/*
** 2002 February 23
**
** 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.
**
*************************************************************************
** This file contains the C functions that implement various SQL
** functions of SQLite.
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.1 2004/10/15 01:07:11 mchirico Exp $
*/
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "sqliteInt.h"
#include "vdbeInt.h"
#include "os.h"
static CollSeq *sqlite3GetFuncCollSeq(sqlite3_context *context){
return context->pColl;
}
/*
** Implementation of the non-aggregate min() and max() functions
*/
static void minmaxFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
int i;
int mask; /* 0 for min() or 0xffffffff for max() */
int iBest;
CollSeq *pColl;
if( argc==0 ) return;
mask = sqlite3_user_data(context)==0 ? 0 : -1;
pColl = sqlite3GetFuncCollSeq(context);
assert( pColl );
assert( mask==-1 || mask==0 );
iBest = 0;
if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
for(i=1; i<argc; i++){
if( sqlite3_value_type(argv[i])==SQLITE_NULL ) return;
if( (sqlite3MemCompare(argv[iBest], argv[i], pColl)^mask)>=0 ){
iBest = i;
}
}
sqlite3_result_value(context, argv[iBest]);
}
/*
** Return the type of the argument.
*/
static void typeofFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
const char *z = 0;
switch( sqlite3_value_type(argv[0]) ){
case SQLITE_NULL: z = "null"; break;
case SQLITE_INTEGER: z = "integer"; break;
case SQLITE_TEXT: z = "text"; break;
case SQLITE_FLOAT: z = "real"; break;
case SQLITE_BLOB: z = "blob"; break;
}
sqlite3_result_text(context, z, -1, SQLITE_STATIC);
}
/*
** Implementation of the length() function
*/
static void lengthFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
int len;
assert( argc==1 );
switch( sqlite3_value_type(argv[0]) ){
case SQLITE_BLOB:
case SQLITE_INTEGER:
case SQLITE_FLOAT: {
sqlite3_result_int(context, sqlite3_value_bytes(argv[0]));
break;
}
case SQLITE_TEXT: {
const char *z = sqlite3_value_text(argv[0]);
for(len=0; *z; z++){ if( (0xc0&*z)!=0x80 ) len++; }
sqlite3_result_int(context, len);
break;
}
default: {
sqlite3_result_null(context);
break;
}
}
}
/*
** Implementation of the sign() function
*/
static void signFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
assert( argc==1 );
switch( sqlite3_value_type(argv[0]) ){
case SQLITE_INTEGER: {
i64 iVal = sqlite3_value_int64(argv[0]);
/* 1st change below. Line below was: if( iVal<0 ) iVal = iVal * -1; */
iVal = ( iVal > 0) ? 1 : ( iVal < 0 ) ? -1 : 0;
sqlite3_result_int64(context, iVal);
break;
}
case SQLITE_NULL: {
sqlite3_result_null(context);
break;
}
default: {
/* 2nd change below. Line for abs was: if( rVal<0 ) rVal = rVal * -1.0; */
double rVal = sqlite3_value_double(argv[0]);
rVal = ( rVal > 0) ? 1 : ( rVal < 0 ) ? -1 : 0;
sqlite3_result_double(context, rVal);
break;
}
}
}
/*
** Implementation of the abs() function
*/
static void absFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
assert( argc==1 );
switch( sqlite3_value_type(argv[0]) ){
case SQLITE_INTEGER: {
i64 iVal = sqlite3_value_int64(argv[0]);
if( iVal<0 ) iVal = iVal * -1;
sqlite3_result_int64(context, iVal);
break;
}
case SQLITE_NULL: {
sqlite3_result_null(context);
break;
}
default: {
double rVal = sqlite3_value_double(argv[0]);
if( rVal<0 ) rVal = rVal * -1.0;
sqlite3_result_double(context, rVal);
break;
}
}
}
/*
** Implementation of the substr() function
*/
static void substrFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
const char *z;
const char *z2;
int i;
int p1, p2, len;
assert( argc==3 );
z = sqlite3_value_text(argv[0]);
if( z==0 ) return;
p1 = sqlite3_value_int(argv[1]);
p2 = sqlite3_value_int(argv[2]);
for(len=0, z2=z; *z2; z2++){ if( (0xc0&*z2)!=0x80 ) len++; }
if( p1<0 ){
p1 += len;
if( p1<0 ){
p2 += p1;
p1 = 0;
}
}else if( p1>0 ){
p1--;
}
if( p1+p2>len ){
p2 = len-p1;
}
for(i=0; i<p1 && z[i]; i++){
if( (z[i]&0xc0)==0x80 ) p1++;
}
while( z[i] && (z[i]&0xc0)==0x80 ){ i++; p1++; }
for(; i<p1+p2 && z[i]; i++){
if( (z[i]&0xc0)==0x80 ) p2++;
}
while( z[i] && (z[i]&0xc0)==0x80 ){ i++; p2++; }
if( p2<0 ) p2 = 0;
sqlite3_result_text(context, &z[p1], p2, SQLITE_TRANSIENT);
}
/*
** Implementation of the round() function
*/
static void roundFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
int n = 0;
double r;
char zBuf[100];
assert( argc==1 || argc==2 );
if( argc==2 ){
if( SQLITE_NULL==sqlite3_value_type(argv[1]) ) return;
n = sqlite3_value_int(argv[1]);
if( n>30 ) n = 30;
if( n<0 ) n = 0;
}
if( SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;
r = sqlite3_value_double(argv[0]);
sprintf(zBuf,"%.*f",n,r);
sqlite3_result_text(context, zBuf, -1, SQLITE_TRANSIENT);
