(0x7f); */
954     a = a<<7;
955     a |= b;
956     *v = a;
957     return 4;
958   }
959 
960   /* a: p0<<14 | p2 (masked) */
961   /* b: p1<<14 | p3 (unmasked) */
962   /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
963   /* moved CSE1 up */
964   /* a &= (0x7f<<14)|(0x7f); */
965   b &= SLOT_2_0;
966   s = a;
967   /* s: p0<<14 | p2 (masked) */
968 
969   p++;
970   a = a<<14;
971   a |= *p;
972   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
973   if (!(a&0x80))
974   {
975     /* we can skip these cause they were (effectively) done above
976     ** while calculating s */
977     /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
978     /* b &= (0x7f<<14)|(0x7f); */
979     b = b<<7;
980     a |= b;
981     s = s>>18;
982     *v = ((u64)s)<<32 | a;
983     return 5;
984   }
985 
986   /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
987   s = s<<7;
988   s |= b;
989   /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
990 
991   p++;
992   b = b<<14;
993   b |= *p;
994   /* b: p1<<28 | p3<<14 | p5 (unmasked) */
995   if (!(b&0x80))
996   {
997     /* we can skip this cause it was (effectively) done above in calc'ing s */
998     /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
999     a &= SLOT_2_0;
1000     a = a<<7;
1001     a |= b;
1002     s = s>>18;
1003     *v = ((u64)s)<<32 | a;
1004     return 6;
1005   }
1006 
1007   p++;
1008   a = a<<14;
1009   a |= *p;
1010   /* a: p2<<28 | p4<<14 | p6 (unmasked) */
1011   if (!(a&0x80))
1012   {
1013     a &= SLOT_4_2_0;
1014     b &= SLOT_2_0;
1015     b = b<<7;
1016     a |= b;
1017     s = s>>11;
1018     *v = ((u64)s)<<32 | a;
1019     return 7;
1020   }
1021 
1022   /* CSE2 from below */
1023   a &= SLOT_2_0;
1024   p++;
1025   b = b<<14;
1026   b |= *p;
1027   /* b: p3<<28 | p5<<14 | p7 (unmasked) */
1028   if (!(b&0x80))
1029   {
1030     b &= SLOT_4_2_0;
1031     /* moved CSE2 up */
1032     /* a &= (0x7f<<14)|(0x7f); */
1033     a = a<<7;
1034     a |= b;
1035     s = s>>4;
1036     *v = ((u64)s)<<32 | a;
1037     return 8;
1038   }
1039 
1040   p++;
1041   a = a<<15;
1042   a |= *p;
1043   /* a: p4<<29 | p6<<15 | p8 (unmasked) */
1044 
1045   /* moved CSE2 up */
1046   /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
1047   b &= SLOT_2_0;
1048   b = b<<8;
1049   a |= b;
1050 
1051   s = s<<4;
1052   b = p[-4];
1053   b &= 0x7f;
1054   b = b>>3;
1055   s |= b;
1056 
1057   *v = ((u64)s)<<32 | a;
1058 
1059   return 9;
1060 }
1061 
1062 /*
1063 ** Read a 32-bit variable-length integer from memory starting at p[0].
1064 ** Return the number of bytes read.  The value is stored in *v.
1065 **
1066 ** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
1067 ** integer, then set *v to 0xffffffff.
1068 **
1069 ** A MACRO version, getVarint32, is provided which inlines the
1070 ** single-byte case.  All code should use the MACRO version as
1071 ** this function assumes the single-byte case has already been handled.
