xref: /sqlite-3.40.0/src/util.c (revision b88eaf16)
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 #include <math.h>
21 
22 /*
23 ** Routine needed to support the testcase() macro.
24 */
25 #ifdef SQLITE_COVERAGE_TEST
26 void sqlite3Coverage(int x){
27   static unsigned dummy = 0;
28   dummy += (unsigned)x;
29 }
30 #endif
31 
32 /*
33 ** Calls to sqlite3FaultSim() are used to simulate a failure during testing,
34 ** or to bypass normal error detection during testing in order to let
35 ** execute proceed futher downstream.
36 **
37 ** In deployment, sqlite3FaultSim() *always* return SQLITE_OK (0).  The
38 ** sqlite3FaultSim() function only returns non-zero during testing.
39 **
40 ** During testing, if the test harness has set a fault-sim callback using
41 ** a call to sqlite3_test_control(SQLITE_TESTCTRL_FAULT_INSTALL), then
42 ** each call to sqlite3FaultSim() is relayed to that application-supplied
43 ** callback and the integer return value form the application-supplied
44 ** callback is returned by sqlite3FaultSim().
45 **
46 ** The integer argument to sqlite3FaultSim() is a code to identify which
47 ** sqlite3FaultSim() instance is being invoked. Each call to sqlite3FaultSim()
48 ** should have a unique code.  To prevent legacy testing applications from
49 ** breaking, the codes should not be changed or reused.
50 */
51 #ifndef SQLITE_UNTESTABLE
52 int sqlite3FaultSim(int iTest){
53   int (*xCallback)(int) = sqlite3GlobalConfig.xTestCallback;
54   return xCallback ? xCallback(iTest) : SQLITE_OK;
55 }
56 #endif
57 
58 #ifndef SQLITE_OMIT_FLOATING_POINT
59 /*
60 ** Return true if the floating point value is Not a Number (NaN).
61 */
62 int sqlite3IsNaN(double x){
63   u64 y;
64   memcpy(&y,&x,sizeof(y));
65   return IsNaN(y);
66 }
67 #endif /* SQLITE_OMIT_FLOATING_POINT */
68 
69 /*
70 ** Compute a string length that is limited to what can be stored in
71 ** lower 30 bits of a 32-bit signed integer.
72 **
73 ** The value returned will never be negative.  Nor will it ever be greater
74 ** than the actual length of the string.  For very long strings (greater
75 ** than 1GiB) the value returned might be less than the true string length.
76 */
77 int sqlite3Strlen30(const char *z){
78   if( z==0 ) return 0;
79   return 0x3fffffff & (int)strlen(z);
80 }
81 
82 /*
83 ** Return the declared type of a column.  Or return zDflt if the column
84 ** has no declared type.
85 **
86 ** The column type is an extra string stored after the zero-terminator on
87 ** the column name if and only if the COLFLAG_HASTYPE flag is set.
88 */
89 char *sqlite3ColumnType(Column *pCol, char *zDflt){
90   if( (pCol->colFlags & COLFLAG_HASTYPE)==0 ) return zDflt;
91   return pCol->zName + strlen(pCol->zName) + 1;
92 }
93 
94 /*
95 ** Helper function for sqlite3Error() - called rarely.  Broken out into
96 ** a separate routine to avoid unnecessary register saves on entry to
97 ** sqlite3Error().
98 */
99 static SQLITE_NOINLINE void  sqlite3ErrorFinish(sqlite3 *db, int err_code){
100   if( db->pErr ) sqlite3ValueSetNull(db->pErr);
101   sqlite3SystemError(db, err_code);
102 }
103 
104 /*
105 ** Set the current error code to err_code and clear any prior error message.
106 ** Also set iSysErrno (by calling sqlite3System) if the err_code indicates
107 ** that would be appropriate.
108 */
109 void sqlite3Error(sqlite3 *db, int err_code){
110   assert( db!=0 );
111   db->errCode = err_code;
112   if( err_code || db->pErr ) sqlite3ErrorFinish(db, err_code);
113 }
114 
115 /*
116 ** Load the sqlite3.iSysErrno field if that is an appropriate thing
117 ** to do based on the SQLite error code in rc.
118 */
119 void sqlite3SystemError(sqlite3 *db, int rc){
120   if( rc==SQLITE_IOERR_NOMEM ) return;
121   rc &= 0xff;
122   if( rc==SQLITE_CANTOPEN || rc==SQLITE_IOERR ){
123     db->iSysErrno = sqlite3OsGetLastError(db->pVfs);
124   }
125 }
126 
127 /*
128 ** Set the most recent error code and error string for the sqlite
129 ** handle "db". The error code is set to "err_code".
130 **
131 ** If it is not NULL, string zFormat specifies the format of the
132 ** error string in the style of the printf functions: The following
133 ** format characters are allowed:
134 **
135 **      %s      Insert a string
136 **      %z      A string that should be freed after use
137 **      %d      Insert an integer
138 **      %T      Insert a token
139 **      %S      Insert the first element of a SrcList
140 **
141 ** zFormat and any string tokens that follow it are assumed to be
142 ** encoded in UTF-8.
143 **
144 ** To clear the most recent error for sqlite handle "db", sqlite3Error
145 ** should be called with err_code set to SQLITE_OK and zFormat set
146 ** to NULL.
147 */
148 void sqlite3ErrorWithMsg(sqlite3 *db, int err_code, const char *zFormat, ...){
149   assert( db!=0 );
150   db->errCode = err_code;
151   sqlite3SystemError(db, err_code);
152   if( zFormat==0 ){
153     sqlite3Error(db, err_code);
154   }else if( db->pErr || (db->pErr = sqlite3ValueNew(db))!=0 ){
155     char *z;
156     va_list ap;
157     va_start(ap, zFormat);
158     z = sqlite3VMPrintf(db, zFormat, ap);
159     va_end(ap);
160     sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
161   }
162 }
163 
164 /*
165 ** Add an error message to pParse->zErrMsg and increment pParse->nErr.
166 ** The following formatting characters are allowed:
167 **
168 **      %s      Insert a string
169 **      %z      A string that should be freed after use
170 **      %d      Insert an integer
171 **      %T      Insert a token
172 **      %S      Insert the first element of a SrcList
173 **
174 ** This function should be used to report any error that occurs while
175 ** compiling an SQL statement (i.e. within sqlite3_prepare()). The
176 ** last thing the sqlite3_prepare() function does is copy the error
177 ** stored by this function into the database handle using sqlite3Error().
178 ** Functions sqlite3Error() or sqlite3ErrorWithMsg() should be used
179 ** during statement execution (sqlite3_step() etc.).
180 */
181 void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
182   char *zMsg;
183   va_list ap;
184   sqlite3 *db = pParse->db;
185   va_start(ap, zFormat);
186   zMsg = sqlite3VMPrintf(db, zFormat, ap);
187   va_end(ap);
188   if( db->suppressErr ){
189     sqlite3DbFree(db, zMsg);
190   }else{
191     pParse->nErr++;
192     sqlite3DbFree(db, pParse->zErrMsg);
193     pParse->zErrMsg = zMsg;
194     pParse->rc = SQLITE_ERROR;
195     pParse->pWith = 0;
196   }
197 }
198 
199 /*
200 ** If database connection db is currently parsing SQL, then transfer
201 ** error code errCode to that parser if the parser has not already
202 ** encountered some other kind of error.
