ADDED   ext/misc/vtshim.c
Index: ext/misc/vtshim.c
==================================================================
--- /dev/null
+++ ext/misc/vtshim.c
@@ -0,0 +1,547 @@
+/*
+** 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 {
+  sqlite3_vtab base;       /* Base class - must be first */
+  sqlite3_vtab *pChild;    /* Child virtual table */
+  vtshim_aux *pAux;        /* Pointer to vtshim_aux object */
+  vtshim_cursor *pAllCur;  /* List of all cursors */
+  vtshim_vtab **ppPrev;    /* Previous on list */
+  vtshim_vtab *pNext;      /* Next on list */
+};
+
+/* A vtshim cursor object */
+struct vtshim_cursor {
+  sqlite3_vtab_cursor base;    /* Base class - must be first */
+  sqlite3_vtab_cursor *pChild; /* Cursor generated by the managed subclass */
+  vtshim_cursor **ppPrev;      /* Previous on list of all cursors */
+  vtshim_cursor *pNext;        /* Next on list of all cursors */
+};
+
+/* Macro used to copy the child vtable error message to outer vtable */
+#define VTSHIM_COPY_ERRMSG()                                             \
+  do {                                                                   \
+    sqlite3_free(pVtab->base.zErrMsg);                                   \
+    pVtab->base.zErrMsg = sqlite3_mprintf("%s", pVtab->pChild->zErrMsg); \
+  } while (0)
+
+/* Methods for the vtshim module */
+static int vtshimCreate(
+  sqlite3 *db,
+  void *ppAux,
+  int argc,
+  const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  vtshim_aux *pAux = (vtshim_aux*)ppAux;
+  vtshim_vtab *pNew;
+  int rc;
+
+  assert( db==pAux->db );
+  if( pAux->bDisposed ){
+    if( pzErr ){
+      *pzErr = sqlite3_mprintf("virtual table was disposed: \"%s\"",
+                               pAux->zName);
+    }
+    return SQLITE_ERROR;
+  }
+  pNew = sqlite3_malloc( sizeof(*pNew) );
+  *ppVtab = (sqlite3_vtab*)pNew;
+  if( pNew==0 ) return SQLITE_NOMEM;
+  memset(pNew, 0, sizeof(*pNew));
+  rc = pAux->pMod->xCreate(db, pAux->pChildAux, argc, argv,
+                           &pNew->pChild, pzErr);
+  if( rc ){
+    sqlite3_free(pNew);
+    *ppVtab = 0;
+  }
+  pNew->pAux = pAux;
+  pNew->ppPrev = &pAux->pAllVtab;
+  pNew->pNext = pAux->pAllVtab;
+  if( pAux->pAllVtab ) pAux->pAllVtab->ppPrev = &pNew->pNext;
+  pAux->pAllVtab = pNew;
+  return rc;
+}
+
+static int vtshimConnect(
+  sqlite3 *db,
+  void *ppAux,
+  int argc,
+  const char *const*argv,
+  sqlite3_vtab **ppVtab,
+  char **pzErr
+){
+  vtshim_aux *pAux = (vtshim_aux*)ppAux;
+  vtshim_vtab *pNew;
+  int rc;
+
+  assert( db==pAux->db );
+  if( pAux->bDisposed ){
+    if( pzErr ){
+      *pzErr = sqlite3_mprintf("virtual table was disposed: \"%s\"",
+                               pAux->zName);
+    }
+    return SQLITE_ERROR;
+  }
+  pNew = sqlite3_malloc( sizeof(*pNew) );
+  *ppVtab = (sqlite3_vtab*)pNew;
+  if( pNew==0 ) return SQLITE_NOMEM;
+  memset(pNew, 0, sizeof(*pNew));
+  rc = pAux->pMod->xConnect(db, pAux->pChildAux, argc, argv,
+                            &pNew->pChild, pzErr);
+  if( rc ){
+    sqlite3_free(pNew);
+    *ppVtab = 0;
+  }
+  pNew->pAux = pAux;
+  pNew->ppPrev = &pAux->pAllVtab;
+  pNew->pNext = pAux->pAllVtab;
+  if( pAux->pAllVtab ) pAux->pAllVtab->ppPrev = &pNew->pNext;
+  pAux->pAllVtab = pNew;
+  return rc;
+}
+
+static int vtshimBestIndex(
+  sqlite3_vtab *pBase,
+  sqlite3_index_info *pIdxInfo
