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#include "libbb.h"
#include "../shell/random.h"
/* call 'fn' to put data in 'dt' then copy it to generator state */
#define GET_DATA(fn, dt) \
fn(&dt); \
u = (uint32_t *)&dt; \
for (j=0; j<sizeof(dt)/sizeof(uint32_t); ++j) { \
state[i++%2] ^= *u++; \
}
/*
* Obtain a few bytes of random-ish data to initialise the generator.
* This is unlikely to be very robust: don't rely on it for
* anything that needs to be secure.
*/
static void get_entropy(uint32_t state[2])
{
int i, j;
SYSTEMTIME tm;
MEMORYSTATUS ms;
SYSTEM_INFO si;
LARGE_INTEGER pc;
uint32_t *u;
i = 0;
state[i++%2] ^= (uint32_t)GetCurrentProcessId();
state[i++%2] ^= (uint32_t)GetCurrentThreadId();
state[i++%2] ^= (uint32_t)GetTickCount();
GET_DATA(GetLocalTime, tm)
GET_DATA(GlobalMemoryStatus, ms)
GET_DATA(GetSystemInfo, si)
GET_DATA(QueryPerformanceCounter, pc)
#if 0
{
unsigned char *p = (unsigned char *)state;
for (j=0; j<8; ++j) {
fprintf(stderr, "%02x", *p++);
if ((j&3) == 3) {
fprintf(stderr, " ");
}
}
fprintf(stderr, "\n");
}
#endif
}
ssize_t get_random_bytes(void *buf, ssize_t count)
{
static random_t rnd;
ssize_t save_count = count;
uint32_t value;
unsigned char *ptr = (unsigned char *)&value;
if (buf == NULL || count < 0) {
errno = EINVAL;
return -1;
}
if (UNINITED_RANDOM_T(&rnd)) {
uint32_t state[2] = {0, 0};
get_entropy(state);
INIT_RANDOM_T(&rnd, state[0] ? state[0] : 1, state[1]);
}
for (;count > 0; buf+=4, count-=4) {
value = full_random(&rnd);
memcpy(buf, ptr, count >= 4 ? 4 : count);
}
return save_count;
}
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