Cleanup asBytes and test it

src/message.zig

@@ -91,7 +91,7 @@ pub const ZeroCopyMessage = packed struct {
     }
 
     pub fn deinit(self: *Self, allocator: Allocator) void {
-        allocator.free(self.toBytes());
+        allocator.free(self.asBytes());
     }
 
     fn getRelay(self: *Self) *align(1) Relay {
@@ -143,17 +143,25 @@ pub const ZeroCopyMessage = packed struct {
         self.length = nativeToBig(@TypeOf(self.length), self.length);
     }
 
-    pub fn fromBytesUnchecked(bytes: []align(@alignOf(Self)) u8) *Self {
-        return @ptrCast(@alignCast(bytes.ptr));
+    pub fn bytesAsValueUnchecked(bytes: []align(@alignOf(Self)) u8) *Self {
+        return std.mem.bytesAsValue(Self, bytes);
     }
 
-    pub fn fromBytes(bytes: []align(@alignOf(Self)) u8) !*Self {
-        const res: *Self = @ptrCast(@alignCast(bytes.ptr));
-        return if (bytes.len == res.length + @sizeOf(Self)) res else Error.InvalidMessage;
+    pub fn bytesAsValue(bytes: []align(@alignOf(Self)) u8) !*Self {
+        const res = bytesAsValueUnchecked(bytes);
+        return switch (res.type) {
+            .relay, .connection => if (bytes.len == res.length + @sizeOf(Self))
+                res
+            else
+                Error.InvalidMessage,
+            .file_transfer => Error.NotImplementedSaprusType,
+            else => Error.UnknownSaprusType,
+        };
     }
 
-    pub fn toBytes(self: *Self) []align(@alignOf(Self)) u8 {
-        return @as([*]align(@alignOf(Self)) u8, @ptrCast(self))[0 .. @sizeOf(Self) + self.length];
+    pub fn asBytes(self: *Self) []align(@alignOf(Self)) u8 {
+        const size = @sizeOf(Self) + self.length;
+        return @as([*]align(@alignOf(Self)) u8, @ptrCast(self))[0..size];
     }
 };
 
@@ -178,14 +186,14 @@ test "testing variable length zero copy struct" {
     }
 
     {
-        const bytes = zcm.toBytes();
+        const bytes = zcm.asBytes();
 
         // Print the message as hex using the network byte order
         try zcm.networkFromNativeEndian();
         // We know the error from nativeFromNetworkEndian is unreachable because
         // it would have returned an error from networkFromNativeEndian.
         defer zcm.nativeFromNetworkEndian() catch unreachable;
-        std.debug.print("network bytes: {s}\n", .{bytes});
+        std.debug.print("network bytes: {x}\n", .{bytes});
         std.debug.print("bytes len: {d}\n", .{bytes.len});
     }
 
@@ -193,6 +201,8 @@ test "testing variable length zero copy struct" {
         // Illegal behavior
         std.debug.print("{any}\n", .{(try zcm.getSaprusTypePayload()).connection});
     }
+
+    try std.testing.expectEqualDeep(zcm, try ZeroCopyMessage.bytesAsValue(zcm.asBytes()));
 }
 
 /// All Saprus messages