203 */
204 int sqlite3ErrorToParser(sqlite3 *db, int errCode){
205   Parse *pParse;
206   if( db==0 || (pParse = db->pParse)==0 ) return errCode;
207   pParse->rc = errCode;
208   pParse->nErr++;
209   return errCode;
210 }
211 
212 /*
213 ** Convert an SQL-style quoted string into a normal string by removing
214 ** the quote characters.  The conversion is done in-place.  If the
215 ** input does not begin with a quote character, then this routine
216 ** is a no-op.
217 **
218 ** The input string must be zero-terminated.  A new zero-terminator
219 ** is added to the dequoted string.
220 **
221 ** The return value is -1 if no dequoting occurs or the length of the
222 ** dequoted string, exclusive of the zero terminator, if dequoting does
223 ** occur.
224 **
225 ** 2002-02-14: This routine is extended to remove MS-Access style
226 ** brackets from around identifiers.  For example:  "[a-b-c]" becomes
227 ** "a-b-c".
228 */
229 void sqlite3Dequote(char *z){
230   char quote;
231   int i, j;
232   if( z==0 ) return;
233   quote = z[0];
234   if( !sqlite3Isquote(quote) ) return;
235   if( quote=='[' ) quote = ']';
236   for(i=1, j=0;; i++){
237     assert( z[i] );
238     if( z[i]==quote ){
239       if( z[i+1]==quote ){
240         z[j++] = quote;
241         i++;
242       }else{
243         break;
244       }
245     }else{
246       z[j++] = z[i];
247     }
248   }
249   z[j] = 0;
250 }
251 void sqlite3DequoteExpr(Expr *p){
252   assert( sqlite3Isquote(p->u.zToken[0]) );
253   p->flags |= p->u.zToken[0]=='"' ? EP_Quoted|EP_DblQuoted : EP_Quoted;
254   sqlite3Dequote(p->u.zToken);
255 }
256 
257 /*
258 ** Generate a Token object from a string
259 */
260 void sqlite3TokenInit(Token *p, char *z){
261   p->z = z;
262   p->n = sqlite3Strlen30(z);
263 }
264 
265 /* Convenient short-hand */
266 #define UpperToLower sqlite3UpperToLower
267 
268 /*
269 ** Some systems have stricmp().  Others have strcasecmp().  Because
270 ** there is no consistency, we will define our own.
271 **
272 ** IMPLEMENTATION-OF: R-30243-02494 The sqlite3_stricmp() and
273 ** sqlite3_strnicmp() APIs allow applications and extensions to compare
274 ** the contents of two buffers containing UTF-8 strings in a
275 ** case-independent fashion, using the same definition of "case
276 ** independence" that SQLite uses internally when comparing identifiers.
277 */
278 int sqlite3_stricmp(const char *zLeft, const char *zRight){
279   if( zLeft==0 ){
280     return zRight ? -1 : 0;
281   }else if( zRight==0 ){
282     return 1;
283   }
284   return sqlite3StrICmp(zLeft, zRight);
285 }
286 int sqlite3StrICmp(const char *zLeft, const char *zRight){
287   unsigned char *a, *b;
288   int c, x;
289   a = (unsigned char *)zLeft;
290   b = (unsigned char *)zRight;
291   for(;;){
292     c = *a;
293     x = *b;
294     if( c==x ){
295       if( c==0 ) break;
296     }else{
297       c = (int)UpperToLower[c] - (int)UpperToLower[x];
298       if( c ) break;
299     }
300     a++;
301     b++;
302   }
303   return c;
304 }
305 int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
306   register unsigned char *a, *b;
307   if( zLeft==0 ){
308     return zRight ? -1 : 0;
309   }else if( zRight==0 ){
310     return 1;
311   }
312   a = (unsigned char *)zLeft;
313   b = (unsigned char *)zRight;
314   while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
315   return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
316 }
317 
318 /*
319 ** Compute 10 to the E-th power.  Examples:  E==1 results in 10.
320 ** E==2 results in 100.  E==50 results in 1.0e50.
321 **
322 ** This routine only works for values of E between 1 and 341.
323 */
324 static LONGDOUBLE_TYPE sqlite3Pow10(int E){
325 #if defined(_MSC_VER)
326   static const LONGDOUBLE_TYPE x[] = {
327     1.0e+001L,
328     1.0e+002L,
329     1.0e+004L,
330     1.0e+008L,
331     1.0e+016L,
332     1.0e+032L,
333     1.0e+064L,
334     1.0e+128L,
335     1.0e+256L
336   };
337   LONGDOUBLE_TYPE r = 1.0;
338   int i;
339   assert( E>=0 && E<=307 );
340   for(i=0; E!=0; i++, E >>=1){
341     if( E & 1 ) r *= x[i];
342   }
343   return r;
344 #else
345   LONGDOUBLE_TYPE x = 10.0;
346   LONGDOUBLE_TYPE r = 1.0;
347   while(1){
348     if( E & 1 ) r *= x;
349     E >>= 1;
350     if( E==0 ) break;
351     x *= x;
352   }
353   return r;
354 #endif
355 }
356 
357 /*
358 ** The string z[] is an text representation of a real number.
359 ** Convert this string to a double and write it into *pResult.
360 **
361 ** The string z[] is length bytes in length (bytes, not characters) and
362 ** uses the encoding enc.  The string is not necessarily zero-terminated.
363 **
364 ** Return TRUE if the result is a valid real number (or integer) and FALSE
365 ** if the string is empty or contains extraneous text.  More specifically
366 ** return
367 **      1          =>  The input string is a pure integer
368 **      2 or more  =>  The input has a decimal point or eNNN clause
369 **      0 or less  =>  The input string is not a valid number
370 **     -1          =>  Not a valid number, but has a valid prefix which
371 **                     includes a decimal point and/or an eNNN clause
372 **
373 ** Valid numbers are in one of these formats:
374 **
375 **    [+-]digits[E[+-]digits]
376 **    [+-]digits.[digits][E[+-]digits]
377 **    [+-].digits[E[+-]digits]
378 **
379 ** Leading and trailing whitespace is ignored for the purpose of determining
380 ** validity.
381 **
382 ** If some prefix of the input string is a valid number, this routine
383 ** returns FALSE but it still converts the prefix and writes the result
384 ** into *pResult.
