patterns: Add ARIA2 Control format (#179)

README.md

@@ -26,6 +26,7 @@ Everything will immediately show up in ImHex's Content Store and gets bundled wi
 | 7Z | | [`patterns/7z.hexpat`](patterns/7z.hexpat) | 7z File Format |
 | AFE2 | | [`patterns/afe2.hexpat`](patterns/afe2.hexpat) | Nintendo Switch Atmosphère CFW Fatal Error log |
 | AR | `application/x-archive` | [`patterns/ar.hexpat`](patterns/ar.hexpat) | Static library archive files |
+| ARIA2 | | [`patterns/aria2.hexpat`](patterns/aria2.hexpat) | ARIA2 Download Manager Control files |
 | ARM VTOR | | [`patterns/arm_cm_vtor.hexpat`](patterns/arm_cm_vtor.hexpat) | ARM Cortex M Vector Table Layout |
 | Bencode | `application/x-bittorrent` | [`patterns/bencode.hexpat`](patterns/bencode.hexpat) | Bencode encoding, used by Torrent files |
 | BMP  | `image/bmp` | [`patterns/bmp.hexpat`](patterns/bmp.hexpat) | OS2/Windows Bitmap files |

patterns/aria2.hexpat

@@ -0,0 +1,36 @@
+#pragma author itsmeow
+#pragma description aria2 Control File
+
+#pragma endian big
+
+/*
+Format sourced from:
+https://aria2.github.io/manual/en/html/technical-notes.html#control-file-aria2-format
+
+Version 0 files are not supported by default
+However parsing one is as simple as changing to #pragma endian ittle
+and resolving any errors resulting from that by adding be prefixes to struct fields.
+*/
+
+struct AriaInFlight {
+    u32 index;
+    u32 length;
+    u32 bitfield_piece_length;
+    u8 bitfield_p[bitfield_piece_length];
+};
+
+struct AriaHeader {
+    u16 version;
+    u32 extension;
+    u32 infohash_length;
+    u8 infohash[infohash_length];
+    u32 piece_length;
+    u64 total_length;
+    u64 upload_length;
+    u32 bitfield_length;
+    u8 bitfield_d[bitfield_length];
+    u32 inflight_count;
+    AriaInFlight inflights[inflight_count];
+};
+
+AriaHeader aria_header @ 0x00;