lua/ldump.c

/*
** $Id: ldump.c $
** save precompiled Lua chunks
** See Copyright Notice in lua.h
*/

#define ldump_c
#define LUA_CORE

#include "lprefix.h"


#include <limits.h>
#include <stddef.h>

#include "lua.h"

#include "lgc.h"
#include "lobject.h"
#include "lstate.h"
#include "ltable.h"
#include "lundump.h"


typedef struct {
  lua_State *L;
  lua_Writer writer;
  void *data;
  lu_mem offset;  /* current position relative to beginning of dump */
  int strip;
  int status;
  Table *h;  /* table to track saved strings */
  lua_Integer nstr;  /* counter to number saved strings */
} DumpState;


/*
** All high-level dumps go through dumpVector; you can change it to
** change the endianness of the result
*/
#define dumpVector(D,v,n)	dumpBlock(D,v,(n)*sizeof((v)[0]))

#define dumpLiteral(D, s)	dumpBlock(D,s,sizeof(s) - sizeof(char))


static void dumpBlock (DumpState *D, const void *b, size_t size) {
  if (D->status == 0 && size > 0) {
    lua_unlock(D->L);
    D->status = (*D->writer)(D->L, b, size, D->data);
    lua_lock(D->L);
    D->offset += size;
  }
}


static void dumpAlign (DumpState *D, int align) {
  int padding = align - (D->offset % align);
  if (padding < align) {  /* apd == align means no padding */
    static lua_Integer paddingContent = 0;
    dumpBlock(D, &paddingContent, padding);
    lua_assert(D->offset % align == 0);
  }
}


#define dumpVar(D,x)		dumpVector(D,&x,1)


static void dumpByte (DumpState *D, int y) {
  lu_byte x = (lu_byte)y;
  dumpVar(D, x);
}


/*
** 'dumpSize' buffer size: each byte can store up to 7 bits. (The "+6"
** rounds up the division.)
*/
#define DIBS    ((sizeof(size_t) * CHAR_BIT + 6) / 7)

static void dumpSize (DumpState *D, size_t x) {
  lu_byte buff[DIBS];
  int n = 0;
  do {
    buff[DIBS - (++n)] = x & 0x7f;  /* fill buffer in reverse order */
    x >>= 7;
  } while (x != 0);
  buff[DIBS - 1] |= 0x80;  /* mark last byte */
  dumpVector(D, buff + DIBS - n, n);
}


static void dumpInt (DumpState *D, int x) {
  dumpSize(D, x);
}


static void dumpNumber (DumpState *D, lua_Number x) {
  dumpVar(D, x);
}


static void dumpInteger (DumpState *D, lua_Integer x) {
  dumpVar(D, x);
}


/*
** Dump a String. First dump its "size": size==0 means NULL;
** size==1 is followed by an index and means "reuse saved string with
** that index"; size>=2 is followed by the string contents with real
** size==size-2 and means that string, which will be saved with
** the next available index.
*/
static void dumpString (DumpState *D, TString *s) {
  if (s == NULL)
    dumpSize(D, 0);
  else {
    const TValue *idx = luaH_getstr(D->h, s);
    if (ttisinteger(idx)) {  /* string already saved? */
      dumpSize(D, 1);  /* reuse a saved string */
      dumpInt(D, ivalue(idx));  /* index of saved string */
    }
    else {  /* must write and save the string */
      TValue key, value;  /* to save the string in the hash */
      size_t size = tsslen(s);
      dumpSize(D, size + 2);
      dumpVector(D, getstr(s), size);
      D->nstr++;  /* one more saved string */
      setsvalue(D->L, &key, s);  /* the string is the key */
      setivalue(&value, D->nstr);  /* its index is the value */
      luaH_finishset(D->L, D->h, &key, idx, &value);  /* h[s] = nstr */
      /* integer value does not need barrier */
    }
  }
}


static void dumpCode (DumpState *D, const Proto *f) {
  dumpInt(D, f->sizecode);
  dumpAlign(D, sizeof(f->code[0]));
  dumpVector(D, f->code, f->sizecode);
}


