/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.241 2008/07/28 19:34:54 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>
/*
** Return true if the floating point value is Not a Number (NaN).
*/
int sqlite3IsNaN(double x){
/* This NaN test sometimes fails if compiled on GCC with -ffast-math.
** On the other hand, the use of -ffast-math comes with the following
** warning:
**
** This option [-ffast-math] should never be turned on by any
** -O option since it can result in incorrect output for programs
** which depend on an exact implementation of IEEE or ISO
** rules/specifications for math functions.
**
** Under MSVC, this NaN test may fail if compiled with a floating-
** point precision mode other than /fp:precise. From the MSDN
** documentation:
**
** The compiler [with /fp:precise] will properly handle comparisons
** involving NaN. For example, x != x evaluates to true if x is NaN
** ...
*/
#ifdef __FAST_MATH__
# error SQLite will not work correctly with the -ffast-math option of GCC.
#endif
volatile double y = x;
volatile double z = y;
return y!=z;
}
/*
** Return the length of a string, except do not allow the string length
** to exceed the SQLITE_LIMIT_LENGTH setting.
*/
int sqlite3Strlen(sqlite3 *db, const char *z){
const char *z2 = z;
int len;
size_t x;
while( *z2 ){ z2++; }
x = z2 - z;
len = 0x7fffffff & x;
if( len!=x || len > db->aLimit[SQLITE_LIMIT_LENGTH] ){
return db->aLimit[SQLITE_LIMIT_LENGTH];
}else{
return len;
}
}
/*
** Set the most recent error code and error string for the sqlite
** handle "db". The error code is set to "err_code".
**
** If it is not NULL, string zFormat specifies the format of the
** error string in the style of the printf functions: The following
** format characters are allowed:
**
** %s Insert a string
** %z A string that should be freed after use
** %d Insert an integer
** %T Insert a token
** %S Insert the first element of a SrcList
**
** zFormat and any string tokens that follow it are assumed to be
** encoded in UTF-8.
**
** To clear the most recent error for sqlite handle "db", sqlite3Error
** should be called with err_code set to SQLITE_OK and zFormat set
** to NULL.
*/
void sqlite3Error(sqlite3 *db, int err_code, const char *zFormat, ...){
if( db && (db->pErr || (db->pErr = sqlite3ValueNew(db))!=0) ){
db->errCode = err_code;
if( zFormat ){
char *z;
va_list ap;
va_start(ap, zFormat);
z = sqlite3VMPrintf(db, zFormat, ap);
va_end(ap);
sqlite3ValueSetStr(db->pErr, -1, z, SQLITE_UTF8, SQLITE_DYNAMIC);
}else{
sqlite3ValueSetStr(db->pErr, 0, 0, SQLITE_UTF8, SQLITE_STATIC);
}
}
}
/*
** Add an error message to pParse->zErrMsg and increment pParse->nErr.
** The following formatting characters are allowed:
**
** %s Insert a string
** %z A string that should be freed after use
** %d Insert an integer
** %T Insert a token
** %S Insert the first element of a SrcList
**
** This function should be used to report any error that occurs whilst
** compiling an SQL statement (i.e. within sqlite3_prepare()). The
** last thing the sqlite3_prepare() function does is copy the error
** stored by this function into the database handle using sqlite3Error().
** Function sqlite3Error() should be used during statement execution
** (sqlite3_step() etc.).
*/
void sqlite3ErrorMsg(Parse *pParse, const char *zFormat, ...){
va_list ap;
sqlite3 *db = pParse->db;
pParse->nErr++;
sqlite3DbFree(db, pParse->zErrMsg);
va_start(ap, zFormat);
pParse->zErrMsg = sqlite3VMPrintf(db, zFormat, ap);
va_end(ap);
if( pParse->rc==SQLITE_OK ){
pParse->rc = SQLITE_ERROR;
}
}
/*
** Clear the error message in pParse, if any
*/
void sqlite3ErrorClear(Parse *pParse){
sqlite3DbFree(pParse->db, pParse->zErrMsg);
pParse->zErrMsg = 0;
pParse->nErr = 0;
