/*
** 2013-05-15
**
** 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.
**
******************************************************************************
**
** This SQLite extension implements a rot13() function and a rot13
** collating sequence.
*/
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <assert.h>
#include <string.h>
/*
** Perform rot13 encoding on a single ASCII character.
*/
static unsigned char rot13(unsigned char c){
if( c>='a' && c<='z' ){
c += 13;
if( c>'z' ) c -= 26;
}else if( c>='A' && c<='Z' ){
c += 13;
if( c>'Z' ) c -= 26;
}
return c;
}
/*
** Implementation of the rot13() function.
**
** Rotate ASCII alphabetic characters by 13 character positions.
** Non-ASCII characters are unchanged. rot13(rot13(X)) should always
** equal X.
*/
static void rot13func(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
const unsigned char *zIn;
int nIn;
unsigned char *zOut;
char *zToFree = 0;
int i;
char zTemp[100];
assert( argc==1 );
if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
zIn = (const unsigned char*)sqlite3_value_text(argv[0]);
nIn = sqlite3_value_bytes(argv[0]);
if( nIn<sizeof(zTemp)-1 ){
zOut = zTemp;
}else{
zOut = zToFree = sqlite3_malloc( nIn+1 );
if( zOut==0 ){
sqlite3_result_error_nomem(context);
return;
}
}
for(i=0; i<nIn; i++) zOut[i] = rot13(zIn[i]);
zOut[i] = 0;
sqlite3_result_text(context, (char*)zOut, i, SQLITE_TRANSIENT);
sqlite3_free(zToFree);
}
/*
** Implement the rot13 collating sequence so that if
**
** x=y COLLATE rot13
**
** Then
**
** rot13(x)=rot13(y) COLLATE binary
*/
static int rot13CollFunc(
void *notUsed,
int nKey1, const void *pKey1,
int nKey2, const void *pKey2
){
const char *zA = (const char*)pKey1;
const char *zB = (const char*)pKey2;
int i, x;
for(i=0; i<nKey1 && i<nKey2; i++){
x = (int)rot13(zA[i]) - (int)rot13(zB[i]);
if( x!=0 ) return x;
}
return nKey1 - nKey2;
}
#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_rot_init(
sqlite3 *db,
char **pzErrMsg,
const sqlite3_api_routines *pApi
){
int rc = SQLITE_OK;
SQLITE_EXTENSION_INIT2(pApi);
(void)pzErrMsg; /* Unused parameter */
rc = sqlite3_create_function(db, "rot13", 1, SQLITE_UTF8, 0,
rot13func, 0, 0);
if( rc==SQLITE_OK ){
rc = sqlite3_create_collation(db, "rot13", SQLITE_UTF8, 0, rot13CollFunc);
}
return rc;
}