fix pointer initialization

src/main.zig

@@ -16,10 +16,6 @@ pub fn main() !void {
     try bw.flush(); // don't forget to flush!
 }
 
-const Tunnel = struct {
-    name: []u8,
-};
-
 test "simple test" {
     var list = std.ArrayList(i32).init(std.testing.allocator);
     defer list.deinit(); // try commenting this out and see if zig detects the memory leak!

src/tunnel.zig

@@ -9,8 +9,7 @@ const IFF_TUN = 0x0001; // <linux/if_tun.h>
 const IFF_NO_PI = 0x1000; // <linux/if_tun.h>
 const TUNSETIFF = 0x400454ca; // compile a C program, run and see
 
-dev_buf: [posix.IFNAMESIZE:0]u8,
-dev: [:0]u8,
+dev: [posix.IFNAMESIZE:0]u8,
 tunFile: posix.fd_t,
 
 pub fn init(devname: ?[]const u8) !Tunnel {
@@ -41,17 +40,12 @@ pub fn init(devname: ?[]const u8) !Tunnel {
     }
 
     var tunnel = Tunnel{
-        .dev = undefined,
-        .dev_buf = .{0} ** posix.IFNAMESIZE,
+        .dev = .{0} ** posix.IFNAMESIZE,
         .tunFile = tunFile,
     };
 
     const ifname = mem.sliceTo(&ifr.ifrn.name, 0);
-    @memcpy(tunnel.dev_buf[0..ifname.len], ifname);
-    tunnel.dev = tunnel.dev_buf[0..ifname.len :0];
-    std.debug.print("&tunnel = {*}\n", .{&tunnel});
-    std.debug.print("&tunnel.dev = {*}\n", .{tunnel.dev});
-
+    @memcpy(tunnel.dev[0..ifname.len], ifname);
     return tunnel;
 }
 
@@ -61,10 +55,14 @@ pub fn close(self: *Tunnel) void {
 
 const Tunnel = @This();
 
-test "init" {
+test "init with a known name" {
     var tun = try init("nyotun");
-    std.debug.print("&tun = {*}\n", .{&tun});
-    std.debug.print("&tun.dev = {*}\n", .{tun.dev});
-    try std.testing.expectEqualStrings("nyotun", tun.dev);
-    tun.close();
+    defer tun.close();
+    try std.testing.expectEqualStrings("nyotun", mem.sliceTo(&tun.dev, 0));
+}
+
+test "init with no name" {
+    var tun = try init(null);
+    defer tun.close();
+    try std.testing.expectStringStartsWith(mem.sliceTo(&tun.dev, 0), "tun");
 }