cuberite-2a/lib/sqlite/lsqlite3.c

/************************************************************************
* lsqlite3                                                              *
* Copyright (C) 2002-2013 Tiago Dionizio, Doug Currie                   *
* All rights reserved.                                                  *
* Author    : Tiago Dionizio <tiago.dionizio@ist.utl.pt>                *
* Author    : Doug Currie <doug.currie@alum.mit.edu>                    *
* Library   : lsqlite3 - a SQLite 3 database binding for Lua 5          *
*                                                                       *
* Permission is hereby granted, free of charge, to any person obtaining *
* a copy of this software and associated documentation files (the       *
* "Software"), to deal in the Software without restriction, including   *
* without limitation the rights to use, copy, modify, merge, publish,   *
* distribute, sublicense, and/or sell copies of the Software, and to    *
* permit persons to whom the Software is furnished to do so, subject to *
* the following conditions:                                             *
*                                                                       *
* The above copyright notice and this permission notice shall be        *
* included in all copies or substantial portions of the Software.       *
*                                                                       *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       *
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  *
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  *
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     *
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                *
************************************************************************/
// Slightly modified by _Xoft to compile in MSVC




// 2013_04_07 _X: Added the following #define-s so that MSVC doesn't complain about non-secure stuff:
#define _CRT_SECURE_NO_WARNINGS
#ifdef __cplusplus
extern "C" {
#endif  // __cplusplus




#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define LUA_LIB
#include "lua/src/lua.h"
#include "lua/src/lauxlib.h"

#if LUA_VERSION_NUM > 501
//
// Lua 5.2
//
#define lua_strlen lua_rawlen
// luaL_typerror always used with arg at ndx == NULL
#define luaL_typerror(L,ndx,str) luaL_error(L,"bad argument %d (%s expected, got nil)",ndx,str)
// luaL_register used once, so below expansion is OK for this case
#define luaL_register(L,name,reg) lua_newtable(L);luaL_setfuncs(L,reg,0)
// luaL_openlib always used with name == NULL
#define luaL_openlib(L,name,reg,nup) luaL_setfuncs(L,reg,nup)
#endif

#include "sqlite3.h"

/* compile time features */
#if !defined(SQLITE_OMIT_PROGRESS_CALLBACK)
    #define SQLITE_OMIT_PROGRESS_CALLBACK 0
#endif
#if !defined(LSQLITE_OMIT_UPDATE_HOOK)
    #define LSQLITE_OMIT_UPDATE_HOOK 0
#endif

typedef struct sdb sdb;
typedef struct sdb_vm sdb_vm;
typedef struct sdb_func sdb_func;

/* to use as C user data so i know what function sqlite is calling */
struct sdb_func {
    /* references to associated lua values */
    int fn_step;
    int fn_finalize;
    int udata;

    sdb *db;
    char aggregate;

    sdb_func *next;
};

/* information about database */
struct sdb {
    /* associated lua state */
    lua_State *L;
    /* sqlite database handle */
    sqlite3 *db;

    /* sql functions stack usage */
    sdb_func *func;         /* top SQL function being called */

    /* references */
    int busy_cb;        /* busy callback */
    int busy_udata;

    int progress_cb;    /* progress handler */
    int progress_udata;

    int trace_cb;       /* trace callback */
    int trace_udata;

#if !defined(LSQLITE_OMIT_UPDATE_HOOK) || !LSQLITE_OMIT_UPDATE_HOOK

    int update_hook_cb; /* update_hook callback */
    int update_hook_udata;

    int commit_hook_cb; /* commit_hook callback */
    int commit_hook_udata;

    int rollback_hook_cb; /* rollback_hook callback */
    int rollback_hook_udata;

#endif
};

static const char *sqlite_meta      = ":sqlite3";
static const char *sqlite_vm_meta   = ":sqlite3:vm";
static const char *sqlite_ctx_meta  = ":sqlite3:ctx";
static int sqlite_ctx_meta_ref;

