src/lj_cdata.c

   1 /*
   2 ** C data management.
   3 ** Copyright (C) 2005-2023 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   lj_assertL((char *)cd - p < 65536, "excessive cdata alignment");
  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 /* Allocate arbitrary C data object. */
  53 GCcdata *lj_cdata_newx(CTState *cts, CTypeID id, CTSize sz, CTInfo info)
  54 {
  55   if (!(info & CTF_VLA) && ctype_align(info) <= CT_MEMALIGN)
  56     return lj_cdata_new(cts, id, sz);
  57   else
  58     return lj_cdata_newv(cts->L, id, sz, ctype_align(info));
  59 }
  60
  61 /* Free a C data object. */
  62 void LJ_FASTCALL lj_cdata_free(global_State *g, GCcdata *cd)
  63 {
  64   if (LJ_UNLIKELY(cd->marked & LJ_GC_CDATA_FIN)) {
  65     GCobj *root;
  66     makewhite(g, obj2gco(cd));
  67     markfinalized(obj2gco(cd));
  68     if ((root = gcref(g->gc.mmudata)) != NULL) {
  69       setgcrefr(cd->nextgc, root->gch.nextgc);
  70       setgcref(root->gch.nextgc, obj2gco(cd));
  71       setgcref(g->gc.mmudata, obj2gco(cd));
  72     } else {
  73       setgcref(cd->nextgc, obj2gco(cd));
  74       setgcref(g->gc.mmudata, obj2gco(cd));
  75     }
  76   } else if (LJ_LIKELY(!cdataisv(cd))) {
  77     CType *ct = ctype_raw(ctype_ctsG(g), cd->ctypeid);
  78     CTSize sz = ctype_hassize(ct->info) ? ct->size : CTSIZE_PTR;
  79     lj_assertG(ctype_hassize(ct->info) || ctype_isfunc(ct->info) ||
  80                ctype_isextern(ct->info), "free of ctype without a size");
  81     lj_mem_free(g, cd, sizeof(GCcdata) + sz);
  82   } else {
  83     lj_mem_free(g, memcdatav(cd), sizecdatav(cd));
  84   }
  85 }
  86
  87 void lj_cdata_setfin(lua_State *L, GCcdata *cd, GCobj *obj, uint32_t it)
  88 {
  89   GCtab *t = ctype_ctsG(G(L))->finalizer;
  90   if (gcref(t->metatable)) {
  91     /* Add cdata to finalizer table, if still enabled. */
  92     TValue *tv, tmp;
  93     setcdataV(L, &tmp, cd);
  94     lj_gc_anybarriert(L, t);
  95     tv = lj_tab_set(L, t, &tmp);
  96     if (it == LJ_TNIL) {
  97       setnilV(tv);
  98       cd->marked &= ~LJ_GC_CDATA_FIN;
  99     } else {
 100       setgcV(L, tv, obj, it);
 101       cd->marked |= LJ_GC_CDATA_FIN;
 102     }
 103   }
 104 }
 105
 106 /* -- C data indexing ----------------------------------------------------- */
 107
 108 /* Index C data by a TValue. Return CType and pointer. */
 109 CType *lj_cdata_index(CTState *cts, GCcdata *cd, cTValue *key, uint8_t **pp,
 110                       CTInfo *qual)
 111 {
 112   uint8_t *p = (uint8_t *)cdataptr(cd);
 113   CType *ct = ctype_get(cts, cd->ctypeid);
 114   ptrdiff_t idx;
 115
 116   /* Resolve reference for cdata object. */
 117   if (ctype_isref(ct->info)) {
 118     lj_assertCTS(ct->size == CTSIZE_PTR, "ref is not pointer-sized");
 119     p = *(uint8_t **)p;
 120     ct = ctype_child(cts, ct);
 121   }
 122
 123 collect_attrib:
 124   /* Skip attributes and collect qualifiers. */
 125   while (ctype_isattrib(ct->info)) {
 126     if (ctype_attrib(ct->info) == CTA_QUAL) *qual |= ct->size;
 127     ct = ctype_child(cts, ct);
 128   }
 129   /* Interning rejects refs to refs. */
 130   lj_assertCTS(!ctype_isref(ct->info), "bad ref of ref");
