xref: /sqlite-3.40.0/src/util.c (revision c5e56b34)
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 #if HAVE_ISNAN || SQLITE_HAVE_ISNAN
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 ** Give a callback to the test harness that can be used to simulate faults
36 ** in places where it is difficult or expensive to do so purely by means
37 ** of inputs.
38 **
39 ** The intent of the integer argument is to let the fault simulator know
40 ** which of multiple sqlite3FaultSim() calls has been hit.
41 **
42 ** Return whatever integer value the test callback returns, or return
43 ** SQLITE_OK if no test callback is installed.
44 */
45 #ifndef SQLITE_UNTESTABLE
46 int sqlite3FaultSim(int iTest){
47   int (*xCallback)(int) = sqlite3GlobalConfig.xTestCallback;
48   return xCallback ? xCallback(iTest) : SQLITE_OK;
49 }
50 #endif
51 
52 #ifndef SQLITE_OMIT_FLOATING_POINT
53 /*
54 ** Return true if the floating point value is Not a Number (NaN).
55 **
56 ** Use the math library isnan() function if compiled with SQLITE_HAVE_ISNAN.
57 ** Otherwise, we have our own implementation that works on most systems.
58 */
59 int sqlite3IsNaN(double x){
60   int rc;   /* The value return */
61 #if !SQLITE_HAVE_ISNAN && !HAVE_ISNAN
62   /*
63   ** Systems that support the isnan() library function should probably
64   ** make use of it by compiling with -DSQLITE_HAVE_ISNAN.  But we have
65   ** found that many systems do not have a working isnan() function so
66   ** this implementation is provided as an alternative.
67   **
68   ** This NaN test sometimes fails if compiled on GCC with -ffast-math.
69   ** On the other hand, the use of -ffast-math comes with the following
70   ** warning:
71   **
72   **      This option [-ffast-math] should never be turned on by any
73   **      -O option since it can result in incorrect output for programs
74   **      which depend on an exact implementation of IEEE or ISO
75   **      rules/specifications for math functions.
76   **
77   ** Under MSVC, this NaN test may fail if compiled with a floating-
78   ** point precision mode other than /fp:precise.  From the MSDN
79   ** documentation:
80   **
81   **      The compiler [with /fp:precise] will properly handle comparisons
82   **      involving NaN. For example, x != x evaluates to true if x is NaN
83   **      ...
84   */
85 #ifdef __FAST_MATH__
86 # error SQLite will not work correctly with the -ffast-math option of GCC.
87 #endif
88   volatile double y = x;
89   volatile double z = y;
90   rc = (y!=z);
91 #else  /* if HAVE_ISNAN */
92   rc = isnan(x);
93 #endif /* HAVE_ISNAN */
94   testcase( rc );
95   return rc;
96 }
97 #endif /* SQLITE_OMIT_FLOATING_POINT */
98 
99 /*
100 ** Compute a string length that is limited to what can be stored in
101 ** lower 30 bits of a 32-bit signed integer.
102 **
103 ** The value returned will never be negative.  Nor will it ever be greater
104 ** than the actual length of the string.  For very long strings (greater
105 ** than 1GiB) the value returned might be less than the true string length.
106 */
107 int sqlite3Strlen30(const char *z){
108   if( z==0 ) return 0;
109   return 0x3fffffff & (int)strlen(z);
110 }
111 
112 /*
113 ** Return the declared type of a column.  Or return zDflt if the column
114 ** has no declared type.
115 **
116 ** The column type is an extra string stored after the zero-terminator on
117 ** the column name if and only if the COLFLAG_HASTYPE flag is set.
118 */
119 char *sqlite3ColumnType(Column *pCol, char *zDflt){
120   if( (pCol->colFlags & COLFLAG_HASTYPE)==0 ) return zDflt;
121   return pCol->zName + strlen(pCol->zName) + 1;
122 }
123 
124 /*
125 ** Helper function for sqlite3Error() - called rarely.  Broken out into
126 ** a separate routine to avoid unnecessary register saves on entry to
127 ** sqlite3Error().
128 */
129 static SQLITE_NOINLINE void  sqlite3ErrorFinish(sqlite3 *db, int err_code){
130   if( db->pErr ) sqlite3ValueSetNull(db->pErr);
131   sqlite3SystemError(db, err_code);
132 }
133 
134 /*
135 ** Set the current error code to err_code and clear any prior error message.
136 ** Also set iSysErrno (by calling sqlite3System) if the err_code indicates
137 ** that would be appropriate.
138 */
139 void sqlite3Error(sqlite3 *db, int err_code){
140   assert( db!=0 );
141   db->errCode = err_code;
142   if( err_code || db->pErr ) sqlite3ErrorFinish(db, err_code);
143 }
144 
145 /*
146 ** Load the sqlite3.iSysErrno field if that is an appropriate thing
147 ** to do based on the SQLite error code in rc.
148 */
149 void sqlite3SystemError(sqlite3 *db, int rc){
150   if( rc==SQLITE_IOERR_NOMEM ) return;
151   rc &= 0xff;
152   if( rc==SQLITE_CANTOPEN || rc==SQLITE_IOERR ){
153     db->iSysErrno = sqlite3OsGetLastError(db->pVfs);
154   }
155 }
156 
157 /*
158 ** Set the most recent error code and error string for the sqlite
159 ** handle "db". The error code is set to "err_code".
160 **
161 ** If it is not NULL, string zFormat specifies the format of the
162 ** error string in the style of the printf functions: The following
163 ** format characters are allowed:
164 **
165 **      %s      Insert a string
166 **      %z      A string that should be freed after use
167 **      %d      Insert an integer
168 **      %T      Insert a token
169 **      %S      Insert the first element of a SrcList
170 **
171 ** zFormat and any string tokens that follow it are assumed to be
172 ** encoded in UTF-8.
173 **
174 ** To clear the most recent error for sqlite handle "db", sqlite3Error
175 ** should be called with err_code set to SQLITE_OK and zFormat set
176 ** to NULL.
177 */
178 void sqlite3ErrorWithMsg(sqlite3 *db, int err_code, const char *zFormat, ...){
179   assert( db!=0 );
180   db->errCode = err_code;
181   sqlite3SystemError(db, err_code);
182   if( zFormat==0 ){
183     sqlite3Error(db, err_code);
184   }else if( db->pErr || (db->pErr = sqlite3ValueNew(db))!=0 ){
185     char *z;
186     va_list ap;
187     va_start(ap, zFormat);
188     z = sqlite3VMPrintf(db, zFormat, ap);
189     va_end(ap);
190     sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
191   }
192 }
193 
194 /*
195 ** Add an error message to pParse->zErrMsg and increment pParse->nErr.
196 ** The following formatting characters are allowed:
197 **
198 **      %s      Insert a string
199 **      %z      A string that should be freed after use
200 **      %d      Insert an integer
201 **      %T      Insert a token
202 **      %S      Insert the first element of a SrcList
203 **
204 ** This function should be used to report any error that occurs while
205 ** compiling an SQL statement (i.e. within sqlite3_prepare()). The
206 ** last thing the sqlite3_prepare() function does is copy the error
207 ** stored by this function into the database handle using sqlite3Error().
