1 /*
2 ** 2014-11-10
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 SQL function eval() which runs
14 ** SQL statements recursively.
15 */
16 #include "sqlite3ext.h"
17 SQLITE_EXTENSION_INIT1
18 #include <string.h>
19
20 /*
21 ** Structure used to accumulate the output
22 */
23 struct EvalResult {
24 char *z; /* Accumulated output */
25 const char *zSep; /* Separator */
26 int szSep; /* Size of the separator string */
27 sqlite3_int64 nAlloc; /* Number of bytes allocated for z[] */
28 sqlite3_int64 nUsed; /* Number of bytes of z[] actually used */
29 };
30
31 /*
32 ** Callback from sqlite_exec() for the eval() function.
33 */
callback(void * pCtx,int argc,char ** argv,char ** colnames)34 static int callback(void *pCtx, int argc, char **argv, char **colnames){
35 struct EvalResult *p = (struct EvalResult*)pCtx;
36 int i;
37 if( argv==0 ) return 0;
38 for(i=0; i<argc; i++){
39 const char *z = argv[i] ? argv[i] : "";
40 size_t sz = strlen(z);
41 if( (sqlite3_int64)sz+p->nUsed+p->szSep+1 > p->nAlloc ){
42 char *zNew;
43 p->nAlloc = p->nAlloc*2 + sz + p->szSep + 1;
44 /* Using sqlite3_realloc64() would be better, but it is a recent
45 ** addition and will cause a segfault if loaded by an older version
46 ** of SQLite. */
47 zNew = p->nAlloc<=0x7fffffff ? sqlite3_realloc64(p->z, p->nAlloc) : 0;
48 if( zNew==0 ){
49 sqlite3_free(p->z);
50 memset(p, 0, sizeof(*p));
51 return 1;
52 }
53 p->z = zNew;
54 }
55 if( p->nUsed>0 ){
56 memcpy(&p->z[p->nUsed], p->zSep, p->szSep);
57 p->nUsed += p->szSep;
58 }
59 memcpy(&p->z[p->nUsed], z, sz);
60 p->nUsed += sz;
61 }
62 return 0;
63 }
64
65 /*
66 ** Implementation of the eval(X) and eval(X,Y) SQL functions.
67 **
68 ** Evaluate the SQL text in X. Return the results, using string
69 ** Y as the separator. If Y is omitted, use a single space character.
70 */
sqlEvalFunc(sqlite3_context * context,int argc,sqlite3_value ** argv)71 static void sqlEvalFunc(
72 sqlite3_context *context,
73 int argc,
74 sqlite3_value **argv
75 ){
76 const char *zSql;
77 sqlite3 *db;
78 char *zErr = 0;
79 int rc;
80 struct EvalResult x;
81
82 memset(&x, 0, sizeof(x));
83 x.zSep = " ";
84 zSql = (const char*)sqlite3_value_text(argv[0]);
85 if( zSql==0 ) return;
86 if( argc>1 ){
87 x.zSep = (const char*)sqlite3_value_text(argv[1]);
88 if( x.zSep==0 ) return;
89 }
90 x.szSep = (int)strlen(x.zSep);
91 db = sqlite3_context_db_handle(context);
92 rc = sqlite3_exec(db, zSql, callback, &x, &zErr);
93 if( rc!=SQLITE_OK ){
94 sqlite3_result_error(context, zErr, -1);
95 sqlite3_free(zErr);
96 }else if( x.zSep==0 ){
97 sqlite3_result_error_nomem(context);
98 sqlite3_free(x.z);
99 }else{
100 sqlite3_result_text(context, x.z, (int)x.nUsed, sqlite3_free);
101 }
102 }
103
104
105 #ifdef _WIN32
106 __declspec(dllexport)
107 #endif
sqlite3_eval_init(sqlite3 * db,char ** pzErrMsg,const sqlite3_api_routines * pApi)108 int sqlite3_eval_init(
109 sqlite3 *db,
110 char **pzErrMsg,
111 const sqlite3_api_routines *pApi
112 ){
113 int rc = SQLITE_OK;
114 SQLITE_EXTENSION_INIT2(pApi);
115 (void)pzErrMsg; /* Unused parameter */
116 rc = sqlite3_create_function(db, "eval", 1,
117 SQLITE_UTF8|SQLITE_DIRECTONLY, 0,
118 sqlEvalFunc, 0, 0);
119 if( rc==SQLITE_OK ){
120 rc = sqlite3_create_function(db, "eval", 2,
121 SQLITE_UTF8|SQLITE_DIRECTONLY, 0,
122 sqlEvalFunc, 0, 0);
123 }
124 return rc;
125 }
126