src/lj_cdata.c

   1 /*
   2 ** C data management.
   3 ** Copyright (C) 2005-2014 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 #include "lj_obj.h"
   7
   8 #if LJ_HASFFI
   9
  10 #include "lj_gc.h"
  11 #include "lj_err.h"
  12 #include "lj_tab.h"
  13 #include "lj_ctype.h"
  14 #include "lj_cconv.h"
  15 #include "lj_cdata.h"
  16
  17 /* -- C data allocation --------------------------------------------------- */
  18
  19 /* Allocate a new C data object holding a reference to another object. */
  20 GCcdata *lj_cdata_newref(CTState *cts, const void *p, CTypeID id)
  21 {
  22   CTypeID refid = lj_ctype_intern(cts, CTINFO_REF(id), CTSIZE_PTR);
  23   GCcdata *cd = lj_cdata_new(cts, refid, CTSIZE_PTR);
  24   *(const void **)cdataptr(cd) = p;
  25   return cd;
  26 }
  27
  28 /* Allocate variable-sized or specially aligned C data object. */
  29 GCcdata *lj_cdata_newv(lua_State *L, CTypeID id, CTSize sz, CTSize align)
  30 {
  31   global_State *g;
  32   MSize extra = sizeof(GCcdataVar) + sizeof(GCcdata) +
  33                 (align > CT_MEMALIGN ? (1u<<align) - (1u<<CT_MEMALIGN) : 0);
  34   char *p = lj_mem_newt(L, extra + sz, char);
  35   uintptr_t adata = (uintptr_t)p + sizeof(GCcdataVar) + sizeof(GCcdata);
  36   uintptr_t almask = (1u << align) - 1u;
  37   GCcdata *cd = (GCcdata *)(((adata + almask) & ~almask) - sizeof(GCcdata));
  38   lua_assert((char *)cd - p < 65536);
  39   cdatav(cd)->offset = (uint16_t)((char *)cd - p);
  40   cdatav(cd)->extra = extra;
  41   cdatav(cd)->len = sz;
  42   g = G(L);
  43   setgcrefr(cd->nextgc, g->gc.root);
  44   setgcref(g->gc.root, obj2gco(cd));
  45   newwhite(g, obj2gco(cd));
  46   cd->marked |= 0x80;
  47   cd->gct = ~LJ_TCDATA;
  48   cd->ctypeid = id;
  49   return cd;
  50 }
  51
  52 /* Free a C data object. */
  53 void LJ_FASTCALL lj_cdata_free(global_State *g, GCcdata *cd)
  54 {
  55   if (LJ_UNLIKELY(cd->marked & LJ_GC_CDATA_FIN)) {
  56     GCobj *root;
  57     makewhite(g, obj2gco(cd));
  58     markfinalized(obj2gco(cd));
  59     if ((root = gcref(g->gc.mmudata)) != NULL) {
  60       setgcrefr(cd->nextgc, root->gch.nextgc);
  61       setgcref(root->gch.nextgc, obj2gco(cd));
  62       setgcref(g->gc.mmudata, obj2gco(cd));
  63     } else {
  64       setgcref(cd->nextgc, obj2gco(cd));
  65       setgcref(g->gc.mmudata, obj2gco(cd));
  66     }
  67   } else if (LJ_LIKELY(!cdataisv(cd))) {
  68     CType *ct = ctype_raw(ctype_ctsG(g), cd->ctypeid);
  69     CTSize sz = ctype_hassize(ct->info) ? ct->size : CTSIZE_PTR;
  70     lua_assert(ctype_hassize(ct->info) || ctype_isfunc(ct->info) ||
  71                ctype_isextern(ct->info));
  72     lj_mem_free(g, cd, sizeof(GCcdata) + sz);
  73   } else {
  74     lj_mem_free(g, memcdatav(cd), sizecdatav(cd));
  75   }
  76 }
  77
  78 void lj_cdata_setfin(lua_State *L, GCcdata *cd, GCobj *obj, uint32_t it)
  79 {
  80   GCtab *t = ctype_ctsG(G(L))->finalizer;
  81   if (gcref(t->metatable)) {
  82     /* Add cdata to finalizer table, if still enabled. */
  83     TValue *tv, tmp;
  84     setcdataV(L, &tmp, cd);
  85     lj_gc_anybarriert(L, t);
  86     tv = lj_tab_set(L, t, &tmp);
  87     setgcV(L, tv, obj, it);
  88     if (!tvisnil(tv))
  89       cd->marked |= LJ_GC_CDATA_FIN;
  90     else
  91       cd->marked &= ~LJ_GC_CDATA_FIN;
  92   }
  93 }
  94
  95 /* -- C data indexing ----------------------------------------------------- */