/*
** =======================================================
** Database Virtual Machine Operations
** =======================================================
*/

static void vm_push_column(lua_State *L, sqlite3_stmt *vm, int idx) {
    switch (sqlite3_column_type(vm, idx)) {
        case SQLITE_INTEGER:
            {
                sqlite_int64 i64 = sqlite3_column_int64(vm, idx);
                lua_Number n = (lua_Number)i64;
                if (n == i64)
                    lua_pushnumber(L, n);
                else
                    lua_pushlstring(L, (const char*)sqlite3_column_text(vm, idx), sqlite3_column_bytes(vm, idx));
            }
            break;
        case SQLITE_FLOAT:
            lua_pushnumber(L, sqlite3_column_double(vm, idx));
            break;
        case SQLITE_TEXT:
            lua_pushlstring(L, (const char*)sqlite3_column_text(vm, idx), sqlite3_column_bytes(vm, idx));
            break;
        case SQLITE_BLOB:
            lua_pushlstring(L, sqlite3_column_blob(vm, idx), sqlite3_column_bytes(vm, idx));
            break;
        case SQLITE_NULL:
            lua_pushnil(L);
            break;
        default:
            lua_pushnil(L);
            break;
    }
}

/* virtual machine information */
struct sdb_vm {
    sdb *db;                /* associated database handle */
    sqlite3_stmt *vm;       /* virtual machine */

    /* sqlite3_step info */
    int columns;            /* number of columns in result */
    char has_values;        /* true when step succeeds */

    char temp;              /* temporary vm used in db:rows */
};

/* called with sql text on the lua stack */
static sdb_vm *newvm(lua_State *L, sdb *db) {
    sdb_vm *svm = (sdb_vm*)lua_newuserdata(L, sizeof(sdb_vm));

    luaL_getmetatable(L, sqlite_vm_meta);
    lua_setmetatable(L, -2);        /* set metatable */

    svm->db = db;
    svm->columns = 0;
    svm->has_values = 0;
    svm->vm = NULL;
    svm->temp = 0;

    /* add an entry on the database table: svm -> sql text */
    lua_pushlightuserdata(L, db);
    lua_rawget(L, LUA_REGISTRYINDEX);
    lua_pushlightuserdata(L, svm);
    lua_pushvalue(L, -4); /* the sql text */
    lua_rawset(L, -3);
    lua_pop(L, 1);

    return svm;
}

static int cleanupvm(lua_State *L, sdb_vm *svm) {
    /* remove entry in database table - no harm if not present in the table */
    lua_pushlightuserdata(L, svm->db);
    lua_rawget(L, LUA_REGISTRYINDEX);
    lua_pushlightuserdata(L, svm);
    lua_pushnil(L);
    lua_rawset(L, -3);
    lua_pop(L, 1);

    svm->columns = 0;
    svm->has_values = 0;

    if (!svm->vm) return 0;

    lua_pushnumber(L, sqlite3_finalize(svm->vm));
    svm->vm = NULL;
    return 1;
}

static int stepvm(lua_State *L, sdb_vm *svm) {
    int result;
    int loop_limit = 3;
    while ( loop_limit-- ) {
        result = sqlite3_step(svm->vm);
        if ( result==SQLITE_ERROR ) {
          result = sqlite3_reset (svm->vm);
        }
        if ( result==SQLITE_SCHEMA ) {
            sqlite3_stmt *vn;
            const char *sql;
            /* recover sql text */
            lua_pushlightuserdata(L, svm->db);
            lua_rawget(L, LUA_REGISTRYINDEX);
            lua_pushlightuserdata(L, svm);
            lua_rawget(L, -2); /* sql text */
            sql = luaL_checkstring(L, -1);
            /* re-prepare */
            result = sqlite3_prepare(svm->db->db, sql, -1, &vn, NULL);
            if (result != SQLITE_OK) break;
            sqlite3_transfer_bindings(svm->vm, vn);
            sqlite3_finalize(svm->vm);
            svm->vm = vn;
            lua_pop(L,2);
        } else {
          break;
        }
    }
    return result;
}

static sdb_vm *lsqlite_getvm(lua_State *L, int index) {
    sdb_vm *svm = (sdb_vm*)luaL_checkudata(L, index, sqlite_vm_meta);
    if (svm == NULL) luaL_argerror(L, index, "bad sqlite virtual machine");
    return svm;
}

static sdb_vm *lsqlite_checkvm(lua_State *L, int index) {
    sdb_vm *svm = lsqlite_getvm(L, index);
    if (svm->vm == NULL) luaL_argerror(L, index, "attempt to use closed sqlite virtual machine");
    return svm;
}

