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| author | Roberto Ierusalimschy <roberto@inf.puc-rio.br> | 2018-05-16 08:27:59 -0300 |
|---|---|---|
| committer | Roberto Ierusalimschy <roberto@inf.puc-rio.br> | 2018-05-16 08:27:59 -0300 |
| commit | de53c2ec7ed5115ec78dd0c497d62dadb7eb2161 (patch) | |
| tree | 45dd40d965e3747f5071ce001e9986ca96eb555e | |
| parent | 80bd4a89407fcba641f0ea53379e93523943ea6a (diff) | |
| download | lua-de53c2ec7ed5115ec78dd0c497d62dadb7eb2161.tar.gz lua-de53c2ec7ed5115ec78dd0c497d62dadb7eb2161.tar.bz2 lua-de53c2ec7ed5115ec78dd0c497d62dadb7eb2161.zip | |
using some weak "randomness" (time and memory address) to initialize
seeds for the PRNG
| -rw-r--r-- | lmathlib.c | 31 |
1 files changed, 21 insertions, 10 deletions
| @@ -1,5 +1,5 @@ | |||
| 1 | /* | 1 | /* |
| 2 | ** $Id: lmathlib.c,v 1.132 2018/05/04 20:01:45 roberto Exp roberto $ | 2 | ** $Id: lmathlib.c,v 1.133 2018/05/09 14:54:37 roberto Exp roberto $ |
| 3 | ** Standard mathematical library | 3 | ** Standard mathematical library |
| 4 | ** See Copyright Notice in lua.h | 4 | ** See Copyright Notice in lua.h |
| 5 | */ | 5 | */ |
| @@ -14,6 +14,7 @@ | |||
| 14 | #include <limits.h> | 14 | #include <limits.h> |
| 15 | #include <math.h> | 15 | #include <math.h> |
| 16 | #include <stdlib.h> | 16 | #include <stdlib.h> |
| 17 | #include <time.h> | ||
| 17 | 18 | ||
| 18 | #include "lua.h" | 19 | #include "lua.h" |
| 19 | 20 | ||
| @@ -304,14 +305,15 @@ static Rand64 rotl (Rand64 x, int n) { | |||
| 304 | } | 305 | } |
| 305 | 306 | ||
| 306 | static Rand64 nextrand (Rand64 *state) { | 307 | static Rand64 nextrand (Rand64 *state) { |
| 307 | Rand64 res = rotl(state[1] * 5, 7) * 9; | 308 | Rand64 state0 = state[0]; |
| 308 | Rand64 t = state[1] << 17; | 309 | Rand64 state1 = state[1]; |
| 309 | state[2] ^= state[0]; | 310 | Rand64 state2 = state[2] ^ state0; |
| 310 | state[3] ^= state[1]; | 311 | Rand64 state3 = state[3] ^ state1; |
| 311 | state[1] ^= state[2]; | 312 | Rand64 res = rotl(state1 * 5, 7) * 9; |
| 312 | state[0] ^= state[3]; | 313 | state[0] = state0 ^ state3; |
| 313 | state[2] ^= t; | 314 | state[1] = state1 ^ state2; |
| 314 | state[3] = rotl(state[3], 45); | 315 | state[2] = state2 ^ (state1 << 17); |
| 316 | state[3] = rotl(state3, 45); | ||
| 315 | return res; | 317 | return res; |
| 316 | } | 318 | } |
| 317 | 319 | ||
| @@ -591,9 +593,18 @@ static const luaL_Reg randfuncs[] = { | |||
| 591 | {NULL, NULL} | 593 | {NULL, NULL} |
| 592 | }; | 594 | }; |
| 593 | 595 | ||
| 596 | |||
| 597 | /* | ||
| 598 | ** Register the random functions and initialize their state. | ||
| 599 | ** To give some "randomness" to the initial seed, use the current time | ||
| 600 | ** and the address of 'L' (in case the machine does address space layout | ||
| 601 | ** randomization). | ||
| 602 | */ | ||
| 594 | static void setrandfunc (lua_State *L) { | 603 | static void setrandfunc (lua_State *L) { |
| 595 | RanState *state = (RanState *)lua_newuserdatauv(L, sizeof(RanState), 0); | 604 | RanState *state = (RanState *)lua_newuserdatauv(L, sizeof(RanState), 0); |
| 596 | setseed(state->s, 0, 0); | 605 | lua_Unsigned seed1 = (lua_Unsigned)time(NULL); |
| 606 | lua_Unsigned seed2 = (lua_Unsigned)(size_t)L; | ||
| 607 | setseed(state->s, seed1, seed2); | ||
| 597 | luaL_setfuncs(L, randfuncs, 1); | 608 | luaL_setfuncs(L, randfuncs, 1); |
| 598 | } | 609 | } |
| 599 | 610 | ||