}
/*
** Convert an SQL-style quoted string into a normal string by removing
** the quote characters. The conversion is done in-place. If the
** input does not begin with a quote character, then this routine
** is a no-op.
**
** 2002-Feb-14: This routine is extended to remove MS-Access style
** brackets from around identifers. For example: "[a-b-c]" becomes
** "a-b-c".
*/
void sqlite3Dequote(char *z){
int quote;
int i, j;
if( z==0 ) return;
quote = z[0];
switch( quote ){
case '\'': break;
case '"': break;
case '`': break; /* For MySQL compatibility */
case '[': quote = ']'; break; /* For MS SqlServer compatibility */
default: return;
}
for(i=1, j=0; z[i]; i++){
if( z[i]==quote ){
if( z[i+1]==quote ){
z[j++] = quote;
i++;
}else{
z[j++] = 0;
break;
}
}else{
z[j++] = z[i];
}
}
}
/* Convenient short-hand */
#define UpperToLower sqlite3UpperToLower
/*
** Some systems have stricmp(). Others have strcasecmp(). Because
** there is no consistency, we will define our own.
*/
int sqlite3StrICmp(const char *zLeft, const char *zRight){
register unsigned char *a, *b;
a = (unsigned char *)zLeft;
b = (unsigned char *)zRight;
while( *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
return UpperToLower[*a] - UpperToLower[*b];
}
int sqlite3StrNICmp(const char *zLeft, const char *zRight, int N){
register unsigned char *a, *b;
a = (unsigned char *)zLeft;
b = (unsigned char *)zRight;
while( N-- > 0 && *a!=0 && UpperToLower[*a]==UpperToLower[*b]){ a++; b++; }
return N<0 ? 0 : UpperToLower[*a] - UpperToLower[*b];
}
/*
** Return TRUE if z is a pure numeric string. Return FALSE if the
** string contains any character which is not part of a number. If
** the string is numeric and contains the '.' character, set *realnum
** to TRUE (otherwise FALSE).
**
** An empty string is considered non-numeric.
*/
int sqlite3IsNumber(const char *z, int *realnum, u8 enc){
int incr = (enc==SQLITE_UTF8?1:2);
if( enc==SQLITE_UTF16BE ) z++;
if( *z=='-' || *z=='+' ) z += incr;
if( !isdigit(*(u8*)z) ){
return 0;
}
z += incr;
if( realnum ) *realnum = 0;
while( isdigit(*(u8*)z) ){ z += incr; }
if( *z=='.' ){
z += incr;
if( !isdigit(*(u8*)z) ) return 0;
while( isdigit(*(u8*)z) ){ z += incr; }
if( realnum ) *realnum = 1;
}
if( *z=='e' || *z=='E' ){
z += incr;
if( *z=='+' || *z=='-' ) z += incr;
if( !isdigit(*(u8*)z) ) return 0;
while( isdigit(*(u8*)z) ){ z += incr; }
if( realnum ) *realnum = 1;
}
return *z==0;