}
/*
** Implementation of the upper() and lower() SQL functions.
*/
static void upperFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
unsigned char *z;
int i;
if( argc<1 || SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;
z = sqliteMalloc(sqlite3_value_bytes(argv[0])+1);
if( z==0 ) return;
strcpy(z, sqlite3_value_text(argv[0]));
for(i=0; z[i]; i++){
z[i] = toupper(z[i]);
}
sqlite3_result_text(context, z, -1, SQLITE_TRANSIENT);
sqliteFree(z);
}
static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
unsigned char *z;
int i;
if( argc<1 || SQLITE_NULL==sqlite3_value_type(argv[0]) ) return;
z = sqliteMalloc(sqlite3_value_bytes(argv[0])+1);
if( z==0 ) return;
strcpy(z, sqlite3_value_text(argv[0]));
for(i=0; z[i]; i++){
z[i] = tolower(z[i]);
}
sqlite3_result_text(context, z, -1, SQLITE_TRANSIENT);
sqliteFree(z);
}
/*
** Implementation of the IFNULL(), NVL(), and COALESCE() functions.
** All three do the same thing. They return the first non-NULL
** argument.
*/
static void ifnullFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
int i;
for(i=0; i<argc; i++){
if( SQLITE_NULL!=sqlite3_value_type(argv[i]) ){
sqlite3_result_value(context, argv[i]);
break;
}
}
}
/*
** Implementation of random(). Return a random integer.
*/
static void randomFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
int r;
sqlite3Randomness(sizeof(r), &r);
sqlite3_result_int(context, r);
}
/*
** Implementation of the last_insert_rowid() SQL function. The return
** value is the same as the sqlite3_last_insert_rowid() API function.
*/
static void last_insert_rowid(
sqlite3_context *context,
int arg,
sqlite3_value **argv
){
sqlite3 *db = sqlite3_user_data(context);
sqlite3_result_int64(context, sqlite3_last_insert_rowid(db));
}
/*
** Implementation of the changes() SQL function. The return value is the
** same as the sqlite3_changes() API function.
*/
static void changes(
sqlite3_context *context,
int arg,
sqlite3_value **argv
){
sqlite3 *db = sqlite3_user_data(context);
sqlite3_result_int(context, sqlite3_changes(db));
}
/*
** Implementation of the total_changes() SQL function. The return value is
** the same as the sqlite3_total_changes() API function.
*/
static void total_changes(
sqlite3_context *context,
int arg,
sqlite3_value **argv
){
sqlite3 *db = sqlite3_user_data(context);
sqlite3_result_int(context, sqlite3_total_changes(db));
}
/*
** A structure defining how to do GLOB-style comparisons.
*/
struct compareInfo {
u8 matchAll;
u8 matchOne;
u8 matchSet;
u8 noCase;
};
static const struct compareInfo globInfo = { '*', '?', '[', 0 };
static const struct compareInfo likeInfo = { '%', '_', 0, 1 };
/*
** X is a pointer to the first byte of a UTF-8 character. Increment
** X so that it points to the next character. This only works right
** if X points to a well-formed UTF-8 string.
*/
#define sqliteNextChar(X) while( (0xc0&*++(X))==0x80 ){}
#define sqliteCharVal(X) sqlite3ReadUtf8(X)