208 ** Functions sqlite3Error() or sqlite3ErrorWithMsg() should be used
209 ** during statement execution (sqlite3_step() etc.).
210 */
211 void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
212   char *zMsg;
213   va_list ap;
214   sqlite3 *db = pParse->db;
215   va_start(ap, zFormat);
216   zMsg = sqlite3VMPrintf(db, zFormat, ap);
217   va_end(ap);
218   if( db->suppressErr ){
219     sqlite3DbFree(db, zMsg);
220   }else{
221     pParse->nErr++;
222     sqlite3DbFree(db, pParse->zErrMsg);
223     pParse->zErrMsg = zMsg;
224     pParse->rc = SQLITE_ERROR;
225   }
226 }
227 
228 /*
229 ** Convert an SQL-style quoted string into a normal string by removing
230 ** the quote characters.  The conversion is done in-place.  If the
231 ** input does not begin with a quote character, then this routine
232 ** is a no-op.
233 **
234 ** The input string must be zero-terminated.  A new zero-terminator
235 ** is added to the dequoted string.
236 **
237 ** The return value is -1 if no dequoting occurs or the length of the
238 ** dequoted string, exclusive of the zero terminator, if dequoting does
239 ** occur.
240 **
241 ** 2002-Feb-14: This routine is extended to remove MS-Access style
242 ** brackets from around identifiers.  For example:  "[a-b-c]" becomes
243 ** "a-b-c".
244 */
245 void sqlite3Dequote(char *z){
246   char quote;
247   int i, j;
248   if( z==0 ) return;
249   quote = z[0];
250   if( !sqlite3Isquote(quote) ) return;
251   if( quote=='[' ) quote = ']';
252   for(i=1, j=0;; i++){
253     assert( z[i] );
254     if( z[i]==quote ){
255       if( z[i+1]==quote ){
256         z[j++] = quote;
257         i++;
258       }else{
259         break;
260       }
261     }else{
262       z[j++] = z[i];
263     }
264   }
265   z[j] = 0;
266 }
267 
268 /*
269 ** Generate a Token object from a string
270 */
271 void sqlite3TokenInit(Token *p, char *z){
272   p->z = z;
273   p->n = sqlite3Strlen30(z);
274 }
275 
276 /* Convenient short-hand */
277 #define UpperToLower sqlite3UpperToLower
278 
279 /*
280 ** Some systems have stricmp().  Others have strcasecmp().  Because
281 ** there is no consistency, we will define our own.
282 **
283 ** IMPLEMENTATION-OF: R-30243-02494 The sqlite3_stricmp() and
284 ** sqlite3_strnicmp() APIs allow applications and extensions to compare
285 ** the contents of two buffers containing UTF-8 strings in a
286 ** case-independent fashion, using the same definition of "case
287 ** independence" that SQLite uses internally when comparing identifiers.
288 */
289 int sqlite3_stricmp(const char *zLeft, const char *zRight){
290   if( zLeft==0 ){
291     return zRight ? -1 : 0;
292   }else if( zRight==0 ){
293     return 1;
294   }
295   return sqlite3StrICmp(zLeft, zRight);
296 }
297 int sqlite3StrICmp(const char *zLeft, const char *zRight){
298   unsigned char *a, *b;
299   int c;
300   a = (unsigned char *)zLeft;
301   b = (unsigned char *)zRight;
302   for(;;){
303     c = (int)UpperToLower[*a] - (int)UpperToLower[*b];
304     if( c || *a==0 ) break;
305     a++;
306     b++;
307   }
308   return c;
309 }
310 int sqlite3_strnicmp(const char *zLeft, const char *zRight, int N){
311   register unsigned char *a, *b;
312   if( zLeft==0 ){
313     return zRight ? -1 : 0;
314   }else if( zRight==0 ){
315     return 1;
316   }
317   a = (unsigned char *)zLeft;
318   b = (unsigned char *)zRight;
319   while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
320   return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
321 }
322 
323 /*
324 ** The string z[] is an text representation of a real number.
325 ** Convert this string to a double and write it into *pResult.
326 **
327 ** The string z[] is length bytes in length (bytes, not characters) and
328 ** uses the encoding enc.  The string is not necessarily zero-terminated.
329 **
330 ** Return TRUE if the result is a valid real number (or integer) and FALSE
331 ** if the string is empty or contains extraneous text.  Valid numbers
332 ** are in one of these formats:
333 **
334 **    [+-]digits[E[+-]digits]
335 **    [+-]digits.[digits][E[+-]digits]
336 **    [+-].digits[E[+-]digits]
337 **
338 ** Leading and trailing whitespace is ignored for the purpose of determining
339 ** validity.
340 **
341 ** If some prefix of the input string is a valid number, this routine
342 ** returns FALSE but it still converts the prefix and writes the result
343 ** into *pResult.
344 */
345 int sqlite3AtoF(const char *z, double *pResult, int length, u8 enc){
346 #ifndef SQLITE_OMIT_FLOATING_POINT
347   int incr;
348   const char *zEnd = z + length;
349   /* sign * significand * (10 ^ (esign * exponent)) */
350   int sign = 1;    /* sign of significand */
351   i64 s = 0;       /* significand */
352   int d = 0;       /* adjust exponent for shifting decimal point */
353   int esign = 1;   /* sign of exponent */
354   int e = 0;       /* exponent */
355   int eValid = 1;  /* True exponent is either not used or is well-formed */
356   double result;
357   int nDigits = 0;
358   int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
359 
360   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
361   *pResult = 0.0;   /* Default return value, in case of an error */
362 
363   if( enc==SQLITE_UTF8 ){
364     incr = 1;
365   }else{
366     int i;
367     incr = 2;
368     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
369     for(i=3-enc; i<length && z[i]==0; i+=2){}
370     nonNum = i<length;
371     zEnd = &z[i^1];
372     z += (enc&1);
373   }
374 
375   /* skip leading spaces */
376   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
377   if( z>=zEnd ) return 0;
378 
379   /* get sign of significand */
380   if( *z=='-' ){
381     sign = -1;
382     z+=incr;
383   }else if( *z=='+' ){
384     z+=incr;
385   }
386 
387   /* copy max significant digits to significand */
388   while( z<zEnd && sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
389     s = s*10 + (*z - '0');
390     z+=incr, nDigits++;
391   }
392 
393   /* skip non-significant significand digits
394   ** (increase exponent by d to shift decimal left) */
395   while( z<zEnd && sqlite3Isdigit(*z) ) z+=incr, nDigits++, d++;
396   if( z>=zEnd ) goto do_atof_calc;
397 
398   /* if decimal point is present */
399   if( *z=='.' ){
400     z+=incr;
401     /* copy digits from after decimal to significand
402     ** (decrease exponent by d to shift decimal right) */
403     while( z<zEnd && sqlite3Isdigit(*z) ){
404       if( s<((LARGEST_INT64-9)/10) ){
405         s = s*10 + (*z - '0');
406         d--;
407       }
408       z+=incr, nDigits++;
409     }
410   }
411   if( z>=zEnd ) goto do_atof_calc;
412 
413   /* if exponent is present */
414   if( *z=='e' || *z=='E' ){
415     z+=incr;
416     eValid = 0;
417 
418     /* This branch is needed to avoid a (harmless) buffer overread.  The
419     ** special comment alerts the mutation tester that the correct answer
420     ** is obtained even if the branch is omitted */
421     if( z>=zEnd ) goto do_atof_calc;              /*PREVENTS-HARMLESS-OVERREAD*/
422 
423     /* get sign of exponent */
424     if( *z=='-' ){
425       esign = -1;
426       z+=incr;
427     }else if( *z=='+' ){
428       z+=incr;
429     }
430     /* copy digits to exponent */
431     while( z<zEnd && sqlite3Isdigit(*z) ){
432       e = e<10000 ? (e*10 + (*z - '0')) : 10000;
433       z+=incr;
434       eValid = 1;
435     }
436   }
437 
438   /* skip trailing spaces */
439   while( z<zEnd && sqlite3Isspace(*z) ) z+=incr;
440 
441 do_atof_calc:
442   /* adjust exponent by d, and update sign */
443   e = (e*esign) + d;
444   if( e<0 ) {
445     esign = -1;
446     e *= -1;
447   } else {
448     esign = 1;
449   }
450 
451   if( s==0 ) {
452     /* In the IEEE 754 standard, zero is signed. */
453     result = sign<0 ? -(double)0 : (double)0;
454   } else {
455     /* Attempt to reduce exponent.
