SQLite

/*
** 2013-06-12
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** A shim that sits between the SQLite virtual table interface and
** runtimes with garbage collector based memory management.
*/
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <assert.h>
#include <string.h>

#ifndef SQLITE_OMIT_VIRTUALTABLE

/* Forward references */
typedef struct vtshim_aux vtshim_aux;
typedef struct vtshim_vtab vtshim_vtab;
typedef struct vtshim_cursor vtshim_cursor;


/* The vtshim_aux argument is the auxiliary parameter that is passed
** into sqlite3_create_module_v2().
*/
struct vtshim_aux {
  void *pChildAux;              /* pAux for child virtual tables */
  void (*xChildDestroy)(void*); /* Destructor for pChildAux */
  sqlite3_module *pMod;         /* Methods for child virtual tables */
  sqlite3 *db;                  /* The database to which we are attached */
  char *zName;                  /* Name of the module */
  int bDisposed;                /* True if disposed */
  vtshim_vtab *pAllVtab;        /* List of all vtshim_vtab objects */
  sqlite3_module sSelf;         /* Methods used by this shim */
};

/* A vtshim virtual table object */
struct vtshim_vtab {

/* The destructor function for a disposible module */
static void vtshimAuxDestructor(void *pXAux){
  vtshim_aux *pAux = (vtshim_aux*)pXAux;
  assert( pAux->pAllVtab==0 );
  if( !pAux->bDisposed && pAux->xChildDestroy ){
    pAux->xChildDestroy(pAux->pChildAux);
  }
  sqlite3_free(pAux->zName);
  sqlite3_free(pAux->pMod);
  sqlite3_free(pAux);
}

static int vtshimCopyModule(
  const sqlite3_module *pMod,   /* Source module to be copied */
  sqlite3_module **ppMod        /* Destination for copied module */
){
  sqlite3_module *p;
  if( !pMod || !ppMod ) return SQLITE_ERROR;
  p = sqlite3_malloc( sizeof(*p) );
  if( p==0 ) return SQLITE_NOMEM;
  memcpy(p, pMod, sizeof(*p));
  *ppMod = p;
  return SQLITE_OK;
}

#ifdef _WIN32
__declspec(dllexport)
#endif
void *sqlite3_create_disposable_module(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData,         /* Client data for xCreate/xConnect */
  void(*xDestroy)(void*)     /* Module destructor function */
){
  vtshim_aux *pAux;
  sqlite3_module *pMod;
  int rc;
  pAux = sqlite3_malloc( sizeof(*pAux) );
  if( pAux==0 ){
    if( xDestroy ) xDestroy(pClientData);
    return 0;
  }
  rc = vtshimCopyModule(p, &pMod);
  if( rc!=SQLITE_OK ){
    sqlite3_free(pAux);
    return 0;
  }
  pAux->pChildAux = pClientData;
  pAux->xChildDestroy = xDestroy;
  pAux->pMod = pMod;
  pAux->db = db;
  pAux->zName = sqlite3_mprintf("%s", zName);
  pAux->bDisposed = 0;
  pAux->pAllVtab = 0;
  pAux->sSelf.iVersion = p->iVersion<=2 ? p->iVersion : 2;
  pAux->sSelf.xCreate = p->xCreate ? vtshimCreate : 0;
  pAux->sSelf.xConnect = p->xConnect ? vtshimConnect : 0;
  pAux->sSelf.xBestIndex = p->xBestIndex ? vtshimBestIndex : 0;
  pAux->sSelf.xDisconnect = p->xDisconnect ? vtshimDisconnect : 0;
  pAux->sSelf.xDestroy = p->xDestroy ? vtshimDestroy : 0;
  pAux->sSelf.xOpen = p->xOpen ? vtshimOpen : 0;
  pAux->sSelf.xClose = p->xClose ? vtshimClose : 0;
  pAux->sSelf.xFilter = p->xFilter ? vtshimFilter : 0;
  pAux->sSelf.xNext = p->xNext ? vtshimNext : 0;
  pAux->sSelf.xEof = p->xEof ? vtshimEof : 0;
  pAux->sSelf.xColumn = p->xColumn ? vtshimColumn : 0;
  pAux->sSelf.xRowid = p->xRowid ? vtshimRowid : 0;
  pAux->sSelf.xUpdate = p->xUpdate ? vtshimUpdate : 0;
  pAux->sSelf.xBegin = p->xBegin ? vtshimBegin : 0;
  pAux->sSelf.xSync = p->xSync ? vtshimSync : 0;
  pAux->sSelf.xCommit = p->xCommit ? vtshimCommit : 0;
  pAux->sSelf.xRollback = p->xRollback ? vtshimRollback : 0;
  pAux->sSelf.xFindFunction = p->xFindFunction ? vtshimFindFunction : 0;
  pAux->sSelf.xRename = p->xRename ? vtshimRename : 0;
  if( p->iVersion>=2 ){
    pAux->sSelf.xSavepoint = p->xSavepoint ? vtshimSavepoint : 0;
    pAux->sSelf.xRelease = p->xRelease ? vtshimRelease : 0;
    pAux->sSelf.xRollbackTo = p->xRollbackTo ? vtshimRollbackTo : 0;
  }else{
    pAux->sSelf.xSavepoint = 0;
    pAux->sSelf.xRelease = 0;
    pAux->sSelf.xRollbackTo = 0;