/*
** Compare two UTF-8 strings for equality where the first string can
** potentially be a "glob" expression. Return true (1) if they
** are the same and false (0) if they are different.
**
** Globbing rules:
**
** '*' Matches any sequence of zero or more characters.
**
** '?' Matches exactly one character.
**
** [...] Matches one character from the enclosed list of
** characters.
**
** [^...] Matches one character not in the enclosed list.
**
** With the [...] and [^...] matching, a ']' character can be included
** in the list by making it the first character after '[' or '^'. A
** range of characters can be specified using '-'. Example:
** "[a-z]" matches any single lower-case letter. To match a '-', make
** it the last character in the list.
**
** This routine is usually quick, but can be N**2 in the worst case.
**
** Hints: to match '*' or '?', put them in "[]". Like this:
**
** abc[*]xyz Matches "abc*xyz" only
*/
int patternCompare(
const u8 *zPattern, /* The glob pattern */
const u8 *zString, /* The string to compare against the glob */
const struct compareInfo *pInfo /* Information about how to do the compare */
){
register int c;
int invert;
int seen;
int c2;
u8 matchOne = pInfo->matchOne;
u8 matchAll = pInfo->matchAll;
u8 matchSet = pInfo->matchSet;
u8 noCase = pInfo->noCase;
while( (c = *zPattern)!=0 ){
if( c==matchAll ){
while( (c=zPattern[1]) == matchAll || c == matchOne ){
if( c==matchOne ){
if( *zString==0 ) return 0;
sqliteNextChar(zString);
}
zPattern++;
}
if( c==0 ) return 1;
if( c==matchSet ){
while( *zString && patternCompare(&zPattern[1],zString,pInfo)==0 ){
sqliteNextChar(zString);
}
return *zString!=0;
}else{
while( (c2 = *zString)!=0 ){
if( noCase ){
c2 = sqlite3UpperToLower[c2];
c = sqlite3UpperToLower[c];
while( c2 != 0 && c2 != c ){ c2 = sqlite3UpperToLower[*++zString]; }
}else{
while( c2 != 0 && c2 != c ){ c2 = *++zString; }
}
if( c2==0 ) return 0;
if( patternCompare(&zPattern[1],zString,pInfo) ) return 1;
sqliteNextChar(zString);
}
return 0;
}
}else if( c==matchOne ){
if( *zString==0 ) return 0;
sqliteNextChar(zString);
zPattern++;
}else if( c==matchSet ){
int prior_c = 0;
seen = 0;
invert = 0;
c = sqliteCharVal(zString);
if( c==0 ) return 0;
c2 = *++zPattern;
if( c2=='^' ){ invert = 1; c2 = *++zPattern; }
if( c2==']' ){
if( c==']' ) seen = 1;
c2 = *++zPattern;
}
while( (c2 = sqliteCharVal(zPattern))!=0 && c2!=']' ){
if( c2=='-' && zPattern[1]!=']' && zPattern[1]!=0 && prior_c>0 ){
zPattern++;
c2 = sqliteCharVal(zPattern);
if( c>=prior_c && c<=c2 ) seen = 1;
prior_c = 0;
}else if( c==c2 ){
seen = 1;
prior_c = c2;
}else{
prior_c = c2;
}
sqliteNextChar(zPattern);
}
if( c2==0 || (seen ^ invert)==0 ) return 0;
sqliteNextChar(zString);
zPattern++;
}else{
if( noCase ){
if( sqlite3UpperToLower[c] != sqlite3UpperToLower[*zString] ) return 0;
}else{
if( c != *zString ) return 0;
}
zPattern++;
zString++;
}
}
return *zString==0;
}
/*
** Implementation of the like() SQL function. This function implements
** the build-in LIKE operator. The first argument to the function is the
** pattern and the second argument is the string. So, the SQL statements:
**
** A LIKE B
**
** is implemented as like(B,A).
**
** If the pointer retrieved by via a call to sqlite3_user_data() is
** not NULL, then this function uses UTF-16. Otherwise UTF-8.
*/
static void likeFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
const unsigned char *zA = sqlite3_value_text(argv[0]);
const unsigned char *zB = sqlite3_value_text(argv[1]);
if( zA && zB ){
sqlite3_result_int(context, patternCompare(zA, zB, &likeInfo));
}
}
/*
** Implementation of the glob() SQL function. This function implements
** the build-in GLOB operator. The first argument to the function is the
** string and the second argument is the pattern. So, the SQL statements:
**
** A GLOB B
**
** is implemented as glob(A,B).
*/
static void globFunc(sqlite3_context *context, int arg, sqlite3_value **argv){
const unsigned char *zA = sqlite3_value_text(argv[0]);
const unsigned char *zB = sqlite3_value_text(argv[1]);
if( zA && zB ){
sqlite3_result_int(context, patternCompare(zA, zB, &globInfo));