385 */
386 #if defined(_MSC_VER)
387 #pragma warning(disable : 4756)
388 #endif
389 int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
390 #ifndef SQLITE_OMIT_FLOATING_POINT
391   int incr;
392   const char *zEnd = z + length;
393   /* sign * significand * (10 ^ (esign * exponent)) */
394   int sign = 1;    /* sign of significand */
395   i64 s = 0;       /* significand */
396   int d = 0;       /* adjust exponent for shifting decimal point */
397   int esign = 1;   /* sign of exponent */
398   int e = 0;       /* exponent */
399   int eValid = 1;  /* True exponent is either not used or is well-formed */
400   double result;
401   int nDigit = 0;  /* Number of digits processed */
402   int eType = 1;   /* 1: pure integer,  2+: fractional  -1 or less: bad UTF16 */
403 
404   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
405   *pResult = 0.0;   /* Default return value, in case of an error */
406 
407   if( enc==SQLITE_UTF8 ){
408     incr = 1;
409   }else{
410     int i;
411     incr = 2;
412     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
413     testcase( enc==SQLITE_UTF16LE );
414     testcase( enc==SQLITE_UTF16BE );
415     for(i=3-enc; i<length && z[i]==0; i+=2){}
416     if( i<length ) eType = -100;
417     zEnd = &z[i^1];
418     z += (enc&1);
419   }
420 
421   /* skip leading spaces */
422   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
423   if( z>=zEnd ) return 0;
424 
425   /* get sign of significand */
426   if( *z=='-' ){
427     sign = -1;
428     z+=incr;
429   }else if( *z=='+' ){
430     z+=incr;
431   }
432 
433   /* copy max significant digits to significand */
434   while( z<zEnd && sqlite3Isdigit(*z) ){
435     s = s*10 + (*z - '0');
436     z+=incr; nDigit++;
437     if( s>=((LARGEST_INT64-9)/10) ){
438       /* skip non-significant significand digits
439       ** (increase exponent by d to shift decimal left) */
440       while( z<zEnd && sqlite3Isdigit(*z) ){ z+=incr; d++; }
441     }
442   }
443   if( z>=zEnd ) goto do_atof_calc;
444 
445   /* if decimal point is present */
446   if( *z=='.' ){
447     z+=incr;
448     eType++;
449     /* copy digits from after decimal to significand
450     ** (decrease exponent by d to shift decimal right) */
451     while( z<zEnd && sqlite3Isdigit(*z) ){
452       if( s<((LARGEST_INT64-9)/10) ){
453         s = s*10 + (*z - '0');
454         d--;
455         nDigit++;
456       }
457       z+=incr;
458     }
459   }
460   if( z>=zEnd ) goto do_atof_calc;
461 
462   /* if exponent is present */
463   if( *z=='e' || *z=='E' ){
464     z+=incr;
465     eValid = 0;
466     eType++;
467 
468     /* This branch is needed to avoid a (harmless) buffer overread.  The
469     ** special comment alerts the mutation tester that the correct answer
470     ** is obtained even if the branch is omitted */
471     if( z>=zEnd ) goto do_atof_calc;              /*PREVENTS-HARMLESS-OVERREAD*/
472 
473     /* get sign of exponent */
474     if( *z=='-' ){
475       esign = -1;
476       z+=incr;
477     }else if( *z=='+' ){
478       z+=incr;
479     }
480     /* copy digits to exponent */
481     while( z<zEnd && sqlite3Isdigit(*z) ){
482       e = e<10000 ? (e*10 + (*z - '0')) : 10000;
483       z+=incr;
484       eValid = 1;
485     }
486   }
487 
488   /* skip trailing spaces */
489   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
490 
491 do_atof_calc:
492   /* adjust exponent by d, and update sign */
493   e = (e*esign) + d;
494   if( e<0 ) {
495     esign = -1;
496     e *= -1;
497   } else {
498     esign = 1;
499   }
500 
501   if( s==0 ) {
502     /* In the IEEE 754 standard, zero is signed. */
503     result = sign<0 ? -(double)0 : (double)0;
504   } else {
505     /* Attempt to reduce exponent.
506     **
507     ** Branches that are not required for the correct answer but which only
508     ** help to obtain the correct answer faster are marked with special
509     ** comments, as a hint to the mutation tester.
510     */
511     while( e>0 ){                                       /*OPTIMIZATION-IF-TRUE*/
512       if( esign>0 ){
513         if( s>=(LARGEST_INT64/10) ) break;             /*OPTIMIZATION-IF-FALSE*/
514         s *= 10;
515       }else{
516         if( s%10!=0 ) break;                           /*OPTIMIZATION-IF-FALSE*/
517         s /= 10;
518       }
519       e--;
520     }
521 
522     /* adjust the sign of significand */
523     s = sign<0 ? -s : s;
524 
525     if( e==0 ){                                         /*OPTIMIZATION-IF-TRUE*/
526       result = (double)s;
527     }else{
528       /* attempt to handle extremely small/large numbers better */
529       if( e>307 ){                                      /*OPTIMIZATION-IF-TRUE*/
530         if( e<342 ){                                    /*OPTIMIZATION-IF-TRUE*/
531           LONGDOUBLE_TYPE scale = sqlite3Pow10(e-308);
532           if( esign<0 ){
533             result = s / scale;
534             result /= 1.0e+308;
535           }else{
536             result = s * scale;
537             result *= 1.0e+308;
538           }
539         }else{ assert( e>=342 );
540           if( esign<0 ){
541             result = 0.0*s;
542           }else{
543 #ifdef INFINITY
544             result = INFINITY*s;
545 #else
546             result = 1e308*1e308*s;  /* Infinity */
547 #endif
548           }
549         }
550       }else{
551         LONGDOUBLE_TYPE scale = sqlite3Pow10(e);
552         if( esign<0 ){
553           result = s / scale;
554         }else{
555           result = s * scale;
556         }
557       }
558     }
559   }
560 
561   /* store the result */
562   *pResult = result;
563 
564   /* return true if number and no extra non-whitespace chracters after */
565   if( z==zEnd && nDigit>0 && eValid && eType>0 ){
566     return eType;
567   }else if( eType>=2 && (eType==3 || eValid) && nDigit>0 ){
568     return -1;
569   }else{
570     return 0;
571   }
572 #else
573   return !sqlite3Atoi64(z, pResult, length, enc);
574 #endif /* SQLITE_OMIT_FLOATING_POINT */
575 }
576 #if defined(_MSC_VER)
577 #pragma warning(default : 4756)
578 #endif
579 
580 /*
581 ** Compare the 19-character string zNum against the text representation
582 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive
583 ** if zNum is less than, equal to, or greater than the string.
584 ** Note that zNum must contain exactly 19 characters.
585 **
586 ** Unlike memcmp() this routine is guaranteed to return the difference
587 ** in the values of the last digit if the only difference is in the
588 ** last digit.  So, for example,
589 **
590 **      compare2pow63("9223372036854775800", 1)
591 **
592 ** will return -8.
593 */
594 static int compare2pow63(const char *zNum, int incr){
595   int c = 0;
596   int i;
597                     /* 012345678901234567 */
598   const char *pow63 = "922337203685477580";
599   for(i=0; c==0 && i<18; i++){
600     c = (zNum[i*incr]-pow63[i])*10;
601   }
602   if( c==0 ){
603     c = zNum[18*incr] - '8';
604     testcase( c==(-1) );
605     testcase( c==0 );
606     testcase( c==(+1) );
607   }
608   return c;
609 }
610 
611 /*
612 ** Convert zNum to a 64-bit signed integer.  zNum must be decimal. This
613 ** routine does *not* accept hexadecimal notation.