static int dbvm_isopen(lua_State *L) {
    sdb_vm *svm = lsqlite_getvm(L, 1);
    lua_pushboolean(L, svm->vm != NULL ? 1 : 0);
    return 1;
}

static int dbvm_tostring(lua_State *L) {
    char buff[39];
    sdb_vm *svm = lsqlite_getvm(L, 1);
    if (svm->vm == NULL)
        strcpy(buff, "closed");
    else
        sprintf(buff, "%p", svm);
    lua_pushfstring(L, "sqlite virtual machine (%s)", buff);
    return 1;
}

static int dbvm_gc(lua_State *L) {
    sdb_vm *svm = lsqlite_getvm(L, 1);
    if (svm->vm != NULL)  /* ignore closed vms */
        cleanupvm(L, svm);
    return 0;
}

static int dbvm_step(lua_State *L) {
    int result;
    sdb_vm *svm = lsqlite_checkvm(L, 1);

    result = stepvm(L, svm);
    svm->has_values = result == SQLITE_ROW ? 1 : 0;
    svm->columns = sqlite3_data_count(svm->vm);

    lua_pushnumber(L, result);
    return 1;
}

static int dbvm_finalize(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    return cleanupvm(L, svm);
}

static int dbvm_reset(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_reset(svm->vm);
    lua_pushnumber(L, sqlite3_errcode(svm->db->db));
    return 1;
}

static void dbvm_check_contents(lua_State *L, sdb_vm *svm) {
    if (!svm->has_values) {
        luaL_error(L, "misuse of function");
    }
}

static void dbvm_check_index(lua_State *L, sdb_vm *svm, int index) {
    if (index < 0 || index >= svm->columns) {
        luaL_error(L, "index out of range [0..%d]", svm->columns - 1);
    }
}

static void dbvm_check_bind_index(lua_State *L, sdb_vm *svm, int index) {
    if (index < 1 || index > sqlite3_bind_parameter_count(svm->vm)) {
        luaL_error(L, "bind index out of range [1..%d]", sqlite3_bind_parameter_count(svm->vm));
    }
}

/*
** =======================================================
** Virtual Machine - generic info
** =======================================================
*/
static int dbvm_columns(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    lua_pushnumber(L, sqlite3_column_count(svm->vm));
    return 1;
}

/*
** =======================================================
** Virtual Machine - getters
** =======================================================
*/

static int dbvm_get_value(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    int index = luaL_checkint(L, 2);
    dbvm_check_contents(L, svm);
    dbvm_check_index(L, svm, index);
    vm_push_column(L, svm->vm, index);
    return 1;
}

static int dbvm_get_name(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    int index = (int)luaL_checknumber(L, 2);
    dbvm_check_index(L, svm, index);
    lua_pushstring(L, sqlite3_column_name(svm->vm, index));
    return 1;
}

static int dbvm_get_type(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    int index = (int)luaL_checknumber(L, 2);
    dbvm_check_index(L, svm, index);
    lua_pushstring(L, sqlite3_column_decltype(svm->vm, index));
    return 1;
}

static int dbvm_get_values(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = svm->columns;
    int n;
    dbvm_check_contents(L, svm);

    lua_newtable(L);
    for (n = 0; n < columns;) {
        vm_push_column(L, vm, n++);
        lua_rawseti(L, -2, n);
    }
    return 1;
}

static int dbvm_get_names(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = sqlite3_column_count(vm); /* valid as soon as statement prepared */
    int n;

    lua_newtable(L);
    for (n = 0; n < columns;) {
        lua_pushstring(L, sqlite3_column_name(vm, n++));
        lua_rawseti(L, -2, n);
    }
    return 1;
}

static int dbvm_get_types(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = sqlite3_column_count(vm); /* valid as soon as statement prepared */
    int n;

    lua_newtable(L);
    for (n = 0; n < columns;) {
        lua_pushstring(L, sqlite3_column_decltype(vm, n++));
        lua_rawseti(L, -2, n);
    }
    return 1;
}

static int dbvm_get_uvalues(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = svm->columns;
    int n;
    dbvm_check_contents(L, svm);