 131
 132   if (tvisint(key)) {
 133     idx = (ptrdiff_t)intV(key);
 134     goto integer_key;
 135   } else if (tvisnum(key)) {  /* Numeric key. */
 136 #ifdef _MSC_VER
 137     /* Workaround for MSVC bug. */
 138     volatile
 139 #endif
 140     lua_Number n = numV(key);
 141     idx = LJ_64 ? (ptrdiff_t)n : (ptrdiff_t)lj_num2int(n);
 142   integer_key:
 143     if (ctype_ispointer(ct->info)) {
 144       CTSize sz = lj_ctype_size(cts, ctype_cid(ct->info));  /* Element size. */
 145       if (sz == CTSIZE_INVALID)
 146         lj_err_caller(cts->L, LJ_ERR_FFI_INVSIZE);
 147       if (ctype_isptr(ct->info)) {
 148         p = (uint8_t *)cdata_getptr(p, ct->size);
 149       } else if ((ct->info & (CTF_VECTOR|CTF_COMPLEX))) {
 150         if ((ct->info & CTF_COMPLEX)) idx &= 1;
 151         *qual |= CTF_CONST;  /* Valarray elements are constant. */
 152       }
 153       *pp = p + idx*(int32_t)sz;
 154       return ct;
 155     }
 156   } else if (tviscdata(key)) {  /* Integer cdata key. */
 157     GCcdata *cdk = cdataV(key);
 158     CType *ctk = ctype_raw(cts, cdk->ctypeid);
 159     if (ctype_isenum(ctk->info)) ctk = ctype_child(cts, ctk);
 160     if (ctype_isinteger(ctk->info)) {
 161       lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ctk,
 162                      (uint8_t *)&idx, cdataptr(cdk), 0);
 163       goto integer_key;
 164     }
 165   } else if (tvisstr(key)) {  /* String key. */
 166     GCstr *name = strV(key);
 167     if (ctype_isstruct(ct->info)) {
 168       CTSize ofs;
 169       CType *fct = lj_ctype_getfieldq(cts, ct, name, &ofs, qual);
 170       if (fct) {
 171         *pp = p + ofs;
 172         return fct;
 173       }
 174     } else if (ctype_iscomplex(ct->info)) {
 175       if (name->len == 2) {
 176         *qual |= CTF_CONST;  /* Complex fields are constant. */
 177         if (strdata(name)[0] == 'r' && strdata(name)[1] == 'e') {
 178           *pp = p;
 179           return ct;
 180         } else if (strdata(name)[0] == 'i' && strdata(name)[1] == 'm') {
 181           *pp = p + (ct->size >> 1);
 182           return ct;
 183         }
 184       }
 185     } else if (cd->ctypeid == CTID_CTYPEID) {
 186       /* Allow indexing a (pointer to) struct constructor to get constants. */
 187       CType *sct = ctype_raw(cts, *(CTypeID *)p);
 188       if (ctype_isptr(sct->info))
 189         sct = ctype_rawchild(cts, sct);
 190       if (ctype_isstruct(sct->info)) {
 191         CTSize ofs;
 192         CType *fct = lj_ctype_getfield(cts, sct, name, &ofs);
 193         if (fct && ctype_isconstval(fct->info))
 194           return fct;
 195       }
 196       ct = sct;  /* Allow resolving metamethods for constructors, too. */
 197     }
 198   }
 199   if (ctype_isptr(ct->info)) {  /* Automatically perform '->'. */
 200     if (ctype_isstruct(ctype_rawchild(cts, ct)->info)) {
 201       p = (uint8_t *)cdata_getptr(p, ct->size);
 202       ct = ctype_child(cts, ct);
 203       goto collect_attrib;
 204     }
 205   }
 206   *qual |= 1;  /* Lookup failed. */
 207   return ct;  /* But return the resolved raw type. */
 208 }
 209
