115 lines
2.6 KiB
C
115 lines
2.6 KiB
C
/*
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** 2013-05-15
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This SQLite extension implements a rot13() function and a rot13
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** collating sequence.
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*/
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#include "sqlite3ext.h"
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SQLITE_EXTENSION_INIT1
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#include <assert.h>
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#include <string.h>
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/*
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** Perform rot13 encoding on a single ASCII character.
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*/
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static unsigned char rot13(unsigned char c){
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if( c>='a' && c<='z' ){
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c += 13;
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if( c>'z' ) c -= 26;
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}else if( c>='A' && c<='Z' ){
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c += 13;
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if( c>'Z' ) c -= 26;
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}
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return c;
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}
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/*
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** Implementation of the rot13() function.
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**
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** Rotate ASCII alphabetic characters by 13 character positions.
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** Non-ASCII characters are unchanged. rot13(rot13(X)) should always
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** equal X.
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*/
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static void rot13func(
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sqlite3_context *context,
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int argc,
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sqlite3_value **argv
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){
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const unsigned char *zIn;
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int nIn;
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unsigned char *zOut;
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char *zToFree = 0;
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int i;
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char zTemp[100];
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assert( argc==1 );
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if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
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zIn = (const unsigned char*)sqlite3_value_text(argv[0]);
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nIn = sqlite3_value_bytes(argv[0]);
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if( nIn<sizeof(zTemp)-1 ){
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zOut = zTemp;
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}else{
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zOut = zToFree = sqlite3_malloc( nIn+1 );
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if( zOut==0 ){
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sqlite3_result_error_nomem(context);
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return;
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}
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}
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for(i=0; i<nIn; i++) zOut[i] = rot13(zIn[i]);
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zOut[i] = 0;
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sqlite3_result_text(context, (char*)zOut, i, SQLITE_TRANSIENT);
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sqlite3_free(zToFree);
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}
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/*
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** Implement the rot13 collating sequence so that if
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**
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** x=y COLLATE rot13
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**
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** Then
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**
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** rot13(x)=rot13(y) COLLATE binary
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*/
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static int rot13CollFunc(
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void *notUsed,
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int nKey1, const void *pKey1,
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int nKey2, const void *pKey2
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){
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const char *zA = (const char*)pKey1;
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const char *zB = (const char*)pKey2;
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int i, x;
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for(i=0; i<nKey1 && i<nKey2; i++){
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x = (int)rot13(zA[i]) - (int)rot13(zB[i]);
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if( x!=0 ) return x;
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}
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return nKey1 - nKey2;
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}
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#ifdef _WIN32
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__declspec(dllexport)
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#endif
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int sqlite3_rot_init(
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sqlite3 *db,
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char **pzErrMsg,
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const sqlite3_api_routines *pApi
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){
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int rc = SQLITE_OK;
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SQLITE_EXTENSION_INIT2(pApi);
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(void)pzErrMsg; /* Unused parameter */
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rc = sqlite3_create_function(db, "rot13", 1, SQLITE_UTF8, 0,
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rot13func, 0, 0);
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if( rc==SQLITE_OK ){
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rc = sqlite3_create_collation(db, "rot13", SQLITE_UTF8, 0, rot13CollFunc);
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}
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return rc;
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}
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