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//go:build linux && !baremetal && !wasip1
// This implementation of crypto/rand uses the /dev/urandom pseudo-file to
// generate random numbers.
// TODO: convert to the getentropy or getrandom libc function on Linux once it
// is more widely supported.
package rand
import (
"syscall"
)
func init() {
Reader = &reader{}
}
type reader struct {
fd int
}
func (r *reader) Read(b []byte) (n int, err error) {
if len(b) == 0 {
return
}
// Open /dev/urandom first if needed.
if r.fd == 0 {
fd, err := syscall.Open("/dev/urandom", syscall.O_RDONLY, 0)
if err != nil {
return 0, err
}
r.fd = fd
}
// Read from the file.
return syscall.Read(r.fd, b)
}
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