456     **
457     ** Branches that are not required for the correct answer but which only
458     ** help to obtain the correct answer faster are marked with special
459     ** comments, as a hint to the mutation tester.
460     */
461     while( e>0 ){                                       /*OPTIMIZATION-IF-TRUE*/
462       if( esign>0 ){
463         if( s>=(LARGEST_INT64/10) ) break;             /*OPTIMIZATION-IF-FALSE*/
464         s *= 10;
465       }else{
466         if( s%10!=0 ) break;                           /*OPTIMIZATION-IF-FALSE*/
467         s /= 10;
468       }
469       e--;
470     }
471 
472     /* adjust the sign of significand */
473     s = sign<0 ? -s : s;
474 
475     if( e==0 ){                                         /*OPTIMIZATION-IF-TRUE*/
476       result = (double)s;
477     }else{
478       LONGDOUBLE_TYPE scale = 1.0;
479       /* attempt to handle extremely small/large numbers better */
480       if( e>307 ){                                      /*OPTIMIZATION-IF-TRUE*/
481         if( e<342 ){                                    /*OPTIMIZATION-IF-TRUE*/
482           while( e%308 ) { scale *= 1.0e+1; e -= 1; }
483           if( esign<0 ){
484             result = s / scale;
485             result /= 1.0e+308;
486           }else{
487             result = s * scale;
488             result *= 1.0e+308;
489           }
490         }else{ assert( e>=342 );
491           if( esign<0 ){
492             result = 0.0*s;
493           }else{
494             result = 1e308*1e308*s;  /* Infinity */
495           }
496         }
497       }else{
498         /* 1.0e+22 is the largest power of 10 than can be
499         ** represented exactly. */
500         while( e%22 ) { scale *= 1.0e+1; e -= 1; }
501         while( e>0 ) { scale *= 1.0e+22; e -= 22; }
502         if( esign<0 ){
503           result = s / scale;
504         }else{
505           result = s * scale;
506         }
507       }
508     }
509   }
510 
511   /* store the result */
512   *pResult = result;
513 
514   /* return true if number and no extra non-whitespace chracters after */
515   return z==zEnd && nDigits>0 && eValid && nonNum==0;
516 #else
517   return !sqlite3Atoi64(z, pResult, length, enc);
518 #endif /* SQLITE_OMIT_FLOATING_POINT */
519 }
520 
521 /*
522 ** Compare the 19-character string zNum against the text representation
523 ** value 2^63:  9223372036854775808.  Return negative, zero, or positive
524 ** if zNum is less than, equal to, or greater than the string.
525 ** Note that zNum must contain exactly 19 characters.
526 **
527 ** Unlike memcmp() this routine is guaranteed to return the difference
528 ** in the values of the last digit if the only difference is in the
529 ** last digit.  So, for example,
530 **
531 **      compare2pow63("9223372036854775800", 1)
532 **
533 ** will return -8.
534 */
535 static int compare2pow63(const char *zNum, int incr){
536   int c = 0;
537   int i;
538                     /* 012345678901234567 */
539   const char *pow63 = "922337203685477580";
540   for(i=0; c==0 && i<18; i++){
541     c = (zNum[i*incr]-pow63[i])*10;
542   }
543   if( c==0 ){
544     c = zNum[18*incr] - '8';
545     testcase( c==(-1) );
546     testcase( c==0 );
547     testcase( c==(+1) );
548   }
549   return c;
550 }
551 
552 /*
553 ** Convert zNum to a 64-bit signed integer.  zNum must be decimal. This
554 ** routine does *not* accept hexadecimal notation.
555 **
556 ** If the zNum value is representable as a 64-bit twos-complement
557 ** integer, then write that value into *pNum and return 0.
558 **
559 ** If zNum is exactly 9223372036854775808, return 2.  This special
560 ** case is broken out because while 9223372036854775808 cannot be a
561 ** signed 64-bit integer, its negative -9223372036854775808 can be.
562 **
563 ** If zNum is too big for a 64-bit integer and is not
564 ** 9223372036854775808  or if zNum contains any non-numeric text,
565 ** then return 1.
566 **
567 ** length is the number of bytes in the string (bytes, not characters).
568 ** The string is not necessarily zero-terminated.  The encoding is
569 ** given by enc.
