120 lines
3.1 KiB
C
120 lines
3.1 KiB
C
/*
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** 2014-11-10
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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 SQL function eval() which runs
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** SQL statements recursively.
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*/
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#include "sqlite3ext.h"
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SQLITE_EXTENSION_INIT1
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#include <string.h>
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/*
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** Structure used to accumulate the output
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*/
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struct EvalResult {
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char *z; /* Accumulated output */
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const char *zSep; /* Separator */
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int szSep; /* Size of the separator string */
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int nAlloc; /* Number of bytes allocated for z[] */
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int nUsed; /* Number of bytes of z[] actually used */
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};
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/*
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** Callback from sqlite_exec() for the eval() function.
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*/
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static int callback(void *pCtx, int argc, char **argv, char **colnames){
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struct EvalResult *p = (struct EvalResult*)pCtx;
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int i;
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for(i=0; i<argc; i++){
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const char *z = argv[i] ? argv[i] : "";
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size_t sz = strlen(z);
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if( sz+p->nUsed+p->szSep+1 > p->nAlloc ){
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char *zNew;
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p->nAlloc = p->nAlloc*2 + sz + p->szSep + 1;
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zNew = sqlite3_realloc(p->z, p->nAlloc);
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if( zNew==0 ){
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sqlite3_free(p->z);
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memset(p, 0, sizeof(*p));
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return 1;
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}
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p->z = zNew;
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}
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if( p->nUsed>0 ){
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memcpy(&p->z[p->nUsed], p->zSep, p->szSep);
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p->nUsed += p->szSep;
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}
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memcpy(&p->z[p->nUsed], z, sz);
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p->nUsed += sz;
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}
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return 0;
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}
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/*
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** Implementation of the eval(X) and eval(X,Y) SQL functions.
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**
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** Evaluate the SQL text in X. Return the results, using string
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** Y as the separator. If Y is omitted, use a single space character.
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*/
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static void sqlEvalFunc(
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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 char *zSql;
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sqlite3 *db;
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char *zErr = 0;
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int rc;
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struct EvalResult x;
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memset(&x, 0, sizeof(x));
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x.zSep = " ";
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zSql = (const char*)sqlite3_value_text(argv[0]);
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if( zSql==0 ) return;
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if( argc>1 ){
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x.zSep = (const char*)sqlite3_value_text(argv[1]);
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if( x.zSep==0 ) return;
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}
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x.szSep = (int)strlen(x.zSep);
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db = sqlite3_context_db_handle(context);
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rc = sqlite3_exec(db, zSql, callback, &x, &zErr);
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if( rc!=SQLITE_OK ){
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sqlite3_result_error(context, zErr, -1);
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sqlite3_free(zErr);
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}else if( x.zSep==0 ){
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sqlite3_result_error_nomem(context);
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sqlite3_free(x.z);
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}else{
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sqlite3_result_text(context, x.z, x.nUsed, sqlite3_free);
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}
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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_eval_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, "eval", 1, SQLITE_UTF8, 0,
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sqlEvalFunc, 0, 0);
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if( rc==SQLITE_OK ){
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rc = sqlite3_create_function(db, "eval", 2, SQLITE_UTF8, 0,
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sqlEvalFunc, 0, 0);
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}
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return rc;
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}
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