1*dfc11533SChris Williamson /*
2*dfc11533SChris Williamson ** $Id: lstring.c,v 2.26.1.1 2013/04/12 18:48:47 roberto Exp $
3*dfc11533SChris Williamson ** String table (keeps all strings handled by Lua)
4*dfc11533SChris Williamson ** See Copyright Notice in lua.h
5*dfc11533SChris Williamson */
6*dfc11533SChris Williamson
7*dfc11533SChris Williamson
8*dfc11533SChris Williamson #include <sys/zfs_context.h>
9*dfc11533SChris Williamson
10*dfc11533SChris Williamson #define lstring_c
11*dfc11533SChris Williamson #define LUA_CORE
12*dfc11533SChris Williamson
13*dfc11533SChris Williamson #include "lua.h"
14*dfc11533SChris Williamson
15*dfc11533SChris Williamson #include "lmem.h"
16*dfc11533SChris Williamson #include "lobject.h"
17*dfc11533SChris Williamson #include "lstate.h"
18*dfc11533SChris Williamson #include "lstring.h"
19*dfc11533SChris Williamson
20*dfc11533SChris Williamson
21*dfc11533SChris Williamson /*
22*dfc11533SChris Williamson ** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to
23*dfc11533SChris Williamson ** compute its hash
24*dfc11533SChris Williamson */
25*dfc11533SChris Williamson #if !defined(LUAI_HASHLIMIT)
26*dfc11533SChris Williamson #define LUAI_HASHLIMIT 5
27*dfc11533SChris Williamson #endif
28*dfc11533SChris Williamson
29*dfc11533SChris Williamson
30*dfc11533SChris Williamson /*
31*dfc11533SChris Williamson ** equality for long strings
32*dfc11533SChris Williamson */
luaS_eqlngstr(TString * a,TString * b)33*dfc11533SChris Williamson int luaS_eqlngstr (TString *a, TString *b) {
34*dfc11533SChris Williamson size_t len = a->tsv.len;
35*dfc11533SChris Williamson lua_assert(a->tsv.tt == LUA_TLNGSTR && b->tsv.tt == LUA_TLNGSTR);
36*dfc11533SChris Williamson return (a == b) || /* same instance or... */
37*dfc11533SChris Williamson ((len == b->tsv.len) && /* equal length and ... */
38*dfc11533SChris Williamson (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */
39*dfc11533SChris Williamson }
40*dfc11533SChris Williamson
41*dfc11533SChris Williamson
42*dfc11533SChris Williamson /*
43*dfc11533SChris Williamson ** equality for strings
44*dfc11533SChris Williamson */
luaS_eqstr(TString * a,TString * b)45*dfc11533SChris Williamson int luaS_eqstr (TString *a, TString *b) {
46*dfc11533SChris Williamson return (a->tsv.tt == b->tsv.tt) &&
47*dfc11533SChris Williamson (a->tsv.tt == LUA_TSHRSTR ? eqshrstr(a, b) : luaS_eqlngstr(a, b));
48*dfc11533SChris Williamson }
49*dfc11533SChris Williamson
50*dfc11533SChris Williamson
luaS_hash(const char * str,size_t l,unsigned int seed)51*dfc11533SChris Williamson unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {
52*dfc11533SChris Williamson unsigned int h = seed ^ cast(unsigned int, l);
53*dfc11533SChris Williamson size_t l1;
54*dfc11533SChris Williamson size_t step = (l >> LUAI_HASHLIMIT) + 1;
55*dfc11533SChris Williamson for (l1 = l; l1 >= step; l1 -= step)
56*dfc11533SChris Williamson h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1]));
57*dfc11533SChris Williamson return h;
58*dfc11533SChris Williamson }
59*dfc11533SChris Williamson
60*dfc11533SChris Williamson
61*dfc11533SChris Williamson /*
62*dfc11533SChris Williamson ** resizes the string table
63*dfc11533SChris Williamson */
luaS_resize(lua_State * L,int newsize)64*dfc11533SChris Williamson void luaS_resize (lua_State *L, int newsize) {
65*dfc11533SChris Williamson int i;
66*dfc11533SChris Williamson stringtable *tb = &G(L)->strt;
67*dfc11533SChris Williamson /* cannot resize while GC is traversing strings */
