//! /system/services/vfs/vfs-test — a client that proves the VFS round trip end to end: open a
//! file through the `runtime` file API, write to it, seek back, read it, and compare.
//! On success it heartbeats "vfstest: ok" so the kernel test can observe it;
//! on failure it reports what went wrong. Shipped in the initial_ramdisk alongside vfs.

const std = @import("std");
const runtime = @import("runtime");

pub fn main(init: runtime.process.Init) void {
    const u = @import("posix").unistd;
    const payload = "hello-vfs";

    // The "park" role (the vfs-client-death test): open a file, then hold the
    // handle forever without closing — the kill and the VFS's release-on-death
    // are the point.
    if (init.arguments.count > 1) {
        var fd: i32 = -1;
        var tries: u32 = 0;
        while (fd < 0 and tries < 200) : (tries += 1) {
            fd = u.open("parked", u.O_CREAT);
            if (fd < 0) runtime.system.sleep(20);
        }
        if (fd < 0) {
            _ = runtime.system.write("vfstest: park open failed\n");
            return;
        }
        while (true) {
            _ = runtime.system.write("vfstest: parked\n");
            runtime.system.sleep(500);
        }
    }

    // The VFS server may not have registered yet — retry open until it's up.
    var fd: i32 = -1;
    var tries: u32 = 0;
    while (fd < 0 and tries < 200) : (tries += 1) {
        fd = u.open("greeting", u.O_CREAT);
        if (fd < 0) runtime.system.sleep(20);
    }
    if (fd < 0) {
        _ = runtime.system.write("vfstest: open failed\n");
        return;
    }

    if (u.write(fd, payload) != @as(isize, payload.len)) {
        _ = runtime.system.write("vfstest: write failed\n");
        return;
    }
    _ = u.lseek(fd, 0, u.SEEK_SET);

    var buffer: [32]u8 = undefined;
    const n = u.read(fd, &buffer);
    u.close(fd);

    if (n == @as(isize, payload.len) and std.mem.eql(u8, buffer[0..@intCast(n)], payload)) {
        while (true) {
            _ = runtime.system.write("vfstest: ok\n");
            runtime.system.sleep(1000);
        }
    }
    _ = runtime.system.write("vfstest: mismatch\n");
}

pub const panic = runtime.panic;
comptime {
    _ = &runtime.start._start;
}