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 */ 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( (sqlite3_int64)sz+p->nUsed+p->szSep+1 > p->nAlloc ){ 41 char *zNew; 42 p->nAlloc = p->nAlloc*2 + sz + p->szSep + 1; 43 /* Using sqlite3_realloc64() would be better, but it is a recent 44 ** addition and will cause a segfault if loaded by an older version 45 ** of SQLite. */ 46 zNew = p->nAlloc<=0x7fffffff ? sqlite3_realloc(p->z, (int)p->nAlloc) : 0; 47 if( zNew==0 ){ 48 sqlite3_free(p->z); 49 memset(p, 0, sizeof(*p)); 50 return 1; 51 } 52 p->z = zNew; 53 } 54 if( p->nUsed>0 ){ 55 memcpy(&p->z[p->nUsed], p->zSep, p->szSep); 56 p->nUsed += p->szSep; 57 } 58 memcpy(&p->z[p->nUsed], z, sz); 59 p->nUsed += sz; 60 } 61 return 0; 62 } 63 64 /* 65 ** Implementation of the eval(X) and eval(X,Y) SQL functions. 66 ** 67 ** Evaluate the SQL text in X. Return the results, using string 68 ** Y as the separator. If Y is omitted, use a single space character. 69 */ 70 static void sqlEvalFunc( 71 sqlite3_context *context, 72 int argc, 73 sqlite3_value **argv 74 ){ 75 const char *zSql; 76 sqlite3 *db; 77 char *zErr = 0; 78 int rc; 79 struct EvalResult x; 80 81 memset(&x, 0, sizeof(x)); 82 x.zSep = " "; 83 zSql = (const char*)sqlite3_value_text(argv[0]); 84 if( zSql==0 ) return; 85 if( argc>1 ){ 86 x.zSep = (const char*)sqlite3_value_text(argv[1]); 87 if( x.zSep==0 ) return; 88 } 89 x.szSep = (int)strlen(x.zSep); 90 db = sqlite3_context_db_handle(context); 91 rc = sqlite3_exec(db, zSql, callback, &x, &zErr); 92 if( rc!=SQLITE_OK ){ 93 sqlite3_result_error(context, zErr, -1); 94 sqlite3_free(zErr); 95 }else if( x.zSep==0 ){ 96 sqlite3_result_error_nomem(context); 97 sqlite3_free(x.z); 98 }else{ 99 sqlite3_result_text(context, x.z, (int)x.nUsed, sqlite3_free); 100 } 101 } 102 103 104 #ifdef _WIN32 105 __declspec(dllexport) 106 #endif 107 int sqlite3_eval_init( 108 sqlite3 *db, 109 char **pzErrMsg, 110 const sqlite3_api_routines *pApi 111 ){ 112 int rc = SQLITE_OK; 113 SQLITE_EXTENSION_INIT2(pApi); 114 (void)pzErrMsg; /* Unused parameter */ 115 rc = sqlite3_create_function(db, "eval", 1, SQLITE_UTF8, 0, 116 sqlEvalFunc, 0, 0); 117 if( rc==SQLITE_OK ){ 118 rc = sqlite3_create_function(db, "eval", 2, SQLITE_UTF8, 0, 119 sqlEvalFunc, 0, 0); 120 } 121 return rc; 122 } 123