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Lua VM wrapper
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#include <stdarg.h>
#include <string.h>
#define ERRLOG 1
#define MSGTABLE 2
#define RETOP 2
static int DATAL = 0;
struct luavm {
lua_State *L;
lua_State *dL;
};
static int
lnewvm(lua_State *L) {
struct luavm * V = lua_newuserdata(L, sizeof(struct luavm));
lua_pushvalue(L, -1);
lua_rawsetp(L, LUA_REGISTRYINDEX, &DATAL);
V->L = L;
V->dL = lua_newthread(L);
lua_setuservalue(L, -2);
lua_newtable(V->dL); // ERRLOG (1)
lua_newtable(V->dL); // MSGTABLE (2)
return 1;
}
struct luavm *
luavm_new() {
lua_State *L = luaL_newstate();
lua_pushcfunction(L, lnewvm);
if (lua_pcall(L, 0, 1, 0) != LUA_OK) {
// oom
lua_close(L);
return NULL;
}
struct luavm *V = lua_touserdata(L, -1);
lua_pop(L, 1);
return V;
}
void
luavm_close(struct luavm * V) {
if (V) {
lua_close(V->L);
}
}
static lua_State *
getthread (lua_State *L, int *arg) {
if (lua_isthread(L, 1)) {
*arg = 1;
return lua_tothread(L, 1);
}
else {
*arg = 0;
return L; /* function will operate over current thread */
}
}
static int
db_traceback (lua_State *L) {
int arg;
lua_State *L1 = getthread(L, &arg);
const char *msg = lua_tostring(L, arg + 1);
if (msg == NULL && !lua_isnoneornil(L, arg + 1)) /* non-string 'msg'? */
lua_pushvalue(L, arg + 1); /* return it untouched */
else {
int level = (int)luaL_optinteger(L, arg + 2, (L == L1) ? 1 : 0);
luaL_traceback(L, L1, msg, level);
}
return 1;
}
static const char *
pusherr(lua_State *L) {
if (lua_rawgetp(L, LUA_REGISTRYINDEX, &DATAL) != LUA_TUSERDATA) {
lua_pop(L, 1);
return "Broken VM";
}
struct luavm *V = (struct luavm *)lua_touserdata(L, -1);
lua_pop(L, 1);
lua_State *dL = V->dL;
lua_settop(dL, RETOP);
lua_xmove(L, dL, 1); // save return string
if (lua_type(dL, -1) != LUA_TSTRING) {
return "Not a string error object";
}
lua_pushvalue(dL, -1);
int n = lua_rawlen(dL, ERRLOG);
lua_rawseti(dL, ERRLOG, n + 1);
return lua_tostring(dL, -1);
}
static const char *
call_cfunction(lua_State *L, lua_CFunction f, const char * source, const char *chunkname, void *ud, int ret) {
lua_pushcfunction(L, db_traceback);
lua_pushcfunction(L, f);
lua_pushlightuserdata(L, (void *)source);
lua_pushlightuserdata(L, (void *)chunkname);
if (ud) {
lua_pushlightuserdata(L, ud);
}
if (lua_pcall(L, (ud == NULL) ? 2 : 3, ret, 1) != LUA_OK) {
return pusherr(L);
}
return NULL;
}
static int
lregister(lua_State *L) {
if (lua_rawgetp(L, LUA_REGISTRYINDEX, &DATAL) != LUA_TUSERDATA) {
return luaL_error(L, "Broken VM");
}
struct luavm *V = lua_touserdata(L, -1);
lua_pop(L, 1);
const char * source = (const char *)lua_touserdata(L, 1);
if (source == NULL) {
return luaL_error(L, "Register need source");
}
const char * chunkname = (const char *)lua_touserdata(L, 2);
if (luaL_loadbuffer(L, source, strlen(source), chunkname ? chunkname : source) != LUA_OK) {
return lua_error(L);
}
lua_call(L, 0, 1);
if (lua_type(L, -1) != LUA_TFUNCTION) {
return luaL_error(L, "Register need return a function");
}
lua_pushvalue(V->dL, MSGTABLE);
lua_xmove(V->dL, L, 1);
int n = lua_rawlen(L, -1) + 1;
lua_pushvalue(L, -2);
lua_rawseti(L, -2, n);
lua_pop(L, 1);
lua_pushinteger(L, n);
return 1;
}
const char *
luavm_register(struct luavm * V, const char * source, const char *chunkname, int *handle) {
const char * err = call_cfunction(V->L, lregister, source, chunkname, NULL, 1);
if (err)
return err;
*handle = lua_tointeger(V->L, -1);
lua_pop(V->L, 1);
return NULL;
}
static int
lpushstring(lua_State *L) {
lua_pushstring(L, (const char *)lua_touserdata(L, 1));
return 1;
}
static int
pushcstr(lua_State *L, const char *s) {