1072 */
1073 u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
1074   u32 a,b;
1075 
1076   /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
1077   ** by the getVarin32() macro */
1078   a = *p;
1079   /* a: p0 (unmasked) */
1080 #ifndef getVarint32
1081   if (!(a&0x80))
1082   {
1083     /* Values between 0 and 127 */
1084     *v = a;
1085     return 1;
1086   }
1087 #endif
1088 
1089   /* The 2-byte case */
1090   p++;
1091   b = *p;
1092   /* b: p1 (unmasked) */
1093   if (!(b&0x80))
1094   {
1095     /* Values between 128 and 16383 */
1096     a &= 0x7f;
1097     a = a<<7;
1098     *v = a | b;
1099     return 2;
1100   }
1101 
1102   /* The 3-byte case */
1103   p++;
1104   a = a<<14;
1105   a |= *p;
1106   /* a: p0<<14 | p2 (unmasked) */
1107   if (!(a&0x80))
1108   {
1109     /* Values between 16384 and 2097151 */
1110     a &= (0x7f<<14)|(0x7f);
1111     b &= 0x7f;
1112     b = b<<7;
1113     *v = a | b;
1114     return 3;
1115   }
1116 
1117   /* A 32-bit varint is used to store size information in btrees.
1118   ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
1119   ** A 3-byte varint is sufficient, for example, to record the size
1120   ** of a 1048569-byte BLOB or string.
1121   **
1122   ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
1123   ** rare larger cases can be handled by the slower 64-bit varint
1124   ** routine.
1125   */
1126 #if 1
1127   {
1128     u64 v64;
1129     u8 n;
1130 
1131     p -= 2;
1132     n = sqlite3GetVarint(p, &v64);
1133     assert( n>3 && n<=9 );
1134     if( (v64 & SQLITE_MAX_U32)!=v64 ){
1135       *v = 0xffffffff;
1136     }else{
1137       *v = (u32)v64;
1138     }
1139     return n;
1140   }
1141 
1142 #else
1143   /* For following code (kept for historical record only) shows an
1144   ** unrolling for the 3- and 4-byte varint cases.  This code is
1145   ** slightly faster, but it is also larger and much harder to test.
1146   */
1147   p++;
1148   b = b<<14;
1149   b |= *p;
1150   /* b: p1<<14 | p3 (unmasked) */
1151   if (!(b&0x80))
1152   {
1153     /* Values between 2097152 and 268435455 */
1154     b &= (0x7f<<14)|(0x7f);
1155     a &= (0x7f<<14)|(0x7f);
1156     a = a<<7;
1157     *v = a | b;
1158     return 4;
1159   }
1160 
1161   p++;
1162   a = a<<14;
1163   a |= *p;
1164   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
1165   if (!(a&0x80))
1166   {
1167     /* Values  between 268435456 and 34359738367 */
1168     a &= SLOT_4_2_0;
1169     b &= SLOT_4_2_0;
1170     b = b<<7;
1171     *v = a | b;
1172     return 5;
1173   }
1174 
1175   /* We can only reach this point when reading a corrupt database
1176   ** file.  In that case we are not in any hurry.  Use the (relatively
1177   ** slow) general-purpose sqlite3GetVarint() routine to extract the
1178   ** value. */
1179   {
1180     u64 v64;
1181     u8 n;
1182 
1183     p -= 4;
1184     n = sqlite3GetVarint(p, &v64);
1185     assert( n>5 && n<=9 );
1186     *v = (u32)v64;
1187     return n;
1188   }
1189 #endif
1190 }
1191 
1192 /*
1193 ** Return the number of bytes that will be needed to store the given
1194 ** 64-bit integer.
1195 */
1196 int sqlite3VarintLen(u64 v){
1197   int i;
1198   for(i=1; (v >>= 7)!=0; i++){ assert( i<10 ); }
1199   return i;
1200 }
1201 
1202 
1203 /*
1204 ** Read or write a four-byte big-endian integer value.
1205 */
1206 u32 sqlite3Get4byte(const u8 *p){
1207 #if SQLITE_BYTEORDER==4321
1208   u32 x;
1209   memcpy(&x,p,4);
1210   return x;
1211 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1212   u32 x;
1213   memcpy(&x,p,4);
1214   return __builtin_bswap32(x);
1215 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1216   u32 x;
1217   memcpy(&x,p,4);
1218   return _byteswap_ulong(x);
1219 #else
1220   testcase( p[0]&0x80 );
1221   return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
1222 #endif
1223 }
1224 void sqlite3Put4byte(unsigned char *p, u32 v){
1225 #if SQLITE_BYTEORDER==4321
1226   memcpy(p,&v,4);
1227 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1228   u32 x = __builtin_bswap32(v);
1229   memcpy(p,&x,4);
1230 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1231   u32 x = _byteswap_ulong(v);
1232   memcpy(p,&x,4);
1233 #else
1234   p[0] = (u8)(v>>24);
1235   p[1] = (u8)(v>>16);
1236   p[2] = (u8)(v>>8);
1237   p[3] = (u8)v;
1238 #endif
1239 }
1240 
1241 
1242 
1243 /*
1244 ** Translate a single byte of Hex into an integer.