}
/*
** The string z[] is an ascii representation of a real number.
** Convert this string to a double.
**
** This routine assumes that z[] really is a valid number. If it
** is not, the result is undefined.
**
** This routine is used instead of the library atof() function because
** the library atof() might want to use "," as the decimal point instead
** of "." depending on how locale is set. But that would cause problems
** for SQL. So this routine always uses "." regardless of locale.
*/
int sqlite3AtoF(const char *z, double *pResult){
#ifndef SQLITE_OMIT_FLOATING_POINT
int sign = 1;
const char *zBegin = z;
LONGDOUBLE_TYPE v1 = 0.0;
int nSignificant = 0;
while( isspace(*(u8*)z) ) z++;
if( *z=='-' ){
sign = -1;
z++;
}else if( *z=='+' ){
z++;
}
while( z[0]=='0' ){
z++;
}
while( isdigit(*(u8*)z) ){
v1 = v1*10.0 + (*z - '0');
z++;
nSignificant++;
}
if( *z=='.' ){
LONGDOUBLE_TYPE divisor = 1.0;
z++;
if( nSignificant==0 ){
while( z[0]=='0' ){
divisor *= 10.0;
z++;
}
}
while( isdigit(*(u8*)z) ){
if( nSignificant<18 ){
v1 = v1*10.0 + (*z - '0');
divisor *= 10.0;
nSignificant++;
}
z++;
}
v1 /= divisor;
}
if( *z=='e' || *z=='E' ){
int esign = 1;
int eval = 0;
LONGDOUBLE_TYPE scale = 1.0;
z++;
if( *z=='-' ){
esign = -1;
z++;
}else if( *z=='+' ){
z++;
}
while( isdigit(*(u8*)z) ){
eval = eval*10 + *z - '0';
z++;
}
while( eval>=64 ){ scale *= 1.0e+64; eval -= 64; }
while( eval>=16 ){ scale *= 1.0e+16; eval -= 16; }
while( eval>=4 ){ scale *= 1.0e+4; eval -= 4; }
while( eval>=1 ){ scale *= 1.0e+1; eval -= 1; }
if( esign<0 ){
v1 /= scale;
}else{
v1 *= scale;
}
}
*pResult = sign<0 ? -v1 : v1;
return z - zBegin;
#else
return sqlite3Atoi64(z, pResult);
#endif /* SQLITE_OMIT_FLOATING_POINT */
}
/*
** Compare the 19-character string zNum against the text representation
** value 2^63: 9223372036854775808. Return negative, zero, or positive
** if zNum is less than, equal to, or greater than the string.
**
** Unlike memcmp() this routine is guaranteed to return the difference
** in the values of the last digit if the only difference is in the
** last digit. So, for example,
**
** compare2pow63("9223372036854775800")
**
** will return -8.
*/
static int compare2pow63(const char *zNum){
int c;
c = memcmp(zNum,"922337203685477580",18);
if( c==0 ){
c = zNum[18] - '8';
}
return c;
}
/*
** Return TRUE if zNum is a 64-bit signed integer and write
** the value of the integer into *pNum. If zNum is not an integer
** or is an integer that is too large to be expressed with 64 bits,
** then return false.
**
** When this routine was originally written it dealt with only
** 32-bit numbers. At that time, it was much faster than the
** atoi() library routine in RedHat 7.2.
*/
int sqlite3Atoi64(const char *zNum, i64 *pNum){
i64 v = 0;
int neg;
int i, c;
const char *zStart;
while( isspace(*(u8*)zNum) ) zNum++;
if( *zNum=='-' ){
neg = 1;
zNum++;
}else if( *zNum=='+' ){
neg = 0;
zNum++;
}else{
neg = 0;
}
zStart = zNum;
while( zNum[0]=='0' ){ zNum++; } /* Skip over leading zeros. Ticket #2454 */
for(i=0; (c=zNum[i])>='0' && c<='9'; i++){
v = v*10 + c - '0';
}
*pNum = neg ? -v : v;
if( c!=0 || (i==0 && zStart==zNum) || i>19 ){
/* zNum is empty or contains non-numeric text or is longer
** than 19 digits (thus guaranting that it is too large) */
return 0;
}else if( i<19 ){
/* Less than 19 digits, so we know that it fits in 64 bits */
return 1;
}else{
/* 19-digit numbers must be no larger than 9223372036854775807 if positive
** or 9223372036854775808 if negative. Note that 9223372036854665808
** is 2^63. */
return compare2pow63(zNum)<neg;
