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1 /*
2 ** $Id: lstate.h,v 2.133.1.1 2017/04/19 17:39:34 roberto Exp $
3 ** Global State
4 ** See Copyright Notice in lua.h
5 */
6 
7 #ifndef lstate_h
8 #define lstate_h
9 
10 #include "lua.h"
11 
12 #include "lobject.h"
13 #include "ltm.h"
14 #include "lzio.h"
15 
16 
17 /*
18 
19 ** Some notes about garbage-collected objects: All objects in Lua must
20 ** be kept somehow accessible until being freed, so all objects always
21 ** belong to one (and only one) of these lists, using field 'next' of
22 ** the 'CommonHeader' for the link:
23 **
24 ** 'allgc': all objects not marked for finalization;
25 ** 'finobj': all objects marked for finalization;
26 ** 'tobefnz': all objects ready to be finalized;
27 ** 'fixedgc': all objects that are not to be collected (currently
28 ** only small strings, such as reserved words).
29 **
30 ** Moreover, there is another set of lists that control gray objects.
31 ** These lists are linked by fields 'gclist'. (All objects that
32 ** can become gray have such a field. The field is not the same
33 ** in all objects, but it always has this name.)  Any gray object
34 ** must belong to one of these lists, and all objects in these lists
35 ** must be gray:
36 **
37 ** 'gray': regular gray objects, still waiting to be visited.
38 ** 'grayagain': objects that must be revisited at the atomic phase.
39 **   That includes
40 **   - black objects got in a write barrier;
41 **   - all kinds of weak tables during propagation phase;
42 **   - all threads.
43 ** 'weak': tables with weak values to be cleared;
44 ** 'ephemeron': ephemeron tables with white->white entries;
45 ** 'allweak': tables with weak keys and/or weak values to be cleared.
46 ** The last three lists are used only during the atomic phase.
47 
48 */
49 
50 
51 struct lua_longjmp;  /* defined in ldo.c */
52 
53 
54 /*
55 ** Atomic type (relative to signals) to better ensure that 'lua_sethook'
56 ** is thread safe
57 */
58 #if !defined(l_signalT)
59 #include <signal.h>
60 #define l_signalT	sig_atomic_t
61 #endif
62 
63 
64 /* extra stack space to handle TM calls and some other extras */
65 #define EXTRA_STACK   5
66 
67 
68 #define BASIC_STACK_SIZE        (2*LUA_MINSTACK)
69 
70 
71 /* kinds of Garbage Collection */
72 #define KGC_NORMAL	0
73 #define KGC_EMERGENCY	1	/* gc was forced by an allocation failure */
74 
75 
76 typedef struct stringtable {
77   TString **hash;
78   int nuse;  /* number of elements */
79   int size;
80 } stringtable;
81 
82 
83 /*
84 ** Information about a call.
85 ** When a thread yields, 'func' is adjusted to pretend that the
86 ** top function has only the yielded values in its stack; in that
87 ** case, the actual 'func' value is saved in field 'extra'.
88 ** When a function calls another with a continuation, 'extra' keeps
89 ** the function index so that, in case of errors, the continuation
90 ** function can be called with the correct top.
91 */
92 typedef struct CallInfo {
93   StkId func;  /* function index in the stack */
94   StkId	top;  /* top for this function */
95   struct CallInfo *previous, *next;  /* dynamic call link */
96   union {
97     struct {  /* only for Lua functions */
98       StkId base;  /* base for this function */
99       const Instruction *savedpc;
100     } l;
101     struct {  /* only for C functions */
102       lua_KFunction k;  /* continuation in case of yields */
103       ptrdiff_t old_errfunc;
104       lua_KContext ctx;  /* context info. in case of yields */
105     } c;
106   } u;
107   ptrdiff_t extra;
108   short nresults;  /* expected number of results from this function */
109   unsigned short callstatus;
110 } CallInfo;
111 
112 
113 /*
114 ** Bits in CallInfo status
115 */
116 #define CIST_OAH	(1<<0)	/* original value of 'allowhook' */
117 #define CIST_LUA	(1<<1)	/* call is running a Lua function */
118 #define CIST_HOOKED	(1<<2)	/* call is running a debug hook */
119 #define CIST_FRESH	(1<<3)	/* call is running on a fresh invocation
120                                    of luaV_execute */
121 #define CIST_YPCALL	(1<<4)	/* call is a yieldable protected call */
122 #define CIST_TAIL	(1<<5)	/* call was tail called */
123 #define CIST_HOOKYIELD	(1<<6)	/* last hook called yielded */
124 #define CIST_LEQ	(1<<7)  /* using __lt for __le */
125 #define CIST_FIN	(1<<8)  /* call is running a finalizer */
126 
127 #define isLua(ci)	((ci)->callstatus & CIST_LUA)
128 
129 /* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
130 #define setoah(st,v)	((st) = ((st) & ~CIST_OAH) | (v))
131 #define getoah(st)	((st) & CIST_OAH)
132 
133 
134 /*
135 ** 'global state', shared by all threads of this state
136 */
137 typedef struct global_State {
138   lua_Alloc frealloc;  /* function to reallocate memory */