1245 ** This routine only works if h really is a valid hexadecimal
1246 ** character:  0..9a..fA..F
1247 */
1248 u8 sqlite3HexToInt(int h){
1249   assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
1250 #ifdef SQLITE_ASCII
1251   h += 9*(1&(h>>6));
1252 #endif
1253 #ifdef SQLITE_EBCDIC
1254   h += 9*(1&~(h>>4));
1255 #endif
1256   return (u8)(h & 0xf);
1257 }
1258 
1259 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
1260 /*
1261 ** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
1262 ** value.  Return a pointer to its binary value.  Space to hold the
1263 ** binary value has been obtained from malloc and must be freed by
1264 ** the calling routine.
1265 */
1266 void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
1267   char *zBlob;
1268   int i;
1269 
1270   zBlob = (char *)sqlite3DbMallocRawNN(db, n/2 + 1);
1271   n--;
1272   if( zBlob ){
1273     for(i=0; i<n; i+=2){
1274       zBlob[i/2] = (sqlite3HexToInt(z[i])<<4) | sqlite3HexToInt(z[i+1]);
1275     }
1276     zBlob[i/2] = 0;
1277   }
1278   return zBlob;
1279 }
1280 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
1281 
1282 /*
1283 ** Log an error that is an API call on a connection pointer that should
1284 ** not have been used.  The "type" of connection pointer is given as the
1285 ** argument.  The zType is a word like "NULL" or "closed" or "invalid".
1286 */
1287 static void logBadConnection(const char *zType){
1288   sqlite3_log(SQLITE_MISUSE,
1289      "API call with %s database connection pointer",
1290      zType
1291   );
1292 }
1293 
1294 /*
1295 ** Check to make sure we have a valid db pointer.  This test is not
1296 ** foolproof but it does provide some measure of protection against
1297 ** misuse of the interface such as passing in db pointers that are
1298 ** NULL or which have been previously closed.  If this routine returns
1299 ** 1 it means that the db pointer is valid and 0 if it should not be
1300 ** dereferenced for any reason.  The calling function should invoke
1301 ** SQLITE_MISUSE immediately.
1302 **
1303 ** sqlite3SafetyCheckOk() requires that the db pointer be valid for
1304 ** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
1305 ** open properly and is not fit for general use but which can be
1306 ** used as an argument to sqlite3_errmsg() or sqlite3_close().
1307 */
1308 int sqlite3SafetyCheckOk(sqlite3 *db){
1309   u32 magic;
1310   if( db==0 ){
1311     logBadConnection("NULL");
1312     return 0;
1313   }
1314   magic = db->magic;
1315   if( magic!=SQLITE_MAGIC_OPEN ){
1316     if( sqlite3SafetyCheckSickOrOk(db) ){
1317       testcase( sqlite3GlobalConfig.xLog!=0 );
1318       logBadConnection("unopened");
1319     }
1320     return 0;
1321   }else{
1322     return 1;
1323   }
1324 }
1325 int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
1326   u32 magic;
1327   magic = db->magic;
1328   if( magic!=SQLITE_MAGIC_SICK &&
1329       magic!=SQLITE_MAGIC_OPEN &&
1330       magic!=SQLITE_MAGIC_BUSY ){
1331     testcase( sqlite3GlobalConfig.xLog!=0 );
1332     logBadConnection("invalid");
1333     return 0;
1334   }else{
1335     return 1;
1336   }
1337 }
1338 
1339 /*
1340 ** Attempt to add, substract, or multiply the 64-bit signed value iB against
1341 ** the other 64-bit signed integer at *pA and store the result in *pA.