68*dfc11533SChris Williamson luaC_runtilstate(L, ~bitmask(GCSsweepstring));
69*dfc11533SChris Williamson if (newsize > tb->size) {
70*dfc11533SChris Williamson luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
71*dfc11533SChris Williamson for (i = tb->size; i < newsize; i++) tb->hash[i] = NULL;
72*dfc11533SChris Williamson }
73*dfc11533SChris Williamson /* rehash */
74*dfc11533SChris Williamson for (i=0; i<tb->size; i++) {
75*dfc11533SChris Williamson GCObject *p = tb->hash[i];
76*dfc11533SChris Williamson tb->hash[i] = NULL;
77*dfc11533SChris Williamson while (p) { /* for each node in the list */
78*dfc11533SChris Williamson GCObject *next = gch(p)->next; /* save next */
79*dfc11533SChris Williamson unsigned int h = lmod(gco2ts(p)->hash, newsize); /* new position */
80*dfc11533SChris Williamson gch(p)->next = tb->hash[h]; /* chain it */
81*dfc11533SChris Williamson tb->hash[h] = p;
82*dfc11533SChris Williamson resetoldbit(p); /* see MOVE OLD rule */
83*dfc11533SChris Williamson p = next;
84*dfc11533SChris Williamson }
85*dfc11533SChris Williamson }
86*dfc11533SChris Williamson if (newsize < tb->size) {
87*dfc11533SChris Williamson /* shrinking slice must be empty */
88*dfc11533SChris Williamson lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
89*dfc11533SChris Williamson luaM_reallocvector(L, tb->hash, tb->size, newsize, GCObject *);
90*dfc11533SChris Williamson }
91*dfc11533SChris Williamson tb->size = newsize;
92*dfc11533SChris Williamson }
93*dfc11533SChris Williamson
94*dfc11533SChris Williamson
95*dfc11533SChris Williamson /*
96*dfc11533SChris Williamson ** creates a new string object
97*dfc11533SChris Williamson */
createstrobj(lua_State * L,const char * str,size_t l,int tag,unsigned int h,GCObject ** list)98*dfc11533SChris Williamson static TString *createstrobj (lua_State *L, const char *str, size_t l,
99*dfc11533SChris Williamson int tag, unsigned int h, GCObject **list) {
100*dfc11533SChris Williamson TString *ts;
101*dfc11533SChris Williamson size_t totalsize; /* total size of TString object */
102*dfc11533SChris Williamson totalsize = sizeof(TString) + ((l + 1) * sizeof(char));
103*dfc11533SChris Williamson ts = &luaC_newobj(L, tag, totalsize, list, 0)->ts;
104*dfc11533SChris Williamson ts->tsv.len = l;
105*dfc11533SChris Williamson ts->tsv.hash = h;
106*dfc11533SChris Williamson ts->tsv.extra = 0;
107*dfc11533SChris Williamson memcpy(ts+1, str, l*sizeof(char));
108*dfc11533SChris Williamson ((char *)(ts+1))[l] = '\0'; /* ending 0 */
109*dfc11533SChris Williamson return ts;
110*dfc11533SChris Williamson }
111*dfc11533SChris Williamson
112*dfc11533SChris Williamson
113*dfc11533SChris Williamson /*
114*dfc11533SChris Williamson ** creates a new short string, inserting it into string table
115*dfc11533SChris Williamson */
newshrstr(lua_State * L,const char * str,size_t l,unsigned int h)116*dfc11533SChris Williamson static TString *newshrstr (lua_State *L, const char *str, size_t l,
117*dfc11533SChris Williamson unsigned int h) {
118*dfc11533SChris Williamson GCObject **list; /* (pointer to) list where it will be inserted */
119*dfc11533SChris Williamson stringtable *tb = &G(L)->strt;
120*dfc11533SChris Williamson TString *s;
121*dfc11533SChris Williamson if (tb->nuse >= cast(lu_int32, tb->size) && tb->size <= MAX_INT/2)
122*dfc11533SChris Williamson luaS_resize(L, tb->size*2); /* too crowded */
123*dfc11533SChris Williamson list = &tb->hash[lmod(h, tb->size)];
