1 /*
2 ** C data management.
3 ** Copyright (C) 2005-2017 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. */
lj_cdata_newref(CTState * cts,const void * p,CTypeID id)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. */
lj_cdata_newv(lua_State * L,CTypeID id,CTSize sz,CTSize align)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 /* Allocate arbitrary C data object. */
lj_cdata_newx(CTState * cts,CTypeID id,CTSize sz,CTInfo info)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. */
lj_cdata_free(global_State * g,GCcdata * cd)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 lua_assert(ctype_hassize(ct->info) || ctype_isfunc(ct->info) ||
80 ctype_isextern(ct->info));
81 lj_mem_free(g, cd, sizeof(GCcdata) + sz);
82 } else {
83 lj_mem_free(g, memcdatav(cd), sizecdatav(cd));
84 }
85 }
86
lj_cdata_setfin(lua_State * L,GCcdata * cd,GCobj * obj,uint32_t it)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. */
lj_cdata_index(CTState * cts,GCcdata * cd,cTValue * key,uint8_t ** pp,CTInfo * qual)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 lua_assert(ct->size == CTSIZE_PTR);
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 lua_assert(!ctype_isref(ct->info)); /* Interning rejects refs to refs. */
130
131 if (tvisint(key)) {
132 idx = (ptrdiff_t)intV(key);
133 goto integer_key;
134 } else if (tvisnum(key)) { /* Numeric key. */
135 #ifdef _MSC_VER
136 /* Workaround for MSVC bug. */
137 volatile
138 #endif
139 lua_Number n = numV(key);
140 idx = LJ_64 ? (ptrdiff_t)n : (ptrdiff_t)lj_num2int(n);
141 integer_key:
142 if (ctype_ispointer(ct->info)) {
143 CTSize sz = lj_ctype_size(cts, ctype_cid(ct->info)); /* Element size. */
144 if (sz == CTSIZE_INVALID)
145 lj_err_caller(cts->L, LJ_ERR_FFI_INVSIZE);
146 if (ctype_isptr(ct->info)) {
147 p = (uint8_t *)cdata_getptr(p, ct->size);
148 } else if ((ct->info & (CTF_VECTOR|CTF_COMPLEX))) {
149 if ((ct->info & CTF_COMPLEX)) idx &= 1;
150 *qual |= CTF_CONST; /* Valarray elements are constant. */
151 }
152 *pp = p + idx*(int32_t)sz;
153 return ct;
154 }
155 } else if (tviscdata(key)) { /* Integer cdata key. */
156 GCcdata *cdk = cdataV(key);
157 CType *ctk = ctype_raw(cts, cdk->ctypeid);
158 if (ctype_isenum(ctk->info)) ctk = ctype_child(cts, ctk);
159 if (ctype_isinteger(ctk->info)) {
160 lj_cconv_ct_ct(cts, ctype_get(cts, CTID_INT_PSZ), ctk,
161 (uint8_t *)&idx, cdataptr(cdk), 0);
162 goto integer_key;
163 }
164 } else if (tvisstr(key)) { /* String key. */
165 GCstr *name = strV(key);
166 if (ctype_isstruct(ct->info)) {
167 CTSize ofs;
168 CType *fct = lj_ctype_getfieldq(cts, ct, name, &ofs, qual);
169 if (fct) {
170 *pp = p + ofs;
171 return fct;
172 }
173 } else if (ctype_iscomplex(ct->info)) {
174 if (name->len == 2) {
175 *qual |= CTF_CONST; /* Complex fields are constant. */
176 if (strdata(name)[0] == 'r' && strdata(name)[1] == 'e') {
177 *pp = p;
178 return ct;
179 } else if (strdata(name)[0] == 'i' && strdata(name)[1] == 'm') {
180 *pp = p + (ct->size >> 1);
181 return ct;
182 }
183 }
184 } else if (cd->ctypeid == CTID_CTYPEID) {
185 /* Allow indexing a (pointer to) struct constructor to get constants. */
186 CType *sct = ctype_raw(cts, *(CTypeID *)p);
187 if (ctype_isptr(sct->info))
188 sct = ctype_rawchild(cts, sct);
189 if (ctype_isstruct(sct->info)) {
190 CTSize ofs;
191 CType *fct = lj_ctype_getfield(cts, sct, name, &ofs);
