Re: LuaTeX incompatible with Lua

[Henri Menke <henrimenke@gmail.com>]

Below I include a suggestion on how to do this sort of version agnostic.

Cheers, Henri

Live example on Wandbox:

     https://wandbox.org/permlink/jEn9kNnPB0t5rwjP

---

#include <lauxlib.h>
#include <lua.h>
#include <lualib.h>

#include <assert.h>
#include <stdio.h>

static int (*lua_os_execute)(lua_State *L) = NULL;

static int os_execute(lua_State *L) {
     // Do whatever
     printf("Hello Hans!\n");

     // Safeguard
     assert(lua_os_execute != NULL);

     // Return wrapped
     return lua_os_execute(L);
}

LUAMOD_API int luaopen_oslibext(lua_State *L) {
     lua_getglobal(L, "os");

     // Get the address of the original function
     if (lua_os_execute == NULL) {
         lua_getfield(L, -1, "execute");
         lua_os_execute = lua_tocfunction(L, -1);
         lua_pop(L, 1);
     }

     // Push the new function to overwrite the old one
     lua_pushcfunction(L, os_execute);
     lua_setfield(L, -2, "execute");
     return 1;
}

int main(void) {
     lua_State *L = luaL_newstate();
     luaL_openlibs(L);
     luaopen_oslibext(L);

     if (luaL_dostring(L, "os.execute([[date]])") != 0) {
         fprintf(stderr, "%s", lua_tostring(L, -1));
         lua_pop(L, 1);
     }

     lua_close(L);
}

On 11/21/19 8:17 PM, Henri Menke wrote:
> Dear list,
> 
> The following Lua script behaves differently when executed in Lua vs.
> LuaTeX.
> 
>       print(os.execute("date"))
> 
> It seems that the definition of os_execute in loslibext.c was copied
> over from Lua 5.1 and not adapted to newer versions.
> 
>       $ lua5.1 test.lua
>       0
>       $ lua5.2 test.lua
>       true	exit	0
>       $ lua5.3 test.lua
>       true	exit	0
>       $ texlua test.lua
>       0
>       $ luajit test.lua
>       0
>       $ texluajit test.lua
>       0
> 
> As you can see from the example, this comes with the additional
> complication that LuaJIT has Lua 5.1 behaviour and should also retain
> that.
> 
> Cheers, Henri
> 
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