1 files changed, 17 insertions, 6 deletions
diff --git a/src/channel.zig b/src/channel.zig
index 6367463..b3084b8 100644
--- a/src/channel.zig
+++ b/src/channel.zig
@@ -14,6 +14,7 @@ pub const Message = struct {
     bytes: []const u8,
     refcount: usize = 1,
     process_filter: u16,
+    sender: u16,
 
     fn addReference(self: *Message) !void {
         self.refcount = try std.math.add(usize, self.refcount, 1);
@@ -33,10 +34,10 @@ var alloc: Allocator = undefined;
 
 const Queues = std.AutoArrayHashMap(usize, Messages);
 
-const Processes = std.AutoArrayHashMap(usize, Queues);
+const Processes = std.AutoArrayHashMap(u16, Queues);
 var joined: Processes = undefined;
 
-pub fn join(pid: usize, id: usize) !void {
+pub fn join(pid: u16, id: usize) !void {
     const queues = try joined.getOrPut(pid);
     if (!queues.found_existing) {
         initProcess(queues.value_ptr);
@@ -48,7 +49,7 @@ pub fn join(pid: usize, id: usize) !void {
     }
 }
 
-pub fn leave(pid: usize, id: usize) void {
+pub fn leave(pid: u16, id: usize) void {
     const queues = joined.getPtr(pid) orelse return;
     freeQueues(queues);
     queues.clearAndFree();
@@ -56,11 +57,15 @@ pub fn leave(pid: usize, id: usize) void {
 }
 
 // The channel takes ownership of `bytes`.
-pub fn pass(id: usize, receiver: u16, bytes: []const u8) !void {
+pub fn pass(pid: u16, id: usize, receiver: u16, bytes: []const u8) !void {
     const message = try alloc.create(Message);
     defer message.dropReference();
 
-    message.* = .{ .bytes = bytes, .process_filter = receiver };
+    message.* = .{
+        .bytes = bytes,
+        .process_filter = receiver,
+        .sender = pid,
+    };
 
     var it = joined.iterator();
     while (it.next()) |queues| {
@@ -73,7 +78,7 @@ pub fn pass(id: usize, receiver: u16, bytes: []const u8) !void {
     }
 }
 
-pub fn receive(pid: usize, id: usize, buffer: []u8) !usize {
+pub fn receive(pid: u16, id: usize, sender: ?*u16, buffer: []u8) !usize {
     const queues = joined.getPtr(pid) orelse return Error.NotJoined;
     const messages = queues.getPtr(id) orelse return Error.NotJoined;
     const message = messages.popFirst() orelse return Error.WouldBlock;
@@ -81,6 +86,12 @@ pub fn receive(pid: usize, id: usize, buffer: []u8) !usize {
     defer alloc.destroy(message);
     defer message.data.dropReference();
 
+    if (message.data.process_filter != pid and message.data.process_filter != 0) {
+        return Error.WouldBlock;
+    }
+
+    if (sender) |sender_id| sender_id.* = message.data.sender;
+
     const len = @min(buffer.len, message.data.bytes.len);
     @memcpy(buffer[0..len], message.data.bytes[0..len]);