614 **
615 ** Returns:
616 **
617 **    -1    Not even a prefix of the input text looks like an integer
618 **     0    Successful transformation.  Fits in a 64-bit signed integer.
619 **     1    Excess non-space text after the integer value
620 **     2    Integer too large for a 64-bit signed integer or is malformed
621 **     3    Special case of 9223372036854775808
622 **
623 ** length is the number of bytes in the string (bytes, not characters).
624 ** The string is not necessarily zero-terminated.  The encoding is
625 ** given by enc.
626 */
627 int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
628   int incr;
629   u64 u = 0;
630   int neg = 0; /* assume positive */
631   int i;
632   int c = 0;
633   int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
634   int rc;          /* Baseline return code */
635   const char *zStart;
636   const char *zEnd = zNum + length;
637   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
638   if( enc==SQLITE_UTF8 ){
639     incr = 1;
640   }else{
641     incr = 2;
642     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
643     for(i=3-enc; i<length && zNum[i]==0; i+=2){}
644     nonNum = i<length;
645     zEnd = &zNum[i^1];
646     zNum += (enc&1);
647   }
648   while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
649   if( zNum<zEnd ){
650     if( *zNum=='-' ){
651       neg = 1;
652       zNum+=incr;
653     }else if( *zNum=='+' ){
654       zNum+=incr;
655     }
656   }
657   zStart = zNum;
658   while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
659   for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
660     u = u*10 + c - '0';
661   }
662   testcase( i==18*incr );
663   testcase( i==19*incr );
664   testcase( i==20*incr );
665   if( u>LARGEST_INT64 ){
666     /* This test and assignment is needed only to suppress UB warnings
667     ** from clang and -fsanitize=undefined.  This test and assignment make
668     ** the code a little larger and slower, and no harm comes from omitting
669     ** them, but we must appaise the undefined-behavior pharisees. */
670     *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
671   }else if( neg ){
672     *pNum = -(i64)u;
673   }else{
674     *pNum = (i64)u;
675   }
676   rc = 0;
677   if( i==0 && zStart==zNum ){    /* No digits */
678     rc = -1;
679   }else if( nonNum ){            /* UTF16 with high-order bytes non-zero */
680     rc = 1;
681   }else if( &zNum[i]<zEnd ){     /* Extra bytes at the end */
682     int jj = i;
683     do{
684       if( !sqlite3Isspace(zNum[jj]) ){
685         rc = 1;          /* Extra non-space text after the integer */
686         break;
687       }
688       jj += incr;
689     }while( &zNum[jj]<zEnd );
690   }
691   if( i<19*incr ){
692     /* Less than 19 digits, so we know that it fits in 64 bits */
693     assert( u<=LARGEST_INT64 );
694     return rc;
695   }else{
696     /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
697     c = i>19*incr ? 1 : compare2pow63(zNum, incr);
698     if( c<0 ){
699       /* zNum is less than 9223372036854775808 so it fits */
700       assert( u<=LARGEST_INT64 );
701       return rc;
702     }else{
703       *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
704       if( c>0 ){
705         /* zNum is greater than 9223372036854775808 so it overflows */
706         return 2;
707       }else{
708         /* zNum is exactly 9223372036854775808.  Fits if negative.  The
709         ** special case 2 overflow if positive */
710         assert( u-1==LARGEST_INT64 );
711         return neg ? rc : 3;
712       }
713     }
714   }
715 }
716 
717 /*
718 ** Transform a UTF-8 integer literal, in either decimal or hexadecimal,
719 ** into a 64-bit signed integer.  This routine accepts hexadecimal literals,
720 ** whereas sqlite3Atoi64() does not.
721 **
722 ** Returns:
723 **
724 **     0    Successful transformation.  Fits in a 64-bit signed integer.
725 **     1    Excess text after the integer value
726 **     2    Integer too large for a 64-bit signed integer or is malformed
727 **     3    Special case of 9223372036854775808
728 */
729 int sqlite3DecOrHexToI64(const char *z, i64 *pOut){
730 #ifndef SQLITE_OMIT_HEX_INTEGER
731   if( z[0]=='0'
732    && (z[1]=='x' || z[1]=='X')
733   ){
734     u64 u = 0;
735     int i, k;
736     for(i=2; z[i]=='0'; i++){}
737     for(k=i; sqlite3Isxdigit(z[k]); k++){
738       u = u*16 + sqlite3HexToInt(z[k]);
739     }
740     memcpy(pOut, &u, 8);
741     return (z[k]==0 && k-i<=16) ? 0 : 2;
742   }else
743 #endif /* SQLITE_OMIT_HEX_INTEGER */
744   {
745     return sqlite3Atoi64(z, pOut, sqlite3Strlen30(z), SQLITE_UTF8);
746   }
747 }
748 
749 /*
750 ** If zNum represents an integer that will fit in 32-bits, then set
751 ** *pValue to that integer and return true.  Otherwise return false.
752 **
753 ** This routine accepts both decimal and hexadecimal notation for integers.
754 **
755 ** Any non-numeric characters that following zNum are ignored.
756 ** This is different from sqlite3Atoi64() which requires the
757 ** input number to be zero-terminated.
758 */
759 int sqlite3GetInt32(const char *zNum, int *pValue){
760   sqlite_int64 v = 0;
761   int i, c;
762   int neg = 0;
763   if( zNum[0]=='-' ){
764     neg = 1;
765     zNum++;
766   }else if( zNum[0]=='+' ){
767     zNum++;
768   }
769 #ifndef SQLITE_OMIT_HEX_INTEGER
770   else if( zNum[0]=='0'
771         && (zNum[1]=='x' || zNum[1]=='X')
772         && sqlite3Isxdigit(zNum[2])
773   ){
774     u32 u = 0;
775     zNum += 2;
776     while( zNum[0]=='0' ) zNum++;
777     for(i=0; sqlite3Isxdigit(zNum[i]) && i<8; i++){
778       u = u*16 + sqlite3HexToInt(zNum[i]);
779     }
780     if( (u&0x80000000)==0 && sqlite3Isxdigit(zNum[i])==0 ){
781       memcpy(pValue, &u, 4);
782       return 1;
783     }else{
784       return 0;
785     }
786   }
787 #endif
788   if( !sqlite3Isdigit(zNum[0]) ) return 0;
789   while( zNum[0]=='0' ) zNum++;
790   for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
791     v = v*10 + c;
792   }
793 
794   /* The longest decimal representation of a 32 bit integer is 10 digits:
795   **
796   **             1234567890
797   **     2^31 -> 2147483648
798   */
799   testcase( i==10 );
800   if( i>10 ){
801     return 0;
802   }
803   testcase( v-neg==2147483647 );
804   if( v-neg>2147483647 ){
805     return 0;
806   }
807   if( neg ){
808     v = -v;
809   }
810   *pValue = (int)v;
811   return 1;
812 }
813 
814 /*
815 ** Return a 32-bit integer value extracted from a string.  If the
816 ** string is not an integer, just return 0.