570 */
571 int sqlite3Atoi64(const char *zNum, i64 *pNum, int length, u8 enc){
572   int incr;
573   u64 u = 0;
574   int neg = 0; /* assume positive */
575   int i;
576   int c = 0;
577   int nonNum = 0;  /* True if input contains UTF16 with high byte non-zero */
578   const char *zStart;
579   const char *zEnd = zNum + length;
580   assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
581   if( enc==SQLITE_UTF8 ){
582     incr = 1;
583   }else{
584     incr = 2;
585     assert( SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
586     for(i=3-enc; i<length && zNum[i]==0; i+=2){}
587     nonNum = i<length;
588     zEnd = &zNum[i^1];
589     zNum += (enc&1);
590   }
591   while( zNum<zEnd && sqlite3Isspace(*zNum) ) zNum+=incr;
592   if( zNum<zEnd ){
593     if( *zNum=='-' ){
594       neg = 1;
595       zNum+=incr;
596     }else if( *zNum=='+' ){
597       zNum+=incr;
598     }
599   }
600   zStart = zNum;
601   while( zNum<zEnd && zNum[0]=='0' ){ zNum+=incr; } /* Skip leading zeros. */
602   for(i=0; &zNum[i]<zEnd && (c=zNum[i])>='0' && c<='9'; i+=incr){
603     u = u*10 + c - '0';
604   }
605   if( u>LARGEST_INT64 ){
606     *pNum = neg ? SMALLEST_INT64 : LARGEST_INT64;
607   }else if( neg ){
608     *pNum = -(i64)u;
609   }else{
610     *pNum = (i64)u;
611   }
612   testcase( i==18 );
613   testcase( i==19 );
614   testcase( i==20 );
615   if( &zNum[i]<zEnd              /* Extra bytes at the end */
616    || (i==0 && zStart==zNum)     /* No digits */
617    || i>19*incr                  /* Too many digits */
618    || nonNum                     /* UTF16 with high-order bytes non-zero */
619   ){
620     /* zNum is empty or contains non-numeric text or is longer
621     ** than 19 digits (thus guaranteeing that it is too large) */
622     return 1;
623   }else if( i<19*incr ){
624     /* Less than 19 digits, so we know that it fits in 64 bits */
625     assert( u<=LARGEST_INT64 );
626     return 0;
627   }else{
628     /* zNum is a 19-digit numbers.  Compare it against 9223372036854775808. */
629     c = compare2pow63(zNum, incr);
630     if( c<0 ){
631       /* zNum is less than 9223372036854775808 so it fits */
632       assert( u<=LARGEST_INT64 );
633       return 0;
634     }else if( c>0 ){
635       /* zNum is greater than 9223372036854775808 so it overflows */
636       return 1;
637     }else{
638       /* zNum is exactly 9223372036854775808.  Fits if negative.  The
639       ** special case 2 overflow if positive */
640       assert( u-1==LARGEST_INT64 );
641       return neg ? 0 : 2;
642     }
643   }
644 }
645 
646 /*
647 ** Transform a UTF-8 integer literal, in either decimal or hexadecimal,
648 ** into a 64-bit signed integer.  This routine accepts hexadecimal literals,
649 ** whereas sqlite3Atoi64() does not.
650 **
651 ** Returns:
652 **
653 **     0    Successful transformation.  Fits in a 64-bit signed integer.
654 **     1    Integer too large for a 64-bit signed integer or is malformed
655 **     2    Special case of 9223372036854775808
656 */
657 int sqlite3DecOrHexToI64(const char *z, i64 *pOut){
658 #ifndef SQLITE_OMIT_HEX_INTEGER
659   if( z[0]=='0'
660    && (z[1]=='x' || z[1]=='X')
661   ){
662     u64 u = 0;
663     int i, k;
664     for(i=2; z[i]=='0'; i++){}
665     for(k=i; sqlite3Isxdigit(z[k]); k++){
666       u = u*16 + sqlite3HexToInt(z[k]);
667     }
668     memcpy(pOut, &u, 8);
669     return (z[k]==0 && k-i<=16) ? 0 : 1;
670   }else
671 #endif /* SQLITE_OMIT_HEX_INTEGER */
672   {
673     return sqlite3Atoi64(z, pOut, sqlite3Strlen30(z), SQLITE_UTF8);
674   }
675 }
676 
677 /*
678 ** If zNum represents an integer that will fit in 32-bits, then set
679 ** *pValue to that integer and return true.  Otherwise return false.
680 **
681 ** This routine accepts both decimal and hexadecimal notation for integers.
682 **
683 ** Any non-numeric characters that following zNum are ignored.
684 ** This is different from sqlite3Atoi64() which requires the
685 ** input number to be zero-terminated.
686 */
687 int sqlite3GetInt32(const char *zNum, int *pValue){
688   sqlite_int64 v = 0;
689   int i, c;
690   int neg = 0;
691   if( zNum[0]=='-' ){
692     neg = 1;
693     zNum++;
694   }else if( zNum[0]=='+' ){
695     zNum++;
696   }
697 #ifndef SQLITE_OMIT_HEX_INTEGER
698   else if( zNum[0]=='0'
699         && (zNum[1]=='x' || zNum[1]=='X')
700         && sqlite3Isxdigit(zNum[2])
701   ){
702     u32 u = 0;
703     zNum += 2;
704     while( zNum[0]=='0' ) zNum++;
705     for(i=0; sqlite3Isxdigit(zNum[i]) && i<8; i++){
706       u = u*16 + sqlite3HexToInt(zNum[i]);
707     }
708     if( (u&0x80000000)==0 && sqlite3Isxdigit(zNum[i])==0 ){
709       memcpy(pValue, &u, 4);
710       return 1;
711     }else{
712       return 0;
713     }
714   }
715 #endif
716   if( !sqlite3Isdigit(zNum[0]) ) return 0;
717   while( zNum[0]=='0' ) zNum++;
718   for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
719     v = v*10 + c;
720   }
721 
722   /* The longest decimal representation of a 32 bit integer is 10 digits:
723   **
724   **             1234567890
725   **     2^31 -> 2147483648
726   */
727   testcase( i==10 );
728   if( i>10 ){
729     return 0;
730   }
731   testcase( v-neg==2147483647 );
732   if( v-neg>2147483647 ){
733     return 0;
734   }
735   if( neg ){
736     v = -v;
737   }
738   *pValue = (int)v;
739   return 1;
740 }
741 
742 /*
743 ** Return a 32-bit integer value extracted from a string.  If the
744 ** string is not an integer, just return 0.
745 */
746 int sqlite3Atoi(const char *z){
747   int x = 0;
748   if( z ) sqlite3GetInt32(z, &x);
749   return x;
750 }
751 
752 /*
753 ** The variable-length integer encoding is as follows:
754 **
755 ** KEY:
756 **         A = 0xxxxxxx    7 bits of data and one flag bit
757 **         B = 1xxxxxxx    7 bits of data and one flag bit
758 **         C = xxxxxxxx    8 bits of data
759 **
760 **  7 bits - A
761 ** 14 bits - BA
762 ** 21 bits - BBA
763 ** 28 bits - BBBA
764 ** 35 bits - BBBBA
765 ** 42 bits - BBBBBA
766 ** 49 bits - BBBBBBA
767 ** 56 bits - BBBBBBBA
768 ** 64 bits - BBBBBBBBC
769 */
770 
771 /*
772 ** Write a 64-bit variable-length integer to memory starting at p[0].
773 ** The length of data write will be between 1 and 9 bytes.  The number
774 ** of bytes written is returned.
775 **
776 ** A variable-length integer consists of the lower 7 bits of each byte
777 ** for all bytes that have the 8th bit set and one byte with the 8th
778 ** bit clear.  Except, if we get to the 9th byte, it stores the full
779 ** 8 bits and is the last byte.