}
}
/*
** The string zNum represents an integer. There might be some other
** information following the integer too, but that part is ignored.
** If the integer that the prefix of zNum represents will fit in a
** 64-bit signed integer, return TRUE. Otherwise return FALSE.
**
** This routine returns FALSE for the string -9223372036854775808 even that
** that number will, in theory fit in a 64-bit integer. Positive
** 9223373036854775808 will not fit in 64 bits. So it seems safer to return
** false.
*/
int sqlite3FitsIn64Bits(const char *zNum, int negFlag){
int i, c;
int neg = 0;
if( *zNum=='-' ){
neg = 1;
zNum++;
}else if( *zNum=='+' ){
zNum++;
}
if( negFlag ) neg = 1-neg;
while( *zNum=='0' ){
zNum++; /* Skip leading zeros. Ticket #2454 */
}
for(i=0; (c=zNum[i])>='0' && c<='9'; i++){}
if( i<19 ){
/* Guaranteed to fit if less than 19 digits */
return 1;
}else if( i>19 ){
/* Guaranteed to be too big if greater than 19 digits */
return 0;
}else{
/* Compare against 2^63. */
return compare2pow63(zNum)<neg;
}
}
/*
** If zNum represents an integer that will fit in 32-bits, then set
** *pValue to that integer and return true. Otherwise return false.
**
** Any non-numeric characters that following zNum are ignored.
** This is different from sqlite3Atoi64() which requires the
** input number to be zero-terminated.
*/
int sqlite3GetInt32(const char *zNum, int *pValue){
sqlite_int64 v = 0;
int i, c;
int neg = 0;
if( zNum[0]=='-' ){
neg = 1;
zNum++;
}else if( zNum[0]=='+' ){
zNum++;
}
while( zNum[0]=='0' ) zNum++;
for(i=0; i<11 && (c = zNum[i] - '0')>=0 && c<=9; i++){
v = v*10 + c;
}
/* The longest decimal representation of a 32 bit integer is 10 digits:
**
** 1234567890
** 2^31 -> 2147483648
*/
if( i>10 ){
return 0;
}
if( v-neg>2147483647 ){
return 0;
}
if( neg ){
v = -v;
}
*pValue = (int)v;
return 1;
}
/*
** The variable-length integer encoding is as follows:
**
** KEY:
** A = 0xxxxxxx 7 bits of data and one flag bit
** B = 1xxxxxxx 7 bits of data and one flag bit
** C = xxxxxxxx 8 bits of data
**
** 7 bits - A
** 14 bits - BA
** 21 bits - BBA
** 28 bits - BBBA
** 35 bits - BBBBA
** 42 bits - BBBBBA
** 49 bits - BBBBBBA
** 56 bits - BBBBBBBA
** 64 bits - BBBBBBBBC
*/
/*
** Write a 64-bit variable-length integer to memory starting at p[0].
** The length of data write will be between 1 and 9 bytes. The number
** of bytes written is returned.
**
** A variable-length integer consists of the lower 7 bits of each byte
** for all bytes that have the 8th bit set and one byte with the 8th
** bit clear. Except, if we get to the 9th byte, it stores the full
** 8 bits and is the last byte.
*/
int sqlite3PutVarint(unsigned char *p, u64 v){
int i, j, n;
u8 buf[10];
if( v & (((u64)0xff000000)<<32) ){
p[8] = v;
v >>= 8;
for(i=7; i>=0; i--){
p[i] = (v & 0x7f) | 0x80;
v >>= 7;
}
return 9;
}
n = 0;
do{
buf[n++] = (v & 0x7f) | 0x80;
v >>= 7;
}while( v!=0 );
buf[0] &= 0x7f;
assert( n<=9 );
for(i=0, j=n-1; j>=0; j--, i++){
p[i] = buf[j];
}
return n;
