Re: Cross compiling Lua byte code

[Luiz Henrique de Figueiredo <lhf@...>]

> Hacking undump to do this should be pretty easy.

Here it is... (partially untested.)
Just be careful to build your PPC Lua with this module but your x86 Lua with
the original lundump.c.
--lhf

/*
** $Id: lundump.c,v 1.60 2006/02/16 15:53:49 lhf Exp $
** load precompiled Lua chunks
** See Copyright Notice in lua.h
*/

#include <string.h>

#define lundump_c
#define LUA_CORE

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstring.h"
#include "lundump.h"
#include "lzio.h"

typedef struct {
 lua_State* L;
 ZIO* Z;
 Mbuffer* b;
 const char* name;
 int swap;
} LoadState;

#ifdef LUAC_TRUST_BINARIES
#define IF(c,s)
#else
#define IF(c,s)		if (c) error(S,s)

static void error(LoadState* S, const char* why)
{
 luaO_pushfstring(S->L,"%s: %s in precompiled chunk",S->name,why);
 luaD_throw(S->L,LUA_ERRSYNTAX);
}
#endif

#define	LoadByte(S)		(lu_byte)LoadChar(S)
#define LoadVar(S,x)		LoadMem(S,&x,1,sizeof(x))
#define LoadVector(S,b,n,size)	LoadMem(S,b,n,size)

static void LoadBlock(LoadState* S, void* b, size_t size)
{
 size_t r=luaZ_read(S->Z,b,size);
 IF (r!=0, "unexpected end");
}

static void LoadMem (LoadState* S, void* b, int n, size_t size)
{
 LoadBlock(S,b,n*size);
 if (S->swap)
 {
  char* p=(char*) b;
  char c;
  switch (size)
  {
   case 1:
  	break;
   case 2:
	while (n--)
	{
	 c=p[0]; p[0]=p[1]; p[1]=c;
	 p+=2;
	}
  	break;
   case 4:
	while (n--)
	{
	 c=p[0]; p[0]=p[3]; p[3]=c;
	 c=p[1]; p[1]=p[2]; p[2]=c;
	 p+=4;
	}
  	break;
   case 8:
	while (n--)
	{
	 c=p[0]; p[0]=p[7]; p[7]=c;
	 c=p[1]; p[1]=p[6]; p[6]=c;
	 c=p[2]; p[2]=p[5]; p[5]=c;
	 c=p[3]; p[3]=p[4]; p[4]=c;
	 p+=8;
	}
  	break;
   default:
   	IF(1, "bad size");
  	break;
  }
 }
}

static int LoadChar(LoadState* S)
{
 char x;
 LoadVar(S,x);
 return x;
}

static int LoadInt(LoadState* S)
{
 int x;
 LoadVar(S,x);
 IF (x<0, "bad integer");
 return x;
}

static lua_Number LoadNumber(LoadState* S)
{
 double x;
 LoadVar(S,x);
 return (lua_Number) x;
}

static TString* LoadString(LoadState* S)
{
 size_t size;
 LoadVar(S,size);
 if (size==0)
  return NULL;
 else
 {
  char* s=luaZ_openspace(S->L,S->b,size);
  LoadBlock(S,s,size);
  return luaS_newlstr(S->L,s,size-1);		/* remove trailing '\0' */
 }
}

static void LoadCode(LoadState* S, Proto* f)
{
 int n=LoadInt(S);
 f->code=luaM_newvector(S->L,n,Instruction);
 f->sizecode=n;
 LoadVector(S,f->code,n,sizeof(Instruction));
}

static Proto* LoadFunction(LoadState* S, TString* p);

