diff options
Diffstat (limited to 'deps/v8/src/v8.cc')
-rw-r--r-- | deps/v8/src/v8.cc | 44 |
1 files changed, 17 insertions, 27 deletions
diff --git a/deps/v8/src/v8.cc b/deps/v8/src/v8.cc index 0b562fc28..11af057b1 100644 --- a/deps/v8/src/v8.cc +++ b/deps/v8/src/v8.cc @@ -100,42 +100,34 @@ void V8::TearDown() { } -static uint32_t random_seed() { - if (FLAG_random_seed == 0) { - return random(); +static void seed_random(uint32_t* state) { + for (int i = 0; i < 2; ++i) { + state[i] = FLAG_random_seed; + while (state[i] == 0) { + state[i] = random(); + } } - return FLAG_random_seed; } -typedef struct { - uint32_t hi; - uint32_t lo; -} random_state; +// Random number generator using George Marsaglia's MWC algorithm. +static uint32_t random_base(uint32_t* state) { + // Initialize seed using the system random(). + // No non-zero seed will ever become zero again. + if (state[0] == 0) seed_random(state); + // Mix the bits. Never replaces state[i] with 0 if it is nonzero. + state[0] = 18273 * (state[0] & 0xFFFF) + (state[0] >> 16); + state[1] = 36969 * (state[1] & 0xFFFF) + (state[1] >> 16); -// Random number generator using George Marsaglia's MWC algorithm. -static uint32_t random_base(random_state *state) { - // Initialize seed using the system random(). If one of the seeds - // should ever become zero again, or if random() returns zero, we - // avoid getting stuck with zero bits in hi or lo by re-initializing - // them on demand. - if (state->hi == 0) state->hi = random_seed(); - if (state->lo == 0) state->lo = random_seed(); - - // Mix the bits. - state->hi = 36969 * (state->hi & 0xFFFF) + (state->hi >> 16); - state->lo = 18273 * (state->lo & 0xFFFF) + (state->lo >> 16); - return (state->hi << 16) + (state->lo & 0xFFFF); + return (state[0] << 14) + (state[1] & 0x3FFFF); } // Used by JavaScript APIs uint32_t V8::Random(Isolate* isolate) { ASSERT(isolate == Isolate::Current()); - // TODO(isolates): move lo and hi to isolate - static random_state state = {0, 0}; - return random_base(&state); + return random_base(isolate->random_seed()); } @@ -144,9 +136,7 @@ uint32_t V8::Random(Isolate* isolate) { // leaks that could be used in an exploit. uint32_t V8::RandomPrivate(Isolate* isolate) { ASSERT(isolate == Isolate::Current()); - // TODO(isolates): move lo and hi to isolate - static random_state state = {0, 0}; - return random_base(&state); + return random_base(isolate->private_random_seed()); } |