LuaTeX incompatible with Lua

LuaTeX incompatible with Lua

[Henri Menke]

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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Re: LuaTeX incompatible with Lua

[Henri Menke]

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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___________________________________________________________________________________

Re: LuaTeX incompatible with Lua

[Hans Hagen]

On 11/21/2019 8:17 AM, 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.
Indeed, the old interface was kept (also for compatibility reasons as 
lua is used for scripts in texlive etc).

If one used lua as well as luatex as lua engine for the same script one 
can write a wrapper if needed (I have been thinking of that on context 
but again it would also mean adapting older scripts laying around.)

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________