danos/system/services/shm-client/shm-client.zig

52 lines
1.6 KiB
Zig

//! system/services/shm-client — the creating half of the shm test (docs/display-v2.md V2).
//! It `shm_create`s a shared region, writes a known pattern into it, and hands the region's
//! capability to `shm-server` as an `ipc_call` send_cap. The server maps that capability and
//! confirms the pattern is visible — proving cross-process shared memory over the extended
//! capability-passing path.
const runtime = @import("runtime");
const system = runtime.system;
const shm = runtime.shm;
const ipc = runtime.ipc;
const pattern_len = 4096;
/// The pattern the server checks — must match shm-server.zig.
fn expected(i: usize) u8 {
return @truncate(i *% 7 +% 3);
}
fn lookupServer() ?ipc.Handle {
var attempts: usize = 0;
while (attempts < 100) : (attempts += 1) {
if (ipc.lookup(.shm_test)) |h| return h;
system.sleep(50);
}
return null;
}
pub fn main() void {
const region = shm.create(pattern_len) orelse {
_ = system.write("shm: create failed\n");
return;
};
var i: usize = 0;
while (i < pattern_len) : (i += 1) region.ptr[i] = expected(i);
const server = lookupServer() orelse {
_ = system.write("shm: no server\n");
return;
};
// A non-empty message (so it reaches on_message, not the ping path), carrying the shm
// region's capability. The reply is empty; we just need the round trip.
var reply: [64]u8 = undefined;
_ = ipc.callCap(server, "shm", &reply, region.handle) catch {
_ = system.write("shm: call failed\n");
};
}
pub const panic = runtime.panic;
comptime {
_ = &runtime.start._start;
}