124*dfc11533SChris Williamson s = createstrobj(L, str, l, LUA_TSHRSTR, h, list);
125*dfc11533SChris Williamson tb->nuse++;
126*dfc11533SChris Williamson return s;
127*dfc11533SChris Williamson }
128*dfc11533SChris Williamson
129*dfc11533SChris Williamson
130*dfc11533SChris Williamson /*
131*dfc11533SChris Williamson ** checks whether short string exists and reuses it or creates a new one
132*dfc11533SChris Williamson */
internshrstr(lua_State * L,const char * str,size_t l)133*dfc11533SChris Williamson static TString *internshrstr (lua_State *L, const char *str, size_t l) {
134*dfc11533SChris Williamson GCObject *o;
135*dfc11533SChris Williamson global_State *g = G(L);
136*dfc11533SChris Williamson unsigned int h = luaS_hash(str, l, g->seed);
137*dfc11533SChris Williamson for (o = g->strt.hash[lmod(h, g->strt.size)];
138*dfc11533SChris Williamson o != NULL;
139*dfc11533SChris Williamson o = gch(o)->next) {
140*dfc11533SChris Williamson TString *ts = rawgco2ts(o);
141*dfc11533SChris Williamson if (h == ts->tsv.hash &&
142*dfc11533SChris Williamson l == ts->tsv.len &&
143*dfc11533SChris Williamson (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
144*dfc11533SChris Williamson if (isdead(G(L), o)) /* string is dead (but was not collected yet)? */
145*dfc11533SChris Williamson changewhite(o); /* resurrect it */
146*dfc11533SChris Williamson return ts;
147*dfc11533SChris Williamson }
148*dfc11533SChris Williamson }
149*dfc11533SChris Williamson return newshrstr(L, str, l, h); /* not found; create a new string */
150*dfc11533SChris Williamson }
151*dfc11533SChris Williamson
152*dfc11533SChris Williamson
153*dfc11533SChris Williamson /*
154*dfc11533SChris Williamson ** new string (with explicit length)
155*dfc11533SChris Williamson */
luaS_newlstr(lua_State * L,const char * str,size_t l)156*dfc11533SChris Williamson TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
157*dfc11533SChris Williamson if (l <= LUAI_MAXSHORTLEN) /* short string? */
158*dfc11533SChris Williamson return internshrstr(L, str, l);
159*dfc11533SChris Williamson else {
160*dfc11533SChris Williamson if (l + 1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
161*dfc11533SChris Williamson luaM_toobig(L);
162*dfc11533SChris Williamson return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed, NULL);
163*dfc11533SChris Williamson }
164*dfc11533SChris Williamson }
165*dfc11533SChris Williamson
166*dfc11533SChris Williamson
167*dfc11533SChris Williamson /*
168*dfc11533SChris Williamson ** new zero-terminated string
169*dfc11533SChris Williamson */
luaS_new(lua_State * L,const char * str)170*dfc11533SChris Williamson TString *luaS_new (lua_State *L, const char *str) {
171*dfc11533SChris Williamson return luaS_newlstr(L, str, strlen(str));
172*dfc11533SChris Williamson }
173*dfc11533SChris Williamson
174*dfc11533SChris Williamson
luaS_newudata(lua_State * L,size_t s,Table * e)175*dfc11533SChris Williamson Udata *luaS_newudata (lua_State *L, size_t s, Table *e) {
176*dfc11533SChris Williamson Udata *u;
177*dfc11533SChris Williamson if (s > MAX_SIZET - sizeof(Udata))
178*dfc11533SChris Williamson luaM_toobig(L);
179*dfc11533SChris Williamson u = &luaC_newobj(L, LUA_TUSERDATA, sizeof(Udata) + s, NULL, 0)->u;
180*dfc11533SChris Williamson u->uv.len = s;
181*dfc11533SChris Williamson u->uv.metatable = NULL;
182*dfc11533SChris Williamson u->uv.env = e;
183*dfc11533SChris Williamson return u;
184*dfc11533SChris Williamson }
185*dfc11533SChris Williamson
186