780 */
781 static int SQLITE_NOINLINE putVarint64(unsigned char *p, u64 v){
782   int i, j, n;
783   u8 buf[10];
784   if( v & (((u64)0xff000000)<<32) ){
785     p[8] = (u8)v;
786     v >>= 8;
787     for(i=7; i>=0; i--){
788       p[i] = (u8)((v & 0x7f) | 0x80);
789       v >>= 7;
790     }
791     return 9;
792   }
793   n = 0;
794   do{
795     buf[n++] = (u8)((v & 0x7f) | 0x80);
796     v >>= 7;
797   }while( v!=0 );
798   buf[0] &= 0x7f;
799   assert( n<=9 );
800   for(i=0, j=n-1; j>=0; j--, i++){
801     p[i] = buf[j];
802   }
803   return n;
804 }
805 int sqlite3PutVarint(unsigned char *p, u64 v){
806   if( v<=0x7f ){
807     p[0] = v&0x7f;
808     return 1;
809   }
810   if( v<=0x3fff ){
811     p[0] = ((v>>7)&0x7f)|0x80;
812     p[1] = v&0x7f;
813     return 2;
814   }
815   return putVarint64(p,v);
816 }
817 
818 /*
819 ** Bitmasks used by sqlite3GetVarint().  These precomputed constants
820 ** are defined here rather than simply putting the constant expressions
821 ** inline in order to work around bugs in the RVT compiler.
822 **
823 ** SLOT_2_0     A mask for  (0x7f<<14) | 0x7f
824 **
825 ** SLOT_4_2_0   A mask for  (0x7f<<28) | SLOT_2_0
826 */
827 #define SLOT_2_0     0x001fc07f
828 #define SLOT_4_2_0   0xf01fc07f
829 
830 
831 /*
832 ** Read a 64-bit variable-length integer from memory starting at p[0].
833 ** Return the number of bytes read.  The value is stored in *v.
834 */
835 u8 sqlite3GetVarint(const unsigned char *p, u64 *v){
836   u32 a,b,s;
837 
838   a = *p;
839   /* a: p0 (unmasked) */
840   if (!(a&0x80))
841   {
842     *v = a;
843     return 1;
844   }
845 
846   p++;
847   b = *p;
848   /* b: p1 (unmasked) */
849   if (!(b&0x80))
850   {
851     a &= 0x7f;
852     a = a<<7;
853     a |= b;
854     *v = a;
855     return 2;
856   }
857 
858   /* Verify that constants are precomputed correctly */
859   assert( SLOT_2_0 == ((0x7f<<14) | (0x7f)) );
860   assert( SLOT_4_2_0 == ((0xfU<<28) | (0x7f<<14) | (0x7f)) );
861 
862   p++;
863   a = a<<14;
864   a |= *p;
865   /* a: p0<<14 | p2 (unmasked) */
866   if (!(a&0x80))
867   {
868     a &= SLOT_2_0;
869     b &= 0x7f;
870     b = b<<7;
871     a |= b;
872     *v = a;
873     return 3;
874   }
875 
876   /* CSE1 from below */
877   a &= SLOT_2_0;
878   p++;
879   b = b<<14;
880   b |= *p;
881   /* b: p1<<14 | p3 (unmasked) */
882   if (!(b&0x80))
883   {
884     b &= SLOT_2_0;
885     /* moved CSE1 up */
886     /* a &= (0x7f<<14)|(0x7f); */
887     a = a<<7;
888     a |= b;
889     *v = a;
890     return 4;
891   }
892 
893   /* a: p0<<14 | p2 (masked) */
894   /* b: p1<<14 | p3 (unmasked) */
895   /* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
896   /* moved CSE1 up */
897   /* a &= (0x7f<<14)|(0x7f); */
898   b &= SLOT_2_0;
899   s = a;
900   /* s: p0<<14 | p2 (masked) */
901 
902   p++;
903   a = a<<14;
904   a |= *p;
905   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
906   if (!(a&0x80))
907   {
908     /* we can skip these cause they were (effectively) done above
909     ** while calculating s */
910     /* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
911     /* b &= (0x7f<<14)|(0x7f); */
912     b = b<<7;
913     a |= b;
914     s = s>>18;
915     *v = ((u64)s)<<32 | a;
916     return 5;
917   }
918 
919   /* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
920   s = s<<7;
921   s |= b;
922   /* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
923 
924   p++;
925   b = b<<14;
926   b |= *p;
927   /* b: p1<<28 | p3<<14 | p5 (unmasked) */
928   if (!(b&0x80))
929   {
930     /* we can skip this cause it was (effectively) done above in calc'ing s */
931     /* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
932     a &= SLOT_2_0;
933     a = a<<7;
934     a |= b;
935     s = s>>18;
936     *v = ((u64)s)<<32 | a;
937     return 6;
938   }
939 
940   p++;
941   a = a<<14;
942   a |= *p;
943   /* a: p2<<28 | p4<<14 | p6 (unmasked) */
944   if (!(a&0x80))
945   {
946     a &= SLOT_4_2_0;
947     b &= SLOT_2_0;
948     b = b<<7;
949     a |= b;
950     s = s>>11;
951     *v = ((u64)s)<<32 | a;
952     return 7;
953   }
954 
955   /* CSE2 from below */
956   a &= SLOT_2_0;
957   p++;
958   b = b<<14;
959   b |= *p;
960   /* b: p3<<28 | p5<<14 | p7 (unmasked) */
961   if (!(b&0x80))
962   {
963     b &= SLOT_4_2_0;
964     /* moved CSE2 up */
965     /* a &= (0x7f<<14)|(0x7f); */
966     a = a<<7;
967     a |= b;
968     s = s>>4;
969     *v = ((u64)s)<<32 | a;
970     return 8;
971   }
972 
973   p++;
974   a = a<<15;
975   a |= *p;
976   /* a: p4<<29 | p6<<15 | p8 (unmasked) */
977 
978   /* moved CSE2 up */
979   /* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
980   b &= SLOT_2_0;
981   b = b<<8;
982   a |= b;
983 
984   s = s<<4;
985   b = p[-4];
986   b &= 0x7f;
987   b = b>>3;
988   s |= b;
989 
990   *v = ((u64)s)<<32 | a;
991 
992   return 9;
993 }
994 
995 /*
996 ** Read a 32-bit variable-length integer from memory starting at p[0].
997 ** Return the number of bytes read.  The value is stored in *v.
998 **
999 ** If the varint stored in p[0] is larger than can fit in a 32-bit unsigned
1000 ** integer, then set *v to 0xffffffff.
1001 **
1002 ** A MACRO version, getVarint32, is provided which inlines the
1003 ** single-byte case.  All code should use the MACRO version as
1004 ** this function assumes the single-byte case has already been handled.