192 if (fct && ctype_isconstval(fct->info))
193 return fct;
194 }
195 ct = sct; /* Allow resolving metamethods for constructors, too. */
196 }
197 }
198 if (ctype_isptr(ct->info)) { /* Automatically perform '->'. */
199 if (ctype_isstruct(ctype_rawchild(cts, ct)->info)) {
200 p = (uint8_t *)cdata_getptr(p, ct->size);
201 ct = ctype_child(cts, ct);
202 goto collect_attrib;
203 }
204 }
205 *qual |= 1; /* Lookup failed. */
206 return ct; /* But return the resolved raw type. */
207 }
208
209 /* -- C data getters ------------------------------------------------------ */
210
211 /* Get constant value and convert to TValue. */
cdata_getconst(CTState * cts,TValue * o,CType * ct)212 static void cdata_getconst(CTState *cts, TValue *o, CType *ct)
213 {
214 CType *ctt = ctype_child(cts, ct);
215 lua_assert(ctype_isinteger(ctt->info) && ctt->size <= 4);
216 /* Constants are already zero-extended/sign-extended to 32 bits. */
217 if ((ctt->info & CTF_UNSIGNED) && (int32_t)ct->size < 0)
218 setnumV(o, (lua_Number)(uint32_t)ct->size);
219 else
220 setintV(o, (int32_t)ct->size);
221 }
222
223 /* Get C data value and convert to TValue. */
lj_cdata_get(CTState * cts,CType * s,TValue * o,uint8_t * sp)224 int lj_cdata_get(CTState *cts, CType *s, TValue *o, uint8_t *sp)
225 {
226 CTypeID sid;
227
228 if (ctype_isconstval(s->info)) {
229 cdata_getconst(cts, o, s);
230 return 0; /* No GC step needed. */
231 } else if (ctype_isbitfield(s->info)) {
232 return lj_cconv_tv_bf(cts, s, o, sp);
233 }
234
235 /* Get child type of pointer/array/field. */
236 lua_assert(ctype_ispointer(s->info) || ctype_isfield(s->info));
237 sid = ctype_cid(s->info);
238 s = ctype_get(cts, sid);
239
240 /* Resolve reference for field. */
241 if (ctype_isref(s->info)) {
242 lua_assert(s->size == CTSIZE_PTR);
243 sp = *(uint8_t **)sp;
244 sid = ctype_cid(s->info);
245 s = ctype_get(cts, sid);
246 }
247
248 /* Skip attributes. */
249 while (ctype_isattrib(s->info))
250 s = ctype_child(cts, s);
251
252 return lj_cconv_tv_ct(cts, s, sid, o, sp);
253 }
254
255 /* -- C data setters ------------------------------------------------------ */
256
257 /* Convert TValue and set C data value. */
lj_cdata_set(CTState * cts,CType * d,uint8_t * dp,TValue * o,CTInfo qual)258 void lj_cdata_set(CTState *cts, CType *d, uint8_t *dp, TValue *o, CTInfo qual)
259 {
260 if (ctype_isconstval(d->info)) {
261 goto err_const;
262 } else if (ctype_isbitfield(d->info)) {
263 if (((d->info|qual) & CTF_CONST)) goto err_const;
264 lj_cconv_bf_tv(cts, d, dp, o);
265 return;
266 }
267
268 /* Get child type of pointer/array/field. */
269 lua_assert(ctype_ispointer(d->info) || ctype_isfield(d->info));
270 d = ctype_child(cts, d);
271
272 /* Resolve reference for field. */
273 if (ctype_isref(d->info)) {
274 lua_assert(d->size == CTSIZE_PTR);
275 dp = *(uint8_t **)dp;
276 d = ctype_child(cts, d);
277 }
278
279 /* Skip attributes and collect qualifiers. */
280 for (;;) {
281 if (ctype_isattrib(d->info)) {
282 if (ctype_attrib(d->info) == CTA_QUAL) qual |= d->size;
283 } else {
284 break;
285 }
286 d = ctype_child(cts, d);
287 }
288
289 lua_assert(ctype_hassize(d->info) && !ctype_isvoid(d->info));
290
291 if (((d->info|qual) & CTF_CONST)) {
292 err_const:
293 lj_err_caller(cts->L, LJ_ERR_FFI_WRCONST);
294 }
295
296 lj_cconv_ct_tv(cts, d, dp, o, 0);
297 }
298
299 #endif
300