  96
  97 /* Index C data by a TValue. Return CType and pointer. */
  98 CType *lj_cdata_index(CTState *cts, GCcdata *cd, cTValue *key, uint8_t **pp,
  99                       CTInfo *qual)
 100 {
 101   uint8_t *p = (uint8_t *)cdataptr(cd);
 102   CType *ct = ctype_get(cts, cd->ctypeid);
 103   ptrdiff_t idx;
 104
 105   /* Resolve reference for cdata object. */
 106   if (ctype_isref(ct->info)) {
 107     lua_assert(ct->size == CTSIZE_PTR);
 108     p = *(uint8_t **)p;
 109     ct = ctype_child(cts, ct);
 110   }
 111
 112 collect_attrib:
 113   /* Skip attributes and collect qualifiers. */
 114   while (ctype_isattrib(ct->info)) {
 115     if (ctype_attrib(ct->info) == CTA_QUAL) *qual |= ct->size;
 116     ct = ctype_child(cts, ct);
 117   }
 118   lua_assert(!ctype_isref(ct->info));  /* Interning rejects refs to refs. */
 119
 120   if (tvisint(key)) {
 121     idx = (ptrdiff_t)intV(key);
 122     goto integer_key;
 123   } else if (tvisnum(key)) {  /* Numeric key. */
 124     idx = LJ_64 ? (ptrdiff_t)numV(key) : (ptrdiff_t)lj_num2int(numV(key));
 125   integer_key:
 126     if (ctype_ispointer(ct->info)) {
 127       CTSize sz = lj_ctype_size(cts, ctype_cid(ct->info));  /* Element size. */
 128       if (sz == CTSIZE_INVALID)
 129         lj_err_caller(cts->L, LJ_ERR_FFI_INVSIZE);
 130       if (ctype_isptr(ct->info)) {
 131         p = (uint8_t *)cdata_getptr(p, ct->size);
 132       } else if ((ct->info & (CTF_VECTOR|CTF_COMPLEX))) {
 133         if ((ct->info & CTF_COMPLEX)) idx &= 1;
 134         *qual |= CTF_CONST;  /* Valarray elements are constant. */
 135       }
 136       *pp = p + idx*(int32_t)sz;
 137       return ct;
 138     }
 139   } else if (tviscdata(key)) {  /* Integer cdata key. */
 140     GCcdata *cdk = cdataV(key);
 141     CType *ctk = ctype_raw(cts, cdk->ctypeid);
 142     if (ctype_isenum(ctk->info)) ctk = ctype_child(cts, ctk);
 143     if (ctype_isinteger(ctk->info)) {
 144       lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ctk,
 145                      (uint8_t *)&idx, cdataptr(cdk), 0);
 146       goto integer_key;
 147     }
 148   } else if (tvisstr(key)) {  /* String key. */
 149     GCstr *name = strV(key);
 150     if (ctype_isstruct(ct->info)) {
 151       CTSize ofs;
 152       CType *fct = lj_ctype_getfieldq(cts, ct, name, &ofs, qual);
 153       if (fct) {
 154         *pp = p + ofs;
 155         return fct;
 156       }
 157     } else if (ctype_iscomplex(ct->info)) {
 158       if (name->len == 2) {
 159         *qual |= CTF_CONST;  /* Complex fields are constant. */
 160         if (strdata(name)[0] == 'r' && strdata(name)[1] == 'e') {
 161           *pp = p;
 162           return ct;
 163         } else if (strdata(name)[0] == 'i' && strdata(name)[1] == 'm') {
 164           *pp = p + (ct->size >> 1);
 165           return ct;
 166         }
 167       }
 168     } else if (cd->ctypeid == CTID_CTYPEID) {
 169       /* Allow indexing a (pointer to) struct constructor to get constants. */
 170       CType *sct = ctype_raw(cts, *(CTypeID *)p);
 171       if (ctype_isptr(sct->info))
 172         sct = ctype_rawchild(cts, sct);
 173       if (ctype_isstruct(sct->info)) {
 174         CTSize ofs;
 175         CType *fct = lj_ctype_getfield(cts, sct, name, &ofs);
 176         if (fct && ctype_isconstval(fct->info))
 177           return fct;
 178       }
