Simplify RawSocketWriter

Does not need to use an allocator anymor.
Just uses the internal buffer properly.

src/RawSocketWriter.zig

@@ -1,45 +1,31 @@
 const std = @import("std");
 const gcat = @import("gatorcat");
-const Writer = @This();
+const RawSocketWriter = @This();
+const Writer = std.Io.Writer;
 const assert = std.debug.assert;
 
-interface: std.Io.Writer,
+interface: Writer,
 socket: gcat.nic.RawSocket,
-alloc: std.mem.Allocator,
 
-fn drain(io_w: *std.Io.Writer, data: []const []const u8, splat: usize) std.Io.Writer.Error!usize {
-    const w: *Writer = @alignCast(@fieldParentPtr("interface", io_w));
+fn drain(io_w: *std.Io.Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
+    const w: *RawSocketWriter = @alignCast(@fieldParentPtr("interface", io_w));
+    const rem_buf = io_w.unusedCapacitySlice();
+    var rem_w = Writer.fixed(rem_buf);
+    const res = rem_w.writeSplat(data, splat) catch rem_buf.len;
+    io_w.advance(res);
     const buffered = io_w.buffered();
-    var res: usize = 0;
-    if (buffered.len > 0) {
     w.socket.linkLayer().send(buffered) catch return error.WriteFailed;
     _ = io_w.consumeAll();
-    }
-
-    for (data[0 .. data.len - 1]) |d| {
-        w.socket.linkLayer().send(d) catch return error.WriteFailed;
-        res += d.len;
-    }
-
-    if (splat > 0 and data[data.len - 1].len > 0) {
-        var splatBuffer: std.ArrayList(u8) = .empty;
-        defer splatBuffer.deinit(w.alloc);
-        for (0..splat) |_| {
-            splatBuffer.appendSlice(w.alloc, data[data.len - 1]) catch return error.WriteFailed;
-        }
-        w.socket.linkLayer().send(splatBuffer.items) catch return error.WriteFailed;
-    }
 
     return res;
 }
 
-pub fn init(interface_name: [:0]const u8, buffer: []u8, alloc: std.mem.Allocator) !Writer {
+pub fn init(interface_name: [:0]const u8, buffer: []u8) !RawSocketWriter {
     return .{
         .interface = .{
             .vtable = &.{ .drain = drain },
             .buffer = buffer,
         },
         .socket = try .init(interface_name),
-        .alloc = alloc,
     };
 }

src/main.zig

@@ -47,7 +47,7 @@ pub fn main() !void {
     }
 
     var sock_buffer: [2048]u8 = undefined;
-    var rawSocketWriter: RawSocketWriter = try .init("enp7s0", &sock_buffer, gpa); // /proc/net/dev
+    var rawSocketWriter: RawSocketWriter = try .init("enp7s0", &sock_buffer); // /proc/net/dev
     var client = try SaprusClient.init(&rawSocketWriter.interface);
     defer client.deinit();