817 */
818 int sqlite3Atoi(const char *z){
819   int x = 0;
820   if( z ) sqlite3GetInt32(z, &x);
821   return x;
822 }
823 
824 /*
825 ** The variable-length integer encoding is as follows:
826 **
827 ** KEY:
828 **         A = 0xxxxxxx    7 bits of data and one flag bit
829 **         B = 1xxxxxxx    7 bits of data and one flag bit
830 **         C = xxxxxxxx    8 bits of data
831 **
832 **  7 bits - A
833 ** 14 bits - BA
834 ** 21 bits - BBA
835 ** 28 bits - BBBA
836 ** 35 bits - BBBBA
837 ** 42 bits - BBBBBA
838 ** 49 bits - BBBBBBA
839 ** 56 bits - BBBBBBBA
840 ** 64 bits - BBBBBBBBC
841 */
842 
843 /*
844 ** Write a 64-bit variable-length integer to memory starting at p[0].
845 ** The length of data write will be between 1 and 9 bytes.  The number
846 ** of bytes written is returned.
847 **
848 ** A variable-length integer consists of the lower 7 bits of each byte
849 ** for all bytes that have the 8th bit set and one byte with the 8th
850 ** bit clear.  Except, if we get to the 9th byte, it stores the full
851 ** 8 bits and is the last byte.
852 */
853 static int SQLITE_NOINLINE putVarint64(unsigned char *p, u64 v){
854   int i, j, n;
855   u8 buf[10];
856   if( v & (((u64)0xff000000)<<32) ){
857     p[8] = (u8)v;
858     v >>= 8;
859     for(i=7; i>=0; i--){
860       p[i] = (u8)((v & 0x7f) | 0x80);
861       v >>= 7;
862     }
863     return 9;
864   }
865   n = 0;
866   do{
867     buf[n++] = (u8)((v & 0x7f) | 0x80);
868     v >>= 7;
869   }while( v!=0 );
870   buf[0] &= 0x7f;
871   assert( n<=9 );
872   for(i=0, j=n-1; j>=0; j--, i++){
873     p[i] = buf[j];
874   }
875   return n;
876 }
877 int sqlite3PutVarint(unsigned char *p, u64 v){
878   if( v<=0x7f ){
879     p[0] = v&0x7f;
880     return 1;
881   }
882   if( v<=0x3fff ){
883     p[0] = ((v>>7)&0x7f)|0x80;
884     p[1] = v&0x7f;
885     return 2;
886   }
887   return putVarint64(p,v);
888 }
889 
890 /*
891 ** Bitmasks used by sqlite3GetVarint().  These precomputed constants
892 ** are defined here rather than simply putting the constant expressions
893 ** inline in order to work around bugs in the RVT compiler.
894 **
895 ** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
896 **
897 ** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
898 */
899 #define SLOT_2_0     0x001fc07f
900 #define SLOT_4_2_0   0xf01fc07f
901 
902 
903 /*
904 ** Read a 64-bit variable-length integer from memory starting at p[0].
905 ** Return the number of bytes read.  The value is stored in *v.
906 */
907 u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
908   u32 a,b,s;
909 
910   if( ((signed char*)p)[0]>=0 ){
911     *v = *p;
912     return 1;
913   }
914   if( ((signed char*)p)[1]>=0 ){
915     *v = ((u32)(p[0]&0x7f)<<7) | p[1];
916     return 2;
917   }
918 
919   /* Verify that constants are precomputed correctly */
920   assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
921   assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
922 
923   a = ((u32)p[0])<<14;
924   b = p[1];
925   p += 2;
926   a |= *p;
927   /* a: p0<<14 | p2 (unmasked) */
928   if (!(a&0x80))
929   {
930     a &= SLOT_2_0;
931     b &= 0x7f;
932     b = b<<7;
933     a |= b;
934     *v = a;
935     return 3;
936   }
937 
938   /* CSE1 from below */
939   a &= SLOT_2_0;
940   p++;
941   b = b<<14;
942   b |= *p;
943   /* b: p1<<14 | p3 (unmasked) */
944   if (!(b&0x80))
945   {
946     b &= SLOT_2_0;
947     /* moved CSE1 up */
948     /* a &= (0x7f<<14)|(0x7f); */
949     a = a<<7;
950     a |= b;
951     *v = a;
952     return 4;
953   }
954 
955   /* a: p0<<14 | p2 (masked) */
956   /* b: p1<<14 | p3 (unmasked) */
957   /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
958   /* moved CSE1 up */
959   /* a &= (0x7f<<14)|(0x7f); */
960   b &= SLOT_2_0;
961   s = a;
962   /* s: p0<<14 | p2 (masked) */
963 
964   p++;
965   a = a<<14;
966   a |= *p;
967   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
968   if (!(a&0x80))
969   {
970     /* we can skip these cause they were (effectively) done above
971     ** while calculating s */
972     /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
973     /* b &= (0x7f<<14)|(0x7f); */
974     b = b<<7;
975     a |= b;
976     s = s>>18;
977     *v = ((u64)s)<<32 | a;
978     return 5;
979   }
980 
981   /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
982   s = s<<7;
983   s |= b;
984   /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
985 
986   p++;
987   b = b<<14;
988   b |= *p;
989   /* b: p1<<28 | p3<<14 | p5 (unmasked) */
990   if (!(b&0x80))
991   {
992     /* we can skip this cause it was (effectively) done above in calc'ing s */
993     /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
994     a &= SLOT_2_0;
995     a = a<<7;
996     a |= b;
997     s = s>>18;
998     *v = ((u64)s)<<32 | a;
999     return 6;
1000   }
1001 
1002   p++;
1003   a = a<<14;
1004   a |= *p;
1005   /* a: p2<<28 | p4<<14 | p6 (unmasked) */
1006   if (!(a&0x80))
1007   {
1008     a &= SLOT_4_2_0;
1009     b &= SLOT_2_0;
1010     b = b<<7;
1011     a |= b;
1012     s = s>>11;
1013     *v = ((u64)s)<<32 | a;
1014     return 7;
1015   }
1016 
1017   /* CSE2 from below */
1018   a &= SLOT_2_0;
1019   p++;
1020   b = b<<14;
1021   b |= *p;
1022   /* b: p3<<28 | p5<<14 | p7 (unmasked) */
1023   if (!(b&0x80))
1024   {
1025     b &= SLOT_4_2_0;
1026     /* moved CSE2 up */
1027     /* a &= (0x7f<<14)|(0x7f); */
1028     a = a<<7;
1029     a |= b;
1030     s = s>>4;
1031     *v = ((u64)s)<<32 | a;
1032     return 8;
1033   }
1034 
1035   p++;
1036   a = a<<15;
1037   a |= *p;
1038   /* a: p4<<29 | p6<<15 | p8 (unmasked) */
1039 
1040   /* moved CSE2 up */
1041   /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
1042   b &= SLOT_2_0;
1043   b = b<<8;
1044   a |= b;
1045 
1046   s = s<<4;
1047   b = p[-4];
1048   b &= 0x7f;
1049   b = b>>3;
1050   s |= b;
1051 
1052   *v = ((u64)s)<<32 | a;
1053 
1054   return 9;
1055 }
1056 
1057 /*
1058 ** Read a 32-bit variable-length integer from memory starting at p[0].