}
}
/*
** Implementation of the NULLIF(x,y) function. The result is the first
** argument if the arguments are different. The result is NULL if the
** arguments are equal to each other.
*/
static void nullifFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
CollSeq *pColl = sqlite3GetFuncCollSeq(context);
if( sqlite3MemCompare(argv[0], argv[1], pColl)!=0 ){
sqlite3_result_value(context, argv[0]);
}
}
/*
** Implementation of the VERSION(*) function. The result is the version
** of the SQLite library that is running.
*/
static void versionFunc(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
sqlite3_result_text(context, sqlite3_version, -1, SQLITE_STATIC);
}
/*
** EXPERIMENTAL - This is not an official function. The interface may
** change. This function may disappear. Do not write code that depends
** on this function.
**
** Implementation of the QUOTE() function. This function takes a single
** argument. If the argument is numeric, the return value is the same as
** the argument. If the argument is NULL, the return value is the string
** "NULL". Otherwise, the argument is enclosed in single quotes with
** single-quote escapes.
*/
static void quoteFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
if( argc<1 ) return;
switch( sqlite3_value_type(argv[0]) ){
case SQLITE_NULL: {
sqlite3_result_text(context, "NULL", 4, SQLITE_STATIC);
break;
}
case SQLITE_INTEGER:
case SQLITE_FLOAT: {
sqlite3_result_value(context, argv[0]);
break;
}
case SQLITE_BLOB: {
static const char hexdigits[] = {
'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
char *zText = 0;
int nBlob = sqlite3_value_bytes(argv[0]);
char const *zBlob = sqlite3_value_blob(argv[0]);
zText = (char *)sqliteMalloc((2*nBlob)+4);
if( !zText ){
sqlite3_result_error(context, "out of memory", -1);
}else{
int i;
for(i=0; i<nBlob; i++){
zText[(i*2)+2] = hexdigits[(zBlob[i]>>4)&0x0F];
zText[(i*2)+3] = hexdigits[(zBlob[i])&0x0F];
}
zText[(nBlob*2)+2] = '\'';
zText[(nBlob*2)+3] = '\0';
zText[0] = 'X';
zText[1] = '\'';
sqlite3_result_text(context, zText, -1, SQLITE_TRANSIENT);
sqliteFree(zText);
}
break;
}
case SQLITE_TEXT: {
int i,j,n;
const char *zArg = sqlite3_value_text(argv[0]);
char *z;
for(i=n=0; zArg[i]; i++){ if( zArg[i]=='\'' ) n++; }
z = sqliteMalloc( i+n+3 );
if( z==0 ) return;
z[0] = '\'';
for(i=0, j=1; zArg[i]; i++){
z[j++] = zArg[i];
if( zArg[i]=='\'' ){
z[j++] = '\'';
}
}
z[j++] = '\'';
z[j] = 0;
sqlite3_result_text(context, z, j, SQLITE_TRANSIENT);
sqliteFree(z);
}
}
}
#ifdef SQLITE_SOUNDEX
/*
** Compute the soundex encoding of a word.
*/
static void soundexFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
char zResult[8];
const u8 *zIn;
int i, j;
static const unsigned char iCode[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 1, 2, 3, 0, 1, 2, 0, 0, 2, 2, 4, 5, 5, 0,
1, 2, 6, 2, 3, 0, 1, 0, 2, 0, 2, 0, 0, 0, 0, 0,
0, 0, 1, 2, 3, 0, 1, 2, 0, 0, 2, 2, 4, 5, 5, 0,
1, 2, 6, 2, 3, 0, 1, 0, 2, 0, 2, 0, 0, 0, 0, 0,
};
assert( argc==1 );
zIn = (u8*)sqlite3_value_text(argv[0]);
for(i=0; zIn[i] && !isalpha(zIn[i]); i++){}
if( zIn[i] ){
zResult[0] = toupper(zIn[i]);
for(j=1; j<4 && zIn[i]; i++){
int code = iCode[zIn[i]&0x7f];
if( code>0 ){
zResult[j++] = code + '0';
}
}
while( j<4 ){
zResult[j++] = '0';
}
zResult[j] = 0;
sqlite3_result_text(context, zResult, 4, SQLITE_TRANSIENT);
}else{
sqlite3_result_text(context, "?000", 4, SQLITE_STATIC);
