danos/system/services/crash-test/crash-test.zig

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//! crash-test — a test fixture, not a driver: claims the device it is assigned,
//! hellos the device manager, announces itself, then faults on purpose. The
//! driver-restart scenario drives the manager's whole restart machinery with
//! it: fault → exit reason → backoff → respawn → the **same claim succeeding
//! again** (claim release on death, M17.1, through the manager's path) → the
//! crash-loop cap. Spawned bare (the initial-ramdisk sweep starts every bundled
//! binary), it exits silently so it cannot derange other tests.
const std = @import("std");
const runtime = @import("runtime");
const protocol = runtime.device_manager_protocol;
pub fn main(init: runtime.process.Init) void {
const argument = init.arguments.get(1) orelse return; // bare: stay silent
const assigned = std.fmt.parseInt(u64, argument, 10) catch return;
// The respawn only reaches this line because the kernel released the
// previous instance's claim at death. A failed claim exits cleanly — the
// manager reads "meant to stop" and the scenario fails loudly by silence.
if (!runtime.device.claim(assigned)) {
_ = runtime.system.write("crash-test: claim failed\n");
return;
}
var manager: ?runtime.ipc.Handle = null;
var tries: u32 = 0;
while (manager == null and tries < 100) : (tries += 1) {
manager = runtime.ipc.lookup(.device_manager);
if (manager == null) runtime.system.sleep(20);
}
const h = manager orelse return;
const hello = protocol.Hello{ .role = @intFromEnum(protocol.Role.device), .device_id = assigned };
var reply: [protocol.message_maximum]u8 = undefined;
_ = runtime.ipc.call(h, std.mem.asBytes(&hello), &reply) catch return;
_ = runtime.system.write("crash-test: faulting now\n");
const poison: *volatile u32 = @ptrFromInt(0xdead0000);
poison.* = 1; // the restart machinery's fuel: a real segmentation fault
}