 179       ct = sct;  /* Allow resolving metamethods for constructors, too. */
 180     }
 181   }
 182   if (ctype_isptr(ct->info)) {  /* Automatically perform '->'. */
 183     if (ctype_isstruct(ctype_rawchild(cts, ct)->info)) {
 184       p = (uint8_t *)cdata_getptr(p, ct->size);
 185       ct = ctype_child(cts, ct);
 186       goto collect_attrib;
 187     }
 188   }
 189   *qual |= 1;  /* Lookup failed. */
 190   return ct;  /* But return the resolved raw type. */
 191 }
 192
 193 /* -- C data getters ------------------------------------------------------ */
 194
 195 /* Get constant value and convert to TValue. */
 196 static void cdata_getconst(CTState *cts, TValue *o, CType *ct)
 197 {
 198   CType *ctt = ctype_child(cts, ct);
 199   lua_assert(ctype_isinteger(ctt->info) && ctt->size <= 4);
 200   /* Constants are already zero-extended/sign-extended to 32 bits. */
 201   if ((ctt->info & CTF_UNSIGNED) && (int32_t)ct->size < 0)
 202     setnumV(o, (lua_Number)(uint32_t)ct->size);
 203   else
 204     setintV(o, (int32_t)ct->size);
 205 }
 206
 207 /* Get C data value and convert to TValue. */
 208 int lj_cdata_get(CTState *cts, CType *s, TValue *o, uint8_t *sp)
 209 {
 210   CTypeID sid;
 211
 212   if (ctype_isconstval(s->info)) {
 213     cdata_getconst(cts, o, s);
 214     return 0;  /* No GC step needed. */
 215   } else if (ctype_isbitfield(s->info)) {
 216     return lj_cconv_tv_bf(cts, s, o, sp);
 217   }
 218
 219   /* Get child type of pointer/array/field. */
 220   lua_assert(ctype_ispointer(s->info) || ctype_isfield(s->info));
 221   sid = ctype_cid(s->info);
 222   s = ctype_get(cts, sid);
 223
 224   /* Resolve reference for field. */
 225   if (ctype_isref(s->info)) {
 226     lua_assert(s->size == CTSIZE_PTR);
 227     sp = *(uint8_t **)sp;
 228     sid = ctype_cid(s->info);
 229     s = ctype_get(cts, sid);
 230   }
 231
 232   /* Skip attributes. */
 233   while (ctype_isattrib(s->info))
 234     s = ctype_child(cts, s);
 235
 236   return lj_cconv_tv_ct(cts, s, sid, o, sp);
 237 }
 238
 239 /* -- C data setters ------------------------------------------------------ */
 240
 241 /* Convert TValue and set C data value. */
 242 void lj_cdata_set(CTState *cts, CType *d, uint8_t *dp, TValue *o, CTInfo qual)
 243 {
 244   if (ctype_isconstval(d->info)) {
 245     goto err_const;
 246   } else if (ctype_isbitfield(d->info)) {
 247     if (((d->info|qual) & CTF_CONST)) goto err_const;
 248     lj_cconv_bf_tv(cts, d, dp, o);
 249     return;
 250   }
 251
 252   /* Get child type of pointer/array/field. */
 253   lua_assert(ctype_ispointer(d->info) || ctype_isfield(d->info));
 254   d = ctype_child(cts, d);
 255
 256   /* Resolve reference for field. */
 257   if (ctype_isref(d->info)) {
 258     lua_assert(d->size == CTSIZE_PTR);
 259     dp = *(uint8_t **)dp;
 260     d = ctype_child(cts, d);
 261   }
 262
 263   /* Skip attributes and collect qualifiers. */
 264   for (;;) {
 265     if (ctype_isattrib(d->info)) {
 266       if (ctype_attrib(d->info) == CTA_QUAL) qual |= d->size;
 267     } else {
 268       break;
 269     }
 270     d = ctype_child(cts, d);
 271   }
 272
 273   lua_assert(ctype_hassize(d->info) && !ctype_isvoid(d->info));
 274
 275   if (((d->info|qual) & CTF_CONST)) {
 276   err_const:
 277     lj_err_caller(cts->L, LJ_ERR_FFI_WRCONST);
 278   }
 279
 280   lj_cconv_ct_tv(cts, d, dp, o, 0);
 281 }
 282
 283 #endif