Files
Odin/base/runtime/os_specific_linux.odin
Yawning Angel e1ba69ea51 base/runtime: Add rand_bytes and HAS_RAND_BYTES
Having the OS/runtime provide a cryptographic entropy source is the
right thing to do, and we need it to initialize the default random
number generator.
2025-11-29 10:45:53 +09:00

90 lines
2.3 KiB
Odin

#+private
package runtime
import "base:intrinsics"
_HAS_RAND_BYTES :: true
_stderr_write :: proc "contextless" (data: []byte) -> (int, _OS_Errno) {
when ODIN_ARCH == .amd64 {
SYS_write :: uintptr(1)
} else when ODIN_ARCH == .arm64 {
SYS_write :: uintptr(64)
} else when ODIN_ARCH == .i386 {
SYS_write :: uintptr(4)
} else when ODIN_ARCH == .arm32 {
SYS_write :: uintptr(4)
} else when ODIN_ARCH == .riscv64 {
SYS_write :: uintptr(64)
}
stderr :: 2
ret := int(intrinsics.syscall(SYS_write, uintptr(stderr), uintptr(raw_data(data)), uintptr(len(data))))
if ret < 0 && ret > -4096 {
return 0, _OS_Errno(-ret)
}
return ret, 0
}
_rand_bytes :: proc "contextless" (dst: []byte) {
when ODIN_ARCH == .amd64 {
SYS_getrandom :: uintptr(318)
} else when ODIN_ARCH == .arm64 {
SYS_getrandom :: uintptr(278)
} else when ODIN_ARCH == .i386 {
SYS_getrandom :: uintptr(355)
} else when ODIN_ARCH == .arm32 {
SYS_getrandom :: uintptr(384)
} else when ODIN_ARCH == .riscv64 {
SYS_getrandom :: uintptr(278)
} else {
#panic("base/runtime: no SYS_getrandom definition for target")
}
ERR_EINTR :: 4
ERR_ENOSYS :: 38
MAX_PER_CALL_BYTES :: 33554431 // 2^25 - 1
dst := dst
l := len(dst)
for l > 0 {
to_read := min(l, MAX_PER_CALL_BYTES)
ret := int(intrinsics.syscall(SYS_getrandom, uintptr(raw_data(dst[:to_read])), uintptr(to_read), uintptr(0)))
switch ret {
case -ERR_EINTR:
// Call interupted by a signal handler, just retry the
// request.
continue
case -ERR_ENOSYS:
// The kernel is apparently prehistoric (< 3.17 circa 2014)
// and does not support getrandom.
panic_contextless("base/runtime: getrandom not available in kernel")
case:
if ret < 0 {
// All other failures are things that should NEVER happen
// unless the kernel interface changes (ie: the Linux
// developers break userland).
panic_contextless("base/runtime: getrandom failed")
}
}
l -= ret
dst = dst[ret:]
}
}
_exit :: proc "contextless" (code: int) -> ! {
SYS_exit_group ::
231 when ODIN_ARCH == .amd64 else
248 when ODIN_ARCH == .arm32 else
94 when ODIN_ARCH == .arm64 else
252 when ODIN_ARCH == .i386 else
94 when ODIN_ARCH == .riscv64 else
0
intrinsics.syscall(uintptr(SYS_exit_group), uintptr(i32(code)))
unreachable()
}