lua_pushcfunction(L, lpushstring);
lua_pushlightuserdata(L, (void *)s);
if (lua_pcall(L, 1, 1, 0) != LUA_OK) {
lua_pop(L, 1);
return 1;
}
return 0;
}
static int
pushargs(lua_State *L, const char *format, va_list ap, lua_State *dL, int *ret) {
if (format == NULL)
return 0;
int i;
for (i=0;format[i];i++) {}
if (!lua_checkstack(L, i+1)) // +1 for pushcstr
return -1;
if (ret) {
*ret = 0;
lua_settop(dL, RETOP);
if (!lua_checkstack(dL, RETOP + i + 1))
return -1;
}
int n = 0;
for (i=0;format[i];i++) {
switch(format[i]) {
case 'n': // Number
++n;
lua_pushnumber(L, va_arg(ap, double));
break;
case 'i': // Integer
++n;
lua_pushinteger(L, va_arg(ap, int));
break;
case 's': // cstring
if (pushcstr(L, va_arg(ap, const char *))) {
// oom error
lua_pop(L, n);
return -1;
}
++n;
break;
case 'b': // boolean
++n;
lua_pushboolean(L, va_arg(ap, int));
break;
case 'f': // cfunction
++n;
lua_pushcfunction(L, va_arg(ap, lua_CFunction));
break;
case 'p': // lightuserdata
++n;
lua_pushlightuserdata(L, va_arg(ap, void *));
break;
case 'N': // return Number
case 'I': // return Integer
case 'S': // return String
case 'B': // return Boolean
if (ret == NULL) {
lua_pop(L, i);
return -1;
}
lua_pushlightuserdata(dL, va_arg(ap, void *));
++*ret;
break;
default:
lua_pop(L, n);
return -1;
}
}
return n;
}
/*
void * source
void * format
va_list ap
*/
static int
linit(lua_State *L) {
luaL_openlibs(L);
const char * source = (const char *)lua_touserdata(L, 1);
if (source != NULL) {
if (luaL_loadbuffer(L, source, strlen(source), "=init") != LUA_OK) {
return lua_error(L);
}
if (lua_rawgetp(L, LUA_REGISTRYINDEX, &DATAL) != LUA_TUSERDATA) {
return luaL_error(L, "Broken VM");
}
struct luavm *V = lua_touserdata(L, -1);
lua_pop(L, 1);
lua_pushvalue(V->dL, ERRLOG);
lua_xmove(V->dL, L, 1);
const char * format = (const char *)lua_touserdata(L, 2);
va_list ap = (va_list)lua_touserdata(L, 3);
int nargs = pushargs(L, format, ap, NULL, NULL); // no return values
if (nargs < 0)
return luaL_error(L, "Invalid init arguments");
lua_call(L, 1 + nargs, 0);
}
return 0;
}
const char *
luavm_init(struct luavm *V, const char * source, const char *format, ...) {
va_list ap;
va_start(ap, format);
const char * err = call_cfunction(V->L, linit, source, format, ap, 0);
va_end(ap);
return err;
}
const char *
luavm_call(struct luavm *V, int handle, const char *format, ...) {
lua_State *L = V->L;
lua_State *dL = V->dL;
lua_settop(dL, RETOP);
if (lua_rawgeti(dL, MSGTABLE, handle) != LUA_TFUNCTION) {
lua_pop(dL, 1);
return "Invalid message function";
}
lua_pushcfunction(L, db_traceback);
lua_xmove(dL, L, 1);
// db_traceback func
va_list ap;
va_start(ap, format);
int nret = 0;
int nargs = pushargs(L, format, ap, dL, &nret);
if (nargs < 0) {
lua_pop(L, 2);
return "Invalid argument";
}
if (lua_pcall(L, nargs, nret, -2-nargs) != LUA_OK) {
return pusherr(L);
} else if (nret > 0) {
int i;
int ri = 0;
void * result;
for (i=0;format[i];i++) {
switch(format[i]) {
case 'I':
// return integer
result = lua_touserdata(dL, ++ri + RETOP);
*(int *)result = lua_tointeger(L, -nret+ri-1);
break;
case 'N':
// return number
result = lua_touserdata(dL, ++ri + RETOP);
*(double *)result = lua_tonumber(L, -nret+ri-1);
break;
case 'B':
// return boolean
result = lua_touserdata(dL, ++ri + RETOP);
*(int *)result = lua_toboolean(L, -nret+ri-1);
break;
case 'S':
// return string
result = lua_touserdata(dL, ++ri + RETOP);
lua_pushvalue(L, -nret+ri-1); // copy string ret
*(const char **)result = lua_tostring(L, -1);
lua_xmove(L, dL, 1);
lua_replace(dL, RETOP + ri); // save to dL
break;
}
}
}
return NULL;
}
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