1 /*
2 ** 2013-05-15
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 **
13 ** This SQLite extension implements a rot13() function and a rot13
14 ** collating sequence.
15 */
16 #include "sqlite3ext.h"
17 SQLITE_EXTENSION_INIT1
18 #include <assert.h>
19 #include <string.h>
20
21 /*
22 ** Perform rot13 encoding on a single ASCII character.
23 */
rot13(unsigned char c)24 static unsigned char rot13(unsigned char c){
25 if( c>='a' && c<='z' ){
26 c += 13;
27 if( c>'z' ) c -= 26;
28 }else if( c>='A' && c<='Z' ){
29 c += 13;
30 if( c>'Z' ) c -= 26;
31 }
32 return c;
33 }
34
35 /*
36 ** Implementation of the rot13() function.
37 **
38 ** Rotate ASCII alphabetic characters by 13 character positions.
39 ** Non-ASCII characters are unchanged. rot13(rot13(X)) should always
40 ** equal X.
41 */
rot13func(sqlite3_context * context,int argc,sqlite3_value ** argv)42 static void rot13func(
43 sqlite3_context *context,
44 int argc,
45 sqlite3_value **argv
46 ){
47 const unsigned char *zIn;
48 int nIn;
49 unsigned char *zOut;
50 unsigned char *zToFree = 0;
51 int i;
52 unsigned char zTemp[100];
53 assert( argc==1 );
54 if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
55 zIn = (const unsigned char*)sqlite3_value_text(argv[0]);
56 nIn = sqlite3_value_bytes(argv[0]);
57 if( nIn<sizeof(zTemp)-1 ){
58 zOut = zTemp;
59 }else{
60 zOut = zToFree = (unsigned char*)sqlite3_malloc64( nIn+1 );
61 if( zOut==0 ){
62 sqlite3_result_error_nomem(context);
63 return;
64 }
65 }
66 for(i=0; i<nIn; i++) zOut[i] = rot13(zIn[i]);
67 zOut[i] = 0;
68 sqlite3_result_text(context, (char*)zOut, i, SQLITE_TRANSIENT);
69 sqlite3_free(zToFree);
70 }
71
72 /*
73 ** Implement the rot13 collating sequence so that if
74 **
75 ** x=y COLLATE rot13
76 **
77 ** Then
78 **
79 ** rot13(x)=rot13(y) COLLATE binary
80 */
rot13CollFunc(void * notUsed,int nKey1,const void * pKey1,int nKey2,const void * pKey2)81 static int rot13CollFunc(
82 void *notUsed,
83 int nKey1, const void *pKey1,
84 int nKey2, const void *pKey2
85 ){
86 const char *zA = (const char*)pKey1;
87 const char *zB = (const char*)pKey2;
88 int i, x;
89 for(i=0; i<nKey1 && i<nKey2; i++){
90 x = (int)rot13(zA[i]) - (int)rot13(zB[i]);
91 if( x!=0 ) return x;
92 }
93 return nKey1 - nKey2;
94 }
95
96
97 #ifdef _WIN32
98 __declspec(dllexport)
99 #endif
sqlite3_rot_init(sqlite3 * db,char ** pzErrMsg,const sqlite3_api_routines * pApi)100 int sqlite3_rot_init(
101 sqlite3 *db,
102 char **pzErrMsg,
103 const sqlite3_api_routines *pApi
104 ){
105 int rc = SQLITE_OK;
106 SQLITE_EXTENSION_INIT2(pApi);
107 (void)pzErrMsg; /* Unused parameter */
108 rc = sqlite3_create_function(db, "rot13", 1,
109 SQLITE_UTF8|SQLITE_INNOCUOUS|SQLITE_DETERMINISTIC,
110 0, rot13func, 0, 0);
111 if( rc==SQLITE_OK ){
112 rc = sqlite3_create_collation(db, "rot13", SQLITE_UTF8, 0, rot13CollFunc);
113 }
114 return rc;
115 }
116