}
/*
** This routine is a faster version of sqlite3PutVarint() that only
** works for 32-bit positive integers and which is optimized for
** the common case of small integers. A MACRO version, putVarint32,
** is provided which inlines the single-byte case. All code should use
** the MACRO version as this function assumes the single-byte case has
** already been handled.
*/
int sqlite3PutVarint32(unsigned char *p, u32 v){
#ifndef putVarint32
if( (v & ~0x7f)==0 ){
p[0] = v;
return 1;
}
#endif
if( (v & ~0x3fff)==0 ){
p[0] = (v>>7) | 0x80;
p[1] = v & 0x7f;
return 2;
}
return sqlite3PutVarint(p, v);
}
/*
** Read a 64-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read. The value is stored in *v.
*/
int sqlite3GetVarint(const unsigned char *p, u64 *v){
u32 a,b,s;
a = *p;
/* a: p0 (unmasked) */
if (!(a&0x80))
{
*v = a;
return 1;
}
p++;
b = *p;
/* b: p1 (unmasked) */
if (!(b&0x80))
{
a &= 0x7f;
a = a<<7;
a |= b;
*v = a;
return 2;
}
p++;
a = a<<14;
a |= *p;
/* a: p0<<14 | p2 (unmasked) */
if (!(a&0x80))
{
a &= (0x7f<<14)|(0x7f);
b &= 0x7f;
b = b<<7;
a |= b;
*v = a;
return 3;
}
/* CSE1 from below */
a &= (0x7f<<14)|(0x7f);
p++;
b = b<<14;
b |= *p;
/* b: p1<<14 | p3 (unmasked) */
if (!(b&0x80))
{
b &= (0x7f<<14)|(0x7f);
/* moved CSE1 up */
/* a &= (0x7f<<14)|(0x7f); */
a = a<<7;
a |= b;
*v = a;
return 4;
}
/* a: p0<<14 | p2 (masked) */
/* b: p1<<14 | p3 (unmasked) */
/* 1:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
/* moved CSE1 up */
/* a &= (0x7f<<14)|(0x7f); */
b &= (0x7f<<14)|(0x7f);
s = a;
/* s: p0<<14 | p2 (masked) */
p++;
a = a<<14;
a |= *p;
/* a: p0<<28 | p2<<14 | p4 (unmasked) */
if (!(a&0x80))
{
/* we can skip these cause they were (effectively) done above in calc'ing s */
/* a &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
/* b &= (0x7f<<14)|(0x7f); */
b = b<<7;
a |= b;
s = s>>18;
*v = ((u64)s)<<32 | a;
return 5;
}
/* 2:save off p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
s = s<<7;
s |= b;
/* s: p0<<21 | p1<<14 | p2<<7 | p3 (masked) */
p++;
b = b<<14;
b |= *p;
/* b: p1<<28 | p3<<14 | p5 (unmasked) */
if (!(b&0x80))
{
/* we can skip this cause it was (effectively) done above in calc'ing s */
/* b &= (0x7f<<28)|(0x7f<<14)|(0x7f); */
a &= (0x7f<<14)|(0x7f);
a = a<<7;
a |= b;
s = s>>18;
*v = ((u64)s)<<32 | a;
return 6;
}
p++;
a = a<<14;
a |= *p;
/* a: p2<<28 | p4<<14 | p6 (unmasked) */
if (!(a&0x80))
{
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b &= (0x7f<<14)|(0x7f);
b = b<<7;
a |= b;
s = s>>11;
*v = ((u64)s)<<32 | a;
return 7;
}
/* CSE2 from below */
a &= (0x7f<<14)|(0x7f);
p++;
b = b<<14;
b |= *p;
/* b: p3<<28 | p5<<14 | p7 (unmasked) */
if (!(b&0x80))
{
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
/* moved CSE2 up */
/* a &= (0x7f<<14)|(0x7f); */
a = a<<7;
a |= b;
s = s>>4;
*v = ((u64)s)<<32 | a;
return 8;
}
p++;
a = a<<15;
a |= *p;
/* a: p4<<29 | p6<<15 | p8 (unmasked) */
/* moved CSE2 up */
/* a &= (0x7f<<29)|(0x7f<<15)|(0xff); */
b &= (0x7f<<14)|(0x7f);
b = b<<8;
a |= b;
s = s<<4;
b = p[-4];
b &= 0x7f;
b = b>>3;
s |= b;
*v = ((u64)s)<<32 | a;
return 9;
