Tidy up Oar Entry default data

src/oar.zig

@@ -7,19 +7,19 @@ const sys = @import("./sys.zig");
 /// Typically, following this block in memory is the file data it holds the meta-information for.
 ///
 pub const Entry = extern struct {
-    signature: [3]u8,
+    signature: [3]u8 = signature_magic,
     revision: u8,
-    name_length: u8,
+    name_length: u8 = 0,
     name_buffer: [255]u8 = std.mem.zeroes([255]u8),
     file_size: u64,
-    padding: [244]u8,
+    padding: [244]u8 = std.mem.zeroes([244]u8),
 
     ///
     /// Returns `true` if `entry` correctly identifies itself as a valid Oar entry, otherwise
     /// `false`.
     ///
     pub fn isValid(entry: Entry) bool {
-        return std.mem.eql(u8, &entry.signature, "oar");
+        return std.mem.eql(u8, &entry.signature, signature_magic[0 ..]);
     }
 
     ///
@@ -44,5 +44,5 @@ pub const Entry = extern struct {
     ///
     /// Magic identifier used to validate [Entry] data.
     ///
-    const signature_magic = "oar";
+    const signature_magic = [3]u8{'o', 'a', 'r'};
 };