}
}
#endif
#ifdef SQLITE_TEST
/*
** This function generates a string of random characters. Used for
** generating test data.
*/
static void randStr(sqlite3_context *context, int argc, sqlite3_value **argv){
static const unsigned char zSrc[] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"0123456789"
".-!,:*^+=_|?/<> ";
int iMin, iMax, n, r, i;
unsigned char zBuf[1000];
if( argc>=1 ){
iMin = sqlite3_value_int(argv[0]);
if( iMin<0 ) iMin = 0;
if( iMin>=sizeof(zBuf) ) iMin = sizeof(zBuf)-1;
}else{
iMin = 1;
}
if( argc>=2 ){
iMax = sqlite3_value_int(argv[1]);
if( iMax<iMin ) iMax = iMin;
if( iMax>=sizeof(zBuf) ) iMax = sizeof(zBuf)-1;
}else{
iMax = 50;
}
n = iMin;
if( iMax>iMin ){
sqlite3Randomness(sizeof(r), &r);
r &= 0x7fffffff;
n += r%(iMax + 1 - iMin);
}
assert( n<sizeof(zBuf) );
sqlite3Randomness(n, zBuf);
for(i=0; i<n; i++){
zBuf[i] = zSrc[zBuf[i]%(sizeof(zSrc)-1)];
}
zBuf[n] = 0;
sqlite3_result_text(context, zBuf, n, SQLITE_TRANSIENT);
}
#endif /* SQLITE_TEST */
#ifdef SQLITE_TEST
/*
** The following two SQL functions are used to test returning a text
** result with a destructor. Function 'test_destructor' takes one argument
** and returns the same argument interpreted as TEXT. A destructor is
** passed with the sqlite3_result_text() call.
**
** SQL function 'test_destructor_count' returns the number of outstanding
** allocations made by 'test_destructor';
**
** WARNING: Not threadsafe.
*/
static int test_destructor_count_var = 0;
static void destructor(void *p){
char *zVal = (char *)p;
assert(zVal);
zVal--;
sqliteFree(zVal);
test_destructor_count_var--;
}
static void test_destructor(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **argv
){
char *zVal;
int len;
sqlite3 *db = sqlite3_user_data(pCtx);
test_destructor_count_var++;
assert( nArg==1 );
if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
len = sqlite3ValueBytes(argv[0], db->enc);
zVal = sqliteMalloc(len+3);
zVal[len] = 0;
zVal[len-1] = 0;
assert( zVal );
zVal++;
memcpy(zVal, sqlite3ValueText(argv[0], db->enc), len);
if( db->enc==SQLITE_UTF8 ){
sqlite3_result_text(pCtx, zVal, -1, destructor);
}else if( db->enc==SQLITE_UTF16LE ){
sqlite3_result_text16le(pCtx, zVal, -1, destructor);
}else{
sqlite3_result_text16be(pCtx, zVal, -1, destructor);
}
}
static void test_destructor_count(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **argv
){
sqlite3_result_int(pCtx, test_destructor_count_var);
}
#endif /* SQLITE_TEST */
#ifdef SQLITE_TEST
/*
** Routines for testing the sqlite3_get_auxdata() and sqlite3_set_auxdata()
** interface.
**
** The test_auxdata() SQL function attempts to register each of its arguments
** as auxiliary data. If there are no prior registrations of aux data for
** that argument (meaning the argument is not a constant or this is its first
** call) then the result for that argument is 0. If there is a prior
** registration, the result for that argument is 1. The overall result
** is the individual argument results separated by spaces.
*/
static void free_test_auxdata(void *p) {sqliteFree(p);}
static void test_auxdata(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **argv
){
int i;
char *zRet = sqliteMalloc(nArg*2);
if( !zRet ) return;
for(i=0; i<nArg; i++){
char const *z = sqlite3_value_text(argv[i]);
if( z ){
char *zAux = sqlite3_get_auxdata(pCtx, i);
if( zAux ){
zRet[i*2] = '1';
if( strcmp(zAux, z) ){
sqlite3_result_error(pCtx, "Auxilary data corruption", -1);
return;
}
}else{
zRet[i*2] = '0';
zAux = sqliteStrDup(z);
sqlite3_set_auxdata(pCtx, i, zAux, free_test_auxdata);
}
zRet[i*2+1] = ' ';
}
}
sqlite3_result_text(pCtx, zRet, 2*nArg-1, free_test_auxdata);
}
#endif /* SQLITE_TEST */
/*
** An instance of the following structure holds the context of a
** sum() or avg() aggregate computation.
*/
typedef struct SumCtx SumCtx;
struct SumCtx {
double sum; /* Sum of terms */
int cnt; /* Number of elements summed */
};