    lua_checkstack(L, columns);
    for (n = 0; n < columns; ++n)
        vm_push_column(L, vm, n);
    return columns;
}

static int dbvm_get_unames(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = sqlite3_column_count(vm); /* valid as soon as statement prepared */
    int n;

    lua_checkstack(L, columns);
    for (n = 0; n < columns; ++n)
        lua_pushstring(L, sqlite3_column_name(vm, n));
    return columns;
}

static int dbvm_get_utypes(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = sqlite3_column_count(vm); /* valid as soon as statement prepared */
    int n;

    lua_checkstack(L, columns);
    for (n = 0; n < columns; ++n)
        lua_pushstring(L, sqlite3_column_decltype(vm, n));
    return columns;
}

static int dbvm_get_named_values(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = svm->columns;
    int n;
    dbvm_check_contents(L, svm);

    lua_newtable(L);
    for (n = 0; n < columns; ++n) {
        lua_pushstring(L, sqlite3_column_name(vm, n));
        vm_push_column(L, vm, n);
        lua_rawset(L, -3);
    }
    return 1;
}

static int dbvm_get_named_types(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int columns = sqlite3_column_count(vm);
    int n;

    lua_newtable(L);
    for (n = 0; n < columns; ++n) {
        lua_pushstring(L, sqlite3_column_name(vm, n));
        lua_pushstring(L, sqlite3_column_decltype(vm, n));
        lua_rawset(L, -3);
    }
    return 1;
}

/*
** =======================================================
** Virtual Machine - Bind
** =======================================================
*/

static int dbvm_bind_index(lua_State *L, sqlite3_stmt *vm, int index, int lindex) {
    switch (lua_type(L, lindex)) {
        case LUA_TSTRING:
            return sqlite3_bind_text(vm, index, lua_tostring(L, lindex), lua_strlen(L, lindex), SQLITE_TRANSIENT);
        case LUA_TNUMBER:
            return sqlite3_bind_double(vm, index, lua_tonumber(L, lindex));
        case LUA_TBOOLEAN:
            return sqlite3_bind_int(vm, index, lua_toboolean(L, lindex) ? 1 : 0);
        case LUA_TNONE:
        case LUA_TNIL:
            return sqlite3_bind_null(vm, index);
        default:
            luaL_error(L, "index (%d) - invalid data type for bind (%s)", index, lua_typename(L, lua_type(L, lindex)));
            return SQLITE_MISUSE; /*!*/
    }
}


static int dbvm_bind_parameter_count(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    lua_pushnumber(L, sqlite3_bind_parameter_count(svm->vm));
    return 1;
}

static int dbvm_bind_parameter_name(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    int index = (int)luaL_checknumber(L, 2);
    dbvm_check_bind_index(L, svm, index);
    lua_pushstring(L, sqlite3_bind_parameter_name(svm->vm, index));
    return 1;
}

static int dbvm_bind(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int index = luaL_checkint(L, 2);
    int result;

    dbvm_check_bind_index(L, svm, index);
    result = dbvm_bind_index(L, vm, index, 3);

    lua_pushnumber(L, result);
    return 1;
}

static int dbvm_bind_blob(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    int index = luaL_checkint(L, 2);
    const char *value = luaL_checkstring(L, 3);
    int len = lua_strlen(L, 3);

    lua_pushnumber(L, sqlite3_bind_blob(svm->vm, index, value, len, SQLITE_TRANSIENT));
    return 1;
}

static int dbvm_bind_values(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int top = lua_gettop(L);
    int result, n;

    if (top - 1 != sqlite3_bind_parameter_count(vm))
        luaL_error(L,
            "incorrect number of parameters to bind (%d given, %d to bind)",
            top - 1,
            sqlite3_bind_parameter_count(vm)
        );

    for (n = 2; n <= top; ++n) {
        if ((result = dbvm_bind_index(L, vm, n - 1, n)) != SQLITE_OK) {
            lua_pushnumber(L, result);
            return 1;
        }
    }

    lua_pushnumber(L, SQLITE_OK);
    return 1;
}

static int dbvm_bind_names(lua_State *L) {
    sdb_vm *svm = lsqlite_checkvm(L, 1);
    sqlite3_stmt *vm = svm->vm;
    int count = sqlite3_bind_parameter_count(vm);
    const char *name;
    int result, n;
    luaL_checktype(L, 2, LUA_TTABLE);