1059 ** Return the number of bytes read.  The value is stored in *v.
1060 **
1061 ** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
1062 ** integer, then set *v to 0xffffffff.
1063 **
1064 ** A MACRO version, getVarint32, is provided which inlines the
1065 ** single-byte case.  All code should use the MACRO version as
1066 ** this function assumes the single-byte case has already been handled.
1067 */
1068 u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
1069   u32 a,b;
1070 
1071   /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
1072   ** by the getVarin32() macro */
1073   a = *p;
1074   /* a: p0 (unmasked) */
1075 #ifndef getVarint32
1076   if (!(a&0x80))
1077   {
1078     /* Values between 0 and 127 */
1079     *v = a;
1080     return 1;
1081   }
1082 #endif
1083 
1084   /* The 2-byte case */
1085   p++;
1086   b = *p;
1087   /* b: p1 (unmasked) */
1088   if (!(b&0x80))
1089   {
1090     /* Values between 128 and 16383 */
1091     a &= 0x7f;
1092     a = a<<7;
1093     *v = a | b;
1094     return 2;
1095   }
1096 
1097   /* The 3-byte case */
1098   p++;
1099   a = a<<14;
1100   a |= *p;
1101   /* a: p0<<14 | p2 (unmasked) */
1102   if (!(a&0x80))
1103   {
1104     /* Values between 16384 and 2097151 */
1105     a &= (0x7f<<14)|(0x7f);
1106     b &= 0x7f;
1107     b = b<<7;
1108     *v = a | b;
1109     return 3;
1110   }
1111 
1112   /* A 32-bit varint is used to store size information in btrees.
1113   ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
1114   ** A 3-byte varint is sufficient, for example, to record the size
1115   ** of a 1048569-byte BLOB or string.
1116   **
1117   ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
1118   ** rare larger cases can be handled by the slower 64-bit varint
1119   ** routine.
1120   */
1121 #if 1
1122   {
1123     u64 v64;
1124     u8 n;
1125 
1126     p -= 2;
1127     n = sqlite3GetVarint(p, &v64);
1128     assert( n>3 && n<=9 );
1129     if( (v64 & SQLITE_MAX_U32)!=v64 ){
1130       *v = 0xffffffff;
1131     }else{
1132       *v = (u32)v64;
1133     }
1134     return n;
1135   }
1136 
1137 #else
1138   /* For following code (kept for historical record only) shows an
1139   ** unrolling for the 3- and 4-byte varint cases.  This code is
1140   ** slightly faster, but it is also larger and much harder to test.
1141   */
1142   p++;
1143   b = b<<14;
1144   b |= *p;
1145   /* b: p1<<14 | p3 (unmasked) */
1146   if (!(b&0x80))
1147   {
1148     /* Values between 2097152 and 268435455 */
1149     b &= (0x7f<<14)|(0x7f);
1150     a &= (0x7f<<14)|(0x7f);
1151     a = a<<7;
1152     *v = a | b;
1153     return 4;
1154   }
1155 
1156   p++;
1157   a = a<<14;
1158   a |= *p;
1159   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
1160   if (!(a&0x80))
1161   {
1162     /* Values  between 268435456 and 34359738367 */
1163     a &= SLOT_4_2_0;
1164     b &= SLOT_4_2_0;
1165     b = b<<7;
1166     *v = a | b;
1167     return 5;
1168   }
1169 
1170   /* We can only reach this point when reading a corrupt database
1171   ** file.  In that case we are not in any hurry.  Use the (relatively
1172   ** slow) general-purpose sqlite3GetVarint() routine to extract the
1173   ** value. */
1174   {
1175     u64 v64;
1176     u8 n;
1177 
1178     p -= 4;
1179     n = sqlite3GetVarint(p, &v64);
1180     assert( n>5 && n<=9 );
1181     *v = (u32)v64;
1182     return n;
1183   }
1184 #endif
1185 }
1186 
1187 /*
1188 ** Return the number of bytes that will be needed to store the given
1189 ** 64-bit integer.
1190 */
1191 int sqlite3VarintLen(u64 v){
1192   int i;
1193   for(i=1; (v >>= 7)!=0; i++){ assert( i<10 ); }
1194   return i;
1195 }
1196 
1197 
1198 /*
1199 ** Read or write a four-byte big-endian integer value.
1200 */
1201 u32 sqlite3Get4byte(const u8 *p){
1202 #if SQLITE_BYTEORDER==4321
1203   u32 x;
1204   memcpy(&x,p,4);
1205   return x;
1206 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1207   u32 x;
1208   memcpy(&x,p,4);
1209   return __builtin_bswap32(x);
1210 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1211   u32 x;
1212   memcpy(&x,p,4);
1213   return _byteswap_ulong(x);
1214 #else
1215   testcase( p[0]&0x80 );
1216   return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
1217 #endif
1218 }
1219 void sqlite3Put4byte(unsigned char *p, u32 v){
1220 #if SQLITE_BYTEORDER==4321
1221   memcpy(p,&v,4);
1222 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1223   u32 x = __builtin_bswap32(v);
1224   memcpy(p,&x,4);
1225 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1226   u32 x = _byteswap_ulong(v);
1227   memcpy(p,&x,4);
1228 #else
1229   p[0] = (u8)(v>>24);
1230   p[1] = (u8)(v>>16);
1231   p[2] = (u8)(v>>8);
1232   p[3] = (u8)v;
1233 #endif
1234 }
1235 
1236 
1237 
1238 /*
1239 ** Translate a single byte of Hex into an integer.
1240 ** This routine only works if h really is a valid hexadecimal
1241 ** character:  0..9a..fA..F
1242 */
1243 u8 sqlite3HexToInt(int h){
1244   assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
1245 #ifdef SQLITE_ASCII
1246   h += 9*(1&(h>>6));
1247 #endif
1248 #ifdef SQLITE_EBCDIC
1249   h += 9*(1&~(h>>4));
1250 #endif
1251   return (u8)(h & 0xf);
1252 }
1253 
1254 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
1255 /*
1256 ** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
1257 ** value.  Return a pointer to its binary value.  Space to hold the
1258 ** binary value has been obtained from malloc and must be freed by
1259 ** the calling routine.
1260 */
1261 void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
1262   char *zBlob;
1263   int i;
1264 
1265   zBlob = (char *)sqlite3DbMallocRawNN(db, n/2 + 1);
1266   n--;
1267   if( zBlob ){
1268     for(i=0; i<n; i+=2){
1269       zBlob[i/2] = (sqlite3HexToInt(z[i])<<4) | sqlite3HexToInt(z[i+1]);
1270     }
1271     zBlob[i/2] = 0;
1272   }
1273   return zBlob;
1274 }
1275 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
1276 
1277 /*
1278 ** Log an error that is an API call on a connection pointer that should
1279 ** not have been used.  The "type" of connection pointer is given as the
1280 ** argument.  The zType is a word like "NULL" or "closed" or "invalid".
