import (
	"internal/abi"
	"unsafe"
)

//go:cgo_import_dynamic libc_arc4random_buf arc4random_buf "/usr/lib/libSystem.B.dylib"

func libc_arc4random_buf_trampoline()

// ARC4Random calls the macOS arc4random_buf(3) function.
func ARC4Random(p []byte) {
	// macOS 11 and 12 abort if length is 0.
	if len(p) == 0 {
		return
	}
	syscall_syscall(abi.FuncPCABI0(libc_arc4random_buf_trampoline),

	//
	// "The subsystem is re-seeded from the kernel random number subsystem on a
	// regular basis, and also upon fork(2)." - arc4random(3)
	//
	// Note that despite its legacy name, it uses a secure CSPRNG (not RC4) in
	// all supported macOS versions.
	altGetRandom = func(b []byte) error { unix.ARC4Random(b); return nil }