    for (n = 1; n <= count; ++n) {
        name = sqlite3_bind_parameter_name(vm, n);
        if (name && (name[0] == ':' || name[0] == '$')) {
            lua_pushstring(L, ++name);
            lua_gettable(L, 2);
            result = dbvm_bind_index(L, vm, n, -1);
            lua_pop(L, 1);
        }
        else {
            lua_pushnumber(L, n);
            lua_gettable(L, 2);
            result = dbvm_bind_index(L, vm, n, -1);
            lua_pop(L, 1);
        }

        if (result != SQLITE_OK) {
            lua_pushnumber(L, result);
            return 1;
        }
    }

    lua_pushnumber(L, SQLITE_OK);
    return 1;
}

/*
** =======================================================
** Database (internal management)
** =======================================================
*/

/*
** When creating database handles, always creates a `closed' database handle
** before opening the actual database; so, if there is a memory error, the
** database is not left opened.
**
** Creates a new 'table' and leaves it in the stack
*/
static sdb *newdb (lua_State *L) {
    sdb *db = (sdb*)lua_newuserdata(L, sizeof(sdb));
    db->L = L;
    db->db = NULL;  /* database handle is currently `closed' */
    db->func = NULL;

    db->busy_cb =
    db->busy_udata =
    db->progress_cb =
    db->progress_udata =
    db->trace_cb =
    db->trace_udata = 
#if !defined(LSQLITE_OMIT_UPDATE_HOOK) || !LSQLITE_OMIT_UPDATE_HOOK
    db->update_hook_cb =
    db->update_hook_udata =
    db->commit_hook_cb =
    db->commit_hook_udata =
    db->rollback_hook_cb =
    db->rollback_hook_udata =
#endif
     LUA_NOREF;

    luaL_getmetatable(L, sqlite_meta);
    lua_setmetatable(L, -2);        /* set metatable */

    /* to keep track of 'open' virtual machines */
    lua_pushlightuserdata(L, db);
    lua_newtable(L);
    lua_rawset(L, LUA_REGISTRYINDEX);

    return db;
}

static int cleanupdb(lua_State *L, sdb *db) {
    sdb_func *func;
    sdb_func *func_next;
    int top;
    int result;

    /* free associated virtual machines */
    lua_pushlightuserdata(L, db);
    lua_rawget(L, LUA_REGISTRYINDEX);

    /* close all used handles */
    top = lua_gettop(L);
    lua_pushnil(L);
    while (lua_next(L, -2)) {
        sdb_vm *svm = lua_touserdata(L, -2); /* key: vm; val: sql text */
        cleanupvm(L, svm);

        lua_settop(L, top);
        lua_pushnil(L);
    }

    lua_pop(L, 1); /* pop vm table */

    /* remove entry in lua registry table */
    lua_pushlightuserdata(L, db);
    lua_pushnil(L);
    lua_rawset(L, LUA_REGISTRYINDEX);

    /* 'free' all references */
    luaL_unref(L, LUA_REGISTRYINDEX, db->busy_cb);
    luaL_unref(L, LUA_REGISTRYINDEX, db->busy_udata);
    luaL_unref(L, LUA_REGISTRYINDEX, db->progress_cb);
    luaL_unref(L, LUA_REGISTRYINDEX, db->progress_udata);
    luaL_unref(L, LUA_REGISTRYINDEX, db->trace_cb);
    luaL_unref(L, LUA_REGISTRYINDEX, db->trace_udata);
#if !defined(LSQLITE_OMIT_UPDATE_HOOK) || !LSQLITE_OMIT_UPDATE_HOOK
    luaL_unref(L, LUA_REGISTRYINDEX, db->update_hook_cb);
    luaL_unref(L, LUA_REGISTRYINDEX, db->update_hook_udata);
    luaL_unref(L, LUA_REGISTRYINDEX, db->commit_hook_cb);
    luaL_unref(L, LUA_REGISTRYINDEX, db->commit_hook_udata);
    luaL_unref(L, LUA_REGISTRYINDEX, db->rollback_hook_cb);
    luaL_unref(L, LUA_REGISTRYINDEX, db->rollback_hook_udata);
#endif