/*
** Routines used to compute the sum or average.
*/
static void sumStep(sqlite3_context *context, int argc, sqlite3_value **argv){
SumCtx *p;
if( argc<1 ) return;
p = sqlite3_aggregate_context(context, sizeof(*p));
if( p && SQLITE_NULL!=sqlite3_value_type(argv[0]) ){
p->sum += sqlite3_value_double(argv[0]);
p->cnt++;
}
}
static void sumFinalize(sqlite3_context *context){
SumCtx *p;
p = sqlite3_aggregate_context(context, sizeof(*p));
sqlite3_result_double(context, p ? p->sum : 0.0);
}
static void avgFinalize(sqlite3_context *context){
SumCtx *p;
p = sqlite3_aggregate_context(context, sizeof(*p));
if( p && p->cnt>0 ){
sqlite3_result_double(context, p->sum/(double)p->cnt);
}
}
/*
** An instance of the following structure holds the context of a
** variance or standard deviation computation.
*/
typedef struct StdDevCtx StdDevCtx;
struct StdDevCtx {
double sum; /* Sum of terms */
double sum2; /* Sum of the squares of terms */
int cnt; /* Number of terms counted */
};
#if 0 /* Omit because math library is required */
/*
** Routines used to compute the standard deviation as an aggregate.
*/
static void stdDevStep(sqlite3_context *context, int argc, const char **argv){
StdDevCtx *p;
double x;
if( argc<1 ) return;
p = sqlite3_aggregate_context(context, sizeof(*p));
if( p && argv[0] ){
x = sqlite3AtoF(argv[0], 0);
p->sum += x;
p->sum2 += x*x;
p->cnt++;
}
}
static void stdDevFinalize(sqlite3_context *context){
double rN = sqlite3_aggregate_count(context);
StdDevCtx *p = sqlite3_aggregate_context(context, sizeof(*p));
if( p && p->cnt>1 ){
double rCnt = cnt;
sqlite3_set_result_double(context,
sqrt((p->sum2 - p->sum*p->sum/rCnt)/(rCnt-1.0)));
}
}
#endif
/*
** The following structure keeps track of state information for the
** count() aggregate function.
*/
typedef struct CountCtx CountCtx;
struct CountCtx {
int n;
};
/*
** Routines to implement the count() aggregate function.
*/
static void countStep(sqlite3_context *context, int argc, sqlite3_value **argv){
CountCtx *p;
p = sqlite3_aggregate_context(context, sizeof(*p));
if( (argc==0 || SQLITE_NULL!=sqlite3_value_type(argv[0])) && p ){
p->n++;
}
}
static void countFinalize(sqlite3_context *context){
CountCtx *p;
p = sqlite3_aggregate_context(context, sizeof(*p));
sqlite3_result_int(context, p ? p->n : 0);
}
/*
** This function tracks state information for the min() and max()
** aggregate functions.
*/
typedef struct MinMaxCtx MinMaxCtx;
struct MinMaxCtx {
char *z; /* The best so far */
char zBuf[28]; /* Space that can be used for storage */
};
/*
** Routines to implement min() and max() aggregate functions.
*/
static void minmaxStep(sqlite3_context *context, int argc, sqlite3_value **argv){
Mem *pArg = (Mem *)argv[0];
Mem *pBest;
if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
pBest = (Mem *)sqlite3_aggregate_context(context, sizeof(*pBest));
if( !pBest ) return;
if( pBest->flags ){
int max;
int cmp;
CollSeq *pColl = sqlite3GetFuncCollSeq(context);
/* This step function is used for both the min() and max() aggregates,
** the only difference between the two being that the sense of the
** comparison is inverted. For the max() aggregate, the
** sqlite3_user_data() function returns (void *)-1. For min() it
** returns (void *)db, where db is the sqlite3* database pointer.
** Therefore the next statement sets variable 'max' to 1 for the max()
** aggregate, or 0 for min().
*/
max = ((sqlite3_user_data(context)==(void *)-1)?1:0);
cmp = sqlite3MemCompare(pBest, pArg, pColl);
if( (max && cmp<0) || (!max && cmp>0) ){
sqlite3VdbeMemCopy(pBest, pArg);
}
}else{
sqlite3VdbeMemCopy(pBest, pArg);
}
}
static void minMaxFinalize(sqlite3_context *context){
sqlite3_value *pRes;
pRes = (sqlite3_value *)sqlite3_aggregate_context(context, sizeof(Mem));
if( pRes->flags ){
sqlite3_result_value(context, pRes);
}
sqlite3VdbeMemRelease(pRes);