1281 */
1282 static void logBadConnection(const char *zType){
1283   sqlite3_log(SQLITE_MISUSE,
1284      "API call with %s database connection pointer",
1285      zType
1286   );
1287 }
1288 
1289 /*
1290 ** Check to make sure we have a valid db pointer.  This test is not
1291 ** foolproof but it does provide some measure of protection against
1292 ** misuse of the interface such as passing in db pointers that are
1293 ** NULL or which have been previously closed.  If this routine returns
1294 ** 1 it means that the db pointer is valid and 0 if it should not be
1295 ** dereferenced for any reason.  The calling function should invoke
1296 ** SQLITE_MISUSE immediately.
1297 **
1298 ** sqlite3SafetyCheckOk() requires that the db pointer be valid for
1299 ** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
1300 ** open properly and is not fit for general use but which can be
1301 ** used as an argument to sqlite3_errmsg() or sqlite3_close().
1302 */
1303 int sqlite3SafetyCheckOk(sqlite3 *db){
1304   u32 magic;
1305   if( db==0 ){
1306     logBadConnection("NULL");
1307     return 0;
1308   }
1309   magic = db->magic;
1310   if( magic!=SQLITE_MAGIC_OPEN ){
1311     if( sqlite3SafetyCheckSickOrOk(db) ){
1312       testcase( sqlite3GlobalConfig.xLog!=0 );
1313       logBadConnection("unopened");
1314     }
1315     return 0;
1316   }else{
1317     return 1;
1318   }
1319 }
1320 int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
1321   u32 magic;
1322   magic = db->magic;
1323   if( magic!=SQLITE_MAGIC_SICK &&
1324       magic!=SQLITE_MAGIC_OPEN &&
1325       magic!=SQLITE_MAGIC_BUSY ){
1326     testcase( sqlite3GlobalConfig.xLog!=0 );
1327     logBadConnection("invalid");
1328     return 0;
1329   }else{
1330     return 1;
1331   }
1332 }
1333 
1334 /*
1335 ** Attempt to add, substract, or multiply the 64-bit signed value iB against
1336 ** the other 64-bit signed integer at *pA and store the result in *pA.
1337 ** Return 0 on success.  Or if the operation would have resulted in an
1338 ** overflow, leave *pA unchanged and return 1.
1339 */
1340 int sqlite3AddInt64(i64 *pA, i64 iB){
1341 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1342   return __builtin_add_overflow(*pA, iB, pA);
1343 #else
1344   i64 iA = *pA;
1345   testcase( iA==0 ); testcase( iA==1 );
1346   testcase( iB==-1 ); testcase( iB==0 );
1347   if( iB>=0 ){
1348     testcase( iA>0 && LARGEST_INT64 - iA == iB );
1349     testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
1350     if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
1351   }else{
1352     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
1353     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
1354     if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
1355   }
1356   *pA += iB;
1357   return 0;
1358 #endif
1359 }
1360 int sqlite3SubInt64(i64 *pA, i64 iB){
1361 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1362   return __builtin_sub_overflow(*pA, iB, pA);
1363 #else
1364   testcase( iB==SMALLEST_INT64+1 );
1365   if( iB==SMALLEST_INT64 ){
1366     testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
1367     if( (*pA)>=0 ) return 1;
1368     *pA -= iB;
1369     return 0;
1370   }else{
1371     return sqlite3AddInt64(pA, -iB);
1372   }
1373 #endif
1374 }
1375 int sqlite3MulInt64(i64 *pA, i64 iB){
1376 #if GCC_VERSION>=5004000 && !defined(__INTEL_COMPILER)
1377   return __builtin_mul_overflow(*pA, iB, pA);
1378 #else
1379   i64 iA = *pA;
1380   if( iB>0 ){
1381     if( iA>LARGEST_INT64/iB ) return 1;
1382     if( iA<SMALLEST_INT64/iB ) return 1;
1383   }else if( iB<0 ){
1384     if( iA>0 ){
1385       if( iB<SMALLEST_INT64/iA ) return 1;
1386     }else if( iA<0 ){
1387       if( iB==SMALLEST_INT64 ) return 1;
1388       if( iA==SMALLEST_INT64 ) return 1;
1389       if( -iA>LARGEST_INT64/-iB ) return 1;
1390     }
1391   }
1392   *pA = iA*iB;
1393   return 0;
1394 #endif
1395 }
1396 
1397 /*
1398 ** Compute the absolute value of a 32-bit signed integer, of possible.  Or
1399 ** if the integer has a value of -2147483648, return +2147483647
1400 */
1401 int sqlite3AbsInt32(int x){
1402   if( x>=0 ) return x;
1403   if( x==(int)0x80000000 ) return 0x7fffffff;
1404   return -x;
1405 }
1406 
1407 #ifdef SQLITE_ENABLE_8_3_NAMES
1408 /*
1409 ** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
1410 ** filename in zBaseFilename is a URI with the "8_3_names=1" parameter and
1411 ** if filename in z[] has a suffix (a.k.a. "extension") that is longer than
1412 ** three characters, then shorten the suffix on z[] to be the last three
1413 ** characters of the original suffix.
1414 **
1415 ** If SQLITE_ENABLE_8_3_NAMES is set to 2 at compile-time, then always
1416 ** do the suffix shortening regardless of URI parameter.
1417 **
1418 ** Examples:
1419 **
1420 **     test.db-journal    =>   test.nal
1421 **     test.db-wal        =>   test.wal
1422 **     test.db-shm        =>   test.shm
1423 **     test.db-mj7f3319fa =>   test.9fa
1424 */
1425 void sqlite3FileSuffix3(const char *zBaseFilename, char *z){
1426 #if SQLITE_ENABLE_8_3_NAMES<2
1427   if( sqlite3_uri_boolean(zBaseFilename, "8_3_names", 0) )
1428 #endif
1429   {
1430     int i, sz;
1431     sz = sqlite3Strlen30(z);
1432     for(i=sz-1; i>0 && z[i]!='/' && z[i]!='.'; i--){}
1433     if( z[i]=='.' && ALWAYS(sz>i+4) ) memmove(&z[i+1], &z[sz-3], 4);
1434   }
1435 }
1436 #endif
1437 
1438 /*
1439 ** Find (an approximate) sum of two LogEst values.  This computation is
1440 ** not a simple "+" operator because LogEst is stored as a logarithmic
1441 ** value.
1442 **
1443 */
1444 LogEst sqlite3LogEstAdd(LogEst a, LogEst b){
1445   static const unsigned char x[] = {
1446      10, 10,                         /* 0,1 */
1447       9, 9,                          /* 2,3 */
1448       8, 8,                          /* 4,5 */
1449       7, 7, 7,                       /* 6,7,8 */
1450       6, 6, 6,                       /* 9,10,11 */
1451       5, 5, 5,                       /* 12-14 */
1452       4, 4, 4, 4,                    /* 15-18 */
1453       3, 3, 3, 3, 3, 3,              /* 19-24 */
1454       2, 2, 2, 2, 2, 2, 2,           /* 25-31 */
1455   };
1456   if( a>=b ){
1457     if( a>b+49 ) return a;
1458     if( a>b+31 ) return a+1;
1459     return a+x[a-b];
1460   }else{
1461     if( b>a+49 ) return b;
1462     if( b>a+31 ) return b+1;
1463     return b+x[b-a];
1464   }
1465 }
1466 
1467 /*
1468 ** Convert an integer into a LogEst.  In other words, compute an
1469 ** approximation for 10*log2(x).