1342 ** Return 0 on success.  Or if the operation would have resulted in an
1343 ** overflow, leave *pA unchanged and return 1.
1344 */
1345 int sqlite3AddInt64(i64 *pA, i64 iB){
1346 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1347   return __builtin_add_overflow(*pA, iB, pA);
1348 #else
1349   i64 iA = *pA;
1350   testcase( iA==0 ); testcase( iA==1 );
1351   testcase( iB==-1 ); testcase( iB==0 );
1352   if( iB>=0 ){
1353     testcase( iA>0 && LARGEST_INT64 - iA == iB );
1354     testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
1355     if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
1356   }else{
1357     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
1358     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
1359     if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
1360   }
1361   *pA += iB;
1362   return 0;
1363 #endif
1364 }
1365 int sqlite3SubInt64(i64 *pA, i64 iB){
1366 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1367   return __builtin_sub_overflow(*pA, iB, pA);
1368 #else
1369   testcase( iB==SMALLEST_INT64+1 );
1370   if( iB==SMALLEST_INT64 ){
1371     testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
1372     if( (*pA)>=0 ) return 1;
1373     *pA -= iB;
1374     return 0;
1375   }else{
1376     return sqlite3AddInt64(pA, -iB);
1377   }
1378 #endif
1379 }
1380 int sqlite3MulInt64(i64 *pA, i64 iB){
1381 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1382   return __builtin_mul_overflow(*pA, iB, pA);
1383 #else
1384   i64 iA = *pA;
1385   if( iB>0 ){
1386     if( iA>LARGEST_INT64/iB ) return 1;
1387     if( iA<SMALLEST_INT64/iB ) return 1;
1388   }else if( iB<0 ){
1389     if( iA>0 ){
1390       if( iB<SMALLEST_INT64/iA ) return 1;
1391     }else if( iA<0 ){
1392       if( iB==SMALLEST_INT64 ) return 1;
1393       if( iA==SMALLEST_INT64 ) return 1;
1394       if( -iA>LARGEST_INT64/-iB ) return 1;
1395     }
1396   }
1397   *pA = iA*iB;
1398   return 0;
1399 #endif
1400 }
1401 
1402 /*
1403 ** Compute the absolute value of a 32-bit signed integer, of possible.  Or
1404 ** if the integer has a value of -2147483648, return +2147483647
1405 */
1406 int sqlite3AbsInt32(int x){
1407   if( x>=0 ) return x;
1408   if( x==(int)0x80000000 ) return 0x7fffffff;
1409   return -x;
1410 }
1411 
1412 #ifdef SQLITE_ENABLE_8_3_NAMES
1413 /*
1414 ** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
1415 ** filename in zBaseFilename is a URI with the "8_3_names=1" parameter and
1416 ** if filename in z[] has a suffix (a.k.a. "extension") that is longer than
1417 ** three characters, then shorten the suffix on z[] to be the last three
1418 ** characters of the original suffix.
1419 **
1420 ** If SQLITE_ENABLE_8_3_NAMES is set to 2 at compile-time, then always
1421 ** do the suffix shortening regardless of URI parameter.
1422 **
1423 ** Examples:
1424 **
1425 **     test.db-journal    =>   test.nal
1426 **     test.db-wal        =>   test.wal
1427 **     test.db-shm        =>   test.shm
1428 **     test.db-mj7f3319fa =>   test.9fa
1429 */
1430 void sqlite3FileSuffix3(const char *zBaseFilename, char *z){
1431 #if SQLITE_ENABLE_8_3_NAMES<2
1432   if( sqlite3_uri_boolean(zBaseFilename, "8_3_names", 0) )
1433 #endif
1434   {
1435     int i, sz;
1436     sz = sqlite3Strlen30(z);
1437     for(i=sz-1; i>0 && z[i]!='/' && z[i]!='.'; i--){}
1438     if( z[i]=='.' && ALWAYS(sz>i+4) ) memmove(&z[i+1], &z[sz-3], 4);
1439   }
1440 }
1441 #endif
1442 
1443 /*
1444 ** Find (an approximate) sum of two LogEst values.  This computation is
1445 ** not a simple "+" operator because LogEst is stored as a logarithmic
1446 ** value.