1005 */
1006 u8 sqlite3GetVarint32(const unsigned char *p, u32 *v){
1007   u32 a,b;
1008 
1009   /* The 1-byte case.  Overwhelmingly the most common.  Handled inline
1010   ** by the getVarin32() macro */
1011   a = *p;
1012   /* a: p0 (unmasked) */
1013 #ifndef getVarint32
1014   if (!(a&0x80))
1015   {
1016     /* Values between 0 and 127 */
1017     *v = a;
1018     return 1;
1019   }
1020 #endif
1021 
1022   /* The 2-byte case */
1023   p++;
1024   b = *p;
1025   /* b: p1 (unmasked) */
1026   if (!(b&0x80))
1027   {
1028     /* Values between 128 and 16383 */
1029     a &= 0x7f;
1030     a = a<<7;
1031     *v = a | b;
1032     return 2;
1033   }
1034 
1035   /* The 3-byte case */
1036   p++;
1037   a = a<<14;
1038   a |= *p;
1039   /* a: p0<<14 | p2 (unmasked) */
1040   if (!(a&0x80))
1041   {
1042     /* Values between 16384 and 2097151 */
1043     a &= (0x7f<<14)|(0x7f);
1044     b &= 0x7f;
1045     b = b<<7;
1046     *v = a | b;
1047     return 3;
1048   }
1049 
1050   /* A 32-bit varint is used to store size information in btrees.
1051   ** Objects are rarely larger than 2MiB limit of a 3-byte varint.
1052   ** A 3-byte varint is sufficient, for example, to record the size
1053   ** of a 1048569-byte BLOB or string.
1054   **
1055   ** We only unroll the first 1-, 2-, and 3- byte cases.  The very
1056   ** rare larger cases can be handled by the slower 64-bit varint
1057   ** routine.
1058   */
1059 #if 1
1060   {
1061     u64 v64;
1062     u8 n;
1063 
1064     p -= 2;
1065     n = sqlite3GetVarint(p, &v64);
1066     assert( n>3 && n<=9 );
1067     if( (v64 & SQLITE_MAX_U32)!=v64 ){
1068       *v = 0xffffffff;
1069     }else{
1070       *v = (u32)v64;
1071     }
1072     return n;
1073   }
1074 
1075 #else
1076   /* For following code (kept for historical record only) shows an
1077   ** unrolling for the 3- and 4-byte varint cases.  This code is
1078   ** slightly faster, but it is also larger and much harder to test.
1079   */
1080   p++;
1081   b = b<<14;
1082   b |= *p;
1083   /* b: p1<<14 | p3 (unmasked) */
1084   if (!(b&0x80))
1085   {
1086     /* Values between 2097152 and 268435455 */
1087     b &= (0x7f<<14)|(0x7f);
1088     a &= (0x7f<<14)|(0x7f);
1089     a = a<<7;
1090     *v = a | b;
1091     return 4;
1092   }
1093 
1094   p++;
1095   a = a<<14;
1096   a |= *p;
1097   /* a: p0<<28 | p2<<14 | p4 (unmasked) */
1098   if (!(a&0x80))
1099   {
1100     /* Values  between 268435456 and 34359738367 */
1101     a &= SLOT_4_2_0;
1102     b &= SLOT_4_2_0;
1103     b = b<<7;
1104     *v = a | b;
1105     return 5;
1106   }
1107 
1108   /* We can only reach this point when reading a corrupt database
1109   ** file.  In that case we are not in any hurry.  Use the (relatively
1110   ** slow) general-purpose sqlite3GetVarint() routine to extract the
1111   ** value. */
1112   {
1113     u64 v64;
1114     u8 n;
1115 
1116     p -= 4;
1117     n = sqlite3GetVarint(p, &v64);
1118     assert( n>5 && n<=9 );
1119     *v = (u32)v64;
1120     return n;
1121   }
1122 #endif
1123 }
1124 
1125 /*
1126 ** Return the number of bytes that will be needed to store the given
1127 ** 64-bit integer.
1128 */
1129 int sqlite3VarintLen(u64 v){
1130   int i;
1131   for(i=1; (v >>= 7)!=0; i++){ assert( i<10 ); }
1132   return i;
1133 }
1134 
1135 
1136 /*
1137 ** Read or write a four-byte big-endian integer value.
1138 */
1139 u32 sqlite3Get4byte(const u8 *p){
1140 #if SQLITE_BYTEORDER==4321
1141   u32 x;
1142   memcpy(&x,p,4);
1143   return x;
1144 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1145   u32 x;
1146   memcpy(&x,p,4);
1147   return __builtin_bswap32(x);
1148 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1149   u32 x;
1150   memcpy(&x,p,4);
1151   return _byteswap_ulong(x);
1152 #else
1153   testcase( p[0]&0x80 );
1154   return ((unsigned)p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
1155 #endif
1156 }
1157 void sqlite3Put4byte(unsigned char *p, u32 v){
1158 #if SQLITE_BYTEORDER==4321
1159   memcpy(p,&v,4);
1160 #elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4003000
1161   u32 x = __builtin_bswap32(v);
1162   memcpy(p,&x,4);
1163 #elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
1164   u32 x = _byteswap_ulong(v);
1165   memcpy(p,&x,4);
1166 #else
1167   p[0] = (u8)(v>>24);
1168   p[1] = (u8)(v>>16);
1169   p[2] = (u8)(v>>8);
1170   p[3] = (u8)v;
1171 #endif
1172 }
1173 
1174 
1175 
1176 /*
1177 ** Translate a single byte of Hex into an integer.
1178 ** This routine only works if h really is a valid hexadecimal
1179 ** character:  0..9a..fA..F
1180 */
1181 u8 sqlite3HexToInt(int h){
1182   assert( (h>='0' && h<='9') ||  (h>='a' && h<='f') ||  (h>='A' && h<='F') );
1183 #ifdef SQLITE_ASCII
1184   h += 9*(1&(h>>6));
1185 #endif
1186 #ifdef SQLITE_EBCDIC
1187   h += 9*(1&~(h>>4));
1188 #endif
1189   return (u8)(h & 0xf);
1190 }
1191 
1192 #if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
1193 /*
1194 ** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
1195 ** value.  Return a pointer to its binary value.  Space to hold the
1196 ** binary value has been obtained from malloc and must be freed by
1197 ** the calling routine.
1198 */
1199 void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
1200   char *zBlob;
1201   int i;
1202 
1203   zBlob = (char *)sqlite3DbMallocRawNN(db, n/2 + 1);
1204   n--;
1205   if( zBlob ){
1206     for(i=0; i<n; i+=2){
1207       zBlob[i/2] = (sqlite3HexToInt(z[i])<<4) | sqlite3HexToInt(z[i+1]);
1208     }
1209     zBlob[i/2] = 0;
1210   }
1211   return zBlob;
1212 }
1213 #endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
1214 
1215 /*
1216 ** Log an error that is an API call on a connection pointer that should
1217 ** not have been used.  The "type" of connection pointer is given as the
1218 ** argument.  The zType is a word like "NULL" or "closed" or "invalid".
1219 */
1220 static void logBadConnection(const char *zType){
1221   sqlite3_log(SQLITE_MISUSE,
1222      "API call with %s database connection pointer",
1223      zType
1224   );
1225 }
1226 
1227 /*
1228 ** Check to make sure we have a valid db pointer.  This test is not
1229 ** foolproof but it does provide some measure of protection against
1230 ** misuse of the interface such as passing in db pointers that are
1231 ** NULL or which have been previously closed.  If this routine returns
1232 ** 1 it means that the db pointer is valid and 0 if it should not be
1233 ** dereferenced for any reason.  The calling function should invoke
1234 ** SQLITE_MISUSE immediately.