139   void *ud;         /* auxiliary data to 'frealloc' */
140   l_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
141   l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
142   lu_mem GCmemtrav;  /* memory traversed by the GC */
143   lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
144   stringtable strt;  /* hash table for strings */
145   TValue l_registry;
146   unsigned int seed;  /* randomized seed for hashes */
147   lu_byte currentwhite;
148   lu_byte gcstate;  /* state of garbage collector */
149   lu_byte gckind;  /* kind of GC running */
150   lu_byte gcrunning;  /* true if GC is running */
151   GCObject *allgc;  /* list of all collectable objects */
152   GCObject **sweepgc;  /* current position of sweep in list */
153   GCObject *finobj;  /* list of collectable objects with finalizers */
154   GCObject *gray;  /* list of gray objects */
155   GCObject *grayagain;  /* list of objects to be traversed atomically */
156   GCObject *weak;  /* list of tables with weak values */
157   GCObject *ephemeron;  /* list of ephemeron tables (weak keys) */
158   GCObject *allweak;  /* list of all-weak tables */
159   GCObject *tobefnz;  /* list of userdata to be GC */
160   GCObject *fixedgc;  /* list of objects not to be collected */
161   struct lua_State *twups;  /* list of threads with open upvalues */
162   unsigned int gcfinnum;  /* number of finalizers to call in each GC step */
163   int gcpause;  /* size of pause between successive GCs */
164   int gcstepmul;  /* GC 'granularity' */
165   lua_CFunction panic;  /* to be called in unprotected errors */
166   struct lua_State *mainthread;
167   const lua_Number *version;  /* pointer to version number */
168   TString *memerrmsg;  /* memory-error message */
169   TString *tmname[TM_N];  /* array with tag-method names */
170   struct Table *mt[LUA_NUMTAGS];  /* metatables for basic types */
171   TString *strcache[STRCACHE_N][STRCACHE_M];  /* cache for strings in API */
172 } global_State;
173 
174 
175 /*
176 ** 'per thread' state
177 */
178 struct lua_State {
179   CommonHeader;
180   unsigned short nci;  /* number of items in 'ci' list */
181   lu_byte status;
182   StkId top;  /* first free slot in the stack */
183   global_State *l_G;
184   CallInfo *ci;  /* call info for current function */
185   const Instruction *oldpc;  /* last pc traced */
186   StkId stack_last;  /* last free slot in the stack */
187   StkId stack;  /* stack base */
188   UpVal *openupval;  /* list of open upvalues in this stack */
189   GCObject *gclist;
190   struct lua_State *twups;  /* list of threads with open upvalues */
191   struct lua_longjmp *errorJmp;  /* current error recover point */
192   CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
193   volatile lua_Hook hook;
194   ptrdiff_t errfunc;  /* current error handling function (stack index) */
195   int stacksize;
196   int basehookcount;
197   int hookcount;
198   unsigned short nny;  /* number of non-yieldable calls in stack */
199   unsigned short nCcalls;  /* number of nested C calls */
200   l_signalT hookmask;
201   lu_byte allowhook;
202 };
203 
204 
205 #define G(L)	(L->l_G)
206 
207 
208 /*
209 ** Union of all collectable objects (only for conversions)
210 */
211 union GCUnion {
212   GCObject gc;  /* common header */
213   struct TString ts;
214   struct Udata u;
215   union Closure cl;
216   struct Table h;
217   struct Proto p;
218   struct lua_State th;  /* thread */
219 };
220 
221 
222 #define cast_u(o)	cast(union GCUnion *, (o))
223 
224 /* macros to convert a GCObject into a specific value */
225 #define gco2ts(o)  \
226 	check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
227 #define gco2u(o)  check_exp((o)->tt == LUA_TUSERDATA, &((cast_u(o))->u))
228 #define gco2lcl(o)  check_exp((o)->tt == LUA_TLCL, &((cast_u(o))->cl.l))
229 #define gco2ccl(o)  check_exp((o)->tt == LUA_TCCL, &((cast_u(o))->cl.c))
230 #define gco2cl(o)  \
231 	check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
232 #define gco2t(o)  check_exp((o)->tt == LUA_TTABLE, &((cast_u(o))->h))
233 #define gco2p(o)  check_exp((o)->tt == LUA_TPROTO, &((cast_u(o))->p))
234 #define gco2th(o)  check_exp((o)->tt == LUA_TTHREAD, &((cast_u(o))->th))
235 
236 
237 /* macro to convert a Lua object into a GCObject */
238 #define obj2gco(v) \
239 	check_exp(novariant((v)->tt) < LUA_TDEADKEY, (&(cast_u(v)->gc)))
240 
241 
242 /* actual number of total bytes allocated */
243 #define gettotalbytes(g)	cast(lu_mem, (g)->totalbytes + (g)->GCdebt)
244 
245 LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt);
246 LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1);
247 LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L);
248 LUAI_FUNC void luaE_freeCI (lua_State *L);
249 LUAI_FUNC void luaE_shrinkCI (lua_State *L);
250 
251 
252 #endif
253 
254