1447 **
1448 */
1449 LogEst sqlite3LogEstAdd(LogEst a, LogEst b){
1450   static const unsigned char x[] = {
1451      10, 10,                         /* 0,1 */
1452       9, 9,                          /* 2,3 */
1453       8, 8,                          /* 4,5 */
1454       7, 7, 7,                       /* 6,7,8 */
1455       6, 6, 6,                       /* 9,10,11 */
1456       5, 5, 5,                       /* 12-14 */
1457       4, 4, 4, 4,                    /* 15-18 */
1458       3, 3, 3, 3, 3, 3,              /* 19-24 */
1459       2, 2, 2, 2, 2, 2, 2,           /* 25-31 */
1460   };
1461   if( a>=b ){
1462     if( a>b+49 ) return a;
1463     if( a>b+31 ) return a+1;
1464     return a+x[a-b];
1465   }else{
1466     if( b>a+49 ) return b;
1467     if( b>a+31 ) return b+1;
1468     return b+x[b-a];
1469   }
1470 }
1471 
1472 /*
1473 ** Convert an integer into a LogEst.  In other words, compute an
1474 ** approximation for 10*log2(x).
1475 */
1476 LogEst sqlite3LogEst(u64 x){
1477   static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 };
1478   LogEst y = 40;
1479   if( x<8 ){
1480     if( x<2 ) return 0;
1481     while( x<8 ){  y -= 10; x <<= 1; }
1482   }else{
1483 #if GCC_VERSION>=5004000
1484     int i = 60 - __builtin_clzll(x);
1485     y += i*10;
1486     x >>= i;
1487 #else
1488     while( x>255 ){ y += 40; x >>= 4; }  /*OPTIMIZATION-IF-TRUE*/
1489     while( x>15 ){  y += 10; x >>= 1; }
1490 #endif
1491   }
1492   return a[x&7] + y - 10;
1493 }
1494 
1495 #ifndef SQLITE_OMIT_VIRTUALTABLE
1496 /*
1497 ** Convert a double into a LogEst
1498 ** In other words, compute an approximation for 10*log2(x).
1499 */
1500 LogEst sqlite3LogEstFromDouble(double x){
1501   u64 a;
1502   LogEst e;
1503   assert( sizeof(x)==8 && sizeof(a)==8 );
1504   if( x<=1 ) return 0;
1505   if( x<=2000000000 ) return sqlite3LogEst((u64)x);
1506   memcpy(&a, &x, 8);
1507   e = (a>>52) - 1022;
1508   return e*10;
1509 }
1510 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1511 
1512 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1513     defined(SQLITE_ENABLE_STAT4) || \
1514     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1515 /*
1516 ** Convert a LogEst into an integer.
1517 **
1518 ** Note that this routine is only used when one or more of various
1519 ** non-standard compile-time options is enabled.
1520 */
1521 u64 sqlite3LogEstToInt(LogEst x){
1522   u64 n;
1523   n = x%10;
1524   x /= 10;
1525   if( n>=5 ) n -= 2;
1526   else if( n>=1 ) n -= 1;
1527 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1528     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1529   if( x>60 ) return (u64)LARGEST_INT64;
1530 #else
1531   /* If only SQLITE_ENABLE_STAT4 is on, then the largest input
1532   ** possible to this routine is 310, resulting in a maximum x of 31 */
1533   assert( x<=60 );
1534 #endif
1535   return x>=3 ? (n+8)<<(x-3) : (n+8)>>(3-x);
1536 }
1537 #endif /* defined SCANSTAT or STAT4 or ESTIMATED_ROWS */
1538 
1539 /*
1540 ** Add a new name/number pair to a VList.  This might require that the
1541 ** VList object be reallocated, so return the new VList.  If an OOM
1542 ** error occurs, the original VList returned and the
1543 ** db->mallocFailed flag is set.