}
/*
** Read a 32-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read. The value is stored in *v.
** A MACRO version, getVarint32, is provided which inlines the
** single-byte case. All code should use the MACRO version as
** this function assumes the single-byte case has already been handled.
*/
int sqlite3GetVarint32(const unsigned char *p, u32 *v){
u32 a,b;
a = *p;
/* a: p0 (unmasked) */
#ifndef getVarint32
if (!(a&0x80))
{
*v = a;
return 1;
}
#endif
p++;
b = *p;
/* b: p1 (unmasked) */
if (!(b&0x80))
{
a &= 0x7f;
a = a<<7;
*v = a | b;
return 2;
}
p++;
a = a<<14;
a |= *p;
/* a: p0<<14 | p2 (unmasked) */
if (!(a&0x80))
{
a &= (0x7f<<14)|(0x7f);
b &= 0x7f;
b = b<<7;
*v = a | b;
return 3;
}
p++;
b = b<<14;
b |= *p;
/* b: p1<<14 | p3 (unmasked) */
if (!(b&0x80))
{
b &= (0x7f<<14)|(0x7f);
a &= (0x7f<<14)|(0x7f);
a = a<<7;
*v = a | b;
return 4;
}
p++;
a = a<<14;
a |= *p;
/* a: p0<<28 | p2<<14 | p4 (unmasked) */
if (!(a&0x80))
{
a &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b &= (0x7f<<28)|(0x7f<<14)|(0x7f);
b = b<<7;
*v = a | b;
return 5;
}
/* We can only reach this point when reading a corrupt database
** file. In that case we are not in any hurry. Use the (relatively
** slow) general-purpose sqlite3GetVarint() routine to extract the
** value. */
{
u64 v64;
int n;
p -= 4;
n = sqlite3GetVarint(p, &v64);
assert( n>5 && n<=9 );
*v = (u32)v64;
return n;
}
}
/*
** Return the number of bytes that will be needed to store the given
** 64-bit integer.
*/
int sqlite3VarintLen(u64 v){
int i = 0;
do{
i++;
v >>= 7;
}while( v!=0 && i<9 );
return i;
}
/*
** Read or write a four-byte big-endian integer value.
*/
u32 sqlite3Get4byte(const u8 *p){
return (p[0]<<24) | (p[1]<<16) | (p[2]<<8) | p[3];
}
void sqlite3Put4byte(unsigned char *p, u32 v){
p[0] = v>>24;
p[1] = v>>16;
p[2] = v>>8;
p[3] = v;
}
#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
/*
** Translate a single byte of Hex into an integer.
** This routinen only works if h really is a valid hexadecimal
** character: 0..9a..fA..F
*/
static int hexToInt(int h){
assert( (h>='0' && h<='9') || (h>='a' && h<='f') || (h>='A' && h<='F') );
#ifdef SQLITE_ASCII
h += 9*(1&(h>>6));
#endif
#ifdef SQLITE_EBCDIC
h += 9*(1&~(h>>4));
#endif
return h & 0xf;
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
#if !defined(SQLITE_OMIT_BLOB_LITERAL) || defined(SQLITE_HAS_CODEC)
