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#ifdef HAVE_GETRANDOM
#define _GNU_SOURCE
#include <errno.h>
#ifdef HAVE_LIBC_GETRANDOM
#include <sys/random.h>
#else
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <linux/random.h>
#ifndef SYS_getrandom
#define SYS_getrandom __NR_getrandom
#endif
static ssize_t getrandom(void* buf, size_t buflen, unsigned int flags)
{
return syscall(SYS_getrandom, buf, buflen, flags);
}
#endif
int system_has_getrandom()
{
char tmp;
return getrandom(&tmp, sizeof(tmp), GRND_NONBLOCK) != -1 || errno != ENOSYS;
}
// Returns 0 on success, non-zero on failure.
int entropy_getrandom(unsigned char* buf, size_t len)
{
while (len) {
ssize_t bytes_read = getrandom(buf, len, 0);
if (bytes_read == -1) {
if (errno != EINTR)
return -1;
else
continue;
}
len -= bytes_read;
buf += bytes_read;
}
return 0;
}
#endif
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