+){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xBestIndex(pVtab->pChild, pIdxInfo);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimDisconnect(sqlite3_vtab *pBase){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc = SQLITE_OK;
+  if( !pAux->bDisposed ){
+    rc = pAux->pMod->xDisconnect(pVtab->pChild);
+  }
+  if( pVtab->pNext ) pVtab->pNext->ppPrev = pVtab->ppPrev;
+  *pVtab->ppPrev = pVtab->pNext;
+  sqlite3_free(pVtab);
+  return rc;
+}
+
+static int vtshimDestroy(sqlite3_vtab *pBase){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc = SQLITE_OK;
+  if( !pAux->bDisposed ){
+    rc = pAux->pMod->xDestroy(pVtab->pChild);
+  }
+  if( pVtab->pNext ) pVtab->pNext->ppPrev = pVtab->ppPrev;
+  *pVtab->ppPrev = pVtab->pNext;
+  sqlite3_free(pVtab);
+  return rc;
+}
+
+static int vtshimOpen(sqlite3_vtab *pBase, sqlite3_vtab_cursor **ppCursor){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  vtshim_cursor *pCur;
+  int rc;
+  *ppCursor = 0;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  pCur = sqlite3_malloc( sizeof(*pCur) );
+  if( pCur==0 ) return SQLITE_NOMEM;
+  memset(pCur, 0, sizeof(*pCur));
+  rc = pAux->pMod->xOpen(pVtab->pChild, &pCur->pChild);
+  if( rc ){
+    sqlite3_free(pCur);
+    VTSHIM_COPY_ERRMSG();
+    return rc;
+  }
+  pCur->pChild->pVtab = pVtab->pChild;
+  *ppCursor = &pCur->base;
+  pCur->ppPrev = &pVtab->pAllCur;
+  if( pVtab->pAllCur ) pVtab->pAllCur->ppPrev = &pCur->pNext;
+  pCur->pNext = pVtab->pAllCur;
+  pVtab->pAllCur = pCur;
+  return SQLITE_OK;
+}
+
+static int vtshimClose(sqlite3_vtab_cursor *pX){
+  vtshim_cursor *pCur = (vtshim_cursor*)pX;
+  vtshim_vtab *pVtab = (vtshim_vtab*)pCur->base.pVtab;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc = SQLITE_OK;
+  if( !pAux->bDisposed ){
+    rc = pAux->pMod->xClose(pCur->pChild);
+    if( rc!=SQLITE_OK ){
+      VTSHIM_COPY_ERRMSG();
+    }
+  }
+  if( pCur->pNext ) pCur->pNext->ppPrev = pCur->ppPrev;
+  *pCur->ppPrev = pCur->pNext;
+  sqlite3_free(pCur);
+  return rc;
+}
+
+static int vtshimFilter(
+  sqlite3_vtab_cursor *pX,
+  int idxNum,
+  const char *idxStr,
+  int argc,
+  sqlite3_value **argv
+){
+  vtshim_cursor *pCur = (vtshim_cursor*)pX;
+  vtshim_vtab *pVtab = (vtshim_vtab*)pCur->base.pVtab;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xFilter(pCur->pChild, idxNum, idxStr, argc, argv);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimNext(sqlite3_vtab_cursor *pX){
+  vtshim_cursor *pCur = (vtshim_cursor*)pX;
+  vtshim_vtab *pVtab = (vtshim_vtab*)pCur->base.pVtab;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xNext(pCur->pChild);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimEof(sqlite3_vtab_cursor *pX){
+  vtshim_cursor *pCur = (vtshim_cursor*)pX;
+  vtshim_vtab *pVtab = (vtshim_vtab*)pCur->base.pVtab;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return 1;
+  rc = pAux->pMod->xEof(pCur->pChild);
+  VTSHIM_COPY_ERRMSG();
+  return rc;
+}
+
+static int vtshimColumn(sqlite3_vtab_cursor *pX, sqlite3_context *ctx, int i){
+  vtshim_cursor *pCur = (vtshim_cursor*)pX;
+  vtshim_vtab *pVtab = (vtshim_vtab*)pCur->base.pVtab;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xColumn(pCur->pChild, ctx, i);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimRowid(sqlite3_vtab_cursor *pX, sqlite3_int64 *pRowid){