    /* close database */
    result = sqlite3_close(db->db);
    db->db = NULL;

    /* free associated memory with created functions */
    func = db->func;
    while (func) {
        func_next = func->next;
        luaL_unref(L, LUA_REGISTRYINDEX, func->fn_step);
        luaL_unref(L, LUA_REGISTRYINDEX, func->fn_finalize);
        luaL_unref(L, LUA_REGISTRYINDEX, func->udata);
        free(func);
        func = func_next;
    }
    db->func = NULL;
    return result;
}

static sdb *lsqlite_getdb(lua_State *L, int index) {
    sdb *db = (sdb*)luaL_checkudata(L, index, sqlite_meta);
    if (db == NULL) luaL_typerror(L, index, "sqlite database");
    return db;
}

static sdb *lsqlite_checkdb(lua_State *L, int index) {
    sdb *db = lsqlite_getdb(L, index);
    if (db->db == NULL) luaL_argerror(L, index, "attempt to use closed sqlite database");
    return db;
}


/*
** =======================================================
** User Defined Functions - Context Methods
** =======================================================
*/
typedef struct {
    sqlite3_context *ctx;
    int ud;
} lcontext;

static lcontext *lsqlite_make_context(lua_State *L) {
    lcontext *ctx = (lcontext*)lua_newuserdata(L, sizeof(lcontext));
    lua_rawgeti(L, LUA_REGISTRYINDEX, sqlite_ctx_meta_ref);
    lua_setmetatable(L, -2);
    ctx->ctx = NULL;
    ctx->ud = LUA_NOREF;
    return ctx;
}

static lcontext *lsqlite_getcontext(lua_State *L, int index) {
    lcontext *ctx = (lcontext*)luaL_checkudata(L, index, sqlite_ctx_meta);
    if (ctx == NULL) luaL_typerror(L, index, "sqlite context");
    return ctx;
}

static lcontext *lsqlite_checkcontext(lua_State *L, int index) {
    lcontext *ctx = lsqlite_getcontext(L, index);
    if (ctx->ctx == NULL) luaL_argerror(L, index, "invalid sqlite context");
    return ctx;
}

static int lcontext_tostring(lua_State *L) {
    char buff[39];
    lcontext *ctx = lsqlite_getcontext(L, 1);
    if (ctx->ctx == NULL)
        strcpy(buff, "closed");
    else
        sprintf(buff, "%p", ctx->ctx);
    lua_pushfstring(L, "sqlite function context (%s)", buff);
    return 1;
}

static void lcontext_check_aggregate(lua_State *L, lcontext *ctx) {
    sdb_func *func = (sdb_func*)sqlite3_user_data(ctx->ctx);
    if (!func->aggregate) {
        luaL_error(L, "attempt to call aggregate method from scalar function");
    }
}

static int lcontext_user_data(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    sdb_func *func = (sdb_func*)sqlite3_user_data(ctx->ctx);
    lua_rawgeti(L, LUA_REGISTRYINDEX, func->udata);
    return 1;
}

static int lcontext_get_aggregate_context(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    lcontext_check_aggregate(L, ctx);
    lua_rawgeti(L, LUA_REGISTRYINDEX, ctx->ud);
    return 1;
}

static int lcontext_set_aggregate_context(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    lcontext_check_aggregate(L, ctx);
    lua_settop(L, 2);
    luaL_unref(L, LUA_REGISTRYINDEX, ctx->ud);
    ctx->ud = luaL_ref(L, LUA_REGISTRYINDEX);
    return 0;
}

static int lcontext_aggregate_count(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    lcontext_check_aggregate(L, ctx);
    lua_pushnumber(L, sqlite3_aggregate_count(ctx->ctx));
    return 1;
}