1470 */
1471 LogEst sqlite3LogEst(u64 x){
1472   static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 };
1473   LogEst y = 40;
1474   if( x<8 ){
1475     if( x<2 ) return 0;
1476     while( x<8 ){  y -= 10; x <<= 1; }
1477   }else{
1478 #if GCC_VERSION>=5004000
1479     int i = 60 - __builtin_clzll(x);
1480     y += i*10;
1481     x >>= i;
1482 #else
1483     while( x>255 ){ y += 40; x >>= 4; }  /*OPTIMIZATION-IF-TRUE*/
1484     while( x>15 ){  y += 10; x >>= 1; }
1485 #endif
1486   }
1487   return a[x&7] + y - 10;
1488 }
1489 
1490 #ifndef SQLITE_OMIT_VIRTUALTABLE
1491 /*
1492 ** Convert a double into a LogEst
1493 ** In other words, compute an approximation for 10*log2(x).
1494 */
1495 LogEst sqlite3LogEstFromDouble(double x){
1496   u64 a;
1497   LogEst e;
1498   assert( sizeof(x)==8 && sizeof(a)==8 );
1499   if( x<=1 ) return 0;
1500   if( x<=2000000000 ) return sqlite3LogEst((u64)x);
1501   memcpy(&a, &x, 8);
1502   e = (a>>52) - 1022;
1503   return e*10;
1504 }
1505 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1506 
1507 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1508     defined(SQLITE_ENABLE_STAT4) || \
1509     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1510 /*
1511 ** Convert a LogEst into an integer.
1512 **
1513 ** Note that this routine is only used when one or more of various
1514 ** non-standard compile-time options is enabled.
1515 */
1516 u64 sqlite3LogEstToInt(LogEst x){
1517   u64 n;
1518   n = x%10;
1519   x /= 10;
1520   if( n>=5 ) n -= 2;
1521   else if( n>=1 ) n -= 1;
1522 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1523     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1524   if( x>60 ) return (u64)LARGEST_INT64;
1525 #else
1526   /* If only SQLITE_ENABLE_STAT4 is on, then the largest input
1527   ** possible to this routine is 310, resulting in a maximum x of 31 */
1528   assert( x<=60 );
1529 #endif
1530   return x>=3 ? (n+8)<<(x-3) : (n+8)>>(3-x);
1531 }
1532 #endif /* defined SCANSTAT or STAT4 or ESTIMATED_ROWS */
1533 
1534 /*
1535 ** Add a new name/number pair to a VList.  This might require that the
1536 ** VList object be reallocated, so return the new VList.  If an OOM
1537 ** error occurs, the original VList returned and the
1538 ** db->mallocFailed flag is set.
1539 **
1540 ** A VList is really just an array of integers.  To destroy a VList,
1541 ** simply pass it to sqlite3DbFree().
1542 **
1543 ** The first integer is the number of integers allocated for the whole
1544 ** VList.  The second integer is the number of integers actually used.
1545 ** Each name/number pair is encoded by subsequent groups of 3 or more
1546 ** integers.
1547 **
1548 ** Each name/number pair starts with two integers which are the numeric
1549 ** value for the pair and the size of the name/number pair, respectively.
1550 ** The text name overlays one or more following integers.  The text name
1551 ** is always zero-terminated.
1552 **
1553 ** Conceptually:
1554 **
1555 **    struct VList {
1556 **      int nAlloc;   // Number of allocated slots
1557 **      int nUsed;    // Number of used slots
1558 **      struct VListEntry {
1559 **        int iValue;    // Value for this entry
1560 **        int nSlot;     // Slots used by this entry
1561 **        // ... variable name goes here
1562 **      } a[0];
1563 **    }
1564 **
1565 ** During code generation, pointers to the variable names within the
1566 ** VList are taken.  When that happens, nAlloc is set to zero as an
1567 ** indication that the VList may never again be enlarged, since the
1568 ** accompanying realloc() would invalidate the pointers.
1569 */
1570 VList *sqlite3VListAdd(
1571   sqlite3 *db,           /* The database connection used for malloc() */
1572   VList *pIn,            /* The input VList.  Might be NULL */
1573   const char *zName,     /* Name of symbol to add */
1574   int nName,             /* Bytes of text in zName */
1575   int iVal               /* Value to associate with zName */
1576 ){
1577   int nInt;              /* number of sizeof(int) objects needed for zName */
1578   char *z;               /* Pointer to where zName will be stored */
1579   int i;                 /* Index in pIn[] where zName is stored */
1580 
1581   nInt = nName/4 + 3;
1582   assert( pIn==0 || pIn[0]>=3 );  /* Verify ok to add new elements */
1583   if( pIn==0 || pIn[1]+nInt > pIn[0] ){
1584     /* Enlarge the allocation */
1585     sqlite3_int64 nAlloc = (pIn ? 2*(sqlite3_int64)pIn[0] : 10) + nInt;
1586     VList *pOut = sqlite3DbRealloc(db, pIn, nAlloc*sizeof(int));
1587     if( pOut==0 ) return pIn;
1588     if( pIn==0 ) pOut[1] = 2;
1589     pIn = pOut;
1590     pIn[0] = nAlloc;
1591   }
1592   i = pIn[1];
1593   pIn[i] = iVal;
1594   pIn[i+1] = nInt;
1595   z = (char*)&pIn[i+2];
1596   pIn[1] = i+nInt;
1597   assert( pIn[1]<=pIn[0] );
1598   memcpy(z, zName, nName);
1599   z[nName] = 0;
1600   return pIn;
1601 }
1602 
1603 /*
1604 ** Return a pointer to the name of a variable in the given VList that
1605 ** has the value iVal.  Or return a NULL if there is no such variable in
1606 ** the list
1607 */
1608 const char *sqlite3VListNumToName(VList *pIn, int iVal){
1609   int i, mx;
1610   if( pIn==0 ) return 0;
1611   mx = pIn[1];
1612   i = 2;
1613   do{
1614     if( pIn[i]==iVal ) return (char*)&pIn[i+2];
1615     i += pIn[i+1];
1616   }while( i<mx );
1617   return 0;
1618 }
1619 
1620 /*
1621 ** Return the number of the variable named zName, if it is in VList.
1622 ** or return 0 if there is no such variable.
1623 */
1624 int sqlite3VListNameToNum(VList *pIn, const char *zName, int nName){
1625   int i, mx;
1626   if( pIn==0 ) return 0;
1627   mx = pIn[1];
1628   i = 2;
1629   do{
1630     const char *z = (const char*)&pIn[i+2];
1631     if( strncmp(z,zName,nName)==0 && z[nName]==0 ) return pIn[i];
1632     i += pIn[i+1];
1633   }while( i<mx );
1634   return 0;
1635 }
1636