static void LoadConstants(LoadState* S, Proto* f)
{
 int i,n;
 n=LoadInt(S);
 f->k=luaM_newvector(S->L,n,TValue);
 f->sizek=n;
 for (i=0; i<n; i++) setnilvalue(&f->k[i]);
 for (i=0; i<n; i++)
 {
  TValue* o=&f->k[i];
  int t=LoadChar(S);
  switch (t)
  {
   case LUA_TNIL:
   	setnilvalue(o);
	break;
   case LUA_TBOOLEAN:
   	setbvalue(o,LoadChar(S));
	break;
   case LUA_TNUMBER:
	setnvalue(o,LoadNumber(S));
	break;
   case LUA_TSTRING:
	setsvalue2n(S->L,o,LoadString(S));
	break;
   default:
	IF (1, "bad constant");
	break;
  }
 }
 n=LoadInt(S);
 f->p=luaM_newvector(S->L,n,Proto*);
 f->sizep=n;
 for (i=0; i<n; i++) f->p[i]=NULL;
 for (i=0; i<n; i++) f->p[i]=LoadFunction(S,f->source);
}

static void LoadDebug(LoadState* S, Proto* f)
{
 int i,n;
 n=LoadInt(S);
 f->lineinfo=luaM_newvector(S->L,n,int);
 f->sizelineinfo=n;
 LoadVector(S,f->lineinfo,n,sizeof(int));
 n=LoadInt(S);
 f->locvars=luaM_newvector(S->L,n,LocVar);
 f->sizelocvars=n;
 for (i=0; i<n; i++) f->locvars[i].varname=NULL;
 for (i=0; i<n; i++)
 {
  f->locvars[i].varname=LoadString(S);
  f->locvars[i].startpc=LoadInt(S);
  f->locvars[i].endpc=LoadInt(S);
 }
 n=LoadInt(S);
 f->upvalues=luaM_newvector(S->L,n,TString*);
 f->sizeupvalues=n;
 for (i=0; i<n; i++) f->upvalues[i]=NULL;
 for (i=0; i<n; i++) f->upvalues[i]=LoadString(S);
}

static Proto* LoadFunction(LoadState* S, TString* p)
{
 Proto* f=luaF_newproto(S->L);
 setptvalue2s(S->L,S->L->top,f); incr_top(S->L);
 f->source=LoadString(S); if (f->source==NULL) f->source=p;
 f->linedefined=LoadInt(S);
 f->lastlinedefined=LoadInt(S);
 f->nups=LoadByte(S);
 f->numparams=LoadByte(S);
 f->is_vararg=LoadByte(S);
 f->maxstacksize=LoadByte(S);
 LoadCode(S,f);
 LoadConstants(S,f);
 LoadDebug(S,f);
 IF (!luaG_checkcode(f), "bad code");
 S->L->top--;
 return f;
}

static void LoadHeader(LoadState* S)
{
 char h[LUAC_HEADERSIZE];
 char s[LUAC_HEADERSIZE];
 luaU_header(h);
 LoadBlock(S,s,LUAC_HEADERSIZE);
 S->swap=(s[6]!=h[6]); s[6]=h[6];
 s[10]=h[10];
 IF (memcmp(h,s,LUAC_HEADERSIZE)!=0, "bad header");
}

/*
** load precompiled chunk
*/
Proto* luaU_undump (lua_State* L, ZIO* Z, Mbuffer* buff, const char* name)
{
 LoadState S;
 if (*name=='@' || *name=='=')
  S.name=name+1;
 else if (*name==LUA_SIGNATURE[0])
  S.name="binary string";
 else
  S.name=name;
 S.L=L;
 S.Z=Z;
 S.b=buff;
 LoadHeader(&S);
 return LoadFunction(&S,luaS_newliteral(L,"=?"));
}

/*
* make header
*/
void luaU_header (char* h)
{
 int x=1;
 memcpy(h,LUA_SIGNATURE,sizeof(LUA_SIGNATURE)-1);
 h+=sizeof(LUA_SIGNATURE)-1;
 *h++=(char)LUAC_VERSION;
 *h++=(char)LUAC_FORMAT;
 *h++=(char)*(char*)&x;				/* endianness */
 *h++=(char)sizeof(int);
 *h++=(char)sizeof(size_t);
 *h++=(char)sizeof(Instruction);
 *h++=(char)sizeof(lua_Number);
 *h++=(char)(((lua_Number)0.5)==0);		/* is lua_Number integral? */
}