#if 0
void *sqlite3_get_auxdata(sqlite3_context*, int);
void sqlite3_set_auxdata(sqlite3_context*, int, void*, void (*)(void*));
#endif

static int lcontext_result(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    switch (lua_type(L, 2)) {
        case LUA_TNUMBER:
            sqlite3_result_double(ctx->ctx, luaL_checknumber(L, 2));
            break;
        case LUA_TSTRING:
            sqlite3_result_text(ctx->ctx, luaL_checkstring(L, 2), lua_strlen(L, 2), SQLITE_TRANSIENT);
            break;
        case LUA_TNIL:
        case LUA_TNONE:
            sqlite3_result_null(ctx->ctx);
            break;
        default:
            luaL_error(L, "invalid result type %s", lua_typename(L, 2));
            break;
    }

    return 0;
}

static int lcontext_result_blob(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    const char *blob = luaL_checkstring(L, 2);
    int size = lua_strlen(L, 2);
    sqlite3_result_blob(ctx->ctx, (const void*)blob, size, SQLITE_TRANSIENT);
    return 0;
}

static int lcontext_result_double(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    double d = luaL_checknumber(L, 2);
    sqlite3_result_double(ctx->ctx, d);
    return 0;
}

static int lcontext_result_error(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    const char *err = luaL_checkstring(L, 2);
    int size = lua_strlen(L, 2);
    sqlite3_result_error(ctx->ctx, err, size);
    return 0;
}

static int lcontext_result_int(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    int i = luaL_checkint(L, 2);
    sqlite3_result_int(ctx->ctx, i);
    return 0;
}

static int lcontext_result_null(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    sqlite3_result_null(ctx->ctx);
    return 0;
}

static int lcontext_result_text(lua_State *L) {
    lcontext *ctx = lsqlite_checkcontext(L, 1);
    const char *text = luaL_checkstring(L, 2);
    int size = lua_strlen(L, 2);
    sqlite3_result_text(ctx->ctx, text, size, SQLITE_TRANSIENT);
    return 0;
}

/*
** =======================================================
** Database Methods
** =======================================================
*/

static int db_isopen(lua_State *L) {
    sdb *db = lsqlite_getdb(L, 1);
    lua_pushboolean(L, db->db != NULL ? 1 : 0);
    return 1;
}

static int db_last_insert_rowid(lua_State *L) {
    sdb *db = lsqlite_checkdb(L, 1);
    /* conversion warning: int64 -> luaNumber */
    sqlite_int64 rowid = sqlite3_last_insert_rowid(db->db);
    lua_Number n = (lua_Number)rowid;
    if (n == rowid)
        lua_pushnumber(L, n);
    else
        lua_pushfstring(L, "%ll", rowid);
    return 1;
}

static int db_changes(lua_State *L) {
    sdb *db = lsqlite_checkdb(L, 1);
    lua_pushnumber(L, sqlite3_changes(db->db));
    return 1;
}

static int db_total_changes(lua_State *L) {
    sdb *db = lsqlite_checkdb(L, 1);
    lua_pushnumber(L, sqlite3_total_changes(db->db));
    return 1;
}

static int db_errcode(lua_State *L) {
    sdb *db = lsqlite_checkdb(L, 1);
    lua_pushnumber(L, sqlite3_errcode(db->db));
    return 1;
}

static int db_errmsg(lua_State *L) {
    sdb *db = lsqlite_checkdb(L, 1);
    lua_pushstring(L, sqlite3_errmsg(db->db));
    return 1;
}

static int db_interrupt(lua_State *L) {
    sdb *db = lsqlite_checkdb(L, 1);
    sqlite3_interrupt(db->db);
    return 0;
}

/*
** Registering SQL functions:
*/

static void db_push_value(lua_State *L, sqlite3_value *value) {
    switch (sqlite3_value_type(value)) {
        case SQLITE_TEXT:
            lua_pushlstring(L, (const char*)sqlite3_value_text(value), sqlite3_value_bytes(value));
            break;

        case SQLITE_INTEGER:
            {
                sqlite_int64 i64 = sqlite3_value_int64(value);
                lua_Number n = (lua_Number)i64;
                if (n == i64)
                    lua_pushnumber(L, n);
                else
                    lua_pushlstring(L, (const char*)sqlite3_value_text(value), sqlite3_value_bytes(value));
            }
            break;

        case SQLITE_FLOAT:
            lua_pushnumber(L, sqlite3_value_double(value));
            break;

        case SQLITE_BLOB:
            lua_pushlstring(L, sqlite3_value_blob(value), sqlite3_value_bytes(value));
            break;

        case SQLITE_NULL:
            lua_pushnil(L);
            break;

        default:
            /* things done properly (SQLite + Lua SQLite)
            ** this should never happen */
            lua_pushnil(L);
            break;
    }
}