1235 **
1236 ** sqlite3SafetyCheckOk() requires that the db pointer be valid for
1237 ** use.  sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
1238 ** open properly and is not fit for general use but which can be
1239 ** used as an argument to sqlite3_errmsg() or sqlite3_close().
1240 */
1241 int sqlite3SafetyCheckOk(sqlite3 *db){
1242   u32 magic;
1243   if( db==0 ){
1244     logBadConnection("NULL");
1245     return 0;
1246   }
1247   magic = db->magic;
1248   if( magic!=SQLITE_MAGIC_OPEN ){
1249     if( sqlite3SafetyCheckSickOrOk(db) ){
1250       testcase( sqlite3GlobalConfig.xLog!=0 );
1251       logBadConnection("unopened");
1252     }
1253     return 0;
1254   }else{
1255     return 1;
1256   }
1257 }
1258 int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
1259   u32 magic;
1260   magic = db->magic;
1261   if( magic!=SQLITE_MAGIC_SICK &&
1262       magic!=SQLITE_MAGIC_OPEN &&
1263       magic!=SQLITE_MAGIC_BUSY ){
1264     testcase( sqlite3GlobalConfig.xLog!=0 );
1265     logBadConnection("invalid");
1266     return 0;
1267   }else{
1268     return 1;
1269   }
1270 }
1271 
1272 /*
1273 ** Attempt to add, substract, or multiply the 64-bit signed value iB against
1274 ** the other 64-bit signed integer at *pA and store the result in *pA.
1275 ** Return 0 on success.  Or if the operation would have resulted in an
1276 ** overflow, leave *pA unchanged and return 1.
1277 */
1278 int sqlite3AddInt64(i64 *pA, i64 iB){
1279 #if GCC_VERSION>=5004000
1280   return __builtin_add_overflow(*pA, iB, pA);
1281 #else
1282   i64 iA = *pA;
1283   testcase( iA==0 ); testcase( iA==1 );
1284   testcase( iB==-1 ); testcase( iB==0 );
1285   if( iB>=0 ){
1286     testcase( iA>0 && LARGEST_INT64 - iA == iB );
1287     testcase( iA>0 && LARGEST_INT64 - iA == iB - 1 );
1288     if( iA>0 && LARGEST_INT64 - iA < iB ) return 1;
1289   }else{
1290     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 1 );
1291     testcase( iA<0 && -(iA + LARGEST_INT64) == iB + 2 );
1292     if( iA<0 && -(iA + LARGEST_INT64) > iB + 1 ) return 1;
1293   }
1294   *pA += iB;
1295   return 0;
1296 #endif
1297 }
1298 int sqlite3SubInt64(i64 *pA, i64 iB){
1299 #if GCC_VERSION>=5004000
1300   return __builtin_sub_overflow(*pA, iB, pA);
1301 #else
1302   testcase( iB==SMALLEST_INT64+1 );
1303   if( iB==SMALLEST_INT64 ){
1304     testcase( (*pA)==(-1) ); testcase( (*pA)==0 );
1305     if( (*pA)>=0 ) return 1;
1306     *pA -= iB;
1307     return 0;
1308   }else{
1309     return sqlite3AddInt64(pA, -iB);
1310   }
1311 #endif
1312 }
1313 int sqlite3MulInt64(i64 *pA, i64 iB){
1314 #if GCC_VERSION>=5004000
1315   return __builtin_mul_overflow(*pA, iB, pA);
1316 #else
1317   i64 iA = *pA;
1318   if( iB>0 ){
1319     if( iA>LARGEST_INT64/iB ) return 1;
1320     if( iA<SMALLEST_INT64/iB ) return 1;
1321   }else if( iB<0 ){
1322     if( iA>0 ){
1323       if( iB<SMALLEST_INT64/iA ) return 1;
1324     }else if( iA<0 ){
1325       if( iB==SMALLEST_INT64 ) return 1;
1326       if( iA==SMALLEST_INT64 ) return 1;
1327       if( -iA>LARGEST_INT64/-iB ) return 1;
1328     }
1329   }
1330   *pA = iA*iB;
1331   return 0;
1332 #endif
1333 }
1334 
1335 /*
1336 ** Compute the absolute value of a 32-bit signed integer, of possible.  Or
1337 ** if the integer has a value of -2147483648, return +2147483647
1338 */
1339 int sqlite3AbsInt32(int x){
1340   if( x>=0 ) return x;
1341   if( x==(int)0x80000000 ) return 0x7fffffff;
1342   return -x;
1343 }
1344 
1345 #ifdef SQLITE_ENABLE_8_3_NAMES
1346 /*
1347 ** If SQLITE_ENABLE_8_3_NAMES is set at compile-time and if the database
1348 ** filename in zBaseFilename is a URI with the "8_3_names=1" parameter and
1349 ** if filename in z[] has a suffix (a.k.a. "extension") that is longer than
1350 ** three characters, then shorten the suffix on z[] to be the last three
1351 ** characters of the original suffix.
1352 **
1353 ** If SQLITE_ENABLE_8_3_NAMES is set to 2 at compile-time, then always
1354 ** do the suffix shortening regardless of URI parameter.
1355 **
1356 ** Examples:
1357 **
1358 **     test.db-journal    =>   test.nal
1359 **     test.db-wal        =>   test.wal
1360 **     test.db-shm        =>   test.shm
1361 **     test.db-mj7f3319fa =>   test.9fa
1362 */
1363 void sqlite3FileSuffix3(const char *zBaseFilename, char *z){
1364 #if SQLITE_ENABLE_8_3_NAMES<2
1365   if( sqlite3_uri_boolean(zBaseFilename, "8_3_names", 0) )
1366 #endif
1367   {
1368     int i, sz;
1369     sz = sqlite3Strlen30(z);
1370     for(i=sz-1; i>0 && z[i]!='/' && z[i]!='.'; i--){}
1371     if( z[i]=='.' && ALWAYS(sz>i+4) ) memmove(&z[i+1], &z[sz-3], 4);
1372   }
1373 }
1374 #endif
1375 
1376 /*
1377 ** Find (an approximate) sum of two LogEst values.  This computation is
1378 ** not a simple "+" operator because LogEst is stored as a logarithmic
1379 ** value.
1380 **
1381 */
1382 LogEst sqlite3LogEstAdd(LogEst a, LogEst b){
1383   static const unsigned char x[] = {
1384      10, 10,                         /* 0,1 */
1385       9, 9,                          /* 2,3 */
1386       8, 8,                          /* 4,5 */
1387       7, 7, 7,                       /* 6,7,8 */
1388       6, 6, 6,                       /* 9,10,11 */
1389       5, 5, 5,                       /* 12-14 */
1390       4, 4, 4, 4,                    /* 15-18 */
1391       3, 3, 3, 3, 3, 3,              /* 19-24 */
1392       2, 2, 2, 2, 2, 2, 2,           /* 25-31 */
1393   };
1394   if( a>=b ){
1395     if( a>b+49 ) return a;
1396     if( a>b+31 ) return a+1;
1397     return a+x[a-b];
1398   }else{
1399     if( b>a+49 ) return b;
1400     if( b>a+31 ) return b+1;
1401     return b+x[b-a];
1402   }
1403 }
1404 
1405 /*
1406 ** Convert an integer into a LogEst.  In other words, compute an
1407 ** approximation for 10*log2(x).