1544 **
1545 ** A VList is really just an array of integers.  To destroy a VList,
1546 ** simply pass it to sqlite3DbFree().
1547 **
1548 ** The first integer is the number of integers allocated for the whole
1549 ** VList.  The second integer is the number of integers actually used.
1550 ** Each name/number pair is encoded by subsequent groups of 3 or more
1551 ** integers.
1552 **
1553 ** Each name/number pair starts with two integers which are the numeric
1554 ** value for the pair and the size of the name/number pair, respectively.
1555 ** The text name overlays one or more following integers.  The text name
1556 ** is always zero-terminated.
1557 **
1558 ** Conceptually:
1559 **
1560 **    struct VList {
1561 **      int nAlloc;   // Number of allocated slots
1562 **      int nUsed;    // Number of used slots
1563 **      struct VListEntry {
1564 **        int iValue;    // Value for this entry
1565 **        int nSlot;     // Slots used by this entry
1566 **        // ... variable name goes here
1567 **      } a[0];
1568 **    }
1569 **
1570 ** During code generation, pointers to the variable names within the
1571 ** VList are taken.  When that happens, nAlloc is set to zero as an
1572 ** indication that the VList may never again be enlarged, since the
1573 ** accompanying realloc() would invalidate the pointers.
1574 */
1575 VList *sqlite3VListAdd(
1576   sqlite3 *db,           /* The database connection used for malloc() */
1577   VList *pIn,            /* The input VList.  Might be NULL */
1578   const char *zName,     /* Name of symbol to add */
1579   int nName,             /* Bytes of text in zName */
1580   int iVal               /* Value to associate with zName */
1581 ){
1582   int nInt;              /* number of sizeof(int) objects needed for zName */
1583   char *z;               /* Pointer to where zName will be stored */
1584   int i;                 /* Index in pIn[] where zName is stored */
1585 
1586   nInt = nName/4 + 3;
1587   assert( pIn==0 || pIn[0]>=3 );  /* Verify ok to add new elements */
1588   if( pIn==0 || pIn[1]+nInt > pIn[0] ){
1589     /* Enlarge the allocation */
1590     sqlite3_int64 nAlloc = (pIn ? 2*(sqlite3_int64)pIn[0] : 10) + nInt;
1591     VList *pOut = sqlite3DbRealloc(db, pIn, nAlloc*sizeof(int));
1592     if( pOut==0 ) return pIn;
1593     if( pIn==0 ) pOut[1] = 2;
1594     pIn = pOut;
1595     pIn[0] = nAlloc;
1596   }
1597   i = pIn[1];
1598   pIn[i] = iVal;
1599   pIn[i+1] = nInt;
1600   z = (char*)&pIn[i+2];
1601   pIn[1] = i+nInt;
1602   assert( pIn[1]<=pIn[0] );
1603   memcpy(z, zName, nName);
1604   z[nName] = 0;
1605   return pIn;
1606 }
1607 
1608 /*
1609 ** Return a pointer to the name of a variable in the given VList that
1610 ** has the value iVal.  Or return a NULL if there is no such variable in
1611 ** the list
1612 */
1613 const char *sqlite3VListNumToName(VList *pIn, int iVal){
1614   int i, mx;
1615   if( pIn==0 ) return 0;
1616   mx = pIn[1];
1617   i = 2;
1618   do{
1619     if( pIn[i]==iVal ) return (char*)&pIn[i+2];
1620     i += pIn[i+1];
1621   }while( i<mx );
1622   return 0;
1623 }
1624 
1625 /*
1626 ** Return the number of the variable named zName, if it is in VList.
1627 ** or return 0 if there is no such variable.
1628 */
1629 int sqlite3VListNameToNum(VList *pIn, const char *zName, int nName){
1630   int i, mx;
1631   if( pIn==0 ) return 0;
1632   mx = pIn[1];
1633   i = 2;
1634   do{
1635     const char *z = (const char*)&pIn[i+2];
1636     if( strncmp(z,zName,nName)==0 && z[nName]==0 ) return pIn[i];
1637     i += pIn[i+1];
1638   }while( i<mx );
1639   return 0;
1640 }
1641