/*
** callback functions used when calling registered sql functions
*/

/* scalar function to be called
** callback params: context, values... */
static void db_sql_normal_function(sqlite3_context *context, int argc, sqlite3_value **argv) {
    sdb_func *func = (sdb_func*)sqlite3_user_data(context);
    lua_State *L = func->db->L;
    int n;
    lcontext *ctx;

    int top = lua_gettop(L);

    /* ensure there is enough space in the stack */
    lua_checkstack(L, argc + 3);

    lua_rawgeti(L, LUA_REGISTRYINDEX, func->fn_step);   /* function to call */

    if (!func->aggregate) {
        ctx = lsqlite_make_context(L); /* push context - used to set results */
    }
    else {
        /* reuse context userdata value */
        void *p = sqlite3_aggregate_context(context, 1);
        /* i think it is OK to use assume that using a light user data
        ** as an entry on LUA REGISTRY table will be unique */
        lua_pushlightuserdata(L, p);
        lua_rawget(L, LUA_REGISTRYINDEX);       /* context table */

        if (lua_isnil(L, -1)) { /* not yet created? */
            lua_pop(L, 1);
            ctx = lsqlite_make_context(L);
            lua_pushlightuserdata(L, p);
            lua_pushvalue(L, -2);
            lua_rawset(L, LUA_REGISTRYINDEX);
        }
        else
            ctx = lsqlite_getcontext(L, -1);
    }

    /* push params */
    for (n = 0; n < argc; ++n) {
        db_push_value(L, argv[n]);
    }

    /* set context */
    ctx->ctx = context;

    if (lua_pcall(L, argc + 1, 0, 0)) {
        const char *errmsg = lua_tostring(L, -1);
        int size = lua_strlen(L, -1);
        sqlite3_result_error(context, errmsg, size);
    }

    /* invalidate context */
    ctx->ctx = NULL;

    if (!func->aggregate) {
        luaL_unref(L, LUA_REGISTRYINDEX, ctx->ud);
    }

    lua_settop(L, top);
}

static void db_sql_finalize_function(sqlite3_context *context) {
    sdb_func *func = (sdb_func*)sqlite3_user_data(context);
    lua_State *L = func->db->L;
    void *p = sqlite3_aggregate_context(context, 1); /* minimal mem usage */
    lcontext *ctx;
    int top = lua_gettop(L);

    lua_rawgeti(L, LUA_REGISTRYINDEX, func->fn_finalize);   /* function to call */

    /* i think it is OK to use assume that using a light user data
    ** as an entry on LUA REGISTRY table will be unique */
    lua_pushlightuserdata(L, p);
    lua_rawget(L, LUA_REGISTRYINDEX);       /* context table */

    if (lua_isnil(L, -1)) { /* not yet created? - shouldn't happen in finalize function */
        lua_pop(L, 1);
        ctx = lsqlite_make_context(L);
        lua_pushlightuserdata(L, p);
        lua_pushvalue(L, -2);
        lua_rawset(L, LUA_REGISTRYINDEX);
    }
    else
        ctx = lsqlite_getcontext(L, -1);

    /* set context */
    ctx->ctx = context;

    if (lua_pcall(L, 1, 0, 0)) {
        sqlite3_result_error(context, lua_tostring(L, -1), -1);
    }

    /* invalidate context */
    ctx->ctx = NULL;

    /* cleanup context */
    luaL_unref(L, LUA_REGISTRYINDEX, ctx->ud);
    /* remove it from registry */
    lua_pushlightuserdata(L, p);
    lua_pushnil(L);
    lua_rawset(L, LUA_REGISTRYINDEX);

    lua_settop(L, top);
}

/*
** Register a normal function
** Params: db, function name, number arguments, [ callback | step, finalize], user data
** Returns: true on sucess
**
** Normal function:
** Params: context, params
**
** Aggregate function:
** Params of step: context, params
** Params of finalize: context
*/
static int db_register_function(lua_State *L, int aggregate) {
    sdb *db = lsqlite_checkdb(L, 1);
    const char *name;
    int args;
    int result;
    sdb_func *func;

    /* safety measure */
    if (aggregate) aggregate = 1;

    name = luaL_checkstring(L, 2);