static void dumpFunction(DumpState *D, const Proto *f);

static void dumpConstants (DumpState *D, const Proto *f) {
  int i;
  int n = f->sizek;
  dumpInt(D, n);
  for (i = 0; i < n; i++) {
    const TValue *o = &f->k[i];
    int tt = ttypetag(o);
    dumpByte(D, tt);
    switch (tt) {
      case LUA_VNUMFLT:
        dumpNumber(D, fltvalue(o));
        break;
      case LUA_VNUMINT:
        dumpInteger(D, ivalue(o));
        break;
      case LUA_VSHRSTR:
      case LUA_VLNGSTR:
        dumpString(D, tsvalue(o));
        break;
      default:
        lua_assert(tt == LUA_VNIL || tt == LUA_VFALSE || tt == LUA_VTRUE);
    }
  }
}


static void dumpProtos (DumpState *D, const Proto *f) {
  int i;
  int n = f->sizep;
  dumpInt(D, n);
  for (i = 0; i < n; i++)
    dumpFunction(D, f->p[i]);
}


static void dumpUpvalues (DumpState *D, const Proto *f) {
  int i, n = f->sizeupvalues;
  dumpInt(D, n);
  for (i = 0; i < n; i++) {
    dumpByte(D, f->upvalues[i].instack);
    dumpByte(D, f->upvalues[i].idx);
    dumpByte(D, f->upvalues[i].kind);
  }
}


static void dumpDebug (DumpState *D, const Proto *f) {
  int i, n;
  n = (D->strip) ? 0 : f->sizelineinfo;
  dumpInt(D, n);
  dumpVector(D, f->lineinfo, n);
  n = (D->strip) ? 0 : f->sizeabslineinfo;
  dumpInt(D, n);
  for (i = 0; i < n; i++) {
    dumpInt(D, f->abslineinfo[i].pc);
    dumpInt(D, f->abslineinfo[i].line);
  }
  n = (D->strip) ? 0 : f->sizelocvars;
  dumpInt(D, n);
  for (i = 0; i < n; i++) {
    dumpString(D, f->locvars[i].varname);
    dumpInt(D, f->locvars[i].startpc);
    dumpInt(D, f->locvars[i].endpc);
  }
  n = (D->strip) ? 0 : f->sizeupvalues;
  dumpInt(D, n);
  for (i = 0; i < n; i++)
    dumpString(D, f->upvalues[i].name);
}


static void dumpFunction (DumpState *D, const Proto *f) {
  if (D->strip)
    dumpString(D, NULL);  /* no debug info */
  else
    dumpString(D, f->source);
  dumpInt(D, f->linedefined);
  dumpInt(D, f->lastlinedefined);
  dumpByte(D, f->numparams);
  dumpByte(D, f->is_vararg);
  dumpByte(D, f->maxstacksize);
  dumpCode(D, f);
  dumpConstants(D, f);
  dumpUpvalues(D, f);
  dumpProtos(D, f);
  dumpDebug(D, f);
}


static void dumpHeader (DumpState *D) {
  dumpLiteral(D, LUA_SIGNATURE);
  dumpByte(D, LUAC_VERSION);
  dumpByte(D, LUAC_FORMAT);
  dumpLiteral(D, LUAC_DATA);
  dumpByte(D, sizeof(Instruction));
  dumpByte(D, sizeof(lua_Integer));
  dumpByte(D, sizeof(lua_Number));
  dumpInteger(D, LUAC_INT);
  dumpNumber(D, LUAC_NUM);
}


/*
** dump Lua function as precompiled chunk
*/
int luaU_dump(lua_State *L, const Proto *f, lua_Writer w, void *data,
              int strip, Table *h) {
  DumpState D;
  D.L = L;
  D.writer = w;
  D.offset = 0;
  D.data = data;
  D.strip = strip;
  D.status = 0;
  D.h = h;
  D.nstr = 0;
  dumpHeader(&D);
  dumpByte(&D, f->sizeupvalues);
  dumpFunction(&D, f);
  return D.status;
}