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 int nAlloc; /* Number of bytes allocated for z[] */ 28 int nUsed; /* Number of bytes of z[] actually used */ 29 }; 30 31 /* 32 ** Callback from sqlite_exec() for the eval() function. 33 */ 34 static int callback(void *pCtx, int argc, char **argv, char **colnames){ 35 struct EvalResult *p = (struct EvalResult*)pCtx; 36 int i; 37 for(i=0; i<argc; i++){ 38 const char *z = argv[i] ? argv[i] : ""; 39 size_t sz = strlen(z); 40 if( sz+p->nUsed+p->szSep+1 > p->nAlloc ){ 41 char *zNew; 42 p->nAlloc = p->nAlloc*2 + sz + p->szSep + 1; 43 zNew = sqlite3_realloc(p->z, p->nAlloc); 44 if( zNew==0 ){ 45 sqlite3_free(p->z); 46 memset(p, 0, sizeof(*p)); 47 return 1; 48 } 49 p->z = zNew; 50 } 51 if( p->nUsed>0 ){ 52 memcpy(&p->z[p->nUsed], p->zSep, p->szSep); 53 p->nUsed += p->szSep; 54 } 55 memcpy(&p->z[p->nUsed], z, sz); 56 p->nUsed += sz; 57 } 58 return 0; 59 } 60 61 /* 62 ** Implementation of the eval(X) and eval(X,Y) SQL functions. 63 ** 64 ** Evaluate the SQL text in X. Return the results, using string 65 ** Y as the separator. If Y is omitted, use a single space character. 66 */ 67 static void sqlEvalFunc( 68 sqlite3_context *context, 69 int argc, 70 sqlite3_value **argv 71 ){ 72 const char *zSql; 73 sqlite3 *db; 74 char *zErr = 0; 75 int rc; 76 struct EvalResult x; 77 78 memset(&x, 0, sizeof(x)); 79 x.zSep = " "; 80 zSql = (const char*)sqlite3_value_text(argv[0]); 81 if( zSql==0 ) return; 82 if( argc>1 ){ 83 x.zSep = (const char*)sqlite3_value_text(argv[1]); 84 if( x.zSep==0 ) return; 85 } 86 x.szSep = (int)strlen(x.zSep); 87 db = sqlite3_context_db_handle(context); 88 rc = sqlite3_exec(db, zSql, callback, &x, &zErr); 89 if( rc!=SQLITE_OK ){ 90 sqlite3_result_error(context, zErr, -1); 91 sqlite3_free(zErr); 92 }else if( x.zSep==0 ){ 93 sqlite3_result_error_nomem(context); 94 sqlite3_free(x.z); 95 }else{ 96 sqlite3_result_text(context, x.z, x.nUsed, sqlite3_free); 97 } 98 } 99 100 101 #ifdef _WIN32 102 __declspec(dllexport) 103 #endif 104 int sqlite3_eval_init( 105 sqlite3 *db, 106 char **pzErrMsg, 107 const sqlite3_api_routines *pApi 108 ){ 109 int rc = SQLITE_OK; 110 SQLITE_EXTENSION_INIT2(pApi); 111 (void)pzErrMsg; /* Unused parameter */ 112 rc = sqlite3_create_function(db, "eval", 1, SQLITE_UTF8, 0, 113 sqlEvalFunc, 0, 0); 114 if( rc==SQLITE_OK ){ 115 rc = sqlite3_create_function(db, "eval", 2, SQLITE_UTF8, 0, 116 sqlEvalFunc, 0, 0); 117 } 118 return rc; 119 } 120