}
/*
** This function registered all of the above C functions as SQL
** functions. This should be the only routine in this file with
** external linkage.
*/
void sqlite3RegisterBuiltinFunctions(sqlite3 *db){
static const struct {
char *zName;
signed char nArg;
u8 argType; /* 0: none. 1: db 2: (-1) */
u8 eTextRep; /* 1: UTF-16. 0: UTF-8 */
u8 needCollSeq;
void (*xFunc)(sqlite3_context*,int,sqlite3_value **);
} aFuncs[] = {
{ "min", -1, 0, SQLITE_UTF8, 1, minmaxFunc },
{ "min", 0, 0, SQLITE_UTF8, 1, 0 },
{ "max", -1, 2, SQLITE_UTF8, 1, minmaxFunc },
{ "max", 0, 2, SQLITE_UTF8, 1, 0 },
{ "typeof", 1, 0, SQLITE_UTF8, 0, typeofFunc },
{ "length", 1, 0, SQLITE_UTF8, 0, lengthFunc },
{ "substr", 3, 0, SQLITE_UTF8, 0, substrFunc },
{ "substr", 3, 0, SQLITE_UTF16LE, 0, sqlite3utf16Substr },
/* Added here */
{ "sign", 1, 0, SQLITE_UTF8, 0, signFunc },
{ "abs", 1, 0, SQLITE_UTF8, 0, absFunc },
{ "round", 1, 0, SQLITE_UTF8, 0, roundFunc },
{ "round", 2, 0, SQLITE_UTF8, 0, roundFunc },
{ "upper", 1, 0, SQLITE_UTF8, 0, upperFunc },
{ "lower", 1, 0, SQLITE_UTF8, 0, lowerFunc },
{ "coalesce", -1, 0, SQLITE_UTF8, 0, ifnullFunc },
{ "coalesce", 0, 0, SQLITE_UTF8, 0, 0 },
{ "coalesce", 1, 0, SQLITE_UTF8, 0, 0 },
{ "ifnull", 2, 0, SQLITE_UTF8, 1, ifnullFunc },
{ "random", -1, 0, SQLITE_UTF8, 0, randomFunc },
{ "like", 2, 0, SQLITE_UTF8, 0, likeFunc },
{ "glob", 2, 0, SQLITE_UTF8, 0, globFunc },
{ "nullif", 2, 0, SQLITE_UTF8, 1, nullifFunc },
{ "sqlite_version", 0, 0, SQLITE_UTF8, 0, versionFunc},
{ "quote", 1, 0, SQLITE_UTF8, 0, quoteFunc },
{ "last_insert_rowid", 0, 1, SQLITE_UTF8, 0, last_insert_rowid },
{ "changes", 0, 1, SQLITE_UTF8, 0, changes },
{ "total_changes", 0, 1, SQLITE_UTF8, 0, total_changes },
#ifdef SQLITE_SOUNDEX
{ "soundex", 1, 0, SQLITE_UTF8, 0, soundexFunc},
#endif
#ifdef SQLITE_TEST
{ "randstr", 2, 0, SQLITE_UTF8, 0, randStr },
{ "test_destructor", 1, 1, SQLITE_UTF8, 0, test_destructor},
{ "test_destructor_count", 0, 0, SQLITE_UTF8, 0, test_destructor_count},
{ "test_auxdata", -1, 0, SQLITE_UTF8, 0, test_auxdata},
#endif
};
static const struct {
char *zName;
signed char nArg;
u8 argType;
u8 needCollSeq;
void (*xStep)(sqlite3_context*,int,sqlite3_value**);
void (*xFinalize)(sqlite3_context*);
} aAggs[] = {
{ "min", 1, 0, 1, minmaxStep, minMaxFinalize },
{ "max", 1, 2, 1, minmaxStep, minMaxFinalize },
{ "sum", 1, 0, 0, sumStep, sumFinalize },
{ "avg", 1, 0, 0, sumStep, avgFinalize },
{ "count", 0, 0, 0, countStep, countFinalize },
{ "count", 1, 0, 0, countStep, countFinalize },
#if 0
{ "stddev", 1, 0, stdDevStep, stdDevFinalize },
#endif
};
int i;
for(i=0; i<sizeof(aFuncs)/sizeof(aFuncs[0]); i++){
void *pArg = 0;
switch( aFuncs[i].argType ){
case 1: pArg = db; break;
case 2: pArg = (void *)(-1); break;
}
sqlite3_create_function(db, aFuncs[i].zName, aFuncs[i].nArg,
aFuncs[i].eTextRep, pArg, aFuncs[i].xFunc, 0, 0);
if( aFuncs[i].needCollSeq ){
FuncDef *pFunc = sqlite3FindFunction(db, aFuncs[i].zName,
strlen(aFuncs[i].zName), aFuncs[i].nArg, aFuncs[i].eTextRep, 0);
if( pFunc && aFuncs[i].needCollSeq ){
pFunc->needCollSeq = 1;
}
}
}
for(i=0; i<sizeof(aAggs)/sizeof(aAggs[0]); i++){
void *pArg = 0;
switch( aAggs[i].argType ){
case 1: pArg = db; break;
case 2: pArg = (void *)(-1); break;
}
sqlite3_create_function(db, aAggs[i].zName, aAggs[i].nArg, SQLITE_UTF8,
pArg, 0, aAggs[i].xStep, aAggs[i].xFinalize);
if( aAggs[i].needCollSeq ){
FuncDef *pFunc = sqlite3FindFunction( db, aAggs[i].zName,
strlen(aAggs[i].zName), aAggs[i].nArg, SQLITE_UTF8, 0);
if( pFunc && aAggs[i].needCollSeq ){
pFunc->needCollSeq = 1;
}
}
}
sqlite3RegisterDateTimeFunctions(db);
}
Linux System Admin Tips: There are over 200 Linux tips and tricks in this article. That is over 100 pages covering everything from NTP, setting up 2 IP address on one NIC, sharing directories among several users, putting running jobs in the background, find out who is doing what on your system by examining open sockets and the ps command, how to watch a file, how to prevent even root from deleting a file, tape commands, setting up cron jobs, using rsync, using screen conveniently with emacs, how to kill every process for a user, security tips and a lot more. These tip grow weekly. The above link will download the text version for easy grep searching. There is also an html version here.