 210 /* -- C data getters ------------------------------------------------------ */
 211
 212 /* Get constant value and convert to TValue. */
 213 static void cdata_getconst(CTState *cts, TValue *o, CType *ct)
 214 {
 215   CType *ctt = ctype_child(cts, ct);
 216   lj_assertCTS(ctype_isinteger(ctt->info) && ctt->size <= 4,
 217                "only 32 bit const supported");  /* NYI */
 218   /* Constants are already zero-extended/sign-extended to 32 bits. */
 219   if ((ctt->info & CTF_UNSIGNED) && (int32_t)ct->size < 0)
 220     setnumV(o, (lua_Number)(uint32_t)ct->size);
 221   else
 222     setintV(o, (int32_t)ct->size);
 223 }
 224
 225 /* Get C data value and convert to TValue. */
 226 int lj_cdata_get(CTState *cts, CType *s, TValue *o, uint8_t *sp)
 227 {
 228   CTypeID sid;
 229
 230   if (ctype_isconstval(s->info)) {
 231     cdata_getconst(cts, o, s);
 232     return 0;  /* No GC step needed. */
 233   } else if (ctype_isbitfield(s->info)) {
 234     return lj_cconv_tv_bf(cts, s, o, sp);
 235   }
 236
 237   /* Get child type of pointer/array/field. */
 238   lj_assertCTS(ctype_ispointer(s->info) || ctype_isfield(s->info),
 239                "pointer or field expected");
 240   sid = ctype_cid(s->info);
 241   s = ctype_get(cts, sid);
 242
 243   /* Resolve reference for field. */
 244   if (ctype_isref(s->info)) {
 245     lj_assertCTS(s->size == CTSIZE_PTR, "ref is not pointer-sized");
 246     sp = *(uint8_t **)sp;
 247     sid = ctype_cid(s->info);
 248     s = ctype_get(cts, sid);
 249   }
 250
 251   /* Skip attributes. */
 252   while (ctype_isattrib(s->info))
 253     s = ctype_child(cts, s);
 254
 255   return lj_cconv_tv_ct(cts, s, sid, o, sp);
 256 }
 257
 258 /* -- C data setters ------------------------------------------------------ */
 259
 260 /* Convert TValue and set C data value. */
 261 void lj_cdata_set(CTState *cts, CType *d, uint8_t *dp, TValue *o, CTInfo qual)
 262 {
 263   if (ctype_isconstval(d->info)) {
 264     goto err_const;
 265   } else if (ctype_isbitfield(d->info)) {
 266     if (((d->info|qual) & CTF_CONST)) goto err_const;
 267     lj_cconv_bf_tv(cts, d, dp, o);
 268     return;
 269   }
 270
 271   /* Get child type of pointer/array/field. */
 272   lj_assertCTS(ctype_ispointer(d->info) || ctype_isfield(d->info),
 273                "pointer or field expected");
 274   d = ctype_child(cts, d);
 275
 276   /* Resolve reference for field. */
 277   if (ctype_isref(d->info)) {
 278     lj_assertCTS(d->size == CTSIZE_PTR, "ref is not pointer-sized");
 279     dp = *(uint8_t **)dp;
 280     d = ctype_child(cts, d);
 281   }
 282
 283   /* Skip attributes and collect qualifiers. */
 284   for (;;) {
 285     if (ctype_isattrib(d->info)) {
 286       if (ctype_attrib(d->info) == CTA_QUAL) qual |= d->size;
 287     } else {
 288       break;
 289     }
 290     d = ctype_child(cts, d);
 291   }
 292
 293   lj_assertCTS(ctype_hassize(d->info), "store to ctype without size");
 294   lj_assertCTS(!ctype_isvoid(d->info), "store to void type");
 295
 296   if (((d->info|qual) & CTF_CONST)) {
 297   err_const:
 298     lj_err_caller(cts->L, LJ_ERR_FFI_WRCONST);
 299   }
 300
 301   lj_cconv_ct_tv(cts, d, dp, o, 0);
 302 }
 303
 304 #endif