+  vtshim_cursor *pCur = (vtshim_cursor*)pX;
+  vtshim_vtab *pVtab = (vtshim_vtab*)pCur->base.pVtab;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xRowid(pCur->pChild, pRowid);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimUpdate(
+  sqlite3_vtab *pBase,
+  int argc,
+  sqlite3_value **argv,
+  sqlite3_int64 *pRowid
+){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xUpdate(pVtab->pChild, argc, argv, pRowid);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimBegin(sqlite3_vtab *pBase){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xBegin(pVtab->pChild);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimSync(sqlite3_vtab *pBase){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xSync(pVtab->pChild);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimCommit(sqlite3_vtab *pBase){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xCommit(pVtab->pChild);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimRollback(sqlite3_vtab *pBase){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xRollback(pVtab->pChild);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimFindFunction(
+  sqlite3_vtab *pBase,
+  int nArg,
+  const char *zName,
+  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+  void **ppArg
+){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return 0;
+  rc = pAux->pMod->xFindFunction(pVtab->pChild, nArg, zName, pxFunc, ppArg);
+  VTSHIM_COPY_ERRMSG();
+  return rc;
+}
+
+static int vtshimRename(sqlite3_vtab *pBase, const char *zNewName){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xRename(pVtab->pChild, zNewName);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimSavepoint(sqlite3_vtab *pBase, int n){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xSavepoint(pVtab->pChild, n);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimRelease(sqlite3_vtab *pBase, int n){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xRelease(pVtab->pChild, n);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+static int vtshimRollbackTo(sqlite3_vtab *pBase, int n){
+  vtshim_vtab *pVtab = (vtshim_vtab*)pBase;
+  vtshim_aux *pAux = pVtab->pAux;
+  int rc;
+  if( pAux->bDisposed ) return SQLITE_ERROR;
+  rc = pAux->pMod->xRollbackTo(pVtab->pChild, n);
+  if( rc!=SQLITE_OK ){
+    VTSHIM_COPY_ERRMSG();
+  }
+  return rc;
+}
+
+/* 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;
+  }
+  rc = sqlite3_create_module_v2(db, zName, &pAux->sSelf,
+                                pAux, vtshimAuxDestructor);
+  return rc==SQLITE_OK ? (void*)pAux : 0;
+}
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+void sqlite3_dispose_module(void *pX){
+  vtshim_aux *pAux = (vtshim_aux*)pX;
+  if( !pAux->bDisposed ){
+    vtshim_vtab *pVtab;
+    vtshim_cursor *pCur;
+    for(pVtab=pAux->pAllVtab; pVtab; pVtab=pVtab->pNext){
+      for(pCur=pVtab->pAllCur; pCur; pCur=pCur->pNext){
+        pAux->pMod->xClose(pCur->pChild);
+      }
+      pAux->pMod->xDisconnect(pVtab->pChild);
+    }
+    pAux->bDisposed = 1;
+    if( pAux->xChildDestroy ) pAux->xChildDestroy(pAux->pChildAux);
+  }
+}
+
+
+#endif /* SQLITE_OMIT_VIRTUALTABLE */
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int sqlite3_vtshim_init(
+  sqlite3 *db,
+  char **pzErrMsg,
+  const sqlite3_api_routines *pApi
+){
+  SQLITE_EXTENSION_INIT2(pApi);
+  return SQLITE_OK;
+}