1408 */
1409 LogEst sqlite3LogEst(u64 x){
1410   static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 };
1411   LogEst y = 40;
1412   if( x<8 ){
1413     if( x<2 ) return 0;
1414     while( x<8 ){  y -= 10; x <<= 1; }
1415   }else{
1416     while( x>255 ){ y += 40; x >>= 4; }  /*OPTIMIZATION-IF-TRUE*/
1417     while( x>15 ){  y += 10; x >>= 1; }
1418   }
1419   return a[x&7] + y - 10;
1420 }
1421 
1422 #ifndef SQLITE_OMIT_VIRTUALTABLE
1423 /*
1424 ** Convert a double into a LogEst
1425 ** In other words, compute an approximation for 10*log2(x).
1426 */
1427 LogEst sqlite3LogEstFromDouble(double x){
1428   u64 a;
1429   LogEst e;
1430   assert( sizeof(x)==8 && sizeof(a)==8 );
1431   if( x<=1 ) return 0;
1432   if( x<=2000000000 ) return sqlite3LogEst((u64)x);
1433   memcpy(&a, &x, 8);
1434   e = (a>>52) - 1022;
1435   return e*10;
1436 }
1437 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1438 
1439 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1440     defined(SQLITE_ENABLE_STAT3_OR_STAT4) || \
1441     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1442 /*
1443 ** Convert a LogEst into an integer.
1444 **
1445 ** Note that this routine is only used when one or more of various
1446 ** non-standard compile-time options is enabled.
1447 */
1448 u64 sqlite3LogEstToInt(LogEst x){
1449   u64 n;
1450   n = x%10;
1451   x /= 10;
1452   if( n>=5 ) n -= 2;
1453   else if( n>=1 ) n -= 1;
1454 #if defined(SQLITE_ENABLE_STMT_SCANSTATUS) || \
1455     defined(SQLITE_EXPLAIN_ESTIMATED_ROWS)
1456   if( x>60 ) return (u64)LARGEST_INT64;
1457 #else
1458   /* If only SQLITE_ENABLE_STAT3_OR_STAT4 is on, then the largest input
1459   ** possible to this routine is 310, resulting in a maximum x of 31 */
1460   assert( x<=60 );
1461 #endif
1462   return x>=3 ? (n+8)<<(x-3) : (n+8)>>(3-x);
1463 }
1464 #endif /* defined SCANSTAT or STAT4 or ESTIMATED_ROWS */
1465 
1466 /*
1467 ** Add a new name/number pair to a VList.  This might require that the
1468 ** VList object be reallocated, so return the new VList.  If an OOM
1469 ** error occurs, the original VList returned and the
1470 ** db->mallocFailed flag is set.
1471 **
1472 ** A VList is really just an array of integers.  To destroy a VList,
1473 ** simply pass it to sqlite3DbFree().
1474 **
1475 ** The first integer is the number of integers allocated for the whole
1476 ** VList.  The second integer is the number of integers actually used.
1477 ** Each name/number pair is encoded by subsequent groups of 3 or more
1478 ** integers.
1479 **
1480 ** Each name/number pair starts with two integers which are the numeric
1481 ** value for the pair and the size of the name/number pair, respectively.
1482 ** The text name overlays one or more following integers.  The text name
1483 ** is always zero-terminated.
1484 **
1485 ** Conceptually:
1486 **
1487 **    struct VList {
1488 **      int nAlloc;   // Number of allocated slots
1489 **      int nUsed;    // Number of used slots
1490 **      struct VListEntry {
1491 **        int iValue;    // Value for this entry
1492 **        int nSlot;     // Slots used by this entry
1493 **        // ... variable name goes here
1494 **      } a[0];
1495 **    }
1496 **
1497 ** During code generation, pointers to the variable names within the
1498 ** VList are taken.  When that happens, nAlloc is set to zero as an
1499 ** indication that the VList may never again be enlarged, since the
1500 ** accompanying realloc() would invalidate the pointers.
1501 */
1502 VList *sqlite3VListAdd(
1503   sqlite3 *db,           /* The database connection used for malloc() */
1504   VList *pIn,            /* The input VList.  Might be NULL */
1505   const char *zName,     /* Name of symbol to add */
1506   int nName,             /* Bytes of text in zName */
1507   int iVal               /* Value to associate with zName */
1508 ){
1509   int nInt;              /* number of sizeof(int) objects needed for zName */
1510   char *z;               /* Pointer to where zName will be stored */
1511   int i;                 /* Index in pIn[] where zName is stored */
1512 
1513   nInt = nName/4 + 3;
1514   assert( pIn==0 || pIn[0]>=3 );  /* Verify ok to add new elements */
1515   if( pIn==0 || pIn[1]+nInt > pIn[0] ){
1516     /* Enlarge the allocation */
1517     int nAlloc = (pIn ? pIn[0]*2 : 10) + nInt;
1518     VList *pOut = sqlite3DbRealloc(db, pIn, nAlloc*sizeof(int));
1519     if( pOut==0 ) return pIn;
1520     if( pIn==0 ) pOut[1] = 2;
1521     pIn = pOut;
1522     pIn[0] = nAlloc;
1523   }
1524   i = pIn[1];
1525   pIn[i] = iVal;
1526   pIn[i+1] = nInt;
1527   z = (char*)&pIn[i+2];
1528   pIn[1] = i+nInt;
1529   assert( pIn[1]<=pIn[0] );
1530   memcpy(z, zName, nName);
1531   z[nName] = 0;
1532   return pIn;
1533 }
1534 
1535 /*
1536 ** Return a pointer to the name of a variable in the given VList that
1537 ** has the value iVal.  Or return a NULL if there is no such variable in
1538 ** the list
1539 */
1540 const char *sqlite3VListNumToName(VList *pIn, int iVal){
1541   int i, mx;
1542   if( pIn==0 ) return 0;
1543   mx = pIn[1];
1544   i = 2;
1545   do{
1546     if( pIn[i]==iVal ) return (char*)&pIn[i+2];
1547     i += pIn[i+1];
1548   }while( i<mx );
1549   return 0;
1550 }
1551 
1552 /*
1553 ** Return the number of the variable named zName, if it is in VList.
1554 ** or return 0 if there is no such variable.
1555 */
1556 int sqlite3VListNameToNum(VList *pIn, const char *zName, int nName){
1557   int i, mx;
1558   if( pIn==0 ) return 0;
1559   mx = pIn[1];
1560   i = 2;
1561   do{
1562     const char *z = (const char*)&pIn[i+2];
1563     if( strncmp(z,zName,nName)==0 && z[nName]==0 ) return pIn[i];
1564     i += pIn[i+1];
1565   }while( i<mx );
1566   return 0;
1567 }
1568