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package crypto
import "core:fmt"
import "core:os"
import "core:sys/unix"
_MAX_PER_CALL_BYTES :: 33554431 // 2^25 - 1
_rand_bytes :: proc (dst: []byte) {
dst := dst
l := len(dst)
for l > 0 {
to_read := min(l, _MAX_PER_CALL_BYTES)
ret := unix.sys_getrandom(raw_data(dst), uint(to_read), 0)
if ret < 0 {
switch os.Errno(-ret) {
case os.EINTR:
// Call interupted by a signal handler, just retry the
// request.
continue
case os.ENOSYS:
// The kernel is apparently prehistoric (< 3.17 circa 2014)
// and does not support getrandom.
panic("crypto: getrandom not available in kernel")
case:
// All other failures are things that should NEVER happen
// unless the kernel interface changes (ie: the Linux
// developers break userland).
panic(fmt.tprintf("crypto: getrandom failed: %d", ret))
}
}
l -= ret
dst = dst[ret:]
}
}
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