Breaking Firewalls with OpenSSH and PuTTY: If the system administrator deliberately filters out all traffic except port 22 (ssh), to a single server, it is very likely that you can still gain access other computers behind the firewall. This article shows how remote Linux and Windows users can gain access to firewalled samba, mail, and http servers. In essence, it shows how openSSH and Putty can be used as a VPN solution for your home or workplace.
MySQL Tips and Tricks: Find out who is doing what in MySQL and how to kill the process, create binary log files, connect, create and select with Perl and Java, remove duplicates in a table with the index command, rollback and how to apply, merging several tables into one, updating foreign keys, monitor port 3306 with the tcpdump command, creating a C API, complex selects, and much more.
Create a Live Linux CD - BusyBox and OpenSSH Included: These steps will show you how to create a functioning Linux system, with the latest 2.6 kernel compiled from source, and how to integrate the BusyBox utilities including the installation of DHCP. Plus, how to compile in the OpenSSH package on this CD based system. On system boot-up a filesystem will be created and the contents from the CD will be uncompressed and completely loaded into RAM -- the CD could be removed at this point for boot-up on a second computer. The remaining functioning system will have full ssh capabilities. You can take over any PC assuming, of course, you have configured the kernel with the appropriate drivers and the PC can boot from a CD. This tutorial steps you through the whole processes.
SQLite Tutorial : This article explores the power and simplicity of sqlite3, first by starting with common commands and triggers, then the attach statement with the union operation is introduced in a way that allows multiple tables, in separate databases, to be combined as one virtual table, without the overhead of copying or moving data. Next, the simple sign function and the amazingly powerful trick of using this function in SQL select statements to solve complex queries with a single pass through the data is demonstrated, after making a brief mathematical case for how the sign function defines the absolute value and IF conditions.
The Lemon Parser Tutorial: This article explains how to build grammars and programs using the lemon parser, which is faster than yacc. And, unlike yacc, it is thread safe.
How to Compile the 2.6 kernel for Red Hat 9 and 8.0 and get Fedora Updates: This is a step by step tutorial on how to compile the 2.6 kernel from source.
Virtual Filesystem: Building A Linux Filesystem From An Ordinary File. You can take a disk file, format it as ext2, ext3, or reiser filesystem and then mount it, just like a physical drive. Yes, it then possible to read and write files to this newly mounted device. You can also copy the complete filesystem, since it is just a file, to another computer. If security is an issue, read on. This article will show you how to encrypt the filesystem, and mount it with ACL (Access Control Lists), which give you rights beyond the traditional read (r) write (w) and execute (x) for the 3 user groups file, owner and other.
Working With Time: What? There are 61 seconds in a minute? We can go back in time? We still tell time by the sun?
Mike Chirico, a father of triplets (all girls) lives outside of
Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters
in Computer Science and Mathematics from Villanova University, and has
worked in computer-related jobs from Wall Street to the University of
Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was
known for his open collaboration with others.
Mike's notes page is souptonuts. For
open source consulting needs, please send an email to
mchirico@gmail.com. All consulting work must include a donation to
SourceForge.net.