/*
** Convert a BLOB literal of the form "x'hhhhhh'" into its binary
** value. Return a pointer to its binary value. Space to hold the
** binary value has been obtained from malloc and must be freed by
** the calling routine.
*/
void *sqlite3HexToBlob(sqlite3 *db, const char *z, int n){
char *zBlob;
int i;
zBlob = (char *)sqlite3DbMallocRaw(db, n/2 + 1);
n--;
if( zBlob ){
for(i=0; i<n; i+=2){
zBlob[i/2] = (hexToInt(z[i])<<4) | hexToInt(z[i+1]);
}
zBlob[i/2] = 0;
}
return zBlob;
}
#endif /* !SQLITE_OMIT_BLOB_LITERAL || SQLITE_HAS_CODEC */
/*
** Change the sqlite.magic from SQLITE_MAGIC_OPEN to SQLITE_MAGIC_BUSY.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_OPEN
** when this routine is called.
**
** This routine is called when entering an SQLite API. The SQLITE_MAGIC_OPEN
** value indicates that the database connection passed into the API is
** open and is not being used by another thread. By changing the value
** to SQLITE_MAGIC_BUSY we indicate that the connection is in use.
** sqlite3SafetyOff() below will change the value back to SQLITE_MAGIC_OPEN
** when the API exits.
**
** This routine is a attempt to detect if two threads use the
** same sqlite* pointer at the same time. There is a race
** condition so it is possible that the error is not detected.
** But usually the problem will be seen. The result will be an
** error which can be used to debug the application that is
** using SQLite incorrectly.
**
** Ticket #202: If db->magic is not a valid open value, take care not
** to modify the db structure at all. It could be that db is a stale
** pointer. In other words, it could be that there has been a prior
** call to sqlite3_close(db) and db has been deallocated. And we do
** not want to write into deallocated memory.
*/
#ifdef SQLITE_DEBUG
int sqlite3SafetyOn(sqlite3 *db){
if( db->magic==SQLITE_MAGIC_OPEN ){
db->magic = SQLITE_MAGIC_BUSY;
assert( sqlite3_mutex_held(db->mutex) );
return 0;
}else if( db->magic==SQLITE_MAGIC_BUSY ){
db->magic = SQLITE_MAGIC_ERROR;
db->u1.isInterrupted = 1;
}
return 1;
}
#endif
/*
** Change the magic from SQLITE_MAGIC_BUSY to SQLITE_MAGIC_OPEN.
** Return an error (non-zero) if the magic was not SQLITE_MAGIC_BUSY
** when this routine is called.
*/
#ifdef SQLITE_DEBUG
int sqlite3SafetyOff(sqlite3 *db){
if( db->magic==SQLITE_MAGIC_BUSY ){
db->magic = SQLITE_MAGIC_OPEN;
assert( sqlite3_mutex_held(db->mutex) );
return 0;
}else{
db->magic = SQLITE_MAGIC_ERROR;
db->u1.isInterrupted = 1;
return 1;
}
}
#endif
/*
** Check to make sure we have a valid db pointer. This test is not
** foolproof but it does provide some measure of protection against
** misuse of the interface such as passing in db pointers that are
** NULL or which have been previously closed. If this routine returns
** 1 it means that the db pointer is valid and 0 if it should not be
** dereferenced for any reason. The calling function should invoke
** SQLITE_MISUSE immediately.
**
** sqlite3SafetyCheckOk() requires that the db pointer be valid for
** use. sqlite3SafetyCheckSickOrOk() allows a db pointer that failed to
** open properly and is not fit for general use but which can be
** used as an argument to sqlite3_errmsg() or sqlite3_close().
*/
int sqlite3SafetyCheckOk(sqlite3 *db){
int magic;
if( db==0 ) return 0;
magic = db->magic;
if( magic!=SQLITE_MAGIC_OPEN &&
magic!=SQLITE_MAGIC_BUSY ) return 0;
return 1;
}
int sqlite3SafetyCheckSickOrOk(sqlite3 *db){
int magic;
if( db==0 ) return 0;
magic = db->magic;
if( magic!=SQLITE_MAGIC_SICK &&
magic!=SQLITE_MAGIC_OPEN &&
magic!=SQLITE_MAGIC_BUSY ) return 0;
return 1;
}